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1

Zonal Rate Model for Axial and Radial Flow Membrane Chromatography. Part I: Knowledge Transfer Across Operating Conditions and Scales  

PubMed Central

The zonal rate model (ZRM) has previously been applied for analyzing the performance of axial flow membrane chromatography capsules by independently determining the impacts of flow and binding related non-idealities on measured breakthrough curves. In the present study, the ZRM is extended to radial flow configurations, which are commonly used at larger scales. The axial flow XT5 capsule and the radial flow XT140 capsule from Pall are rigorously analyzed under binding and non-binding conditions with bovine serum albumin (BSA) as test molecule. The binding data of this molecule is much better reproduced by the spreading model, which hypothesizes different binding orientations, than by the well-known Langmuir model. Moreover, a revised cleaning protocol with NaCl instead of NaOH and minimizing the storage time has been identified as most critical for quantitatively reproducing the measured breakthrough curves. The internal geometry of both capsules is visualized by magnetic resonance imaging (MRI). The flow in the external hold-up volumes of the XT140 capsule was found to be more homogeneous as in the previously studied XT5 capsule. An attempt for model-based scale-up was apparently impeded by irregular pleat structures in the used XT140 capsule, which might lead to local variations in the linear velocity through the membrane stack. However, the presented approach is universal and can be applied to different capsules. The ZRM is shown to potentially help save valuable material and time, as the experiments required for model calibration are much cheaper than the predicted large-scale experiment at binding conditions. Biotechnol. Bioeng. 2013; 110: 1129–1141. © 2012 Wiley Periodicals, Inc. PMID:23097218

Ghosh, Pranay; Vahedipour, Kaveh; Lin, Min; Vogel, Jens H; Haynes, Charles A; von Lieres, Eric

2013-01-01

2

Radial Flows in Supergranules  

NASA Technical Reports Server (NTRS)

We determine the radial component of the supergranular flow velocity by examining the center-to-limb variation of the Doppler velocity signal. We acquire individual Doppler images obtained with the MDI instrument on the SOHO spacecraft and process them to remove the p-mode oscillation signal, the axisymmetric flows, the convective blueshift signal, and instrumental artifacts. The remaining Doppler signal contains only cellular flow structures. The Doppler signal from the horizontal flows in these cells varies like sin p, where p is the heliocentric angle from disk center. The Doppler signal from radial flows varies like cos p. We fit the center-to-limb variation of the mean squared velocity signal to a straight line in sin(exp 2) rho over the central portion of the disk. The intercept of this line at disk center gives the amplitude of the radial component of the flow. The slope of the line gives the amplitude of the horizontal component. We find that the radial flows for typical supergranules have speeds about 10% that of their associated horizontal flows or about 30 m/s. The ratio of the radial to horizontal flow speed increases from 9% to about 18% as the size of the cells decreases from > 60 Mm to approximately 5 Mm. We use data simulations to check these results and find a ratio that increases from 5% to only about 12% over the same range of cell sizes. These smaller ratios are attributed to an underestimation of the horizontal flow speeds due to the fact that, the transverse component of the horizontal flow is not detected by the Doppler measurements.

Hathaway, D. H.; Beck, J. G.; Han, S.; Raymond, J.; Rose, M. Franklin (Technical Monitor)

2000-01-01

3

Computational fluid dynamic simulation of axial and radial flow membrane chromatography: mechanisms of non-ideality and validation of the zonal rate model.  

PubMed

Membrane chromatography (MC) is increasingly being used as a purification platform for large biomolecules due to higher operational flow rates. The zonal rate model (ZRM) has previously been applied to accurately characterize the hydrodynamic behavior in commercial MC capsules at different configurations and scales. Explorations of capsule size, geometry and operating conditions using the model and experiment were used to identify possible causes of inhomogeneous flow and their contributions to band broadening. In the present study, the hydrodynamics within membrane chromatography capsules are more rigorously investigated by computational fluid dynamics (CFD). The CFD models are defined according to precisely measured capsule geometries in order to avoid the estimation of geometry related model parameters. In addition to validating the assumptions and hypotheses regarding non-ideal flow mechanisms encoded in the ZRM, we show that CFD simulations can be used to mechanistically understand and predict non-binding breakthrough curves without need for estimation of any parameters. When applied to a small-scale axial flow MC capsules, CFD simulations identify non-ideal flows in the distribution (hold-up) volumes upstream and downstream of the membrane stack as the major source of band broadening. For the large-scale radial flow capsule, the CFD model quantitatively predicts breakthrough data using binding parameters independently determined using the small-scale axial flow capsule, identifying structural irregularities within the membrane pleats as an important source of band broadening. The modeling and parameter determination scheme described here therefore facilitates a holistic mechanistic-based method for model based scale-up, obviating the need of performing expensive large-scale experiments under binding conditions. As the CFD model described provides a rich mechanistic analysis of membrane chromatography systems and the ability to explore operational space, but requires detailed knowledge of internal capsule geometries and has much greater computational requirements, it is complementary to the previously described strengths and uses of the ZRM for process analysis and design. PMID:23885666

Ghosh, Pranay; Vahedipour, Kaveh; Lin, Min; Vogel, Jens H; Haynes, Charles; von Lieres, Eric

2013-08-30

4

Radial flow heat exchanger  

DOEpatents

A radial flow heat exchanger (20) having a plurality of first passages (24) for transporting a first fluid (25) and a plurality of second passages (26) for transporting a second fluid (27). The first and second passages are arranged in stacked, alternating relationship, are separated from one another by relatively thin plates (30) and (32), and surround a central axis (22). The thickness of the first and second passages are selected so that the first and second fluids, respectively, are transported with laminar flow through the passages. To enhance thermal energy transfer between first and second passages, the latter are arranged so each first passage is in thermal communication with an associated second passage along substantially its entire length, and vice versa with respect to the second passages. The heat exchangers may be stacked to achieve a modular heat exchange assembly (300). Certain heat exchangers in the assembly may be designed slightly differently than other heat exchangers to address changes in fluid properties during transport through the heat exchanger, so as to enhance overall thermal effectiveness of the assembly.

Valenzuela, Javier (Hanover, NH)

2001-01-01

5

Radial flow nuclear thermal rocket (RFNTR)  

DOEpatents

A radial flow nuclear thermal rocket fuel assembly includes a substantially conical fuel element having an inlet side and an outlet side. An annular channel is disposed in the element for receiving a nuclear propellant, and a second, conical, channel is disposed in the element for discharging the propellant. The first channel is located radially outward from the second channel, and separated from the second channel by an annular fuel bed volume. This fuel bed volume can include a packed bed of loose fuel beads confined by a cold porous inlet frit and a hot porous exit frit. The loose fuel beads include ZrC coated ZrC-UC beads. In this manner, nuclear propellant enters the fuel assembly axially into the first channel at the inlet side of the element, flows axially across the fuel bed volume, and is discharged from the assembly by flowing radially outward from the second channel at the outlet side of the element.

Leyse, Carl F. (Idaho Falls, ID)

1995-01-01

6

Fast Radial Flows in Transition Disk Holes  

NASA Astrophysics Data System (ADS)

Protoplanetary "transition" disks have large, mass-depleted central cavities, yet also deliver gas onto their host stars at rates comparable to disks without holes. The paradox of simultaneous transparency and accretion can be explained if gas flows inward at much higher radial speeds inside the cavity than outside the cavity, since surface density (and by extension optical depth) varies inversely with inflow velocity at fixed accretion rate. Radial speeds within the cavity might even have to approach free-fall values to explain the huge surface density contrasts inferred for transition disks. We identify observational diagnostics of fast radial inflow in channel maps made in optically thick spectral lines. Signatures include (1) twisted isophotes in maps made at low systemic velocities and (2) rotation of structures observed between maps made in high-velocity line wings. As a test case, we apply our new diagnostic tools to archival Atacama Large Millimeter Array data on the transition disk HD 142527 and uncover evidence for free-fall radial velocities inside its cavity. Although the observed kinematics are also consistent with a disk warp, the radial inflow scenario is preferred because it predicts low surface densities that appear consistent with recent observations of optically thin CO isotopologues in this disk. How material in the disk cavity sheds its angular momentum wholesale to fall freely onto the star is an unsolved problem; gravitational torques exerted by giant planets or brown dwarfs are briefly discussed as a candidate mechanism.

Rosenfeld, Katherine A.; Chiang, Eugene; Andrews, Sean M.

2014-02-01

7

Radial Chromatography for the Separation of Nitroaniline Isomers  

ERIC Educational Resources Information Center

Separation techniques are usually presented in the undergraduate organic laboratory to teach students how to purify and isolate compounds. Often the concept of liquid chromatography is introduced by having students create "silica gel columns" to separate components of a reaction mixture. Although useful, column chromatography can be a laborious…

Miller, Robert B.; Case, William S.

2011-01-01

8

Sugar Determination in Foods with a Radially Compressed High Performance Liquid Chromatography Column.  

ERIC Educational Resources Information Center

Advocates use of Waters Associates Radial Compression Separation System for high performance liquid chromatography. Discusses instrumentation and reagents, outlining procedure for analyzing various foods and discussing typical student data. Points out potential problems due to impurities and pump seal life. Suggests use of ribose as internal…

Ondrus, Martin G.; And Others

1983-01-01

9

Zonal flows in stellarators in an ambient radial electric field  

SciTech Connect

The linear dynamics of zonal flows is addressed in stellarator geometry in the presence of an ambient (neoclassical) radial electric field. Global gyrokinetic particle-in-cell simulations are used to study the properties of the residual flow and its dependence on the plasma parameters and magnetic geometry. Properties of the zonal flow are compared in different magnetic geometries.

Mishchenko, Alexey; Kleiber, Ralf [Max-Planck-Institut fuer Plasmaphysik, EURATOM-Association, D-17491 Greifswald (Germany)

2012-07-15

10

Turbulent flow chromatography in bioanalysis: a review.  

PubMed

With advances in fast chromatography techniques, and highly sensitive and selective detection methods such as tandem mass spectrometry, very high-throughput bioanalytical methods can now be easily developed. The bottleneck of the analytical process then becomes the sample preparation, which it is now realized is crucial to the robust operation of the analytical system, especially for quantitative assays. Turbulent flow liquid chromatography was developed in the late 1990s, and combines 'size exclusion' and traditional stationary phase column chemistry to separate macromolecules, such as proteins, from smaller molecules and analytes of interest in biological fluids. By definition, the process is very rapid, and the instrumentation and software have been developed for fully automated, on-line extraction of neat biological fluids. This work aims to review the chromatographic theory of turbulent flow chromatography and illustrate, using examples from recent literature, the application of this technique to a range of analytes from a number of different biological matrices. PMID:22733585

Couchman, Lewis

2012-08-01

11

Dynamics of a vortex pair in radial flow  

SciTech Connect

The problem of vortex pair motion in two-dimensional radial flow is solved. Under certain conditions for flow parameters, the vortex pair can reverse its motion within a bounded region. The vortex-pair translational velocity decreases or increases after passing through the source/sink region, depending on whether the flow is diverging or converging, respectively. The rotational motion of a corotating vortex pair in a quiescent environment transforms into motion along a logarithmic spiral in radial flow. The problem may have applications in astrophysics and geophysics.

Bannikova, E. Yu., E-mail: bannikova@astron.kharkov.ua; Kontorovich, V. M. [National Academy of Sciences of Ukraine, Institute of Radio Astronomy (Ukraine)], E-mail: vkont@ira.kharkov.ua; Reznik, G. M. [Russian Academy of Sciences, Shirshov Institute of Oceanology (Russian Federation)], E-mail: greznik11@yahoo.com

2007-10-15

12

Non-radial flow in the solar wind  

NASA Technical Reports Server (NTRS)

Although the radial component of the solar wind dominates the solar wind speed, significant non-radial velocity components are also present. These flows are more difficult to measure accurately, but we now have data sets including the east-west (tangential) and north-south (normal) flows from PVO at Venus, IMP 8 at Earth, and Voyagers 1 and 2 from 1 to 45 AU. We compare the non-radial flow observations from these spacecraft. One of the more interesting features is that the north-south flow angle observed at Earth and Venus oscillates with the period of a local (Earth or Venus) year. These oscillations occur throughout two solar cycles in the IMP 8 data set and are very apparent in the PVO data from 1978 to 1986 but less obvious after this. We will report on the origin of this feature. The tangential flow observed by both IMP 8 and Voyager is on average slightly positive (approximately 1.75 km/s). The magnitudes of the nonradial velocity components decrease with distance from the Sun.

Richardson, J. D.; Paularena, K. I.; Gazis, P. R.

1995-01-01

13

Radial accretion flows on static spherically symmetric black holes  

E-print Network

We analyze the steady radial accretion of matter into a nonrotating black hole. Neglecting the self-gravity of the accreting matter, we consider a rather general class of static, spherically symmetric and asymptotically flat background spacetimes with a regular horizon. In addition to the Schwarzschild metric, this class contains certain deformation of it which could arise in alternative gravity theories or from solutions of the classical Einstein equations in the presence of external matter fields. Modeling the ambient matter surrounding the black hole by a relativistic perfect fluid, we reformulate the accretion problem as a dynamical system, and under rather general assumptions on the fluid equation of state, we determine the local and global qualitative behavior of its phase flow. Based on our analysis and generalizing previous work by Michel, we prove that for any given positive particle density number at infinity, there exists a unique radial, steady-state accretion flow which is regular at the horizon....

Chaverra, Eliana

2015-01-01

14

Multiphase flow modeling in centrifugal partition chromatography.  

PubMed

The separation efficiency in Centrifugal Partition Chromatography (CPC) depends on selection of a suitable biphasic solvent system (distribution ratio, selectivity factor, sample solubility) and is influenced by hydrodynamics in the chambers. Especially the stationary phase retention, the interfacial area for mass transfer and the flow pattern (backmixing) are important parameters. Their relationship with physical properties, operating parameters and chamber geometry is not completely understood and predictions are hardly possible. Experimental flow visualization is expensive and two-dimensional only. Therefore we simulated the flow pattern using a volume-of-fluid (VOF) method, which was implemented in OpenFOAM®. For the three-dimensional simulation of a rotating FCPC®-chamber, gravitational centrifugal and Coriolis forces were added to the conservation equation. For experimental validation the flow pattern of different solvent systems was visualized with an optical measurement system. The amount of mobile phase in a chamber was calculated from gray scale values of videos recorded by an image processing routine in ImageJ®. To visualize the flow of the stationary phase polyethylene particles were used to perform a qualitative particle image velocimetry (PIV) analysis. We found a good agreement between flow patterns and velocity profiles of experiments and simulations. By using the model we found that increasing the chamber depth leads to higher specific interfacial area. Additionally a circular flow in the stationary phase was identified that lowers the interfacial area because it pushes the jet of mobile phase to the chamber wall. The Coriolis force alone gives the impulse for this behavior. As a result the model is easier to handle than experiments and allows 3D prediction of hydrodynamics in the chamber. Additionally it can be used for optimizing geometry and operating parameters for given physical properties of solvent systems. PMID:21324465

Adelmann, S; Schwienheer, C; Schembecker, G

2011-09-01

15

A note on secondary flow in rotating radial channels  

NASA Technical Reports Server (NTRS)

A general vector differential equation for the vorticity component parallel to a streamline is derived for steady, nonviscous, and incompressible flow in a rotating system. This equation is then simplified by restricting it to rotating radial channels and by making further simplifying assumptions. The simplified equation is used to solve for the secondary vorticity, the vorticity component parallel to the streamline, in three special cases involving different streamtube geometries; the results are presented in a series of figures. The secondary vorticity is shown to decrease with decreased absolute angular velocity of the fluid, decreased inlet total-pressure gradient, decreased length of relative flow path, and increased relative velocity.

Kramer, James J; Stanitz, John D

1954-01-01

16

Onset of radial flow in p+p collisions  

E-print Network

It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The signal of the collective motion in p+p collisions is not as clear/clean as in heavy-ion collisions because of the low multiplicity and large fluctuation in p+p collisions. Tsallis Blast-Wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p+p collisions from RHIC to LHC using TBW and found no appreciable radial flow in p+p collisions below $\\sqrt{s}=900$ GeV. At LHC higher energy of 7 TeV in p+p collisions, the radial flow velocity achieves an average value of $= 0.320\\pm0.005$. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC. Breaking of the identified particle spectra $m_T$ scaling was also observed at LHC from a model independent test.

Kun Jiang; Yinying Zhu; Weitao Liu; Hongfang Chen; Cheng Li; Lijuan Ruan; Ming Shao; Zebo Tang; Zhangbu Xu

2014-12-23

17

Radial accretion flows on static spherically symmetric black holes  

E-print Network

We analyze the steady radial accretion of matter into a nonrotating black hole. Neglecting the self-gravity of the accreting matter, we consider a rather general class of static, spherically symmetric and asymptotically flat background spacetimes with a regular horizon. In addition to the Schwarzschild metric, this class contains certain deformation of it which could arise in alternative gravity theories or from solutions of the classical Einstein equations in the presence of external matter fields. Modeling the ambient matter surrounding the black hole by a relativistic perfect fluid, we reformulate the accretion problem as a dynamical system, and under rather general assumptions on the fluid equation of state, we determine the local and global qualitative behavior of its phase flow. Based on our analysis and generalizing previous work by Michel, we prove that for any given positive particle density number at infinity, there exists a unique radial, steady-state accretion flow which is regular at the horizon. We determine the physical parameters of the flow, including its accretion and compression rates, and discuss their dependency on the background metric.

Eliana Chaverra; Olivier Sarbach

2015-01-07

18

Linear and radial flow targets for characterizing downhole flow in perforations  

SciTech Connect

Two types of sandstone targets are commonly used to test flow efficiency of shaped-charge jet perforations: linear targets, in which flow enters only the unperforated end of the cylindrical sample, and radial targets, in which flow enters through the end and sides of the sample. To determine which of these targets best represents downhole conditions, the flow distribution along the length of a perforation has been studied by three-dimensional (3D) finite-element analyses. Linear and radial laboratory targets have been compared with downhole perforations under varying conditions. For ideal perforations, the low-shot-density (LSD) case is adequately represented by the radial target, while the high-shot-density (HSD) case falls between the two targets. With realistic crushed and damaged zones, the HSD closely matches the linear target, and the LSD case falls between the two targets.

Deo, M. (Stanford Univ., CA (USA)); Tariq, S.M. (Schlumberger Well Services, Houston, TX (USA)); Halleck, P.M. (Terra Tek, Inc., Salt Lake City, UT (USA))

1989-08-01

19

DESIGN AND FLOW ANALYSIS OF RADIAL AND MIXED FLOW TURBINE VOLUTES  

Microsoft Academic Search

Radial and mixed flow turbines which are an important component of a turbocharger consist essentially of a volute, a rotor and a diffuser. Vaneless volute turbines, which have reasonable performance and low cost, are the most used in turbochargers for automotive engines. Care has to be done in the design of the volute, whose function is to convert a part

M Abidat; M K Hamidou; M Hachemi; M Hamel

2006-01-01

20

Zonal rate model for stacked membrane chromatography. I: characterizing solute dispersion under flow-through conditions.  

PubMed

Conventional models of both packed-bed and stacked-membrane chromatography typically attribute elution band broadening to non-idealities within the column. However, when the column length to diameter ratio is greatly reduced, as in stacked-membrane chromatography, variations in solute residence times within the feed-distribution (inlet) and eluent-collection (outlet) manifolds can also contribute to band broadening. We report on a new zonal rate model (ZRM) for stacked-membrane chromatography that improves on existing hold-up volume models that rely on one plug-flow reactor and one stirred-tank reactor in series to describe dispersion of solute during transport into and out of the column. The ZRM radially partitions the membrane stack and the hold-up volumes within the inlet and outlet manifolds into zones to better capture non-uniform flow distribution effects associated with the large column diameter to height ratio. Breakthrough curves from a scaled-down anion-exchange membrane chromatography module using ovalbumin as a model protein were collected at flow rates ranging from 1.5 to 20 mL min(-1) under non-binding conditions and used to evaluate the ZRM as well as previous models. The ZRM was shown to be significantly more accurate in describing protein dispersion and breakthrough. The model was then used to decompose breakthrough data, where it was found that variations in solute residence time distributions within the inlet and outlet manifolds make the dominant contribution to solute dispersion over the recommended range of feed flow rates. The ZRM therefore identifies manifold design as a critical contributor to separation quality within stacked-membrane chromatography units. PMID:21703630

Francis, Patrick; von Lieres, Eric; Haynes, Charles A

2011-08-01

21

Computation of flow in radial- and mixed-flow cascades by an inviscid-viscous interaction method  

NASA Technical Reports Server (NTRS)

The use of inviscid-viscous interaction methods for the case of radial or mixed-flow cascade diffusers is discussed. A literature review of investigations considering cascade flow-field prediction by inviscid-viscous iterative computation is given. Cascade aerodynamics in the third blade row of a multiple-row radial cascade diffuser are specifically investigated.

Serovy, G. K.; Hansen, E. C.

1980-01-01

22

Radial base heat-transfer gradients in turbulent flow  

Microsoft Academic Search

An experimental analysis of radial base heat-transfer gradients was conducted to determine the application to base heatshield design for various hypersonic entry vehicles. A geometric relation is derived from previous results to determine the radial base heat-transfer distribution for a slender cone at zero angle of attack. Turbulent heat transfer is shown to vary nearly linearly across a flat base.

B. M. Bulmer

1974-01-01

23

The vergence eye movements induced by radial optic flow: Some fundamental properties of the underlying local-motion detectors  

Microsoft Academic Search

Radial optic flow applied to large random dot patterns is known to elicit horizontal vergence eye movements at short latency, expansion causing convergence and contraction causing divergence: the Radial Flow Vergence Response (RFVR). We elicited RFVRs in human subjects by applying radial motion to concentric circular patterns whose radial luminance modulation was that of a square wave lacking the fundamental:

Y. Kodaka; B. M. Sheliga; E. J. FitzGibbon; F. A. Miles

2007-01-01

24

Radial Gas Flows in Colliding Galaxies: Connecting Simulations and Observations  

E-print Network

(abridged) We investigate the detailed response of gas to the formation of transient and long-lived dynamical structures induced in the early stages of a disk-disk collision, and identify observational signatures of radial gas inflow through a detailed examination of the collision simulation of an equal mass bulge dominated galaxy. Stars respond to the tidal interaction by forming both transient arms and long lived m=2 bars, but the gas response is more transient, flowing directly toward the central regions within about 10^8 years after the initial collision. The rate of inflow declines when more than half of the total gas supply reaches the inner few kpc, where the gas forms a dense nuclear ring inside the stellar bar. The average gas inflow rate to the central 1.8 kpc is \\~7 Msun/yr with a peak rate of 17 Msun/yr. The evolution of gas in a bulgeless progenitor galaxy is also discussed, and a possible link to the ``chain galaxy'' population observed at high redshifts is inferred. The evolution of the structural parameters (the asymmetry and concentration) of both stars and gas are studied in detail. Further, a new structural parameter (the compactness parameter K) that traces the evolution of the size scale of the gas relative to the stellar disk is introduced. Non-circular gas kinematics driven by the perturbation of the non-axisymmetric structure can produce distinct emission features in the "forbidden velocity quadrants'' of the position-velocity diagram (PVD). The dynamical mass calculated using the rotation curve derived from fitting the emission envelope of the PVD can determine the true mass to within 20% to 40%. The evolution of the molecular fraction $M_H2/M_(H2 + HI) and the compactness (K) are potential tracers to quantitatively assign the age of the interaction.

Daisuke Iono; Min S. Yun; J. Christopher Mihos

2004-07-29

25

Computational investigations of axial and radial flow compressor aeromechanics  

NASA Astrophysics Data System (ADS)

The focus of this research is aeromechanics issues in advanced compressors of the type used in modern day high thrust-to-weight ratio aircraft gas turbine engines. The driving factor for the studies undertaken is the High Cycle Fatigue (HCF) failure of gas turbine blades. HCF is a key technology issue in the development and endurance of gas turbine engines that arises primarily due to resonant response of turbomachine blading to unsteady aerodynamic excitation. Because it is a truly coupled nonlinear fluid-structure problem, predicting HCF requires a unified approach to modeling both the fluid and the structure. Considering the serious nature of HCF and the inadequacy of lower order design systems to accurately predict blade vibratory stress, the need to develop advanced predictive tools is pressing. The first aspect of this research therefore addresses the development of a turbomachinery coupled fluid-structure interaction tool to predict flow-induced blade vibration. To this end, the TAM-ALE3D solver is further developed as a derivative of the ALE3D code of Lawrence Livermore National Laboratory. In the second aspect of this research, TAM-ALE3D is validated by predicting viscous blade row unsteady aerodynamics and the modal properties of the stator vane in the baseline configuration of the Purdue Transonic Compressor. It is then used to predict the vane vibratory response excited by rotor wakes at resonance, with the resulting stresses in the range expected. For radial flow compressors, a very limited knowledge base exists on the unsteady aerodynamic and aeroelastic mechanisms that result in HCF. The bulk of this research is thus directed at the understanding of these fundamental unsteady phenomena using TAM-ALE3D as an investigative tool. The energy transfer from the downstream diffuser generated forcing function to the impeller blading is addressed by means of unsteady aerodynamic and aeroelastic analyses. From these computational investigations, the details of the impeller blade excitation are elucidated, and promising directions for future research are identified.

