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1

Lagrangian simulations contribution to the knowledge of discs and doughnuts pulsed solvent extraction columns hydrodynamics  

Microsoft Academic Search

This paper intends to evaluate in which way the Computational Fluid Dynamics (CFD), and more precisely Lagrangian simulations, can be used as a tool for getting information about the hydrodynamic behavior of the dispersed phase in extraction columns. As an example, the study is carried out on a particular contactor: the discs and doughnuts pulsed column. In a first part,

N. Bardin-Monnier; P. Guiraud; C. Gourdon

2003-01-01

2

Copper extraction from ammoniacal medium in a pulsed sieve-plate column with LIX 84-I.  

PubMed

This article reports on a study of copper removal from ammoniacal aqueous solution (1.0 kg m(-3) Cu, pH 9.5) by liquid-liquid extraction using a pulsed sieve-plate column. The extractant tested was the hydroxyoxime LIX 84-I (2-hydroxy-5-nonylacetophenone oxime) in the aliphatic diluent Shellsol D-70. The results of the pilot plant experiments demonstrated the feasibility of operating the extraction process in this type of column, with efficiencies of copper removal in the range of 90.5-99.5%. Several effects on the column performance were examined, namely the aqueous and organic flow rates and the pulse velocity. The axial dispersion model was applied to simulate the concentration profiles, which reasonably predicted the experimental data. The overall mass transfer coefficient was evaluated from the experimental data and was found to be between 9×10(-6) and 1.2×10(-5) m s(-1). These data were compared with the ones obtained from the resistances in series model, which indicated that the resistance due to chemical reaction was 84-91% of the overall resistance to mass transfer. The extraction using a hollow fiber contactor was also carried out to compare the membrane process performance with the one of conventional process. PMID:20675049

Gameiro, M Lurdes F; Machado, Remígio M; Ismael, M Rosinda C; Reis, M Teresa A; Carvalho, Jorge M R

2010-08-02

3

Numerical experimentation: a tool to calculate the axial dispersion coefficient in discs and doughnuts pulsed solvent extraction columns  

Microsoft Academic Search

In this paper, a correlation between axial mixing in a discs and doughnuts pulsed extraction column, the geometrical characteristics of the column, and the pulsation conditions is established by numerical experimentation. The calculation method, based on the computational fluid dynamics approach and detailed on an example, consists in evaluating the axial dispersion coefficient from simulations of tracer mixing, transported by

M. Aoun Nabli; P. Guiraud; C. Gourdon

1997-01-01

4

SPIRAL CONTACTOR FOR SOLVENT EXTRACTION COLUMN  

DOEpatents

The patented extraction apparatus includes a column, perforated plates extending across the column, liquid pulse means connected to the column, and an imperforate spiral ribbon along the length of the column.

Cooley, C.R.

1961-06-13

5

Residence time distribution of droplets within discs and doughnuts pulsed extraction columns via Lagrangian experiments and simulations  

Microsoft Academic Search

This paper is devoted to the study of the transport of single droplets in discs and doughnuts extraction pulsed columns. Video experiments are carried out on a pilot plant of industrial size (D=300mm) in order to extract the values of the plug flow with axial dispersion transport model parameters (i.e. mean residence time and axial dispersion coefficient). The same kind

N Bardin-Monnier; P Guiraud; C Gourdon

2003-01-01

6

Use of a Pulsed Column with Discs and Crowns for Uranium Extraction from Phosphoric Acid.  

National Technical Information Service (NTIS)

The physico-chemistry of the system phosphoric acid-uranium-dioctylpyrophosphoric acid is studied for the determination of analytical methods and extraction parameters (oxidation state of uranium and iron, phosphorus concentration, extractant concentratio...

1982-01-01

7

REDISTRIBUTOR FOR LIQUID-LIQUID EXTRACTION COLUMNS  

DOEpatents

An improved baffle plate construction to intimately mix immiscible liquid solvents for solvent extraction processes in a liquid-liquid pulse column is described. To prevent the light and heavy liquids from forming separate continuous homogeneous vertical channels through sections of the column, a baffle having radially placed rectangular louvers with deflection plates opening upon alternate sides of the baffle is placed in the column, normal to the axis. This improvement substantially completely reduces strippiig losses due to poor mixing.

Bradley, J.G.

1957-10-29

8

THE VALVE-ACTUATED PULSE COLUMN DESIGN AND OPERATION  

Microsoft Academic Search

A countercurrent extraction column is described which employs timed ;\\u000a solenoid valves and pressurized feeds to provide a pulsing action to disperse the ;\\u000a phases. The steps in the pulsing cycle are independent and thus provide greater ;\\u000a separation of the operating variables than is possible with conventional pulse ;\\u000a columns. The column described is particularly useful as a resesrch

L. L. Burger; L. H. Clark

1951-01-01

9

Applicability of hydroxylamine nitrate reductant in pulse-column contactors  

SciTech Connect

Uranium and plutonium separations were made from simulated breeder reactor spent fuel dissolver solution with laboratory-sized pulse column contactors. Hydroxylamine nitrate (HAN) was used for reduction of plutonium (1V). An integrated extraction-partition system, simulating a breeder fuel reprocessing flowsheet, carried out a partial partition of uranium and plutonium in the second contactor. Tests have shown that acceptable coprocessing can be ontained using HAN as a plutonium reductant. Pulse column performance was stable even though gaseous HAN oxidation products were present in the column. Gas evolution rates up to 0.27 cfm/ft/sup 2/ of column cross section were tested and found acceptable.

Reif, D.J.

1983-05-01

10

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

11

Finite time settling control of pulsed columns  

SciTech Connect

An application of a modern control to a pulsed column is considered. Experimentally, a finite time settling control (FTSC) with finite time settling observer (FTSO) algorithms as a modern control scheme for a single-loop controller of pulsed columns was selected. The FTSC with FTSO algorithms in this study was based on the step response pattern such as the dynamic behavior for the transfer function. The control objective was to keep the solute concentration in the product stream. First, the control system was designed from the measurement data of a step response using 30% tri-n-butyl phosphate in a kerosene-acetic acid-water system. Then, the control algorithms were applied to the Purex liquid system using the published experimental data of uranium concentration during a transient operation. The controllabilities of pulsed columns are discussed in the direct digital control simulation studies.

Ikeda, Hidematsu [Univ. of Tokyo (Japan). Research Center for Nuclear Science and Technology; Katoh, Naotake [Kogakuin Univ., Tokyo (Japan)

1997-04-01

12

Identification and Control of a Liquid-Liquid Extraction Column.  

National Technical Information Service (NTIS)

This paper describes the application of two techniques (1. model control and 2. identification control method) to a liquid-liquid pulsed column for the extraction or re-extraction of uranium. Digital results achieved from simulated data are presented. The...

G. Chavent A. Poujol G. Zwingelstein

1979-01-01

13

Scale up in diameter of pulse column (axial mixing and industrial experience).  

National Technical Information Service (NTIS)

Pulse columns have been used for more than 20 years, for uranium extraction in nitric solutions by TBP knowledge acquired at the CEA leads to the development of large diameter pulse columns for processing of large quantities outside The nuclear domains. (...

A. Hanssens

1991-01-01

14

Rapid determination of theophylline in serum by selective extraction using a heated molecularly imprinted polymer micro-column with differential pulsed elution  

Microsoft Academic Search

Molecular imprinting of theophylline in poly(methacrylic acid?ethylene dimethacrylate) form binding sites with complementary size, shape and chemical functionalities to theophylline. This molecularly imprinted polymer (MIP) can be packed into a micro-column for selective solid phase extraction (SPE) of theophylline from 20 ?l of sample solution. Its chemical inertness and thermal stability allow the use of various organic solvents and elevated

Wayne M Mullett; Edward P. C Lai

1999-01-01

15

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

16

Improved operational policies for batch extractive distillation columns  

Microsoft Academic Search

The authors and others have previously developed insights into batch distillation when using a middle vessel batch column. They extended earlier work on reachable product regions for continuous columns to this and other batch column configurations. The work also examined the use of a continuously flowing extractive agent to facilitate the separation of azeotropic mixtures. A middle vessel batch column

Boyd T. Safrit; Arthur W. Westerberg

1997-01-01

17

Combined immobilized cell bioreactor and pulse column technology as a novel approach to food modification  

Microsoft Academic Search

The continuous use of an immobilized cell bioreactor (ICB) and a countercurrent pulse column is a unique approach to removing malic acid from coffee beans prior to roasting. This process recycled a high soluble solids water extract from the green coffee beans through a spiral-wound ICB loaded with food-grade bacteria (Lactobacillusspp. or Leuconostoc spp.) which metabolized malic acid in the

Geoffrey H. Bertkau; Sean M. Murphy; Frank J. Sabella

1999-01-01

18

Calculating the inventory of solvent extraction columns for material balances without shutdown  

SciTech Connect

This study demonstrates a feasible way to determine the nuclear material inventory of solvent extraction columns for calculating material balances without process shutdowns. An existing computer code, SEPHIS, was used to calculate the inventories in the solvent extraction cycles of a uranium recovery process. The applicability of the method was tested using published data on the uranium concentration profiles of solvent extraction pulse columns. The application of this method to the extraction cycles of the uranium recovery process is presented for daily uranium loss monitoring over those process units.

Brouns, R.J.; Davenport, L.C.; Richardson, G.L.

1981-07-01

19

Theoretical efficiency of pulsed polyurethane foam column separations  

Microsoft Academic Search

Two experimental arrangements of the pulsed column separation have been described and their maximum theoretical separation efficiency under optimum conditions has been investigated. It has been found that the theoretical maximum attainable separation efficiency in the closed arrangement equals the value obtained in the static (batch) one-stage separation, and in the open arrangement equals the value of the separation efficiency

Palagyi

1985-01-01

20

THEORETICAL EFFICIENCY. OF PULSED POLTURETHANE FOAM COLUMN SEPARATIONS  

Microsoft Academic Search

Two experimental arrangements of the pulsed column separation nave been described and their maximum theoretical separation efficiency under optimum conditions has been investigated. It has been found that the theoretical maximum attainable separation efficiency in the closed arrangement equals the value obtained in the static (batch) one-stage separation, and in the open arrangement equals the value of the separation efficiency

Šteían Palágyí

1985-01-01

21

Soil Vapor Extraction Column Experiments on Gasoline Contaminated Soil.  

National Technical Information Service (NTIS)

Soil vapor extraction (SVE) is a technique that is used to remove volatile organic compounds from unsaturated soils. Air is pumped through and from the contaminated zone to remove vapor phase constituents. In the work, laboratory soil column experiments w...

M. E. Miller T. A. Pedersen C. A. Kaslick G. E. Hoag C. Y. Fan

1992-01-01

22

Improved operational policies for batch extractive distillation columns  

SciTech Connect

The authors and others have previously developed insights into batch distillation when using a middle vessel batch column. They extended earlier work on reachable product regions for continuous columns to this and other batch column configurations. The work also examined the use of a continuously flowing extractive agent to facilitate the separation of azeotropic mixtures. A middle vessel batch column has both an enriching and stripping section and thus both a distillate and bottoms product. In many ways it is just like a traditional continuous column, but the authors feed it by charging a middle tray having a very large holdup (a pot or still) with the initial feed. The work compared running this column with running a batch rectifier for an azeotropic mixture when using an extractive agent. They showed that both are often able in theory to recover all of the distillate component in relatively pure form, with the middle vessel accomplishing this by steering the still pot composition against time through the choice of reflux, reboil, entrainer, and product rates. The middle vessel also requires a much smaller pot, as the authors can continually remove and recycle the extractive agent. In this work the authors show the sensitivity of the separation`s profit to the entrainer flow rate, the operation`s switching times between fractions, and the bottom flow rate policy for an extractive middle vessel batch column. They illustrate with an example problem.

Safrit, B.T.; Westerberg, A.W. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

1997-02-01

23

A new model for solvent extraction in columns  

SciTech Connect

A new model was developed for analyzing solvent extraction processes carried out in columns. Each column is treated as a series of well-defined equilibrium stages where the backmixing (other-phase carryover) between stages can be large. By including all mass transfer effects in the backmixing value, the same number of stages can be used for all extracted components no matter what their distribution coefficients. This greatly simplifies the calculations required when modeling multicomponent solvent extraction processes. Initial testing shows the new model to be better than either the Height of an Equivalent Theoretical Plate (HETP) or the Height of a Transfer Unit (HTU) method.

Leonard, R.A.; Regalbuto, M.C.; Chamberlain, D.B.; Vandegrift, G.F.

1989-12-08

24

Using solvent extraction to process nitrate anion exchange column effluents  

SciTech Connect

Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO), a new organophosphorous extractant, and a new centrifugal mixer-settler both recently developed at Argonne were evaluated for their potential use in the recovery of actinides from nitrate anion exchange column effluents. The performance of the extractant was evaluated by measuring the extraction coefficient values as a function of acid and salt concentration. Additional performance parameters include extraction coefficient behavior as a function of the total metal concentration in the organic phase, and comparison of different stripping and organic scrubbing techniques. A simulated effluent stream was used to evaluate the performance of the centrifugal mixer-settlers by comparing experimental and calculated interstage concentration profiles. Both the CMPO extractant and the centrifugal mixer-settlers have potential for processing nitrate column effluents, particularly if the stripping behavior can be improved. Details of the proposed process are presented in the flowsheet and contactor design analyses.

Yarbro, S.L.

1987-10-01

25

Dynamic and Steady State Behaviour of an Extractive Distillation Column  

Microsoft Academic Search

This project was the second part of a long-term study into the control of an extractive distillation unit. A fifteen stage extractive distillation column was re-built and operated over a range of operating levels. Overhead product acetone composition was limited to approximately 0.94 mole fraction acetone due to tray liquid priming. A steady state simulation was developed to aid in

Dwayne L. ONeill

1975-01-01

26

SOIL VAPOR EXTRACTION COLUMN EXPERIMENTS ON GASOLINE CONTAMINATED SOIL  

EPA Science Inventory

Soil vapor extraction (SVE) is a technique that is used to remove volatile organic compounds from unsaturated soils. ir is pumped through and from the contaminated zone to remove vapor phase constituents. n this work, laboratory soil column experiments were conducted using a gaso...

27

SOIL VAPOR EXTRACTION COLUMN EXPERIMENTS ON GASOLINE CONTAMINATED SOIL  

EPA Science Inventory

Soil vapor extraction (SVE) is a technique that is used to remove volatile organic compounds from unsaturated soils. Air is pumped through and from the contaminated zone to remove vapor phase constituents. In the work, laboratory soil column experiments were conducted using a gas...

28

COLUMN VAPOR EXTRACTION EXPERIMENTS ON GASOLINE CONTAMINATED SOIL  

EPA Science Inventory

Soil vapor extraction (SVE) is a technique that is used to remove volatile organic compounds from unsaturated soils. ir is pumped from the contaminated area and the chemicals are removed from the resulting vapor stream. n this work laboratory, soil column experiments were conduct...

29

Scale-up procedures for a Scheibel extraction column  

SciTech Connect

This report presents a summary of the equations and relationships used to scale-up a Scheibel liquid-liquid countercurrent extractor column. These equations were obtained by using (1) certain assumptions deemed appropriate when treating process condensates from fixed-bed gasifiers and (2) published relationships specific to the scale-up of Scheibel columns. The scale-up procedure is based upon the removal of a key component using a polar solvent (single solvent extraction). Data were obtained from the GFETC pilot (6 inch diameter) column to generate an example scale-up calculation. The calculation used phenol as the key component. The solvent was diisopropyl ether (DIPE). The operation of the GFETC column serves to indicate that differential contactors may be used to effectively treat gasifier process condensates. To size (and cost) a large-scale unit, however, does require data generated from the specific type of unit to be used. Thus, the scale-up equations presented are specific to the Scheibel column. This scale-up procedure generates approximate dimensions and power requirements for the conceptual commercial-scale Scheibel extractor. The results can be used in rough cost estimates and in comparative studies with other conceptual large-scale extractor types (e.g. mixer-settlers) in order to select the most cost-efficient design(s).

Not Available

1983-06-03

30

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

31

Electron Drift Speed and Multiplication in a Pulsed Positive Column.  

National Technical Information Service (NTIS)

A method of studying electron drift speed and electron multiplication rate in a positive column is described. A steady-state low-current glow discharge is subjected to a sudden increase in the axial electric field and the subsequent growth of the current ...

C. H. H. Carmichael

1971-01-01

32

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

33

Analyse du fonctionnement hydrodynamique d'une colonne pulsee a disques et couronnes. (Hydrodynamic operation analysis of a pulse with disks and rings column).  

National Technical Information Service (NTIS)

The aim of this work is to analyse the measurements of the pressure sensors of a pulse liquid-liquid extraction column and to improve the understanding of its hydraulic behaviour. The first part studies the average differential pressure measurements. The ...

J. F. Milot

1990-01-01

34

Simultaneous extraction of six pesticides using a dual-column extraction procedure  

SciTech Connect

A method was developed that allowed for the simultaneous extraction of six pesticides (three chloro-s-triazines, a substituted amide, an organic phosphate, and a benzoic acid derivative) from either sod or water samples. This rnethod utilizes two types of solid-phase extraction columns, one reverse phase, and one anion exchange column, connected in series to extract all six compounds from a single sample. After separate elution of the two columns, high pressure liquid chromatography was employed to analyze the benzoic acid derivative utilizing a C-18 column and paired Ion techniques with a detection limit of 6 {mu}g L{sup -1}. A gas chromatography equipped with a N-P detector, was used to analyze the remaining five compounds. The detectable limit for the chloro-s-triazines was 3 {mu}g L{sup -1} while the detection limit of the substituted amide was 6 {mu}g L{sup -1}. 11 refs., 1 fig., 1 tab.

Watts, D.W.; Bogus, E.R.; Hall, J.K.; Mumma, R.O. [Coastal Plains Research Center, Florence, SC (United States)

1994-03-01

35

Consolidated Fuel Reprocessing Program. Operating experience with pulsed-column holdup estimators  

SciTech Connect

Methods for estimating pulsed-column holdup are being investigated as part of the Safeguards Assessment task of the Consolidated Fuel Reprocessing Program (CFRP) at the Oak Ridge National Laboratory. The CFRP was a major sponsor of test runs at the Barnwell Nuclear Fuel plant (BNFP) in 1980 and 1981. During these tests, considerable measurement data were collected for pulsed columns in the plutonium purification portion of the plant. These data have been used to evaluate and compare three available methods of holdup estimation.

Ehinger, M.H.

1986-01-01

36

Rapid Actinide Column Extraction Methods for Bioassay Samples  

SciTech Connect

A new, rapid separation method to assay actinides in urine samples has been developed at the Westinghouse Savannah River Site (SRS). The new method separates plutonium, neptunium, uranium, americium and strontium-90 with high chemical recovery and excellent thorium removal. The method uses calcium phosphate precipitation and stacked TEVA Resin(R) and TRU Resin(R) cartridges to separate and purify the actinides. Plutonium and neptunium are separated on TEVA Resin(R), while uranium and americium are simultaneously retained and separated on TRU Resin(R). Plutonium-236 tracer can be used to allow simultaneous separation and measurement of both plutonium and neptunium using TEVA Resin(R). Strontium-90 can also be separated on Sr Resin(R) by evaporating and redissolving load and rinse solutions collected from the TEVA/TRU column and separating strontium on Sr-Resin(R). Fast flow rates are achieved by using small particle size resin cartridges and a vacuum box separation system that will separate 24 samples at a time. This unique approach can be used with urine samples because iron is not present at significant levels in urine and plutonium reduction is accomplished without adding iron (II) to the sample. The advantage of this approach is that actinides can be loaded onto two separate resins in a single load step with simultaneous extraction and assay of neptunium and plutonium with high chemical recovery and excellent removal of matrix interferences.

Maxwell, S.L.

2003-01-14

37

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.

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

2013-01-01

38

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

PubMed

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

2013-09-24

39

Fuzzy Extraction System for Heart Pulse by Air Pressure Sensor  

Microsoft Academic Search

In this paper, we detect a pressure change of vital information and a heart pulse using an air pressure sensor. We could detect the heart pulse at higher S\\/N ratio for the various positions using an air pressure sensor. As the result for live volunteers, we could extract the heart pulse at the 1.28% error ratio. In the temporal transitional

Y. Kamozaki; T. Sawayama; K. Taniguchi; S. Kobashi; K. Kondo; Y. Hata

2006-01-01

40

Scale-Up Procedures for a Scheibel Extraction Column.  

National Technical Information Service (NTIS)

This report presents a summary of the equations and relationships used to scale-up a Scheibel liquid-liquid countercurrent extractor column. These equations were obtained by using (1) certain assumptions deemed appropriate when treating process condensate...

1983-01-01

41

Extraction of solanesol from tobacco ( Nicotiana tobaccum L.) leaves by bubble column  

Microsoft Academic Search

An extraction method, namely bubble column extraction (BCE), was developed for the rapid and efficient extraction of solanesol from tobacco leaves. Liquid chromatography–tandem mass spectrometry (LC–MS\\/MS) was used for qualitative analysis and the reverse phase high performance liquid chromatography (HPLC) was used for quantification analysis. Several parameters, such as extraction solvent, particle size of sample, extraction time, liquor to material

Chunjian Zhao; Yuangang Zu; Chunying Li

2009-01-01

42

Vapor transport in unsaturated soil columns: Implications for vapor extraction  

Microsoft Academic Search

A mathematical model was derived to examine the impact of gas advection, gas diffusion, gas-water mass transfer, gas-water partitioning, sorption, and intraaggregate diffusion on subsurface movement of organic vapors. Laboratory experiments were performed to determine the validity of the model and to investigate the impact of the various mechanisms on vapor transport. Columns were packed with a uniform Ottawa sand

John S. Gierke; Neil J. Hutzler; David B. McKenzie

1992-01-01

43

Hydrodynamics of a packed countercurrent column for the gas extraction  

SciTech Connect

The hydraulic capacity of a countercurrent column with gauze packing was examined at pressures between 8 and 30 MPa and temperatures between 313 and 373 K. The systems used were water + carbon dioxide, aqueous surfactant solution + carbon dioxide, and Toco, a substance whose physical properties are roughly similar to those of {alpha}-Tocopherol + carbon dioxide. A distinctive change in the flooding mechanisms from liquid layer flooding to bubble column flooding was observed. The different liquids, water and Toco, showed the same flooding behavior, indicating that the influence of the density on the flooding behavior prevails over the influence of any other physical property of the liquid. The foamability of the surfactant solution decreased significantly with increasing pressure--its influence on the flooding behavior could not be proved. The liquid holdup ranged between 2% and 6%. The dry pressure drop adhered to the Ergun equation.

Stockfleth, R.; Brunner, G.

1999-10-01

44

Cost/performance comparison between pulse columns and centrifugal contactors designed to process Clinch River Breeder Reactor fuel  

SciTech Connect

A comparison between pulse columns and centrifugal contactors was made to determine which type of equipment was more advantageous for use in the primary decontamination cycle of a remotely operated fuel reprocessing plant. Clinch River Breeder Reactor (CRBR) fuel was chosen as the fuel to be processed in the proposed 1 metric tonne/day reprocessing facility. The pulse columns and centrifugal contactors were compared on a performance and total cost basis. From this comparison, either the pulse columns or the centrifugal contactors will be recommended for use in a fuel reprocessing plant built to reprocess CRBR fuel. The reliability, solvent exposure to radiation, required time to reach steady state, and the total costs were the primary areas of concern for the comparison. The pulse column units were determined to be more reliable than the centrifugal contactors. When a centrifugal contactor motor fails, it can be remotely changed in less than one eight hour shift. Pulse columns expose the solvent to approximately five times as much radiation dose as the centrifugal contactor units; however, the proposed solvent recovery system adequately cleans the solvent for either case. The time required for pulse columns to reach steady state is many times longer than the time required for centrifugal contactors to reach steady state. The cost comparison between the two types of contacting equipment resulted in centrifugal contactors costing 85% of the total cost of pulse columns when the contactors were stacked on three levels in the module. If the centrifugal contactors were all positioned on the top level of a module with the unoccupied volume in the module occupied by other equipment, the centrifugal contactors cost is 66% of the total cost of pulse columns. Based on these results, centrifugal contactors are recommended for use in a remotely operated reprocessing plant built to reprocess CRBR fuel.

Ciucci, J.A. Jr.

1983-12-01

45

On-Line Control of a Liquid-Liquid Extraction Column by the Modal Control Method.  

National Technical Information Service (NTIS)

The application of modal analysis to the on-line control of a liquid-liquid extraction column is presented. This process is used in reprocessing for U purification. U in the aqueous acid phase is extracted by a solvent flowing at counter-current. The proc...

P. Bonnefoi A. Poujol G. Zwingelstein C. Dargier H. Rouyer

1977-01-01

46

Fingerprint development for Ginkgo biloba extracts by pressurized capillary electrochromatography: comparison of column types.  

PubMed

A pressurized capillary electrochromatographic (pCEC) fingerprint of Ginkgo biloba leaf extract was developed on three different types of capillary columns. A commercial column packed with 3-microm particles and an in-house column packed with 5-microm particles were investigated for their performance. Additionally, a monolithic column was included in the fingerprint study as a potential alternative to the conventional packed columns. The effects of experimental parameters, such as the composition of the mobile phase, the concentration and pH of the buffer, and the applied voltage, were studied. Binary mobile phases consisting of acetonitrile and a 5 mM sodium dihydrogen phosphate electrolyte at pH 2.8 were used in gradient elution mode with an applied voltage of 5 kV. Under optimal gradient conditions, at least 45 peaks were observed within 60 min on the commercial packed column, whereas only about 20 peaks were separated on the methacrylate-based monolithic and the in-house packed columns. The commercial column thus clearly outperforms the two other. However, the properties of the monolithic stationary phase still might be adapted (i.e., by changing the polymerization-mixture composition, the porosity, and thus the selectivity of the phase might be changed), which could lead to an improved efficiency. PMID:20822655

Wang, Jiajing; Tanret, Indiana; Mangelings, Debby; Fan, Guorong; Wu, Yutian; Vander Heyden, Yvan

2010-07-01

47

Time Transients of Roto-Vibrational Energy Distribution in Positive Column of Pulsed Nitrogen Discharge  

NASA Astrophysics Data System (ADS)

Time transients of energy stored in vibrational/rotational motion of molecular nitrogen in the ground electronic state were measured in a positive column of pulsed discharge. Discharge was operating at peak current densities up to 25 A/cm^2, pressures up to 6 Torr and pulse duration between 1.0 and 3.0 ?s . The measurements were done during the active discharge and in the afterglow. Coherent Anti-Stokes Raman Spectroscopy (CARS) in unstable-resonator spatially enhanced detection (USED) geometry was employed in all measurements. The 30 GHz line width of Nd-YAG laser set the limit on spectral resolution. The resolution was insufficient to observe single roto-vibrational lines. The energy stored in rotational motion was inferred from the width of vibrational bands. It is shown that initially energy is being transfer, primarily into vibrational levels above v=1, resulting in a highly non Boltzmann distribution. The redistribution between vibrational levels takes place within 100 ?s after the discharge pulse. The rotational temperature was as high as 4000 K and reached maximum values between 80 and 100 ?s after the discharge pulse.

Borysow, Jacek

1998-10-01

48

Stability of hydrocarbon samples n solid-phase extraction columns  

SciTech Connect

The stability of hydrocarbon samples sorbed from water onto two types of solid phases was examined. The two solid phases, XAD-2 macroreticular resin and octadecane bonded on silica gel, were found to have a preservative effect which prevented the breakdown of sorbed hydrocarbons by bacteria. Hydrocarbons stored on these solid phases for periods of up to 100 days in the presence of an oleophilic bacterial population showed no evidence of biological degradation as indicated by changes in chromatographic pattern or degradation of a radiolabeled hydrocarbon. In contrast, hydrocarbons stored in water samples containing the same bacteria showed pronounced degradation over much shorter storage periods. The macroreticular or pore structure of the solid phases is thought to be the mechanism by which the extracted hydrocarbons are preserved from bacterial attack.

Green, D.R.; Le Pape, D.

1987-03-01

49

The setup of an extraction system coupled to a hydrogen isotopes distillation column  

SciTech Connect

Among the most difficult problems of cryogenic distillation one stands apart: the extraction of the heavy fraction. By an optimal design of the cycle scheme, this problem could be avoided. A 'worst case scenario' is usually occurring when the extracted fraction consists of one prevalent isotope such as hydrogen and small amounts of the other two hydrogen isotopes (deuterium and/or tritium). This situation is further complicated by two parameters of the distillation column: the extraction flow rate and the hold-up. The present work proposes the conceptual design of an extraction system associated to the cryogenic distillation column used in hydrogen separation processes. During this process, the heavy fraction (DT, T{sub 2}) is separated, its concentration being the highest at the bottom of the distillation column. From this place the extraction of the gaseous phase can now begin. Being filled with adsorbent, the extraction system is used to temporarily store the heavy fraction. Also the extraction system provides samples for the gas Chromatograph. The research work is focused on the existent pilot plant for tritium and deuterium separation from our institute to validate the experiments carried out until now. (authors)

Zamfirache, M.; Bornea, A.; Stefanescu, I.; Bidica, N.; Balteanu, O.; Bucur, C. [INC-DTCI, ICSIRm. Valcea, Uzinei Street 4, Rm. Valcea (Romania)

2008-07-15

50

Integration of reaction and separation in a batch extractive distillation column with a middle vessel  

Microsoft Academic Search

In this work, the integration of reaction and separation in a batch extractive distillation column with a middle vessel\\/reactor is analyzed for azeotrope-forming mixtures. This equipment configuration has the potential to promote complete conversion of reactants and therefore, the main process characteristics are investigated. A mixture showing several azeotropes and suffering an esterification reaction was selected as an academic example.

José Espinosa

2002-01-01

51

Practical Application of the Modal Control Theory to a Liquid Liquid Extraction Column.  

National Technical Information Service (NTIS)

Modal control theory is applied to the regulation of a liquid-liquid extraction column used in a nuclear fuel reprocessing plant. The mathematical model of the process is a set of four non-linear partial differential equations. The unknown parameters are ...

P. Bonnefoi A. Poujol G. Zwingelstein C. Dargier H. Rouyer

1977-01-01

52

Feature Extraction for Pulse Waveform in Traditional Chinese Medicine by Hemodynamic Analysis  

Microsoft Academic Search

Pulse diagnosis is one of important diagnosis methods in Traditional Chinese Medicine (TCM). Feature extraction of TCM pulse has received more and more attention in recent years. While most of previous methods for feature extraction of TCM pulse have no specific correlation with the mechanism of TCM pulse, a hemodynamics method was used to calculate the pulse waveform velocity (PWV)

Haixia Yan; Yiqin Wang; Zhaorong Liu; Rui Guo; Fufeng Li; Fengying Run; Yujian Hong

2009-01-01

53

[Preparation and applications of a supported liquid-liquid extraction column with a composite diatomite material].  

PubMed

A rapid and special supported liquid-liquid extraction (SLE) column was developed with a composite diatomite material. The SLE column was evaluated by high performance liquid chromatography (HPLC) with acidic, neutral and alkaline compounds dissolved in water. Furthermore, some real complex samples were also analyzed by HPLC with the SLE method. The recoveries of benzoic acid (acidic), p-nitroaniline (alkaline) and 4-hydroxy-benzoic methyl ester (neutral) treated by the SLE column were 90.6%, 98.1% and 97.7%. However, the recoveries of the three compounds treated by traditional liquid-liquid extraction (LLE) method were 71.9%, 81.9% and 83.9%. The results showed that the SLE technique had higher recoveries than the traditional LLE method. The spiked recoveries of the complex samples, such as benzoic acid in Sprite and dexamethasone acetate, chlorphenamine maleate, indomethacin in bovine serum, were between 80% and 110% and the relative standard deviations (RSDs) were less than 15%. For biological specimen, the results could be accepted. Meantime, many disadvantages associated with traditional LLE method, such as emulsion formation, didn't occur using SLE column. The SLE column technique is a good sample preparation method with many advantages, such as rapid, simple, robust, easily automated, high recovery and high-throughput, which would be widely used in the future. PMID:23256382

Bao, Jianmin; Ma, Zhishuang; Sun, Ying; Wang, Yongzun; Li, Youxin

2012-08-01

54

Ni(II) ion-imprinted solid-phase extraction and preconcentration in aqueous solutions by packed-bed columns  

Microsoft Academic Search

Solid-phase extraction (SPE) columns packed with materials based on molecularly imprinted polymers (MIPs) were used to develop selective separation and preconcentration for Ni(II) ion from aqueous solutions. SPE is more rapid, simple and economical method than the traditional liquid–liquid extraction. MIPs were used as column sorbent to increase the grade of selectivity in SPE columns. In this study, we have

Arzu Ersöz; R?dvan Say; Adil Denizli

2004-01-01

55

Determination of borate in extracts of gypsiferous soils by single column ion chromatography  

Microsoft Academic Search

A high performance liquid chromatography apparatus with a resin based anion exchange column and a conductivity detector were used to develop a method for borate separation and quantification in extracts of gypsiferous soils. An eluant containing 5 mMNaOH and 0.5 mMNa?benzoate was found to produce satisfactory chromato?grams. Calibration curves were linear in the range l to 7 mg B\\/L. The

L. M. Dudley

1989-01-01

56

The enrichment of n?3 polyunsaturated fatty acids using aminopropyl solid phase extraction columns  

Microsoft Academic Search

A rapid, simple and reliable method is described for the preparation of concentrates of methyl or ethyl esters of n?3 polyunsaturated\\u000a fatty acids by solid phase extraction using aminopropyl bonded silica columns. After applying mixtures of fatty acid esters\\u000a in hexane, saturated and monounsaturated fatty acid esters are preferentially eluted with hexane whereas polyunsaturated fatty\\u000a acids (PUFA) can subsequently be

Robert Wilson; R. James Henderson; Ivan C. Burkow; John R. Sargent

1993-01-01

57

Combined extraction-cleanup column chromatographic procedure for determination of dicofol in avian eggs  

USGS Publications Warehouse

Dicofol in avian eggs was completely oxidized to dichlorobenzophenone (DCBP) when a hexane Soxhlet extraction procedure was used. This degradation did not occur with other avian tissues (muscle and liver). For this reason, a combined extraction-cleanup column chromatographic procedure, without added heat, was developed for the determination of dicofol in avian eggs. Homogenized subsamples of eggs were mixed with sodium sulfate, and the mixture was added as the top layer on a column prepacked with Florisil. The dicofol and other compounds of interest were then eluted with ethyl ether-hexane. The extracts, relatively free from lipids, were quantitated on a gas chromatograph equipped with a 63Ni electron-capture detector and a methyl silicone capillary column. Recoveries from chicken eggs, fortified with dicofol and other DDT-related compounds, averaged 96%. Analysis of eggs of eastern screech-owls, fed a meat diet containing 10 ppm technical Kelthane, showed that both dicofol and DCBP were present. Results were confirmed by gas chromatography/mass spectrometry. This method is rapid and reliable, involves a minimum of sample handling, and is well suited for high volume determination of dicofol in eggs and other avian tissues.

Krynitsky, A.J.; Stafford, C.J.; Wiemeyer, S.N.

1988-01-01

58

Feature extraction and recognition for pulse waveform in Traditional Chinese Medicine based on hemodynamics principle  

Microsoft Academic Search

Pulse diagnosis is one of important diagnosis methods in Traditional Chinese Medicine (TCM). Recognition of TCM pulse has received more and more attention in recent years. Extracting proper features is crucial for satisfactory classification. While most of previous methods for feature extraction of TCM pulse have no specific correlation with the mechanism of TCM pulse, a hemodynamics method is used

Hai Xia Yan; Yi Qin Wang; Rui Guo; Zhao Rong Liu; Fu Feng Li; Feng Ying Run; Yu Jian Hong; Jian Jun Yan

2010-01-01

59

Eddy current pulsed phase thermography and feature extraction  

NASA Astrophysics Data System (ADS)

This letter proposed an eddy current pulsed phase thermography technique combing eddy current excitation, infrared imaging, and phase analysis. One steel sample is selected as the material under test to avoid the influence of skin depth, which provides subsurface defects with different depths. The experimental results show that this proposed method can eliminate non-uniform heating and improve defect detectability. Several features are extracted from differential phase spectra and the preliminary linear relationships are built to measure these subsurface defects' depth.

He, Yunze; Tian, GuiYun; Pan, Mengchun; Chen, Dixiang

2013-08-01

60

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

2011-11-30

61

Recent Pulsed Airborne Lidar measurements of Atmospheric CO2 Column Absorption to 13 km altitudes  

NASA Astrophysics Data System (ADS)

We have developed a lidar technique for measuring atmospheric CO2 concentrations as a candidate for NASA’s ASCENDS mission. It uses pulsed laser transmitters to simultaneously measure a CO2 absorption line in the 1570 nm band, O2 extinction in the Oxygen A-band and surface height and backscatter. The lidar measures the energy and time of flight of the laser echoes reflected from the atmosphere and surface. The lasers step in wavelength across the CO2 line and an O2 line pair during the measurement. The receiver uses a telescope and photon counting detectors, and measures the time resolved backscatter of the laser echoes. Signal processing is used to isolate the laser echo signals from the surface, estimate their range, and reject laser photons scattered in the atmosphere. The gas extinction and column densities for the CO2 and O2 gases are estimated via the IPDA technique. We developed a lidar to demonstrate the CO2 measurement from aricraft. The lidar steps the pulsed laser’s wavelength across a selected CO2 line with 20 or 30 steps per scan. The line scan rate is 450 Hz and laser pulse widths are 1 usec. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a photomultiplier and is recorded by a photon counting system. During July and August 2009 we made 5 two hour long flights while installed on the NASA Glenn Lear-25 aircraft. We 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 a variety of surfaces in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay. Strong laser signals and clear line shapes were observed at all altitudes, and some measurements were made through thin clouds. The Oklahoma and east coast flights were coordinated with the NASA LaRC/ITT CO2 lidar on their UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. Ed Browell and Gary Spiers led the LaRC and JPL teams. In 2010 we improved the CO2 lidar by increasing the number of wavelength samples and extending the receiver sensitivity and dynamic range. We also added a new oxygen lidar channel, which measures the absorption spectrum of an O2 line doublet near 764.7 nm using the pulsed IPDA technique. We integrated the dual wavelength lidar onto the NASA DC-8 aircraft and in July 2010 participated in the NASA ASCENDS field campaign. This flew 5 science flights over the central valley of California, several desert areas, over the Pacific Ocean, and over the DOE SGP ARM site. Clear CO2 line shapes, which changed as expected with range and altitude, were observed on all flights. Clear Oxygen absorption spectra, which deepened with altitude, were recorded on the last few flights to 13 km altitudes. Both sets of absorption measurements are currently being analyzed and compared to calculations utilizing readings from radiosondes and in-situ gas sensors on the aircraft. Details of the flights, measurements and analysis will be described in the presentation.