Ramakrishnan, Kishore

26

Radial Gas Flows in Colliding Galaxies: Connecting Simulations and Observations  

NASA Astrophysics Data System (ADS)

We investigate the detailed response of gas to the formation of transient and long-lived dynamical structures induced in the early stages of a disk-disk collision and identify observational signatures of radial gas inflow through a detailed examination of the collision simulation of an equal-mass bulge-dominated galaxy. Our analysis and discussion mainly focuses on the evolution of the diffuse and dense gas in the early stages of the collision, when the two disks are interacting but have not yet merged. Stars respond to the tidal interaction by forming both transient arms and long-lived m=2 bars, but the gas response is more transient, flowing directly toward the central regions within about 108 yr after the initial collision. The rate of inflow declines when more than half of the total gas supply reaches the inner few kiloparsecs, where the gas forms a dense nuclear ring inside the stellar bar. The average gas inflow rate to the central 1.8 kpc is ~7 Msolar yr-1 with a peak rate of 17 Msolar yr-1. Gas with high volume density is found in the inner parts of the postcollision disks at size scales close to the spatial resolution of the simulations, and this may be a direct result of shocks traced by the discontinuity in the gas velocity field. The evolution of gas in a bulgeless progenitor galaxy is also discussed, and a possible link to the ``chain galaxy'' population observed at high redshifts is inferred. The evolution of the structural parameters such as asymmetry and concentration of both stars and gas are studied in detail. Further, a new structure parameter (the compactness parameter K) that traces the evolution of the size scale of the gas relative to the stellar disk is introduced, and this may be a useful tracer to determine the merger chronology of colliding systems. Noncircular gas kinematics driven by the perturbation of the nonaxisymmetric structure can produce distinct emission features in the ``forbidden velocity quadrants'' of the position-velocity diagram (PVD). The dynamical mass calculated using the rotation curve derived from fitting the emission envelope of the PVD can determine the true mass to within 20%-40%. The evolution of the molecular fraction (MH2/MH2+HI) is a potential tracer to quantitatively assign the age of the interaction, but the application to real systems may require additional observational diagnostics to properly assess the exact chronology of the merger evolution.

Iono, Daisuke; Yun, Min S.; Mihos, J. Christopher

2004-11-01

27

Revised injectivity calculations for five-spot patterns during radial flow period  

E-print Network

REVISED INJECTIVITY CALCULATIONS FOR FIVE-SPOT PATTERNS DURING RADIAL FLOW PERIOD A Thesis ROBERT CHRISTIAN SCHLAUDT Submitted to the Graduate School of the Agricultural and. Mechanical College of Texas in partial fulfillment... of the requirements for 0he degree of MASTER OF SCIENCE August', l959 Major Subject. Petroleum Engineering REVISED INJECTIVITY CALCULATIONS FOR FIVE-SPOT PATTERNS DURING RADIAL FLOW PERIOD A Thesis Bg ROBERT CHRISTIAN SCELAUDT Approved as to style and content...

Schlaudt, Robert Christian

2012-06-07

28

MODFLOW procedure to simulate axisymmetric flow in radially heterogeneous and layered aquifer systems  

NASA Astrophysics Data System (ADS)

A procedure is outlined to simulate axisymmetric groundwater flow in radially heterogeneous and layered aquifer systems using the unmodified version of MODFLOW. The procedure is straightforward, as it only requires correction of some of the input parameters. In contrast to other MODFLOW procedures to simulate axisymmetric flow, no restrictions are imposed on the type of flow, the discretization of radial distance, or the parameter values. Hence, the method can deal with both confined and unconfined flow, wellbore storage, and axisymmetric aquifer inhomogeneities including effects of finite-thickness skin and gravel pack. Several test cases are presented, which compare the calculated results with existing analytical solutions, the analytic element solver TTim, and the axisymmetric, finite-difference model MAxSym. It is concluded that the MODFLOW procedure is capable of simulating accurately axisymmetric flow in radially heterogeneous multi-aquifer systems.

Louwyck, Andy; Vandenbohede, Alexander; Bakker, Mark; Lebbe, Luc

2014-08-01

29

Chromatography.  

ERIC Educational Resources Information Center

This booklet presents some activities on chromatography. Directions for preparing leaf pigment extracts using alcohol are given, and paper chromatography and thin-layer chromatography are described as modifications of the basic principles of chromatography. (KHR)

Brantley, L. Reed, Sr.; Demanche, Edna L.; Klemm, E. Barbara; Kyselka, Will; Phillips, Edwin A.; Pottenger, Francis M.; Yamamoto, Karen N.; Young, Donald B.

30

Prediction of radial gas profiles in vertical pipe flow on the basis of bubble size distribution  

Microsoft Academic Search

A method for the prediction of the radial gas profile for a given bubble size distribution is presented. It is based on the assumption of the equilibrium of the forces acting on a bubble perpendicularly to the flow direction. These forces strongly depend on the bubble size [14,18]. For the simulation of transient flow regime effects, the modelling of several

Dirk Lucas; Eckhard Krepper; Horst-Michael Prasser

2001-01-01

31

The Steady Two-Dimensional Radial Flow of Viscous Fluid between Two Inclined Plane Walls  

Microsoft Academic Search

This paper considers the steady two-dimensional radial flow of viscous fluid between plane walls which either converge or diverge. A general solution is obtained in terms of elliptic functions and the various mathematically possible types of flow are discussed.

L. Rosenhead

1940-01-01

32

Radial flow towards well in leaky unconfined aquifer  

NASA Astrophysics Data System (ADS)

An analytical solution is developed for three-dimensional flow towards a partially penetrating large- diameter well in an unconfined aquifer bounded below by a leaky aquitard of finite or semi-infinite extent. The analytical solution is derived using Laplace and Hankel transforms, then inverted numerically. Existing solutions for flow in leaky unconfined aquifers neglect the unsaturated zone following an assumption of instantaneous drainage due to Neuman. We extend the theory of leakage in unconfined aquifers by (1) including water flow and storage in the unsaturated zone above the water table, and (2) allowing the finite-diameter pumping well to partially penetrate the aquifer. The investigation of model-predicted results shows that aquitard leakage leads to significant departure from the unconfined solution without leakage. The investigation of dimensionless time-drawdown relationships shows that the aquitard drawdown also depends on unsaturated zone properties and the pumping-well wellbore storage effects.

Mishra, P. K.; Kuhlman, K. L.

2012-12-01

33

Preprocessor and postprocessor computer programs for a radial-flow finite-element model  

USGS Publications Warehouse

Preprocessing and postprocessing computer programs that enhance the utility of the U.S. Geological Survey radial-flow model have been developed. The preprocessor program: (1) generates a triangular finite element mesh from minimal data input, (2) produces graphical displays and tabulations of data for the mesh , and (3) prepares an input data file to use with the radial-flow model. The postprocessor program is a version of the radial-flow model, which was modified to (1) produce graphical output for simulation and field results, (2) generate a statistic for comparing the simulation results with observed data, and (3) allow hydrologic properties to vary in the simulated region. Examples of the use of the processor programs for a hypothetical aquifer test are presented. Instructions for the data files, format instructions, and a listing of the preprocessor and postprocessor source codes are given in the appendixes. (Author 's abstract)

Pucci, A.A., Jr.; Pope, D.A.

1987-01-01

34

Primary instability mechanisms on the magnetohydrodynamic boundary layer flow over a rotating disk subject to a uniform radial flow  

NASA Astrophysics Data System (ADS)

This paper is devoted to the investigation of three primary linear instability mechanisms due to the resonating disturbance waves present in the three-dimensional incompressible viscous/inviscid rotating disk boundary layer flow, extending our earlier still outer fluid work [M. Turkyilmazoglu, "Resonance instabilities on the boundary layer flow over a rotating-disk under the influence of a uniform magnetic field," J. Eng. Math. 59, 337 (2007)] to a uniform nonzero radial flow. A spatiotemporal linear stability analysis is conducted to search for the influences of physical parameters on the possible important mechanisms of resonances leading to, respectively, the absolute instability, the direct spatial instability, and the direct temporal instability. The radial flow is shown to act in the way of stabilizing all the possible mechanisms considered, more pronouncedly as the magnetic field gets strengthened. The onset of absolute instability and convective temporal instability is found to be more sensitive to the variations in the radial flow than is the onset of convective direct spatial instability. Although a considerable delay of the onset of absolute instability as well as temporal instability can be achieved by increasing the magnitude of the radial flow, the direct spatial resonance instability mechanism persists to occur for low Reynolds numbers, while the flow is still in the laminar regime, which is expected to trigger nonlinearity just prior to transition to turbulence.

Turkyilmazoglu, M.

2009-07-01

35

Anomalous magnetosheath flows and distorted subsolar magnetopause for radial interplanetary magnetic fields  

NASA Astrophysics Data System (ADS)

On 12 August 2007 from 1436 to 1441 UT, when the five THEMIS probes (THA, THB, THC, THD, and THE) were located near the subsolar magnetopause, a sunward flow was observed in the magnetosheath. A fast anti-sunward flow (-280 km/s) was observed in the magnetosheath before the sunward flow. Although THA observed this fast anti-sunward flow, THC and THD, which were also in the magnetosheath, instead observed a slow flow, indicating that the fast flow was small in scale. With the observed flow vectors and the magnetopause normal directions estimated from tangential discontinuity analysis, we conclude that this fast flow creates an indentation on the magnetopause, 1 R E deep and 2 R E wide. The magnetopause subsequently rebounds, rotating the flow direction sunward along the surface of the magnetopause. The fast flow is likely related to the radial interplanetary magnetic field.

Shue, J.-H.; Chao, J.-K.; Song, P.; McFadden, J. P.; Suvorova, A.; Angelopoulos, V.; Glassmeier, K. H.; Plaschke, F.

2009-09-01

36

Anomalous Magnetosheath Flows and Distorted Subsolar Magnetopause for Radial Interplanetary Magnetic Fields  

NASA Astrophysics Data System (ADS)

On 12 August 2007 from 1436 to 1441 UT, when the five THEMIS probes (THA, THB, THC, THD, and THE) were located near the subsolar magnetopause, a sunward flow was observed in the magnetosheath. A fast anti-sunward flow (-280 km/s) was observed in the magnetosheath before the sunward flow. Although THA observed this fast anti-sunward flow, THC and THD, which were also in the magnetosheath, instead observed a slow flow, indicating that the fast flow was small in scale. With the observed flow vectors and the magnetopause normal directions estimated from tangential discontinuity analysis, we conclude that this fast flow creates an indentation on the magnetopause, 1 Re deep and 2 Re wide. The magnetopause subsequently rebounds, rotating the flow direction sunward along the surface of the magnetopause. The fast flow is likely related to the radial interplanetary magnetic field.

Shue, J.; Chao, J. K.; Song, P.; McFadden, J. P.; Suvorova, A.; Angelopoulos, V.; Glassmeier, K.; Plaschke, F.

2009-12-01

37

Liquid chromatography/Fourier transform IR spectrometry interface flow cell  

DOEpatents

A zero dead volume (ZDV) microbore high performance liquid chromatography (..mu.. HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a ..mu.. HPLC column end fitting to minimize the transfer volume of the effluents exiting the ..mu.. HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF/sub 2/), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

Johnson, C.C.; Taylor, L.T.

1985-01-04

38

Liquid chromatography/Fourier transform IR spectrometry interface flow cell  

DOEpatents

A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

Johnson, Charles C. (Fairfield, OH); Taylor, Larry T. (Blacksburg, VA)

1986-01-01

39

Radial heterogeneity of some analytical columns used in high-performance liquid chromatography  

SciTech Connect

An on-column electrochemical microdetector was used to determine accurately the radial distribution of the mobile phase velocity and of the column efficiency at the exit of three common analytical columns, namely a 100 mm x 4.6 mm C18 bonded silica-based monolithic column, a 150 mm x 4.6 mm column packed with 2.7 {micro}m porous shell particles of C18 bonded silica (HALO), and a 150 mm x 4.6 mm column packed with 3 {micro}m fully porous C18 bonded silica particles (LUNA). The results obtained demonstrate that all three columns are not radially homogeneous. In all three cases, the efficiency was found to be lower in the wall region of the column than in its core region (the central core with a radius of 1/3 the column inner radius). The decrease in local efficiency from the core to the wall regions was lower in the case of the monolith (ca. 25%) than in that of the two particle-packed columns (ca. 35-50%). The mobile phase velocity was found to be ca. 1.5% higher in the wall than in the core region of the monolithic column while, in contrast, it was ca. 2.5-4.0% lower in the wall region for the two particle-packed columns.

Mriziq, Khaled S [ORNL; Guiochon, Georges A [ORNL

2009-01-01

40

Effects of Skeletonized versus Pedicled Radial Artery on Postoperative Graft Patency and Flow  

PubMed Central

Background Radial artery (RA) was the second arterial graft introduced in clinical practice for myocardial revascularization. The skeletonization technique of the left internal thoracic artery (LITA) may actually change the graft's flow capacity with potential advantages. This leads to the assumption that the behavior of the RA, as a coronary graft, is similar to that of the LITA, when skeletonized. Objective This study evaluated 'free' aortic-coronary radial artery (RA) grafts, whether skeletonized or with adjacent tissues. Methods A prospective randomized study comparing 40 patients distributed into two groups was conducted. In group I, we used skeletonized radial arteries (20 patients), and in group II, we used radial arteries with adjacent tissues (20 patients). After the surgical procedure, patients underwent flow velocity measurements. Results The main surgical variables were: RA internal diameter, RA length, and free blood flow in the radial artery. The mean RA graft diameters as calculated using quantitative angiography in the immediate postoperative period were similar, as well as the flow velocity measurement variables. On the other hand, coronary cineangiography showed the presence of occlusion in one RA graft and stenosis in five RA grafts in GII, while GI presented stenosis in only one RA graft (p = 0.045). Conclusion These results show that the morphological and pathological features, as well as the hemodynamic performance of the free radial artery grafts, whether prepared in a skeletonized manner or with adjacent tissues, are similar. However, a larger number of non-obstructive lesions may be observed when RA is prepared with adjacent tissues. PMID:24918911

Bonini, Rômulo C. Arnal; Staico, Rodolfo; Issa, Mario; Arnoni, Antoninho Sanfins; Chaccur, Paulo; Abdulmassih, Camilo; Dinkhuysen, Jarbas Jackson; Paulista, Paulo Paredes; de Souza, Luiz Carlos Bento; Moreira, Luiz Felipe P.

2014-01-01

41

Discrete Structures in the Radial Flow Over a Rotor Blade in Dynamic Stall  

E-print Network

Discrete Structures in the Radial Flow Over a Rotor Blade in Dynamic Stall James DiOttavio , Kevin blade undergoing dynamic stall in forward flight. It follows our finding of such structures over a blade undergoing transient stall induced by an inflow obstructer in a hover facility. Co-rotating structures

42

Radial Flow Measurements Downstream of Forced Dynamic Separation on a Rotor Blade  

E-print Network

to balance the moments on the advancing and retreating sides of the rotor disc. The pitch increaseRadial Flow Measurements Downstream of Forced Dynamic Separation on a Rotor Blade Jaesuk Yang separation is forced on the suction side of a rotor blade in a hover facility, to study the development

43

Experimental and theoretical investigations of the flow in radial impellers of centrifugal pumps at cavitation  

Microsoft Academic Search

The relationship between NPSH (Non Positive Suction Head) cavitation phenomena and energy transfer has been investigated by means of optical observation of the flow in radial impellers of centrifugal pumps. By using the model assumption that cavitation areas are limited by the isobaric line of vapor pressure it is possible to calculate the development of the cavitation area at decreasing

H.-J. Kleinert; G. Will; R. Finzel

1979-01-01

44

Flow fields behind a variable-area nozzle for radial turbines  

Microsoft Academic Search

The flow fields behind a variable-area nozzle for radial turbines were measured in detail using a three-hole cobra probe in 15 cases, which are a combination of three nozzle throat areas (0.8, 1.0, and 1.4 times the rated area) and five values of the tip-clearance to blade-height ratio (between 0.0 to 0.099). The flow fields at different tip clearances are

Hiroshi Hayami; Yong-Ik Hyun; Yasutoshi Senoo; Michiteru Yamaguchi

1987-01-01

45

Chromatography  

NSDL National Science Digital Library

This site provides fundamental background information about chromatography, including plate theory, rate theory, the mechanisms of separations, and qualitative and quantitative aspects of chromatography. The format is a series of PowerPoint-like presentations available in PDF format.

Hardy, James K.

46

Radial spreading of drift-wave-zonal-flow turbulence via soliton formation.  

PubMed

The self-consistent spatiotemporal evolution of a drift-wave (DW) radial envelope and a zonal-flow (ZF) amplitude is investigated in a slab model. The stationary solution of the coupled partial differential equations in a simple limit yields the formation of DW-ZF soliton structures, which propagate radially with speed depending on the envelope peak amplitude. Additional interesting physics, e.g., the generation, destruction, collision, and reflection of solitons, as well as turbulence bursting can also be observed due to the effects of linear growth or damping, dissipation, equilibrium nonuniformities and soliton dynamics. The propagation of soliton causes significant radial spreading of DW turbulence and therefore can affect transport scaling with the system size by broadening of the turbulent region. The correspondence of the present analysis with the description of DW-ZF interactions in toroidal geometry is also discussed. PMID:19792508

Guo, Zehua; Chen, Liu; Zonca, Fulvio

2009-07-31

47

Occurrence of turbulent flow conditions in supercritical fluid chromatography.  

PubMed

Having similar densities as liquids but with viscosities up to 20 times lower (higher diffusion coefficients), supercritical CO2 is the ideal (co-)solvent for fast and/or highly efficient separations without mass-transfer limitations or excessive column pressure drops. Whereas in liquid chromatography the flow remains laminar in both the packed bed and tubing, except in extreme cases (e.g. in a 75 ?m tubing, pure acetonitrile at 5 ml/min), a supercritical fluid can experience a transition from laminar to turbulent flow in more typical operation modes. Due to the significant lower viscosity, this transition for example already occurs at 1.3 ml/min for neat CO2 when using connection tubing with an ID of 127 ?m. By calculating the Darcy friction factor, which can be plotted versus the Reynolds number in a so-called Moody chart, typically used in fluid dynamics, higher values are found for stainless steel than PEEK tubing, in agreement with their expected higher surface roughness. As a result turbulent effects are more pronounced when using stainless steel tubing. The higher than expected extra-column pressure drop limits the kinetic performance of supercritical fluid chromatography and complicates the optimization of tubing ID, which is based on a trade-off between extra-column band broadening and pressure drop. One of the most important practical consequences is the non-linear increase in extra-column pressure drop over the tubing downstream of the column which leads to an unexpected increase in average column pressure and mobile phase density, and thus decrease in retention. For close eluting components with a significantly different dependence of retention on density, the selectivity can significantly be affected by this increase in average pressure. In addition, the occurrence of turbulent flow is also observed in the detector cell and connection tubing. This results in a noise-increase by a factor of four when going from laminar to turbulent flow (e.g. going from 0.5 to 2.5 ml/min for neat CO2). PMID:25145564

De Pauw, Ruben; Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

2014-09-26

48

Simulating MODFLOW-based reactive transport under radially symmetric flow conditions.  

PubMed

Radially symmetric flow and solute transport around point sources and sinks is an important specialized topic of groundwater hydraulics. Analysis of radial flow fields is routinely used to determine heads and flows in the vicinity of point sources or sinks. Increasingly, studies also consider solute transport, biogeochemical processes, and thermal changes that occur in the vicinity of point sources/sinks. Commonly, the analysis of hydraulic processes involves numerical or (semi-) analytical modeling methods. For the description of solute transport, analytical solutions are only available for the most basic transport phenomena. Solving advanced transport problems numerically is often associated with a significant computational burden. However, where axis-symmetry applies, computational cost can be decreased substantially in comparison with full three-dimensional (3D) solutions. In this study, we explore several techniques of simulating conservative and reactive transport within radial flow fields using MODFLOW as the flow simulator, based on its widespread use and ability to be coupled with multiple solute and reactive transport codes of different complexity. The selected transport simulators are MT3DMS and PHT3D. Computational efficiency and accuracy of the approaches are evaluated through comparisons with full 2D/3D model simulations, analytical solutions, and benchmark problems. We demonstrate that radial transport models are capable of accurately reproducing a wide variety of conservative and reactive transport problems provided that an adequate spatial discretization and advection scheme is selected. For the investigated test problems, the computational load was substantially reduced, with the improvement varying, depending on the complexity of the considered reaction network. PMID:22900478

Wallis, Ilka; Prommer, Henning; Post, Vincent; Vandenbohede, Alexander; Simmons, Craig T

2013-01-01

49

Segmented flow and curtain flow chromatography: overcoming the wall effect and heterogeneous bed structures.  

PubMed

The variation in mobile phase velocity as a function of the column radius has been shown to be a major limitation in the efficiency of HPLC columns. One contributing factor to the variability in the flow velocity stems from the heterogeneity in the radial packing density, leading to what has been described as the 'wall-effect'. The wall-effect generates parabolic-type elution profiles, which dilutes the sample and creates tailing bands. In this communication a new column technology is discussed that has been designed to overcome the wall effect, minimising the limitations associated with packing heterogeneity. This technology has been referred to as active flow technology and consists of two types of column designs, parallel segmented flow and curtain flow. In both these column designs sample that elutes through the column in the radial central region of the bed is separated from the flow that elutes along the wall region. Hence, the sample that elutes through the most efficiently packed region of the bed is collected to the detector. As a consequence more theoretical plates are obtained, and sensitivity is increased since the sample is not diluted by the diffuse tail. Sensitivity is enhanced further in the curtain flow design. The benefits of these new columns are discussed. PMID:23958688

Shalliker, Ross Andrew; Ritchie, Harald

2014-03-28

50

Stability results for multi-layer radial Hele-Shaw and porous media flows  

NASA Astrophysics Data System (ADS)

Motivated by stability problems arising in the context of chemical enhanced oil recovery, we perform linear stability analysis of Hele-Shaw and porous media flows in radial geometry involving an arbitrary number of immiscible fluids. Key stability results obtained and their relevance to the stabilization of fingering instability are discussed. Some of the key results, among many others, are (i) absolute upper bounds on the growth rate in terms of the problem data; (ii) validation of these upper bound results against exact computation for the case of three-layer flows; (iii) stability enhancing injection policies; (iv) asymptotic limits that reduce these radial flow results to similar results for rectilinear flows; and (v) the stabilizing effect of curvature of the interfaces. Multi-layer radial flows have been found to have the following additional distinguishing features in comparison to rectilinear flows: (i) very long waves, some of which can be physically meaningful, are stable; and (ii) eigenvalues can be complex for some waves depending on the problem data, implying that the dispersion curves for one or more waves can contact each other. Similar to the rectilinear case, these results can be useful in providing insight into the interfacial instability transfer mechanism as the problem data are varied. Moreover, these can be useful in devising smart injection policies as well as controlling the complexity of the long-term dynamics when drops of various immiscible fluids intersperse among each other. As an application of the upper bound results, we provide stabilization criteria and design an almost stable multi-layer system by adding many layers of fluid with small positive jumps in viscosity in the direction of the basic flow.

Gin, Craig; Daripa, Prabir

2015-01-01

51

Micellar electrokinetic chromatography in zero-electroosmotic flow environment.  

PubMed

Micellar electrokinetic chromatography (MEKC) is conducted in polyacrylamide-coated capillaries under almost complete suppression of electroosmotic flow. The equations of migration and resolution for neutral solutes in this mode of MEKC operation are presented. The technique is termed reversed-flow MEKC (RF-MEKC) because, in contrast to MEKC in bare-silica capillaries (N-MEKC), solute migration order is reversed and solute migration time is inversely proportional to micelle concentration. This presents an advantage for the high-efficiency separation of extremely and moderately hydrophobic solutes in a short analysis time. Examples of the separation of polycyclic aromatic hydrocarbons, aflatoxins and dansylated-amino acids are presented using sodium dodecyl sulfate (SDS) surfactant. Polycyclic aromatic hydrocarbons are separated using a relatively low micelle concentration. The detection sensitivity for these compounds is enhanced in two ways. First, the peaks are sharp because of the short analysis time and the inertness of the column surface. Second, the fluorescence background and Joule's heating are minimal because of the low concentration of SDS and other additives needed to affect the separation. While N-MEKC is mainly conducted with basic buffers, RF-MEKC can be conducted in basic as well as acidic media as illustrated in the separation of 15 dansylated-amino acids at pH 4.2. PMID:8876436

Janini, G M; Muschik, G M; Issaq, H J

1996-08-01

52

On Analysis of Stationary Viscous Incompressible Flow Through a Radial Blade Machine  

NASA Astrophysics Data System (ADS)

The paper is concerned with the analysis of the two dimensional model of incompressible, viscous, stationary flow through a radial blade machine. This type of turbine is sometimes called Kaplan's turbine. In the technical area the use is either to force some regular characteristic to the flow of the medium going through the turbine (flow of melted iron, air conditioning) or to gain some energy from the flowing medium (water). The inflow and outflow part of boundary are in general a concentric circles. The larger one represents an inflow part of boundary the smaller one the outflow part of boundary. Between them are regularly spaced the blades of the machine. We study the existence of the weak solution in the case of nonlinear boundary condition of the "do-nothing" type. The model is interesting for study the behavior of the flow when the boundary is formed by mutually disjoint and separated parts.

Neustupa, Tomáš

2010-09-01

53

Why is the radial flow in central pA collisions stronger than in AA?  

NASA Astrophysics Data System (ADS)

Both the transverse size and entropy density per area in central pA collisions is smaller than in central AA, and yet the radial flow is stronger. We propose an explanation to this puzzle. Using a weak attraction between strings through the ?-meson exchange, fitted to the lattice data, we find collective implosion of the 'spaghetti' multi-string state. Collectivization of the sigma field of the strings is the QCD analog of the black hole formation occurring in holographic models.

Kalaydzhyan, Tigran; Shuryak, Edward

2014-11-01

54

Buoyancy-driven flow reversal phenomena in radially rotating serpentine ducts  

Microsoft Academic Search

Convective characteristics are analyzed numerically in a rotating multipass square duct connecting with 180-deg sharp returns. Isoflux is applied to each duct wall and periodic conditions are used between the entrance and exit of a typical two-pass module. Emphasis is placed on the phenomenon of buoyancy-driven reversed flow in the serpentine duct. Predictions reveal that the radial distance from the

J. J. Hwang; W.-J. Wang; Cha’o Kuang Chen

2000-01-01

55

Incorporating radial mixing in axisymmetric streamline curvature through-flow analysis  

NASA Astrophysics Data System (ADS)

The development of governing equations for hub-to-tip streamline curvature solutions in turbomachinery passages and blade rows and incorporating viscous radial mixing is presented. Arbitrary passage geometries and quasi-orthogonal description are accounted for. Fortran program coding is carried out for the special case of unbladed, axial-flow passages. Flow solutions are obtained by iteration based on fixed streamline patterns in the meridional plane followed by further iterations involving readjustment of the streamlines until overall convergence is obtained. Simple examples are presented to illustrate the solution technique.

Grabowska, D. G.; Kavanagh, P.

1993-09-01

56

Instability of the vertical annular flow with a radial heating and rotating inner cylinder  

NASA Astrophysics Data System (ADS)

A linear stability analysis of the flow confined in a differentially rotating cylindrical annulus with a radial temperature gradient has been performed. Depending on values of control parameters (the Taylor number, the Grashof number, and the Froude number), it has shown flow destabilization to axisymmetric or non-axisymmetric modes. Analysis of different terms involved in the evolution rate of the perturbation kinetic energy has allowed us to isolate the dominant terms (centrifugal force or buoyancy force) in the destabilization process. We have shown that the centrifugal buoyancy can induce the asymmetry of the temperature gradient on critical states.

Yoshikawa, H. N.; Nagata, M.; Mutabazi, I.

2013-11-01

57

An analysis of the viscous flow through a compact radial turbine by the average passage approach  

NASA Technical Reports Server (NTRS)

A steady, three-dimensional viscous average passage computer code is used to analyze the flow through a compact radial turbine rotor. The code models the flow as spatially periodic from blade passage to blade passage. Results from the code using varying computational models are compared with each other and with experimental data. These results include blade surface velocities and pressures, exit vorticity and entropy contour plots, shroud pressures, and spanwise exit total temperature, total pressure, and swirl distributions. The three computational models used are inviscid, viscous with no blade clearance, and viscous with blade clearance. It is found that modeling viscous effects improves correlation with experimental data, while modeling hub and tip clearances further improves some comparisons. Experimental results such as a local maximum of exit swirl, reduced exit total pressures at the walls, and exit total temperature magnitudes are explained by interpretation of the flow physics and computed secondary flows. Trends in the computed blade loading diagrams are similarly explained.

Heidmann, James D.; Beach, Timothy A.

1990-01-01

58

Three dimensional LDV flow measurements and theoretical investigation in a radial inflow turbine scroll  

NASA Technical Reports Server (NTRS)

A two-color LDV system was used in the measurement of three orthogonal velocity components at 758 points located throughout the scroll and the unvaned portion of the nozzle of a radial inflow turbine scroll. The cold flow experimental results are presented for the velocity field at the scroll tongue. In addition, a total pressure loss of 3.5 percent for the scroll is revealed from the velocity measurements combined with the static pressure readings. Moreover, the measurement of the three normal stresses of the turbulence has showed that the flow is anisotropic. Furthermore, the mean velocity components are compared with a numerical solution of the potential flow field using the finite element technique. The theoretical prediction of the exit flow angle variation agrees well with the experimental results. This variation leads to a higher scroll pattern factor which can be avoided by controlling the scroll cross sectional area distribution.

Malak, Malak Fouad; Hamed, Awatef; Tabakoff, Widen

1990-01-01

59

Chromatography  

NSDL National Science Digital Library

This lab activity from the Biotechnology Alliance for Suncoast Biology Educators covers background information on the basic types of chromatography and has the student separate pigments extracted from pens and plant leaves using paper chromatography. The lesson includes the materials needed and the demonstration procedures.

Keirle, Matt

60

Intrapericardial denervation - Radial artery blood flow and heart rate responses to LBNP  

NASA Technical Reports Server (NTRS)

The effects of intrapericardial denervation on the radial artery blood flow velocity (RABFV) and heart rate (HR) responses to LBNP in rhesus monkeys were investigated by measuring the RABFV transcutaneously by a continuous-wave Doppler ultrasonic flowmeter in order to derive an index of forearm blood flow response to low (0 to -20 mm Hg) and high (0 to -60 mm Hg) ramp exposures during supine LBNP. Four of the eight subjects were subjected to efferent and afferent cardiac denervation. It was found that, during low levels of LBNP, monkeys with cardiac denervation exhibited no cardiopulmonary baroreceptor-mediated change in the RABFV or HR, unlike the intact animals, which showed steady decreases in RABFV during both high- and low-pressure protocols. It is suggested that forearm blood flow and HR responses to low-level LBNP, along with pharmacological challenge, are viable physiological tests for verifying the completeness of atrial and cardiopulmonary baroreceptor denervation.

Mckeever, Kenneth H.; Skidmore, Michael G.; Keil, Lanny C.; Sandler, Harold

1990-01-01

61

An analytical solution for transient radial flow through unsaturated fractured porous media  

SciTech Connect

This paper presents analytical solutions for one-dimensional radial transient flow through horizontal, unsaturated fractured rock formation. In these solutions, unsaturated flow through fractured media is described by a linearized Richards' equation, while fracture-matrix interaction is handled using the dual-continuum concept. Although linearizing Richards' equation requires a specially correlated relationship between relative permeability and capillary pressure functions for both fractures and matrix, these specially formed relative permeability and capillary pressure functions are still physically meaningful. These analytical solutions can thus be used to describe the transient behavior of unsaturated flow in fractured media under the described model conditions. They can also be useful in verifying numerical simulation results, which, as demonstrated in this paper, are otherwise difficult to validate.

Wu, Yu-Shu; Pan, Lehua

2004-02-13

62

Chromatography  

NSDL National Science Digital Library

In this activity, explore chromatography and the various colors that make up the ink in markers. Use this activity to investigate cohesion and adhesion. The online version of this activity is set up so that learners solve a mystery.

WGBH Boston

2002-01-01

63

A difference equation model for radial flow at small Reynolds number  

E-print Network

Vechsnical En ines~rib A DIFFERENCE EQUATIOh 1'ODEL FOR RADIAL FLOYi AT SMALL REYNOLDS EDI&BFR A Thesis by Fred. Lyrw Gcldsberry AFproved "s to style and coster t by: Dx. C. . E . leborolig Dr. C. V. S''mmar g Dr. J. G. H. Thorn@so Ifr. B. C. Moore... ~u 1 69 AESTPACT A Difference Fquation?odel for Padial Flow a, t Small Peynolds Dumber (January, 1969) Fred Lynn Qoldsberry, B. S. Texas Ak'. ~ Dniversity Directed by: Dr. C. F. Kettleborough This study has produced a difference equation model...

Goldsberry, Fred Lynn

1969-01-01

64

Eigenmodes of Ducted Flows With Radially-Dependent Axial and Swirl Velocity Components  

NASA Technical Reports Server (NTRS)

This report characterizes the sets of small disturbances possible in cylindrical and annular ducts with mean flow whose axial and tangential components vary arbitrarily with radius. The linearized equations of motion are presented and discussed, and then exponential forms for the axial, circumferential, and time dependencies of any unsteady disturbances are assumed. The resultant equations form a generalized eigenvalue problem, the solution of which yields the axial wavenumbers and radial mode shapes of the unsteady disturbances. Two numerical discretizations are applied to the system of equations: (1) a spectral collocation technique based on Chebyshev polynomial expansions on the Gauss-Lobatto points, and (2) second and fourth order finite differences on uniform grids. The discretized equations are solved using a standard eigensystem package employing the QR algorithm. The eigenvalues fall into two primary categories: a discrete set (analogous to the acoustic modes found in uniform mean flows) and a continuous band (analogous to convected disturbances in uniform mean flows) where the phase velocities of the disturbances correspond to the local mean flow velocities. Sample mode shapes and eigensystem distributions are presented for both sheared axial and swirling flows. The physics of swirling flows is examined with reference to hydrodynamic stability and completeness of the eigensystem expansions. The effect of assuming exponential dependence in the axial direction is discussed.

Kousen, Kenneth A.

1999-01-01

65

A high power density radial-in-flow reactor split core design for space power systems  

NASA Astrophysics Data System (ADS)

Application of the Rankine cycle to space power systems is difficult because of the problems and complexities associated with two phase flow systems in microgravity. A direct cycle system which could provide super heated vapor to the turbine inlet would greatly enhance the development of Rankine cycle power systems for space applications. The split core radial-in-flow reactor design provides a safe reliable core design for space power systems. It makes direct Rankine cycle power systems a very competitive design, eliminating the boiler and additional pumps of an indirect cycle along with the liquid vapor separator. A continuous power Rankine cycle system using this core design would produce the least weight system of any having the same power output.

Coomes, Edmund P.

66

Evidence for radial flow of thermal dileptons in high-energy nuclear collisions  

E-print Network

The NA60 experiment at the CERN SPS has studied low-mass dimuon production in 158 AGeV In-In collisions. An excess of pairs above the known meson decays has been reported before. We now present precision results on the associated transverse momentum spectra. The slope parameter Teff extracted from the spectra rises with dimuon mass up to the rho, followed by a sudden decline above. While the initial rise is consistent with the expectations for radial flow of a hadronic decay source, the decline signals a transition to an emission source with much smaller flow. This may well represent the first direct evidence for thermal radiation of partonic origin in nuclear collisions.

NA60 Collaboration; R. Arnaldi

2007-11-12

67

On the Exact Solution for Axisymmetric Flow and Heat Transfer over a Nonlinear Radially Stretching Sheet  

NASA Astrophysics Data System (ADS)

We investigate the boundary-layer flow and heat transfer of a magnetohydrodynamic viscous fluid over a nonlinear radially porous stretching sheet within a porous medium. The flow is generated due to a nonlinear stretching sheet and influenced by a continuous suction/blowing of the fluid through the porous sheet. The governing momentum and thermal boundary layer equations are converted into ordinary differential equations by appropriate similarity transformations. The exact solution for the velocity and the temperature fields are derived in the form of an incomplete Gamma function. Also analytic solutions are found by the homotopy analysis method. The graphical results for velocity and temperature fields are presented and discussed. Further, the numerical values of the skin friction coefficient and the Nusselt number are calculated and discussed.

Azeem, Shahzad; Ramzan, Ali; Masood, Khan

2012-08-01

68

Equation of state, radial flow, and freeze-out in high energy heavy ion collisions  

NASA Astrophysics Data System (ADS)

We have shown that recent experimental data on radial flow, both from AGS and SPS energies, are in agreement with the equation of state (EOS) including the QCD phase transition. A new hydrokinetic model (HKM) is developed, which incorporates a hydrodynamical treatment of the expansion and proper kinetics of the freeze-out. We show that the freeze-out surfaces for different secondaries and different collisions are very different, and they are not at all isotherms T=const (as was assumed in most previous hydrodynamics works). Comparison of HKM results with the cascade-based event generator RQMD is also made in some detail: we found that both the EOS and flow are in rather good agreement, while the space-time picture is still somewhat different.

Hung, C. M.; Shuryak, E.

1998-04-01

69

Optimization and evaluation of radially interconnected versus bifurcating flow distributors using computational fluid dynamics modelling.  

PubMed

Two main groups of flow distributors, viz. "bifurcating distributors" (BF) and "radially interconnected distributors" (RI), as well as some hybrid distributors were investigated. Computational fluid dynamics was used to evaluate the performance of the distributors and to establish the design yielding the most uniform velocity field and the smallest variance for the bands emerging from the distributor. A minimum channel width of 100?m was considered to allow the use of micro-milling techniques for chip fabrication. The main factors that influenced the values of band variances were identified. The performance of the distributors was found to correlate most strongly with the volume of the flow distributors. The separation bed should be positioned immediately after, but not against the flow distributor. It was concluded that BF distributors perform best in terms of band variance. The values of band variances for the BF distributor decreased with increasing angle between bifurcation branches and the lowest value of about 0.01mm(2) was found for ?=175°. Both BF and RI flow distributors were found to perform reasonably well when imperfections were present in the structure. However, severe blockages (exceeding 75% of the cross-sectional area and length) of channels in, especially, BF flow distributors may jeopardize their performance. PMID:25591402

Davydova, E; Deridder, S; Eeltink, S; Desmet, G; Schoenmakers, P J

2015-02-01

70

Chromatography  

NSDL National Science Digital Library

The North Carolina Community College System BioNetwork's interactive eLearning tools (IETs) are reusable chunks of training that can be deployed in a variety of courses or training programs. IETs are designed to enhance, not replace hands-on training. Learners are able to enter a hands-on lab experience better prepared and more confident. This particular IET delves into chromatography including the basics, the three types (affinity, ion exchange, size exclusion), and the parts and functions associated with chromatography.

71

The optimal flow rate and column length for maximum production rate of protein A affinity chromatography  

Microsoft Academic Search

Production rate is an important parameter in the design of efficient protein A affinity chromatography processes for purifying recombinant monoclonal antibodies. A simple equation was derived that expresses production rate in terms of flow rate and column length. Changes in flow rate and column length will not affect the antibody and are therefore easily varied for bioprocess applications. In the

R. L. Fahrner; H. V. Iyer; G. S. Blank

1999-01-01

72

Investigation of the influence of radial grooves on the flow in an eccentrically deposited annulus using CFD numerical simulation  

NASA Astrophysics Data System (ADS)

This paper evaluates the influence of radial grooves in the eccentrically deposited annulus using by mathematical modeling of fluid flow through each grooves. The inner cylinder (rotor) is eccentrically deposited and its movement is composed of two movements (rotation and precession). The outer cylinder is stationary and has radial grooves. In the first phase is defined a mathematical model of the flow, which is then applied to the 3D model of narrow gap with radial grooves. In this paper are present several variants of the computational domain with regard to the number of radial grooves. Based on the results of numerical simulations are evaluated basic variables such as pressure and velocity. There are also evaluated radial force (Fr) and axial force (Fa) acting on the rotor for different boundary conditions (different speeds of rotation and precession). Subsequently, the pressure gradients (?p) are evaluated between the radial grooves for different computational domain. Results are compared to variant of narrow gap without radial grooves. Numerical simulation is realized in the program system ANSYS Fluent.

Bojko, Marian; Kozubkova, Milada; Kozdera, Michal; Zavila, Ond?ej

2014-03-01

73

Radial-radial single rotor turbine  

DOEpatents

A rotor for use in turbine applications has a radial compressor/pump having radially disposed spaced apart fins forming passages and a radial turbine having hollow turbine blades interleaved with the fins and through which fluid from the radial compressor/pump flows. The rotor can, in some applications, be used to produce electrical power.

Platts, David A. (Los Alamos, NM)

2006-05-16

74

Chromatography  

NSDL National Science Digital Library

In this activity, by the Concord Consortium's Molecular Literacy project, students "learn about the phases of molecular separation, and then experiment with paper and ion chromatography." The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In addition, visitors will find an overview of the activity, assessments, and concepts and their correlation to AAAS and NSES standards.

75

Chromatography  

NSDL National Science Digital Library

In this chemistry activity, learners will separate a mixture of FD&C dyes (colors certified and allowed by the US for the Food, Pharmaceutical, Cosmetics & Personal Care industry) to practice chromatography, a separation technique for mixtures. Learners will record their observations on a data table and note trends. This resource includes questions for learners and instructions for preparing the colors from M&Ms, Orange Kool-Aid, and food coloring.

2014-01-28

76

Three-dimensional flow in radial turbomachinery and its impact on design  

NASA Technical Reports Server (NTRS)

In the two papers on the 'Theory of Blade Design for Large Deflections' published in 1984, a new inverse design technique was presented for designing the shape of turbomachinery blades in three-dimensional flow. The technique involves the determination of the blade profile from the specification of a distribution of the product of the radius and the pitched averaged tangential velocity (i.e., r bar-V(sub theta), the mean swirl schedule) within the bladed region. This is in contrast to the conventional inverse design technique for turbomachinery blading in two dimensional flow in which the blade surface pressure or velocity distribution is specified and the blade profile determined as a result; this is feasible in two-dimensional flow because the streamlines along the blade surfaces are known a priori. However, in three-dimensional flow, the stream surface is free to deform within the blade passage so that the streamlines on the blade surfaces are not known a priori; thus it is difficult and not so useful to prescribe the blade surface pressure or velocity distribution and determine the resulting blade profile. It therefore seems logical to prescribe the swirl schedule within the bladed region for designing a turbomachinery blade profile in three-dimensional flow. Furthermore, specifying r bar-V(sub theta) has the following advantages: (1) it is related to the circulation around the blade (i.e., it is an aerodynamic quantity); (2) the work done or extracted is approximately proportional to the overall change in r bar-V(sub theta) across a given blade row (Euler turbine equation); and (3) the rate of change of r bar-V(sub theta) along the mean streamline at the blade is related to the pressure jump across the blade and therefore the blade loading. Since the publications of those two papers, the technique has been applied to the design of a low speed as well as a high speed radial inflow turbine (for turbocharger applications) both of which showed definite improvements in performance over that of wheels of conventional designs, the design study of a high pressure ratio radial inflow turbine with and without splitter blades.

Tan, Choon S.; Hawthorne, William

1993-01-01

77

Experiments on Thermal Convection in Rotating Spherical Shells With Radial Gravity: The Geophysical Fluid Flow Cell  

NASA Technical Reports Server (NTRS)

Experiments designed to study the fluid dynamics of buoyancy driven circulations in rotating spherical shells were conducted on the United States Microgravity Laboratory 2 spacelab mission. These experiments address several aspects of prototypical global convection relevant to large scale motions on the Sun, Earth, and on the giant planets. The key feature is the consistent modeling of radially directed gravity in spherical geometry by using dielectric polarization forces. Imagery of the planforms of thermally driven flows for rapidly-rotating regimes shows an initial separation and eventual merger of equatorial and polar convection as the heating (i.e. the Rayleigh number) is increased. At low rotation rates, multiple-states of motion for the same external parameters were observed.

Hart, John E.

1996-01-01

78

Acoustic geometry through perturbation of mass accretion rate : I - radial flow in general static spacetime  

E-print Network

We propose a novel perturbation scheme to perform the linear stability analysis of stationary transonic integral accretion solutions corresponding to the hydrodynamic non self-gravitating radial flow of matter in a general static black hole spacetime. We demonstrate that a metric independent perturbation scheme can be developed, which leads to the emergence of the relativistic acoustic geometry and ensures the stability of the background stationary solutions. The acoustic metric obtained by perturbing the mass accretion rate rate is found to be identical with that obtained through the perturbation of the velocity potential. Our work thus makes a crucial connection between two apparently disjoint fields of study - accretion astrophysics and analogue gravity phenomena. We also formally prove that acoustic horizons never form in the Rindler spacetime.

Deepika B. Ananda; Sourav Bhattacharya; Tapas K. Das

2014-06-17

79

Aerodynamic design of turbomachinery blading in three-dimensional flow - An application to radial inflow turbines  

NASA Technical Reports Server (NTRS)

A computational method, based on a theory for turbomachinery blading design in three-dimensional inviscid flow, is applied to a parametric design study of a radial inflow turbine wheel. As the method requires the specification of swirl distribution, a technique for its smooth generation within the blade region is proposed. Excellent agreements have been obtained between the computed results from this design method and those from direct Euler computations, demonstrating the correspondence and consistency between the two. The computed results indicate the sensitivity of the pressure distribution to a lean in the stacking axis and a minor alteration in the hub/shroud profiles. Analysis based on Navier-Stokes solver shows no breakdown of flow within the designed blade passage and agreement with that from design calculation; thus the flow in the designed turbine rotor closely approximates that of an inviscid one. These calculations illustrate the use of a design method coupled to an analysis tool for establishing guidelines and criteria for designing turbomachinery blading.

Yang, Y. L.; Tan, C. S.; Hawthorne, W. R.

1992-01-01

80

PIV investigation of the flow induced by a passive surge control method in a radial compressor  

NASA Astrophysics Data System (ADS)

Due to recent emission regulations, the use of turbochargers for force induction of internal combustion engines has increased. Actually, the trend in diesel engines is to downsize the engine by use of turbochargers that operate at higher pressure ratios. Unfortunately, increasing the impeller rotational speed of turbocharger radial compressors tends to reduce their range of operation, which is limited at low mass flow rate by the occurrence of surge. In order to extend the operability of turbochargers, compressor housings can be equipped with a passive surge control device such as a "ported shroud." This specific casing treatment has been demonstrated to enhance the surge margin with minor negative impact on the compressor efficiency. However, the actual working mechanisms of the system remain not well understood. Hence, in order to optimize the design of the ported shroud, it is crucial to identify the dynamic flow changes induced by the implementation of the device to control instabilities. From the full dynamic survey of the compressor performance characteristics obtained with and without ported shroud, specific points of operation were selected to carry out planar flow visualization. At normal working, both standard and stereoscopic particle imaging velocimetry (PIV) measurements were performed to evaluate instantaneous and mean velocity flow fields at the inlet of the compressor. At incipient and full surge, phase-locked PIV measurements were added. As a result, satisfying characterization of the compressor instabilities was provided at different operational speeds. Combining transient pressure data and PIV measurements, the time evolution of the complex flow patterns occurring at surge was reconstructed and a better insight into the bypass mechanism was achieved.

Guillou, Erwann; Gancedo, Matthieu; Gutmark, Ephraim; Mohamed, Ashraf

2012-09-01

81

Vacuum Planar Chromatography (VPC): A New Versatile Technique of Forced Flow Planar Chromatography  

Microsoft Academic Search

Taking the disadvantage of capillary development and vapor phase effects into account, new methods of forced flow development have appeared. The new process of chromatographic development described is part of forced flow system. It is the vacuum (Pressure lower than atmospheric pressure) which is implemented in order to achieve the chromatographic development by inhaling of the mobile phase through the

P. Delvordre; C. Regnault; E. Postaire

1992-01-01

82

Response to ``Comment on `Primary instability mechanisms on the magnetohydrodynamic boundary layer flow over a rotating disk subject to a uniform radial flow''' [Phys. Fluids 22, 029102 (2010)  

NASA Astrophysics Data System (ADS)

It was pointed out by Thess [``Comment on `Oblique axisymmetric stagnation flows in magnetohydrodynamics [Phys. Fluids 19, 114106 (2007)]','' Phys. Fluids 20, 069102 (2008)] by Amaouche that the model used in the paper "Primary instability mechanisms on the magnetohydrodynamic boundary layer flow over a rotating disk subject to a uniform radial flow" by Turkyilmazoglu [Phys. Fluids 21, 074103 (2009)] is incomplete since the electric potential was neglected. This point is clarified here, and the ambiguity present in the magnetohydrodynamic flow research of this kind among the fluid dynamic community is remedied. As a consequence, the qualitative validity of the results in the work of Turkyilmazoglu ["Primary instability mechanisms on the magnetohydrodynamic boundary layer flow over a rotating disk subject to a uniform radial flow," Phys. Fluids 21, 074103 (2009)] from both the physical and mathematical viewpoints is justified.