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

2010-12-01

62

Application of polydivinylbenzene liquid chromatography columns to remove lipid material from fish tissue extracts for the analysis of semivolatile organics.  

PubMed

Liquid chromatography columns of 100% polydivinylbenzene (DVB) (packing) were used to remove lipid material from fish extracts before analysis of several semivolatile organic pollutants by gas chromatography-mass spectrometry (GC-MS). This packing material was found to be durable as the columns could be operated to about 900 p.s.i. resulting in high efficiency separation. Recoveries and relative standard deviations for 18 polynuclear aromatic hydrocarbons fortified into a fish extract and cleaned up by multiple DVB columns in series were in the range of 86 to 123% and 4 to 11%, respectively. PMID:10574216

Dodo, G H; Knight, M M

1999-10-29

63

On-line extraction of polymers, oligomers, additives and monomers by multiple solvents on packed HPLC columns  

Microsoft Academic Search

Extraction of monomers, additives, oligomers, and polymers from a blend is very time consuming and labor intensive. Now by use of a special guard column and multi-solvent gradient liquid chromatograph (HPLC), the extraction and analysis can be performed in one step.

W. J. Staal; PJCH Cools; A. M. van Herk; A. L. German

1993-01-01

64

Application of polydivinylbenzene liquid chromatography columns to remove lipid material from fish tissue extracts for the analysis of semivolatile organics  

Microsoft Academic Search

Liquid chromatography columns of 100% polydivinylbenzene (DVB) (packing) were used to remove lipid material from fish extracts before analysis of several semivolatile organic pollutants by gas chromatography–mass spectrometry (GC–MS). This packing material was found to be durable as the columns could be operated to about 900 p.s.i. resulting in high efficiency separation. Recoveries and relative standard deviations for 18 polynuclear

Gerald H Dodo; Margaret M Knight

1999-01-01

65

Physical versus chemical effects on bacterial and bromide transport as determined from on site sediment column pulse experiments  

Microsoft Academic Search

Twenty-eight bacterial and Br transport experiments were performed in the field to determine the effects of physical and chemical heterogeneity of the aquifer sediment. The experiments were performed using groundwater from two field locations to examine the effects of groundwater chemistry on transport. Groundwater was extracted from multilevel samplers and pumped through 7-cm-long columns of intact sediment or repacked sieved

James A. Hall; Brian J. Mailloux; Tullis C. Onstott; Timothy D. Scheibe; Mark E. Fuller; Hailiang Dong; Mary F. Deflaun

2005-01-01

66

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

67

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

2011-04-08

68

Determination of commonly used herbicides in surface water using solid-phase extraction and dual-column HPLC-DAD.  

PubMed

The present study describes the application of different solid-phase extraction techniques for the extraction, separation, and quantitative determination of 10 commonly used herbicides with different chemical structures (chlorsulfuron, diuron, bentazone, linuron, chlorpropham, fenoxoprop-ethyl, MCPA, diclofop-methyl, fluazifop-butyl, trifluraline) in water. Octadecyl (C(18)) Empore extraction disks, octadecyl (C(18)), and stryene divinylbenzene (SDB) Bond Elut Env cartridges were compared for solid-phase extraction efficiency. Herbicides were separated and quantified by reversed-phase high performance liquid chromatography with diode-array detection (HPLC-DAD) with simultaneous separation on two columns of differing polarity (C(18) and CN) to confirm identification. Analytical separation was performed simultaneously on C(18) and CN columns. Reanalysis of the sample extracts on a (cyano) CN column were used to confirm the identity of these compounds. Method optimization and validation parameters were presented in this work. Recoveries varied from 76.0% to 99.0% for C(18) disks, from 75.1% to 100.0% for C(18) cartridges, and from 54.0% to 98.0% for SDB cartridges over concentrations at 0.025--0.4 microg L(-1). The limits of detection were 0.012--0.035 microg L(-1). PMID:16194920

Ozhan, Gül; Ozden, Sibel; Alpertunga, Buket

2005-01-01

69

Pulsed ion extraction diagnostics in a quadrupole ion trap linear time-of-flight mass spectrometer  

NASA Astrophysics Data System (ADS)

Pulsed extraction techniques are investigated for a quadrupole ion trap (QIT) interfaced to a linear time-of-flight (TOF) mass analyzer. A nonfocusing short-pulse mode of operation is developed and characterized. The short-pulse mode creates a near-monoenergetic ion packet, which is useful for reaction kinetics experiments and for making diagnostic measurements of the ion cloud size in the trap. Monopolar and bipolar pulsing modes, with the voltage pulses applied to one or both QIT endcaps to extract the ions into the TOF region, are compared. Ion TOF peak distributions are characterized experimentally and by ion trajectory simulations. Also, first-order spatial (Wiley-McLaren) focusing of ions is characterized for the conventional long-pulse extraction mode. The nonparallel fields in the QIT, which serves as the first acceleration region in the linear-TOF mass spectrometer, are shown to degrade spatial focusing and mass resolution.

Dangi, Beni B.; Sassin, Nicholas A.; Ervin, Kent M.

2010-06-01

70

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

71

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

72

Comparative study between extraction techniques and column separation for the quantification of sinigrin and total isothiocyanates in mustard seed.  

PubMed

Glucosinolates are ?-thioglycosides which are found naturally in Cruciferae including the genus Brassica. When enzymatically hydrolysed, glucosinolates yield isothiocyanates and give a pungent taste. Both glucosinolates and isothiocyanates have been linked with anticancer activity as well as antifungal and antibacterial properties and therefore the quantification of these compounds is scientifically important. A wide range of literature exists on glucosinolates, however the extraction and quantification procedures differ greatly resulting in discrepancies between studies. The aim of this study was therefore to compare the most popular extraction procedures to identify the most efficacious method and whether each extraction can also be used for the quantification of total isothiocyanates. Four extraction techniques were compared for the quantification of sinigrin from mustard cv. Centennial (Brassica juncea L.) seed; boiling water, boiling 50% (v/v) aqueous acetonitrile, boiling 100% methanol and 70% (v/v) aqueous methanol at 70 °C. Prior to injection into the HPLC, the extractions which involved solvents (acetonitrile or methanol) were freeze-dried and resuspended in water. To identify whether the same extract could be used to measure total isothiocyanates, a dichloromethane extraction was carried out on the sinigrin extracts. For the quantification of sinigrin alone, boiling 50% (v/v) acetonitrile was found to be the most efficacious extraction solvent of the four tested yielding 15% more sinigrin than the water extraction. However, the removal of the acetonitrile by freeze-drying had a negative impact on the isothiocyanate content. Quantification of both sinigrin and total isothiocyanates was possible when the sinigrin was extracted using boiling water. Two columns were compared for the quantification of sinigrin revealing the Zorbax Eclipse to be the best column using this particular method. PMID:22743340

Cools, Katherine; Terry, Leon A

2012-06-01

73

Kinetics of Rb formation from RbCl in the positive column of the hydrogen-pulsed discharge  

NASA Astrophysics Data System (ADS)

Time transients of the number densities of Rb in the ground electronic state were measured in a positive column of moderate-current hydrogen-pulsed discharge. Atomic rubidium was formed by dissociation of RbCl. The population of Rb was monitored by high resolution laser absorption. The laser was tuned to one of the D2 transitions near 780 nm. Experiments were done at hydrogen number densities from 6.4 × 1015 to 9.6 × 1016 cm-3 and current densities ranging from 0.1 to 0.5 A cm-2. Number densities of RbCl varied from 4.0 × 105 to 3.0 × 107 cm-3. The kinetic model in the form of rate equations reproduces closely measured time transients of the Rb population. The model assumes that the primary mechanism for the production of atomic rubidium is the chemical reaction RbCl + H ? Rb + HCl.

Pakhomov, Andrew V.; Borysow, Jacek

2007-02-01

74

SCALEUP AND PERFORMANCE OF 5 FT. (1.52 m) DIAMETER RECIPROCATING PLATE EXTRACTION COLUMN  

Microsoft Academic Search

Environmental considerations dictated the necessity of reducing the phenol content of a waste water to less than 1 PPM. Tests were conducted in a 2 inch diameter column and the test column was optimized with respect to plate spacing and volumetric efficiency. The production unit, scaled up from the test unit, was 5 ft. in diameter. Waste water levels of

A. E. Karr; S. Ramanujam

1988-01-01

75

In vivo biotransformation of metoprolol in the horse and on-column esterification of the aminocarboxylic acid metabolite by alcohols during solid phase extraction using mixed mode columns.  

PubMed

The in vivo biotransformation of metoprolol tartrate in the thoroughbred racehorse was studied after administration of a single oral dose. Metoprolol and its basic and bifunctional phase I metabolites were isolated from urine and plasma using mixed mode solid phase extraction (SPE) cartridges. The isolates were derivatised as trimethylsilyl ethers and analysed by capillary column gas chromatography--positive ion electron ionisation and ammonia chemical ionisation mass spectrometry. Metabolism was primarily confined to the oxidative transformations of the p-(2-methoxy)ethyl substituent. Metoprolol and five phase I metabolites were detected in horse urine. In common with man, rat and dog, the zwitterionic compound (+/-)-4-(2-hydroxy-3-isopropylaminopropoxy)-phenylacetic acid (H117/04), was the principle metabolite in the horse. This compound was readily isolated from both plasma and urine samples by SPE and, in addition, an unusual on-column esterification of the carboxylic acid moiety by alcohols was observed. Metoprolol and the major aliphatic acid metabolite were detected for about 10 and 40 h, respectively in unhydrolysed urine. After enzymatic hydrolysis, the detection period increased to 15 and 60 h, respectively indicating some phase II metabolism of metoprolol and its metabolites in the horse. PMID:16168607

Dumasia, M C

2005-09-15

76

Pulsed Airborne Lidar measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km altitudes  

NASA Astrophysics Data System (ADS)

We have developed a pulsed lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA's planned ASCENDS space mission. Our technique uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1570 nm band, O2 extinction in the Oxygen A-band and surface height and backscatter. The lidar measures the energy and time of flight of the laser echoes reflected from the atmosphere and surface. The lasers are rapidly and precisely stepped in wavelength across the CO2 line and an O2 line region during the measurement. The direct detection receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. Time gating is used to isolate the laser echo signals from the surface, and to reject laser photons scattered in the atmosphere. The time of flight of the laser pulses are also used to estimate the height of the scattering surface and to identify cases of mixed cloud and ground scattering. We have developed an airborne lidar to demonstrate the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar steps the pulsed laser's wavelength across the selected CO2 line with 20 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 photomultiplier and is recorded by a photon counting system. We made initial airborne measurements on flights during fall 2008. Laser backscatter and absorption measurements were made over a variety of land and water surfaces and through thin clouds. The atmospheric CO2 column measurements using the 1572.33 nm CO2 lines. Two flights were made above the US Department of Energy's (DOE) SGP ARM site at altitudes from 3-8 km. These flights were coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft under the path. The increasing CO2 line absorptions with altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. In spring 2009 we improved the aircraft's nadir window and during July and August we made 9 additional 2 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 a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and eastern Virginia. Strong laser signals and clear Co2 line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. Analysis shows that the average signal levels follow predicted values, the altimetry measurements had an uncertainty of about 4 m, and that the average optical line depths follow the number density calculated from in-situ sensor readings. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. More details of the flights, measurements, analysis and scaling to space will be described in the presentation.

Abshire, James; Riris, Haris; Allan, Graham; Weaver, Clark; Mao, Jianping; Sun, Xiaoli; Hasselbrack, William

2010-05-01

77

Separation of 99m Tc from parent 99 Mo by solid-phase column extraction as a simple option for a new 99m Tc generator concept  

Microsoft Academic Search

Evidence is obtained to show that the liquidliquid extraction separation of99mTc from99Mo with methyl ethyl ketone, methyl propyl ketone and methyl isobutyl ketone can be transformed into a solid-phase column extraction procedure. The aqueous alkaline99molybdate solution is immobilized on a column of a granular large-pore diatomaceous earch support, which is the neluted with the abovementioned extractants. Rapid and clean separation

T. Braun; H. Imura; N. Suzuki

1987-01-01

78

Simulation and analysis of extractive distillation process in a valve tray column using the rate based model  

Microsoft Academic Search

Valve trays are becoming popular in the chemical process industries owing to their flexibility to handle a wide range of vapor\\u000a throughputs. Using the rigorous rate based model, the importance of the non-equilibrium approach is demonstrated for a typical\\u000a extractive distillation process in a Glitsch V-1 valve tray column. Simulation results based on an in-house developed code\\u000a indicated that the

Sasmita Pradhan; Aravamudan Kannan

2005-01-01

79

Determination of nitrated polynuclear aromatic hydrocarbons in particulate extracts by capillary column gas chromatography with nitrogen selective detection  

Microsoft Academic Search

The highly complex matrix of a diesel particulate extract was analyzed for nitrated polynuclear aromatic hydrocarbons (nitro-PAH) by use of fused-silica capillary column GC\\/thermionic nitrogen-phosphorus (GC\\/NPD) analysis of HPLC fractions. These samples were found to contain at least 100 nitro-PAH. Positive isomer identification for 17 nitro-PAH has been made utilizing the GC retention times of authentic standards and low- and

M. C. Paputa-Peck; R. S. Marano; Dennis. Schuetzle; T. L. Riley; C. V. Hampton; T. J. Prater; L. M. Skewes; T. E. Jensen; P. H. Ruehle; L. C. Bosch

1983-01-01

80

Pulsed ion extraction diagnostics in a quadrupole ion trap linear time-of-flight mass spectrometer  

Microsoft Academic Search

Pulsed extraction techniques are investigated for a quadrupole ion trap (QIT) interfaced to a linear time-of-flight (TOF) mass analyzer. A nonfocusing short-pulse mode of operation is developed and characterized. The short-pulse mode creates a near-monoenergetic ion packet, which is useful for reaction kinetics experiments and for making diagnostic measurements of the ion cloud size in the trap. Monopolar and bipolar

Beni B. Dangi; Nicholas A. Sassin; Kent M. Ervin

2010-01-01

81

Development of immunoaffinity columns for pyraclostrobin extraction from fruit juices and analysis by liquid chromatography with UV detection.  

PubMed

Pyraclostrobin belongs to a new generation of fungicides widely used to preserve high valuable crops. In the present study, three monoclonal antibodies with different affinities to this modern strobilurin have been evaluated for their usefulness in the production of immunoaffinity columns suitable for the solid-phase extraction, concentration, and clean-up of residues from food commodities. Different immunosorbents were produced and characterized in terms of antibody immobilization efficiency, immunosorbent binding capacity, optimum elution conditions, and reusability. Covalent coupling of the antibodies to Sepharose-CNBr gel took place with high yield (over 90%), whereas the immunosorbent efficacy to retain the analyte (from 28 to 68%) was shown to depend on the amount and type of antibody immobilized on the support. As a matter of fact, columns prepared with the monoclonal antibody PYs5#14 were able to selectively bound up to 53 ?g of pyraclostrobin per gram of beads. Acetonitrile solutions were preferred over methanolic ones for analyte elution, and some immunosorbents could be reused at least 4-6 times provided that the amount of pyraclostrobin and the volume of sample did not overload the column. Effectiveness of the selected immunoaffinity column was evidenced by the development of an extraction procedure for pyraclostrobin residues from fruit juices and further determination by high-performance liquid chromatography with UV detection. A concentration factor of 50 times was achieved with the developed immunoaffinity column, which eventually resulted in a limit of quantification of 0.01 mg L(-1). Finally, quantitative recoveries were obtained on apple juice and red grape must samples spiked with pyraclostrobin from 0.01 to 1 mg L(-1). PMID:21477805

Esteve-Turrillas, Francesc A; Mercader, Josep V; Agulló, Consuelo; Abad-Somovilla, Antonio; Abad-Fuentes, Antonio

2011-03-21

82

Simultaneous micro steam distillation\\/solvent extraction for the isolation of semivolatile flavor compounds from cinnamon and their separation by series coupled-column gas chromatography  

Microsoft Academic Search

Simultaneous micro steam distillation\\/solvent extraction is an efficient method of extracting semivolatile flavor and fragrance compounds from cinnamon for subsequent separation by series coupled-column gas chromatography. With pentane as the extraction solvent and an extraction time of 1.5 h clean extracts requiring no further sample preparation prior to gas Chromatographic analysis are obtained. It is shown that adulteration of cinnamon

Arya Jayatilaka; Salwa K. Poole; Colin F. Poole; Tina M. P. Chichila

1995-01-01

83

Quantitative multi-residue determination of ?-agonists in bovine urine using on-line immunoaffinity extraction-coupled column packed capillary liquid chromatography-tandem mass spectrometry  

Microsoft Academic Search

This report demonstrates the potential of on-line immunoaffinity extraction and coupled column packed capillary liquid chromatography-ion spray tandem mass spectrometry for multi-residue determination of five ?-agonists, clenbuterol, mabuterol, mapenterol, methylclenbuterol, and tolubuterol, in bovine urine using an automated column switching system. Trace enrichment and preliminary sample cleanup was performed on-line using bovine urine diluted with phosphate-buffered saline. The column switching

Jenny Cai; Jack Henion

1997-01-01

84

Pulsed Airborne Lidar measurements of Atmospheric CO2 Column Absorption and Line Shapes from 3-13 km altitudes  

NASA Astrophysics Data System (ADS)

We have developed a lidar technique for measuring the tropospheric CO2 concentrations as a candidate for NASA’s planned ASCENDS mission. Our technique uses two pulsed laser transmitters allowing simultaneous measurement of a CO2 absorption line in the 1570 nm band, O2 extinction in the Oxygen A-band and surface height and backscatter. The lidar measures the energy and time of flight of the laser echoes reflected from the atmosphere and surface. The lasers are stepped in wavelength across the CO2 line and an O2 line region during the measurement. The receiver uses a telescope and photon counting detectors, and measures the background light and energies of the laser echoes from the surface along with scattering from any aerosols in the path. The gas extinction and column densities for the CO2 and O2 gases are estimated from the ratio of the on- and off- line signals via the DIAL technique. Time gating is used to isolate the laser echo signals from the surface, and to reject laser photons scattered in the atmosphere. We have developed an airborne lidar to demonstrate the CO2 measurement from the NASA Glenn Lear-25 aircraft. The airborne lidar steps the pulsed laser’s wavelength across a selected CO2 line with 20 steps per scan. The line scan rate is 450 Hz, laser pulse energy is 25 uJ and laser pulse widths are 1 usec. The time resolved laser backscatter is collected by a 20 cm telescope, detected by a photomultiplier and is recorded by a photon counting system. We made initial airborne measurements on flights during October and December 2008. Laser backscatter and absorption measurements were made over a variety of land and water surfaces and through thin and broken clouds. Atmospheric CO2 column measurements using the 1571.4, 1572.02 and 1572.33 nm CO2 lines. Two flights were made above the DOE SGP ARM site at altitudes from 3-8 km. These flights were coordinated with DOE investigators who flew an in-situ CO2 sensor on a Cessna aircraft under the path. The increasing CO2 line absorptions with altitudes were evident and comparison with in-situ measurements showed agreements to 6 ppm. This spring we improved the aircraft’s nadir window. During July and August 2009 we made 9 additional 2 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 a variety of surface types in Nebraska, Illinois, the SGP ARM site, and near and over the Chesapeake Bay in North Carolina and Virginia. Strong laser signals and clear line shapes were observed at all altitudes, and some measurements were made through thin clouds. The flights over the ARM site were underflown with in-situ measurements made from the DOE Cessna. The Oklahoma and east coast flights were coordinated with a LaRC/ITT CO2 lidar on the LaRC UC-12 aircraft, a LaRC in-situ CO2 sensor, and the Oklahoma flights also included a JPL CO2 lidar on a Twin Otter aircraft. Ed Browell and Gary Spiers led the LaRC and JPL teams. More details of the flights, measurements and their analysis will be described in the presentation.

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

2009-12-01

85

H- extraction from electron-cyclotron-resonance-driven multicusp volume source operated in pulsed mode  

NASA Astrophysics Data System (ADS)

H2 microwave (2.45 GHz) pulsed plasma is produced from seven elementary electron cyclotron resonance sources installed into the magnetic multipole chamber ``Camembert III'' (École Polytechnique-Palaiseau) from which H- extraction takes place. The negative-ion and electron extracted currents are studied through electrical measurements and the plasma parameters by means of electrostatic probe under various experimental conditions. The role of the plasma electrode bias and the discharge duty cycle in the extraction process is emphasized. The gas breakdown at the beginning of every pulse gives rise to variations of the plasma characteristic parameters in comparison with those established at the later time of the pulse, where the electron temperature, the plasma potential, and the floating potential converge to the values obtained for a continuous plasma. The electron density is significantly enhanced in the pulsed mode.

Svarnas, P.; Bacal, M.; Auvray, P.; Béchu, S.; Pelletier, J.

2006-03-01

86

Dynamic fractionation of trace metals in soil and sediment samples using rotating coiled column extraction and sequential injection microcolumn extraction: a comparative study.  

PubMed

Dynamic fractionation has been recognized as an appealing alternative to conventional equilibrium-based sequential extraction procedures (SEPs) for partitioning of trace elements (TE) in environmental solid samples. This paper reports the first attempt for harmonization of flow-through dynamic fractionation using two novel methods, the so-called sequential injection microcolumn (SIMC) extraction and rotating coiled column (RCC) extraction. In SIMC extraction, a column packed with the solid sample is clustered in a sequential injection system, while in RCC, the particulate matter is retained under the action of centrifugal forces. In both methods, the leachants are continuously pumped through the solid substrates by the use of either peristaltic or syringe pumps. A five-step SEP was selected for partitioning of Cu, Pb and Zn in water soluble/exchangeable, acid-soluble, easily reducible, easily oxidizable and moderately reducible fractions from 0.2 to 0.5 g samples at an extractant flow rate of 1.0 mL min(-1) prior to leachate analysis by inductively coupled plasma-atomic emission spectrometry. Similarities and discrepancies between both dynamic approaches were ascertained by fractionation of TE in certified reference materials, namely, SRM 2711 Montana Soil and GBW 07311 sediment, and two real soil samples as well. Notwithstanding the different extraction conditions set by both methods, similar trends of metal distribution were in generally found. The most critical parameters for reliable assessment of mobilizable pools of TE in worse-case scenarios are the size-distribution of sample particles, the density of particles, the content of organic matter and the concentration of major elements. For reference materials and a soil rich in organic matter, the extraction in RCC results in slightly higher recoveries of environmentally relevant fractions of TE, whereas SIMC leaching is more effective for calcareous soils. PMID:19615513

Rosende, Maria; Savonina, Elena Yu; Fedotov, Petr S; Miró, Manuel; Cerdà, Víctor; Wennrich, Rainer

2008-11-14

87

Metal extractability from contaminated SRS sediments: Comparison of column and batch results  

Microsoft Academic Search

Tims Branch, a stream on the U.S. Department of Energy's Sa- vannah River Site located near Aiken, South Carolina, received sig- nificant amounts U and Ni as a result of nuclear materials produc- tion and refinement. Batch and column experiments were used to evaluate potential remediation scenarios and the migration hazard of U and Ni from flood-plain sediments collected along

J. C. Seaman; V. M. Vulava; A. G. Sowder; B. P. Jackson; S. A. Aburime; P. M. Bertsch

2005-01-01

88

Continuous-flow fractionation of selenium in contaminated sediment and soil samples using rotating coiled column and microcolumn extraction.  

PubMed

Dynamic fractionation is considered to be an attractive alternative to conventional batch sequential extraction procedures for partitioning of trace metals and metalloids in environmental solid samples. This paper reports the first results on the continuous-flow dynamic fractionation of selenium using two different extraction systems, a microcolumn (MC) packed with the solid sample and a rotating coiled column (RCC) in which the particulate matter is retained under the action of centrifugal forces. The eluents (leachants) were applied in correspondence with a four-step sequential extraction scheme for selenium addressing "soluble", "adsorbed", "organically bound", and "elemental" Se fractions extractable by distilled water, phosphate buffer, tetramethylammonium hydroxide, and sodium sulphite solutions, respectively. Selenium was determined in the effluent by using an inductively coupled plasma atomic emission spectrometer. Contaminated creek sediment and dumped waste (soil) samples from the abandoned mining area were used to evaluate resemblances and discrepancies of two continuous-flow methods for Se fractionation. In general, similar trends were found for Se distribution between extractable and residual fractions. However, for the dumped waste sample which is rich in organic matter, the extraction in RCC provided more effective recovery of environmentally relevant Se forms (the first three leachable fractions). The most evident deviation was observed for "adsorbed" Se (recoveries by RCC and MC are 43 and 7 mg kg(-1), respectively). The data obtained were correlated with peculiarities of samples under investigation and operational principles of RCC and MC. PMID:22265512

Savonina, Elena Yu; Fedotov, Petr S; Wennrich, Rainer

2011-11-09

89

Use of cyanopropyl-bonded hplc column for bioassay-directed fractionation of organic extracts from incinerator emissions  

SciTech Connect

The present study has shown that cyanopropyl-(CN) bonded silica HPLC columns are applicable for the fractionation of mass and mutagenic activity of organic extracts from some incinerator emissions. Dichloromethane-extractable organics from particles emitted by two different municipal waste incinerators and by a pilot-scale rotary kiln incinerator that was combusting polyethylene were fractionated by HPLC, and the mutagenicity of the fractions was determined by means of a microsuspension mutagenicity assay with Salmonella TA98. The CN-bonded silica columns provided high (80-100 percent) mass and mutagenicity recoveries for most emission extracts, and it fractionated the mutagenic activity. The results suggest that the emissions from municipal waste incinerators contain a high amount of direct-acting (-S9) mutagenic activity that is resolvable by HPLC using CN-bonded silica. Sub-fractionation of selected mutagenic HPLC fractions and subsequent analysis by gas chromatography/mass spectroscopy can be used to identify mutagenic species within complex incinerator emissions. The coupling of microsuspension bioassays to HPLC fractionation should be a useful tool for this type of analysis.

DeMarini, D.M.; Williams, R.W.; Brooks, L.R.; Taylor, M.S.

1992-01-01

90

Multilevel model analysis of energy extraction from a KrF laser medium by short pulses  

SciTech Connect

Amplification of short pulse KrF lasers is theoretically studied by using both coherent and incoherent interaction models, which consist of five vibrational levels in the upper laser state and a single repulsive lower laser state. The multilevel models predict a significant decrease in the saturation energies for short applied laser pulses. When the laser pulse width is extremely short ({le}1 ps), the higher vibrational levels in the upper KrF laser state are repumped from the lower laser state instead of being extracted by the laser pulse. Since the small-signal gain also decreases as the applied pulse width decreases, due to mismatch between the laser pulse and the KrF gain spectrum, the energy extraction efficiencies for subpicosecond laser pulses deteriorate significantly. For longer pulse widths ({ge}10 ps), population repumping from the KrF(C) state increases the effective saturation energy of the KrF(B) state. A steady-state population of {approx}28% relative to the B-state population is estimated for the C state from recent experimental results of KrF gain recovery.

Kannari, F. (Department of Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223, Japan (JP))

1990-05-01

91

Extraction and separation of metal ions by a column packed with polystyrene microcapsules containing Aliquat 336  

Microsoft Academic Search

Since the 1990s, the use of microcapsules as a supporting material for a metal extractant has developed quickly. Although there are many microcapsule preparation methods that exist now, most are time- and energy-consuming. Economical and simple methods for the preparation of uniform extractant microcapsules are necessary for the development of microcapsule-extraction processes. In this paper, the preparation of polystyrene microcapsules

W. W. Yang; G. S. Luo; X. C. Gong

2005-01-01

92

A feature extraction method for the signal sorting of interleaved radar pulse serial  

Microsoft Academic Search

In this paper, a new feature extraction method for radar pulse sequences is presented based on structure function and empirical\\u000a mode decomposition. In this method, 2-D feature information was constituted by using radio frequency and time-of-arrival,\\u000a which analyzed the feature of radar pulse sequences for the very first time by employing structure function and empirical\\u000a mode decomposition. The experiment shows

Qiang Guo; Xingzhou Zhang; Zheng Li

2007-01-01

93

Technique for the removal of electrons from an extracted, pulsed, H{sup {minus}} ion beam  

SciTech Connect

A small, permanent-magnet insert structure for the removal of electrons from pulsed, extracted, negative ion beams has been developed at Lawrence Berkeley National Laboratory. The device was computer modeled and designed for an extraction field strength of 3 kV/mm. The testing was carried out with a rf driven multicusp ion source optimized for the production of H{sup {minus}} ions and pulsed at a few Hz with pulse widths of several hundreds of {mu}s. It is demonstrated that the insert structure together with a collar can remove over 98{percent} of electrons from the extracted H{sup {minus}} ion beam without any significant deterioration of the H{sup {minus}} ion output. Application to other negative ion beams can be expected from this magnetic collar insert. {copyright} {ital 1996 American Institute of Physics.}

Perkins, L.T.; Herz, P.R.; Leung, K.N.; Pickard, D.S. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

1996-10-01

94

Biodegradation of chlorobenzene using immobilized crude extracts in packed bed column  

Microsoft Academic Search

Pseudomonas aeruginosa has been identified as potential organism to decompose chlorobenzene by its crude extract through immobilization technique. P. aeruginosa was grown on chlorobenzene as sole source of carbon and energy. Chlorobenzene was used as an inducer to develop specific intracellular enzymes which will decompose chlorobenzene to non toxic substance. Crude cell extracts produced which contains intracellular enzyme, were immobilized

R. Manikandan; H. J. Prabhu; P. Sivashanmugam

95

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

Microsoft Academic Search

A new micellar electrokinetic chromatography (MEKC) method using beta-cyclodextrins (?-CDs) and 1-butyl-3-methylimidazolium\\u000a 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\\u000a flow injection (FI) technique using a micro-column packed with coal cinders (the by-products from

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

2011-01-01

96

Extraction of Intercellular Components by Pulsed Electric Fields  

Microsoft Academic Search

\\u000a During the last decades there was observed a growing interest in electric field application for treatment of food and agricultural\\u000a raw materials. In early studies of Russian researchers the electrical treatment was applied for intensification of the process\\u000a of juice extraction from fruits and vegetables (Flaumenbaum, 1949), for sugar diffusion from beet (Zagorulko, 1958), and as a promising method of

E. Vorobiev; N. I. Lebovka

97

[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

98

One-step column chromatographic extraction with gradient elution followed by automatic separation of volatiles, flavonoids and polysaccharides from Citrus grandis.  

PubMed

Citrus grandis Tomentosa is widely used in traditional Chinese medicine and health foods. Its functional components include volatiles, flavonoids and polysaccharides which cannot be effectively extracted through traditional methods. A column chromatographic extraction with gradient elution was developed for one-step extraction of all bioactive substances from C. grandis. Dried material was loaded into a column with petroleum ether: ethanol (8:2, PE) and sequentially eluted with 2-fold PE, 3-fold ethanol: water (6:4) and 8-fold water. The elutes was separated into an ether fraction containing volatiles and an ethanol-water fraction containing flavonoids and polysaccharides. The later was separated into flavonoids and polysaccharides by 80% ethanol precipitation of polysaccharides. Through this procedure, volatiles, flavonoids and polysaccharides in C. grandis were simultaneously extracted at 98% extraction rates and simply separated at higher than 95% recovery rates. The method provides a simple and high-efficient extraction and separation of wide range bioactive substances. PMID:24128512

Han, Han-Bing; Li, Hui; Hao, Rui-Lin; Chen, Ya-Fei; Ni, He; Li, Hai-Hang

2013-09-03

99

Solid-phase extraction of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid from urine drug-testing specimens with the cerex polycrom-THC column.  

PubMed

Confirmation of drugs of abuse by gas chromatography-mass spectrometry (GC-MS) is the most time-consuming process used by drug-testing laboratories. Cost effectiveness and competitive turnaround times for testing results demand fast, efficient, and reliable extraction methods. We applied the Cerex Polycrom-THC solid-phase extraction (SPE) column to the extraction of 11-nor-delta9-tetrahydrocannabinol carboxylic acid (9-THCA) from urine. This column uses an anion exchange divinyl-benzene copolymer, which requires no pH adjustment after hydrolysis of the THC-glucuronide with base, as is necessary with many other SPE columns. With urine, no preconditioning of the SPE column was necessary. After extraction, trimethylsilation derivatization was performed with N-methyl-N-(trimethylsilyl) trifluoroacetamide. This further improved efficiency because no heated incubation was required. A method correlation to an existing liquid-liquid extraction was performed. Analysis was on a Finnigan Voyager GC-MS with a 2.5-min run time per injection. Using 9-THCA-d9 deuterated internal standard, the assay was linear from 2 to 2000 ng/mL. Total precision at the 15-ng/mL cutoff concentration was 4.4%. The Cerex column was also evaluated for interference using two common drug-test adulterants, Klear and Urine Luck. Considerably less interference was observed when compared to an existing liquid-liquid method. PMID:10872570

Crockett, D K; Nelson, G; Dimson, P; Urry, F M

100

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

NASA Astrophysics Data System (ADS)

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.; Thakur, S. C.; Brandt, C.; Sechrest, Y.; Tynan, G. R.; Munsat, T.

2013-08-01

101

Enhanced bioethanol dehydration by extractive and azeotropic distillation in dividing-wall columns  

Microsoft Academic Search

The industrial production of anhydrous bioethanol requires energy demanding distillation steps to overcome the azeotropic behavior of ethanol–water mixture. In spite of the recent developments in pervaporation and adsorption with molecular sieves, the large scale production is dominated by extractive and azeotropic distillation as the separation of choice.This study proposes novel distillation technologies for enhanced bioethanol dehydration, by extending the

Anton A. Kiss; David J-. P. C. Suszwalak

102

Determination of ricin by nano liquid chromatography/mass spectrometry after extraction using lactose-immobilized monolithic silica spin column.  

PubMed

Ricin is a glycosylated proteinous toxin that is registered as toxic substance by Chemical Weapons convention. Current detection methods can result in false negatives and/or positives, and their criteria are not based on the identification of the protein amino acid sequences. In this study, lactose-immobilized monolithic silica extraction followed by tryptic digestion and liquid chromatography/mass spectrometry (LC/MS) was developed as a method for rapid and accurate determination of ricin. Lactose, which was immobilized on monolithic silica, was used as a capture ligand for ricin extraction from the sample solution, and the silica was supported in a disk-packed spin column. Recovery of ricin was more than 40%. After extraction, the extract was digested with trypsin and analyzed by LC/MS. The accurate masses of molecular ions and MS/MS spectra of the separated peptide peaks were measured by Fourier transform-MS and linear iontrap-MS, respectively. Six peptides, which were derived from the ricin A-(m/z 537.8, 448.8 and 586.8) and B-chains (m/z 701.3, 647.8 and 616.8), were chosen as marker peptides for the identification of ricin. Among these marker peptides, two peptides were ricin-specific. This method was applied to the determination of ricin from crude samples. The monolithic silica extraction removed most contaminant peaks from the total ion chromatogram of the sample, and the six marker peptides were clearly detected by LC/MS. It takes about 5 h for detection and identification of more than 8 ng/ml of ricin through the whole handling, and this procedure will be able to deal with the terrorism using chemical weapon. PMID:21834021

Kanamori-Kataoka, Mieko; Kato, Haruhito; Uzawa, Hirotaka; Ohta, Shigenori; Takei, Yoshiyuki; Furuno, Masahiro; Seto, Yasuo

2011-08-01

103

High-Efficiency On-Line Solid-Phase Extraction Coupling to 15-150 um I.D. Column Liquid Chromatography for Proteomic Analysis  

SciTech Connect

Flexible manipulation of various properties of proteomic samples is important for proteomic analyses, but it has been little explored for newly developed approaches based on liquid chromatography (LC) in combination with mass spectrometry (MS). With miniaturization of the LC column inner diameter dimensions (required for improving the analysis sensitivity), this issue becomes more challenging due to the small flow rates and the increasing effects of extra column volume on the separation quality and its use for resolving complex proteomic mixtures. In this study, we used commercial switching valves (150-mm channels) to implement the on-line coupling of capillary LC columns with relatively large solid phase extraction (SPE) columns operated at 10,000 psi. With optimized column connections, switching modes, and SPE column dimensions, high-efficiency on-line SPE-capillary and nanoscale LC separations were obtained with peak capacities of~1000 for capillaries having inner diameters between 15 to 150 mm. The on-line coupled SPE columns increased the sample processing capabilities by~400-fold for sample solution volume and~10-fold for sample mass. The proteomic applications of this on-line SPE-capillary LC system were evaluated for analysis of both soluble and membrane protein tryptic digests. Used with an ion trap tandem MS we could typically identify 1100-1500 peptides for analyses in a single 5-hour run. Peptides extracted on the SPE column and eluted from the LC column covered a hydrophilicity/hydrophobicity range that include an estimated~98% of all the tryptic peptides. The present implementation also facilitates automation and enables use of both disposable SPE columns and electrospray emitters, providing a robust basis for routine proteomic analyses.

Shen, Yufeng (BATTELLE (PACIFIC NW LAB)); Moore, Ronald J. (BATTELLE (PACIFIC NW LAB)); Zhao, Rui (BATTELLE (PACIFIC NW LAB)); Blonder, Josip (BATTELLE (PACIFIC NW LAB)); Auberry, Deanna L. (BATTELLE (PACIFIC NW LAB)); Masselon, Christophe D. (BATTELLE (PACIFIC NW LAB)); Pasa Tolic, Ljiljana (BATTELLE (PACIFIC NW LAB)); Hixson, Kim K. (BATTELLE (PACIFIC NW LAB)); Auberry, Kenneth J. (BATTELLE (PACIFIC NW LAB)); Smith, Richard D. (BATTELLE (PACIFIC NW LAB))

2003-07-15

104

Determination of palladium in gasoline by neutron activation analysis and automated column extraction  

Microsoft Academic Search

Palladium in gasoline was determined by means of neutron activation analysis (NAA) and selective sorbent extraction. Unleaded\\u000a gasoline consistent with DIN EN 228, RON 95 was irradiated at a thermal neutron flux of ?th = 1.68 · 1013s–1cm–2 and an epithermal neutron flux of 3.32 · 1011s–1cm–2 for tirr = 12 h. The irradiated gasoline was digested with nitric acid

Michael Schwarzer; Michael Schuster; Roger von Hentig

2000-01-01

105

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

106

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

107

Extraction of zirconium and hafnium from nitric acid solutions by solid extractant based on tributyl phosphate  

SciTech Connect

A study has been made of extraction equilibrium and kinetics and the influence of temperature and aqueous phase acidity on the extraction of zirconium and hafnium from nitric acid solutions by a solid extractant based on tributyl phosphate. Results are presented from pilot-plant experiments on Zr and Hf extraction from acidic pulps with high silicon contents, using pulsed columns.