Turkyilmazoglu, M.

2010-02-01

83

Flow-Mediated Change in Viscoelastic Property of Radial Arterial Wall Measured by 22 MHz Ultrasound  

NASA Astrophysics Data System (ADS)

The endothelial dysfunction is considered to be an initial step in atherosclerosis. Additionally, it was reported that the smooth muscle, which constructs the media of the artery, changes its characteristics owing to atherosclerosis. Therefore, it is essential to develop a method of assessing the regional endothelial function and mechanical properties of the arterial wall. To evaluate the endothelial function, a conventional technique of measuring the transient change in the diameter of the brachial artery caused by flow-mediated dilation (FMD) after the release of avascularization is used. However, this method can not evaluate the mechanical properties of the wall. We previously developed a method for the simultaneous measurements of waveforms of radial strain and blood pressure in the radial artery. In this study, the viscoelasticity of the arterial wall was estimated from the measured stress-strain relationship using the least-squares method and the transient changes in the mechanical properties of the arterial wall ware revealed. From in vivo experimental results, the stress-strain relationship showed a hysteresis loop and viscoelasticity was estimated by the proposed method. The slope of the loop decreased owing to FMD, which resulted in the decrease in estimated elastic modulus. The increase in the area of the loop occurred after recirculation, which corresponds to the increase in the ratio of the loss modulus (depends on viscosity) to the elastic modulus when the Voigt model is assumed. In this study, the variance in estimates was evaluated by in vivo measurement for 10 min. The temporal decrease in static elasticity after recirculation due to FMD was much larger than the evaluated variance. These results show a potential of the proposed method for the thorough analysis of the transient change in viscoelasticity due to FMD.

Ikeshita, Kazuki; Hasegawa, Hideyuki; Kanai, Hiroshi

2009-07-01

84

Evaluation of Radial Flow Fluidized Filter (R3F) Followed by Microfiltration and Ultrafiltration Systems in Calimesa, California  

EPA Science Inventory

U.S. EPA coordinated a field study with South Mesa Water Utility to look for treatment alternatives for California State Project Water in the small community of Calimesa, California. EPA evaluated the performance of a system comprised of Radial Flow Fluidized Filtration (R3f) fo...

85

Influence of flow patterns on chromatographic efficiency in centrifugal partition chromatography.  

PubMed

Visualization of flow patterns in centrifugal partition chromatography (CPC) was performed with an asynchronous camera and a stroboscope triggered by the CPC rotor, allowing a channel to be selected and observed regardless of rotational speed. Three main types of flow states were noted as a function of rotational speed and flow-rate: jets stuck along channel walls, broken jets and atomization. Our observations emphasize the importance of Coriolis force on flow shape. Chromatographic efficiency was related to the dispersion of the mobile phase in the stationary phase. PMID:10720249

Marchal, L; Foucaul, A; Patissier, G; Rosant, J M; Legrand, J

2000-02-11

86

Experimental evaluation of connectivity influence on dispersivity under confined and unconfined radial convergent flow conditions  

NASA Astrophysics Data System (ADS)

Heterogeneity and connectivity have a significant impact on the fate and transport of contaminants due to the occurrence of formations with largest permeability than the surrounding geological materials, which can originate preferential pathways in groundwater system. These issues are usually addressed by tracer tests and a radial convergent (RC) flow setting is typically selected for convenience but more complicated for model interpretation than uniform flow transport. An experimental investigation was performed using RC tracer tests in a 3D intermediate scale physical model to illustrate the role of connected features on the estimation of dispersivity using the classical Sauty solution and the method of moments, under confined and unconfined aquifer conditions. The physical model consists of 26 piezometers located at difference distances from a constant-discharge central pumping well. The box is filled with gravel channels embedded in a sandy matrix and organized in different layers. Materials have been well characterized before and after the test. For the confined configuration, a silt layer was placed above the previous layers. Tracer tests were performed using potassium iodide solutions with concentration of 3•10-3 M and under a constant pumping flow rate of 0.05 L/s. To mimic a pulse injection in each piezometer we used syringes and pipes, whereas a probe allowed continuous measuring of tracer concentration. Average velocity and longitudinal dispersion coefficient were defined from the first and second central moment of the observed breakthrough curves for each piezometer (integrated over the outflow boundary of the domain) and using the classical curve matching from the Sauty's solution at different Péclet numbers. Results reveal in some cases that estimates of hydrodynamic parameters from the Sauty solution and the method of moments seem to be different. This is related to the different basic assumptions of the two methods applied, and especially because of the presence of preferential flow paths which have been found to strongly control the highest values of the average velocity at the source and affect the resulting longitudinal dispersion coefficient. This study showed additional lights on the impact of connectivity on transport and its role to obtain effective measurements of macrodispersion throughout the aquifer under RC transport. Reference: Fernàndez-Garcia D. et al. (2002) Convergent-flow tracer tests in heterogeneous media. Journal of Contaminant Hydrology 57 129-145. Fischer H. B. (1966) Longitudinal Dispersion in Laboratory and Natural Streams. Technical Rep. KH-R-12, California Institute of Technology, Pasadena, California. Gaspar E. (1987) Modern Trends in Tracer Hydrology, Volume II. CRC Press, Inc., Boca Raton, FL, USA.

Guzzi, Silvia; Molinari, Antonio; Fallico, Carmine; Pedretti, Daniele

2014-05-01

87

Flow Characterization and Dynamic Analysis of a Radial Compressor with Passive Method of Surge Control  

NASA Astrophysics Data System (ADS)

Due to recent emission regulations, the use of turbochargers for force induction of internal combustion engines has increased. Actually, the trend in diesel engines is to downsize the engine by use of turbochargers that operate at higher pressure ratio. Unfortunately, increasing the rotational speed tends to reduce the turbocharger radial compressor range of operation which is limited at low mass flow rate by the occurrence of surge. In order to extent the operability of turbochargers, compressor housings can be equipped with a passive surge control device also known as ported shroud. This specific casing treatment has been demonstrated to enhance surge margin with minor negative impact on the compressor efficiency. However, the actual working mechanisms of the bypass system remain not well understood. In order to optimize the design of the ported shroud, it is then crucial to identify the dynamic flow changes induced by the implementation of the device to control instabilities. Experimental methods were used to assess the development of instabilities from stable, stall and eventually surge regimes of a ported shroud centrifugal compressor. Systematic comparison was conducted with the same compressor design without ported shroud. Hence, the full pressure dynamic survey of both compressors' performance characteristics converged toward two different and probably interrelated driving mechanisms to the development and/or propagation of unsteadiness within each compressor. One related the pressure disturbances at the compressor inlet, and notably the more apparent development of perturbations in the non-ported compressor impeller, whereas the other was attributed to the pressure distortions induced by the presence of the tongue in the asymmetric design of the compressor volute. Specific points of operation were selected to carry out planar flow measurements. At normal working, both standard and stereoscopic particle imaging velocimetry (PIV) measurements were performed to calculate the instantaneous and mean velocity fields at the inlet of the compressor. At incipient and full surge, phase-locked PIV measurements were added. In this work, satisfying characterization of the compressor inlet flow instabilities was obtained at different operational speeds. Combining transient pressure data and PIV measurements, the time evolution of the complex flow patterns occurring at surge was reconstructed and a better insight into the bypass mechanisms was achieved.

Guillou, Erwann

88

The galactic habitable zone of the Milky Way and M31 from chemical evolution models with gas radial flows  

NASA Astrophysics Data System (ADS)

The galactic habitable zone is defined as the region with sufficient abundance of heavy elements to form planetary systems in which Earth-like planets could be born and might be capable of sustaining life, after surviving to close supernova explosion events. Galactic chemical evolution models can be useful for studying the galactic habitable zones in different systems. We apply detailed chemical evolution models including radial gas flows to study the galactic habitable zones in our Galaxy and M31. We compare the results to the relative galactic habitable zones found with `classical' (independent ring) models, where no gas inflows were included. For both the Milky Way and Andromeda, the main effect of the gas radial inflows is to enhance the number of stars hosting a habitable planet with respect to the `classical' model results, in the region of maximum probability for this occurrence, relative to the classical model results. These results are obtained by taking into account the supernova destruction processes. In particular, we find that in the Milky Way the maximum number of stars hosting habitable planets is at 8 kpc from the Galactic Centre, and the model with radial flows predicts a number which is 38 per cent larger than what was predicted by the classical model. For Andromeda we find that the maximum number of stars with habitable planets is at 16 kpc from the centre and that in the case of radial flows this number is larger by 10 per cent relative to the stars predicted by the classical model.

Spitoni, E.; Matteucci, F.; Sozzetti, A.

2014-05-01

89

Comment on ``Primary instability mechanisms on the magnetohydrodynamic boundary layer flow over a rotating disk subject to a uniform radial flow'' [Phys. Fluids 21, 074103 (2009)  

NASA Astrophysics Data System (ADS)

It is pointed out that the model used in the paper "Primary instability mechanisms on the magnetohydrodynamic boundary layer flow over a rotating disk subject to a uniform radial flow" by Turkyilmazoglu [Phys. Fluids 21, 074103 (2009)] is incomplete since the electric potential has been neglected. The results of the work should therefore be considered as qualitative until the analysis has been repeated using the correct set of equations.

Thess, André

2010-02-01

90

Kinetic behaviour in supercritical fluid chromatography with modified mobile phase for 5 ?m particle size and varied flow rates  

Microsoft Academic Search

After much development of stationary phase chemistry, in recent years the focus of many studies in HPLC has shifted to increase the efficiency and analysis speed. Ultra high pressure liquid chromatography (UHPLC) using sub-2?m particles, and high temperature liquid chromatography (HTLC), using temperatures above 100°C have received much attention. These new approaches allow the use of flow rates higher than

E. Lesellier; L. Fougere; Donald P. Poe

2011-01-01

91

Anatomical features that facilitate radial flow across growth rings and from xylem to cambium in Cryptomeria japonica  

PubMed Central

Background and Aims Although the lateral movement of water and gas in tree stems is an important issue for understanding tree physiology, as well as for the development of wood preservation technologies, little is known about the vascular pathways for radial flow. The aim of the current study was to understand the occurrence and the structure of anatomical features of sugi (Cryptomeria japonica) wood including the tracheid networks, and area fractions of intertracheary pits, tangential walls of ray cells and radial intercellular spaces that may be related to the radial permeability (conductivity) of the xylem. Methods Wood structure was investigated by light microscopy and scanning electron microscopy of traditional wood anatomical preparations and by a new method of exposed tangential faces of growth-ring boundaries. Key Results Radial wall pitting and radial grain in earlywood and tangential wall pitting in latewood provide a direct connection between subsequent tangential layers of tracheids. Bordered pit pairs occur frequently between earlywood and latewood tracheids on both sides of a growth-ring boundary. In the tangential face of the xylem at the interface with the cambium, the area fraction of intertracheary pit membranes is similar to that of rays (2·8 % and 2·9 %, respectively). The intercellular spaces of rays are continuous across growth-ring boundaries. In the samples, the mean cross-sectional area of individual radial intercellular spaces was 1·2 µm2 and their total volume was 0·06 % of that of the xylem and 2·07 % of the volume of rays. Conclusions A tracheid network can provide lateral apoplastic transport of substances in the secondary xylem of sugi. The intertracheid pits in growth-ring boundaries can be considered an important pathway, distinct from that of the rays, for transport of water across growth rings and from xylem to cambium. PMID:19258338

Kitin, Peter; Fujii, Tomoyuki; Abe, Hisashi; Takata, Katsuhiko

2009-01-01

92

A comparison of the calculated and experimental off-design performance of a radial flow turbine  

NASA Technical Reports Server (NTRS)

Off design aerodynamic performance of the solid version of a cooled radial inflow turbine is analyzed. Rotor surface static pressure data and other performance parameters were obtained experimentally. Overall stage performance and turbine blade surface static to inlet total pressure ratios were calculated by using a quasi-three dimensional inviscid code. The off design prediction capability of this code for radial inflow turbines shows accurate static pressure prediction. Solutions show a difference of 3 to 5 points between the experimentally obtained efficiencies and the calculated values.

Tirres, Lizet

1991-01-01

93

A Galerkin finite-element flow model to predict the transient response of a radially symmetric aquifer  

USGS Publications Warehouse

A computer program developed to evaluate radial flow of ground water, such as at a pumping well, recharge basin, or injection well, is capable of simulating anisotropic, inhomogenous, confined, or pseudo-unconfined (constant saturated thickness) conditions. Results compare well with those calculated from published analytical and model solutions. The program is based on the Galerkin finite-element technique. A sample model run is presented to illustrate the use of the program; supplementary material provides the program listing as well as a sample problem data set and output. From the text and other material presented, one can use the program to predict drawdowns from pumping and ground-water buildups from recharge in a radially symmetric ground-water system.

Reilly, Thomas E.

1984-01-01

94

A Laplace transform solution for tracer tests in a radially convergent flow field with upstream dispersion  

Microsoft Academic Search

When tracers are introduced into an injection borehole, noticeable concentration gradients at the injection well may cause a backward spreading of the initial plume during radially convergent tracer tests. Based on this concept a non-rigorous mathematical model is developed to estimate the effect of backward spreading. The injection well with an instantaneous slug input is treated as a mathematical source

Jui-Sheng Chen; Chen-Wuing Liu; Chia-Shyun Chen; Hun-Der Yen

1996-01-01

95

Final Technical Report: Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles  

SciTech Connect

The strong coupling between the different physical variables involved in the plasma transport phenomenon and the high complexity of its dynamics call for a model-based, multivariable approach to profile control where those predictive models could be exploited. The overall objective of this project has been to extend the existing body of work by investigating numerically and experimentally active control of unstable fluctuations, including fully developed turbulence and the associated cross-field particle transport, via manipulation of flow profiles in a magnetized laboratory plasma device. Fluctuations and particle transport can be monitored by an array of electrostatic probes, and Ex#2;B flow profiles can be controlled via a set of biased concentric ring electrodes that terminate the plasma column. The goals of the proposed research have been threefold: i- to develop a predictive code to simulate plasma transport in the linear HELCAT (HELicon-CAThode) plasma device at the University of New Mexico (UNM), where the experimental component of the proposed research has been carried out; ii- to establish the feasibility of using advanced model-based control algorithms to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles, iii- to investigate the fundamental nonlinear dynamics of turbulence and transport physics. Lehigh University (LU), including Prof. Eugenio Schuster and one full-time graduate student, has been primarily responsible for control-oriented modeling and model-based control design. Undergraduate students have also participated in this project through the National Science Foundation Research Experience for Undergraduate (REU) program. The main goal of the LU Plasma Control Group has been to study the feasibility of controlling turbulence-driven transport by shaping the radial poloidal flow profile (i.e., by controlling flow shear) via biased concentric ring electrodes.

Schuster, Eugenio

2014-05-02

96

[Application of turbulent flow chromatography in the analysis of biological samples].  

PubMed

The complexity of biological fluids makes the sample preparation necessary in the analytical process. The traditional techniques, such as liquid-liquid extraction and solid-phase extraction, are time-consuming and labor-intensive. Turbulent flow chromatography (TFC), as an on-line direct injection technique, possesses the advantages of reducing sample preparation steps and enabling the effective pre-concentration and clean-up of biological fluids. Therefore, it is a high-throughput and high-selectivity technique for biological sample pretreatment. In this review, the theory, advantages, characteristics and current status of TFC in bioanalysis are introduced and summarized. PMID:20556956

Liu, Peng; Zhou, Jianliang; An, Jingjing; Li, Ping

2010-02-01

97

Use of greatly-reduced gas flows in flow-modulated comprehensive two-dimensional gas chromatography-mass spectrometry.  

PubMed

The present research is specifically based on the use of greatly-reduced gas flows, in flow-modulator (FM) comprehensive two-dimensional gas chromatography systems. In particular, focus of the present research is directed to FM devices characterized by an accumulation stage, and a much briefer re-injection step. It has been widely accepted that the operation of such FM systems requires high gas flows (?20mL/min), to re-inject the gas-phase contents of sample (or accumulation) loops, onto the second column. On the contrary, it will be herein demonstrated that much lower gas flows (? 6-8mL/min) can efficiently perform the modulation step of re-injection. The possibility of using such improved operational conditions is given simply by a fine optimization of the processes of accumulation and re-injection. The application of lower gas flows not only means that second-dimension separations are carried out under better analytical conditions, but, even more importantly, greatly reduces problems which arise when using mass spectrometry (i.e., sensitivity and instrumental pumping capacity). PMID:25108766

Tranchida, Peter Q; Franchina, Flavio A; Dugo, Paola; Mondello, Luigi

2014-09-12

98

Indication of transverse radial flow in high-multiplicity proton-proton collisions at the Large Hadron Collider  

NASA Astrophysics Data System (ADS)

We analyze the measured spectra of ?±, K±, p(\\bar{p}) in proton-proton (pp) collisions at \\sqrt{s} = 0.9, 2.76 and 7 TeV in the light of blast-wave model to extract the transverse radial flow velocity and kinetic temperature at freeze-out for the system formed in pp collisions. The dependence of the blast-wave parameters on average charged particle multiplicity of event sample or the ‘centrality’ of collisions has been studied and compared with results of similar analysis in nucleus-nucleus (AA) and proton-nucleus (pA) collisions. We analyze the spectra of K_{s}^0, ?(\\bar{\\Lambda }) and ?- also to see the dependence of blast-wave description on the species of produced particles. Within the framework of the blast-wave model, the study reveals indication of collective behavior for high-multiplicity events in pp collisions at LHC. Strong transverse radial flow in high-multiplicity pp collisions and its comparison with that in pA and AA collisions match with predictions from a very recent theoretical work (Shuryak and Zahed 2013 arXiv:hep-ph/1301.4470) that addresses the conditions for applicability of hydrodynamics in pp and pA collisions.

Ghosh, Premomoy; Muhuri, Sanjib; Nayak, Jajati K.; Varma, Raghava

2014-03-01

99

Indication of transverse radial flow in high-multiplicity proton-proton collisions at the Large Hadron Collider  

E-print Network

We analyze the measured spectra of $\\pi^\\pm$, $K^\\pm$, $p$($\\bar p$) in $pp$ collisions at $\\sqrt {s}$ = 0.9, 2.76 and 7 TeV, in the light of blast-wave model to extract the transverse radial flow velocity and kinetic temperature at freeze-out for the system formed in $pp$ collisions. The dependency of the blast-wave parameters on average charged particle multiplicity of event sample or the `centrality' of collisions has been studied and compared with results of similar analysis in nucleus-nucleus ($AA$) and proton-nucleus ($pA$) collisions. We analyze the spectra of $K_{s}^0$, $\\Lambda$($\\bar \\Lambda$) and $\\Xi^-$ also to see the dependence of blast-wave description on the species of produced particles. Within the framework of the blast-wave model, the study reveals indication of collective behavior for high-multiplicity events in $pp$ collisions at LHC. Strong transverse radial flow in high multiplicity $pp$ collisions and its comparison with that in $pA$ and $AA$ collisions match with predictions from a very recent theoretical work [Shuryak and Zahed 2013 arXiv:1301.4470] that addresses the conditions for applicability of hydrodynamics in $pp$ and $pA$ collisions.

Premomoy Ghosh; Sanjib Muhuri; Jajati k. Nayak; Raghava Varma

2014-02-27

100

A radial flow microfluidic device for ultra-high-throughput affinity-based isolation of circulating tumor cells.  

PubMed

Circulating tumor cells (CTCs) are believed to play an important role in metastasis, a process responsible for the majority of cancer-related deaths. But their rarity in the bloodstream makes microfluidic isolation complex and time-consuming. Additionally the low processing speeds can be a hindrance to obtaining higher yields of CTCs, limiting their potential use as biomarkers for early diagnosis. Here, a high throughput microfluidic technology, the OncoBean Chip, is reported. It employs radial flow that introduces a varying shear profile across the device, enabling efficient cell capture by affinity at high flow rates. The recovery from whole blood is validated with cancer cell lines H1650 and MCF7, achieving a mean efficiency >80% at a throughput of 10 mL h(-1) in contrast to a flow rate of 1 mL h(-1) standardly reported with other microfluidic devices. Cells are recovered with a viability rate of 93% at these high speeds, increasing the ability to use captured CTCs for downstream analysis. Broad clinical application is demonstrated using comparable flow rates from blood specimens obtained from breast, pancreatic, and lung cancer patients. Comparable CTC numbers are recovered in all the samples at the two flow rates, demonstrating the ability of the technology to perform at high throughputs. PMID:25074448

Murlidhar, Vasudha; Zeinali, Mina; Grabauskiene, Svetlana; Ghannad-Rezaie, Mostafa; Wicha, Max S; Simeone, Diane M; Ramnath, Nithya; Reddy, Rishindra M; Nagrath, Sunitha

2014-12-10

101

A versatile cryo-focussing flow switching gas chromatography inlet for trace analysis of intractable compounds.  

PubMed

A wide variety of samples that can be analysed by gas chromatography do not lend themselves to the usual preparation of solvent extracts for split-splitless injections, and are best handled by purge and trap or equilibrium headspace sampling. A cryo-focussing, flow switching gas chromatography inlet system that handles different types of sample without the need for hardware changes has been prototyped. It provides excellent repeatability and linearity with liquid injections, purge and trap, and equilibrium headspace samples, in both split and splitless modes. The performance of the system was tested with sub-nanogram quantities of challenging analytes such as free carboxylic acids, alcohols, diols, phenols and aldehydes, and volatiles purged from contaminated soil, mammal faeces, a pesticide formulation, and a spice. Repeatability RSDs for peak areas were consistently below 11% and repeatabilities of retention times below 0.05%, independently of sample type (liquid or gas phase) and nature or quantity of compound. Regression coefficients of peak areas vs. quantity were typically ? 0.999 over two orders of magnitude ranges extending down to below 0.01 ng, also independently of sample and analyte. Limits of quantitation were robustly below 0.1-0.2 ng. Peak shapes and resolution are the same with use of the cryo-trap and flow switch as they are with conventional injections. Performance is robust to flow rate and, for most compounds, to trapping and desorption temperature. The cryo-trapping flow switching inlet's performance parameters match those of other sample introduction systems, and are achieved with sub-nanogram quantities of intractable analytes. PMID:22920301

Apps, Peter; Mmualefe, Lesego

2012-09-28

102

Analytical approximation of biodegradation rate for in situ bioremediation of groundwater under ideal radial flow conditions  

Microsoft Academic Search

We derive the long-term biodegradation rate of an organic contaminant (substrate) for an in situ bioremediation model with axisymmetric flow conditions. The model presumes that a nonsorbing electron acceptor is injected into a saturated homogeneous porous medium which initially contains a sorbing substrate and attached indigenous microorganisms. The derived analytical removal rate depends upon the injection flow rate, the initial

Shunji Oya; Albert J. Valocchi

1998-01-01

103

Inferring emplacement processes of radial dikes at Summer Coon volcano, Colorado, from geometry and AMS-derived magma flow directions  

NASA Astrophysics Data System (ADS)

Because population centers tend to cluster around the bases of volcanoes, the most distal flank eruptions can be the most hazardous. The emplacement mechanisms of radial dikes that commonly feed these extrusions are poorly understood. Consequently, we mapped and analyzed about 20 large silicic dikes which, along with hundreds of mafic dikes, are exposed in a radial pattern at Summer Coon, an eroded stratovolcano in the eastern San Juan Mountains, Colorado. In contrast to intrusions mapped at other centers, silicic dikes at Summer Coon tend to thicken with increasing radial distance. Shallower burial depths and decreasing elastic moduli away from the center of the volcano cause an increase in the dike driving pressure, and are the most likely sources of the observed teardrop form. All silicic dikes are broken into en echelon segments dominated by right-stepping offsets. Segment geometries around the volcano do not agree with previously proposed dike segmentation mechanisms including stress field rotation, intrusion into preexisting fractures, and variations in host rock properties. Flow directions determined from measurements of anisotropy of magnetic susceptibility (AMS) at 33 sites on two different dikes suggest that offsets near the center of the volcano form when magma fills echelon fractures that opened in front of the propagating dike. Distal segments probably form by the same mechanism, however both segment tips may propagate due to higher driving pressures far from the center of the volcano. Observations from Summer Coon suggest that radial dikes rise sub-vertically from depth beneath the volcano and then propagate laterally away from the center of the volcano along a neutral buoyancy surface between the base of the edifice (which is composed of low-density volcanic rocks) and the higher-density basement. The dike will thicken with increasing radial distance, favoring more voluminous eruptions at lower elevations. Future detailed geodetic studies of active stratovolcanoes (for instance, InSAR measurements of deformation at South Sister Volcano in Oregon by Wicks and others, in review, GRL), combined with additional AMS studies of dikes from eroded volcanoes may help confirm these inferred emplacement paths.