Korovin, V.Yu.; Yagodin, G.A.; Savel`eva, V.I. [Dnieper Scientific Center, Dneprodzerzhinsk (Ukraine)

1994-10-20

108

Comparative assessment of solid-phase extraction clean-up procedures, GC columns and perfluoroacylation reagents for determination of type B trichothecenes in wheat by GC–ECD  

Microsoft Academic Search

Various solid-phase extraction (SPE) procedures for clean-up, two perfluoroacylation reagents (pentafluoropropionic anhydride (PFPA) and heptafluorobutyric anhydride (HFBA)) and two chromatographic columns (HP-1701 and HP-5) have been assessed comparatively to achieve the determination of type B trichothecenes (deoxynivalenol (DON), nivalenol (NIV), 3- and 15-acetyldeoxynivalenol (3- and 15-ADON)) in wheat grain by gas chromatography (GC)–electron-capture detection (ECD). Spiked wheat samples were extracted

Francisco M. Valle-Algarra; Angel Medina; José V. Gimeno-Adelantado; Amparo Llorens; Misericordia Jiménez; Rufino Mateo

2005-01-01

109

Impact of apple processing modes on extracted juice quality: Pressing assisted by pulsed electric fields  

Microsoft Academic Search

The purpose of this study was to compare the effects of pulsed electric field (PEF) on apple juice characteristics (turbidity, polyphenolic content and antioxidant capacities). The pressing was used as a standard method for juice extraction. Experiments were carried out at a constant pressure (P=3bar) using a laboratory press cell. Two different methods for PEF application at 400V\\/cm were investigated

Nabil Grimi; Fatine Mamouni; Nikolaï Lebovka; Eugène Vorobiev; Jean Vaxelaire

2011-01-01

110

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

111

Extraction and analysis of flunitrazepam\\/7-aminoflunitrazepam in blood and urine by LC–PDA and GC–MS using butyl SPE columns  

Microsoft Academic Search

The forensic toxicology community has recognized flunitrazepam and its metabolite (7-aminoflunitrazepam) as compounds of concern for several years. In this procedure, the analytes were extracted from whole blood and urine onto single mode solid phase cartridges (butyl) using nitrazepam as an internal standard. The columns were washed with distilled water and hexane. All three compounds were eluted from the sorbent

Jeffery Hackett; Albert A. Elian

2006-01-01

112

Axiale Menging in een Extractiekolom Gepakt met Sulzer Statische Mengelementen II (Axial Mixing in an Extraction Column Packed with Sulzer Static Mixing Elements II).  

National Technical Information Service (NTIS)

In this study the axial mixing was investigated in a counter-flow (backflow) liquid-liquid extraction column packed with Sulzer static mixing elements. For this purpose a device was developed with which very specifically and selectively one of the two liq...

R. Weltevrede

1982-01-01

113

Effects of pulsed UV-light on peanut allergens in extracts and liquid peanut butter.  

PubMed

Pulsed ultraviolet (PUV) light, a nonthermal technology, was used to treat both the peanut extracts and liquid peanut butter. The objective was to determine if such treatment would lead to a reduction in the allergenic properties of the peanut extract and butter. Peanut samples were PUV treated using a Xenon RS-3000C under the following conditions: 3 pulses/s, 14.6 cm from the central axis of the lamp, 4 min (extract) or 3 min (liquid peanut butter). After the treatment, the peanut samples were centrifuged and the supernatants analyzed by SDS-PAGE and competitive inhibition enzyme-linked immunosorbent assay (ciELISA). For comparison, boiling treatments were also performed. SDS-PAGE showed that while boiling treatment had little effect on the peanut allergens, PUV-light-treated samples displayed a reduced solubility or level of peanut allergens (63 kDa). Solubility of another allergen (18 to 20 kDa) was unaffected. Insoluble aggregates formed were responsible for the reduced level of allergens in PUV-light-treated samples. ciELISA showed that untreated samples exhibited an IgE binding 7-fold higher than the PUV-treated samples. It was concluded that PUV light was effective in reducing IgE binding of peanut extracts and liquid peanut butter. The current study provides an approach to the development of a possibly less allergenic peanut product. However, the reduction in actual allergenicity needs to be confirmed by clinical studies. PMID:18576985

Chung, S-Y; Yang, W; Krishnamurthy, K

2008-06-01

114

Comparative assessment of solid-phase extraction clean-up procedures, GC columns and perfluoroacylation reagents for determination of type B trichothecenes in wheat by GC-ECD.  

PubMed

Various solid-phase extraction (SPE) procedures for clean-up, two perfluoroacylation reagents (pentafluoropropionic anhydride (PFPA) and heptafluorobutyric anhydride (HFBA)) and two chromatographic columns (HP-1701 and HP-5) have been assessed comparatively to achieve the determination of type B trichothecenes (deoxynivalenol (DON), nivalenol (NIV), 3- and 15-acetyldeoxynivalenol (3- and 15-ADON)) in wheat grain by gas chromatography (GC)-electron-capture detection (ECD). Spiked wheat samples were extracted with acetonitrile-water (84:16, v/v). Tested SPE procedures were MycoSep 225 column, Florisil and different cartridges prepared in the laboratory with mixtures of various sorbents like alumina, Celite 545, C18, silica and charcoal. We propose MycoSep 225 column, and cartridges made with alumina-charcoal-silica and alumina-charcoal-C18 silica mixtures as clean-up procedures on the basis of recovery values (89.6, 87.3 and 86.1% for deoxynivalenol, respectively, at 1.0mg/kg spiking level). The two last procedures are less expensive. Pentafluoropropionic anhydride was more stable against moisture and less expensive, while recoveries were similar to those obtained with heptafluorobutyric anhydride. HP-1701 column can separate 3- and 15-acetyldeoxynivalenol derivatives while HP-5 cannot, although this last column provided lower bleed and better sensitivity. PMID:18969981

Valle-Algarra, Francisco M; Medina, Angel; Gimeno-Adelantado, José V; Llorens, Amparo; Jiménez, Misericordia; Mateo, Rufino

2005-01-01

115

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

2005-12-20

116

Column internals  

SciTech Connect

In the fields of distillation, absorption, stripping and extraction, theory and technology go hand in hand. The thermodynamic principles of phase equilibrium and the concepts of mass transfer and fluid flow are of primary importance in all of these operations. The engineer must understand these phenomena to select equipment effectively. This article discusses the latest in commercial technology in column internals for gas-liquid and liquid-liquid contacting. The principles of operation are explained vis-a-vis the characteristics of the applications in which they are used. The focus is on moderate-to-large columns for refining and chemical applications. Guidelines for selecting the most appropriate type of device are presented, and examples of typical applications are described.

Bravo, J.L. [Shell Oil Co., Houston, TX (United States)

1998-02-01

117

Analysis of trace amounts of carbon dioxide, oxygen and carbon monoxide in nitrogen using dual capillary columns and a pulsed discharge helium ionisation detector.  

PubMed

Gas mixtures of trace amounts of carbon dioxide (CO(2)), dioxygen (O(2)), and carbon monoxide (CO) in dinitrogen (N(2)) were separated and quantified using parallel dual capillary columns and pulsed discharge helium ionisation detection (PDHID). The detection limits (9 x 10(-9) mol mol(-1) for CO(2), 7 x 10(-9) mol mol(-1) for O(2) and 37 x 10(-9) mol mol(-1) for CO) were lower than those reported previously for similar methods. Uncertainties were calculated and results were validated by comparison of the CO and CO(2) results with those obtained using conventional methods. The method was also used to analyse nitrogen, carbon dioxide and carbon monoxide in oxygen. PMID:17765907

Janse van Rensburg, M; Botha, A; Rohwer, E

2007-08-01

118

H{sup -} extraction from electron-cyclotron-resonance-driven multicusp volume source operated in pulsed mode  

SciTech Connect

H{sub 2} microwave (2.45 GHz) pulsed plasma is produced from seven elementary electron cyclotron resonance sources installed into the magnetic multipole chamber 'Camembert III' (Ecole Polytechnique-Palaiseau) from which H{sup -} extraction takes place. The negative-ion and electron extracted currents are studied through electrical measurements and the plasma parameters by means of electrostatic probe under various experimental conditions. The role of the plasma electrode bias and the discharge duty cycle in the extraction process is emphasized. The gas breakdown at the beginning of every pulse gives rise to variations of the plasma characteristic parameters in comparison with those established at the later time of the pulse, where the electron temperature, the plasma potential, and the floating potential converge to the values obtained for a continuous plasma. The electron density is significantly enhanced in the pulsed mode.

Svarnas, P.; Bacal, M.; Auvray, P.; Bechu, S.; Pelletier, J. [LPTP, Ecole Polytechnique, UMR 7648 du CNRS, 91128 Palaiseau (France); Centre de Recherche Plasmas-Materiaux-Nanostructures, LPSC, 53 rue des Martyrs, 38026 Grenoble Cedex (France)

2006-03-15

119

In vitro inhibition and dissolution of calcium oxalate by edible plant Trianthema monogyna and pulse Macrotyloma uniflorum extracts  

Microsoft Academic Search

Edible plant Trianthema monogyna (TME) and the pulse Macrotyloma uniflorum (KPE) extracts were found to be effective in the inhibition of calcium oxalate crystallization. Various physicochemical techniques, viz. conductometric and nephelometric titrations, UV–vis and IR spectroscopy and potential measurements in the absence and presence of these extracts were employed. TME and KPE both reduced the particle size considerably from 250

Ishwar Das; S. K. Gupta; Shoeb A. Ansari; V. N. Pandey; R. P. Rastogi

2005-01-01

120

In vitro inhibition and dissolution of calcium oxalate by edible plant Trianthema monogyna and pulse Macrotyloma uniflorum extracts  

Microsoft Academic Search

Edible plant Trianthema monogyna (TME) and the pulse Macrotyloma uniflorum (KPE) extracts were found to be effective in the inhibition of calcium oxalate crystallization. Various physicochemical techniques, viz. conductometric and nephelometric titrations, UV vis and IR spectroscopy and potential measurements in the absence and presence of these extracts were employed. TME and KPE both reduced the particle size considerably from

Ishwar Das; S. K. Gupta; Shoeb A. Ansari; V. N. Pandey; R. P. Rastogi

2005-01-01

121

Analysis of low levels of oxygen, carbon monoxide, and carbon dioxide in polyolefin feed streams using a pulsed discharge detector and two PLOT columns.  

PubMed

A gas chromatography (GC) method is developed for rapid analysis of polyolefin feed streams for the catalyst poisons CO, CO(2), and O(2). The method uses an HP MoleSieve column in parallel with a CP-PoraPLOT Q column and a pulsed discharge detector (PDD). Detection limits for each of the potential poisons are between 50 and 250 ppb. For a 10-ppm standard, the precision of the method was +/- 4.2% for oxygen, +/- 7.8% for carbon dioxide, and +/- 2.0% for carbon monoxide. In addition to the polyolefin feed stream, nitrogen and hydrogen feed streams are also analyzed. In each case, sampling is observed to be a critical issue, with air contamination of the sample cylinder often the limiting step in determining the true level of oxygen. It is also noted that large amounts of argon are present in the standards when nitrogen is used as a balance gas. Because the trace oxygen peak partly coelutes with the larger argon peak, it is suggested that helium be used as the balance gas for all standards. This general experimental arrangement should be effective when applied to feed streams for other polymers as well. PMID:14629793

Wurm, David B; Sun, Kefu; Winniford, William L

122

Automatic object extraction from VHR satellite SAR images using pulse coupled neural networks  

NASA Astrophysics Data System (ADS)

In this paper we investigate an unsupervised neural network approach for automatically extracting objects of interest from very high resolution (VHR) SAR images. The technique is based on the use of Pulse-Coupled Neural Networks (PCNN) which is a relatively novel technique based on models of the visual cortex of small mammals. The study discusses the use of PCNN technique in different applications. In a first case the extraction procedure is focused on the detection of buildings. In the second case the segmentation of a dark spot representing an oil spill in a SAR image is considered. The performance yielded by the PCNN is evaluated and critically discussed for a set of new generation of X-band SAR images taken by COSMO-Skymed and TerraSAR-X systems.

Del Frate, Fabio; Latini, Daniele; Pratola, Chiara

2010-10-01

123

Sensitive high-performance liquid chromatographic quantitation of gabapentin in human serum using liquid–liquid extraction and pre-column derivatization with 9-fluorenylmethyl chloroformate  

Microsoft Academic Search

Most of the published methods for analysis of gabapentin, an antiepileptic agent, in human serum are based on the same approach, involving o-phthaldialdehyde derivatization of deproteinized serum samples. The present paper however, describes a new, simple and sensitive high-performance liquid chromatographic method for determination of gabapentin in human serum using liquid–liquid extraction and 9-fluorenylmethyl chloroformate (FMOC-Cl) as pre-column labeling agent.

Gholamreza Bahrami; Amir Kiani

2006-01-01

124

Purification of (+)-dihydromyricetin from leaves extract of Ampelopsis grossedentata using high-speed countercurrent chromatograph with scale-up triple columns  

Microsoft Academic Search

Purification of (+)-dihydromyricetin from an extract (16 g) of leaves of Ampelopsis grossedentata was performed using a preparative triple-column countercurrent chromatograph. With a solvent system composed of n-hexane–ethyl acetate–methanol–water (1:3:2:4, v\\/v) 11.3 g of (+)-dihydromyricetin was obtained at a high purity of over 99% by HPLC at 254 nm in 9 h.

Qizhen Du; Weijian Cai; Ming Xia; Yoichiro Ito

2002-01-01

125

Purification of (+)-dihydromyricetin from leaves extract of Ampelopsis grossedentata using high-speed countercurrent chromatograph with scale-up triple columns.  

PubMed

Purification of (+)-dihydromyricetin from an extract (16 g) of leaves of Ampelopsis grossedentata was performed using a preparative triple-column countercurrent chromatograph. With a solvent system composed of n-hexane-ethyl acetate-methanol-water (1:3:2:4, v/v) 11.3 g of (+)-dihydromyricetin was obtained at a high purity of over 99% by HPLC at 254 nm in 9 h. PMID:12437181

Du, Qizhen; Cai, Weijian; Xia, Ming; Ito, Yoichiro

2002-10-11

126

Column solid phase extraction as preconcentration method for trace element determination in oxalic acid by atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry  

Microsoft Academic Search

Column solid phase extraction using solid sorbent [Foam-Pap - hexamethyleneammonium hexamethylenedithiocarbamate (HMDC) immobilized on polyurethane (PU) foam mixed with methyltrioctylammonium chloride (MTOAC) immobilized on filter paper as well as the solid sorbent PU-HMDC-MTOAC mixture of the above ligands immobilized on polyurethane foam only] was applied to the preconcentration of traces of Cd, Co, Cu, Hg, Ni and Pb in analytical-reagent

Anka Alexandrova; Sonja Arpadjan

1995-01-01

127

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

128

Novel Slow Extraction Scheme for Proton Accelerators Using Pulsed Dipole Correctors and Crystals  

SciTech Connect

Slow extraction of protons beams from circular accelerators is currently widely used for a variety of beam-based experiments. The method has some deficiencies including limited efficiency of extraction, radiation induced due to scattering on the electrostatic septa and limited beam pipe aperture, beam dynamics effects of space charge forces and magnet power supplies ripple. Here we present a novel slow extraction scheme employing a number of non-standard accelerator elements, such as Silicone crystal strips and pulsed stripline dipole correctors, and illustrate practicality of these examples at the 8 GeV proton Recycler Ring at Fermilab. The proposed method of non-resonant slow extraction of protons by bent crystals in combination with orbit fast deflectors shows great promise in simulations. We propose to initiate an R&D program in the Fermilab 8 GeV Recycler to address the key issues of the method: (a) feasibility of very short crystals - from few mm down to 0.2 mm; (b) their efficiency in the channelling and volume reflection regimes; (c) practical aspects of the fast deflectors.

Shiltsev, V.; /Fermilab

2012-05-01

129

Analysis of phase composition in aqueous two-phase systems using a two-column chromatographic method: Application to lactic acid production by extractive fermentation.  

PubMed

A new chromatographic system for the simultaneous analysis of polyethylene glycol, dextran, sugars, and low-molecular-weight fatty acids was developed. The system is based on a gel exclusion column which allows a first separation between high- and low-molecular-weight compounds, and a cationic exchange column used to further separate the low-molecular-weight compounds. Two applications of the system were demonstrated: (i) after optimizing eluent conditions the gel exclusion column was used to determine the influence of lactic acid, phosphate buffer, and lactic acid bacteria on the ethylene oxide propylene oxide-dextran T40 phase diagram by HPLC; (ii) the ion exchange column was coupled in series with the gel exclusion column and the concentration of polyethylene glycol, dextran, glucose, lactate, acetate, and formate was determined in samples from the fermentative production of lactic acid in a polyethylene glycol 8000-dextran T40 aqueous two-phase system. The fermentation was operated without pH control in a repeated extractive batch mode, where the cell-free top phase was replaced four times, whereas the cell-containing bottom phase was reused repeatedly. The yield was 1.1 mol of lactic acid formed per mole of glucose added and the productivity was 4.7 mM.h(-1). The polymeric composition of the fermentation system was monitored during the five repeated extractive batches, and it showed a progressive depletion in polyethylene glycol and a progressive enrichment in dextran. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 303-311, 1997. PMID:18634096

Planas, J; Lefebvre, D; Tjerneld, F; Hahn-Hägerdal, B

1997-05-20

130

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

131

Determination of benzodiazepines in human hair by on-line high-performance liquid chromatography using a restricted access extraction column.  

PubMed

A method is described for the identification of five frequently prescribed benzodiazepines (BZD) (clonazepam, diazepam, flunitrazepam, midazolam and oxazepam) in human hair samples by reversed phase HPLC, following on-line simple enrichment and clean-up on a restricted access extraction column. 50mg of powdered hair were incubated (2h at 45 degrees C) after sonication (1h) in 1 ml of the following solution (methanol:ammonia, 97.5/2.5, v/v). The aliquot was centrifuged and the methanolic phase transferred to a conical tube and evaporated under a gentle stream of nitrogen. The residue was reconstituted by adding 100 microl of a mixture of phosphate buffer (20mM, pH=2.2) and acetonitrile (94/6, v/v). A total of 80 microl were injected into the system with the column switching technique. The pre-column or clean-up column was washed with phosphate buffer pH=7.2. The drugs retained on the pre-column were then eluted in the back-flush mode and separated on a C(8) semi micro column, Lichrospher select B, 125 mm x 3 mm. The BZD were determined by a photodiode-array detector at 254 nm, using reference data (retention time and UV spectra) stored in a personal library. The method showed excellent linearity between 0.5 and 20 ng/mg of hair for clonazepam, flunitrazepam and midazolam and between 0.5 and 100 ng/mg of hair for diazepam and oxazepam. Finally, the present method has been applied to a number of forensic cases in our laboratory. PMID:11731192

El Mahjoub, A; Staub, C

2001-11-15

132

Extraction of Helium from Individual IDPs and Lunar Grains by Pulse Heating  

NASA Astrophysics Data System (ADS)

We have reported on the extraction of helium and neon from individual IDPs by step-heating (1,2). The purpose of the study was to see if differences in release patterns existed which might shed light on the heating experienced by the particles in their deceleration during descent in the Earth's upper atmosphere. Flynn (3), as well as earlier investigators, has shown that dust particles originating in high perihelia comets or in asteroids would, in general, have less energy and hence are heated less than low perihelia comets. In a study of 20 particles (2) it was found that 12 contained an appreciable amount of helium, and this was released in the same general temperature range as found for typical lunar grains. Four particles contained considerably less helium, and this was released at a higher temperature. The remaining particles contained essentially no helium. In a more recent study, fragments of 12 IDPs were investigated as a part of a coordinated investigation. Other fragments of the same IDPs are being examined for elemental and mineralogical content by other investigators. In the new work (4) the gas is extracted by a succession of 5-second constant-power pulses of increasing power, closely resembling the heat pulses experienced by IDPs in their deceleration in the atmosphere (5). The amount of gas removed is studied as a function of the peak temperature reached in the individual pulses. Flynn and Sutton (6) and Flynn et al. (7), using Transmission Electron Microscopy (TEM) and Synchrotron X-ray Fluorescence (SXRF) for trace element analyses, have reported low zinc abundances in some IDPs. They believe the low abundance could be due to the loss of volatile elements through heating during the deceleration of the particles during atmospheric entry. In our present study, low amounts of helium were found in fragments which were parts of the same IDPs as the fragments for which low Zn concentrations were found (G. Flynn, private communication). Whether the effect is due to the general loss of volatile elements during atmospheric entry, or has a more basic explanation relating to the origin or earlier history of the IDPs, remains an open question until more investigations are undertaken. In a related study, we undertook the extraction of helium and neon by pulse-heating of individual lunar surface grains to see if differences in the relative rates of extraction of the two gases could be observed. While only a limited number of grains have been investigated to date, some systematic differences appeared to emerge. For example, in the case of pyroxene and glassy grains, the relative proportions of total helium and neon released at a given temperature, as the temperature of the pulses increased, was approximately the same. On the other hand, for plagioclase and ilmenite, a distinctly higher temperature was required to remove the neon than was the case for helium. Hence, if the low volatile content of IDPs is due to atmospheric deceleration heating, the interpretation of differences or similarities observed for helium and other volatile elements must take into account the mineral composition of the particles. References: (1) Nier, A.O. and Schlutter, D. J. (1991) Meteoritics 26, 379. (2) Nier, A. O. and Schlutter, D. J. (1992) Meteoritics 27, (in press). (3) Flynn, G. J. (1989) Icarus 77, 287-310. (4) Nier. A. O. and Schlutter, D. J. (1992) Lunar Planet. Sci. (abstract) 23, 991-992. (5) Love, S. G. and Brownlee, D. E. (1991) Icarus 89, 26-43. (6) Flynn, G. J. and Sutton, S. R. (1992) Proc. Lunar Planet. Sci. 22nd, 171-184. (7) Flynn, G. J., Sutton, S. R., Thomas, K. L., Keller, L. P., and Klock, W. (1992) Lunar Planet. Sci. (abstract) 23rd, 375-376.

Nier, A. O.; Schlutter, D. J.

1992-07-01

133

Sensitive high-performance liquid chromatographic quantitation of gabapentin in human serum using liquid-liquid extraction and pre-column derivatization with 9-fluorenylmethyl chloroformate.  

PubMed

Most of the published methods for analysis of gabapentin, an antiepileptic agent, in human serum are based on the same approach, involving o-phthaldialdehyde derivatization of deproteinized serum samples. The present paper however, describes a new, simple and sensitive high-performance liquid chromatographic method for determination of gabapentin in human serum using liquid-liquid extraction and 9-fluorenylmethyl chloroformate (FMOC-Cl) as pre-column labeling agent. The drug and an internal standard (azithromycin) were extracted from serum by salting-out approach using a mixture of dichloromethane-2 propanol (1:1, v/v) as the extracting solvent. The extracted analytes were subjected to derivatization with FMOC-Cl in the presence of phosphate buffer (pH 7). A mobile phase consisting of methanol-0.05 M sodium phosphate buffer (73/27, v/v; pH of 3.9) containing 1 ml/l triethylamine was eluted and chromatographic separation was performed on a Shimpack CLC-C18 (150 mm x 4.6 mm) column. The standard curve was linear over the range of 0.03-20 microg/ml and limit of quantification was 0.03 microg/ml. The performance of analysis was studied and the validated method showed excellent performance in terms of selectivity, specificity, sensitivity, precision and accuracy. No interferences were found from commonly co-administered antiepileptic agents. PMID:16574508

Bahrami, Gholamreza; Kiani, Amir

2006-03-30

134

Pulsed electromembrane method for simultaneous extraction of drugs with different properties.  

PubMed

In the current work, a new setup including two cathodes and one anode was designed and employed for the first time for pulsed electromembrane extraction (PEME) of atenolol (ATE) and betaxolol (BET) from water, urine, and plasma samples. Because these analytes have different lipophilicities, the composition of supported liquid membrane (SLM) should be optimized for each drug and it is impossible to extract them simultaneously using common electromembrane setups. The SLMs employed for the extraction of BET and ATE were pure 2-nitrophenyl octyl ether (NPOE) and a mixture of 90% NPOE and 10% di-(2-ethylhexyl) phosphate (DEHP), respectively, which were immobilized in the pores of two different hollow fibers. An electric field of 100V was applied to transfer the analytes from the sample solution across the SLMs into acidic acceptor solutions with pH 1.0 that were located inside the lumens of hollow fibers. Preconcentration factors in the range of 69 to 363 and satisfactory repeatabilities (2.2 < relative standard deviation [RSD] < 7.4) were obtained in different matrices. The method offered a good linearity with correlations of determination (R2) higher than 0.9944 and was applied for determination and quantification of the analytes in some real samples. Finally, satisfactory results were obtained. PMID:23562379

Arjomandi-Behzad, Leila; Yamini, Yadollah; Rezazadeh, Maryam

2013-04-04

135

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

136

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

2013-09-10

137

Determination of Commonly Used Herbicides in Surface Water Using SolidPhase Extraction and Dual-Column HPLC-DAD  

Microsoft Academic Search

The present study describes the application of different solid-phase extraction techniques for the extraction, separation, and quantitative determination of 10 commonly used herbicides with different chemical structures (chlorsulfuron, diuron, bentazone, linuron, chlorpropham, fenoxoprop-ethyl, MCPA, diclofop-methyl, fluazifop-butyl, trifluraline) in water. Octadecyl (C18) Empore extraction disks, octadecyl (C18), and stryene divinylbenzene (SDB) Bond Elut Env cartridges were compared for solid-phase extraction efficiency.

GÜL ÖZHAN; SIBEL ÖZDEN; BUKET ALPERTUNGA

2005-01-01

138

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

139

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

PubMed

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 photothermal, photochemical, and photophysical effects. To date, there are no published data highlighting the effects of in vitro simulated gastric and intestinal digestion on the stability of PUV reduced allergen reactivity of food. In this study, PUV-treated shrimp extracts were subjected to simulated gastric fluid containing pepsin and simulated intestinal fluid containing trypsin and chymotrypsin, and then tested for changes in allergen potency. SDS-PAGE showed no major band deviation between undigested and digested PUV-treated shrimp extracts. IgE binding to tropomyosin remained markedly decreased as seen in Western blot analysis. Total shrimp allergen reactivity remained unchanged following in vitro peptic digestion and was markedly reduced following in vitro intestinal digestion as illustrated in indirect ELISA. The PUV reduced shrimp allergens remained at a low level under the in vitro simulated digestive conditions. The results inferred that PUV could be a potential method to create less allergenic shrimp products that would remain at a low allergen level under human gastric and intestinal digestive conditions. PMID:22278049

Yang, Wade W; Shriver, Sandra K; Chung, Si-Yin; Percival, Susan; Correll, Melanie J; Rababah, Taha M

2012-01-26

140

Solid phase extraction and spectrophotometric determination of mercury by adsorption of its diphenylthiocarbazone complex on an alumina column  

NASA Astrophysics Data System (ADS)

A simple method has been developed for the preconcentration of mercury based on the adsorption of its diphenylthiocarbazone complex on a neutral alumina column. The influence of acidity, eluting agents, stability of the column, sample volume and interfering ions has been investigated in detail. The adsorbed complex could be eluted using environmentally benign polyethylene glycol (PEG 400) and the concentration of mercury was determined by visible spectrophotometry at a wavelength maximum of 520 nm. A detection limit of 4 ?g L -1 could be achieved and the developed procedure was successfully applied for the determination of mercury in spiked water samples and city waste incineration ash (CRM176). The preconcentration factor attainable for quantitative recovery (>95%) of mercury(II) was 100 for a 1000 mL sample volume.

Rajesh, N.; Gurulakshmanan, G.

2008-02-01

141

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

NASA Astrophysics Data System (ADS)

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 use 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.

Jacobs, H. R.

1985-06-01

142

Acaricidal activity of petroleum ether extract of neem (Azadirachta indica) oil and its four fractions separated by column chromatography against Sarcoptes scabiei var. cuniculi larvae in vitro.  

PubMed

The petroleum ether extract of neem oil and its four fractions separated by column chromatography was diluted at different concentrations with liquid paraffin. The acaricidal bioassay was conducted using a dipping method. The results indicated that the median lethal concentration (LC50) of the petroleum ether extract (at the concentration of 500.0ml/l) was 70.9ml/l, 24h after treatment. At concentrations of 500.0, 250.0, 125.0, 62.5 and 31.2ml/l, the median lethal times (LT50) of the petroleum ether extract were 8.7, 8.8, 10.8, 11.5 and 13.1h, respectively. Thin-layer chromatography (TLC) showed that the petroleum ether extract of neem oil separated into four fractions (F1-F4). Acaricidal activity of 68.3% and 100.0% in the F2 and F4 was confirmed. These results suggest that petroleum ether extracts of neem oil and its four fractions possess useful acaricidal activity in vitro. PMID:22349080

Deng, Yunxia; Shi, Dongxia; Yin, Zhongqiong; Guo, Jianhong; Jia, Renyong; Xu, Jiao; Song, Xu; Lv, Cheng; Fan, Qiaojia; Liang, Xiaoxia; Shi, Fei; Ye, Gang; Zhang, Wei

2012-02-18

143

The perils of pathogen discovery: origin of a novel parvovirus-like hybrid genome traced to nucleic Acid extraction spin columns.  

PubMed

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; Chiu, Charles Y

2013-09-11

144

The effect of silanol masking on the recovery of picloram and other solutes from a hydrocarbonaceous pre-analysis extraction column  

SciTech Connect

The recoveries of picloram, picloram-methylester, hexazinone, benzene, and acetophenone from aqueous samples were studied using a commercially available hydrocarbonaceous pre-analysis extraction cartridge, both with and without tetrabutylammonium hydrogen sulfate (TBAHS) in the eluent. Extraction efficiency was found to be dependent on sample loading volume. The results suggest a mixed mechanism of retention involving both ''silanophilic'' and ''hydrophobic'' interactions in the absence of tetrabutylammonium ion. The ability of TBAHS to mask surface silanol groups and/or ion-pair with counterionic solutes is invoked to explain the observations. Chromatograms of the solutes obtained on a C/sub 18/ bonded analytical column in both the presence and absence of TBAHS are also presented.

Wells, J.M.

1982-12-01

145

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

146

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

147

Telescoping Columns.  

National Technical Information Service (NTIS)

A power operated telescoping column is described for the deployment and retraction of a large parabolic antenna for space applications. The column consists of several axially elongated rigid structural sections nested within one another. The outermost and...

J. T. Mazur

1978-01-01

148

"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

2012-04-19

149

Long Pulse H{sup -} Beam Extraction With A RF Driven Ion Source With Low Fraction Of Co-Extracted Electrons  

SciTech Connect

IPP Garching is developing H{sup -}/D{sup -} RF ion sources for the ITER neutral beam system. On the MANITU testbed the experiments are focussed on long pulse H{sup -}/D{sup -} beam extraction with a 100 kW prototype source. The negative ion production is based on surface conversion of atoms and positive ions on Caesium layers. In long pulses with H{sup -} beam extraction the ion currents were stable but with too high fraction of co-extracted electrons. The electron current could be lowered considerably by avoiding copper impurities from the Faraday screen in the plasma which was achieved by coating of the inner surfaces of the source with Molybdenum. A positive bias potential with respect to the source applied to the plasma grid, the bias plate or to a metal rod installed near the plasma grid enables regulation of the electron current during long pulses. In this way low values consistent with the ITER requirements can be achieved without significant loss of ion current.

Kraus, W.; Berger, M.; Fantz, U.; Franzen, P.; Froeschle, M.; Heinemann, B.; Riedl, R.; Speth, E.; Staebler, A.; Wuenderlich, D. [Max-Planck-Institut fuer Plasmaphysik, Boltzmannstr. 2, D-85748, Garching (Germany)

2009-03-12

150

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

151

Determination of fluazifop-butyl and fluazifop with the use of disposable solid phase extraction columns for selective clean-up and concentration of Soxhlet soil extracts  

Microsoft Academic Search

An analytical procedure based on the solid phase extraction technology has been developed for the clean-up and concentration of Soxhlet soil extracts containing fluazifop-butyl and fluazifop by the use of a phenyl phase cartridge. No liquid-liquid partition has been used; thus the consumption of organic solvents was limited and the use of chlorinated solvents could be avoided. Quantification has been

Marco Zanco; Gerd Pfister; Antonius Kettrup

1992-01-01

152

Pulse Coupled Neural Network for Automatic Features Extraction from COSMO-Skymed and TerraSAR-X Imagery  

Microsoft Academic Search

In this paper we test an unsupervised neural network approach for extracting features from very high resolution X-band SAR images. The purpose of this study is buildings recognition in images of low density urban areas, acquired by COSMO-Skymed and TerraSAR-X satellites, by means of Pulse Coupled Neural Network (PCNN), a relatively novel unsupervised algorithm based on models of the visual

Fabio Del Frate; Giorgio Licciardi; Fabio Pacifici; Chiara Pratola; Domenico Solimini

2009-01-01

153

CN.M.R. STUDIES OF A FLASH PYROLYSIS TAR AND A SUPERCRITICAL GAS EXTRACT USING MODERN PULSE SEQUENCES  

Microsoft Academic Search

The oil and the asphaltene obtained from a flash pyrolysis tar of an Australian sub-bituminous coal and the oil and asphaltene from a supercritical gas extract of an Australian bituminous coal were studied by ;c-n.m.r. apectroscopy using modern pulse sequences which distinguish between primary (CH3), secondary (CH2), tertiary )CH( and quaternary (C) carbons. The oil from the flash pyrolysis tar

John R. Kershaw; Richard I. Willing

1984-01-01

154

Determination of retigabine and its acetyl metabolite in biological matrices by on-line solid-phase extraction (column switching) liquid chromatography with tandem mass spectrometry.  

PubMed

A HPLC assay with tandem mass spectrometric detection in the positive-ion atmospheric pressure chemical ionisation (APCI) mode for the sensitive determination of retigabine [(I), D-23129] and its acetyl metabolite [(II), ADW 21-360] in plasma was developed, utilising the structural analogue (D-10328), (III), as internal standard. Automated on-line solid-phase extraction of diluted plasma samples, based on 200-microl plasma aliquots, at pH 6.5, allowed a reliable quantification of retigabine and the acetyl metabolite down to 1 ng/ml. Injection of 500 microl of diluted plasma onto a C2 stationary phase-based column switching system in combination with a 75 mm x 4 mm reversed-phase analytical column at a flow-rate of 0.5 ml/min provided cycle times of 4 min per sample. The standard curves were linear from 1 to 1000 ng/ml using weighted linear regression analysis (1/x2). The method is accurate (mean accuracy < or = +/- 10%), precise (RSD < +/- 15%) and sensitive, providing lower limits of quantification in plasma of 1 ng/ml for retigabine (I), and 2.5 ng/ml for the metabolite (II) with limits of detection of 0.5 ng/ml for both analytes. Up to 200 unknowns may be analysed each 24 h per analyst. PMID:11092590

Knebel, N G; Grieb, S; Leisenheimer, S; Locher, M

2000-10-01

155

A simple and rapid technique for recovery of (99m)Tc from low specific activity (n,gamma)(99)Mo based on solvent extraction and column chromatography.  

PubMed

A simple and inexpensive method of separation of (99m)Tc from (99)Mo produced by neutron activation of (98)Mo via the (98)Mo(n,gamma)(99)Mo nuclear reaction is described. The recovery of (99m)Tc was performed by solvent extraction technique followed by column (active alumina) chromatography. The overall radiochemical yield for the complete separation of (99m)Tc was 85-95% (n=10). The separated Na[(99m)Tc]TcO(4) was of high radionuclidic, radiochemical, and chemical purities. The method can be adopted for routine use of (99m)Tc in hospital radio-pharmacies utilizing low-medium specific activity (n,gamma)(99)Mo produced in a research reactor. PMID:19720541

Chattopadhyay, Sankha; Das, Sujata Saha; Barua, Luna

2009-08-14

156

Extraction and analysis of flunitrazepam/7-aminoflunitrazepam in blood and urine by LC-PDA and GC-MS using butyl SPE columns.  

PubMed

The forensic toxicology community has recognized flunitrazepam and its metabolite (7-aminoflunitrazepam) as compounds of concern for several years. In this procedure, the analytes were extracted from whole blood and urine onto single mode solid phase cartridges (butyl) using nitrazepam as an internal standard. The columns were washed with distilled water and hexane. All three compounds were eluted from the sorbent using an ethyl acetate-methanol solvent mixture. After collection and evaporation of the solvent, the residue was dissolved in A, 0.1% (v/v) aqueous trifluoroacetic acid for HPLC-PDA analysis or B, ethyl acetate for derivatization with pentafluoropropionic anhydride (PFPA) for analysis by gas chromatography-mass spectrometry (selected ion monitoring, SIM). A limit of quantitation for this method using HPLC-PDA was found to be 5 and 1.0 ng mL(-1) by SIM. PMID:15955650

Hackett, Jeffery; Elian, Albert A

2005-06-13

157

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

158

Multi-pulse extraction from Los Alamos Proton Storage Ring for radiographic applications  

SciTech Connect

In Proton Radiography, one of the goals is a motion picture of a rapidly moving object. The Los Alamos Proton Storage Ring (PSR) in its normal operating mode, delivers a single pulse approximately 120 ns wide (fwhm). In development runs at the PSR, the authors successfully demonstrated operation of a technique to deliver two pulses, each 40 nsec wide, with adjustable spacing.

Thiessen, H.A.; Neri, F.; Rust, K.; Redd, D.B.

1997-08-01

159

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

160

Long pulse beam extraction with a prototype ion source for the KSTAR neutral beam system  

SciTech Connect

Long pulse operational characteristics of the high current ion source for the KSTAR neutral beam system are described. The beam pulse length of 300 s was successfully operated at a beam power of 1.6 MW with a beam energy of 70 keV. Beam energy, beam current, beam divergence, arc power, and several other operational parameters were measured during a pulse to analyze the long pulse properties. The increase of the cooling water temperature of the accelerator grids and plasma generator components were measured by water flow calorimetric system using thermocouples. The temperature rises of the filament electrodes of the ion source and the G1 grids (plasma grids) of the accelerator turned out to be the critical factors of the long pulse operation in the current system.