Poland, M. P.; Fink, J. H.

2001-12-01

104

Presentation of the MERC work-flow for the computation of a 2D radial reflector in a PWR  

SciTech Connect

This paper presents a work-flow for computing an equivalent 2D radial reflector in a pressurized water reactor (PWR) core, in adequacy with a reference power distribution, computed with the method of characteristics (MOC) of the lattice code APOLLO2. The Multi-modelling Equivalent Reflector Computation (MERC) work-flow is a coherent association of the lattice code APOLLO2 and the core code COCAGNE, structured around the ADAO (Assimilation de Donnees et Aide a l'Optimisation) module of the SALOME platform, based on the data assimilation theory. This study leads to the computation of equivalent few-groups reflectors, that can be spatially heterogeneous, which have been compared to those obtained with the OPTEX similar methodology developed with the core code DONJON, as a first validation step. Subsequently, the MERC work-flow is used to compute the most accurate reflector in consistency with all the R and D choices made at Electricite de France (EDF) for the core modelling, in terms of number of energy groups and simplified transport solvers. We observe important reductions of the power discrepancies distribution over the core when using equivalent reflectors obtained with the MERC work-flow. (authors)

Clerc, T.; Hebert, A. [Institut de Genie Nucleaire, Station Centre-Ville, Montreal, QC, H3C 3A7 (Canada); Leroyer, H.; Argaud, J. P.; Poncot, A.; Bouriquet, B. [Electricite de France, R and D, SINETICS, 1 Av. du General de Gaulle, 92141, Clamart (France)

2013-07-01

105

Investigation of subsonic and supersonic flow in a radial inflow compressor  

E-print Network

Patent Office, 3305165, Feb. 21, 1967. 3. Hamrick, Joseph T. , Gimsburg, Amrose, Osborne, Walter, Method. of analysis for compressible flow through mixed flow centrifugal impellers of ar'oitrary design. NACA Rep. 1082, 1952. 4. Stanitz, John D.... and Prian, Vasily D. , A rapid approximation method for determining velocity distribution on impeller blades of centrifugal compressors. NACA TN 2421. 5. Stockman, N. 0. and Kramer, J. L. , Method fo" desigr. of punp impellers using a high speed digital...

Bale, Yadiyurappa Siddaveerasetty

1970-01-01

106

Multigrid-accelerated Navier-Stokes computations of the 3D flow in axial and radial flow turbomachinery  

NASA Astrophysics Data System (ADS)

The paper describes the implementation of a three-dimensional Navier-Stokes solver within the framework of a multigrid strategy. The ability of multigrid to improve and sustain code performance over a range of mesh sizes and a variety of difficult flow problems is investigated. The code is applied to the study of the shock-induced boundary layer separation on a channel hump, the flow in a two-dimensional cascade of compressor blades, the secondary flow development in a linear cascade of gas turbine blades, and the Eckardt backswept centrifugal impeller. In each case, multigrid leads to significantly improved performance.

Dawes, W. N.

107

Radial hopper flow prediction using a constitutive model with microstructure evolution  

E-print Network

We present theoretical predictions of granular flow in a conical hopper based on a continuum theory employing a recently-developed constitutive model with microstructure evolution by Sun and Sundaresan [1]. The model is developed for strain rate-independent granular flows. The closures for the pressure and the macroscopic friction coefficient are linked to microstructure through evolution equations for the coordination number and fabric. The material constants in the model are functions of particle-level properties. A salient prediction is the variable stress ratio along the flow direction, in contrast to the constant ratio employed in some widely-used plasticity theories, but supported by results obtained from discrete element simulations. The model permits direct interrogation of the influence of particle-particle friction as well as normal-stress differences on the stress distribution and discharge rate. Increasing particle friction leads to higher stress ratios, but lower normal stress and flow rates, while considering normal-stress differences results in the opposite effects.

Jin Sun; Sankaran Sundaresan

2012-07-07

108

Distributed control of reactive power flow in a radial distribution circuit with high photovoltaic penetration  

SciTech Connect

We show how distributed control of reactive power can serve to regulate voltage and minimize resistive losses in a distribution circuit that includes a significant level of photovoltaic (PV) generation. To demonstrate the technique, we consider a radial distribution circuit with a single branch consisting of sequentially-arranged residential-scale loads that consume both real and reactive power. In parallel, some loads also have PV generation capability. We postulate that the inverters associated with each PV system are also capable of limited reactive power generation or consumption, and we seek to find the optimal dispatch of each inverter's reactive power to both maintain the voltage within an acceptable range and minimize the resistive losses over the entire circuit. We assume the complex impedance of the distribution circuit links and the instantaneous load and PV generation at each load are known. We compare the results of the optimal dispatch with a suboptimal local scheme that does not require any communication. On our model distribution circuit, we illustrate the feasibility of high levels of PV penetration and a significant (20% or higher) reduction in losses.

Chertkov, Michael [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory; Backhaus, Scott [Los Alamos National Laboratory; Sule, Petr [NEW MEXICO CONSORTIUM

2009-01-01

109

Low flow high-performance liquid chromatography solvent delivery system designed for tandem capillary liquid chromatography-mass spectrometry  

Microsoft Academic Search

A solvent delivery system is described that is designed to increase the efficiency of liquid chromatography-mass spectrometry\\u000a (LC\\/MS) analyses. Gradients formed by using two low pressure syringe pumps are stored in a length of narrow bore tubing (gradient\\u000a loop) mounted on a standard high pressure switching valve. The preformed gradient is pushed through the column by using a\\u000a high pressure

M. T. Davis; D. C. Stahl; T. D. Lee

1995-01-01

110

Discrepancy Between the Theoretical Plate Number (N) and Peak Resolution (Rs) for Optimizing the Flow Rate in Countercurrent Chromatography  

Microsoft Academic Search

This paper deals with a problem in optimizing the flow rate of the mobile phase in countercurrent chromatography (CCC), A set of data including theoretical plate number (N), resolution factor (Rs), % retention, etc. are obtained from the separation of three indole auxins in a two-phase solvent system of n-hexane \\/ ethyl acetate \\/ methanol \\/ water (1:1:1:1) by applying

Hisao Oka; Yoshitomo Ikai; Junko Hayakawa; Ken-Ichi Harada; Kazuko Nagase; Makoto Suzuki; Hiroyuki Nakazawa; Yoichiro Ito

1992-01-01

111

Optimal design of high damping force engine mount featuring MR valve structure with both annular and radial flow paths  

NASA Astrophysics Data System (ADS)

This paper focuses on the optimal design of a compact and high damping force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high damping force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum damping force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the ‘lockup’ problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting damping force and power consumption.

Nguyen, Q. H.; Choi, S. B.; Lee, Y. S.; Han, M. S.

2013-11-01

112

Weak Radial Artery Pulse  

PubMed Central

We present an 11year-old boy with a weak right radial pulse, and describe the successful application of vascular ultrasound to identify the ulnar artery dominance and a thin right radial artery with below normal Doppler flow velocity that could explain the discrepancy. The implications of identifying this anomaly are discussed. PMID:22375269

Venugopalan, Poothirikovil; Sivakumar, Puthuval; Ardley, Robert G.; Oates, Crispian

2012-01-01

113

THE COMPACTNESS OF FRONT TRACKING FOR CHROMATOGRAPHY ELECTROPHORESIS AND INCOMPRESSIBLE MULTIPHASE FLOW  

E-print Network

THE COMPACTNESS OF FRONT TRACKING FOR CHROMATOGRAPHY ELECTROPHORESIS AND INCOMPRESSIBLE MULTIPHASE. SUMMARY An analysis of the equations of chromatography from the point of view of hyperbolic conservation a subsequence converging to a weak solution of the chromatography equations, with no restriction on the size

114

Analysis of a complex polysaccharide (gum arabic) by multi-angle laser light scattering coupled on-line to size exclusion chromatography and flow field flow fractionation  

Microsoft Academic Search

The heterogeneous polysaccharide gum arabic has been characterized using size exclusion chromatography (SEC) and flow field flow fractionation (F4) coupled on-line to multi-angle laser light scattering (MALLS). Two distinct populations have been shown. About 80% of the material consist of highly branched arabinogalactan (AG) units. The rest is mainly composed of heterogeneous arabinogalactan–protein complex (AGP) of high molecular weight. The

L. Picton; I. Bataille; G. Muller

2000-01-01

115

Flow rate dependent extra-column variance from injection in capillary liquid chromatography.  

PubMed

Efficiency and resolution in capillary liquid chromatography (LC) can be significantly affected by extra-column band broadening, especially for isocratic separations. This is particularly a concern in evaluating column bed structure using non-retained test compounds. The band broadening due to an injector supplied with a commercially available capillary LC system was characterized from experimental measurements. The extra-column variance from the injection valve was found to have an extra-column contribution independent of the injection volume, showing an exponential dependence on flow rate. The overall extra-column variance from the injection valve was found to vary from 34 to 23nL. A new mathematical model was derived that explains this exponential contribution of extra-column variance on chromatographic performance. The chromatographic efficiency was compromised by ?130% for a non-retained analyte because of injection valve dead volume. The measured chromatographic efficiency was greatly improved when a new nano-flow pumping system with integrated injection valve was used. PMID:25591400

Aggarwal, Pankaj; Liu, Kun; Sharma, Sonika; Lawson, John S; Dennis Tolley, H; Lee, Milton L

2015-02-01

116

A novel micropreconcentrator employing a laminar flow patterned heater for micro gas chromatography  

NASA Astrophysics Data System (ADS)

A simple micromachined process based on one photomask is developed for a novel micropreconcentrator (µPCT) used in a micro gas chromatograph (µGC). Unique thick silver heating microstructures with a high surface area for microheater of µPCT are fabricated by combining the microfluidic laminar flow technique and the Tollens’ reaction within a microchannel. Silver deposition using this laminar flow patterning technique provides a higher deposition rate and easier microfabrication compared to conventional micromachined technologies for thick metal microstructures (>200 µm). An amorphous and porous carbon film that functions as an adsorbent is grown on microheaters inside the microchannel. The µPCT can be heated to >300 °C rapidly by applying a constant electrical power of ˜1 W with a heating rate of 10 °C s-1. Four volatile organic compounds, acetone, benzene, toluene and xylene, are collected through the proposed novel µPCTs and separated successfully using a 17 m long gas chromatography column. The peak widths at half height (PWHHs) of the four compounds are relatively narrow (<6 s), and the minimum PWHH of 3.75 s is obtained for acetone. The preconcentration factors are >38 000 for benzene and toluene.

Tian, W.-C.; Wu, T. H.; Lu, C.-J.; Chen, W. R.; Sheen, H. J.

2012-06-01

117

Continuous flow ion mobility separation with mass spectrometric detection using a nano-radial differential mobility analyzer at low flow rates.  

PubMed

We describe a hybrid mass-mobility instrument in which a continuous-flow ion mobility classifier is used as a front-end separation device for mass spectrometric analysis of ions generated with an electrospray ionization source. Using nitrogen as a carrier gas, the resolving power of the nano-radial differential mobility analyzer (nRDMA) for nanometer-sized ions is 5-7 for tetraalkylammonium ions. Data are presented demonstrating the ability of the system to resolve the different aggregation and charge states of tetraalkylammonium ions and protonated peptides using a quadrupole ion trap (QIT) mass spectrometer to analyze the mobility-classified ions. Specifically, data are presented for the two charge states of the decapeptide Gramicidin S. A key feature of the new instrument is the ability to continuously transmit ions with specific mobilities to the mass spectrometer for manipulation and analysis. PMID:23544674

Brunelli, N A; Neidholdt, E L; Giapis, K P; Flagan, R C; Beauchamp, J L

2013-05-01

118

Possible Evidence for Radial Flow of Heavy Mesons in d+Au Collisions  

E-print Network

Recent measurements of particle correlations and the spectra of hadrons at both RHIC and the LHC are suggestive of hydrodynamic behavior in very small collision systems (p+Pb, d+Au and p+p collisions). The measurements are both qualitatively and quantitatively similar to what is seen in central heavy ion collisions where low viscosity hot nuclear matter is formed. While light quarks and gluons are thought to make up the bulk matter, one of the most surprising results in heavy ion collisions is that charm quarks also have a large $v_2$, suggesting that they too participate in the matter. Measurements of the transverse momentum spectra of electrons from the decay of $D$ and $B$ mesons in d+Au show an enhancement in central collisions relative to p+p. We employ the blast-wave model to determine if the flow of heavy quarks in d+Au and p+Pb data is able to explain the enhancement observed in the data. We find a reasonable description of the data with blast-wave parameters extracted from fits to the light hadron spectra, suggesting hydrodynamics as a possible explanation.

Anne M. Sickles

2014-03-27

119

A flexible loop-type flow modulator for comprehensive two-dimensional gas chromatography.  

PubMed

The present investigation is focused on a simple flow modulator (FM), for comprehensive two-dimensional gas chromatography (GC×GC). The interface is stable at high temperatures, and consists of a metallic disc (located inside the GC oven) with seven ports, which are connected to an auxiliary pressure source via two branches, to the first and second dimension, to a waste branch (linked to a needle valve) and to an exchangeable modulation loop (2 ports). The ports are connected via micro-channels, etched on one of the inner surfaces of the disc. Modulation is achieved using a two-way electrovalve, connected on one side to the additional pressure source, and to the two metal branches, on the other. An FM enantio-GC×polar-GC method (using a flame ionization detector) was optimized (a 40-?L loop was employed), for the analysis of essential oils. As an example, an application on spearmint oil is shown; the method herein proposed was subjected to validation. Finally, an FM GC×GC diesel experiment was carried out, using an apolar-polar column combination, to demonstrate the effectiveness of the modulator in the analysis of a totally different sample-type. PMID:21256493

Tranchida, Peter Quinto; Purcaro, Giorgia; Visco, Alessandro; Conte, Lanfranco; Dugo, Paola; Dawes, Peter; Mondello, Luigi

2011-05-27

120

A variant of circular thin-layer chromatography with a forced flow of the mobile phase produced by an electroosmotic pump  

NASA Astrophysics Data System (ADS)

A new variant of circular thin-layer chromatography (TLC) with a closed sorption layer in which a forced flow of the mobile phase was produced and controlled by an external electroosmotic pump placed at the center of a TLC plate was suggested. It was shown experimentally that the method operated properly and could be used in planar chromatography.

Berezkin, V. G.; Nekhoroshev, G. A.

2007-11-01

121

Determination of finasteride in human plasma by liquid chromatography–electrospray ionization tandem mass spectrometry with flow rate gradient  

Microsoft Academic Search

In this study, an attempt was made to describe and validate liquid chromatography–electrospray ionization tandem mass spectrometry\\u000a as a fast, sensitive and reproducible method for determining finasteride in human plasma. Finasteride and internal standard\\u000a (pantoprazole) were extracted by liquid–liquid extraction using methyl tert-butyl ether. Separation was performed by using\\u000a a flow rate gradient on a reverse phase C18 column at

Lihua YuanMeijuan; Meijuan Ding; Jing Ma; Jinhui Xu; Xiaoli Wu; Jing Feng; Fei Shen; Xuemin Zhou

2011-01-01

122

Analysis of endocrine disrupters and related compounds in sediments and sewage sludge using on-line turbulent flow chromatography-liquid chromatography-tandem mass spectrometry.  

PubMed

A novel fully automated method based on dual column switching using turbulent flow chromatography followed by liquid chromatography coupled to tandem mass spectrometry (TFC-LC-MS/MS) was applied for the determination of endocrine disruptors (EDCs) and related compounds in sediment and sewage sludge samples. This method allows the unequivocal identification and quantification of the most relevant environmental EDCs such as natural and synthetic estrogens and their conjugates, antimicrobials, parabens, bisphenol A (BPA), alkylphenolic compounds, benzotriazoles, and organophosphorus flame retardants, minimizing time of analysis and alleviating matrix effects. Applying this technique, after the extraction of the target compounds by pressurized liquid extraction (PLE), sediment and sewage sludge extracts were directly injected to the chromatographic system and the analytes were concentrated into the clean-up loading column. Using six-port switching system, the analytes were transferred to the analytical column for subsequent detection by MS-MS (QqQ). In order to optimize this multiplexing system, a comparative study employing six types of TurboFlow™ columns, with different chemical modifications, was performed to achieve the maximum retention of analytes and best elimination of matrix components. Using the optimized protocol low limits of quantification (LOQs) were obtained ranging from 0.0083 to 1.6 ng/g for sediment samples and from 0.10 to 125 ng/g for sewage sludge samples (except for alkylphenol monoethoxylate). The method was used to evaluate the presence and fate of target EDCs in the Ebro River which is the most important river in Spain with intensive agricultural and industrial activities in the basin that contribute to deteriorating soil and water quality. PMID:24909438

Gorga, Marina; Insa, Sara; Petrovic, Mira; Barceló, Damià

2014-07-25

123

Radial and circumferential flow surveys at the inlet and exit of the Space Shuttle Main Engine High Pressure Fuel Turbine Model  

Microsoft Academic Search

The main objective of this test was to obtain detailed radial and circumferential flow surveys at the inlet and exit of the SSME High Pressure Fuel Turbine model using three-hole cobra probes, hot-film probes, and a laser velocimeter. The test was designed to meet several objectives. First, the techniques for making laser velocimeter, hot-film probe, and cobra probe measurements in

S. T. Hudson; W. J. Bordelon Jr.; A. W. Smith; N. Ramachandran

1995-01-01

124

Reducing NO(x) emissions from a nitric acid plant of domestic petrochemical complex: enhanced conversion in conventional radial-flow reactor of selective catalytic reduction process.  

PubMed

The nitric acid plant of a domestic petrochemical complex is designed to annually produce 56,400 metric tons (based on 100% nitric acid). In the present work, radial-flow spherical bed reactor (RFSBR) for selective catalytic reduction of nitric oxides (NO(x)) from the stack of this plant was modelled and compared with the conventional radial-flow reactor (CRFR). Moreover, the proficiency of a radial-flow (water or nitrogen) membrane reactor was also compared with the CRFR which was found to be inefficient at identical process conditions. In the RFSBR, the space between the two concentric spheres is filled by a catalyst. A mathematical model, including conservation of mass has been developed to investigate the performance of the configurations. The model was checked against the CRFR in a nitric acid plant located at the domestic petrochemical complex. A good agreement was observed between the modelling results and the plant data. The effects of some important parameters such as pressure and temperature on NO(x) conversion were analysed. Results show 14% decrease in NO(x) emission annually in RFSBR compared with the CRFR, which is beneficial for the prevention of NO(x) emission, global warming and acid rain. PMID:24527652

Abbasfard, Hamed; Hashemi, Seyed Hamid; Rahimpour, Mohammad Reza; Jokar, Seyyed Mohammad; Ghader, Sattar

2013-01-01

125

The solution-adaptive numerical simulation of the 3D viscous flow in the serpentine coolant passage of a radial inflow turbine blade  

NASA Astrophysics Data System (ADS)

This paper describes the application of a solution-adaptive, three-dimensional Navier-Stokes solver to the problem of the flow in turbine internal coolant passages. First the variation of Nusselt number in a cylindrical, multi-ribbed duct is predicted and found to be in acceptable agreement with experimental data. Then the flow is computed in the serpentine coolant passage of a radial inflow turbine including modeling the internal baffles and pin fins. The aerodynamics of the passage, particularly that associated with the pin fins, is found to be complex. The predicted heat transfer coefficients allow zones of poor coolant penetration and potential hot spots to be identified.

Dawes, W. N.

1992-06-01

126

Improving quantification using curtain flow chromatography columns in the analysis of labile compounds: A study on amino acids.  

PubMed

The performance of curtain flow chromatography column technology with MS detection was evaluated for the analysis of labile compounds. The curtain flow column design allows for separations that are faster and/or more sensitive than conventional columns, depending on how exactly the curtain flow column is configured. For example, when mass spectral detection is employed, the curtain flow column can yield separations that are 5-times faster than conventional columns when the curtain flow and the conventional columns have the same internal diameter. Or when the internal diameter of the conventional column is reduced in order to yield the same analytical through-put as the curtain flow column, the sensitivity on the curtain flow column can be as much as 66-fold higher than the conventional column. As a consequence of the higher analytical through-put less standardization is required in the analysis of labile compounds because less sample degradation is apparent. Consequently the sample integrity is preserved yielding data of a higher quality. PMID:25497579

Kocic, D; Pereira, L; Edge, T; Ritchie, H; Conlan, X A; Shalliker, R A

2015-01-01

127

Oxidation of element 102, nobelium, with flow electrolytic column chromatography on an atom-at-a-time scale.  

PubMed

We report here on the successful oxidation of element 102, nobelium (No), on an atom-at-a-time scale in 0.1 M alpha-hydroxyisobutyric acid (alpha-HIB) solution using a newly developed technique, flow electrolytic column chromatography. It is found that the most stable ion, No(2+), is oxidized to No(3+) within 3 min and that the oxidized No complex with alpha-HIB holds the trivalent state in the column above an applied potential of 1.0 V. PMID:19514720

Toyoshima, Atsushi; Kasamatsu, Yoshitaka; Tsukada, Kazuaki; Asai, Masato; Kitatsuji, Yoshihiro; Ishii, Yasuo; Toume, Hayato; Nishinaka, Ichiro; Haba, Hiromitsu; Ooe, Kazuhiro; Sato, Wataru; Shinohara, Atsushi; Akiyama, Kazuhiko; Nagame, Yuichiro

2009-07-01

128

Impact of the BEA zeolite morphology on isobutane adsorption followed by Reversed-Flow Inverse Gas Chromatography.  

PubMed

The mass transfer phenomena of isobutane (i-C4) were investigated at 343K on three protonic BEA zeolites. Defined by their crystallites sizes and degrees of aggregation, these samples were characterized by Reversed-Flow Inverse Gas Chromatography (RF-GC). This simple technique, used in conjunction with numerical computation, allowed the determination of physicochemical quantities like local monolayer capacities, probability density functions and diffusion coefficients in a time-resolved way. This study enabled to conclude that the effective diffusion coefficient was affected by the size of the zeolite agglomerate whereas the surface diffusion depended on the zeolite crystallite size. PMID:22964049

Batalha, N; Soualah, A; Pinard, L; Pouilloux, Y; Lemos, F; Belin, T

2012-10-19

129

Packing of large-scale chromatography columns with irregularly shaped glass based resins using a stop-flow method  

PubMed Central

Rigid chromatography resins, such as controlled pore glass based adsorbents, offer the advantage of high permeability and a linear pressure-flow relationship irrespective of column diameter which improves process time and maximizes productivity. However, the rigidity and irregularly shaped nature of these resins often present challenges in achieving consistent and uniform packed beds as formation of bridges between resin particles can hinder bed consolidation. The standard flow-pack method when applied to irregularly shaped particles does not yield well-consolidated packed beds, resulting in formation of a head space and increased band broadening during operation. Vibration packing methods requiring the use of pneumatically driven vibrators are recommended to achieve full packed bed consolidation but limitations in manufacturing facilities and equipment may prevent the implementation of such devices. The stop-flow packing method was developed as an improvement over the flow-pack method to overcome these limitations and to improve bed consolidation without the use of vibrating devices. Transition analysis of large-scale columns packed using the stop-flow method over multiple cycles has shown a two- to three-fold reduction of change in bed integrity values as compared to a flow-packed bed demonstrating an improvement in packed bed stability in terms of the height equivalent to a theoretical plate (HETP) and peak asymmetry (As). PMID:25080096

Siu, Sun Chau; Chia, Celeste; Mok, Yanglin; Pattnaik, Priyabrata

2014-01-01

130

Minimizing ultraviolet noise due to mis-matches between detector flow cell and post column mobile phase temperatures in supercritical fluid chromatography: effect of flow cell design.  