Oh, Byung-Hoon; Chang, Doo-Hee; Jeong, Seung Ho; Lee, Kwang-Won; In, Sang-Ryul; Yoon, Byung-Joo; Seo, Min-Seok; Jin, Jung-Tae; Kim, Bum-Ryul; Chang, Dae-Sik; Jung, Ki-Sok; Kim, Jinchoon; Kim, Tae-Seong; Bae, Young Soon [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); ProScience, San Diego, California 92129 (United States); University of Science and Technology, Daejeon 305-353 (Korea, Republic of); National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of)

2008-02-15

161

Micro-scale membrane extraction of glyphosate and aminomethylphosphonic acid in water followed by high-performance liquid chromatography and post-column derivatization with fluorescence detector.  

PubMed

A carrier-mediated supported liquid membrane micro-extraction using single hollow fiber membrane suitable for the determination of the herbicide glyphosate and its main metabolite aminomethylphosphonic acid in water is reported. A solution of 0.20 M Aliquat-336, a cationic carrier, in di-n-hexyl ether was selected as the supported liquid. A 20 microL of 1.0 M potassium chloride as the acceptor phase was filled in the membrane lumen. The membrane was immersed in a 20 mL of pH 9.0 sample solution. After 60-min extraction, the acceptor phase was analyzed by high-performance liquid chromatography with post-column derivatization. The enrichment factors were found to be 853 and 136 for glyphosate and aminomethylphosphonic acid, respectively. The method detection limits are 0.22 microg/L for glyphosate and 3.40 microg/L for aminomethylphosphonic acid. The procedure was validated and showed good accuracy and precision over a large linear dynamic range. The validated method was tested for the analysis of both analytes in spiked groundwater with good success. PMID:18295220

Piriyapittaya, Montra; Jayanta, Siripastr; Mitra, Somenath; Leepipatpiboon, Natchanun

2008-02-02

162

Comparison of Alkaline Lysis with Electroextraction and Optimization of Electric Pulses to Extract Plasmid DNA from Escherichia coli.  

PubMed

The use of plasmid DNA (pDNA) as a pharmaceutical tool has increased since it represents a safer vector for gene transfer compared to viral vectors. Different pDNA extraction methods have been described; among them is alkaline lysis, currently the most commonly used. Although alkaline lysis represents an established method for isolation of pDNA, some drawbacks are recognized, such as entrapment of pDNA in cell debris, leading to lower pDNA recovery; the time-consuming process; and increase of the volume due to the buffers used, all leading to increased cost of production. We compared the concentration of extracted pDNA when two methods for extracting pDNA from Escherichia coli were used: alkaline lysis and a method based on membrane electroporation, electroextraction. At the same time, we also studied the effect of different pulse protocols on bacterial inactivation. The concentration of pDNA was assayed with anion exchange chromatography. When alkaline lysis was used, two incubations of lysis time (5 and 10 min) were compared in terms of the amount of isolated pDNA. We did not observe any difference in pDNA concentration regardless of incubation time used. In electroextraction, different pulse protocols were used in order to exceed the pDNA concentration obtained by alkaline lysis. We show that electroextraction gives a higher concentration of extracted pDNA than alkaline lysis, suggesting the use of electroporation as a potentially superior method for extracting pDNA from E. coli. In addition, electroextraction represents a quicker alternative to alkaline lysis for extracting pDNA. PMID:23831957

Haberl, Saša; Jarc, Marko; Strancar, Aleš; Peterka, Matjaž; Hodži?, Duša; Miklav?i?, Damijan

2013-07-06

163

Stereospecific determination of amisulpride, a new benzamide derivative, in human plasma and urine by automated solid-phase extraction and liquid chromatography on a chiral column application to pharmacokinetics  

Microsoft Academic Search

Amisulpride, a drug belonging to the benzamide series, demonstrates antischizophrenic and antidepressant (antidysthymic) properties in man. For the pharmacokinetic studies of the racemic drug in man, a method of determination based on solid-phase extraction (SPE) from plasma and HPLC on a stereoselective column was developed. For this aim, one millilitre of plasma, after the addition of the internal standard, tiapride

V. Ascalone; M. Ripamonti; B. Malavasi

1996-01-01

164

Trajan's Column  

NSDL National Science Digital Library

This Website, from McMaster University, uses the combined skills of artists, writers, programmers, and Web designers to create a resource for the study of Trajan's column, a Roman architectural monument. This 100-foot marble column, built during the reign of Emperor Trajan, 98-117 AD, is topped with a gilded statue of Trajan and decorated with carvings recounting Trajan's rule, primarily the Dacian Wars and his building projects. The heart of the Website is the database of 500 slides of the carvings; indexes allow users to view the slides in thematic groupings such as images of sides of the column, groups organized by subject keywords, or carvings made with specific tools. Cartoons or drawings of the column help to contextualize the details found in the slides, and essays provide more information on its design, construction, and preservation.

165

Differential pulse polarography determination of indium after column preconcentration with [1-(2-pyridylazo)-2-naphthol]-naphthalene adsorbent or its complex on microcrystalline naphthalene  

Microsoft Academic Search

A highly selective, sensitive and economical differential pulse polarographic method has been developed for the determination of trace amount of indium in various samples after adsorption of its 1-(2-pyridylazo)-2-naphthol on naphthalene in the pH range of 6.5–11.5. After filtration, the solid mass is shaken with 8 ml of 1 M hydrochloric acid and indium is determined by differential pulse polarography

Mohammad Ali Taher

2000-01-01

166

A High Power Pulse System for the Beam Extraction from CERN's Large Hadron Collider  

Microsoft Academic Search

CERN, the European Organization for Nuclear Research, is close to starting operation of the large hadron collider (LHC). A beam dumping system must protect the LHC machine from damage, by reliably and safely extracting and absorbing the circulating beams when requested. For this purpose a beam extraction system has been designed, built, installed and tested. It is composed of 15

E. Carlier; F. Castronuovo; L. Ducimetiere; E. B. Vossenberg

2008-01-01

167

Insecticidal and Repellent Properties of Subtropical Plant Extracts Against Pulse Beetle, Callosobruchus chinensis  

Microsoft Academic Search

Extracts of eight plants local to Oman, namely Qarat (Acacia nilotica), Mustafal (Annona squamosa), Shereesh (Azadirachta indica), Luban (Boswellia sacra), Kheshkhash (Crotolaria juncea), Zebrot (Jatropha dhofarica) Yas, (Myrtus communis) and Suwwad (Suaeda aegyptiaca) were prepared by steeping shaded dried leaf\\/seed powder of each plant in water and solvent (methanol or ethanol). The extracts were tested for their insecticidal and repellent

H. T. Al Lawati; K. M. Azam; M. L. Deadman

168

A Dual-Column Solid Phase Extraction Strategy for Online Collection and Preparation of Continuously Flowing Effluent Streams for Mass Spectrometry  

PubMed Central

Current desalination techniques for mass spectrometry-based protocols are problematic for performing temporal response studies where increased temporal resolution requires small samples and faster sampling frequencies, which greatly increases the number of samples and sample preparation time. These challenges are pertinent to cellular dynamics experiments, where it is important to sample the biological system frequently and with as little sample waste as possible. To address these needs, we present a dual-column online solid phase extraction (SPE) approach capable of preconcentrating and preparing a constantly perfusing sample stream, with minimal to no sample loss. This strategy is evaluated for use in microfluidic bioreactor studies specifically aimed at characterizing suitable sample flow rates, temporal resolving power, and analyte concentrations. In this work we demonstrate that this strategy may be used for flow rates as low as 500 nL/min, with temporal resolving power on the order of 3 minutes, with analyte loadings ranging from fmol to pmol for metabolites. Under these conditions recoveries of ca. 80% are obtained even at fmol loadings.

Enders, Jeffrey R.; Marasco, Christina C.; Wikswo, John P.

2012-01-01

169

A dual-column solid phase extraction strategy for online collection and preparation of continuously flowing effluent streams for mass spectrometry.  

PubMed

Current desalination techniques for mass spectrometry-based protocols are problematic for performing temporal response studies where increased temporal resolution requires small samples and faster sampling frequencies, which greatly increases the number of samples and sample preparation time. These challenges are pertinent to cellular dynamics experiments, where it is important to sample the biological system frequently and with as little sample waste as possible. To address these needs, we present a dual-column online solid phase extraction (SPE) approach capable of preconcentrating and preparing a constantly perfusing sample stream, with minimal to no sample loss. This strategy is evaluated for use in microfluidic bioreactor studies specifically aimed at characterizing suitable sample flow rates, temporal resolving power, and analyte concentrations. In this work, we demonstrate that this strategy may be used for flow rates as low as 500 nL/min, with temporal resolving power on the order of 3 min, with analyte loadings ranging from femtomoles to picomoles for metabolites. Under these conditions, recoveries of ca. 80% are obtained even at femtomole loadings. PMID:22967262

Enders, Jeffrey R; Marasco, Christina C; Wikswo, John P; McLean, John A

2012-09-25

170

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

171

Novel statistical technique of defective information extraction in pulsed eddy current NDE  

Microsoft Academic Search

The pulsed eddy current (PEC) technique as complementary approach of traditional eddy current method has found increasing applications in deep flaw detection and complex structure inspection. Considering the present PEC NDE (non- destructive evaluation) needs valid algorithms and techniques to implement signal processing in time domain, the novel statistical technique based on principle component analysis (PCA) and independent component analysis

Guang Yang; Qi Zhang; Yuning Yang; Gui Yun Tian

2011-01-01

172

Feature extraction using normalized cross-correlation for pulsed eddy current thermographic images  

Microsoft Academic Search

Pulsed eddy current (PEC) thermography is an emerging method in the field of non-destructive testing and evaluation (NDT&E). Defects can be characterized by tracking the diffusion of heat in a sample through the analysis of a sequence of PEC thermographic images. This study takes advantage of the capabilities of PEC thermography to gain quantitative information about complex geometrical defects, i.e.

A. R. Al-Qubaa; G. Y. Tian; J. Wilson; W. L. Woo; S. S. Dlay

2010-01-01

173

Sensitive mercury speciation by reversed-phase column high-performance liquid chromatography with UV-visible detection after solid-phase extraction using 6-mercaptopurine and dithizone.  

PubMed

A highly selective and sensitive method was developed for preconcentration of inorganic and organic mercury compounds followed by reversed-phase column high-performance liquid chromatography (RP-HPLC) with UV-visible detection. The method was based on the reaction of mercury with 6-mercaptopurine and solid-phase extraction (SPE) of the complex on an octadecylsilane (C18) cartridge. The complex was then treated with ammoniacal dithizone solution, and the complexes of inorganic and organic mercury with dithizone were eluted by methanol. The speciation analysis of methylmercury (MeHg), phenylmercury (PhHg), and inorganic Hg (II) was carried out by RP-HPLC. Some experimental variables that influence the SPE and derivatization, such as pH, chelating and derivatizing agent concentration, and surfactant addition, were investigated. The calibration graphs of MeHg, PhHg, and Hg (II) were linear [correlation coefficient (r) > 0.999] from the detection limits (0.12, 0.16, and 0.14 ng) to 8.5, 6.0, and 6.7 ng Hg, respectively. By applying the SPE procedure, a 100-fold concentration of the sample was obtained. The procedure was applied to sea water and tuna fish samples. The method's accuracy was investigated by using tuna fish certified reference material BCR 464 and by spiking the samples with different amounts of MeHg, PhHg, and Hg (II). The average recoveries of MeHg, PhHg, and Hg (II) from spiked samples (0.1-2.0 microg/L Hg) were 96 +/- 4, 98 +/- 3, and 104 +/- 4%, respectively. PMID:19202808

Hashemi-Moghaddam, Hamid; Saber-Tehrani, Mohamad

174

Estimation of cleanup time for continuous and pulsed soil vapor extraction  

Microsoft Academic Search

Soil vapor extraction (SVE) is a standard remediation technique for removing volatile organic compounds from contaminated soils. An important aspect in planning of SVE systems is the estimation of the time frame in which remediation can be achieved. In this study, analytical solutions are developed which can be used on the one hand for estimation of the required cleanup time

V. Kaleris; J. Croisé

1997-01-01

175

Simultaneous determination of palladium, platinum, rhodium and gold by on-line solid phase extraction and high performance liquid chromatography with 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine as pre-column derivatization regents  

Microsoft Academic Search

In this paper, 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine (HNATR) was synthesized. A new method for the simultaneous determination of palladium, platinum, rhodium and gold ions as metal-HNATR chelates was developed using a rapid analysis column high performance liquid chromatography equipped with on-line solid phase extraction technique. The samples (Water, human urine, geological samples and soil) were digested by microwave acid-digestion. The palladium, platinum, rhodium

Qiufen Hu; Xiangjun Yang; Zhangjie Huang; Jing Chen; Guangyu Yang

2005-01-01

176

Feature extraction using normalized cross-correlation for pulsed eddy current thermographic images  

NASA Astrophysics Data System (ADS)

Pulsed eddy current (PEC) thermography is an emerging method in the field of non-destructive testing and evaluation (NDT&E). Defects can be characterized by tracking the diffusion of heat in a sample through the analysis of a sequence of PEC thermographic images. This study takes advantage of the capabilities of PEC thermography to gain quantitative information about complex geometrical defects, i.e. angular defect characterization through the analysis of the surface thermal distribution. To conduct the analysis, a new approach using a normalized cross-correlation technique is proposed. The strength of the proposed approach lies in its ability to track the heat diffusion through sequential PEC thermographic images in a metallic sample. The results of the analysis are used to determine the dimensions of defects in the sample under test. These results have shown the effectiveness of the proposed technique in providing features which have good agreement with defect detection and evaluation.

Al-Qubaa, A. R.; Tian, G. Y.; Wilson, J.; Woo, W. L.; Dlay, S. S.

2010-11-01

177

Effect of pulsed electric fields treatment and mash size on extraction and composition of apple juices.  

PubMed

This study explored the effect of pulsed electric field (PEF) treatment (E=450 V/cm; tt=10 ms; E<3 kJ/kg) and apple mash size on juice yield, polyphenolic compounds, sugars, and malic acid. Juice yield increased significantly after PEF treatment of large mash (Y=71.4%) and remained higher than the juice yield obtained for a control small mash (45.6%). The acid sweet balance was not altered by PEF. A correlation was established between the decrease of light absorbance (control: 1.43; treated: 1.10) and the decline of native polyphenols yield due to PEF treatment (control: 9.6%; treated: 5.9% for small mash). An enhanced oxidation of phenolic compounds in cells due to electroporation of the inner cell membrane and the adsorption of the oxidized products on the mash may explain both the lower light absorbance and the lower native polyphenol concentration. PMID:20701245

Turk, Mohammad F; Baron, Alain; Vorobiev, Eugene

2010-09-01

178

Quantification of endogenous brassinosteroids in plant by on-line two-dimensional microscale solid phase extraction-on column derivatization coupled with high performance liquid chromatography-tandem mass spectrometry.  

PubMed

An on-line two-dimensional microscale solid phase extraction (2D?SPE)-on column derivatization (OCD)-high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method was developed for quantification of brassinosteroids (BRs) in plant tissues. Five BRs with widest distribution in plant species and high bioactivity (24-epibrassinolide, 24-epicastasterone, 6-deoxo-24-epicastasterone, teasterone and typhastero) were selected as target analytes. 2D?SPE column packed sequentially with phenyl boronic acid silica sorbent (the first dimension) and C18 silica sorbent (the second dimension) was used to selectively extract and enrich BRs by 110-146 times. OCD was carried out on the second dimension of 2D?SPE column with m-aminophenylboronic acid (m-APBA) as a derivatization reagent, enhancing the sensitivity of MS/MS to BRs by 13-8437 times. It was also found that pre-trap of derivatization reagent on the C18 section of 2D?SPE column could increase reaction efficiency by 3-10 times. The whole process time of the on-line system was less than 30min. The detection limits of the method for five BRs were between 1.4 and 6.6pg with RSDs less than 10%. Endogeneous BRs in tomato leaves were analyzed by using this method. Owing to the high selectivity of this on-line 2D?SPE system, BRs in plant extracts could be quantified using matrix-free standard calibration method with relative recoveries in the range of 80-124%. PMID:23702098

Wu, Qian; Wu, Dapeng; Shen, Zheng; Duan, Chunfeng; Guan, Yafeng

2013-04-22

179

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

180

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

181

A simple and rapid technique for recovery of 99mTc from low specific activity (n,gamma)99Mo based on solid-liquid extraction and column chromatography methodologies.  

PubMed

A simple and inexpensive method has been developed for the separation of (99m)Tc from (99)Mo produced from the neutron activation of (98)Mo by (98)Mo(n,gamma)(99)Mo nuclear reaction. The recovery of (99m)Tc was performed by solid-liquid extraction based on alumina column chromatography. The overall radiochemical yield for the complete separation of (99m)Tc was 85-97% (n=5). The separated Na[(99m)Tc]TcO(4) was of high radionuclidic, radiochemical and chemical purities. The method can be adopted for routine processing and use of (99m)Tc in radiopharmacy operations. PMID:20122663

Chattopadhyay, Sankha; Das, Sujata Saha; Barua, Luna

2009-10-03

182

On-line solid phase extraction system using PTFE packed column for the flame atomic absorption spectrometric determination of copper in water samples  

Microsoft Academic Search

A new flow injection on-line adsorption preconcentration system adapted to flame atomic absorption spectrometry (FAAS) for copper determination at the ?g l?1 level was developed. Polytetrafluoroethylene (PTFE) turnings packed in a mini-column were used as sorbent material. The copper ammonium pyrrolidine dithiocarbamate (APDC) complex was sorbed on the PTFE turnings, from which it could be eluted on-line instantly by isobutyl

Aristidis N. Anthemidis; George A. Zachariadis; John A. Stratis

2001-01-01

183

Efficient energy extraction from large-mode-area, short, heavily Er:Yb codoped phosphate-glass fiber for pulsed laser applications  

NASA Astrophysics Data System (ADS)

Experimental demonstration of an efficient energy extraction from heavily Er:Yb codoped phosphate-glass fiber is reported. In our experiments, sub-20-ns pulses at 1.5 ?m wavelength produced by an actively Q-switched all-fiber oscillator are amplified in 15 cm long, side-pumped phosphate fiber doped with 1 wt % of Er2O3 and 8 wt % of Yb2O3. Two types of active fiber are used, with core diameters of 14 and 25 ?m. The pulse energy achieved with these fibers is 105 and 215 ?J, respectively, with nearly diffraction-limited beam quality. These experiments indicate a potential for further energy scaling beyond the millijoule level by increasing the core size of the fiber.

Polynkin, Pavel; Peyghambarian, N.; Moloney, Jerome

2008-02-01

184

Standardization of Crude Extract of Neem Seed Kernels ( Azadirachta indica A. Juss) and Commercial Neem Based Formulations Using HPTLC and Extended Length Packed-Columns SFC Method  

Microsoft Academic Search

Two chromatographic techniques are described for the separation and quantitative determination of azadirachtin A and B, salannin, and nimbin present in the crude extract of neem seed kernels and commercial neem based formulations. The high performance thin-layer chromatography (HPTLC) separation of markers was carried out on Merck TLC aluminium sheets of silica gel 60 F254 using ethylacetate-benzene (7.0: 3.0, v\\/v)

H. Agrawal; N. Kaul; A. R. Paradkar; K. R. Mahadik

2005-01-01

185

Determination of organochlorine pesticides in propolis by gas chromatography–electron capture detection using double column series solid-phase extraction  

Microsoft Academic Search

A rapid and reliable method was developed and applied for the simultaneous determination of 17 organochlorine pesticides (OCPs)\\u000a in propolis. After extraction with hexane and acetone (1:1, v\\/v), four sorbents (florisil, silica, graphitized carbon, and\\u000a tandem graphitized carbon plus florisil) were assayed for the clean-up step. The elution solvents hexane and ethyl acetate\\u000a (1:1, v\\/v), hexane and dichloromethane (3:7, v\\/v),

Fang Chen; Lanzhen Chen; Qiang Wang; Jinhui Zhou; Xiaofeng Xue; Jing Zhao

2009-01-01

186

Liquid phase separator with chromatographic column.  

PubMed

Presented liquid phase separator with integrated chromatographic column enables the separation and treatment of a solvent extract layer after the extraction of organic compounds from water in one simple run in a single piece of glassware. The separator has been successfully applied for the determination of hydrocarbon oil index in waters. PMID:15628145

Mikita, Martin; Tölgyessy, Peter; Hrivnák, Peter

2004-12-01

187

Ovipositional responses of the pulse beetle, Bruchus chinensis (Coleoptera: Bruchidae) to extracts and compounds of Capparis decidua.  

PubMed

Extracts of Capparis decidua stems and flowers showed insecticidal and oviposition inhibitory activities against Bruchus chinensis. The LC50 values of these extracts were found to increase with the increase in the polarity of the extract at different exposure periods. For instance, after 96 h, the LC50 values were found to be 3.619, 7.319, and 10.151 microg for CD1, CD2, and CD3, respectively. Extract CD7 was effective only at higher doses. The toxicity was found to be dose- and time-dependent. The females laid lesser number of eggs, when exposed to sublethal doses of different extracts and pure compounds, as compared to control. The maximum oviposition deterrence index was found for extract CD1 followed in decreasing order by CD2, CD3, and CD7. From extract CD1, two compounds were isolated and characterized as triacontanol (C1) and 2-carboxy-1,1-dimethylpyrrolidine (C2). When the females were exposed to sublethal doses of these compounds, they laid lesser number of eggs as compared to the control. C2 was found to have a slightly greater oviposition inhibition effect than C1. From fraction CD7, one novel compound labeled as CDF1 has been isolated and identified as 6-(1-hydroxy-non-3-enyl)tetrahydropyran-2-one. CDF1 has also shown insecticidal and oviposition inhibitory activities against B. chinensis at low concentrations. PMID:17177496

Upadhyay, Ravi K; Rohatgi, Leena; Chaubey, Mukesh K; Jain, Subhash C

2006-12-27

188

Quantitative analysis of the hydrogen peroxide formed in aqueous cigarette tar extracts  

Microsoft Academic Search

We have established, for the first time, a reliable method to quantitate hydrogen peroxide (HâOâ) generated in aqueous extracts of cigarette smoke tar. The aqueous tar extract was passed through a short reverse-phase column and its HâOâ concentration determined by differential pulse polarography using an automatic reference subtraction system. The HâOâ concentration increased with aging, pH and temperature; the presence

T. Nakayama; D. F. Church; W. A. Pryor

1989-01-01

189

Plasma Column Generation Study.  

National Technical Information Service (NTIS)

A study has been conducted on methods of producing unconfined plasma columns of length one to twenty meters in air at atmospheric pressure. Turbulent combustion gas jet and flammable liquid jets were considered for producing the plasma columns, which were...

P. S. Masser W. Cramer R. E. Petersen A. J. Hoehn E. K. Parks

1969-01-01

190

Petroleum mass removal from low permeability sediment using air sparging\\/soil vapor extraction: impact of continuous or pulsed operation  

Microsoft Academic Search

Air sparging and soil vapor extraction (AS\\/SVE) are innovative remediation techniques that utilize volatilization and microbial degradation to remediate petroleum spills from soils and groundwater. This in situ study investigated the use of AS\\/SVE to remediate a gasoline spill from a leaking underground storage tank (UST) in the low permeability, clayey soil of the Appalachian Piedmont. The objectives of this

Brian C. Kirtland; C. Marjorie Aelion

2000-01-01

191

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

192

Simplified distillation column controls  

SciTech Connect

A simple, energy efficient method of controlling single or double distillation columns for the production of ethyl alcohol is described. The control system is based on a material balance scheme centered around a thermostat actuated control valve to regulate reflux rate and product purity. Column bottom's levels are automatically regulated by vented suction lines on the pump inlets. Methods of minimizing control input variations are used including column insulation, stillage-to-beer heat exchanger, and a steam pressure regulator.

Badger, P.; Pile, R.; Lightsey, G.

1984-01-01

193

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

194

Diabatic column optimization compared to isoforce columns  

Microsoft Academic Search

This paper analyzes and compares optimization results for simulated diabetic columns to theoretically derived optimization results from the isoforce method for the same system. The separation of ethanol and water is used to illustrate the two methods and bring out their common and special features. The results, which are presented in McCabe-Thiele diagrams, show partial compatibility between the methods. The

Erik Sauar; Ricardo Rivero; Signe Kjelstrup; Kristian M. Lien

1997-01-01

195

DNA Extraction Columns Contaminated with Murine Sequences  

Microsoft Academic Search

Sequences of the novel gammaretrovirus, xenotropic murine leukemia virus-related virus (XMRV) have been described in human prostate cancer tissue, although the amounts of DNA are low. Furthermore, XMRV sequences and polytropic (p) murine leukemia viruses (MLVs) have been reported in patients with chronic fatigue syndrome (CFS). In assessing the prevalence of XMRV in prostate cancer tissue samples we discovered that

Otto Erlwein; Mark J. Robinson; Simon Dustan; Jonathan Weber; Steve Kaye; Myra O. McClure

2011-01-01

196

Nondestructive evaluation of the preservation state of stone columns in the Hospital Real of Granada  

Microsoft Academic Search

This paper describes the results of the employment of two nondestructive evaluation methods for the diagnostic of the preservation state of stone elements. The first method is based on ultrasonic (US) pulses while the second method uses short electromagnetic pulses. Specifically, these methods were applied to some columns, some of them previously restored. These columns are part of the architectonic

C. Moreno de Jong van Coevorden; C. Cobos Sánchez; A. Rubio Bretones; M. Fernández Pantoja; Salvador G. García; R. Gómez Martín

2012-01-01

197

Modeling of column flotation  

Microsoft Academic Search

Many investigators believe that column flotation cells offer significant advantages over standard mechanical machines for the flotation of fine particles. However, because of their unique design and operation, conventional techniques for flotation cell scale-up and design cannot be applied to columns. In an attempt to help alleviate this problem, a population balance model based on first principles has been developed

G. H. Luttrell; G. T. Adel; R. H. Yoon

1987-01-01

198

Modeling of column flotation  

SciTech Connect

Many investigators believe that column flotation cells offer significant advantages over standard mechanical machines for the flotation of fine particles. However, because of their unique design and operation, conventional techniques for flotation cell scale-up and design cannot be applied to columns. In an attempt to help alleviate this problem, a population balance model based on first principles has been developed for fine particle flotation in a column. Two different terms have been considered in the model, i.e., transport and rate. Transport terms, incorporating fluid flow and buoyancy, are used to describe the movement of air bubbles, unattached particles and bubble-particle aggregates along the length of the column. Rate terms, which describe the bubble-particle attachment process, have been derived from first principle considerations. Because the model is based on first principles, it can be useful for the design, control, optimization and scale-up of column flotation cells. 9 refs., 12 figs.

Luttrell, G.H.; Adel, G.T.; Yoon, R.H.

1987-01-01

199

JCE Feature Columns  

NASA Astrophysics Data System (ADS)

The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad in the Chemistry Curriculum, and WWW Site Review. These columns differ from the print feature columns in that they use the Internet as the publication medium. Doing so allows these features to include continually updated information, digital components, and links to other online resources. The Conceptual Questions and Challenge Problems feature of JCE Internet serves as a good example for the kinds of resources that you can expect to find in an online feature column. Like other columns it contains a mission statement that defines the role of the column. It includes a digital library of continually updated examples of conceptual questions and challenge problems. (As I write this we have just added several new questions to the library.) It also includes a list of links to related online resources, information for authors about how to write questions and problems, and information for teachers about how to use conceptual questions and challenge problems. Teaching with Technology home page at JCE Online. One-Stop Feature Shop The updated Feature area of JCE Online offers information about all JCE feature columns in one place. It gives you a quick and convenient way to access a group of articles in a particular subject area. It provides authors and readers with a good definition of the column and its mission. It complements the print feature columns with online resources. It provides up-to-date bibliographies for selected areas of interest. And last, but not least, it provides that email address you can use to send that message of appreciation to the feature editor for his or her contribution to JCE and the chemical education community.

Holmes, Jon L.

1999-05-01

200

Development and validation of a multi-residue method for pesticide determination in honey using on-column liquid-liquid extraction and liquid chromatography-tandem mass spectrometry.  

PubMed

We report on the development and validation under ISO 17025 criteria of a multi-residue confirmatory method to identify and quantify 17 widely chemically different pesticides (insecticides: Carbofuran, Methiocarb, Pirimicarb, Dimethoate, Fipronil, Imidacloprid; herbicides: Amidosulfuron, Rimsulfuron, Atrazine, Simazine, Chloroturon, Linuron, Isoxaflutole, Metosulam; fungicides: Diethofencarb) and 2 metabolites (Methiocarb sulfoxide and 2-Hydroxytertbutylazine) in honey. This method is based on an on-column liquid-liquid extraction (OCLLE) using diatomaceous earth as inert solid support and liquid chromatography (LC) coupled to mass spectrometry (MS) operating in tandem mode (MS/MS). Method specificity is ensured by checking retention time and theoretical ratio between two transitions from a single precursor ion. Linearity is demonstrated all along the range of concentration that was investigated, from 0.1 to 20 ng g(-1) raw honey, with correlation coefficients ranging from 0.921 to 0.999, depending on chemicals. Recovery rates obtained on home-made quality control samples are between 71 and 90%, well above the range defined by the EC/657/2002 document, but in the range we had fixed to ensure proper quantification, as levels found in real samples could not be corrected for recovery rates. Reproducibility is found to be between 8 and 27%. Calculated CCalpha and CCbeta (0.0002-0.943 ng g(-1) for CCalpha, and 0.0002-1.232 ng g(-1) for CCbeta) show the good sensitivity attained by this multi-residue analytical method. The robustness of the method has been tested in analyzing more than 100 raw honey samples collected from different areas in Belgium, as well as some wax and bee samples, with a slightly adapted procedure. PMID:17416380

Pirard, C; Widart, J; Nguyen, B K; Deleuze, C; Heudt, L; Haubruge, E; De Pauw, E; Focant, J-F

2007-03-16

201

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

202

IMMUNOAFFINITY COLUMN FOR ISOLATION OF BIOACTIVE COMPOUNDS USING MONOCLONAL ANTIBODIES  

Microsoft Academic Search

Anti-solamargine and anti-ginsenoside Rb1 monoclonal antibodies were used for preparation of an immunoaffinity column. Total solasodine glycosides were separated directly from the crude extract of Solanum khasianum fruit, by the established immunoaffinity column. This method was specific for solasodine glycosides, which was detected by thin layer chromatography and eastern blotting. An immunoaffinity column, using anti-ginsenoside Rb1 monoclonal antibody, has made

Waraporn Putalun; Noriko Fukuda; Hiroyuki Tanaka; Yukihiro Shoyama

2002-01-01

203

Composite Column Design  

NSDL National Science Digital Library

This module, created by Craig Johnson of Central Washington University, "incorporates engineering design (using smart spreadsheets) into a laboratory activity focusing on columns made of composite materials." In this lab, students will simulate the use of composite columns and use spreadsheets to optimize design for engineering performance. The module features an abstract, objective, curriculum overview, procedures, mathematical calculations and references. The objectives of the module are to design appropriate composite column structures, fabricate composite using appropriate methods and critically evaluate composite's performance referencing predications. This is a great resource to either enhance or create new curriculum for instructors.

Johnson, Craig

2009-09-30

204

Differential pulse polarographic determination of tin in alloys and environmental samples after preconcentration with the ion pair of 2-nitroso-1-naphthol-4-sulfonic acid and tetradecyldimethylbenzylammonium chloride onto microcrystalline naphthalene or by column method  

Microsoft Academic Search

A highly selective, sensitive, rapid and economical differential pulse polarographic method has been developed for the determination of trace amount of tin in various standard alloys and environmental samples after adsorption of its 2-nitroso-1-naphthol-4-sulfonic acid-tetradecyldimethylbenzylammonium chloride on microcrystalline naphthalene in the pH range of 8.7–10.6. After filtration, the solid mass is shaken with 8–10 ml of 3.5 M hydrochloric acid

Mohammad Ali Taher; Bal Krishan Puri

1999-01-01

205

Tevatron Extraction Microcomputer.  

National Technical Information Service (NTIS)

Extraction in the Fermilab Tevatron is controlled by a multi-processor Multibus microcomputer system called QXR (Quad eXtraction Regulator). QXR monitors several analog beam signals and controls three sets of power supplies: the ''bucker'' and ''pulse'' m...

L. Chapman D. A. Finley M. Harrison W. Merz

1985-01-01

206

Nonequilibrium Positive Column III.  

NASA Astrophysics Data System (ADS)

Previous work has shown that the first principles nonlocal kinetic method [1] is closely approximated by the nonlocal moment method [2] in positive column analysis, and that the transition from nonequilibrium to equilibrium at sufficiently high NR (gas density × radius) can be studied by the nonlocal moment method [3]. The present paper describes the derivation of a quantitative condition that the parameter NR must satisfy in order for local equilibrium to prevail in the low pressure positive column discharge. The derivation is based on the electron energy balance equation resulting from the two-term Legendre expansion technique of solving the Boltzmann equation for the electron energy distribution function. Use of the quantitative condition is illustrated by application to a positive column discharge in neon. [1]D. Uhrlandt and R. Winkler, J. Phys. D 29, 115 (1996). [2]J. H. Ingold, Phys. Rev. E 56, 5932 (1997). [3]J. H. Ingold, Bull. Am. Phys. Soc. 43, 1466 (1998).

Ingold, J. H.

1999-10-01

207

Extractive Distillation: A Review  

Microsoft Academic Search

Extractive distillation is more and more commonly applied in industry, and becomes an important separation method in chemical engineering. This paper provides an in?depth review for extractive distillation. Separation sequence of the columns, combination with other separation processes, tray configuration and operation policy are included in process of extractive distillation. Since the solvent plays an important role in the design

Zhigang Lei; Chengyue Li; Biaohua Chen

2003-01-01

208

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

209

A Column Dispersion Experiment.  

ERIC Educational Resources Information Center

|Crushed glass and a Rhodamine B solution are used in a one-dimensional optically scanned column experiment to study the dispersion phenomenon in porous media. Results indicate that the described model gave satisfactory results and that the dispersion process in this experiment is basically convective. (DC)|

Corapcioglu, M. Y.; Koroglu, F.

1982-01-01

210

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

211

In-situ differential pulse anodic stripping voltammetry combined with hollow fiber-based liquid-three phase micro extraction for determination of mercury using Au-nanoparticles sol-gel modified Pt-wire.  

PubMed

A new method has been proposed based on hollow fiber-based liquid three-phase micro extraction and in-situ differential pulse anodic stripping voltammetry (DPASV) for the micro extraction and quantification of mercury(II) ions. Different factors affecting the liquid-three phases micro extraction, including organic solvent, pH of the donor and acceptor phases, concentration of the complexing agent, extraction time, and stirring rate were investigated and the optimal extraction conditions were established. Three microelectrodes designed and constructed for this study were inserted into the two ends of a hollow fiber inside the acceptor solution, and then voltammetric analysis was performed in-situ during the extraction time. After 1600 s, final stable signal was used for the analytical applications. Under the optimized conditions, an enrichment factor of 277 was achieved and the relative standard deviation (R.S.D.) of the method was 6.2% (n=5). The calibration curve was obtained in the range of 0.2-30.0 nmol L(-1) Hg(II) with a reasonable linearity (R(2)>0.9880) and a limit of detection of 0.06 nmol L(-1). Finally, the applicability of the proposed method was evaluated by extraction and determination of mercury in real samples such as fish and rice. PMID:22967561

Ensafi, Ali A; Allafchian, Ali R; Saraji, M; Farajmand, B

2012-06-04

212

Development of novel contactor for nuclear solvent extraction  

SciTech Connect

For current designs of radiochemical plants, solvent-extraction contactors with no periodic maintenance like pulse column are the first choice. In addition, as costs of specialty solvents for nuclear extraction are quite high, there is a demand for operation at extreme phase ratios. Recently a novel mixer-settler was visualized and developed for this kind of service. The mixer of the novel contactor is based on rotated helical tubes and does not involve any mechanical moving part. Mass-transfer runs were carried out with aqueous nitric acid and 30% TBP solvent at A/O of 0.25-200 (in extraction) and A/O of 0.25-10 (in back-extraction mode). The developed contactor exhibited nearly 100% efficiency for all the cases. (authors)

Kumar, Shekhar; Kumar, Rajnish; Sivakumar, D.; Balamurugan, M.; Koganti, S.B. [Reprocessing R and D Division, Reprocessing Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

2008-07-01

213

Modified Purex first-cycle extraction for neptunium recovery  

SciTech Connect

A new PUREX first-cycle flowsheet was devised to enhance the extraction yield of neptunium at the extraction step of this cycle. Simulation results (using a qualified process-simulation tool), le d to raising the nitric acid concentration of the feed from 3 M to 4.5 M to allow extraction of more than 99% of the neptunium. This flowsheet was operated in the shielded process cell of ATALANTE facility using pulsed columns and mixer-settlers banks. A 15 kg quantity of genuine oxide fuel of average burn up of 52 GWd/t with cooling time of nearly five years was treated, and the neptunium extraction yield obtained was greater than 99.6%. (authors)

Dinh, Binh; Moisy, Philippe; Baron, Pascal; Calor, Jean-Noel; Espinoux, Denis; Lorrain, Brigitte; Benchikouhne-Ranchoux, Magali [Departement de radiochimie et procedes, Commissariat a l'energie atomique, Centre de Valrho BP 17171 30207, Bagnols-sur-Ceze CEDEX (France)

2008-07-01

214

4. TYPICAL COLUMN BASE (COLUMN #1 ON PHOTO ELEVATION PLAN) ...  

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

4. TYPICAL COLUMN BASE (COLUMN #1 ON PHOTO ELEVATION PLAN) FACING SOUTH. - U.S. Naval Base, Pearl Harbor, Signal Tower, Corner of Seventh Street & Avenue D east of Drydock No. 1, Pearl City, Honolulu County, HI

215

11. TIMBER COLUMN AND CAST IRON COLUMN CAP IN FIFTH ...  

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

11. TIMBER COLUMN AND CAST IRON COLUMN CAP IN FIFTH FLOOR WAREHOUSE SPACE. VIEW TO SOUTHWEST. - Commercial & Industrial Buildings, Becker-Hazelton Company Warehouse, 280 Iowa Street, Dubuque, Dubuque County, IA

216

43. Details of Columns / Details of Column Splice / ...  

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

43. Details of Columns / Details of Column Splice / Detail of Concrete Ceiling at Walls on 2nd Floor (drawing S9) - Whittier State School, Hospital & Receiving Building, 11850 East Whittier Boulevard, Whittier, Los Angeles County, CA

217

Nonequilibrium Positive Column II.  

NASA Astrophysics Data System (ADS)

Previous work has shown that the first principles nonlocal kinetic method [1] is closely approximated by the nonlocal moment method [2] in positive column analysis. In the present paper, the nonlocal moment method is compared with two of the most often used local moment methods: (i) local moment method with Maxwell EEDF; (ii) local moment method with 0D EEDF. The form of the Boltzmann equation for electrons in a positive column discharge suggests that each gas has a characteristic curve of positive column E/N versus NR (E is axial electric field, N is gas density, and R is tube radius). This characteristic curve affords a systematic way of comparing various methods because its course depends on the form of the EEDF used to calculate transport coefficients and inelastic collision rates, on whether or not it is assumed that the electrons are in equilibrium with the axial field, on whether or not ion inertia is taken into account, etc. Using an argon-like gas for illustration, it is shown that the characteristic curve based on equilibrium with 0D EEDF is a poor approximation to that based on nonequilibrium for NR less than 1× 10^17 cm-2 (PR<3 Torr-cm), while that based on equilibrium with Maxwell EEDF is an extremely poor approximation at any value of NR. [1]D. Uhrlandt and R. Winkler, J. Phys. D 29, 115 (1996). [2]J. H. Ingold, Phys. Rev. E 56, 5932 (1997).

Ingold, John H.

1998-10-01

218

Preconcentration of lead complexed with O, O-diethyl-dithiophosphate by column solid-phase extraction using different sorbents in a flow injection system coupled to a flame atomic absorption spectrometer  

Microsoft Academic Search

A comparative study of C18 immobilized on silica, activated carbon and a polyurethane foam, as sorbents for Pb complexed with O,O-diethyl-dithiophosphate in a flow injection preconcentration system is reported. The complex was formed in 1.0 M HCl medium and processed in a simple system using a peristaltic pump, a manual injector–commutator and a mini-column filled with the sorbent. Using ethanol

Sueli Pércio Quináia; José Bento Borba da Silva; Maria do Carmo Ezequiel Rollemberg; Adilson José Curtius

2001-01-01

219

Development and validation of a multi-residue method for pesticide determination in honey using on-column liquid–liquid extraction and liquid chromatography–tandem mass spectrometry  

Microsoft Academic Search

We report on the development and validation under ISO 17025 criteria of a multi-residue confirmatory method to identify and quantify 17 widely chemically different pesticides (insecticides: Carbofuran, Methiocarb, Pirimicarb, Dimethoate, Fipronil, Imidacloprid; herbicides: Amidosulfuron, Rimsulfuron, Atrazine, Simazine, Chloroturon, Linuron, Isoxaflutole, Metosulam; fungicides: Diethofencarb) and 2 metabolites (Methiocarb sulfoxide and 2-Hydroxytertbutylazine) in honey. This method is based on an on-column liquid–liquid

C. Pirard; J. Widart; B. K. Nguyen; C. Deleuze; L. Heudt; E. Haubruge; E. De Pauw; J.-F. Focant

2007-01-01

220

IMPACT RESPONSE AND PARAMETRIC STUDIES OF REINFORCED CONCRETE CIRCULAR COLUMNS  

Microsoft Academic Search

This paper presents a detailed description of the influence of critical parameters that govern the vulnerability of columns under lateral impact loads. Numerical simulations are conducted by using the Finite Element program LS-DYNA, incorporating steel reinforcement, material models and strain rate effects. A simplified method based on impact pulse generated from full scale impact tests is used for impact reconstruction

221

Narrow-bore high performance liquid chromatographic method for the determination of cetirizine in human plasma using column switching  

Microsoft Academic Search

An improved column switching high performance liquid chromatographic (HPLC) method was developed for determination of cetirizine in human plasma. Plasma samples were prepared by liquid–liquid extraction using methylene chloride. The samples extracted were initially injected into a clean-up Capcell Pak MF C8 column and the peaks of cetirizine and internal standard were separated to an analytical C18 micro-column via column

Chong-Kook Kim; Kyu Jeong Yeon; Eunmi Ban; Myung-Ja Hyun; Jin-Ki Kim; Mee-Kyung Kim; Su-Eon Jin; Jeong-Sook Park

2005-01-01

222

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

2012-08-27

223

3 HPLC columns and packings  

Microsoft Academic Search

In this chapter on HPLC columns, we are discussing both the surface chemistry of a packing as well as column design and performance. In the section that covers column chemistry, we cover modern options of base materials as well as the commonly used approaches towards the surface chemistry of a packing. Specific subsections are dedicated to the selectivity of reversed-phase

Uwe D. Neue; Bonnie A. Alden; Edward R. Grover; Eric S. Grumbach; Pamela C. Iraneta; Alberto Méndez

2007-01-01

224

4 HPLC columns for pharmaceutical analysis  

Microsoft Academic Search

This chapter deals with the properties of high-pressure liquid chromatography columns. It is divided into two sections: column physics and column chemistry. In the section on column physics, we discuss the properties that influence column performance, such as particle size, column length and column diameter, together with the effect of instrumentation on the quality of a separation. In the section

Uwe D. Neue; Bonnie A. Alden; Pamela C. Iraneta; Alberto Méndez; Eric S. Grumbach; Kimvan Tran; Diane M. Diehl

2005-01-01

225

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

2011-07-27

226

Automated sample preparation with extraction columns by means of anti-isoproturon immunosorbents for the determination of phenylurea herbicides in water followed by liquid chromatography–diode array detection and liquid chromatography–atmospheric pressure chemical ionization mass spectrometry  

Microsoft Academic Search

The retention of five phenylurea herbicides (chlorotoluron, isoproturon, diuron, linuron and diflubenzuron) was evaluated by solid-phase extraction with an automated sample preparation (ASPEC) system using anti-isoproturon immunosorbents. The extraction was carried out after the percolation of 50 ml of LC-grade water and groundwater samples spiked with a mixture of the five pesticides at the ppb level and then elution with

I Ferrer; V Pichon; M.-C Hennion; D Barceló

1997-01-01

227

Dynamic NMR microscopy of chromatographic columns  

SciTech Connect

Pulsed magnetic field gradients encoded a discrete spatial and temporal motion of the molecules of a fluid percolating through the packed bed of a dynamic radial compression column for liquid chromatography. Two packing materials of porous, chemically bonded C18 silica were used; large irregularly shaped particles (55--105 {micro}m) and small spherical particles (6 {micro}m). By combining pulsed field gradient NMR and NMR imaging the distribution of the fluid dynamic displacement probability was determined quantitatively at each point of the static image space. The local axial dispersion coefficient, fluid velocity, and external porosity of the bed were also estimated. The resolution achieved was 250 {micro}m {times} 250 {micro}m {times} 2,500 {micro}m per voxel, corresponding to a 250 {micro}m {times} 250 {micro}m pixel in a 2.5-mm-thick slice. Irregularly shaped particles showed slight external porosity heterogeneities over the column cross section, causing a dramatic loss of performance. Spherically shaped particles offered a nearly planar distribution of the transport characteristics across the packed bed, making radial compression of the bed enhance the performance.

Tallarek, U.; Bayer, E. [Univ. of Tuebingen (Germany). Inst. of Organic Chemistry; Dusschoten, D. van; Scheenen, T.; Van As, H. [Wageningen Agricultural Univ. (Netherlands). Dept. of Molecular Physics]|[Wageningen NMR Center (Netherlands); Guiochon, G. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States). Chemical and Analytical Sciences Div.; Neue, U.D. [Waters Corp., Milford, MA (United States)

1998-09-01

228

Nonequilibrium positive column  

SciTech Connect

The dc positive column is modeled with a system of balance equations based on moments of the radially dependent Boltzmann equation taken after the two-term Legendre expansion of the electron energy distribution function is made. The importance of the electron energy balance equation, which is frequently ignored in positive column analysis, is emphasized. A key assumption is that electron transport coefficients and collision frequencies in the nonequilibrium regime have the same relation to the average energy as in the equilibrium regime, according to a zero-dimensional Boltzmann solution for a particular value of average energy. Because of this assumption, the model makes a smooth transition to the traditional equilibrium model with radially constant average energy at sufficiently high pressure. Model results in the nonequilibrium regime agree closely with published results of a numerical solution of the one-dimensional Boltzmann equation, including results for radial heat flow in the electron gas with radially varying average energy. It is shown that three separate processes account for radial heat flow: convection, conduction, and diffusion. In the example chosen for illustration of the method, the convection component is small, while the conduction and diffusion components are large and opposite in direction, nearly canceling each other. {copyright} {ital 1997} {ital The American Physical Society}

Ingold, J.H. [One Bratenahl Place, Suite 610, Cleveland, Ohio 44108 (United States)

1997-11-01

229

Measurement of bromate in bread by high performance liquid chromatography with post?column flow reactor detection  

Microsoft Academic Search

An analytical procedure was developed to measure bromate residues in baked goods using a sequence of clean?up procedures followed by high performance liquid chromatography (HPLC) with a post?column reaction for oxidants. Deionized water was used to extract bromate from bread samples. The extract was treated with a C?18 solid phase extraction column to remove lipids, a cation exchange column with

Katsuichi Himata; Masaaki Noda; Susumu Ando; Yuji Yamada

1997-01-01

230

Bioanalytical liquid chromatography tandem mass spectrometry methods on underivatized silica columns with aqueous\\/organic mobile phases  

Microsoft Academic Search

This review article summarizes the recent progress on bioanalytical LC–MS\\/MS methods using underivatized silica columns and aqueous\\/organic mobile phases. Various types of polar analytes were extracted by using protein precipitation (PP), liquid\\/liquid extraction (LLE) or solid-phase extraction (SPE) and were then analyzed using LC–MS\\/MS on the silica columns. Use of silica columns and aqueous\\/organic mobile phases could significantly enhance LC–MS\\/MS

Weng Naidong

2003-01-01

231

Stability of Column-Supported Embankments.  

National Technical Information Service (NTIS)

Column-supported embankments have a great potential for application in the coastal regions of Virginia, where highway embankments are often constructed on soft ground. The columns can be driven piles, vibro-concrete columns, deepmixing- method columns, st...

G. M. Filz M. P. Navin

2006-01-01

232

PULSE SORTER  

DOEpatents

An apparatus is described for counting and recording the number of electrical pulses occurring in each of a timed sequence of groups of pulses. The particular feature of the invention resides in a novel timing circuit of the univibrator type which provides very accurately timed pulses for opening each of a series of coincidence channels in sequence. The univibrator is shown incorporated in a pulse analyzing system wherein a series of pulse counting channels are periodically opened in order, one at a time, for a predetermtned open time interval, so that only one channel will be open at the time of occurrence of any of the electrical pulses to be sorted.

Wade, E.J.

1958-07-29

233

Modeling seismic stimulation: Enhanced non-aqueous fluid extraction from saturated porous media under pore-pressure pulsing at low frequencies  

NASA Astrophysics Data System (ADS)

Seismic stimulation, the application of low-frequency stress-pulsing to the boundary of a porous medium containing water and a non-aqueous fluid to enhance the removal of the latter, shows great promise for both contaminated groundwater remediation and enhanced oil recovery, but theory to elucidate the underlying mechanisms lag significantly behind the progress achieved in experimental research. We address this conceptual lacuna by formulating a boundary-value problem to describe pore-pressure pulsing at seismic frequencies that is based on the continuum theory of poroelasticity for an elastic porous medium permeated by two immiscible fluids. An exact analytical solution is presented that is applied numerically using elasticity parameters and hydraulic data relevant to recent proof-of-principle laboratory experiments investigating the stimulation-induced mobilization of trichloroethene (TCE) in water flowing through a compressed sand core. The numerical results indicated that significant stimulation-induced increases of the TCE concentration in effluent can be expected from pore-pressure pulsing in the frequency range of 25-100 Hz, which is in good agreement with what was observed in the laboratory experiments. Sensitivity analysis of our numerical results revealed that the TCE concentration in the effluent increases with the porous medium framework compressibility and the pulsing pressure. Increasing compressibility also leads to an optimal stimulation response at lower frequencies, whereas changing the pulsing pressure does not affect the optimal stimulation frequency. Within the context of our model, the dominant physical cause for enhancement of non-aqueous fluid mobility by seismic stimulation is the dilatory motion of the porous medium in which the solid and fluid phases undergo opposite displacements, resulting in stress-induced changes of the pore volume.

Lo, Wei-Cheng; Sposito, Garrison; Huang, Yu-Han

2012-03-01

234

Integration of monolithic frit into the particulate capillary (IMFPC) column in shotgun proteome analysis.  

PubMed

Capillary column plays an important role in nano-flow liquid chromatography coupled with tandem mass spectrometry for dealing with the high dynamic range and complexity of protein samples in shotgun proteome analysis. In this study, the integrated monolithic frit into the particulate capillary (IMFPC) column was prepared. By comparing the prepared IMFPC column with conventionally fritless capillary column, smaller size of packing materials could be easily packed into the capillary to achieve higher average peak capacity and proteome coverage. As the monolithic emitter was integrated onto this type of column, the void volume between packing particles and electrospray emitter was eliminated and the electrospray quality was improved. The prepared IMFPC column was applied to proteome analysis of mouse liver extracts, and it was observed that the number of identified proteins and peptides increased 14.9 and 12.9% as well as the peak capacity increased 11.6% by using IMFPC column over conventionally fritless capillary column. PMID:19786199

Wang, Fangjun; Dong, Jing; Ye, Mingliang; Wu, Ren'an; Zou, Hanfa

2009-07-04

235

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

236

Properties and plasticity of synaptic inputs to rat dorsal column neurones recorded in vitro  

PubMed Central

The mechanisms regulating the flow of sensory signals and their modification by synaptic interactions in the dorsal column nuclei are incompletely understood. Therefore, we examined the interactions between EPSPs evoked by stimulation of dorsal column and corticofugal fibres in the dorsal column nuclei cells using an in vitro slice technique. Dorsal column EPSPs had briefer durations at depolarised membrane potentials than corticofugal EPSPs. Superfusion of the NMDA receptor antagonist 2d(-)-2-amino-5-phosphonovaleric acid (AP5) did not modify dorsal column EPSPs but reduced corticofugal EPSPs. Application of the AMPA/kainate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) abolished both dorsal column and corticofugal EPSPs in cells held at the resting potential. Therefore, dorsal column EPSPs were mediated by non-NMDA receptors but corticofugal EPSPs revealed both non-NMDA- and NMDA-dependent components. Paired-pulse stimulation of dorsal column fibres elicited a depression of the second EPSP at pulse intervals of < 50 ms; however, paired-pulse stimulation of corticofugal fibres evoked facilitation of the second EPSP at pulse intervals of < 30 ms. When stimulation of the corticofugal fibres preceded stimulation of the dorsal column fibres, facilitation of the dorsal column EPSP was observed at pulse intervals of < 100 ms. This facilitation was blocked at hyperpolarised membrane potentials or in the presence of AP5, suggesting activation of NMDA receptors. There was a depression of corticofugal EPSPs by previous dorsal column stimulation. Dorsal column EPSPs were gradually depressed during stimulation with barrages at frequencies of > 10 Hz, while corticofugal EPSPs were facilitated and summated at frequencies > 30 Hz. Hyperpolarisation and application of AP5 prevented the facilitation of corticofugal EPSPs. High frequency stimulation of the corticofugal input elicited a short-lasting AP5-sensitive facilitation of both corticofugal and dorsal column EPSPs. Depolarising current facilitated dorsal column EPSPs but not corticofugal EPSPs. These results indicate that synaptic interactions include different forms of activity-dependent synaptic plasticity, with the participation of NMDA receptors and probably Ca2+ inflow through voltage-gated channels. These complex synaptic interactions may represent the cellular substrate of the integrative function of the dorsal column nuclei observed in vivo.

Nunez, Angel; Buno, Washington

2001-01-01

237

45. MAIN MEETING ROOM COLUMNS. Ends of gallery columns identified ...  

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

45. MAIN MEETING ROOM COLUMNS. Ends of gallery columns identified at the time of removal for transfer to the George School for re-erection. The stamp reads, 'REMOVED FROM 12th ST. MTG HSE PHILA 1972'. - Twelfth Street Meeting House, 20 South Twelfth Street, Philadelphia, Philadelphia County, PA

238

Molten salt extractive distillation process for zirconium-hafnium separation  

Microsoft Academic Search

This patent describes an improvement in a process for zirconium-hafnium separation. It utilizes an extractive distillation column with a mixture of zirconium and hafnium tetrachlorides introduced into a distillation column having a top and bottom with hafnium enriched overheads taken from the top of the column and a molten salt solvent circulated through the column to provide a liquid phase,

D. F. McLaughlin; R. A. Stoltz

1989-01-01

239

Effect of soil permeability on virus removal through soil columns.  

PubMed Central

Laboratory experiments were performed on four different soils, using 100 cm long columns, to determine the extent of virus movement when wastewater percolated through the soils at various hydraulic flow rates. Unchlorinated secondary sewage effluent seeded with either poliovirus type 1 (strain LSc) or echovirus type 1 (isolate V239) was continuously applied to soil columns for 3 to 4 days at constant flow rates. Water samples were extracted daily from ceramic samplers at various depths of the column for the virus assay. The effectiveness of virus removal from wastewater varied greatly among the different soil types but appeared to be largely related to hydraulic flow rates. At a flow rate of 33 cm/day, Anthony sandy loam removed 99% of seeded poliovirus within the first 7 cm of the column. At flow rates of 300 cm/day and above, Rubicon sand gave the poorest removal of viruses; less than 90% of the seeded viruses were removed by passage of effluent through the entire length of the soil column. By linear regression analyses, the rate of virus removal in soil columns was found to be negatively correlated with the flow of the percolating sewage effluent. There was no significant difference in rate of removal between poliovirus and echovirus in soil columns 87 cm long. The rate of virus removal in the upper 17 cm of the soil column was found to be significantly greater than in the lower depths of the soil column. This study suggests that the flow rate of water through the soil may be the most important factor in predicting the potential of virus movement into the groundwater. Furthermore, the length of the soil column is critical in obtaining useful data to predict virus movement into groundwater.

Wang, D S; Gerba, C P; Lance, J C

1981-01-01

240

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

241

Column liquid chromatography  

SciTech Connect

This review covers the fundamental developments in the field of column liquid chromatography (LC) during the period of 1984-1985. In an attempt to conserve space, patents and theses have been excluded. Only articles published in English, French, German, and Russian with some exceptions have been included. As compared to the previous review (Anal. Chem. 1984, 56, 300R-340R), all of the tables dealing with selected applications have been deleted and sections on automation and data handling, ion chromatography, trace analysis and sample preparation, and novel applications have been included. New sections that have been added are hydrophobic interaction chromatography, micellar mobile phases, fast LC, and indirect photometric direction. This review is not a comprehensive coverage of all LC literature. The attempt has been made to critically select only those references that reflect fundamental developments in LC theory, methodology, and instrumentation. The main data base for this review was CA Selects (HPLC and GPC) from October 31, 1983, to December 2, 1985. This represented over 8000 abstracts of which 1200 were used. In addition, each author used other search routines to augment coverage from CA Selects. 195 references.

Barth, H.G.; Barber, W.E.; Lochmueller, C.H.; Majors, R.E; Regnier, F.E.

1986-04-01

242

Dorsal column stimulator applications  

PubMed Central

Background: Spinal cord stimulation (SCS) has been used to treat neuropathic pain since 1967. Following that, technological progress, among other advances, helped SCS become an effective tool to reduce pain. Methods: This article is a non-systematic review of the mechanism of action, indications, results, programming parameters, complications, and cost-effectiveness of SCS. Results: In spite of the existence of several studies that try to prove the mechanism of action of SCS, it still remains unknown. The mechanism of action of SCS would be based on the antidromic activation of the dorsal column fibers, which activate the inhibitory interneurons within the dorsal horn. At present, the indications of SCS are being revised constantly, while new applications are being proposed and researched worldwide. Failed back surgery syndrome (FBSS) is the most common indication for SCS, whereas, the complex regional pain syndrome (CRPS) is the second one. Also, this technique is useful in patients with refractory angina and critical limb ischemia, in whom surgical or endovascular treatment cannot be performed. Further indications may be phantom limb pain, chronic intractable pain located in the head, face, neck, or upper extremities, spinal lumbar stenosis in patients who are not surgical candidates, and others. Conclusion: Spinal cord stimulation is a useful tool for neuromodulation, if an accurate patient selection is carried out prior, which should include a trial period. Undoubtedly, this proper selection and a better knowledge of its underlying mechanisms of action, will allow this cutting edge technique to be more acceptable among pain physicians.

Yampolsky, Claudio; Hem, Santiago; Bendersky, Damian

2012-01-01

243

A simple method for the assay of colistin in human plasma, using pre-column derivatization with 9-fluorenylmethyl chloroformate in solid-phase extraction cartridges and reversed-phase high-performance liquid chromatography  

Microsoft Academic Search

A simple, selective and sensitive high-performance liquid chromatographic (HPLC) method is described for the determination of colistin in human plasma. Derivatization with 9-fluorenylmethyl chloroformate was performed in the same solid-phase extraction C18 cartridge used for sample pre-treatment, followed by reversed-phase HPLC with fluorimetric detection. Quantification was achieved using the ratio of the summed peak areas of colistin A and B

Jian Li; Robert W Milne; Roger L Nation; John D Turnidge; Kingsley Coulthard; David W Johnson

2001-01-01

244

Column: Materials Science and Engineering  

Microsoft Academic Search

We gave an overview of material types in the introductory column. In this column, we briefly describe the past, present, and future of materials. Technology makes our lives easier. Its growth during the past 100 years is phenomenal. There is no doubt about the superiority of American agricultural technology. This has resulted in its acceptance worldwide with varying degrees of

Rumana Akmal; Naim Akmal; Arthur Usmani

2004-01-01

245

Selected Topics in Column Generation  

Microsoft Academic Search

Abstract Dantzig-Wolfe decomposition and column generation, devised for linear programs, is a success story in large scale integer programming. We outline and relate the approaches, and survey mainly recent contributions, not found in textbooks, yet. We emphasize on the growing understanding of the dual point of view, which brought considerable progress to the column generation theory and practice. It stimulated

Marco E. Lübbecke; Jacques Desrosiers

2005-01-01

246

Alumina Column Rb-82 Generator.  

National Technical Information Service (NTIS)

The use of an alumina column for the adsorption of radioactive Sr for the generator production of 75-sec exp 82 Rb was evaluated in both batches and column experiments using exp 85 Sr and cyclotron-produced exp 82 Sr. Comparisons of alumina, Bio-Rex 70 an...

Y. Yano E. P. Roth

1977-01-01

247

Evolution of volcanic eruption columns  

NASA Astrophysics Data System (ADS)

The classical steady state model for Plinian eruption columns is extended to allow the source conditions at the volcanic vent to change in time. It is shown that when the source conditions change rapidly, over time scales typically less than approximately 3-4 min, this new time-dependent volcano model becomes appropriate. Differences between changes in source velocity and source temperature are also considered. Qualitatively similar structures are formed when either the source velocity or source temperature is reduced. A transient region is formed, characterized by a narrowing of the “top hat” eruption column radius. A first attempt to a model a Plinian eruption column, from its dynamic initiation in a volcanic eruption, is made. It is shown that the velocity at the front of the eruption column is significantly slower than the velocity at the same height in an established eruption column.

Scase, M. M.

2009-10-01

248

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 1.0-109.0pmolL(-1) and 0.109nmolL(-1)-0.11µmolL(-1) of buprenorphine and the detection limit was found to be as low as 0.6pmolL(-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

2013-08-19

249

Measuring Ultrashort Optical Pulses  

NASA Astrophysics Data System (ADS)

Ultrafast optics has changed dramatically in the last twenty years, driven by new laser sources, as well as new methods of manipulation and measurement for broadband coherent optical fields. In this article we address the means and technologies that enable experimental characterisation of short electromagnetic pulses, indicating the general principles involved, how these have been implemented in various approaches, and how the most popular methods encode the temporal electric field of a short optical pulse in the measured signal and extract the field reliably from the data. We provide a more detailed design for one of the popular methods, SPIDER.

Wyatt, Adam S.; Walmsley, Ian A.

250

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

2006-07-14

251

Optimal design of thermally coupled distillation columns  

Microsoft Academic Search

This paper considers the optimal design of thermally coupled distillation columns and dividing wall columns using detailed column models and mathematical optimization. The column model used is capable of describing both conventional and thermally coupled columns, which allows comparisons of different structural alternatives to be made. Possible savings in both operating and capital costs of up to 30% are illustrated

G. Duennebier; Constantinos C. Pantelides

1999-01-01

252

Measurement and optimization of isolated attosecond pulse contrast.  

PubMed

An experimental method is presented to experimentally measure and control the carrier-envelope-phase (CEP)-dependent pulse-energy contrast of isolated attosecond pulses. By scanning the CEP and measuring the photoelectron spectrum produced by the combined action of the attosecond pulses and the high-harmonic driving laser pulses at zero relative time delay, one can extract the pulse-energy ratio between the main attosecond pulse and its neighboring satellite pulses arriving in preceding or subsequent half-cycles of the driver pulse. Moreover, this method allows fast and efficient in situ retrieval of the optimal CEP for high-contrast isolated attosecond pulse generation. PMID:19529714

Pfeifer, Thomas; Abel, Mark J; Nagel, Phillip M; Boutu, Willem; Bell, M Justine; Liu, Yanwei; Neumark, Daniel M; Leone, Stephen R

2009-06-15

253

Journal Feature Columns: Mission Statements  

NASA Astrophysics Data System (ADS)

An important part of this Journal is its feature columns. Some appear in every issue whereas others appear at much longer intervals, but each provides useful information about a specific aspect of chemical education. Each editor of a feature column has been asked to provide a statement outlining the mission and goals of the column and the types of manuscript that should be submitted. These statements appear below, except for High School features. (Because of the changeover of High School editors, the mission statements for High School features will appear in a subsequent issue.)

1997-01-01

254

Use of specially designed columns for antioxidants and antimicrobials enrichment by preparative supercritical fluid chromatography  

Microsoft Academic Search

A new, specially designed column has been developed for fractionation of supercritical fluid extract of rosemary by using a preparative supercritical fluid chromatography system (Prep-SFC). The column evaluated in this work was prepared using a new packing method consisting of a combination of slurry and supercritical CO2 with commercial silica particles coated with a stationary phase commonly used in gas

Pilar Ramírez; Susana Santoyo; Mónica R. García-Risco; F. Javier Señoráns; Elena Ibáñez; Guillermo Reglero

2007-01-01

255

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

Microsoft Academic Search

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

Ewa M Cukrowska; Koovila Govender; Morris Viljoen

2004-01-01

256

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

257

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 alternation 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 multifunction 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 multifunction ion exchange process is the self-regeneration of the resins. Applications are to separation of nitrogen and sulfur isotopes.

Park, Woo K.

1994-12-31

258

Mud pulse logging while drilling telemetry system: design, development, and demonstrations  

Microsoft Academic Search

Mud pulse telemetry is a method of transmitting information from the vicinity of the drill bit to the surface drilling platform while drilling. Information can be conveyed through a flowing column of drilling mud by the presence or absence of pressure pulses arranged in a binary code. Pressure in the flowing mud column is periodically modulated at a point downhole

R. F. Spinnler; F. A. Stone

1978-01-01

259

Characterization of low-molecular-weight metal species in plant extracts by using HPLC with pulsed amperometric detection and cyclic voltammetry  

Microsoft Academic Search

An analytical separation scheme is presented for the isolation of low-molecular-weight metal species (< 10 kDa) in plants.\\u000a After ultrafiltration of the aqueous plant extracts isotachophoresis or gel chromatography is used for pre-separation and\\u000a HPLC at a cyclodextrin-phase for further separation of metal containing fractions. Trace metals are detected off-line by using\\u000a either adsorptive stripping voltammetry for platinum or AAS

G. Weber; F. Alt; J. Messerschmidt

1998-01-01

260

Automatic Control of Flotation Columns  

Microsoft Academic Search

\\u000a Since their first commercial application for mineral separation in the early 1980s, flotation columns have become a standard\\u000a piece of equipment in mineral concentrators particularly for cleaning operations. This chapter presents and discusses the\\u000a most recent advances in instrumentation and automatic control of flotation columns. It also examines how current industrial\\u000a practice could benefit from recent academic developments in these

René del Villar; André Desbiens; Miguel Maldonado; Jocelyn Bouchard

261

Microbial activity in weathering columns  

Microsoft Academic Search

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).

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

2007-01-01

262

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...

263

FUSED SILICA CAPILLARY COLUMN GC/MS FOR THE ANALYSIS OF PRIORITY POLLUTANTS  

EPA Science Inventory

Operational characteristics have been determined for fused silica capillary column (FSCC) GC/MS as applied to 'extractable' priority pollutants. Chromatographic data show excellent relative retention time (RRT) intralaboratory precision and interlaboratory accuracy when multiple ...

264

Generation of an electric signal in the interaction of HF-laser radiation with bottom surface of a water column  

Microsoft Academic Search

Generation of an electrical signal (ES) is experimentally investigated in the interaction of the pulse of a non-chain electric-discharge HF laser with the bottom surface of a water column. It was found that the ES amplitude is influenced by thin water layers (water contacts) present in the system under study, which undergo mechanical action in the process of water column

Stepan N Andreev; S Yu Kazantsev; I G Kononov; Pavel P Pashinin; K N Firsov

2010-01-01

265

Parallel segmented flow chromatography columns: conventional analytical scale column formats presenting as a 'virtual' narrow bore column.  

PubMed

Narrow bore columns find advantage in HPLC applications when volumetric flow is important, For example, for detection processes that are volume limited. Yet there are significant drawbacks to narrow bore columns. Due to their small column volume relative to analytical scale columns, narrow bore columns are more affected by system dead volume. In addition the wall effect and the variation in packing density from the centre to the wall are more significant in these columns relative to larger scale analytical columns. In this study we operate a 4.6mm i.d. parallel segmented flow column in such a manner that it emulates 2.1mm i.d. and 3.0mm i.d. columns. By using a parallel segmented flow column in this way, it was possible to combine the benefits of narrow bore and analytical scale columns. PMID:22999201

Shalliker, R A; Camenzuli, M; Pereira, L; Ritchie, H J

2012-09-07

266

Monolithic silica liquid chromatography columns for the determination of cyclooxygenase II inhibitors in human plasma  

Microsoft Academic Search

Methods employing monolithic HPLC columns for the determination of the cyclooxygenase II inhibitors rofecoxib (I) and 3-isopropoxy-4-(4-methanesulfonylphenyl)-5,5?-dimethyl-5H-furan-2-one (DFP, III) in human plasma are described. Each analyte, together with an internal standard was extracted from the plasma matrix using solid-phase extraction in the 96-well format. The analytes were chromatographed on a Chromolith Speed Rod monolithic HPLC column (4.6×50 mm). Analyte detection

P. T Vallano; R. S Mazenko; E. J Woolf; B. K Matuszewski

2002-01-01

267

Adiabatic pulses  

Microsoft Academic Search

Adiabatic pulses are sometimes considered to be mysterious and exotic entities which are difficult to understand, complex to generate and impractical to implement. This work is an attempt to bring familiarity and to fulfill the preliminary needs of anyone interested in learning more about this subject. The response of magnetization to stimuli produced by adiabatic pulses is analyzed using vector

Alberto Tannús; Michael Garwood

1997-01-01

268

PULSE AMPLIFIER  

DOEpatents

The improvement of pulse amplifiers used with scintillation detectors is described. The pulse amplifier circuit has the advantage of reducing the harmful effects of overloading cause by large signal inputs. In general the pulse amplifier circuit comprises two amplifier tubes with the input pulses applied to one amplifier grid and coupled to the second amplifier tube through a common cathode load. The output of the second amplifier is coupled from the plate circuit to a cathode follower tube grid and a diode tube in connected from grid to cathode of the cathode follower tube. Degenerative feedback is provided in the second amplifier by coupling a signal from the cathode follower cathode to the second amplifier grid. The circuit proqides moderate gain stability, and overload protection for subsequent pulse circuits.

Johnstone, C.W.

1958-06-17

269

40 YEARS OF EXPERIENCE WITH LIQUID-LIQUID EXTRACTION EQUIPMENT IN THE NUCLEAR INDUSTRY  

SciTech Connect

Three types of liquid-liquid extraction equipment are used in industrial reprocessing plants. Each is described below, with a special focus on pulsed columns and centrifugal extractors, which have been the subject of an extensive R&D program by the French Atomic Energy Commission (CEA). Various models have been developed to simulate equipment behavior and flowsheets. The excellent results obtained during industrial operation of the UP3 and UP2-800 plants in La Hague have confirmed the validity of the choices made during the design phases and pave the way for future improvement of the reprocessing process, from a technical and a financial standpoint.

Drain, F.; Vinoche, R.; Duhamet, J.

2003-02-27

270

CO2-laser–produced plasma columns in a solenoidal magnetic field  

Microsoft Academic Search

A 1-GW CO2 laser pulse has been used to produce extended column breakdown of hydrogen at low pressure in a 20-cm-long solenoid. Magnetic fields of up to 110 kG were used to inhibit radial losses of the plasma column. A differential pumping scheme was devised to prevent formation of an opaque absorption wave travelling out of the solenoid back toward

A. A. Offenberger; M. R. Cervenan; P. R. Smy

1976-01-01

271

CO2-laser-produced plasma columns in a solenoidal magnetic field  

Microsoft Academic Search

A 1-GW CO2 laser pulse has been used to produce extended column breakdown of hydrogen at low pressure in a 20-cm long solenoid. Magnetic fields of up to 110 kG were used to inhibit radial losses of the plasma column. A differential pumping scheme was devised to prevent formation of an opaque absorption wave traveling out of the solenoid back

A. A. Offenberger; M. R. Cervenan; P. R. Smy

1976-01-01

272

Seismic performance of hybrid fiber reinforced polymer-concrete pier columns  

Microsoft Academic Search

As part of a multi-university research program funded by NSF, a comprehensive experimental and analytical study of seismic behavior of hybrid fiber reinforced polymer (FRP)-concrete column is presented in this dissertation. Experimental investigation includes cyclic tests of six large-scale concrete-filled FRP tube (CFFT) and RC columns followed by monotonic flexural tests, a nondestructive evaluation of damage using ultrasonic pulse velocity

Yilei Shi

2009-01-01

273

Seismic Performance of Hybrid Fiber Reinforced Polymer-Concrete Pier Columns  

Microsoft Academic Search

As part of a multi-university research program funded by NSF, a comprehensive experimental and analytical study of seismic behavior of hybrid fiber reinforced polymer (FRP)-concrete column is presented in this dissertation. Experimental investigation includes cyclic tests of six large-scale concrete-filled FRP tube (CFFT) and RC columns followed by monotonic flexural tests, a nondestructive evaluation of damage using ultrasonic pulse velocity

Yilei Shi

2009-01-01

274

Multispecies transport of metal–EDTA complexes and chromate through undisturbed columns of weathered fractured saprolite  

Microsoft Academic Search

Laboratory-scale tracer experiments were conducted to investigate the geochemical and hydrological processes that govern the fate and transport of organically chelated radionuclides and toxic metals in undisturbed saturated columns of weathered, fractured shale saprolite. Three long-term, reactive contaminant injections were pulsed onto three separate soil columns, with the following influent mixtures: (1) 109CdEDTA2?, (2) 109CdEDTA2? and 57,58Co(II)EDTA2?, and (3) 109CdEDTA2?,

M. A Mayes; P. M Jardine; I. L Larsen; S. C Brooks; S. E Fendorf

2000-01-01

275

Avoid problems during distillation column startups  

Microsoft Academic Search

The startup of a distillation column is the end product of the design process. Indeed, startup is the culmination of the theory and practice of designing the column to meet the process objectives. The author will direct most of this discussion towards column revamps due to their inherent complexity; however, the points apply equally to new columns, as well. The

Sloley

1996-01-01

276

Dissolution profiles in column dissolution.  

PubMed

A self-consistent model for open-ended column dissolution is presented. It is shown that when the concentration of the efflux stream from the column is plotted versus time, then the profile is fairly level at first and then drops rapidly, in the form of an inverse sigmoid profile. The model assumes that the particles are isometric and that they adhere to a Levich type particulate dissolution, and it is based on plug flow with a given residence time. Consistency is shown between the plug flow parameter (Q2) and experimental data. Good correlation is found between predicted and experimental profiles. PMID:3772748

Carstensen, J T; Yonezawa, Y

1986-08-01

277

Reirradiation of Spinal Column Metastases  

Microsoft Academic Search

\\u000a \\u000a Background:\\u000a   For reirradiation of spinal column metastases, intensity-modulated radiation therapy (IMRT) reduces the dose to the spinal\\u000a cord, while allowing longer treatment times. We analyzed the potential of volumetric modulated arc therapy (VMAT) to reduce\\u000a treatment time and number of monitor units (MU).\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a Patients and Methods:\\u000a   In CT datasets of 9 patients with spinal column metastases, the planned target volume

Florian Stieler; Dirk Wolff; Linda Bauer; Hans-Jörg Wertz; Frederik Wenz; Frank Lohr

2011-01-01

278

Application of immunoaffinity columns to mycotoxin analysis.  

PubMed

Immunoaffinity columns (IACs) are widely used for cleanup and isolation of mycotoxins extracted from foods and biological fluids, particularly aflatoxins, ochratoxin A, and fumonisins. The columns are prepared by binding antibodies specific for a given mycotoxin to a specially activated solid-phase support and packing the support suspended in aqueous buffer solution into a cartridge. The mycotoxin in the extract or fluid binds to the antibody, impurities are removed with water or aqueous solution, and then the mycotoxin is desorbed with a miscible solvent such as methanol. Further separation can be performed with IAC, followed by liquid chromatographic (LC) quantitation, either off-line or on-line in an automated system, or by fluorometry. IACs have been used by laboratories that developed the antibodies but are also available commercially for aflatoxins, ochratoxin A, fumonisins, zearalenone, and deoxynivalenol. Among commercial IACs, Aflatest P is used as the cleanup step in an LC method and in a solution fluorometry method for corn, peanuts, and peanut butter that was adopted as an AOAC INTERNATIONAL Official Method after evaluation by an international collaborative study. As part of a fluorometer-based test kit, aflatest P was further certified by the AOAC Research Institute to measure total aflatoxins in 10 grains and grain products. IACs can concentrate the analyte from a large amount of sample, allowing detection limits at low parts-per-trillion levels in some cases (e.g., for aflatoxin M1 and ochratoxin A in liquid food matrixes). Regeneration of IACs for reuse in aflatoxin, ochratoxin A, fumonisin, and zearalenone analyses has been investigated. PMID:9325571

Scott, P M; Trucksess, M W

279

Fabrication of high-quality microfluidic solid-phase chromatography columns.  