PubMed

A mis-match between the post-column mobile phase temperature and the UV detector flow cell temperature can cause significant UV noise in supercritical fluid chromatography (SFC). Deviations as little as 5 °C can increase noise as much as 5 times, making the detector unsuited for trace analysis. Two approaches were used to minimize this noise. When a flow cell was in direct thermal contact (metal on metal) with the detector optical bench, the mobile phase temperature was actively controlled to the measured flow cell temperature, by using one of the heat exchangers (HX) in the column compartment. However, with some older, but still widely used flow cell designs, this required repeated, hourly monitoring of the flow cell temperature and repeated manual adjustment of the heat exchanger temperature, due to thermal drift. Flow cell design had a strong influence on susceptibility to this thermally induced noise. Thermally insulating the flow cell from the optical bench made some cells much less susceptible to such thermally induced noise. Five different flow cells, some insulated, some un-insulated, were evaluated. Most had a truncated conical flow path, but one had a cylindrical flow path. Using either approach, the ASTM noise, with a 10mm, 13 ?L conical flow cell, could be optimized to ?0.007 mAU at 2.5 Hz, in SFC, which is very near the 0.006 mAU manufacturer's specification for HPLC. The insulated version of this flow cell required far less optimization, compared to the un-insulated version. At 150 bar, an experimental 3mm, 2 ?L flow cell, with only one side insulated, yielded noise slightly too high (?0.16-0.18 mAU) for trace analysis, at 80 Hz. However, at 200 bar, noise at 80 Hz was <0.06 mAU, which should allow quantification of a 1 mAU tall trace component with a signal to noise ratio (S/N) >10. Even partially un-insulated, this flow cell design was much less susceptible to thermally induced noise. Further insulating this flow cell design failed to improve performance. PMID:25189330

Berger, Terry A

2014-10-17

131

Stress-Field Modeling and Pressure Drop Prediction for Slug-Flow Pneumatic Conveying in an Aerated Radial Stress Chamber  

Microsoft Academic Search

Slug-flow pneumatic conveying is a full-bore mode of flow within the dense-phase flow regime where bulk materials are transported in the form of slugs at conveying speeds below saltation velocity. The mechanism of slug-flow pneumatic conveying consists of the particles being picked up from the stationary bed in front of a moving slug while the same amount of material is

T. KRULL; M. G. JONES; S. KEYS

2004-01-01

132

Influence of heat and mass transfer, initial stress and radially varying magnetic field on the peristaltic flow in an annulus with gravity field  

NASA Astrophysics Data System (ADS)

In this paper, the effects of both initial stress, radially varying and gravity field on the peristaltic flow of an incompressible MHD Newtonian fluid in a vertical annulus have been studied under the assumption of long wavelength and low-Reynolds number. The analytical solution has been derived for the temperature, concentration and velocity. The results for velocity, concentration and temperature obtained in the analytical form have been evaluated numerically and discussed briefly. The effect of the non-dimensional wave amplitude, the coefficient of viscosity, Sort number, Schmidt number, initial stress, gravitational field and the dimensionless time-mean flow in the wave frame are analyzed theoretically and computed numerically. The expressions for pressure rise, temperature, concentration field, velocity and pressure gradient are sketched for various embedded parameters and interpreted. Numerical results are given and illustrated graphically in each case considered. Comparison was made with the results obtained in the presence and absence of initial stress and gravitational field.

Abd-Alla, A. M.; Abo-Dahab, S. M.; El-Shahrany, H. D.

2014-08-01

133

Online spectrophotometric determination of Fe(II) and Fe(III) by flow injection combined with low pressure ion chromatography.  

PubMed

A simple and new low pressure ion chromatography combined with flow injection spectrophotometric procedure for determining Fe(II) and Fe(III) was established. It is based on the selective adsorption of low pressure ion chromatography column to Fe(II) and Fe(III), the online reduction reaction of Fe(III) and the reaction of Fe(II) in sodium acetate with phenanthroline, resulting in an intense orange complex with a suitable absorption at 515nm. Various chemical (such as the concentration of colour reagent, eluant and reductive agent) and instrumental parameters (reaction coil length, reductive coil length and wavelength) were studied and were optimized. Under the optimum conditions calibration graph of Fe(II)/Fe(III) was linear in the Fe(II)/Fe(III) range of 0.040-1.0mg/L. The detection limit of Fe(III) and Fe(II) was respectively 3.09 and 1.55?g/L, the relative standard deviation (n=10) of Fe(II) and Fe(III) 1.89% and 1.90% for 0.5mg/L of Fe(II) and Fe(III) respectively. About 2.5 samples in 1h can be analyzed. The interfering effects of various chemical species were studied. The method was successfully applied in the determination of water samples. PMID:25523043

Chen, Shujuan; Li, Nan; Zhang, Xinshen; Yang, Dongjing; Jiang, Heimei

2015-03-01

134

Conformational transitions of macromolecules in an eluent flow and their manifestation in the chromatography of polymers  

NASA Astrophysics Data System (ADS)

The behaviour of macromolecules in a free eluent flow, in a confined space, and in a flow passing through a pore system is considered. It is shown that the behaviour of macromolecules can be described by different theories such as the De Gennes theory and the theory of A DiMarzio and C M Guttman. Specific features of chromatographic fractionation and separation processes with the use of membranes formed from ultrahigh-molecular-mass polymers, which are widely used as constructional materials, are discussed. To account for these features, theoretical models considering conformational transitions of macromolecules in the eluent flow and taking into account possible degradation of macromolecules under the influence of the flow are applied. The current state of theoretical and experimental studies of the behaviour of macromolecules in a fluid flow is surveyed. The bibliography includes 152 references.

Kurganov, A. A.; Kanateva, A. Yu; Orekhov, V. A.

2014-07-01

135

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

PubMed

We describe a new approach to multiplex detection for HPLC, exploiting parallel segmented outlet flow - a new column technology that provides pressure-regulated control of eluate flow through multiple outlet channels, which minimises the additional dead volume associated with conventional post-column flow splitting. Using three detectors: one UV-absorbance and two chemiluminescence systems (tris(2,2'-bipyridine)ruthenium(III) and permanganate), we examine the relative responses for six opium poppy (Papaver somniferum) alkaloids under conventional and multiplexed conditions, where approximately 30% of the eluate was distributed to each detector and the remaining solution directed to a collection vessel. The parallel segmented outlet flow mode of operation offers advantages in terms of solvent consumption, waste generation, total analysis time and solute band volume when applying multiple detectors to HPLC, but the manner in which each detection system is influenced by changes in solute concentration and solution flow rates must be carefully considered. PMID:24216209

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

2013-11-25

136

Fraction Collection from Capillary Liquid Chromatography and Off-line Electrospray Ionization Mass Spectrometry using Oil Segmented Flow  

PubMed Central

Off-line analysis and characterization of samples separated by capillary liquid chromatography (LC) has been problematic using conventional approaches to fraction collection. We demonstrate collection of nanoliter fractions by forming plugs of effluent from a 75 ?m inner diameter LC column segmented by an immiscible oil such as perfluorodecalin. The plugs are stored in tubing that can then be used to manipulate the samples. Off-line electrospray ionization mass spectrometry (ESI-MS) was used to characterize the samples. ESI-MS was performed by directly pumping the segmented plugs into a nanospray emitter tip. Critical parameters including the choice of oils, ESI voltage, and flow rates that allows successful direct infusion analysis were investigated. Best signals were obtained under conditions in which the oil did not form an electrospray but was siphoned away from the tip. Off-line analysis showed preservation of the chromatogram with no loss of resolution. The method was demonstrated to allow changes in flow rate during the analysis. Specifically, decreases in flow rate were used to allow extended MS analysis time on selected fractions, similar to “peak parking”. PMID:20491430

Li, Qiang; Pei, Jian; Song, Peng; Kennedy, Robert T.

2010-01-01

137

Determination of lipoic acid by flow-injection and high-performance liquid chromatography with chemiluminescence detection.  

PubMed

A new flow-injection (FI) and high performance liquid chromatography (HPLC) with chemiluminescence detection method has been proposed for the determination of ?-lipoic acid (LA). The assay is based on the measurement of chemiluminescence (CL) produced during the reaction of ?-lipoic acid with potassium permanganate in a sodium hexametaphosphate medium (pH 3). This reaction is accompanied by a weak CL, which is greatly increased in the presence of a formaldehyde solution. The proposed FI method allows the determination of LA over the range: 0.5-20?gmL(-1) with LOD 4×10(-3)?gmL(-1). An introduction of HPLC into the flow manifold improves selectivity of the method and allows the determination of LA in a complex sample. The chromatographic linear range is 2.5-30?gmL(-1) with LOD 1.774?gmL(-1). Chromatographic separation was achieved by isocratic elution (acetonitrile/potassium dihydrogen phosphate, pH 3, adjusted with phosphoric acid): 30/70 using a Cosmosil 5C(18)-MS-II (4.6mm×150mm I.D.) column at a flow rate of 1.0mLmin(-1). The presented methods were utilized to determine the ?-lipoic acid content in "Alfa-lipoic acid" capsules and in food products. PMID:22817954

Wo?yniec, E; Karpi?ska, J; Losiewska, S; Turkowicz, M; Klimczuk, J; Koj?o, A

2012-07-15

138

Radial lean direct injection burner  

DOEpatents

A burner for use in a gas turbine engine includes a burner tube having an inlet end and an outlet end; a plurality of air passages extending axially in the burner tube configured to convey air flows from the inlet end to the outlet end; a plurality of fuel passages extending axially along the burner tube and spaced around the plurality of air passage configured to convey fuel from the inlet end to the outlet end; and a radial air swirler provided at the outlet end configured to direct the air flows radially toward the outlet end and impart swirl to the air flows. The radial air swirler includes a plurality of vanes to direct and swirl the air flows and an end plate. The end plate includes a plurality of fuel injection holes to inject the fuel radially into the swirling air flows. A method of mixing air and fuel in a burner of a gas turbine is also provided. The burner includes a burner tube including an inlet end, an outlet end, a plurality of axial air passages, and a plurality of axial fuel passages. The method includes introducing an air flow into the air passages at the inlet end; introducing a fuel into fuel passages; swirling the air flow at the outlet end; and radially injecting the fuel into the swirling air flow.

Khan, Abdul Rafey; Kraemer, Gilbert Otto; Stevenson, Christian Xavier

2012-09-04

139

Purification of plasmid DNA using tangential flow filtration and tandem anion-exchange membrane chromatography.  

PubMed

A new bioprocess using mainly membrane operations to obtain purified plasmid DNA from Escherechia coli ferments was developed. The intermediate recovery and purification of the plasmid DNA in cell lysate was conducted using hollow-fiber tangential filtration and tandem anion-exchange membrane chromatography. The purity of the solutions of plasmid DNA obtained during each process stage was investigated. The results show that more than 97% of RNA in the lysate was removed during the process operations and that the plasmid DNA solution purity increased 28-fold. One of the main characteristics of the developed process is to avoid the use of large quantities of precipitating agents such as salts or alcohols. A better understanding of membrane-based technology for the purification of plasmid DNA from clarified E. coli lysate was developed in this research. The convenience of anion-exchange membranes, configured in ready-to-use devices can further simplify large-scale plasmid purification strategies. PMID:19083017

Guerrero-Germán, Patricia; Prazeres, Duarte M F; Guzmán, Roberto; Montesinos-Cisneros, Rosa Ma; Tejeda-Mansir, Armando

2009-08-01

140

Determination of the average volumetric flow rate in supercritical fluid chromatography.  

PubMed

This work reviews and discusses controversies and errors made in the determination of the average volumetric flow rate of a compressible mobile phase forced to flow through a chromatographic column. Proper estimates of the volumetric flow rate, which obviously changes along the column, are keys to understanding the retention mechanism that takes place inside the column and to achieve repeatable and reproducible separations. Each step of the calculation process will be discussed in detail, including how to estimate the variations of the pressure and the temperature along the column. The determination of the average volumetric flow rate requires the knowledge of the average density of the mobile phase and of its mass flow rate. The calculations were carried out under various experimental conditions, including different column temperatures and inlet pressures. The estimated values of the volumetric flow rate are validated by the conversion of the retention times to the retention volumes of nitrous oxide peaks, which is valid since this compound is assumed to be non retained, which makes it a hold-up time marker. PMID:24671042

Vajda, Péter; Stankovich, Joseph J; Guiochon, Georges

2014-04-25

141

The effects of the secondary fluid temperature on the energy transfer in an unsteady ejector with a radial-flow diffuser  

NASA Astrophysics Data System (ADS)

Unsteady ejectors are devices whereby energy is exchanged between directly interacting fluids. Unlike steady ejectors, the mechanism responsible for the energy transfer is reversible in nature and thus higher efficiencies are perceivable. A potential application for PEE is for enhancement in output power per weight as in turbochargers. The unsteady ejector when used as a turbocharger the device is expected to perform under wide range of ambient temperatures. Therefore, it is important to investigate the effects of the temperature of the induced ambient air on the energy transfer. The radial-flow ejector, which usually leads to higher-pressure ratios with fewer stages, was selected for the investigation. The flow field is investigated at two Mach numbers 2.5 and 3.0 utilizing rectangular short-length supersonic nozzles for accelerating the primary fluid. Fundamental to the enhancement of these devices performance relies on the management of the flow field in such a way to minimize entropy production. The numerical analyses were conducted utilizing a package of computational fluid dynamics.

Ababneh, Amer Khalil; Jawarneh, Ali M.; Tlilan, Hitham M.; Ababneh, Mohammad K.

2009-11-01

142

ANALYTICAL APPROXIMATION OF THE BIODEGRADATION RATE FOR IN SITU BIOREMEDIATION OF GROUNDWATER UNDER IDEAL RADIAL FLOW CONDITIONS. (R824785)  

EPA Science Inventory

We derive the long-term biodegradation rate of an organic contaminant (substrate) for an in situ bioremediation model with axisymmetric flow conditions. The model presumes that a nonsorbing electron acceptor is injected into a saturated homogeneous porous medium which initially c...

143

Capillary liquid chromatography fraction collection and postcolumn reaction using segmented flow microfluidics.  

PubMed

A challenge for capillary LC (cLC) is fraction collection and the manipulation of fractions from microscale columns. An emerging approach is the use of segmented flow or droplet technology to perform such tasks. In this work, a fraction collection and postcolumn reaction system based on segmented flow was developed for the gradient cLC of proteins. In the system, column effluent and immiscible oil are pumped into separate arms of a tee resulting in regular fractions of effluent segmented by oil. Fractions were generated at 1 Hz corresponding to 5 nL volumes. The fraction collection rate was high enough to generate over 30 fractions per peak and preserve chromatographic resolution achieved for a five-protein test mixture. The resulting fractions could be stored and subsequently derivatized for fluorescence detection by pumping them into a second tee where naphthalene dicarboxyaldehyde, a fluorogenic reagent, was pumped into a second arm and added to each fraction. Proteins were derivatized within the droplets enabling postcolumn fluorescence detection of the proteins. The experiments demonstrate that fraction collection from cLC by segmented flow can be extended to proteins. Further, they illustrate a potential workflow for protein analysis based on postcolumn derivatization for fluorescence detection. PMID:24039151

Nie, Jing; Kennedy, Robert T

2013-11-01

144

Hydrodynamic Chromatography  

NASA Astrophysics Data System (ADS)

Hydrodynamic chromatography (HDC) has experienced a resurgence in recent years for particle and polymer characterization, principally because of its coupling to a multiplicity of physical detection methods. When coupled to light scattering (both multiangle static and quasi-elastic), viscometric, and refractometric detectors, HDC can determine the molar mass, size, shape, and structure of colloidal analytes continuously and as a function of one another, all in a single analysis. In so doing, it exposes the analytes to less shear force (and, hence, less potential for flow-induced degradation) than in, for instance, size-exclusion chromatography. In this review, we discuss the fundamental chromatographic underpinnings of this technique in terms of retention, band broadening, and resolution, and we describe the power of multidetector HDC with examples from the recent literature.

Striegel, André M.; Brewer, Amandaa K.

2012-07-01

145

Radial Erosion  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

The ejecta surrounding the crater (off image to the left) in this image has undergone significant erosion by the wind. The wind has stripped the surface features from the ejecta and has started to winnow away the ejecta blanket. Near the margin of the ejecta the wind is eroding along a radial pattern -- taking advantage of radial emplacement. Note the steep margin of the ejecta blanket. Most, if not all, of the fine ejecta material has been removed and the wind in now working on the more massive continuous ejecta blanket.

Image information: VIS instrument. Latitude 12.5, Longitude 197.4 East (162.6 West). 37 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2005-01-01

146

Revised FORTRAN program for calculating velocities and streamlines on the hub-shroud midchannel stream surface of an axial-, radial-, or mixed-flow turbomachine or annular duct. 2: Programmer's manual  

NASA Technical Reports Server (NTRS)

A FORTRAN IV computer program has been developed that obtains a detailed subsonic or shock free transonic flow solution on the hub-shroud midchannel stream surface of a turbomachine. The blade row may be fixed or rotating, and the blades may be twisted and leaned. Flow may be axial, mixed, or radial. Upstream and downstream flow variables may vary from hub to shroud, and provisions are made to correct for loss of stagnation pressure. The results include velocities, streamlines, and flow angles on the stream surface and approximate blade surface velocities.

Katsanis, T.; Mcnally, W. D.

1977-01-01

147

Effects of chain decays, radial flow and $U_{A}(1)$ restoration on the low-mass dilepton enhancement in $\\sqrt{s_{NN}}=200$ GeV Au+Au reactions  

E-print Network

In sqrt(sNN) = 200 GeV Au+Au collisions PHENIX reported a significant enhancement in the low-mass region (0.1 low-mass dilepton enhancement using a radial flow dominated meson spectra, chain decays of long-lived resonances and an in-medium eta' mass modification.

Marton Vargyas; Robert Vertesi; Tamas Csorgo

2013-05-22

148

Measurement of fundamental chromatography parameters in conventional and split-flow comprehensive two-dimensional gas chromatography-mass spectrometry: A focus on the importance of second-dimension injection efficiency.  

PubMed

The present manuscript reports a comparative study between conventional and split-flow comprehensive GC×GC-MS. Conventional GC×GC-MS was performed by using a single GC oven, and with a widely employed apolar (30 m × 0.25 mm id)-polar (1 m × 0.10 mm id) column combination. Split-flow GC×GC-MS experiments were carried out by using the same first and second analytical columns, and by diverting part of the primary-capillary flow to waste, via a waste line. The latter was located at the conjunction point between the two dimensions. The measurement of fundamental gas chromatography parameters (efficiency, resolution), in both dimensions and under different experimental conditions, enabled the attainment of detailed information related to GC×GC-MS method optimization. Finally, the results derived from the present investigation highlight an important GC×GC issue, namely the efficiency of band reinjection onto the second-dimension capillary. PMID:23034883

Tranchida, Peter Quinto; Zoccali, Mariosimone; Franchina, Flavio Antonio; Dugo, Paola; Mondello, Luigi

2013-01-01

149

Turbulent flow chromatography TFC-tandem mass spectrometry supporting in vitro/vivo studies of NCEs in high throughput fashion.  

PubMed

Turbulent Flow Chromatography (TFC) is a powerful approach for on-line extraction in bioanalytical studies. It improves sensitivity and reduces sample preparation time, two factors that are of primary importance in drug discovery. In this paper the application of the ARIA system to the analytical support of in vivo pharmacokinetics (PK) and in vitro drug metabolism studies is described, with an emphasis in high throughput optimization. For PK studies, a comparison between acetonitrile plasma protein precipitation (APPP) and TFC was carried out. Our optimized TFC methodology gave better S/N ratios and lower limit of quantification (LOQ) than conventional procedures. A robust and high throughput analytical method to support hepatocyte metabolic stability screening of new chemical entities was developed by hyphenation of TFC with mass spectrometry. An in-loop dilution injection procedure was implemented to overcome one of the main issues when using TFC, that is the early elution of hydrophilic compounds that renders low recoveries. A comparison between off-line solid phase extraction (SPE) and TFC was also carried out, and recovery, sensitivity (LOQ), matrix effect and robustness were evaluated. The use of two parallel columns in the configuration of the system provided a further increase of the throughput. PMID:19896318

Verdirame, Maria; Veneziano, Maria; Alfieri, Anna; Di Marco, Annalise; Monteagudo, Edith; Bonelli, Fabio

2010-03-11

150

A fully automated turbulent-flow liquid chromatography-tandem mass spectrometry technique for monitoring antidepressants in human serum.  

PubMed

Antidepressants belong to a variety of chemical and pharmacologic classes. Most require therapeutic drug monitoring, at least in certain circumstances, such as unexplained inefficacy or suspected toxicity. Several types of chromatographic methods have generally been used. This paper presents a fully automated, sensitive, and specific method for the therapeutic drug monitoring of 13 antidepressants of all classes (amoxapine, amitriptyline, citalopram, clomipramine, dothiepin, doxepin, fluoxetine, imipramine, maprotiline, mianserin, paroxetine, sertraline, trimipramine) and some of their respective active metabolites (nortriptyline, monodesmethylcitalopram, desmethylclomipramine, desipramine, norfluoxetine, desmethylmianserin, N-desmethylsertraline), based on the innovative turbulent-flow liquid chromatography (TFC) technology, coupled to tandem-mass spectrometry (MS/MS). The antidepressants were divided in two groups depending on their chromatographic properties, so that two injections would be necessary to screen all compounds (which is infrequent for therapeutic drug monitoring). Calibration curves ranged from 10 to 500 ng/mL. No significant memory effect was observed after the injection of a blank serum sample spiked at 500 ng/mL. The intra-assay and inter-assay precision CVs ranged from 0.4% to 12% and from 1% to 16%, respectively. The method was further validated by blindly analyzing Heathcontrol-Therapeutic Drugs Scheme samples (Cardiff Bioanalytical Services Ltd.) containing several antidepressants. PMID:16418706

Sauvage, F L; Gaulier, J M; Lachâtre, G; Marquet, P

2006-02-01

151

High-pressure size exclusion chromatography analysis of dissolved organic matter isolated by tangential-flow ultra filtration  

USGS Publications Warehouse

A 1,000-Dalton tangential-flow ultrafiltration (TFUF) membrane was used to isolate dissolved organic matter (DOM) from several freshwater environments. The TFUF unit used in this study was able to completely retain a polystyrene sulfonate 1,800-Dalton standard. Unaltered and TFUF-fractionated DOM molecular weights were assayed by high-pressure size exclusion chromatography (HPSEC). The weight-averaged molecular weights of the retentates were larger than those of the raw water samples, whereas the filtrates were all significantly smaller and approximately the same size or smaller than the manufacturer-specified pore size of the membrane. Moreover, at 280 nm the molar absorptivity of the DOM retained by the ultrafilter is significantly larger than the material in the filtrate. This observation suggests that most of the chromophoric components are associated with the higher molecular weight fraction of the DOM pool. Multivalent metals in the aqueous matrix also affected the molecular weights of the DOM molecules. Typically, proton-exchanged DOM retentates were smaller than untreated samples. This TFUF system appears to be an effective means of isolating aquatic DOM by size, but the ultimate size of the retentates may be affected by the presence of metals and by configurational properties unique to the DOM phase.

Everett, C.R.; Chin, Y.-P.; Aiken, G.R.

1999-01-01

152

Development and validation of a radial inflow turbine model for simulation of the SNL S-CO2 split-flow loop.  

SciTech Connect

A one-dimensional model for a radial inflow turbine has been developed for super-critical carbon dioxide (S-CO{sub 2}) Brayton cycle applications. The model accounts for the main phenomena present in the volute, nozzle, and impeller of a single-stage turbine. These phenomena include internal losses due to friction, blade loading, and angle of incidence and parasitic losses due to windage and blade-housing leakage. The model has been added as a component to the G-PASS plant systems code. The model was developed to support the analysis of S-CO{sub 2} cycles in conjunction with small-scale loop experiments. Such loops operate at less than a MWt thermal input. Their size permits components to be reconfigured in new arrangements relatively easily and economically. However, the small thermal input combined with the properties of carbon dioxide lead to turbomachines with impeller diameters of only one to two inches. At these sizes the dominant phenomena differ from those in larger more typical machines. There is almost no treatment in the literature of turbomachines at these sizes. The present work therefore is aimed at developing turbomachine models that support the task of S-CO{sub 2} cycle analysis using small-scale tests. Model predictions were compared against data from an experiment performed for Sandia National Laboratories in the split-flow Brayton cycle loop currently located at Barber-Nichols Inc. The split-flow loop incorporates two turbo-alternator-compressor (TAC) units each incorporating a radial inflow turbine and a radial flow compressor on a common shaft. The predicted thermodynamic conditions at the outlet of the turbine on the main compressor shaft were compared with measured values at different shaft speeds. Two modifications to the original model were needed to better match the experiment data. First, a representation of the heat loss from the volute downstream of the sensed inlet temperature was added. Second, an empirical multiplicative factor was applied to the Euler head and another to the head loss to bring the predicted outlet pressure into better agreement with the experiment. These changes also brought the overall efficiency of the turbine into agreement with values cited by Barber Nichols for small turbines. More generally, the quality of measurement set data can in the future be improved by additional steps taken in the design and operation of the experimental apparatus. First, a thermocouple mounted at the nozzle inlet would provide a better indication of temperature at this key point. Second, heat losses from the turbine should be measured directly. Allowing the impeller to free wheel at inlet conditions and measuring the temperature drop between inlet and outlet would provide a more accurate measure of heat loss. Finally, the enthalpy change during operation is more accurately obtained by measuring the torque on the stator using strain gauges rather than by measuring pressure and temperature at inlet and outlet to infer thermodynamic states.