PubMed

Here we report a low-pressure bead packing technique for the robust integration of high-performance chromatography columns in poly(dimethylsiloxane) microfluidic devices made by multilayer soft lithography (MSL). A novel column geometry featuring micrometer-sized bypass channels along the entire length of the separation channel is used to achieve rapid packing of multiple high-quality bead bed columns in parallel with near-perfect yield. Pulse tests show that these microfluidic columns achieve exceptional reproducibility and efficiency, with measured plate counts of 1,650,000/m ± 7%, corresponding to a reduced plate height of h = 0.12 ± 7%. The combination of high-performance chromatography columns and valve-based microfluidics offers new opportunities for the integration of sample processing with preparative and analytical separations for biology and chemistry. PMID:23234506

Huft, Jens; Haynes, Charles A; Hansen, Carl L

2013-01-10

280

Editorial: Research and Teaching Column  

NSDL National Science Digital Library

The JCST Research and Teaching column will feature sound research on curriculum, pedagogy, and student learning at the college level. Topics of interest include all fields of science: chemistry, biology, geology, astronomy, physics, geography, mathematics, environmental science, and computer science. Studies that are interdisciplinary or are readily applicable to several disciplines in the sciences are also of interest.

Towns, Marcy

2008-03-01

281

Streamlined, two-column, simulated countercurrent chromatography for binary separation.  

PubMed

We report on a numerical and experimental study of two-column versions of streamlined, multicolumn, semi-continuous chromatography for binary separation. The systems combine a flexible node design, cyclic flow-rate modulation, and relayed operation of the inlet/outlet ports to extend the mass-transfer zone over the largest possible length, while keeping it inside the system at all times. One advantage of these streamlined designs is the simplicity of their physical realization: regardless of the number of columns, they only require two pumps to supply feed and desorbent into the system, while the flow rates of liquid withdrawn from the system are controlled by material balance using simple two-way valves. In one case, an extra pump is needed to recirculate the fluid in closed-loop. A rigorous model-based optimization approach is employed in the optimal design of the cycles to generate solutions that are physically realizable in the experimental set-ups. The optimized schemes for two-column operation supply fresh feed into the middle of the system where the composition of the circulating fluid is closest to that of the feedstock fluid, and recover the purified products, extract and raffinate, alternately at the downstream end of the unit, while desorbent is continuously supplied into the upstream end of the system. By internally recycling part of the non-pure cut fraction, the scheme with a step of closed-loop recycling significantly reduces its solvent consumption. The feasibility and effectiveness of the reported two-column processes have been verified experimentally on the linear separation of nucleosides by reversed phase subject to 99% purity constraints on both products. It is shown that our processes compare favorably against single-column batch chromatography, steady-state recycling, and four-column, open-loop SMB, for the same amount of adsorbent; they are also better than the four-column, closed-loop SMB at high feed throughputs. PMID:20356598

Rodrigues, Rui C R; Silva, Ricardo J S; Mota, José P B

2010-03-16

282

[Poetry Instruction.] Motivator of the Month. [Compiled from Columns in Three issues of "Notes Plus," January and November 1984 and September 1985.  

ERIC Educational Resources Information Center

|The teaching activities presented in the four journal columns extracted here focus on understanding and writing poetry. The first column (by Carol Case) presents an introduction to poetry unit containing five preliminary steps designed to help students develop an understanding of poetry. The second column (by Carol Anderson) describes a week of…

Notes Plus, 1985

1985-01-01

283

Isolation of tomato pectin methylesterase and polygalacturonase on monolithic columns  

Microsoft Academic Search

An improved cation-exchange chromatographic procedure on Convective Interaction Media (CIM, BIA Separations, Ljubljana, Slovenia) short monolithic methacrylate disk columns was used for the isolation of salt-independent pectin methylesterase (PME; EC 3.1.1.11) isoform and endo-polygalacturonase PG1 (PG, EC 3.2.1.15) from ripe tomato fruit extract after studying the chromatographic conditions including type of disk, binding buffer, pH, eluent composition and different gradients.

Irena Vovk; Breda Simonovska

2007-01-01

284

Revised Thermal Analysis of LANL Ion Exchange Column  

SciTech Connect

This document updates a previous calculation of the temperature distributions in a Los Alamos National Laboratory (LANL) ion exchange column.1 LANL operates two laboratory-scale anion exchange columns, in series, to extract Pu-238 from nitric acid solutions. The Defense Nuclear Facilities Safety Board has requested an updated analysis to calculate maximum temperatures for higher resin loading capacities obtained with a new formulation of the Reillex HPQ anion exchange resin. The increased resin loading capacity will not exceed 118 g plutonium per L of resin bed. Calculations were requested for normal operation of the resin bed at the minimum allowable solution feed rate of 30 mL/min and after an interruption of flow at the end of the feed stage, when one of the columns is fully loaded. 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. At low temperatures, resin bed temperatures increase primarily due to decay heat. At {approx}70 C a Low Temperature Exotherm (LTE) resulting from the reaction between 8-12 M HNO{sub 3} and the resin has been observed. The LTE has been attributed to an irreversible oxidation of pendant ethyl benzene groups at the termini of the resin polymer chains by nitric acid. The ethyl benzene groups are converted to benzoic acid moities. The resin can be treated to permanently remove the LTE by heating a resin suspension in 8M HNO{sub 3} for 30-45 minutes. No degradation of the resin performance is observed after the LTE removal treatment. In fact, heating the resin in boiling ({approx}115-120 C) 12 M HNO{sub 3} for 3 hr displays thermal stability analogous to resin that has been treated to remove the LTE. The analysis is based on a previous study of the SRS Frames Waste Recovery (FWR) column, performed in support of the Pu-238 production campaign for NASA's Cassini mission. In that study, temperature transients following an interruption of flow to the column were calculated. The transient calculations were terminated after the maximum resin bed temperature reached the Technical Standard of 60 C, which was set to prevent significant resin degradation. The LANL column differs from the FWR column in that it has a significantly smaller radius, 3.73 cm nominal versus approximately 28 cm. It follows that natural convection removes heat much more effectively from the LANL column, so that the column may reach thermal equilibrium. Consequently, the calculations for a flow interruption were extended until an approach to thermal equilibrium was observed. The LANL ion exchange process also uses a different resin than was used in the FWR column. The LANL column uses Reillex HPQ{trademark} resin, which is more resistant to attack by nitric acid than the Ionac 641{trademark} resin used in the FWR column. Heat generation from the resin oxidation reaction with nitric acid is neglected in this analysis since LANL will be treating the resin to remove the LTE prior to loading the resin in the columns. Calculations were performed using a finite difference computer code, which incorporates models for absorption and elution of plutonium and for forced and natural convection within the resin bed. Calculations for normal column operation during loading were performed using an initial temperature and a feed temperature equal to the ambient air temperature. The model for the normal flow calculations did not include natural convection within the resin bed. The no flow calculations were started with the temperature and concentration profiles at the end of the loading stage, when there would be a maximum amount of plutonium either adsorbed on the resin or in the feed solution in the column.

Laurinat, J

2006-04-11

285

Ceramic column grid array technology with coated solder columns  

Microsoft Academic Search

Flip-chip carriers are finding increasing use for high-performance ASIC and microprocessors chips. Many of these chips have a large I\\/O count and consequently drive chip carriers with high density second-level interconnection requirements (typically 400 to more than 1000). IBM has a range of Ceramic Ball Grid Array (CBGA) and Ceramic Column Grid Array (CCGA) offerings which cover this application range.

Bor Zen Hong; Sudipta K. Ray

2000-01-01

286

HYDROPHILIC INTERACTION CHROMATOGRAPHIC DETERMINATION OF OXYTETRACYCLINE IN THE ENVIRONMENTAL WATER USING SILICA COLUMN  

Microsoft Academic Search

In the present study, a simple, sensitive, and rapid hydrophilic interaction chromatographic (HILIC) method with ultraviolet (UV) detection for the analysis of oxytetracycline (OTC) was developed and applied to the determination of the antibiotic in environmental waters. OTC was extracted and purified from water samples by solid-phase extraction (SPE) employing Oasis HLB cartridge and analyzed on a Kromasil silica column

Ruiping Li; Qin Yuan; Yi Zhang; Jing Ling; Tiantian Han

2011-01-01

287

Adaptive pulse compression via MMSE estimation  

Microsoft Academic Search

Radar pulse compression involves the extraction of an estimate of the range profile illuminated by a radar in the presence of noise. A problem inherent to pulse compression is the masking of small targets by large nearby targets due to the range sidelobes that result from standard matched filtering. This paper presents a new approach based upon a minimum mean-square

SHANNON D. BLUNT; KARL GERLACH

2006-01-01

288

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

2012-08-05

289

Profiling of impurities in illicit amphetamine samples by high-performance liquid chromatography using column switching.  

PubMed

A simple high-performance liquid chromatographic method, suitable for routine profiling of impurities in illegally produced amphetamine, has been developed. Amphetamine is dissolved in acetonitrile-citrate buffer (pH 3) (2:8) and injected directly without further sample pre-treatment. The impurities are enriched on-line on a C8 extraction column, while amphetamine and polar diluents are washed out with water. After washing for 1.5 min, a six-port valve is switched and an acetonitrile-0.2 M butylamine in water (pH 8) gradient elutes the impurities from the extraction column on to a C18 analytical column where they are separated. The compounds are monitored by UV detection at 220 and 254 nm. The total extraction and analysis time is 30 min. The method allows automated extraction and analysis to be performed. PMID:3805205

Lambrechts, M; Tönnesen, F; Rasmussen, K E

1986-11-21

290

Beam Studies with Electron Columns  

SciTech Connect

We report preliminary results of experimental studies of 'electron columns' in the Tevatron and in a specialized test setup. In the Tevatron, a beam of 150 GeV protons ionizes residual gas and ionization electrons are stored in an electrostatic trap immersed into strong longitudinal magnetic field. Shifts of proton betatron frequencies are observed. In the test setup, we observe effects pointing to accumulation and escape of ionization electrons.

Shiltsev, V.; Valishev, A.; Kuznetsov, G.; /Fermilab; Kamerdzhiev, V.; /Julich, Forschungszentrum; Romanov, A.; /Novosibirsk, IYF

2009-04-01

291

PSR extraction kicker system improvements  

Microsoft Academic Search

A program to improve the reliability of the hardware required to operate the Los Alamos Proton Storage Ring (PSR) is under way. The extraction kicker system for the PSR was identified as one candidate for improvement. Pulse modulators produce 50-kV pulses 360 ns in length at up to a 24-Hz pulse repetition rate and drive two 4-m-long stripline electrodes. Sources

T. W. Hardek

1991-01-01

292

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

293

Novel electrostatic column for ion projection lithography  

SciTech Connect

Ion projection lithography (IPL) is being considered for high volume sub-0.25-[mu]m lithography. A novel ion-optical column has been designed for exposing 20[times]20 mm[sup 2] fields at 3[times] reduction from stencil mask to wafer substrates. A diverging lens is realized by using the stencil mask as the first electrode of the ion-optical column. The second and third electrode form an accelerating field lens. The aberrations of the first two lenses (diverging lens and field lens) are compensated by an asymmetric Einzel lens projecting an ion image of the stencil mask openings onto the wafer substrate with better than 2 mrad telecentricity. Less than 30 nm intrafield distortion was calculated within 20[times]20 mm[sup 2] exposure fields. The calculation uncertainty is estimated to be about 10 nm. The calculation holds for helium ions with [approx]10 keV ion energy at the stencil mask and 150 keV ion energy at the wafer plane. A virtual ion source size of 10 [mu]m has been assumed. The calculated chromatic aberrations are less than 60 nm, assuming 6 eV energy spread of the ions extracted from a duoplasmatron source. Recently a multicusp ion source has been developed for which preliminary results indicate an energy spread of less than 2 eV. Thus, with a multicusp source chromatic aberrations of less than 20 nm are to be expected. The ion energy at the crossover between the field lens and the asymmetric Einzel lens is 200 keV. Therefore, stochastic space charge induced degradations in resolution can be kept sufficiently low. The divergence of the ion image projected to the wafer plane is less than 2 mrad. Thus, the usable'' depth of focus for the novel ion optics is in the order of 10 [mu]m.

Chalupka, A.; Stengl, G.; Buschbeck, H.; Lammer, G.; Vonach, H.; Fischer, R.; Hammel, E.; Loeschner, H.; Nowak, R.; Wolf, P. (IMS - Ion Microfabrication Systems GmbH, A-1020 Vienna (Austria)); Finkelstein, W.; Hill, R.W. (Advanced Lithography Group, Columbia, Maryland 21045 (United States)); Berry, I.L. (Department of Defense, Microelectronics Research Laboratory, Columbia, Maryland 21045 (United States)); Harriott, L.R. (AT T Bell Laboratories, Murray Hill, New Jersey 07974 (United States)); Melngailis, J. (University of Maryland, College Park, Maryland 20742 (United States)); Randall, J.N. (Texas Instruments, Dallas, Texas 75243 (United States)); Wolfe, J.C. (University of Houston, Houston, Texas 77204 (United States)); Stroh, H.; Wollnik, H. (University of Giessen, D-35392 Giessen (Germany)); Mondelli, A.A.; Petillo, J.J. (Science Applications International Corporation, McLean, Virginia 22102 (United States)); Leung, K. (Lawrence Berkeley Laboratory, University of Californi

1994-11-01

294

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

PubMed Central

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 signal and its usefulness for assessing pulse rate variability (PRV). Methods Simulated pulse wave signals with known pulse interval functions and actual pulse wave signals obtained from 30 subjects with a trans-dermal pulse wave device were analyzed by PFDM. The results were compared with heart rate and HRV assessed from simultaneously recorded ECG. Results Analysis of simulated data revealed that the PFDM faithfully demodulates source interval function with preserving the frequency characteristics of the function, even when the intervals fluctuate rapidly over a wide range and when the signals include fluctuations in pulse height and baseline. Analysis of actual data revealed that individual means of low and high frequency components of PRV showed good agreement with those of HRV (intraclass correlation coefficient, 0.997 and 0.981, respectively). Conclusion The PFDM of pulse wave signal provides a reliable assessment of PRV. Given the popularity of pulse wave equipments, PFDM may open new ways to the studies of long-term assessment of cardiovascular variability and dynamics.

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

2005-01-01

295

Tests of high strength steel columns  

Microsoft Academic Search

The paper describes a test programme on columns fabricated from high strength steel plates with nominal yield stress of 690 MPa. The programme comprised 13 box and I-section specimens, including fixed-ended stub columns and pin-ended long columns. For the pin-ended columns, two tests were performed for each length using eccentric and concentric axial loading. The purpose of the test programme

K. J. R. Rasmussen; G. J. Hancock

1995-01-01

296

Preparation of polar glass capillary columns  

Microsoft Academic Search

The use of ether as the solvent for the stationary phase in the preparation of wall-coated capillary columns significantly reduced the time required for column preparation. Evaporation proceeded rapidly and smoothly, with no internal disruption of the liquid column as long as the bath temperature was sufficiently subambient. At 19°C, columns over 60 m in length were coated in only

Cecil E. Higgins

1981-01-01

297

SIGACT news complexity theory column 34  

Microsoft Academic Search

This issue's guest columnists are angels. The column was faced with a last-minute cancellation, and they prepared on very short notice a wonderful column. And I'm sure that many readers of the column will want to learn even more by, for example, reading their monograph Complexity Classifications of Boolean Constraint Satisfaction Problems [7].Future complexity columns include Holzer\\/McKenzie on a familiar

2001-01-01

298

Column-Generation in Integer Linear Programming  

Microsoft Academic Search

We present an exact method for integer linear program- ming problems that combines branch and bound with column genera- tion at each node of the search tree. For the case of models involving binary column vectors only, we propose the use of so-called geometrical cuts to be added to the subproblem in order to eliminate previously generated columns. This scheme

Nelson Maculan; Irene Loiseau

2003-01-01

299

CIRCULATION IN LARGE SCALE JET BUBBLE COLUMNS  

Microsoft Academic Search

A hydrodynamic study in a gas-liquid jet bubble column was undertaken in a column with a 122 cm diameter cylindrical section and a conical bottom section approximately 180cm in height. Due to the jetting action in the cone, the circulation patterns are different from those in cylindrical bubble columns. In order to examine this difference in flow pattern, circulation velocity

Y. T. SHAH; N. YANG; S. D. GHARAT; K. WISECARVER; B. SOLARI

1991-01-01

300

Elastoplastic Confinement Model for Circular Concrete Columns  

Microsoft Academic Search

This paper presents relatively simple, analytically derived curves to model the axial and the lateral stress-strain relations of circular concrete columns. The analytical curves describe the full elastoplastic behavior of the confined concrete column. The solution to the partially confined reinforced concrete column in the elastoplastic range is derived by replacing the discrete lateral reinforcement with an equivalent tube and

R. Eid; A. N. Dancygier

2007-01-01

301

Strength of welded jumbo box columns  

Microsoft Academic Search

The ultimate strength of hot?rolled wide flange steel columns has been studied extensively. However, very limited research work has been carried out on welded box columns, especially the jumbo type. This study focuses on the ultimate strength of welded jumbo box columns which are fabricated from four steel plates. The magnitude and distribution of residual stresses due to welding processes

1992-01-01

302

Fracture of long and short notched columns  

Microsoft Academic Search

Studies were conducted on machined-notched and fatigue-cracked columns of various lengths subjected simultaneously to axial compression and bending. Different failure criteria were examined for columns under such loading. Three methods are used to analyze the failure data. Results obtained for the aluminum columns investigated indicate that the energy required to initiate crack propagation may be stated approximately as an exponential

H. Liebowitz; D. W. Harris; H. Vanderveldt

1968-01-01

303

Study on a Continuous Heat Integrated Distillation Column  

Microsoft Academic Search

A novel continuous heat integrated distillation column called a concentric column has been studied using computer simulation. It is shown that a concentric column is a novel implementation of a thermodynamically reversible distillation column and has a lower energy loss than an ordinary distillation column. Our studies show that a concentric column has reduced column height, since the stripping section

Thomas Glenchur; Rakesh Govind

1987-01-01

304

The Amsterdam pulse stretcher  

SciTech Connect

In order to increase the duty factor (d.f.) of the present 500 MeV electron linac from 2.5 % to > 90 %, it is proposed to add a pulse stretcher to the facility. By replacing 4 of the 12 existing 4 MW klystrons by 25 MW types, the injection energy will be increased to E = 700 MeV. A peak current of 40 mA will be injected during three turns with 365 pps. to yield an extracted beam current of 40 ..mu..A. The machine operates near a third order resonance. The chromaticity is non-zero. Extraction proceeds by changing the cavity frequency (2856 MHz); this will push the beam into the unstable region of the phase space. An energy compressor will reduce the momentum spread of the injected beam to exclamationdp/pexclamation = 0.1 %.

Maas, R.; deVries, C.; Burinsma, P.T.J.; Kroes, F.B.; Luijekx, G.; Noomen, J.G.; Vogel, A.G.C.

1985-10-01

305

The role of water on the equilibrium of esterification by immobilized lipase packed-bed column reactor  

Microsoft Academic Search

Summary The role of water on the continous synthesis of geranyl esters by immobilized lipase fromHumicola lanuginosa No. 3 was studied in a packed-bed column reactor (PBR) installed with a molecular sieve column for water extraction. The conversion degress by PBR were highly influenced by the water concentration throughout the reaction which acted as a determinant on the reaction equilibrium.

Ibrahim Che Omar; Naomichi Nishio; Shiro Nagai

1988-01-01

306

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

307

Haze Formation and Behavior in Liquid-Liquid Extraction Processes  

SciTech Connect

Aqueous haze formation and behavior was studied in the liquid-liquid system tri-n-butyl phosphate in odorless kerosene and 3M nitric acid with uranyl nitrate and cesium nitrate representing the major solute and an impurity, respectively. A pulsed column, mixer-settler and centrifugal contactor were chosen to investigate the effect of different turbulence characteristics on the manifestation of haze since these contactors exhibit distinct mixing phenomena. The dispersive processes of drop coalescence and breakage, and water precipitation in the organic phase were observed to lead to the formation of haze drops of {approx}1 um in diameter. The interaction between the haze and primary drops of the dispersion was critical to the separation efficiency of the liquid-liquid extraction equipment. Conditions of high power input and spatially homogeneous mixing enabled the haze drops to become rapidly assimilated within the dispersion to maximize the scrub performance and separation efficiency of the equipment.

Arm, Stuart T.; Jenkins, J. A.

2006-07-31

308

A source with ion extraction from the plasma volume  

NASA Astrophysics Data System (ADS)

The physical basis of an effective new variant of ion source with extraction of ions from the plasma volume, operating in a longitudinal magnetic field developed at the Kurchatov Institute, is described. A thin layer with an electric field is produced in the plasma column of the source without violation of plasma quasineutrality, in order to transport all types of charged particles across the magnetic field toward the extraction slit. This allows high plasma flows to be transported toward the extraction slit with low potential difference ?U across the layer, and the ion current density in the extracted ion beam can be increased by up to 10-15 times. The induced plasma flow also increases significantly the content of multicharged ions in the beam. A strong dependence of the ion beam current intensity on the potential across the layer provides a means for pulsed modulating or stabilizing the current intensity at the target by special programming or feedback in an inertia-free manner, without changes in the discharge conditions. The ion source operates with various species-gas or sputter materials. An ion current density of 1.5 A/cm2 was measured in our experiments at ?U=10 V. The source can be used for accelerators, in semiconductor technology, and for other applications.

Makov, B. N.

2000-11-01

309

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...

310

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...

311

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.

312

Conditioning laboratory columns for hysteresis studies  

NASA Astrophysics Data System (ADS)

Evaluating surface area effects on chemical transport properties required estimating the role of hysteresis in the chemical transport processes. To evaluate hysteresis effect unsaturated soil columns at comparable water contents and flow rates were needed. But one column needed to be wetting and a comparable column needed to undergoing drying. Taking advantage of the nearly non-hysteretic behavior in the hydraulic conductivity-water content function, the wetting column was brought to a constant flux rate from a dry condition. The second column was brought to the same flow rate but was started from a wet condition. The apparatus and equilibration times are presented.

Sisson, J. B.; Schaffer, A.

2002-12-01

313

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA Generation of an electric signal in the interaction of HF-laser radiation with bottom surface of a water column  

Microsoft Academic Search

Generation of an electrical signal (ES) is experimentally investigated in the interaction of the pulse of a non-chain electric-discharge HF laser with the bottom surface of a water column. It was found that the ES amplitude is influenced by thin water layers (water contacts) present in the system under study, which undergo mechanical action in the process of water column

Stepan N. Andreev; S. Yu Kazantsev; I. G. Kononov; Pavel P. Pashinin; K. N. Firsov

2010-01-01

314

Pulse waveforms classification based on wavelet network.  

PubMed

This paper proposes a new algorithm to classify pulse waveforms based on discrete wavelet network. This paper selects 4-order discrete Daubechies wavelet as the wavelet node of this wavelet network to classify six pulse patterns distinctive in shape. 600 pulse records are used to train this wavelet network and 300 pulse records are used to test the classifier's performance. The test results show that this approach has 83% agreement rate with the experienced experts. Compared with traditional classification methods, it needs not the experience in feature extraction. PMID:17281263

Xu, L S; Wang, K Q; Wang, L

2005-01-01

315

Fossil methane source dominates Cariaco Basin water column methane geochemistry  

NASA Astrophysics Data System (ADS)

Natural radiocarbon measurements on methane (14C-CH4) extracted from the Cariaco Basin water column show that 98% of the methane in Cariaco Basin waters is derived from fossil (radiocarbon-free) sources. Previous work on Cariaco Basin methane (CH4) considered only a diagenetic sediment source. Similar measurements of sediment 14C-CH4 indicate that sediment CH4 is produced from modern particulate material; thus the sediment and water column CH4 have distinct sources. Using time-dependent CH4 geochemical box models which include a fossil seep CH4 source term, we estimate 1) 0.024-0.028 Tg y-1 of seep CH4 are added to the Cariaco Basin water column, 2) the water column CH4 will reach a steady-state concentration by the year 2065, and 3) the seep CH4 inputs possibly began in 1967, following the July 30 Caracas earthquake. Oxidizing this CH4 to dissolved inorganic carbon does not appear to affect Cariaco Basin 14C chronologies.

Kessler, J. D.; Reeburgh, W. S.; Southon, J.; Varela, R.

2005-06-01

316

Determination of polar organic solutes in methanol using hot on-column injection capillary gas chromatography  

Microsoft Academic Search

In an attempt to improve the analysis of methanolic extracts of atmospheric samples containing highly polar, water-soluble organic compounds using capillary gas chromatography, the hot on-column injection technique was chosen. Since the on-column injector used was not designed to be heated, the point of injection was inside the heated gas chromatograph oven. Preliminary analyses indicated solute peak splitting and distortion

Russell F. Lang

1986-01-01

317

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

318

Propagation of axisymmetric Trivelpiece-Gould mode along vortex columns generated by diocotron instability  

SciTech Connect

A high-frequency (HF) oscillation has been observed to propagate along magnetic field lines with an axisymmetric profile extending over multiple columns of magnetized pure electron plasma which undergo two-dimensional vortex motions. The observed frequency is a few hundred times higher than the rotation frequency of the vortices and varies in time as the density distribution of electrons deforms from an unstable hollow profile into vortex columns and approaches a single-peaked distribution. Experimental examinations reveal that the HF oscillation is excited by the gate pulse applied to prepare the initial profile and that the oscillation does not influence the subsequent dynamics of vortex columns. Further examinations including detailed observations and theoretical analyses indicate that the HF oscillation represents a profile-dependent eigenfunction of the Trivelpiece-Gould mode wave that consists of a dominant axisymmetric component and small fractions of higher azimuthal modes associated with the density distribution separated into columns.

Kawai, Y.; Kiwamoto, Y.; Soga, Y.; Aoki, J. [Graduate School of Human and Environmental Studies, Kyoto University, Yoshidanihonmatsu-cho-Kyoto-shi, Kyoto-fu 606-8501 (Japan)

2007-10-15

319

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

320

Polyamine analysis using N-hydroxysuccinimidyl-6-aminoquinoyl carbamate for pre-column derivatization.  

PubMed

N-Hydroxysuccinimidyl-6-aminoquinoyl carbamate (AccQ.Fluor) was used as a polyamine pre-column derivatization reagent prior to HPLC analysis using a 5-micron C8 reversed-phase column. The fluorescence detector excitation wavelength was set at 250 nm and emission at 395 nm. Quantitation, reproducibility, linearity, recovery and stability were demonstrated. The lower limit of detection was 660 fmol. This method is 45 and 61 times more sensitive than those using the pre-column derivatizing agents dansyl chloride and orthophthalaldehyde, respectively. Applicability to biological samples was demonstrated by analyses of polyamines in extracts of mouse erythrocytes and Trypanosoma brucei brucei. PMID:8852721

Merali, S; Clarkson, A B

1996-01-26

321

Screening and determination of ?-blockers, narcotic analgesics and stimulants in urine by high-performance liquid chromatography with column switching  

Microsoft Academic Search

A fast method is described for the screening of eleven ?-blockers, two narcotic analgesics and two stimulants in urine by HPLC with column switching. The urine sample (100 ?l), buffered tto pH 9–9.5, is injected onto a short extraction column packed with CN stationary phase. The extraction is flushed with water for 2.5 min to elute polar matrix components to

M. T. Saarinen; H. Sirén; M.-L. Riekkola

1995-01-01

322

Use of an immunoaffinity column for tetrachlorodibenzo-p-dioxin serum sample cleanup.  

PubMed

Covalently linking 1-amino-3,7,8-trichlorodibenzo-p-dioxin with either keyhole limpet hemocyanin (KLH) or bovine serum albumin (BSA) provided antigens that generated antibodies in chickens. Competitive ELISA analysis demonstrated that the antibodies isolated from egg yolk (IgY) bound with 1,3,7,8-tetrachlorodibenzo-p-dioxin (1,3,7,8-TCDD). The antibodies were linked to CNBr-Sepharose to generate an immunoaffinity column. Radiolabeled 1,3,7,8-TCDD in a 0.05% Tween 20 solution was retained by the column and could be eluted by increasing the Tween 20 concentration. The binding efficiency for 10.7 ng per ml gel matrix ranged from 85 to 97%. Immunoaffinity columns generated by this method did not effectively bind 14C-1,3,7,8-TCDD from serum samples. Diluting the serum 1:20 with 0.05% Tween 20 increased the binding efficiency. Alternately, ethanol-hexane extraction followed by solid phase extraction on a carbon column using a fat removal protocol also provided an appropriate preaffinity column cleanup for serum samples. After this preaffinity column cleanup, spiked serum samples applied to the immunoaffinity column showed binding efficiencies of over 90%. PMID:9521562

Shelver, W L; Larsen, G L; Huwe, J K

1998-02-13

323

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.

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

2010-01-01

324

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

325

Tevatron extraction microcomputer  

SciTech Connect

Extraction in the Fermilab Tevatron is controlled by a multi-processor Multibus microcomputer system called QXR (Quad eXtraction Regulator). QXR monitors several analog beam signals and controls three sets of power supplies: the ''bucker'' and ''pulse'' magnets at a rate of 5760 Hz, and the ''QXR'' magnets at 720 Hz. QXR supports multiple slow spills (up to a total of 35 seconds) with multiple fast pulses intermixed. It linearizes the slow spill and bucks out the high frequency components. Fast extraction is done by outputting a variable pulse waveform. Closed loop learning techniques are used to improve performance from cycle to cycle for both slow and fast extraction. The system is connected to the Tevatron clock system so that it can track the machine cycle. QXR is also connected to the rest of the Fermilab control system, ACNET. Through ACNET, human operators and central computers can monitor and control extraction through communications with QXR. The controls hardware and software both employ some standard and some specialized components. This paper gives an overview of QXR as a control system; another paper summarizes performance.

Chapman, L.; Finley, D.A.; Harrison, M.; Merz, W.

1985-06-01

326

Tevatron extraction microcomputer  

NASA Astrophysics Data System (ADS)

Extraction in the fErmilab Tevatron is controlled by a multi-processor Multibus microcomputer system called QXR (Quad extraction Regulator). QXR monitors several analog beam signals and controls three sets of power supplies: the bucker and pulse magnets at a rate of 5760 Hz, and the QXR magnets at 720 Hz. QXR supports multiple slow spills (up to a total of 35 seconds) with multiple fast pulses intermixed. It linearizes the slow spill and bucks out the high frequency components. Fast extraction is done by outputting a variable pulse waveform. Closed loop learning techniques are used to improve performance from cycle to cycle for both slow and fast extraction. The system is connected to the Tevatron clock system so that it can track the machine cycle. QXR is also connected to the rest of the Fermilab control system, ACNET. Through ACNET, human operators and central computers can monitor and control extraction through communications with QXR. The controls hardware and software both employ some standard and some specialized components. This paper gives an overview of QXR as a control system; another paper summarizes performance.

Chapman, L.; Finley, D. A.; Harrison, M.; Merz, W.

1985-06-01

327

Cross-column prediction of gas-chromatographic retention of polybrominated diphenyl ethers.  

PubMed

In this paper, we predict the retention of polybrominated diphenyl ethers (PBDEs) in capillary gas-chromatography (GC) within a useful range of separation conditions. In a first stage of this study, quantitative structure-retention relationships (QSRRs) of PBDEs in six stationary phases with different polarity are established. The single-column QSRR models are generated using the retention data of 126 PBDE congeners by multilinear regression (MLR) coupled to genetic algorithm variable selection applied to a large set of theoretical molecular descriptors of different classes. A quite accurate fitting of experimental retentions is obtained for each of the six GC columns adopting five molecular descriptors. In a further step of this work six molecular descriptors were extracted within the set of molecular descriptors (17 variables) involved in the various single-column QSRRs. The selected molecular descriptors are combined with observed retentions of ten representative PBDEs, adopted as descriptors of the GC system. These quantities are considered as the independent variables of a multiple-column retention model able to simultaneously relate GC retention to PBDE molecular structure and kind of column. The quantitative structure/column-retention relationship is established using a multi-layer artificial neural network (ANN) as regression tool. To optimise the ANN model, a validation set is generated by selecting two out of the six calibration columns. Splitting of columns between training and validation sets, as well as selection of PBDE congeners to be used as column descriptors, is performed with the help of a principal component analysis on the retention data. Cross-column predictive performance of the final model is tested on a large external set consisting of retention data of 180 PBDEs collected in four separation conditions different from those considered in model calibration (different columns and/or temperature program). PMID:23726355

D'Archivio, Angelo Antonio; Giannitto, Andrea; Maggi, Maria Anna

2013-05-13

328

Pulse News  

NSDL National Science Digital Library

It can be quite fun to read the news, but about what the beauty of viewing a clutch of colorful news sites? Pulse is an "elegant news reading application" designed for the iPhone, Android, and other mobile devices. The application uses colorful panning story bars and populates them with content from sources (such as CNN, the BBC, and so on) selected by the user. Visitors can sign up for a free account, and they will also want to read over the FAQ section on the site.

2012-02-03

329

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

330

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

331

Twin column chromatography for industrial-scale decontamination processes  

Microsoft Academic Search

A frontal chromatographic unit was devised consisting of a column–detector–column array. The unit is either equipped with identical columns (identical twins) or with columns of varying length (fraternal twins). Due to the finite nature of the columns, a prerun is formed at the column walls following the same regularities as the main stream. These regularities are used for the identification

U. Wenzel; W. Ullrich

2004-01-01

332

Simplified Design of Batch Reactive Distillation Columns  

Microsoft Academic Search

This work proposes a simplified methodology for the analysis and design of reactive batch distillation columns based on the McCabe-Thiele method for reactive continuous columns and on the concept of a reactive difference point. To extend the application of the concept of a reactive difference point for reactive batch distillation columns, expressions for the McCabe-Thiele operating line and for the

Maria E. Huerta-Garrido; Vicente Rico-Ramirez; Salvador Hernandez-Castro

2004-01-01

333

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.

334

Maintenance of column performance at scale  

Microsoft Academic Search

Pack-in-place column packing methods were developed for Q Sepharose Big Beads at 40 cm I.D. and scaled up to 200 cm I.D. in Chromaflow columns. The efficiency and asymmetry of the packed bed were evaluated as a function of test velocity and sample volume. The performance of the packed beds at both scales approached the theoretical limits of column performance

Alan Williams; Kathy Taylor; Kyril Dambuleff; Owe Persson; Robert M Kennedy

2002-01-01

335

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

336

Fast pulsed electric field created from the self-generated filament of a femtosecond Ti:Sapphire laser pulse in air  

Microsoft Academic Search

We present an experiment demonstrating the generation of fast pulsed electric field from a plasma column created in air as a result of the interaction of N2 and O2 molecules with a 220 fs laser pulse. By first measuring the distribution of N2+ and then by measuring the net charge present at different positions in the focal region, we determined

A. Proulx; A. Talebpour; S. Petit; S. L Chin

2000-01-01

337

MRSQ informatics education columns: passing the baton.  

PubMed

This is the last Informatics Education column under the current editors. The outgoing co-editor identifies several key themes that describe the column during her tenure. The main theme discovered while reviewing the columns published over the last five years is technology. Technological changes and advances have affected the way in which librarians conduct instruction, such as incorporating e-learning with traditional workshops and in-class sessions. Technology plays a key role in all of the themes that emerged. The incoming editors imagine what the future themes will be for the Informatics Education column. PMID:23092421

Hasman, Linda; Hoberecht, Toni; Pullen, Kimberly

2012-01-01

338

Molecularly imprinted solid-phase extraction for the screening of antihyperglycemic biguanides.  

PubMed

A new molecularly imprinted polymer (MIP) was specifically synthesized as a smart material for the recognition of metformin hydrochloride in solid-phase extraction. Particles of this MIP were packed into a stainless-steel tubing (50 mm x 0.8 mm i.d.) equipped with an exit frit. This micro-column was employed in the development of a molecularly imprinted solid-phase extraction (MISPE) method for metformin determination. The MISPE instrumentation consisted of a micrometer pump, an injector valve equipped with a 20-microl sample loop, a UV detector, and an integrator. With CH3CN as the mobile phase flowing at 0.5 ml/min, 95 +/- 2% binding could be achieved for 1200 ng of metformin from one injection of a phosphate-buffered sample solution (pH 2.5). Methanol + 3% trifluoroacetic acid was good for quantitative pulsed elution (PE) of the bound metformin. The MISPE-PE method, with UV detection at 240 nm, afforded a detection limit of 16 ng (or 0.8 microg/ml) for metformin. However, the micro-column interacted indiscriminately with phenformin with a 49 +/- 2% binding. A systematic investigation of binding selectivity was conducted with respect to sample composition (including the solvent, matrix, pH, buffer and surfactant effects). An intermediate step of differential pulsed elution used acetonitrile with 5% picric acid to remove phenformin and other structural analogues. A final pulsed elution of metformin for direct UV detection was achieved using 3% trifluoroacetic acid in methanol. PMID:14971497

Feng, Sherry Y; Lai, Edward P C; Dabek-Zlotorzynska, Ewa; Sadeghi, Susan

2004-02-20

339

An Efficient Area-Delay Product Design for MixColumns\\/InvMixColumns in AES  

Microsoft Academic Search

MixColumns\\/InvMixColumns dominates both the logic resource and the critical delay in advanced encryption standard (AES) hardware implementation with direct mapping S-boxes. The proposed decomposition method optimizes the area and the delay of integrated MixColumns\\/InvMixColumns circuit. Theoretically, the proposed short-path circuit reduces the area up to 42% with the same 5 XOR gates delay (Y.-K. Lai et al, 2004) in critical

Chung-yi Li; Chih-feng Chien; Jin-hua Hong; Tsin-yuan Chang

2008-01-01

340

Comparison of supercritical fluid extraction and solvent extraction of twenty-two organochlorine pesticides from eggs.  

PubMed

The recoveries of twenty-two organochlorine pesticides spiked in egg samples were extracted by supercritical fluid extraction (SFE) using carbon dioxide and solvent extraction using acetonitrile were compared. The extracts were cleaned up with C18 and Florisil SPE columns. At 0.1 ppm spike level, the recoveries were 52 - 100% by SFE and 53 - 93% by solvent extraction. The limits of detection calculated at 0.01 ppm spike level were 0.072 - 0.006 ppm for SFE and 0.06 - 0.006 ppm for solvent extraction. Both methods show improvement in sample preparation time and solvent consumption from the existing Soxhlet extraction method. PMID:8867140

Wigfield, Y Y; Selwyn, J; Khan, S; McDowell, R

1996-03-01

341

Comparison of drug substance impurity profiles generated with extended length columns during packed-column SFC  

Microsoft Academic Search

The current study assesses the effect of extending column length during gradient packed column sub\\/supercritical fluid chromatography (PCSFC) experiments on the detection of known and unknown impurities in a drug substance sample. Quantitative drug substance impurity profiles were generated and compared using multiple column PCSFC and HPLC conditions. Also, chromatographic figures of merit were estimated and compared for components of

Daryl A Roston; Saleem Ahmed; Doug Williams; Tom Catalano

2001-01-01

342

Ultimate Capacity of Steel Columns Loaded Biaxially.  

National Technical Information Service (NTIS)

The problem was to theoretically predict the ultimate capacity of columns loaded biaxially, i.e., columns subjected to an axial load plus terminal bending moments about two principal axes of the cross-section. The material was mild steel and the cross-sec...

J. S. Ellis E. J. Jury D. W. Kirk

1964-01-01

343

Column cellulose hydrolysis reactor: Cellulase adsorption profile  

Microsoft Academic Search

A column cellulose hydrolysis reactor was set up using a single passage of cellulase enzyme which was followed with a continuous percolation of buffer. Hydrolysis rates were found to decline precipitously upon the removal of the non-adsorbed cellulase components. By comparing specific activities of the cellulase before and after adsorption on the cellulose column, it was concluded that the adsorption

Larry U. L. Tan; Ernest K. C. Yu; Paul Mayers; John N. Saddler

1986-01-01

344

Numerically optimized performance of diabatic distillation columns  

Microsoft Academic Search

Recently, the concept of equal thermodynamic distance (ETD) has been proposed to minimize entropy production in a distillation process using a diabatic column. ETD gives the optimal temperature profile to first-order in N?1, where N is the number of trays. ETD, however, does not generally give the true minimum for distillation columns with few trays. We therefore apply a fully

Markus Schaller; Karl Heinz Hoffmann; Gino Siragusa; Peter Salamon; Bjarne Andresen

2001-01-01

345

Isolation of Column Phenomena in Gas Chromatography.  

National Technical Information Service (NTIS)

The sole objective of the research project was to assemble a gas chromatograph for Chromatography Laboratory. An attempt has been made to isolate the broadening that is caused by the column alone, from that which is due to column plus all other factors. T...

M. Shahid

1974-01-01

346

Mechanical interactions of UIS support columns. [LMFBR  

Microsoft Academic Search

Code development involving above-core structures (ACS) has recently focused on modeling the complexities of mechanical interactions in the ACS support columns which play a very important role in their behavior. These developments are directed toward two considerations: (1) the prediction of the forces exerted by the column in a hypothetical core-disruptive accident (HCDA) in order that the motion of the

J. M. Kennedy; T. B. Belytschko

1983-01-01

347

Choosing an HPLC Column for Carbohydrate Analyses  

Microsoft Academic Search

Chemical and physical properties among monosaccharides, disaccharides, and trisaccharides differ only slightly. Hence, HPLC separations of carbohydrates depend on differences in conformation, configuration, and bonding mode, and are more difficult than analyses of other classes of compounds. No single HPLC column or method is capable of separating all carbohydrates. For this reason, we offer a selection of columns specifically prepared

E. I. Doughty

1995-01-01

348

Column size effects of DER fluids  

NASA Astrophysics Data System (ADS)

The static yield stress of dielectric electrorheological (DER) fluids of infinite column state and chain state are calculated from the first principle method. The results indicate that the column surface contributions to ER effects is very small and both states will give correct results to the real DER fluids.

Zhao, T.; Ma, H. R.

2001-07-01

349

29 CFR 1926.755 - Column anchorage.  

Code of Federal Regulations, 2013 CFR

...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) located 18 inches (.46m) from the extreme outer face of...

2013-07-01

350

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.

351

Maintenance of column performance at scale.  

PubMed

Pack-in-place column packing methods were developed for Q Sepharose Big Beads at 40 cm I.D. and scaled up to 200 cm I.D. in Chromaflow columns. The efficiency and asymmetry of the packed bed were evaluated as a function of test velocity and sample volume. The performance of the packed beds at both scales approached the theoretical limits of column performance (Hred =2 and Af=1) expected in small analytical columns. The packing strategy was effective for scale up and the stability of the packed beds, the effectiveness of the column design with respect to the mobile phase distribution system and the stability of the media to the pack-in-place technology, are presented. PMID:11831765

William, Alan; Taylor, Kathy; Dambuleff, Kyril; Persson, Owe; Kennedy, Robert M

2002-01-25

352

Composite Column Design/Test Lab  

NSDL National Science Digital Library

Effective engineered composite design activities require predictive and quantitative methodology. This research incorporates engineering design, using smart spreadsheets, into a laboratory activity focusing on columns made of composite materials. In a previous work, a laboratory activity was developed supporting composite design of polymer matrix composite beams. The present work applies a similar approach expanded to ceramic composites in the form of columns. In the lab, students simulate composite columns and use a smart spreadsheet to help optimize their design for engineering performance, including specific properties. Parameters are discussed and evaluated before the column is made. The composite is then fabricated. Finally, the composite is tested and the experimental data (critical load for columns) is compared to predictions.

Johnson, Craig

2009-09-22

353

A sensitive semi-micro column HPLC method with peroxyoxalate chemiluminescence detection and column switching for determination of MDMA-related compounds in hair  

Microsoft Academic Search

A sensitive semi-micro column HPLC method with peroxyoxalate chemiluminescence (POCL) detection and column switching has been\\u000a developed for simultaneous determination of 3,4-methylenedioxymethamphetamine (MDMA) and related compounds, for example 3,4-methylenedioxyamphetamine,\\u000a methamphetamine, and amphetamine, in hair. After digestion of the hair with 1 mol L?1 sodium hydroxide the compounds were extracted with n-heptane and derivatized with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole. A mixture of hydrogen peroxide and

Shinichi Nakamura; Mitsuhiro Wada; Brian L. Crabtree; Patricia M. Reeves; John H. Montgomery; H. Joseph Byrd; Shiro Harada; Naotaka Kuroda; Kenichiro Nakashima

2007-01-01

354

Effect of pressure drop on solute retention and column efficiency in supercritical fluid chromatography.  

PubMed

The effect of pressure drop on the performance of supercritical fluid chromatographic systems is studied. Experiments have been conducted at different pressures and at 55 and 65 degrees C. Experiments at conditions leading to large and small pressure drops have been performed. Parameters to describe the pressure drop, retention time and efficiency have been extracted from these experiments. Using these parameters the dynamics of the chromatographic column have been modeled. Darcy's law was used to describe the pressure drop. The efficiency was modeled by considering the contributions from axial dispersion, resistance to mass transfer from the fluid film, and to diffusion in the pores. Good description of the pressure drop, retention time and mass transfer characteristics under normal operating conditions was obtained. The parameters extracted were used to predict the elution profile by numerical simulations. Considerable loss in column efficiency was observed when operating the column at lower values of the back pressure. PMID:16188570

Rajendran, Arvind; Kräuchi, Oliver; Mazzotti, Marco; Morbidelli, Massimo

2005-10-21

355

Solid Phase Extraction of Solanesol  

Microsoft Academic Search

The method of solid-phase extraction (SPE) for the concentration and clean-up of tobacco extract samples during solanesol\\u000a analysis was proposed in this work. A column (200 mm  4 mm i.d.) packed with 0.10 g silica gel (with particle size of 70 ?m,\\u000a porosity of 0.5 and surface area of 400 m2 g?1) was used as SPE cartridge. Several extraction parameters, such as sample loading flow (0.3–7 mL min?1), sample

De-Song Tang; Hui-Ling Liang; Lin Zhang; Huan-Lin Chen

2007-01-01

356

PSR beam-pulse formation and control  

SciTech Connect

The Proton Storage Ring (PSR) is a major addition to the Weapons Neutron Research Facility (WNR) at LAMPF. It will act as a bunch compressor for the relatively long linac macropulses from LAMPF, tailoring them into short, intense pulses ideally suited for neutron-scattering research. This paper concentrates on the methods used to form these pulses before injection into the linac, to multiplex the PSR beam with other LAMPF users, and to synchronize the storage ring with pulse arrival time at injection and with the WNR mechanical neutron chopper at extraction.

Hardekopf, R.A.

1983-01-01

357

A new essential oil Chemotype of Allium roseum analysed by an apolar column  

Microsoft Academic Search

This study deals with the chemical characterization of a medicinal and an aromatic plant of the Tunisian flora: Allium roseum var. odoratissimum, and aimed to identify new bioactive natural compounds in its flower essential oil. These compounds were extracted by hydrodistillation and analysed by GC and GC\\/MS, using an apolar column. The most important compounds characterized were organo-sulphurous (46%), including

Sami Zouari; Hanen Najjaa; Mohamed Neffati; Emna Ammar

2011-01-01

358

Lead uptake by algae Gelidium and composite material particles in a packed bed column  

Microsoft Academic Search

Biosorption of lead ions was studied in a flow-through column packed with red algae Gelidium and a composite material (industrial algal waste from the agar extraction process immobilized with polyacrylonitrile). Experiments were performed in order to study the effect of important design parameters such as flow rate and influent pH. The breakthrough curves for lead and proton concentrations were obtained

Vítor J. P. Vilar; Cidália M. S. Botelho; Rui A. R. Boaventura

2008-01-01

359

Application of monolithic column in quantification of gliclazide in human plasma by liquid chromatography  

Microsoft Academic Search

A simple, rapid and sensitive isocratic reversed phase HPLC method with UV detection using a monolithic column has been developed and validated for the determination of gliclazide in human plasma. The assay enables the measurement of gliclazide for therapeutic drug monitoring with a minimum quantification limit of 10ngml?1. The method involves simple, one-step extraction procedure and analytical recovery was complete.

S. M. Foroutan; A. Zarghi; A. Shafaati; A. Khoddam

2006-01-01

360

Laser breakdown in alcohols and water induced by ? = 1064 nm nanosecond pulses  

Microsoft Academic Search

Laser breakdown, induced by nanosecond pulses of 1064nm wavelength, was studied in four alcohols and in water. The time dependent structure and physical properties of the breakdown were measured at high temporal and spatial resolutions, using Mach–Zehnder interferometry, shadow and Schlieren diagnostic techniques. The results indicate that just after the laser pulse the spark column has essentially discrete character and

Tatiana Kovalchuk; Gregory Toker; Valery Bulatov; Israel Schechter

2010-01-01

361

Use of specially designed columns for antioxidants and antimicrobials enrichment by preparative supercritical fluid chromatography.  

PubMed

A new, specially designed column has been developed for fractionation of supercritical fluid extract of rosemary by using a preparative supercritical fluid chromatography system (Prep-SFC). The column evaluated in this work was prepared using a new packing method consisting of a combination of slurry and supercritical CO2 with commercial silica particles coated with a stationary phase commonly used in gas chromatography, such as SE-54 (5% phenyl-, 95% methylsilicone). The new packing procedure provided columns with reasonable efficiencies, with high stability and useful at high-pressure range. A 25 cm x 10 mm i.d. column packed with silica particles coated with 3% of SE-54 was prepared, and its separation power was tested for isolating fractions with high antioxidant and/or antimicrobial activity from a supercritical rosemary extract. The SFC conditions were selected based on a previous work done with a commercial LC-Diol packed column (130 bar, 80 degrees C), and different percentages of modifier in the mobile phase were tested (5 and 10%). Two cyclones were employed to collect the fractions which were then characterized by HPLC-diode array detection (DAD), GC, and in vitro antioxidant and antimicrobial assays. The use of coated packed columns allowed the fractionation of a complex mixture of rosemary supercritical extract with a minimum amount of modifier in the mobile phase (5% ethanol). At the optimum conditions it was possible to obtain two very active fractions in terms of antioxidant and antimicrobial activity, with no residual rosemary aroma and with improved activities compared to the original supercritical extract. PMID:17224159

Ramírez, Pilar; Santoyo, Susana; García-Risco, Mónica R; Señoráns, F Javier; Ibáñez, Elena; Reglero, Guillermo

2007-01-08

362

Single column locking plate fixation is inadequate in two column acetabular fractures. A biomechanical analysis  

PubMed Central

Background The objective of this study was to determine whether one can achieve stable fixation of a two column (transverse) acetabular fracture by only fixing a single column with a locking plate and unicortical locking screws. We hypothesized that a locking plate applied to the anterior column of a transverse acetabular fracture would create a construct that is more rigid than a non-locking plate, and that this construct would be biomechanically comparable to two column fixation. Methods Using urethane foam models of the pelvis, we simulated transverse acetabular fractures and stabilized them with 1) an anterior column plate with bicortical screws, 2) an anterior locking plate with unicortical screws, 3) an anterior plate and posterior column lag screw, and 4) a posterior plate with an anterior column lag screw. These constructs were mechanically loaded on a servohydraulic material testing machine. Construct stiffness and fracture displacement were measured. Result and Discussion We found that two column fixation is 54% stiffer than a single column fixation with a conventional plate with bicortical screws. There was no significant difference between fixation with an anterior column locking plate with unicortical screws and an anterior plate with posterior column lag screw. We detected a non-significant trend towards more stiffness for the anterior locking plate compared to the anterior non-locking plate. Conclusion In conclusion, a locking plate construct of the anterior column provides less stability than a traditional both column construct with posterior plate and anterior column lag screw. However, the locking construct offers greater strength than a non-locking, bicortical construct, which in addition often requires extensive contouring and its application is oftentimes accompanied by the risk of neurovascular damage.

2010-01-01

363

Liquid dispersion and gas holdup in packed bubble columns at atmospheric pressure  

Microsoft Academic Search

The gas holdup and liquid axial dispersion coefficient are measured in two semibatch packed bubble columns, 0.154 and 0.200m diameter for an air–water system, at atmospheric conditions. It is observed that the one-dimensional dispersion model does not give an accurate description of the tracer concentration profiles from a pulse injection. This is due to convective liquid flows inside the bed

Peter Therning; Anders Rasmuson

2001-01-01

364

The role of colloidal kaolinite in the transport of cesium through laboratory sand columns  

Microsoft Academic Search

Recent laboratory and field studies indicate that colloids are capable of adsorbing and enhancing the transport of a variety of contaminants in groundwater. We examined the influence of kaolinite particles on ¹³⁷Cs movement through sand columns. The times for transport of the main part of the ¹³⁷Cs pulse decreased by over a factor of 2 as the concentration of kaolinite

James E. Saiers; George M. Hornberger

1996-01-01

365

Breaking Row and Column Symmetries in Matrix Models  

Microsoft Academic Search

We identify an important class of symmetries in constraint programming, arising from matrices of decision variables where rows and columns can be swapped. Whilst lexicographically ordering the rows (columns) breaks all the row (column) symmetries, lexicographically or- dering both the rows and the columns fails to break all the compositions of the row and column symmetries. Nevertheless, our experimental re-

Pierre Flener; Alan M. Frisch; Brahim Hnich; Zeynep Kiziltan; Ian Miguel; Justin Pearson; Toby Walsh

2002-01-01

366

Demonstration of the Feasibility of Radially Compressed Microbore HPLC Columns  

Microsoft Academic Search

This work involved the development of radially compressed, microbore high performance liquid chromatography (HPLC) columns. The design of the overall system and the column are described, and the problems associated with the design features are reported. Variables examined during the course of this work included the column material, column length, packing method, flow rate, radial compression pressure, and internal column

P. A. Hyldburg; C. M. Sparacino; J. W. Hines; C. D. Keller

1987-01-01

367

Pulse-burst laser systems for fast Thomson scattering (invited).  

PubMed

Two standard commercial flashlamp-pumped Nd:YAG (YAG denotes yttrium aluminum garnet) lasers have been upgraded to "pulse-burst" capability. Each laser produces a burst of up to 15 2 J Q-switched pulses (1064 nm) at repetition rates of 1-12.5 kHz. Variable pulse-width drive (0.15-0.39 ms) of the flashlamps is accomplished by insulated gate bipolar transistor (IGBT) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, and up to four 2 J laser pulses during one flashlamp pulse. These lasers are used in the Thomson scattering plasma diagnostic system on the MST reversed-field pinch to record the dynamic evolution of the electron temperature profile and temperature fluctuations. To further these investigations, a custom pulse-burst laser system with a maximum pulse repetition rate of 250 kHz is now being commissioned. PMID:21033868

Den Hartog, D J; Ambuel, J R; Borchardt, M T; Falkowski, A F; Harris, W S; Holly, D J; Parke, E; Reusch, J A; Robl, P E; Stephens, H D; Yang, Y M

2010-10-01

368

Pulse-burst laser systems for fast Thomson scattering (invited)  

NASA Astrophysics Data System (ADS)

Two standard commercial flashlamp-pumped Nd:YAG (YAG denotes yttrium aluminum garnet) lasers have been upgraded to ``pulse-burst'' capability. Each laser produces a burst of up to 15 2 J Q-switched pulses (1064 nm) at repetition rates of 1-12.5 kHz. Variable pulse-width drive (0.15-0.39 ms) of the flashlamps is accomplished by insulated gate bipolar transistor (IGBT) switching of electrolytic capacitor banks. Direct control of the laser Pockels cell drive enables optimal pulse energy extraction, and up to four 2 J laser pulses during one flashlamp pulse. These lasers are used in the Thomson scattering plasma diagnostic system on the MST reversed-field pinch to record the dynamic evolution of the electron temperature profile and temperature fluctuations. To further these investigations, a custom pulse-burst laser system with a maximum pulse repetition rate of 250 kHz is now being commissioned.

den Hartog, D. J.; Ambuel, J. R.; Borchardt, M. T.; Falkowski, A. F.; Harris, W. S.; Holly, D. J.; Parke, E.; Reusch, J. A.; Robl, P. E.; Stephens, H. D.; Yang, Y. M.

2010-10-01

369

Column efficiency in micellar electrokinetic capillary chromatography  

SciTech Connect

Experimental factors that influence column efficiency in micellar electrokinetic capillary chromatography were studied. Parameters, such as applied voltage, column dimensions, and concentrations of buffer and surfactant in the mobile phase, are found to influence efficiency. Van Deemter-like plots of plate vs. applied voltage are used to demonstrate the significance of factors which typically cause band dispersion in chromatography and electrophoresis. Dispersion due to resistance to mass transfer in the mobile phase and temperature gradients within the column are shown to be most significant. Plate heights of less than 10..mu..m are possible when experimental parameters are optimized.

Sepaniak, M.J.; Cole, R.O.

1987-02-01

370

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

371

Extraction of Anthracyclines from Biological Fluids for HPLC Evaluation  

Microsoft Academic Search

A new technique for the extraction of anthracyclines and their metabolites from plasma or serum is described, which gives suitable extracts for HPLC analysis of these drugs in patients. This technique consists in a very rapid chromatographic step on the bonded silica contained in small open columns (C-18 Sep-Paks, Waters Associates). This extraction gives quantitative recoveries of all the anthracyclines

Jacques Robert

1980-01-01

372

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

Microsoft Academic Search

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

Oleg B. Egorov; Matthew J. OHara; Jay W. Grate; Darrell P. Chandler; Fred J. Brockman; Cynthia J. Bruckner-Lea

2000-01-01

373

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

Microsoft Academic Search

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

Oleg B. Egorov; Matthew J. OHara; Jay W. Grate; Darrell P. Chandler; Fred J. Brockman; Cynthia J. Bruckner-Lea

2006-01-01

374

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

Microsoft Academic Search

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

Oleg B. Egorov; Matthew J. OHara; Jay W. Grate; Darrell P. Chandler; Fred J. Brockman; Cynthia J. Bruckner-Lea

2004-01-01

375

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...

376

Molten salt extractive distillation process for zirconium-hafnium separation  

SciTech Connect

This patent describes an improvement in a process for zirconium-hafnium separation. It utilizes an extractive distillation column with a mixture of zirconium and hafnium tetrachlorides introduced into a distillation column having a top and bottom with hafnium enriched overheads taken from the top of the column and a molten salt solvent circulated through the column to provide a liquid phase, and with molten salt solvent containing zirconium chloride being taken from the bottom of the distillation column. The improvements comprising: utilizing a molten salt solvent consisting principally of lithium chloride and at least one of sodium, potassium, magnesium and calcium chlorides; stripping of the zirconium chloride taken from the bottom of the distillation column by electrochemically reducing zirconium from the molten salt solvent; and utilizing a pressurized reflux condenser on the top of the column to add the hafnium chloride enriched overheads to the molten salt solvent previously stripped of zirconium chloride.

McLaughlin, D.F.; Stoltz, R.A.

1989-10-17

377

Evaluation of Stone Column Stabilized Embankment Foundation.  

National Technical Information Service (NTIS)

The report documents construction procedures, monitors field performance, and make recommendations concerning the effectiveness and future use of a foundation improvement procedure using stone columns for stabilization. The effort was executed by use of f...

B. W. Meade D. L. Allen

1985-01-01

378

Unified Positive Column Theory of Gas Discharges.  

National Technical Information Service (NTIS)

The effects of electron impact ionization, three-body recombination, and a thermal energy balance are considered on the positive column of a gas discharge confined between plane parallel walls. The diffusion flux equations (with temperature dependent ioni...

I. M. Cohen A. M. Whitman

1972-01-01

379

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

380

Limit State Design of Columns Fabricated from Slender Plates.  

National Technical Information Service (NTIS)

The multiple column curve concept was adopted in the draft Australian Limit State Steel Structures Standard. The report describes the philosophy behind the column design approach used in the draft standard, and how appropriate column curves were selected ...

K. J. R. Rasmussen A. J. Davids G. J. Hancock

1989-01-01

381

The shape of the strongest column  

Microsoft Academic Search

The problem of determining that shape of column which has the largest critical buckling load is solved, assuming that the\\u000a length and volume are given and that each cross section is convex. The strongest column has an equilateral triangle as cross\\u000a section, and it is tapered along its length, being thickest in the middle and thinnest at its ends. Its

Joseph B. Keller

1960-01-01

382

Rectangular Tubular Steel Columns Loaded Biaxially  

Microsoft Academic Search

An inelastic analysis of rectangular tubular steel columns subjected to a constant axial load and a gradually increasing biaxial end moment is presented. Analytical thrust-moment-curvature relationships are given for the cross section with bilinear material stress-strain characteristics. An iterative procedure based on column deflection curves is used to predict moment-deflection curves up to collapse, and numerical examples are given for

Zia Razzaq; William W. McVinnie

1982-01-01

383

Gapped pulses for frequency-swept MRI.  

PubMed

A recently introduced method called SWIFT (SWeep Imaging with Fourier Transform) is a fundamentally different approach to MRI which is particularly well suited to imaging objects with extremely fast spin-spin relaxation rates. The method exploits a frequency-swept excitation pulse and virtually simultaneous signal acquisition in a time-shared mode. Correlation of the spin system response with the excitation pulse function is used to extract the signals of interest. With SWIFT, image quality is highly dependent on producing uniform and broadband spin excitation. These requirements are satisfied by using frequency-modulated pulses belonging to the hyperbolic secant family (HSn pulses). This article describes the experimental steps needed to properly implement HSn pulses in SWIFT. In addition, properties of HSn pulses in the rapid passage, linear region are investigated, followed by an analysis of the pulses after inserting the "gaps" needed for time-shared excitation and acquisition. Finally, compact expressions are presented to estimate the amplitude and flip angle of the HSn pulses, as well as the relative energy deposited by the SWIFT sequence. PMID:18554969

Idiyatullin, Djaudat; Corum, Curt; Moeller, Steen; Garwood, Michael

2008-05-20

384

Gapped Pulses for Frequency-Swept MRI  

PubMed Central

A recently introduced method called SWIFT (SWeep Imaging with Fourier Transform) is a fundamentally different approach to MRI which is particularly well suited to imaging objects with extremely fast spin-spin relaxation rates. The method exploits a frequency-swept excitation pulse and virtually simultaneous signal acquisition in a time-shared mode. Correlation of the spin system response with the excitation pulse function is used to extract the signals of interest. With SWIFT, image quality is highly dependent on producing uniform and broadband spin excitation. These requirements are satisfied by using frequency-modulated pulses belonging to the hyperbolic secant family (HSn pulses). This article describes the experimental steps needed to properly implement HSn pulses in SWIFT. In addition, properties of HSn pulses in the rapid passage, linear region are investigated, followed by an analysis of the pulses after inserting the “gaps” needed for time-shared excitation and acquisition. Finally, compact expressions are presented to estimate the amplitude and flip angle of the HSn pulses, as well as the relative energy deposited by the SWIFT sequence.

Idiyatullin, Djaudat; Corum, Curt; Moeller, Steen; Garwood, Michael

2008-01-01

385

EVALUATION OF CAPILLARY SYSTEMS FOR THE ANALYSIS OF ENVIRONMENTAL EXTRACTS  

EPA Science Inventory

The quantitative and qualitative aspects of splitless and on-column capillary column injectors for the analysis of environmental extracts for priority pollutants are investigated. Precision data are presented for a wide variety of compounds introduced into a splitless injector by...

386

Padronizacao da dosagem de diidrotestosterona por radioimunoensaio apos cromatografia em coluna de celite. (Measurement of dihydro testosterone by radioimmunoassay after celite column chromatography).  

National Technical Information Service (NTIS)

A method for measuring dihydro testosterone after celite column chromatography is developed. One milliliter of serum containing 1000 cpm of tritiated dihydro testosterone was extracted with hexane: ethyl acetate (2:3): dried, diluted with non saturated is...

V. S. Lando

1992-01-01

387

Comparison of Commercial Column Types in Liquid Chromatography  

Microsoft Academic Search

Several commercially available liquid chromatographic column types have been experimentally evaluated. A conventionally-sized column containing 5 ?m packing, a microbore column containing 10 ?m packing, a column containing 3 ?m packing, and two short, wide-bore columns containing 5 ?m packing were compared at optimum velocity (van Deemter minimum) and at twice the optimum velocity where possible. All columns contained reversed-phase

R. W. McCoy; R. E. Pauls

1982-01-01

388

Affinity-based screening of combinatorial libraries using automated, serial-column chromatography  

SciTech Connect

The authors have developed an automated serial chromatographic technique for screening a library of compounds based upon their relative affinity for a target molecule. A {open_quotes}target{close_quotes} column containing the immobilized target molecule is set in tandem with a reversed-phase column. A combinatorial peptide library is injected onto the target column. The target-bound peptides are eluted from the first column and transferred automatically to the reversed-phase column. The target-specific peptide peaks from the reversed-phase column are identified and sequenced. Using a monoclonal antibody (3E-7) against {beta}-endorphin as a target, we selected a single peptide with sequence YGGFL from approximately 5800 peptides present in a combinatorial library. We demonstrated the applicability of the technology towards selection of peptides with predetermined affinity for bacterial lipopolysaccharide (LPS, endotoxin). We expect that this technology will have broad applications for high throughput screening of chemical libraries or natural product extracts. 21 refs., 4 figs.

Evans, D.M.; Williams, K.P.; McGuinness, B. [PerSeptive Biosystems, Framingham, MA (United States)] [and others

1996-04-01

389

Influence of pulsed arc parameters on powder production in ethanol  

Microsoft Academic Search

Powder consisting nickel and carbon particles were synthesized using a pulsed arc between Ni electrodes submerged in pure ethanol. The ethanol was arc treated for 5 min with 20 and 40 ?s duration pulses, at a repetition rate of 100 Hz. The pulse energy was varied in a range of 7.7–192 mJ. Powder samples were obtained by extracting liquid from

N. Parkansky; G. Frenkel; B. Alterkop; R. L. Boxman; S. Goldsmith; Z. Barkay; Yu. Rosenberg; O. Goldstein

2006-01-01

390

Tumour blood flow changes induced by application of electric pulses  

Microsoft Academic Search

The effect of electric pulses on tumour blood flow was investigated in the murine fibrosarcoma SA-1. After the application of short intense electric pulses, relative tumour perfusion was measured using an 86RbCl extraction technique. A significant reduction of tumour perfusion (?30% of control) was observed within 1h following the application of eight electric pulses to the tumour. Thereafter, tumour blood

C. S. Parkins; D. J. Chaplin

1999-01-01

391

PULSED POWER APPLICATIONS IN HIGH INTENSITY PROTON RINGS.  

SciTech Connect

Pulsed power technology has been applied in particle accelerators and storage rings for over four decades. It is most commonly used in injection, extraction, beam manipulation, source, and focusing systems. These systems belong to the class of repetitive pulsed power. In this presentation, we review and discuss the history, present status, and future challenge of pulsed power applications in high intensity proton accelerators and storage rings.

ZHANG, S.Y.; SANDBERG, J.; ET AL.

2005-05-16

392

‘Column on column’ structures as indicators of lava\\/ice interaction, Ruapehu andesite volcano, New Zealand  

Microsoft Academic Search

Lava flows of the Mangawhero Formation (ca. 15–60 ka) on Ruapehu volcano erupted during the last glaciation. In a distal flow lobe at Tukino, on the east side of the mountain, small secondary columns (10–20 cm thick) have formed on the sides of large, rectangular, primary (0.5–3 m thick) cooling columns. Thick (10 m+) zones of such small columns form a lateral and basal

K. B. Spörli; J. V. Rowland

2006-01-01

393

Enhanced transport of colloidal oil droplets in saturated and unsaturated sand columns.  

PubMed

Colloidal-sized triacylglycerol droplets demonstrated enhanced transport compared to ideal latex colloid spheres in both saturated and unsaturated quartz sand columns. Oil droplets (mean diameter 0.74 ± 0.03 ?m, density 0.92 g cm(-3), ?-potential -34 ± 1 mV) were injected simultaneously with latex microsphere colloids (FluoSpheres; density 1.055 g cm(-3), diameters 0.02, 0.2, and 1.0 ?m, ?-potentials -16 ± 1, -30 ± 2, and -49 ± 1, respectively) and bromide into natural quartz sand (?-potential -63 ± 2 mV) via short-pulse column breakthrough experiments. Tests were conducted under both saturated and unsaturated conditions. Breakthrough of oil droplets preceded bromide and FluoSpheres. Recovery of oil droplets was 20% greater than similarly sized FluoSpheres in the saturated column, and 16% greater in the 0.18 ± 0.01 volumetric water content (VWC) unsaturated column. Higher variability was observed in the 0.14 ± 0.01 VWC column experiments with oil droplet recovery only slightly greater than similarly sized FluoSpheres. The research presents for the first time the direct comparison of colloidal oil droplet transport in porous media with that of other colloids, and demonstrates transport under unsaturated conditions. Based on experimental results and theoretical analyses, we discuss possible mechanisms that lead to the observed enhanced mobility of oil droplets compared to FluoSpheres with similar size and electrostatic properties. PMID:21950652

Travis, Micheal J; Gross, Amit; Weisbrod, Noam

2011-10-11

394

A capillary column gas-chromatographic method for the identification of drugs of abuse in urine samples.  

PubMed

This paper describes the application of capillary column gas liquid chromatography (GLC) to the analysis of urine samples for drugs of abuse. A simple basic extraction into butylacetate is followed by temperature programmed analysis from 90 degrees C to 310 degrees C to provide a comprehensive screen for basic drugs. Retention data are presented for approximately 300 compounds. The use of capillary column GLC is compared with packed column methods used previously in this laboratory. The reproducibility of retention data and sensitivity of this analysis for several commonly encountered drugs are presented. PMID:2817754

Caldwell, R; Challenger, H

1989-09-01

395

Automated metal-free multiple-column nanoLC for improved phosphopeptide analysis sensitivity and throughput  

SciTech Connect

We report on the development and characterization of an automated metal-free nanoscale multiple-capillary system for reversed-phase liquid chromatography-mass spectrometry analysis of phosphopeptides. The system incorporates a capillary column (50 um i.d. × 30 cm, packed with 5 um C18 particles) coupled on-line to a solid phase extraction column (150 um i.d. × 4 cm, packed with 5 um C18 particles). Electrospray ionization tips are constructed on the packed capillary column to couple the reversed-phase liquid chromatographic separation to a linear ion trap tandem mass spectrometer.

Zhao, Rui; Ding, Shi-Jian; Shen, Yufeng; Camp, David G.; Livesay, Eric A.; Udseth, Harold R.; Smith, Richard D.

2009-03-15

396

Nonlinear transmission line (NLTL) design as a pulse generator  

Microsoft Academic Search

Computer simulations are performed to optimize the number of sections in a tapered NLTL generating a pulse signal. The Schottky diode model is used based on physical simulation using Silvaco. The extracted CV characteristics are fitted to a hyperbolic function. The effect of the input frequency on the output pulse is investigated

D. Salamh; D. Linton

1996-01-01

397

Faster axial band dispersion in a monolithic silica column than in a particle-packed column.  

PubMed

The contribution of molecular diffusion to peak broadening was studied in a reversed-phase HPLC system, consisting of a monolithic silica C18 column and methanol-water mobile phase. Study on the band broadening effect of holding a solute in a column or elution at very low linear velocity of mobile phase allowed facile determination of the contribution of the molecular diffusion term. Less obstruction against molecular diffusion, or the faster axial band dispersion in a monolithic silica column than in a particle-packed column, was found both in mobile phase and in stationary phase. PMID:16360662

Kobayashi, Hiroshi; Tokuda, Daisuke; Ichimaru, Jun; Ikegami, Tohru; Miyabe, Kanji; Tanaka, Nobuo

2005-12-19

398

Detachment of Bacteria From Porous Media in Laboratory Columns  

NASA Astrophysics Data System (ADS)

Extended tailing, the continued elution of bacteria at low concentrations, has often been observed in breakthrough curves during both laboratory and field transport experiments. Tailing is caused by the slow detachment (also referred to as entrainment or desorption) of previously attached cells over time, with aqueous concentrations often orders of magnitude below the peak concentration. This transfer of bacteria from the solid phase to the aqueous phase results in the long-term release of bacteria back into drinking water supplies, posing potential human health risks. Unlike the factors controlling bacterial attachment to aquifer sediments, the processes controlling bacterial detachment from sediment surfaces are not well understood. We performed laboratory column experiments to investigate the transport and detachment of Escherichia coli (E. coli) at resting state through uncoated and Fe-coated quartz sand in KCl solution at low and high ionic strength (0.001-0.01 M). A one-half pore volume pulse of 3[H]-labeled E. coli was injected into flow-through columns, and column effluent was sampled for approximately 18 pore volumes. To account for biological effects on detachment, experiments were also run using E. coli treated with 0.5% formaldehyde. To calculate bacterial detachment rates, we fit the one dimensional advection-dispersion equation modified to account for deposition (Kf) and detachment (Kr) to the breakthrough curves for each treatment combination. In general, higher (Kr) values were observed under conditions less conducive to irreversible attachment, such as low ionic strength and uncoated sands. Tailing was not observed for experiments using Fe-coated sands, indicating that iron-coated sands irreversibly removed bacteria from the water column. There were no significant differences between fixed and live cells, indicating that bacterial cells at resting state behave like inorganic colloids, which suggests that under these conditions biological effects on attachment and detachment are minimal. Our results indicate that iron-coated sediments can permanently remove bacteria from groundwater under certain conditions. This knowledge is valuable for protecting groundwater supplies from contamination by pathogenic microorganisms.

Strauss, J. L.; Bolster, C. H.

2004-05-01

399

Electrochemical uranium valence control in centrifugal solvent extraction contactors  

SciTech Connect

In the Purex process for the reprocessing of spent nuclear fuel, the partitioning of uranium and plutonium generally requires a reducing agent for the valence change of Pu(IV) to Pu(III). Modified mixer-settlers and pulsed columns with internal electrodes have been developed for the simultaneous electroreduction and solvent extraction, and the utility of this partitioning method has been demonstrated for the reprocessing of light water reactor and fast breeder reactor (FBR) fuels. Short-residence solvent extraction contractors are needed for the reprocessing of high-burnup fuels to reduce the radiation damage to the organic solvent. Centrifugal contactors, the currently preferred machines, have inherent spatial limitations for the incorporation of electrodes. External electrolytic reduction cells could be used, provided the chemical stability of the reduced species (U(IV) and Pu(III)) can be assured. The feasibility of in-tandem operation of a multistage centrifugal contactor and an electrolytic reduction cell was investigated, and the applicability of this method to the reprocessing of FBR fuel was tested by means of computer models developed from experimental results.

Schneider, A.; Pschirer, D.M.

1988-01-01

400

Recovery of aromatics from pyrolysis gasoline by conventional and energy-integrated extractive distillation  

Microsoft Academic Search

Extractive distillation is widely used technology for recovering aromatics from different feedstock. This study investigates the recovery of aromatics which has an important commercial application such as benzene, toluene and xylenes from pyrolysis gasoline using a solvent called N-methylpyrolidone. The study also examines the procedures involved in implementing the energy-integrated extractive distillation technologies such as Petlyuk column, divided wall column

Faten Abushwireb; Hadi Elakrami; Mansour Emtir

2007-01-01

401

Quantitative capillary column gas chromatographic method for the determination of glycopyrronium in human plasma.  

PubMed

A new sensitive and selective capillary column gas chromatographic method for the anti-cholinergic agent glycopyrronium bromide in human plasma is described. The procedure involves preliminary ion-pair extraction of the drug into dichloromethane, followed by concentration and analysis of the ion-pair complex by capillary column gas chromatography using a nitrogen-sensitive detector. The method depends on the thermal dequaternisation of the quaternary ammonium compound and can be used to detect 5 ng/ml in a 3-ml plasma sample. The assay procedure has been applied to the determination of the plasma concentration of glycopyrronium after intravenous administration to an anaesthetised patient. PMID:6746811

Murray, G R; Calvey, T N; Williams, N E; Chan, K

1984-06-01

402

DIFFERENTIAL PULSE HEIGHT DISCRIMINATOR  

DOEpatents

Pulse-height discriminators are described, specifically a differential pulse-height discriminator which is adapted to respond to pulses of a band of amplitudes, but to reject pulses of amplitudes greater or less than tbe preselected band. In general, the discriminator includes a vacuum tube having a plurality of grids adapted to cut off plate current in the tube upon the application of sufficient negative voltage. One grid is held below cutoff, while a positive pulse proportional to the amplltude of each pulse is applled to this grid. Another grid has a negative pulse proportional to the amplitude of each pulse simultaneously applied to it. With this arrangement the tube will only pass pulses which are of sufficlent amplitude to counter the cutoff bias but not of sufficlent amplitude to cutoff the tube.