Vilim, R. B. (Nuclear Engineering Division)

2012-07-31

153

Efficient Separations of Intact Proteins Using Slip-Flow with Nano-Liquid Chromatography–Mass Spectrometry  

PubMed Central

A capillary with a pulled tip, densely packed with silica particles of 0.47 ?m in diameter, is shown to provide higher peak capacity and sensitivity in the separation of intact proteins by reversed-phase liquid chromatography–mass spectrometry (LC–MS). For a C18 bonded phase, slip flow gave a 10-fold flow enhancement to allow for stable nanospray with a 4-cm column length. Model proteins were studied: ribonuclease A, trypsin inhibitor, and carbonic anhydrase, where the latter had impurities of superoxide dismutase and ubiquitin. The proteins were well separated at room temperature with negligible peak tailing. The peak capacity for ubiquitin was 195 for a 10-min gradient and 315 for a 40-min gradient based on Gaussian fitting of the entire peak, rather than extrapolating the full-width at half-maximum. Separation of a cell lysate with a 60 min gradient showed extremely high peak capacities of 750 and above for a peptide and relatively homogeneous proteins. Clean, low noise mass spectra for each model protein were obtained. The physical widths of the peaks were an order of magnitude narrower than those of conventional columns, giving increased sensitivity. All proteins except ubiquitin exhibited significant heterogeneity apparently due to multiple proteoforms, as indicated by both peak shapes and mass spectra. The chromatograms exhibited excellent reproducibility in retention time, with relative standard deviations of 0.09 to 0.34%. The results indicate that submicrometer particles are promising for improving the separation dimension of LC in top-down proteomics. PMID:24383398

2015-01-01

154

Radial Inflow Turboexpander Redesign  

SciTech Connect

Steamboat Envirosystems, LLC (SELC) was awarded a grant in accordance with the DOE Enhanced Geothermal Systems Project Development. Atlas-Copco Rotoflow (ACR), a radial expansion turbine manufacturer, was responsible for the manufacturing of the turbine and the creation of the new computer program. SB Geo, Inc. (SBG), the facility operator, monitored and assisted ACR's activities as well as provided installation and startup assistance. The primary scope of the project is the redesign of an axial flow turbine to a radial inflow turboexpander to provide increased efficiency and reliability at an existing facility. In addition to the increased efficiency and reliability, the redesign includes an improved reduction gear design, and improved shaft seal design, and upgraded control system and a greater flexibility of application

William G. Price

2001-09-24

155

Spectra and radial flow in relativistic heavy ion collisions with Tsallis statistics in a blast-wave description  

NASA Astrophysics Data System (ADS)

We have implemented the Tsallis statistics in a Blast-Wave model (TBW) and applied it to midrapidity transverse-momentum spectra of identified particles measured at BNL Relativistic Heavy Ion Collider (RHIC). This new TBW function fits the RHIC data very well for pT<3 GeV/c. We observed that the collective flow velocity starts from zero in p+p and peripheral Au+Au collisions and grows to 0.470±0.009c in central Au+Au collisions. The resulting (q-1) parameter, which characterizes the degree of nonequilibrium in a system, indicates an evolution from a highly nonequilibrated system in p+p collisions toward an almost thermalized system in central Au+Au collisions. The temperature and collective velocity are well described by a quadratic dependence on (q-1). Two sets of parameters in our TBW are required to describe the meson and baryon groups separately in p+p collisions while one set appears to fit all spectra in central Au+Au collisions.

Tang, Zebo; Xu, Yichun; Ruan, Lijuan; van Buren, Gene; Wang, Fuqiang; Xu, Zhangbu

2009-05-01

156

Simultaneous determination of some food additives in soft drinks and other liquid foods by flow injection on-line dialysis coupled to high performance liquid chromatography  

Microsoft Academic Search

Flow injection on-line dialysis was developed for sample pretreatment prior to the simultaneous determination of some food additives by high performance liquid chromatography (FID–HPLC). A liquid sample or mixed standard solution (900?L) was injected into a donor stream (5%, w\\/v, sucrose) of FID system and was pushed further through a dialysis cell, while an acceptor solution (0.025molL?1 phosphate buffer, pH

Orawan Kritsunankul; Jaroon Jakmunee

2011-01-01

157

Hydrodynamic flow in capillary-channel fiber columns for liquid chromatography.  

PubMed

The flow characteristics of capillary-channel polymer (C-CP) fiber liquid chromatographic (LC) columns have been investigated. The C-CP fibers are manufactured with eight longitudinal grooves (capillary channels) extending the length of the fibers. Three C-CP fiber examples were studied, with fiber dimensions ranging from approximately 35 microm to 65 microm, and capillary-channel dimensions ranging from approximately 6 microm to 35 microm. The influence of fiber packing density and column inner diameter on peak asymmetry, peak width, and run-to-run reproducibility have been studied for stainless steel LC columns packed with polyester (PET) and polypropylene (PP) C-CP fibers. The van Deemter A-term was evaluated as a function of fiber packing density (approximately 0.3 g/cm(3)-0.75 g/cm(3)) for columns of 4.6 mm inner diameter (i.d.) and at constant packing densities for 1.5 mm, 3.2 mm, 4.6 mm, and 7.7 mm i.d. columns. Although column diameter had little influence on the eluting peak widths, peak asymmetry increased with increasing column diameter. The A-terms for the C-CP fiber packed columns are somewhat larger than current commercial, microparticulate-packed columns, and means for improvement are discussed. Applications in the area of protein (macromolecule) separations appear the most promising at this stage of the system development. PMID:16194542

Stanelle, Rayman D; Sander, Lane C; Marcus, R Kenneth

2005-12-23

158

Profiling of oxidized phospholipids in lipoproteins from patients with coronary artery disease by hollow fiber flow field-flow fractionation and nanoflow liquid chromatography-tandem mass spectrometry.  

PubMed

Oxidized phospholipids (Ox-PLs) are oxidatively modified PLs that are produced during the oxidation of lipoproteins; oxidation of low density lipoproteins especially is known to be associated with the development of coronary artery disease (CAD). In this study, different lipoprotein classes (high density, low density, and very low density lipoproteins) from pooled plasma of CAD patients and pooled plasma from healthy controls were size-sorted on a semipreparative scale by multiplexed hollow fiber flow field-flow fractionation (MxHF5), and Ox-PLs that were extracted from each lipoprotein fraction were quantified by nanoflow liquid chromatography-tandem mass spectrometry (nLC-ESI-MS/MS). The present study showed that oxidation of lipoproteins occurred throughout all classes of lipoproteins with more Ox-PLs identified from CAD patient lipoproteins: molecular structures of 283 unique PL species (including 123 Ox-PLs) from controls and 315 (including 169 Ox-PLs) from patients were identified by data-dependent collision-induced dissociation experiments. It was shown that oxidation of PLs occurred primarily with hydroxylation of PL; in particular, a saturated acyl chain such as 16:0, 18:0, or even 18:1 at the sn-1 location of the glycerol backbone along with sn-2 acyl chains with at least two double bonds were identified. The acyl chain combinations commonly found for hydroxylated Ox-PLs in the lipoproteins of CAD patients were 16:0/18:2, 16:0/20:4, 18:0/18:2, and 18:0/20:4. PMID:25494038

Lee, Ju Yong; Byeon, Seul Kee; Moon, Myeong Hee

2015-01-20

159

Simulations of the Neutral-beam-induced Rotation, Radial Electric Field, and Flow Shearing Rate in Next-step Burning Plasmas  

SciTech Connect

Toroidal rotation of plasmas in present tokamaks is beneficial for increasing the stability to wall-induced MHD and appears to reduce the anomalous transport associated with micro-turbulence. This paper calculates the toroidal rotation expected from neutral-beam injection in the proposed FIRE and ITER-FEAT tokamak reactors. Self-consistent burning plasmas for these tokamaks have been constructed using the TRANSP plasma analysis code. Neutral-beam injection has been proposed for FIRE and ITER-FEAT. The neutral-beam-induced torques are computed, and assumptions for the anomalous transport of toroidal angular momentum are used to calculate the toroidal rotation profiles. The central Mach numbers are about 3-8%. The ratio of the rotation speed to the Alfvin speed is less than 1%. Assuming neoclassical poloidal rotation and force balance, the radial electric field and flow shearing rate are calculated. Peak shearing rates near the outboard edge are in the 10-100 krad/s range.

R.V. Budny

2002-08-13

160

Application of a radial-flow bioreactor in the production of beta1,3-N-acetylglucosaminyltransferase-2 fused with GFPuv using stably transformed insect cell lines.  

PubMed

An RFB (radial-flow bioreactor) with a reactor volume of 5 ml was applied to produce human beta3GnT (beta1,3-N-acetylglucosaminyltransferase) using two stably transformed insect cell lines. When air was supplied to the RFB, cell growth stopped at 4 days of culture and beta3GnT was not detected. However, with a supply of pure oxygen, the cell concentration, assumed from glucose consumption, increased by 1.3x10(7) cells/ml. Insect cells attached to poly(vinyl alcohol) matrixes packed in the RFB and grew confluently; 5.6 m-units/ml beta3GnT was produced under the conditions of pure oxygen supply and addition of glucose and glutamine. This RFB was first applied in beta3GnT production using stably transformed insect cells. The amount of beta3GnT production in only a 5 ml-scale RFB was comparable with that of a 100 ml shaking flask culture. PMID:15636581

Kwon, Mi Sun; Kato, Tatsuya; Dojima, Takashi; Park, Enoch Y

2005-08-01

161

CALIBRATION OF SUBMERGED RADIAL GATES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Calibration equations for free-flowing radial gates typically provide sufficient accuracy for irrigation district operations. However, many districts have difficulty in determining accurate discharges when the downstream water level begins to submerge the gate. Based on laboratory studies, we have d...

162

Applying Chromatography.  

ERIC Educational Resources Information Center

Presents three experiments to introduce students to different kinds of chromatography: (1) paper chromatography; (2) gel filtration chromatography; and (3) reverse-phase liquid chromatography. Written in the form of a laboratory manual, explanations of each of the techniques, materials needed, procedures, and a glossary are included. (PVD)

Klein, Jessie W.; Patev, Paul

1998-01-01

163

Revised FORTRAN program for calculating velocities and streamlines on the hub-shroud midchannel stream surface of an axial-, radial-, or mixed-flow turbomachine or annular duct. 1: User's manual  

NASA Technical Reports Server (NTRS)

A FORTRAN 4 computer program was developed that obtains a detailed subsonic or shock-free transonic flow solution on the hub-shroud midchannel stream surface of a turbomachine. The blade row may be fixed or rotating, and the blades may be twisted and leaned. Flow may be axial, mixed, or radial. Upstream and downstream flow variables may vary from hub to shroud, and provision is made to correct for loss of stagnation pressure. The results include velocities, streamlines, and flow angles on the stream surface as well as approximate blade surface velocities. Subsonic solutions are obtained by a finite-difference, stream-function solution. Transonic solutions are obtained by a velocity-gradient method that uses information from a finite-difference, stream-function solution at a reduced mass flow.

Katsanis, T.; Mcnally, W. D.

1977-01-01

164

Differentiating organically and conventionally grown oregano using ultraperformance liquid chromatography mass spectrometry (UPLC-MS), headspace gas chromatography with flame ionization detection (headspace-GC-FID), and flow injection mass spectrum (FIMS) fingerprints combined with multivariate data analysis.  

PubMed

Ultraperformance liquid chromatography mass spectrometry (UPLC-MS), flow injection mass spectrometry (FIMS), and headspace gas chromatography (headspace-GC) combined with multivariate data analysis techniques were examined and compared in differentiating organically grown oregano from that grown conventionally. It is the first time that headspace-GC fingerprinting technology is reported in differentiating organically and conventionally grown spice samples. The results also indicated that UPLC-MS, FIMS, and headspace-GC-FID fingerprints with OPLS-DA were able to effectively distinguish oreganos under different growing conditions, whereas with PCA, only FIMS fingerprint could differentiate the organically and conventionally grown oregano samples. UPLC fingerprinting provided detailed information about the chemical composition of oregano with a longer analysis time, whereas FIMS finished a sample analysis within 1 min. On the other hand, headspace GC-FID fingerprinting required no sample pretreatment, suggesting its potential as a high-throughput method in distinguishing organically and conventionally grown oregano samples. In addition, chemical components in oregano were identified by their molecular weight using QTOF-MS and headspace-GC-MS. PMID:25050447

Gao, Boyan; Qin, Fang; Ding, Tingting; Chen, Yineng; Lu, Weiying; Yu, Liangli Lucy

2014-08-13

165

On-line stop-flow two-dimensional liquid chromatography-mass spectrometry method for the separation and identification of triterpenoid saponins from ginseng extract.  

PubMed

A method based on stop-flow two-dimensional liquid chromatography coupled with electrospray ionization mass spectrometry (2D LC-ESI MS) was established and applied to analyze triterpenoid saponins from the main root of ginseng. Due to the special structure of triterpenoid saponins (they contain polar sugar side chains and nonpolar aglycones), hydrophilic interaction chromatography (HILIC) and reversed-phase liquid chromatography (RPLC) were used for the two dimensions, respectively. A trap column was used to connect the two dimensions. The dilution effect, which is one of the main shortcomings of traditional comprehensive 2D LC methods, was largely avoided. The peak capacity of this system was 747 and the orthogonality was 56.6 %. Compared with one-dimensional HILIC or RP LC MS analysis, 257 and 185 % more mass spectral peaks (ions with intensities that were higher than 1,000) were obtained from the ginseng main root extracts, and 94 triterpenoid saponins were identified based on MS(n) information and summarized aglycone structures. Given its good linearity and repeatability, the established method was successfully applied to classify ginsengs of different ages (i.e., years of growth), and 19 triterpenoid saponins were found through statistical analysis to vary in concentration depending on the age of the ginseng. PMID:25410638

Wang, Shuangyuan; Qiao, Lizhen; Shi, Xianzhe; Hu, Chunxiu; Kong, Hongwei; Xu, Guowang

2015-01-01

166

On radial geodesic forcing of zonal modes  

SciTech Connect

The elementary local and global influence of geodesic field line curvature on radial dispersion of zonal modes in magnetised plasmas is analysed with a primitive drift wave turbulence model. A net radial geodesic forcing of zonal flows and geodesic acoustic modes can not be expected in any closed toroidal magnetic confinement configuration, since the flux surface average of geodesic curvature identically vanishes. Radial motion of poloidally elongated zonal jets may occur in the presence of geodesic acoustic mode activity. Phenomenologically a radial propagation of zonal modes shows some characteristics of a classical analogon to second sound in quantum condensates.

Kendl, A. [Institute for Ion Physics and Applied Physics, Association Euratom-OeAW, University of Innsbruck, A-6020 Innsbruck (Austria)

2011-07-15

167

Model for nonequilibrium binding and affinity chromatography: characterization of 8-hydroxyquinoline immobilized on controlled pore glass using a flow injection system with a packed microcolumn  

PubMed

This paper discusses the use of pulse techniques for analysis of zonal elution data for the determination of mass-transfer and axial dispersion constants for porous support materials with adsorption to the surface or to a surface-bonded phase. As an example, this paper considers the case of controlled pore glass (CPG) with a bonded phase that is used with microcolumns and a flow injection analysis system. For the CPG, axial dispersion in the form of eddy mixing can be described by l = 0.203, and the overall mass-transfer term, K(OL) = 3.9 x 10(-6) cm/s. Additionally, an affinity chromatography model was adapted to effectively describe systems employing CPG as the support material through modification of equations describing typical affinity chromatography systems and by inclusion of an axial dispersion term in the calculation of N. This model was used to predict breakthrough curves for cadmium adsorption by 8-hydroxyquinolinol immobilized on CPG packed in microcolumns. In general, the information from the model can be used to extract equilibrium-based constants (binding strengths and site capacities) from a nonequilibrium flow system. The data and model can also be employed in determining the performance for scaled-up extraction systems. The modified model is available in EXCEL spreadsheet format as Supporting Information. PMID:10959984

Howard; Holcombe

2000-08-15

168

Improving Peak Capacity in Fast On-Line Comprehensive Two-Dimensional Liquid Chromatography with Post First Dimension Flow-Splitting  

PubMed Central

The use of flow splitters between the two dimensions in on-line comprehensive two dimensional liquid chromatography (LC×LC) has not received very much attention in comparison to their use in GC×GC where they are quite common. In principle, splitting the flow after the first dimension column and performing on-line LC×LC on this constant fraction of the first dimension effluent should allow the two dimensions to be optimized almost independently. When there is no flow splitting any change in the first dimension flow rate has an immediate impact on the second dimension. With a flow splitter one could for example double the flow rate into the first dimension column and do a 1:1 flow split without changing the sample loop size or the sampler’s collection time. Of course, the sensitivity would be diminished but this can be partially compensated by use of a larger injection; this will likely only amount to a small price to pay for this increased resolving power and system flexibility. Among other benefits, we found a 2-fold increase in the corrected 2D peak capacity and the number of observed peaks for a 15 min analysis time by using a post first dimension flow splitter. At a fixed analysis time this improvement results primarily from an increase in the gradient time resulting from the reduced system re-equilibration time and to a smaller extent it is due to the increased peak capacity achieved by full optimization of the first dimension. PMID:22017622

Filgueira, Marcelo R.; Huang, Yuan; Witt, Klaus; Castells, Cecilia; Carr, Peter W.

2011-01-01

169

Chromatography Theory  

NSDL National Science Digital Library

James Hardy has produced a number of presentation-style lecture modules for analytical chemistry. This is a very good module that covers the introductory theory of chromatography. The material includes information on chromatography along with plate and kinetic theories. It is a colorful and well planned presentation of the introduction to chromatography that could be used as the basis for lectures on chromatography at the introductory analytical chemistry or instrumental analysis level.

170

Affinity Chromatography  

NSDL National Science Digital Library

This is an experiment showing the application of affinity chromatography to the separation of albumin from horse serum. A brief introduction of affinity chromatography and how it is being used in this specific experiment is given. This appears to be a good experiment to show the advantages of affinity chromatography in separating specific proteins from a complex matrix and would be useful in a biochemistry course or a course that is specifically looking at differing types of chromatography.

DiResta, Dan

171

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

Microsoft Academic Search

The objective of this work was to develop a reliable, ragged high?performance liquid chromatographic (HPLC) method for determination of trace levels of bromate (< 10 ?g\\/l) in bottled water. HPLC separation was achieved by ion interaction chromatography using a C?18 reversed?phase column and a mobile phase consisting of methanol\\/water (20:80, v\\/v) with tetrabutylammonium acetate as the ion interaction reagent. A

Charles R. Warner; Daniel H. Daniels; Frank L. Joe Jr; Gregory W. Diachenko

1996-01-01

172

Pressure jumps due to flow interruptions as source of system peaks in liquid chromatography with mixed eluents  

Microsoft Academic Search

Summary  Brief pressure changes take often place within a liquid chromatography column, e.g., during sample injection. It is shown\\u000a that pressure jumps may cause local changes in the composition of a mixed effluent and the rise of system peaks in the chromatogram.\\u000a This is a consequence of the dependence of sorption equilibrium on pressure.

T. Macko; L. Šoltés; D. Berek

1989-01-01

173

A meshless method on non-Fickian flows with mixing length growth in porous media based on radial basis functions: A comparative study  

Microsoft Academic Search

The present study aims to introduce a solution for parabolic integro-differential equations arising in heat conduction in materials with memory, which naturally occur in many applications. Two Radial basis functions (RBFs) collocation schemes are employed for solving this equation. The first method tested is an unsymmetric method, and the second one, which appears to be more efficient, is a symmetric

S. Kazem; J. A. Rad; K. Parand

174

3D velocity from 3D Doppler radial velocity  

Microsoft Academic Search

We present local least squares and regularization frameworks for computing 3D velocity (3D optical flow) from 3D radial velocity measured by a Doppler radar. We demonstrate the perfor- mance of our algorithms quantitatively on synthetic radial velocity data and qualitatively on real radial velocity data, obtained from the Doppler radar at Kurnell Radar station, Botany Bay, New South Wales, Australia.

J. L. Barron; R. E. Mercer; X. Chen; P. Joe

2005-01-01

175

Impact of radial artery cannulation for coronary angiography and angioplasty on radial artery function.  

PubMed

The radial artery is commonly used as a conduit in coronary artery bypass grafting. No data exist on the effects of radial sheath insertion on radial artery function. Because many patients considered for coronary artery bypass grafting have had previous radial procedures, it is important to understand any effects radial sheath insertion may have on radial artery function. Twenty-two patients who underwent elective coronary angiography or angioplasty with a 6Fr sheath through the right radial artery were studied. Radial artery function was assessed using ultrasound to measure flow-mediated dilation (FMD). Reactive hyperemia was produced by 5-minute cuff inflation on the arm to suprasystolic pressures. Radial artery diameter was measured at rest and 1 minute after cuff deflation. FMD was expressed as percent change in radial diameter compared with at rest. In all cases, the left radial artery was studied as a control. Patients were studied before sheath insertion, immediately after sheath insertion, and 6 weeks after sheath insertion. The FMD of the cannulated arm was 13.2% before sheath insertion versus 3.6% immediately after sheath insertion (p <0.01) and 0.2% (p <0.01) 9 weeks after sheath insertion. In contrast, there were no significant changes in the noncannulated arm at either time point. In conclusion, radial artery sheath insertion for coronary angiography or angioplasty results in immediate and persistent blunting of FMD, suggesting severe vasomotor dysfunction. Radial artery sheath insertion has important effects on radial artery function that must be considered when selecting radial conduits for coronary artery bypass grafting. PMID:17293183

Burstein, Jason M; Gidrewicz, Dominica; Hutchison, Stuart J; Holmes, Kate; Jolly, Sanjit; Cantor, Warren J

2007-02-15

176

Screening for multiple phosphodiesterase type 5 inhibitor drugs in dietary supplement materials by flow injection mass spectrometry and their quantification by liquid chromatography tandem mass spectrometry.  

PubMed

A flow injection tandem mass spectrometry method (FI-MS/MS) has been developed to detect enzyme phosphodiesterase type 5 inhibitors, including tadalafil, sildenafil, and vardenafil. Multiple reaction monitoring (MRM) was used to detect the drugs and product ion ratios were used for identification. FI-MS/MS was used for semi-quantification and liquid chromatography tandem mass spectrometry (LC-MS/MS) was used for further confirmation and quantification. One of 13 samples has been found to be adulterated with prescription levels of tadalafil and also low level of sildenafil. The method can be used for screening large numbers of herbal products for adulteration since it takes less than 1 min without chromatographic separation on a column. PMID:22695818

Song, Fenhong; El-Demerdash, Aref; Lee, Shwn-Ji Susie H

2012-11-01

177

Affinity Chromatography GST-tagged Proteins  

E-print Network

Affinity Chromatography GST-tagged Proteins His-tagged Proteins Antibody Immobilization Nucleotide binding Proteins Phospho-Aminoacid binding Proteins www.jenabioscience.com #12;Table of Contents AffinityChromatography Affinity Chromatography 3 GST-tagged Proteins 4 Glutathione ChroMatrixTM, Fast Flow 4 GST Cleavage Capture

Lebendiker, Mario

178

LASERS AND AMPLIFIERS: Influence of the Mach number of the oxidant flow on the energy and gasdynamic characteristics of a supersonic cw chemical HF laser with a radial-expansion nozzle array  

NASA Astrophysics Data System (ADS)

An experimental investigation was made of the energy and gasdynamic characteristics of a supersonic cw chemical HF laser with three radial-expansion nozzle arrays (nozzle — sonic injector configuration) of 35 cm × 10 cm dimensions, but differing in respect of the geometric expansion ratio of the nozzles. The distributions of the Mach number, of the static pressure, and of the total pressure behind a plane shock wave were determined in the flow field of the active medium. An increase in the geometric expansion ratio of the nozzles, subject to a constant pressure at the oxidant exit, i.e. an increase in the Mach number of the oxidant flow did not increase significantly the total pressure in the flowing active medium because of large pressure losses during flow through the nozzles and in the course of mixing with hydrogen jets. An increase in the calculated Mach number of the oxidant flow from 4.2 to 5.4 reduced by 26% the specific output energy of the laser, tracking the concurrent increase of the static pressure in the lasing zone.

Rebone, Vitalii K.; Rotinyan, Mikhail A.; Fedorov, Igor'A.; Krivitskii, A. M.; Moroz, M. V.