Test, L.D.

1958-11-11

403

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

404

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{mu}s) with high repetition rate can be formed by a laser-driven LaB{sub 6} or barium photo-cathode. {copyright} {ital 1997 American Institute of Physics.}

Leung, K. [Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)

1997-02-01

405

Pulsed pyroelectric crystal-powered gamma source  

NASA Astrophysics Data System (ADS)

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 9Be(d,n?)10B. The gamma generator employs an RF-driven inductively coupled plasma ion source to produce deuterium ion current densities up to 2 mA/mm2 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.

2013-04-01

406

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

407

Retrieval of tropospheric column densities of NO2 from combined SCIAMACHY nadir/limb measurements  

NASA Astrophysics Data System (ADS)

The SCIAMACHY instrument onboard the ESA satellite ENVISAT allows the retrieval of column densities of various trace gases, among them NO2. As only instrument of its kind, SCIAMACHY measures in an alternating limb/nadir mode. The limb measurements allow a direct determination of stratospheric column densities, which are needed to extract tropospheric from the total column density measurements performed in (quasi simultaneous) nadir geometry. Here we discuss the potential and limitations of SCIAMACHY limb measurements for estimating stratospheric column densities of NO2 in comparison to a simple reference sector method, and the consequences for the resulting tropospheric column densities. A direct, absolute limb correction scheme improves spatial patterns of tropospheric NO2 column densities at high latitudes compared to the simple reference sector method. However, it results in artificial zonal stripes at low latitudes. Thus, also a relative limb correction scheme was defined, which turned out to successfully reduce stratospheric artefacts in the resulting tropospheric data product without introducing new ones. This relative limb correction scheme is rather simple, robust, and, in essence, based on measurements alone. The effect of the different stratospheric estimation schemes on tropospheric column densities is discussed with respect to zonal and temporal dependencies. In addition, error quantities are defined from the nadir/limb measurements which indicate remaining systematic errors as function of latitude and day. Our new suggested stratospheric estimation scheme, the relative limb correction, improves monthly mean tropospheric slant column densities significantly, e.g. from -1×1015 molec/cm2 (using a simple reference sector method) to ?0 in the Atlantic ocean, and from +1×1015 molec/cm2 to ?0 over Siberia, at 50° N in January.

Beirle, S.; Kühl, S.; Puä·Ä«Te, J.; Wagner, T.

2009-11-01

408

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

409

Characterizing gaseous flow in submicron chromatography columns.  

SciTech Connect

Enormous interest exists to develop the next generation of an integrated microsystem for chemical and biological analysis ({mu}ChemLab{trademark}) and to further reduce the volume of the system. One approach is to scale down the size of critical components and to explore any pumping mechanism that can minimize the power requirement. Since the majority of the pumping requirement is to overcome the wall resistance in the gas chromatography (GC) column, our attention is to study the gas flow in this GC column. As the column dimension decreases, the gaseous flow will go from a continuum regime into a non-continuum regime; i.e., slip, transition, and free molecular regimes. Thus it is very important to well characterize the gaseous flow in submicron columns and to understand its flow behavior. Specifically, in this study, our focus is to investigate the effects of viscosity, rarefaction, and compressibility as the column dimension decreases. Both theoretical predictions and experimental results will be presented.

Wong, Chung-Nin Channy

2003-05-01

410

Extraction of sucrose from molasses  

SciTech Connect

Sucrose is extracted from molasses by passing an aqueous molasses solution over an adsorbent, e.g., calcined Al/sub 2/O/sub 3/-supported pyrolyzed C/sub 6/H/sub 6/. Thus, 10 mL molasses (approximately 46% solids) was run through a column containing 70 cubic centimetres above adsorbent with sucrose retention volume 21.4 and selectivity for sucrose - betaine 23.8.

Landis, A.M.

1982-01-26

411

Miniature electron beam column with a silicon micro field emitter  

SciTech Connect

Silicon micro field emitters (Si-MFEs) are expected to be promising as electron sources for their high brightness and ease in making arrayed microcolumns due to small physical size. We have developed a Si-MFE electron gun assembly that produces an electron beam of 1 keV. All components including the Si acceleration electrode are mounted on an integrated circuit (IC) package stem (TO-8) by anodic and eutectic bonding. A high brightness (75 {mu}A/sr) and a long lifetime ({gt}1000 h) have been observed. To overcome the intrinsic emission instability of Si-MFEs, we developed a simple feedback circuit which controls an extraction voltage. The source position shift and the aberration coefficient change caused by stabilization were evaluated analytically and found to be negligible due to the scaling law as applied to micron size. We confirmed that the total emission fluctuation could be stabilized to less than 1{percent} by detecting the absorption current but also found that this detection should be done in the electron beam column to stabilize the probe current due to the instability of the emission angle. Using the Si-MFE electron gun along with a miniature electron beam column 5 cm in length, we evaluated the electron optical properties and succeeded in demonstrating a scanning electron microscope operation with a resolution less than 0.5 {mu}m. {copyright} {ital 1997 American Vacuum Society.}

Honjo, I.; Endo, Y.; Goto, S. [Fujitsu Laboratories, Ltd., 10-1 Morinosato Wakamiya, Atsugi 243-01 (Japan)

1997-11-01

412

Wrist pulse (image)  

MedlinePLUS

To measure the pulse at the wrist, place the index and middle finger over the underside of the opposite wrist, below the base ... firmly with flat fingers until you feel the pulse in the radial artery.

413

Radial pulse (image)  

MedlinePLUS

... heart. The arteries are the vessels with the "pulse", a rhythmic pushing of the blood in the ... a refilling of the heart chamber. To determine heart rate, one feels the beats at a pulse point ...

414

GAS-LIQUID MASS TRANSFER IN JET BUBBLE COLUMN  

Microsoft Academic Search

The jet bubble column consists of a conical entrance section which expands to a cylindrical column. Gas and liquid are co-currently introduced at the bottom of the column by a small diameter inlet pipe which acts like an ejector. The kinetic energy of the gas and liquid jet together with the conical geometry at the lower section of the column

JOSE A. SALAZAR; KEITH D. WISECARVER; Y. T. SHAH; BRUNO SOLARI

1993-01-01

415

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

416

Pulse Dynamics in Stretched-Pulse Fiber Lasers.  

National Technical Information Service (NTIS)

Stretched pulse additive pulse mode locked fiber lasers use fibers with opposite signs of group velocity dispersion to introduce large changes of pulse width per pass and avoid excessive nonlinearity. We have investigated these intracavity pulse dynamics....

K. Tamura E. P. Ippen H. A. Haus

1995-01-01

417

Pulse compression in plasma: Generation of femtosecond pulses without CPA  

SciTech Connect

Laser pulses can be efficiently compressed to femtosecond duration when a smaller-frequency short pulse collides with high frequency long pulse in rare plasma, absorbing most of its energy. The mechanism of short pulse amplification is nonlinear superradiance.

G. Shvets; N. J. Fisch; A. Pukhov; J. Meyer-ter-Vehn

2000-07-20

418

Electrical pulse generator  

DOEpatents

A technique for generating high-voltage, wide dynamic range, shaped electrical pulses in the nanosecond range. Two transmission lines are coupled together by resistive elements distributed along the length of the lines. The conductance of each coupling resistive element as a function of its position along the line is selected to produce the desired pulse shape in the output line when an easily produced pulse, such as a step function pulse, is applied to the input line.

Norris, Neil J. (Santa Barbara, CA)

1979-01-01

419

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

2011-01-22

420

Physical model studies of water column separation  

NASA Astrophysics Data System (ADS)

Results of physical model studies of water column separation following an upstream valve closure in a horizontal pipe are presented, using three dimensionless parameters: the magnitude of the transient, M, or the ratio between the Joukowsky pressure and the initial absolute head; ?Hr, or the ratio between the maximum overpressure and the Joukowsky pressure, and tcr, the duration of the vapor cavity relative to the pipeline period. Conclusions are derived, aiming to a better understanding of water column separation extreme pressures and to the establishment of useful preliminary design guidelines.

Autrique, R.; Rodal, E.; Sánchez, A.; Carmona, L.

2012-11-01

421

Composite electromagnetic pulse threat  

Microsoft Academic Search

A new electromagnetic pulse threat based on a composite ambient field defined by a combination of lightning, NEMP (nuclear electromagnetic pulse) and microwave threats is discussed. The composite electromagnetic pulse threat has been used to harden a military helicopter. The hardening to a composite threat resulted in the development of simplified hardening verification procedures. It also provided an economical advantage

A. S. Podgorski

1990-01-01

422

Composite electromagnetic pulse threat  

Microsoft Academic Search

A new electromagnetic pulse threat that is based on a composite ambient field defined by a combination of lightning, NEMP (nuclear electromagnetic pulse) and microwave threats is discussed. The composite electromagnetic pulse threat has been used to harden a military helicopter. The hardening to a composite threat resulted in the development of simplified hardening verification procedures. It also provided an

Andrew S. Podgorski

1990-01-01

423

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

2007-08-08

424

Crashworthiness design of multi-corner thin-walled columns  

Microsoft Academic Search

This paper presents a crashworthiness design of regular multi-corner thin-walled columns with different types of cross-sections and different profiles, including straight octagonal columns and curved hexagonal columns. In this paper, the straight octagonal section columns are first optimized, which mainly take axial crash loads during crashes. Next, the curved hexagonal section columns are optimized following the same approach, which are

Yucheng Liu

2008-01-01

425

Performance of FRP-encased steel-concrete composite columns  

Microsoft Academic Search

The thesis summarizes the experimental and analytical results of studies on the behavior of two FRP-encased steel-concrete composite columns under axial loading. Composite columns have been conventionally constructed using steel and concrete. This study utilizes FRP in combination with steel and concrete to manufacture composite columns with enhanced behavior. The first type of column is a concrete-encased steel column wrapped

Kian Karimi

2011-01-01

426

Thermal Integration of a Distillation Column Through Side-Exchangers  

Microsoft Academic Search

Thermal integration of a distillation column with the background process through side exchangers (side reboilers\\/condensers) is important for designing an energy-efficient distillation column. Thermal integration of a distillation column through side exchangers also improves the exergetic efficiency of the column. Invariant rectifying and stripping (IRS) curves are employed for thermodynamic analysis of a distillation column. Different configurations for side-exchanger integration

S. Bandyopadhyay

2007-01-01

427

The refurbished pulse generator.  

PubMed

With the advent of long-life lithium pulse generators, normally functioning pulse generators with a potential life of more than five years have been removed from patients and become available for re-implantation. Although pulse generator refurbishing is widely employed, the practice has not been accepted in the United States. At The Royal Melbourne Hospital, all lithium pulse generators removed because of patient death or other causes were washed in a quaternary ammonium compound and soaked in formaldehyde. Pulse generators were than electronically tested and, if within specification, were made available for re-implantation. Pulse generators were then washed under sterile conditions in distilled water and gas-sterilized with ethylene oxide. Between 1975 and 1978 (48 months), 600 pulse generators were implanted and 93 pulse generators removed. There were 56 deaths, 22 cases of pre-erosion, erosion, or infection and 15 elective removals either due to lead problems or impending power source depletion. Eight-three (89%) pulse generators were refurbished (14% of total implants). This included 12 pulse generators refurbished on two occasions. Ten pulse generators were returned to manufacturers, seven because of impending power source depletion, two with suspected electronic faults, and one with a damaged case. Two complications occurred in patients with refurbished pulse generators. An infective process present with the previous pulse generator spread to a new pocket. The other pulse generator was removed 35 months post second implantation because of impending power source depletion. Primary infection or unusual tissue reactions did not occur. Pulse generator refurbishing as described was found to be a safe and economic procedure. PMID:6160525

Mond, H; Tartaglia, S; Cole, A; Sloman, G

1980-05-01

428

Optimal features combination for pulsed eddy current NDT  

Microsoft Academic Search

This paper investigates current feature extraction techniques for pulsed eddy current NDT including peak value and peak time, spectral characteristics analysis, principal component analysis (PCA) projection coefficient and response shape curvature. Experimental study has been undertaken on samples with artificial surface and subsurface defects and metal thickness changes. Based on a comparative study of the feature extraction techniques, the most

Deqiang Zhou; Gui Yun Tian; Binqiang Zhang; Maxim Morozov; Haitao Wang

2010-01-01

429

Pulse Tube Refrigerators  

NASA Astrophysics Data System (ADS)

Interest in the pulse tube comes from its potential for high reliability and low level of induced vibration. A numerical model has been developed to provide a tool for practical design. It has been successfully validated against the experimental results obtained with a single stage double inlet pulse tube which has achieved a temperature of 28 K at a frequency of a few Hz. Further developments have demonstrated the capability of operating a pulse tube at higher frequencies in association with a Stirling pressure oscillator. Current projects include coaxial geometry for miniature pulse tubes with linear resonant pressure oscillators. A 4K multistaged pulse tube is also in development.

Ravex, A.; Duband, L.; Rolland, P.

1995-10-01

430

HPLC analysis of salinomycin in human plasma using pre-column oxidation and automated heart cut column switching.  

PubMed

Salinomycin is a polyether antibiotic used to promote growth in cattle and poultry. Workers may be exposed to salinomycin through handling of animal feeds that contain the drug and it is necessary to monitor plasma samples from these workers for salinomycin to ensure safety. A method for analysis of salinomycin in plasma samples was therefore developed. Salinomycin and the internal standard narasin are extracted into iso-octane then subjected to silica gel solid-phase extraction in which the sample is washed with methylene chloride-methanol (98.5:15) then eluted with a 90:10 proportion of the same mixture. Both salinomycin and narasin are oxidized with pyridinium dichromate to form a chromophore absorbing at 225 nm. The concentrated product was injected onto a C18 pre-column and heart cut from 1.85 to 3.65 min onto a C18 analytical column. The method was shown to be selective for salinomycin and narasin in six blank plasma samples. The method was linear over a range of 15-300 ng ml-1 with a detection limit of approximately 5 ng ml-1. The mean absolute recovery was found to be 93.4 and 97.9% for salinomycin and narasin, respectively. The method was accurate to within 5% at all concentrations studied. Within-run and between-run precision were both less than 8% RSD at all concentrations studied and the method was suitable for the purpose of monitoring plasma from exposed agricultural workers. PMID:8218527

Karnes, H T; Wei, A T; Dimenna, G P

1993-09-01

431

Influence of pressure on the properties of chromatographic columns II. The column hold-up volume  

SciTech Connect

The effect of the local pressure and of the average column pressure on the hold-up column volume was investigated between 1 and 400 bar, from a theoretical and an experimental point of view. Calculations based upon the elasticity of the solids involved (column wall and packing material) and the compressibility of the liquid phase show that the increase of the column hold-up volume with increasing pressure that is observed is correlated with (in order of decreasing importance): (1) the compressibility of the mobile phase (+1 to 5%); (2) in RPLC, the compressibility of the C{sub 18}-bonded layer on the surface of the silica (+0.5 to 1%); and (3) the expansion of the column tube (< 0.001%). These predictions agree well with the results of experimental measurements that were performed on columns packed with the pure Resolve silica (0% carbon), the derivatized Resolve-C{sub 18} (10% carbon) and the Symmetry-C{sub 18} (20% carbon) adsorbents, using water, methanol, or n-pentane as the mobile phase. These solvents have different compressibilities. However, 1% of the relative increase of the column hold-up volume that was observed when the pressure was raised is not accounted for by the compressibilities of either the solvent or the C{sub 18}-bonded phase. It is due to the influence of the pressure on the retention behavior of thiourea, the compound used as tracer to measure the hold-up volume.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Martin, Michel [Ecole Superieure de Physique et de Chimie Industrielles; Guiochon, Georges A [ORNL

2005-03-01

432

Influence of pressure on the properties of chromatographic columns II. The column hold-up volume  

SciTech Connect

The effect of the local pressure and of the average column pressure on the hold-up column volume was investigated between 1 and 400 bar, from a theoretical and an experimental point of view. Calculations based upon the elasticity of the solids involved (column wall and packing material) and the compressibility of the liquid phase show that the increase of the column hold-up volume with increasing pressure that is observed is correlated with (in order of decreasing importance): (1) the compressibility of the mobile phase (+1 to 5%); (2) in RPLC, the compressibility of the C{sub 18}-bonded layer on the surface of the silica (+0.5 to 1%); and (3) the expansion of the column tube (< 0.001%). These predictions agree well with the results of experimental measurements that were performed on columns packed with the pure Resolve silica (0% carbon), the derivatized Resolve-C{sub 18} (10% carbon) and the Symmetry-C{sub 18} (20% carbon) adsorbents, using water, methanol, or n-pentane as the mobile phase. These solvents have different compressibilities. However, 1% of the relative increase of the column hold-up volume that was observed when the pressure was raised is not accounted for by the compressibilities of either the solvent or the C{sub 18}-bonded phase. It is due to the influence of the pressure on the retention behavior of thiourea, the compound used as tracer to measure the hold-up volume.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Martin, Michel [Ecole Superieure de Physique et de Chimie Industrielles; Guiochon, Georges A [ORNL

2005-04-01

433

Optimal design of complex azeotropic distillation columns  

Microsoft Academic Search

Geometric methods are valuable tools for process synthesis and design since they provide designers with intuition and quantitative results. The calculation and graphical representation of azeotropes, residue curves and distillation boundaries provide a wealth of knowledge about the entire composition space. This paper shows how these tools can be used for optimal design of complex azeotropic distillation columns. Two examples

Stanislaw K Wasylkiewicz; Leo C Kobylka; Francisco J. L Castillo

2000-01-01

434

Carbon Column Operation in Waste Water Treatment.  

National Technical Information Service (NTIS)

The Adsorption and filtration of waste water in an isothermal column of granular activated carbon has been mathematically modeled. Based on this model, a simulation program was prepared and coded in Fortran IV to be run on the IBM 360/50 level G compiler....

C. Vanier C. Tien

1970-01-01

435

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 ...

436

Column Liquid Chromatography in Polymer Degradation Studies  

Microsoft Academic Search

Column liquid chromatography performed on polymer samples subjected to degradation reactions makes up an important source of information for determining the polymer degradation mechanisms. In the present paper it is shown how molecular weight distribution changes and formation of new compounds due to degradation reactions can be conveniently analyzed by size exclusion and adsorption\\/partition chromatography. The sensitivity and uniqueness of

Oscar Chiantore

1990-01-01

437

Improve distillation-column control design  

SciTech Connect

Steady-state process models have long been used to assist the engineer in designing control strategies for distillation columns. Yet, a large number of industrial columns still operate in manual or with ineffectual controls. So, better control design techniques using steady-state models certainly are needed. In this article, the authors introduced an improved method that already has proven itself on 33 industrial columns. This article deals exclusively with the design of single-point composition controls. The vast majority of columns have one-sided composition specifications. With such specifications, a single-point composition control scheme can keep both top and bottom product compositions at or below limits for a wide range of disturbances. The predominance of one-sided specifications means that the main incentive for dual-point control schemes is achieving energy savings. In most cases, though, the energy savings are small and do not justify the added difficulty of implementing and maintaining dual-point control. Additionally, dual-point schemes often have significantly longer recoveries from upsets due to interactions between the control loops. The design procedure can be best thought of as a general approach rather than a single detailed procedure that covers all cases. The produce must be adapted to each problem because there are many different types of distillation and almost every industrial problem has some unique requirement.

Fruehauf, P.S.; Mahoney, D.P.

1994-03-01

438

The Energy-Absorbing Steering Column.  

National Technical Information Service (NTIS)

A previous four-year study of fatal automobile accidents has shown that the steering assembly-the column and steering wheel rim--ranked high as one of the major causes of fatzal and serious injuries to drivers in automobile crashes. These studies indicate...

D. F. Huelke W. A. Chewning

1968-01-01

439

Selective detachment process in column flotation froth  

Microsoft Academic Search

The selectivity in flotation columns involving the separation of particles of varying degrees of floatability is based on differential flotation rates in the collection zone, reflux action between the froth and collection zones, and differential detachment rates in the froth zone. Using well-known theoretical models describing the separation process and experimental data, froth zone and overall flotation recovery values were

Rick Q. Honaker; Ahmet V. Ozsever; B. K. Parekh

2006-01-01

440

ACM SIGACT news distributed computing column 11  

Microsoft Academic Search

The Distributed Computing Column covers the theory of systems that are composed of a number of interacting computing elements. These include problems of communication and networking, databases, distributed shared memory, multiprocessor architectures, operating systems, verification, internet, and the web.This issue consists of the paper \\

Sergio Rajsbaum

2003-01-01

441

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

442

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

443

Thermal Analysis of LANL Ion Exchange Column.  

National Technical Information Service (NTIS)

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 ...

J. E. Laurinat

1999-01-01

444

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

445

Gas flow distribution in packed columns  

Microsoft Academic Search

The distribution of gas flow over the cross section of packed columns depends on the manner of gas flow feeding, on packing type, packing arrangement, and internal devices in the apparatus body. Various types of gas inlet devices are studied in order to estimate their ability for creation of uniform velocity profiles. The gas flow uniformity is characterized by the

Rumen Darakchiev; Chavdar Dodev

2002-01-01

446

Simulation and control of reactive distillation column  

Microsoft Academic Search

The paper discusses about the application of PID controller and fuzzy controller in reactive distillation column. A generic mathematical model of reactive distillation has been taken for simulation. The PID and fuzzy controllers are designed for the process and then the overall process is controlled by using conventional (PID) and intelligent (fuzzy) controllers separately. Conventional PID controller is used to

Ujjwal Kapoor; Asha Rani; Vijander Singh; J. R. P Gupta

2011-01-01

447

Unique concrete column offloads marine crude  

SciTech Connect

This paper describes the world's first buoyant articulated loading column (ALC) made principally of concrete and which can operate in the weather conditions of the North Sea. The ALC is an unmanned structure, mooring and loading being controlled by a tanker. Gravity base buoyancy tanks ''floaters'' are lightly reinforced and have a similar section to the column, 29.5 ft diameter and a wall thickness of 13.8 in. Before towing to the field, the column was ballasted by 1,000 metric tons of hematite, a fine ore aggregate. Final ballast will comprise 1,000 metric tons of hematite and 460 metric tons of water. Setting will be carried out by pumping water into the column until the base structure contacts the seabed. Once the base has touched down, the 2 cyclindrical buoyancy tanks will be vented, thus instantly applying the full weight of the gravity base to the sea floor and anchoring the ALC. Hyperbaric welding techniques will be used to tie the subsea pipeline into the expansion loop.

Myrabo, D.O.

1982-10-01

448

Constrained Optimal Design of Columns Against Buckling  

Microsoft Academic Search

The buckling loads of straight, simply supported columns, loaded by axial thrust are maximized, subject to the restriction that the available volume of structural material is specified. In addition, a constraint is placed upon the maximum allowable prebuckling stress. Analytic solutions are presented for a variety of different cross-sectional geometries.

JAMES C. FRAUENTHAL

1972-01-01

449

Heat Integration in Batch Distillation Column  

NASA Astrophysics Data System (ADS)

A new heat integrated batch distillation column has been configured in this paper. Here the column and reboiler are connected in an annular arrangement and a compressor is positioned between them to maintain the pressure difference. The heat integration is between the rectifying batch column and one concentric reboiler. Ethanol-Water binary system is chosen as an example for the design and analysis of this heat integrated batch distillation column (HIBDiC). In this work, a sensitivity test for selecting the optimal value of the total number of trays and reboiler duty and a thermodynamic feasibility test for its design acceptability has been accomplished. The principal objective of this study is to investigate the influence of compression ratio (CR) on the energy consumption of distillation and to find out the optimal value of CR. Also a comparative analysis of HIBiDC on energy consumption in steady state as well as in dynamic state has been carried out on the basis of its conventional model. The proposed scheme is capable to save the energy up to 50.52% compared to its conventional one by selecting the CR of 1.4 as an optimal value.

Maiti, Debadrita; Jana, Amiya K.; Samanta, Amar Nath

2010-10-01

450

Lattice approaches to packed column simulations  

Microsoft Academic Search

This work presents a review of the findings into the ability of a digitally based particle packing algorithm, called DigiPac, to predict bed structure in a variety of packed columns, for a range of generic pellet shapes frequently used in the chemical and process engineering industries. Resulting macroscopic properties are compared with experimental data derived from both invasive and non-destructive

Richard Caulkin; Xiaodong Jia; Mike Fairweather; Richard A. Williams

2008-01-01

451

Isolation of lactoperoxidase using different cation exchange resins by batch and column procedures.  

PubMed

Lactoperoxidase (LP) was isolated from whey protein by cation-exchange using Carboxymethyl resin (CM-25C) and Sulphopropyl Toyopearl resin (SP-650C). Both batch and column procedures were employed and the adsorption capacities and extraction efficiencies were compared. The resin bed volume to whey volume ratios were 0.96:1.0 for CM-25C and 0.64:1.0 for SP-650 indicating higher adsorption capacity of SP-650 compared with CM-25C. The effluent LP activity depended on both the enzyme activity in the whey and the amount of whey loaded on the column within the saturation limits of the resin. The percentage recovery was high below the saturation point and fell off rapidly with over-saturation. While effective recovery was achieved with column extraction procedures, the recovery was poor in batch procedures. The whey-resin contact time had little impact on the enzyme adsorption. SDS PAGE and HPLC analyses were also carried out, the purity was examined and the proteins characterised in terms of molecular weights. Reversed phase HPLC provided clear distinction of the LP and lactoferrin (LF) peaks. The enzyme purity was higher in column effluents compared with batch effluents, judged on the basis of the clarity of the gel bands and the resolved peaks in HPLC chromatograms. PMID:20576170

Fweja, Leonard Wt; Lewis, Michael J; Grandison, Alistair S

2010-08-01

452

Urine iodide determination by ion-pair reversed-phase high performance liquid chromatography and pulsed amperometric detection.  

PubMed

A sensitive and specific ion-pair reversed-phase high performance liquid chromatography (HPLC) method for urinary iodine analysis is described. This method is based on pulsed amperometric detection (PAD) using a silver working electrode (HPLC-PAD), which improves peak shape, electrode stability as well as linearity and reproducibility. A two-step extraction process consisting of solid phase extraction (SPE) and liquid-liquid extraction with dichloromethane was added in order to improve sample purification which is essential with the use of PAD. Treated samples were eluted on a C18 column, using a phosphate buffer containing ion-pairing reagent tetrabutylammonium and 5% MeOH. The calibration standard curves were linear up to 500 ?g/L and within-run and between-run coefficients of variation (CVs) were <6% with the quantification limit fixed at 6 ?g/L. Accuracy, expressed as recovery, ranged from 94% to 104%. Comparison with the Technicon AutoAnalyzer acid digestion (AA) method resulted in a high correlation (r=0.9916). Due to a low quantification limit and high sample throughput, the proposed technique appears suitable for both epidemiological and clinical follow-up studies. PMID:22967590

Nguyen, Vo Thanh Phuong; Piersoel, Virginie; El Mahi, Tarik

2012-06-27

453

Effect of the column length on the characteristics of the packed bed and the column efficiency in a dynamic axial compression column  

Microsoft Academic Search

The axial homogeneity of preparative-scale chromatography columns was studied by measuring the overall properties of similar columns differing only by their lengths. The properties investigated were the packing density, the external porosity, the permeability and the column efficiency. Two different materials were used, one made of large, irregular silica particles compressed under either a high or a low degree of

Joon-Ho Koh; Georges Guiochon

1998-01-01

454

Arc discharge efficiency of a multi-megawatt long pulse ion source for the KSTAR neutral beam injector  

NASA Astrophysics Data System (ADS)

A multi-megawatt long pulse ion source (LPIS) was developed for the Korea Superconducting Tokamak Advanced Research (KSTAR) neutral beam (NB) injector. Arc discharge characteristics of the ion source were investigated on the NB test stand. The ion source consists of a magnetic bucket plasma generator with multi-pole cusp fields and a set of tetrode accelerators with circular apertures. The inner volume of the ion source, including the accelerator column, is approximately 150 litres. Design requirements for the ion source were a 120 kV/65 A deuterium beam and a 300 s pulse length and initially an 80 kV/48 A hydrogen beam for a 20 s pulse length. Arc discharges of the plasma generator with hydrogen gases have been controlled by the emission-limited mode, operated by the applied heating voltage of the cathode filaments. Stable and efficient arc plasmas, with a maximum arc power of 110 kW, have been produced by a constant voltage (CV) mode operation of an arc power supply. The CV mode operation of the arc powers was more efficient than the constant power (CP) mode operation in the LPIS. A maximum ion density of 9.1 × 1011 cm-3 was measured by using electrostatic probes. The plasma non-uniformity of the ion source was less than 8% and was under the design limit. An optimum arc efficiency, defined by the ratio of extractible ion beam current to arc input power, of 0.46 A kW-1 was estimated for the CV mode operation and 0.44 A kW-1 for the CP mode operation. This arc efficiency is enough to extract the expected hydrogen beam of 48 A.

Chang, Doo-Hee; Jeong, Seung-Ho; Oh, Byung-Hoon; Lee, Kwang-Won; Seo, Chang-Seog

2005-05-01

455

Scaling up of high-speed countercurrent chromatographic apparatus with three columns connected in series for rapid preparation of (-)-epicatechin.  

PubMed

In the present study, compact high-speed countercurrent chromatographic apparatus was constructed with three columns connected in series. Two sets of columns were prepared from 10 mm and 12 mm I.D. tubing to form 12 L and 15 L capacities, respectively. Performance of these columns was compared for the separation of (-)-epicatechin gallate (ECG) from a tea extract by flash countercurrent chromatography (FCCC). In each separation, 200 g of the tea extract in 1600 mL of mobile phase was loaded onto the column. The 12 L column gave 7.5 L (35 g of ECG) and the 15 L column gave 9 L (40 g of ECG) of ECG solution without impurities. The ECG solution was directly hydrolyzed by tannase into (-)-epicatechin. The hydrolysate was purified by flash chromatography on AB-8 macroporous resin to give 52 g of EC (purity 99.1%). This scaled up apparatus could be used for the industrial separation of natural products. PMID:23219478

Du, Qingbao; Jiang, Heyuan; Yin, Junfeng; Xu, Yongquan; Du, Wenkai; Li, Bo; Du, Qizhen

2012-11-19

456

DNAPL transport through macroporous, clayey till columns  

SciTech Connect

This paper provides the first experimental determination of the rates and distribution of transport of a dense, nonaqueous phase liquid (DNAPL) through a naturally bioporous and fractured clayey till deposit. Until now, assessment of DNAPL behavior in this type of deposit has relied on theoretical studies. Predictions of DNAPL transport have proven to be uncertain as a result of difficulties in measuring critical parameters such as DNAPL entry pressure and flow behavior in response to natural fracture/biopore apertures and the degree of interconnection of these structures. In the present investigation, the migration of free product trichloroethylene (TCE) was studied by means of two undisturbed clayey till columns under in situ effective soil stress conditions. The experiments revealed that transport of TCE was restricted to biopores in one column and fractures in another column, bypassing the low-permeability clayey matrix. Effective porosities of the columns, i.e., biopores and fractures, were two to three orders of magnitude lower than total porosities, i.e., macropores and matrix. Single phase water flow rates through the columns at water-saturated conditions followed a linear relationship with hydraulic gradient. TCE flow could not be predicted from the single-phase calculations because of nonlinearity observed between applied TCE injection heads and resulting TCE flow. TCE flow rates were 24 and 10.3 m/day at TCE gradients of 1.18 and 0.91, respectively. The observed flow rates indicate that in cases where vertical biopores or fractures fully penetrate clayey till aquitards, a low-viscosity DNAPL may quickly enter underlying aquifers. The experiments further indicate that 100 liters of a low-viscosity DNAPL are sufficient to contaminate approximately 25 to 100 m{sup 3} of till material because of the small effective porosity constituted by the biopores and fractures.

Joergensen, P.R. [Univ. of Copenhagen (Denmark). Geological Inst.]|[Danish Geotechnical Inst., Lyngby (Denmark); Broholm, K.; Sonnenborg, T.O.; Arvin, E. [Technical Univ. of Denmark, Lyngby (Denmark)

1998-07-01

457

All-optical histology using ultrashort laser pulses.  

PubMed

As a means to automate the three-dimensional histological analysis of brain tissue, we demonstrate the use of femtosecond laser pulses to iteratively cut and image fixed as well as fresh tissue. Cuts are accomplished with 1 to 10 microJ pulses to ablate tissue with micron precision. We show that the permeability, immunoreactivity, and optical clarity of the tissue is retained after pulsed laser cutting. Further, samples from transgenic mice that express fluorescent proteins retained their fluorescence to within microns of the cut surface. Imaging of exogenous or endogenous fluorescent labels down to 100 microm or more below the cut surface is accomplished with 0.1 to 1 nJ pulses and conventional two-photon laser scanning microscopy. In one example, labeled projection neurons within the full extent of a neocortical column were visualized with micron resolution. In a second example, the microvasculature within a block of neocortex was measured and reconstructed with micron resolution. PMID:12848930

Tsai, Philbert S; Friedman, Beth; Ifarraguerri, Agustin I; Thompson, Beverly D; Lev-Ram, Varda; Schaffer, Chris B; Xiong, Qing; Tsien, Roger Y; Squier, Jeffrey A; Kleinfeld, David

2003-07-01

458

Nanosecond length electron pulses from a laser-excited photocathode  

SciTech Connect

A photocathode made from polycrystalline lanthanum hexaboride (LaB{sub 6}) has produced nanosecond length electron pulses when excited by an excimer laser at 308nm. Peak currents in excess of 1A have been observed, with quantum yields of 4 {times} 10{sup {minus}5} being measured. A method for extracting the electrons from an emission-limited cathode, plasma extraction, has been demonstrated. This technique uses a low power continuous discharge to provide the electric field needed to extract the photoelectrons. This technique may be useful in producing high repetition rate short pulse ion sources. 10 refs., 4 figs.

Young, A.T.; D'Etat, B.; Stutzin, G.C.; Leung, K.N.; Kunkel, W.B.

1989-06-01

459

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

460

Transverse bacterial migration induced by chemotaxis in a packed column with structured physical heterogeneity.  

PubMed

The significance of chemotaxis in directing bacterial migration toward contaminants in natural porous media was investigated under groundwater flow conditions. A laboratory-scale column, with a coarse-grained sand core surrounded by a fine-grained annulus, was used to simulate natural aquifers with strata of different hydraulic conductivities. A chemoattractant source was placed along the central axis of the column to model contaminants trapped in the heterogeneous subsurface. Chemotactic bacterial strains, Escherichia coli HCB1 and Pseudomonas putida F1, introduced into the column by a pulse injection, were found to alter their transport behaviors under the influence of the attractant chemical emanating from the central source. For E. coil HCB1, approximately 18% more of the total population relative to the control without attractant exited the column from the coarse sand layer due to the chemotactic effects of alpha-methylaspartate under an average fluid velocity of 5.1 m/d. Although P. putida F1 demonstrated no observable changes in migration pathways with the model contaminant acetate under the same flow rate, when the flow rate was reduced to 1.9 m/d, approximately 6-10% of the population relative to the control migrated from the fine sand layer toward attractant into the coarse sand layer. Microbial transport properties were further quantified by a mathematical model to examine the significance of bacterial motility and chemotaxis under different hydrodynamic conditions, which suggested important considerations for strain selection and practical operation of bioremediation schemes. PMID:19731698

Wang, Meng; Ford, Roseanne M

2009-08-01

461

Transverse bacterial migration induced by chemotaxis in a packed column with structured physical heterogeneity  

PubMed Central

The significance of chemotaxis in directing bacterial migration towards contaminants in natural porous media was investigated under groundwater flow conditions. A laboratory-scale column, with a coarse-grained sand core surrounded by a fine-grained annulus, was used to simulate natural aquifers with strata of different hydraulic conductivities. A chemoattractant source was placed along the central axis of the column to model contaminants trapped in the heterogeneous subsurface. Chemotactic bacterial strains, Escherichia coli HCB1 and Pseudomonas putida F1, introduced into the column by a pulse injection, were found to alter their transport behaviors under the influence of the attractant chemical emanating from the central source. For E. coli HCB1, approximately 18% more of the total population relative to the control without attractant exited the column from the coarse sand layer due to the chemotactic effects of ?-methylaspartate under an average fluid velocity of 5.1 m/d. Although P. putida F1 demonstrated no observable changes in migration pathways with the model contaminant acetate under the same flow rate, when the flow rate was reduced to 1.9 m/d, approximately 6~10% of the population relative to the control migrated from the fine sand layer towards attractant into the coarse sand layer. Microbial transport properties were further quantified by a mathematical model to examine the significance of bacterial motility and chemotaxis under different hydrodynamic conditions, which suggested important considerations for strain selection and practical operation of bioremediation schemes.

Wang, Meng; Ford, Roseanne M.

2009-01-01

462

Short pulse phenomena produced with long pulses  

NASA Astrophysics Data System (ADS)

We have found a way to produce to phenomena usually associated with ultrashort laser pulses using surprisingly long pulses. For example, the spatial asymmetry of a dissociating molecule has been observed to vary with the CEP for very short intense pulses [1-3]. By using chirped pulses with large bandwidths, however, our calculations show large, CEP-dependent asymmetry in dissociating H2^+ even for 100 fs long pulses. This effect is also shown in the spatial asymmetry of an ionized atomic target. We also find varying the bandwidth and the direction of the chirp of the pulse can affect another multi-photon process, zero-photon dissociation of H2^+ [4]. While it is not obvious how these unexpected phenomena can be explained in the usual time-dependent, field-based picture, their explanation in terms of a photon picture is rather straightforward, underscoring its utility even in the strong field regime. [1] M. F. Kling et al., Science 312, 246 (2006). [2] M. Kremer et al., Phys. Rev. Lett. 103, 213003 (2009). [3] V. Roudnev, B. D. Esry, and I. Ben-Itzhak, Phys. Rev. Lett. 93, 163601 (2004). [4] J. H. Posthumus et al. J. Phys. B: At. Mol. Opt. Phys. 28, 623 (2004).

Hernández, J. V.; Esry, B. D.

2011-06-01

463