1998-02-01

179

Influence of the Mach number of the oxidant flow on the energy and gasdynamic characteristics of a supersonic cw chemical HF laser with a radial-expansion nozzle array  

SciTech Connect

An experimental investigation was made of the energy and gasdynamic characteristics of a supersonic cw chemical HF laser with three radial-expansion nozzle arrays (nozzle - sonic injector configuration) of 35 cm x 10 cm dimensions, but differing in respect of the geometric expansion ratio of the nozzles. The distributions of the Mach number, of the static pressure, and of the total pressure behind a plane shock wave were determined in the flow field of the active medium. An increase in the geometric expansion ratio of the nozzles, subject to a constant pressure at the oxidant exit, i.e. an increase in the Mach number of the oxidant flow did not increase significantly the total pressure in the flowing active medium because of large pressure losses during flow through the nozzles and in the course of mixing with hydrogen jets. An increase in the calculated Mach number of the oxidant flow from 4.2 to 5.4 reduced by 26% the specific output energy of the laser, tracking the concurrent increase of the static pressure in the lasing zone. (lasers and amplifiers)

Rebone, Vitalii K; Rotinyan, Mikhail A; Fedorov, Igor' A; Krivitskii, A M; Moroz, M V [Russian Science Centre 'Applied Chemistry', St Petersburg (Russian Federation)

1998-02-28

180

Dielectrokinetic chromatography devices  

DOEpatents

Disclosed herein are methods and devices for dielectrokinetic chromatography. As disclosed, the devices comprise microchannels having at least one perturber which produces a non-uniformity in a field spanning the width of the microchannel. The interaction of the field non-uniformity with a perturber produces a secondary flow which competes with a primary flow. By decreasing the size of the perturber the secondary flow becomes significant for particles/analytes in the nanometer-size range. Depending on the nature of a particle/analyte present in the fluid and its interaction with the primary flow and the secondary flow, the analyte may be retained or redirected. The composition of the primary flow can be varied to affect the magnitude of primary and/or secondary flows on the particles/analytes and thereby separate and concentrate it from other particles/analytes.

Chirica, Gabriela S; Fiechtner, Gregory J; Singh, Anup K

2014-12-16

181

Radial arm strike rail  

DOEpatents

The radial arm strike rail assembly is a system for measurement of bearings, directions, and stereophotography for geologic mapping, particularly where magnetic compasses are not appropriate. The radial arm, pivoting around a shaft axis, provides a reference direction determination for geologic mapping and bearing or direction determination. The centerable and levelable pedestal provide a base for the radial arm strike rail and the telescoping camera pedestal. The telescoping feature of the radial arm strike rail allows positioning the end of the rail for strike direction or bearing measurement with a goniometer.

McKeown, Mark H. (Golden, CO); Beason, Steven C. (Lakewood, CO)

1991-01-01

182

Column Chromatography  

NSDL National Science Digital Library

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

Yu, Julie

2007-01-01

183

Chromatography Theory  

NSDL National Science Digital Library

This site contains standard definitions related to chromatography similar to treatments found in analytical chemistry textbooks. It introduces the beginning student to Liquid Chromatography concepts relevant to biochemistry and includes a good example of choosing a mobile phase pH for a protein separation based on ion exchange.

184

Plastic Models Designed to Produce Large Height-to-Length Ratio Steady-State Planar and Axisymmetric (Radial) Viscous Liquid Laminar Flow Gravity Currents  

ERIC Educational Resources Information Center

Naturally occurring gravity currents include events such as air flowing through an open front door, a volcanic eruption's pyroclastic flow down a mountainside, and the spread of the Bhopal disaster's methyl isocyanate gas. Gravity currents typically have a small height-to-distance ratio. Plastic models were designed and constructed with a…

Blanck, Harvey F.

2012-01-01

185

Automated on-line renewable solid-phase extraction-liquid chromatography exploiting multisyringe flow injection-bead injection lab-on-valve analysis.  

PubMed

In this paper, the third generation of flow injection analysis, also named the lab-on-valve (LOV) approach, is proposed for the first time as a front end to high-performance liquid chromatography (HPLC) for on-line solid-phase extraction (SPE) sample processing by exploiting the bead injection (BI) concept. The proposed microanalytical system based on discontinuous programmable flow features automated packing (and withdrawal after single use) of a small amount of sorbent (<5 mg) into the microconduits of the flow network and quantitative elution of sorbed species into a narrow band (150 microL of 95% MeOH). The hyphenation of multisyringe flow injection analysis (MSFIA) with BI-LOV prior to HPLC analysis is utilized for on-line postextraction treatment to ensure chemical compatibility between the eluate medium and the initial HPLC gradient conditions. This circumvents the band-broadening effect commonly observed in conventional on-line SPE-based sample processors due to the low eluting strength of the mobile phase. The potential of the novel MSFI-BI-LOV hyphenation for on-line handling of complex environmental and biological samples prior to reversed-phase chromatographic separations was assessed for the expeditious determination of five acidic pharmaceutical residues (viz., ketoprofen, naproxen, bezafibrate, diclofenac, and ibuprofen) and one metabolite (viz., salicylic acid) in surface water, urban wastewater, and urine. To this end, the copolymeric divinylbenzene-co-n-vinylpyrrolidone beads (Oasis HLB) were utilized as renewable sorptive entities in the micromachined unit. The automated analytical method features relative recovery percentages of >88%, limits of detection within the range 0.02-0.67 ng mL(-1), and coefficients of variation <11% for the column renewable mode and gives rise to a drastic reduction in operation costs ( approximately 25-fold) as compared to on-line column switching systems. PMID:16615800

Quintana, José Benito; Miró, Manuel; Estela, José Manuel; Cerdà, Víctor

2006-04-15

186

Direct analysis of eight chlorophenols in urine by large volume injection online turbulent flow solid-phase extraction liquid chromatography with multiple wavelength ultraviolet detection.  

PubMed

A novel method for determining eight chlorophenols (CPs) by large volume injection online turbulent flow solid-phase extraction high performance liquid chromatography in urine samples was developed. An aliquot of 1.0 mL urine sample could be analyzed directly after centrifugation. The analytes were preconcentrated online on a Turboflow C18-P SPE column, eluted in back-flush mode, and then separated on an Acclaim PA2 analytical column. Major parameters such as SPE column type, sample loading flow rate and elution time were optimized in detail. Eight CPs from monochlorophenol to pentacholophenol were measured by multiple-wavelength UV detection at four different wavelengths. The limits of detection (LODs) were between 0.5 and 2 ng/mL. The linearity range was from the limit of quantification to 1000 ng/mL for each compound, with the coefficients of determination (r(2)) ranging from 0.9990 to 0.9996. The reproducibility of intraday and interday relative standard deviations (RSDs) ranged from 0.6% to 4.5% (n=5). The method was successfully applied to analyze eight CPs in urine samples. Good recoveries, ranging from 76.3% to 122.9%, were obtained. This simple, sensitive and accurate method provides an alternative way to rapidly analyze and monitor CPs in urine samples, especially for matters of occupational exposure. PMID:24401430

Guo, Feng; Liu, Qian; Shi, Jian-bo; Wei, Fu-sheng; Jiang, Gui-bin

2014-02-01

187

Chromatography 50 Chem 355 Jasperse Chromatography  

E-print Network

Chromatography 50 Chem 355 Jasperse Chromatography BACKGROUND Chromatography is a powerful. Advantages for chromatography are its power and generality (not limited to liquids or solids or the need. Chromatography Every type of chromatography depends on the distribution of a substance between two phases

Jasperse, Craig P.

188

Comparison of turbulent-flow chromatography with automated solid-phase extraction in 96-well plates and liquid-liquid extraction used as plasma sample preparation techniques for liquid chromatography-tandem mass spectrometry.  

PubMed

Turbulent flow chromatography (TFC) combined with the high selectivity and sensitivity of tandem mass spectrometry (MS-MS) is a new technique for the fast direct analysis of drugs from crude plasma. TFC in the 96-well plate format reduces significantly the time required for sample clean-up in the laboratory. For example, for 100 samples the workload for a technician is reduced from about 8 h by a manual liquid-liquid extraction (LLE) assay to about 1 h in the case of TFC. Sample clean-up and analysis are performed on-line on the same column. Similar chromatographic performance and validation results were achieved using HTLC Turbo-C18 columns (Cohesive Technologies) and Oasis HLB extraction columns (Waters). One 96-well plate with 96 plasma samples is analyzed within 5.25 h, corresponding to 3.3 min per sample. Compared to this LLE and analysis of 96 samples takes about 16 h. Two structurally different and highly protein bound compounds, drug A and drug B, were analyzed under identical TFC conditions and the assays were fully validated for the application to toxicokinetics studies (compliant with Good Laboratory Practices-GLP). The limit of quantitation was 1.00 microg/l and the linear working range covered three orders of magnitude for both drugs. In the case of drug A the quality of analysis by TFC was similar to the reference LLE assay and slightly better than automated solid-phase extraction in 96-well plates. The accuracy was -3.1 to 6.7% and the precision was 3.1 to 6.8% in the case of drug A determined for dog plasma by TFC-MS-MS. For drug B the accuracy was -3.7 to 3.5% and the precision was 1.6 to 5.4% for rat plasma, which is even slightly better than what was achieved with the validated protein precipitation assay. PMID:10497925

Zimmer, D; Pickard, V; Czembor, W; Müller, C

1999-08-27

189

Triple acting radial seal  

DOEpatents

A triple acting radial seal used as an interstage seal assembly in a gas turbine engine, where the seal assembly includes an interstage seal support extending from a stationary inner shroud of a vane ring, the interstage seal support includes a larger annular radial inward facing groove in which an outer annular floating seal assembly is secured for radial displacement, and the outer annular floating seal assembly includes a smaller annular radial inward facing groove in which an inner annular floating seal assembly is secured also for radial displacement. A compliant seal is secured to the inner annular floating seal assembly. The outer annular floating seal assembly encapsulates the inner annular floating seal assembly which is made from a very low alpha material in order to reduce thermal stress.

Ebert, Todd A (West Palm Beach, FL); Carella, John A (Jupiter, FL)

2012-03-13

190

Methods and apparatus for radially compliant component mounting  

DOEpatents

Methods and apparatus for a mounting assembly for a liner of a gas turbine engine combustor are provided. The combustor includes a combustor liner and a radially outer annular flow sleeve. The mounting assembly includes an inner ring surrounding a radially outer surface of the liner and including a plurality of axially extending fingers. The mounting assembly also includes a radially outer ring coupled to the inner ring through a plurality of spacers that extend radially from a radially outer surface of the inner ring to the outer ring.

Bulman, David Edward (Cincinnati, OH); Darkins, Jr., Toby George (Loveland, OH); Stumpf, James Anthony (Columbus, IN); Schroder, Mark S. (Greenville, SC); Lipinski, John Joseph (Simpsonville, SC)

2012-03-27

191

Periostin, discovered by nano-flow liquid chromatography and mass spectrometry, is a novel marker of diabetic retinopathy  

SciTech Connect

Research highlights: {yields} In proliferative membrane and epiretinal membrane specimens, the numbers of proteins are 225 and 154, respectively, and 123 proteins are common to both. {yields} Periostin and thrombospondin-1 proteins are unique to the proliferative membrane specimens. {yields} The expression of periostin is significantly up-regulated in proliferative membrane specimens. -- Abstract: Diabetes can lead to serious microvascular complications including proliferative diabetic retinopathy (PDR), the leading cause of blindness in adults. Recent studies using gene array technology have attempted to apply a hypothesis-generating approach to elucidate the pathogenesis of PDR, but these studies rely on mRNA differences, which may or may not be related to significant biological processes. To better understand the basic mechanisms of PDR and to identify potential new biomarkers, we performed shotgun liquid chromatography (LC)/tandem mass spectrometry (MS/MS) analysis on pooled protein extracts from neovascular membranes obtained from PDR specimens and compared the results with those from non-vascular epiretinal membrane (ERM) specimens. We detected 226 distinct proteins in neovascular membranes and 154 in ERM. Among these proteins, 102 were specific to neovascular membranes and 30 were specific to ERM. We identified a candidate marker, periostin, as well as several known PDR markers such as pigment epithelium-derived factor (PEDF). We then performed RT-PCR using these markers. The expression of periostin was significantly up-regulated in proliferative membrane specimens. Periostin induces cell attachment and spreading and plays a role in cell adhesion. Proteomic analysis by LC/MS/MS, which permits accurate quantitative comparison, was useful in identifying new candidates such as periostin potentially involved in the pathogenesis of PDR.

Takada, Michiya [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan)] [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan); Ban, Yoshiyuki, E-mail: yshyban@yahoo.co.jp [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan)] [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan); Yamamoto, Gou [Department of Oral Pathology and Diagnosis, School of Dentistry, Showa University, Tokyo (Japan)] [Department of Oral Pathology and Diagnosis, School of Dentistry, Showa University, Tokyo (Japan); Ueda, Toshihiko; Saito, Yuta; Nishimura, Eiichi; Fujisawa, Kunimi; Koide, Ryohei [Department of Ophthalmology, Showa University School of Medicine, Tokyo (Japan)] [Department of Ophthalmology, Showa University School of Medicine, Tokyo (Japan); Mizutani, Masakazu; Kozawa, Tadahiko; Shiraishi, Yuji [Kozawa Eye Hospital and Diabetes Center, Ibaraki-ken (Japan)] [Kozawa Eye Hospital and Diabetes Center, Ibaraki-ken (Japan); Bando, Yasuhiko [Biosys Technologies, Inc., Meguro, Tokyo (Japan)] [Biosys Technologies, Inc., Meguro, Tokyo (Japan); Tachikawa, Tetsuhiko [Department of Oral Pathology and Diagnosis, School of Dentistry, Showa University, Tokyo (Japan)] [Department of Oral Pathology and Diagnosis, School of Dentistry, Showa University, Tokyo (Japan); Hirano, Tsutomu [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan)] [Division of Diabetes, Metabolism and Endocrinology, Department of Internal Medicine, Showa University School of Medicine, Tokyo (Japan)

2010-08-20

192

Exclusion Chromatography  

NSDL National Science Digital Library

This site contains a brief description of the separation mechanism in size exclusion chromatography. The picture helps visualize the separation, but the site features a simplified and idealized presentation useful for students new to the concept.

Kimball, John W.

193

Affinity Chromatography  

NSDL National Science Digital Library

Using exposition, graphics, and commercial videos, this module teaches the theory and application of affinity chromatography in the characterization of proteins, nucleic acids, and other biochemical/biomedical systems. Problems and application examples support the tutorial material.

194

Gas Chromatography  

NSDL National Science Digital Library

This is a website from the US Environmental Protection Agency that explains Gas Chromatography for those interested in environmental analysis. The level of the material assumes some user background in the field.

195

Active flow management in preparative chromatographic separations: a preliminary investigation into enhanced separation using a curtain flow inlet fitting and segmented flow outlet fitting.  

PubMed

Active flow management in the form of curtain flow sample introduction and segmented outlet flow control has been shown to enable sample to elute through a chromatography column under the principles of the "infinite diameter column". Such an elution process avoids the detrimental effects of the heterogeneity of particle-packed chromatographic columns by injecting the sample directly into the radial core region of the column, thus avoiding wall effects. The process described herein illustrates how the principles of the infinite diameter column can be applied using conventional injection devices suitable for long-term analysis that requires robust protocols. Using this approach, sensitivity in separation was 2.5 times greater than conventional chromatography, yielding a product at twice the concentration. Benefits of curtain flow injection are thus relevant to both preparative-scale and analytical-scale separations. PMID:22228597

Camenzuli, Michelle; Ritchie, Harald J; Ladine, James R; Shalliker, R Andrew

2012-02-01

196

Radial gate evaluation: Olympus Dam, Colorado  

SciTech Connect

The report presents a structural analysis of the radial gates of Olympus Dam in eastern Colorado. Five 20-foot wide by 17-foot high radial gates are used to control flow through the spillway at Olympus Dam. The spillway gates were designed in 1947. The gate arm assemblies consist of two separate wide flange beams, with a single brace between the arms. The arms pivot about a 4.0-inch diameter pin and bronze graphite-insert bushing. The pin is cantilevered from the pier anchor girder. The radial gates are supported by a pin bearing on a pier anchor birder bolted to the end of the concrete pier. The gates are operated by two-part wire rope 15,000-pound capacity hoise. Stoplog slots upstream of the radial gates are provided in the concrete piers. Selected drawings of the gates and hoists are located in appendix A.

NONE

1997-06-01

197

Chiral magnetic microspheres purified by centrifugal field flow fractionation and microspheres magnetic chiral chromatography for benzoin racemate separation.  

PubMed

Separation of enantiomers still remains a challenge due to their identical physical and chemical properties in a chiral environment, and the research on specific chiral selector along with separation techniques continues to be conducted to resolve individual enantiomers. In our laboratory the promising magnetic chiral microspheres Fe3O4@SiO2@cellulose-2, 3-bis (3,5-dimethylphenylcarbamate) have been developed to facilitate the resolution using both its magnetic property and chiral recognition ability. In our present studies this magnetic chiral selector was first purified by centrifuge field flow fractionation, and then used to separate benzoin racemate by a chromatographic method. Uniform-sized and masking-impurity-removed magnetic chiral selector was first obtained by field flow fractionation with ethanol through a spiral column mounted on the type-J planetary centrifuge, and using the purified magnetic chiral selector, the final chromatographic separation of benzoin racemate was successfully performed by eluting with ethanol through a coiled tube (wound around the cylindrical magnet to retain the magnetic chiral selector as a stationary phase) submerged in dry ice. In addition, an external magnetic field facilitates the recycling of the magnetic chiral selector. PMID:23891368

Tian, Ailin; Qi, Jing; Liu, Yating; Wang, Fengkang; Ito, Yoichiro; Wei, Yun

2013-08-30

198

Radial heat flux transformer  

NASA Technical Reports Server (NTRS)

Unit moves heat radially from small diameter shell to larger diameter shell, or vice versa, with negligible temperature drop, making device useful wherever heating or cooling of concentrically arranged materials, substances, and structures is desired.

Basiulis, A.; Buzzard, R. J.

1971-01-01

199

Radial turbine cooling  

NASA Technical Reports Server (NTRS)

The technology of high temperature cooled radial turbines is reviewed. Aerodynamic performance considerations are described. Heat transfer and structural analysis are addressed, and in doing so the following topics are covered: cooling considerations, hot side convection, coolant side convection, and rotor mechanical analysis. Cooled rotor concepts and fabrication are described, and the following are covered in this context: internally cooled rotor, hot isostatic pressure bonded rotor, laminated rotor, split blade rotor, and the NASA radial turbine program.

Roelke, Richard J.

1992-01-01

200

Validation and application of micro flow liquid chromatography-tandem mass spectrometry for the determination of pesticide residues in fruit jams.  

PubMed

In this study, a very sensitive method was validated to determine pesticides residues in fruit jams using micro flow liquid chromatography-tandem mass spectrometry (µLC-MS/MS). A slurry of the fruit jams and water was prepared to yield homogeneous samples. Because of the high sensitivity achieved with the µLC-MS/MS equipment and to minimize matrix effects, the QuEChERS extracts were diluted 30-fold before the analysis. The validation was performed analyzing spiked samples at 9 and 45µgkg(-1) (n=5). The method met validation criteria of 70-120% recovery and RSD?20% for 92% of the 107 pesticides evaluated. The reporting limit (RL) was 9 and 45µgkg(-1) for respectively 66% and 26% of the analytes, 5% of the compounds did not fulfill the requirements for validation and 3% were not detected at the studied concentrations. The validated method was applied to the analysis of 51 different fruit jam samples from Brazil and Spain and pesticide residues were detected in 41 samples, 26 of which contained at least one pesticide at concentration >10µgkg(-1). PMID:25618688

Reichert, Bárbara; Pizzutti, Ionara Regina; Costabeber, Ijoni Hilda; Uclés, Ana; Herrera, Sonia; Fernández-Alba, Amadeo R

2015-03-01

201

Development of a multiplex flow-through immunoaffinity chromatography test for the on-site screening of 14 sulfonamide and 13 quinolone residues in milk.  

PubMed

In this paper, a rapid and sensitive multiplex flow-through immunoaffinity chromatography test (FTIACT) was developed for the on-site screening of 14 sulfonamide and 13 quinolone residues in milk. The developed FTIACT method combines the purification, preconcentration and immunochemical detection of multiple antibiotics on the sepharose gel test layers. The use of liposome-encapsulated quantum dots (LQDs) with the FTIACT method exhibited the best results, with limits of detection (LODs) of 1 and 0.5ng/mL for the sulfonamides (SAs) and quinolones (QNs), respectively, through qualitative analysis (visual detection by the naked eye). In order to achieve low detection limit, the color intensity of the images were converted into relative optical density values to enable a quantitative evaluation. Quantitative analysis of the samples enabled the detection of SAs (0.13ng/mL) and QNs (0.062ng/mL) in spiked milk samples. The FTIACT described in this work shows promise as a multiplex immunoassay for the qualitative and quantitative screening of multiple chemical residues in milk. PMID:25460892

Jiang, Wenxiao; Beloglazova, Natalia V; Wang, Zhanhui; Jiang, Haiyang; Wen, Kai; de Saeger, Sarah; Luo, Pengjie; Wu, Yongning; Shen, Jianzhong

2015-04-15

202

Development of an on-line extraction turbulent flow chromatography tandem mass spectrometry method for cassette analysis of Caco-2 cell based bi-directional assay samples.  

PubMed

Caco-2 cells are frequently used for screening compounds for their permeability characteristics and P-glycoprotein (P-gp) interaction potential. Bi-directional permeability studies performed on Caco-2 cells followed by analysis by HPLC-UV or LC-MS method constitutes the "method of choice" for the functional assessment of efflux characteristics of a test compound. A high throughput LC-MS/MS method has been developed using on-line extraction turbulent flow chromatography coupled to tandem mass spectrometric detection to analyze multiple compounds present in Hanks balanced salt solution in a single analytical run. All standard curves (P-gp substrates: quinidine, etoposide, rhodamine 123, dexamethasone, and verapamil and non-substrates: metoprolol, sulfasalazine, propranolol, nadolol, and furosemide) were prepared in a cassette mode (ten-in-one) while Caco-2 cell incubations were performed both in discreet mode and in cassette mode. The standard curve range for most compounds was 10-2500 nM with regression coefficients (R(2)) greater than 0.99 for all compounds. The applicability and reliability of the analysis method was evaluated by successful demonstration of efflux ratio greater than 1 for the P-gp substrates studied in the Caco-2 cell model. The use of cassette mode analysis through selected reaction monitoring mass spectrometry presents an attractive option to increase the throughput, sensitivity, selectivity, and efficiency of the model over discreet mode UV detection. PMID:16307910

Smalley, James; Kadiyala, Pathanjali; Xin, Baomin; Balimane, Praveen; Olah, Timothy

2006-01-18

203

Simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater using low pressure ion chromatography combined with flow injection spectrophotometry.  

PubMed

Trivalent and hexavalent chromium have been successfully separated and determined using low pressure ion chromatography combined with flow injection spectrophotometric analysis (LPIC-FIA). A column packed with crosslinking starch microspheres was used for on-line separation of Cr(III) from Cr(VI) in a flow-injection system because of its absorptive effect on Cr(III). To determine the concentration of Cr(III) and Cr(VI) in samples, we used 3.0 mmol/L nitric acid to elute adsorbed Cr(III) from the column and then used ceric sulfate-sulfuric acid as oxidant to convert all Cr(III) into Cr(VI). Then, Cr(VI) directly came from the samples and Cr(VI) came from Cr(III) successively formed a amaranthine complex with diphenycarbazide and the complex shows a maximum absorption at 530 nm. Analytical parameters including the concentration of eluent and oxidant solution, oxidizing temperature, length of oxidizing reaction coil, reaction coil and injection coil, interfering effects, etc., were optimized. The limit of detection was 1.25 ?g/L for Cr(VI) and 3.76 ?g/L for Cr(III). The linear relationship between absorption with the concentration of Cr(VI) and Cr(III) was 0.001-1.000 mg/L and 0.030-1.000 mg/L with correlation coefficients of 0.9995 and 0.9994, respectively. The relative standard deviation of Cr(VI) and Cr(III) was 1.21% and 1.66%, respectively (n=10). Major cations and anions did not show any interference. We validated this method through certified reference materials and through measuring the recovery in tannery wastewater. PMID:22209249

Chen, Shujuan; Zhang, Xinshen; Yu, Lingyun; Wang, Li; Li, Hui

2012-03-01

204

On-line pretreatment and determination of parabens in cosmetic products by combination of flow injection analysis, solid-phase extraction and micellar electrokinetic chromatography.  

PubMed

A convenient and automated method for on-line pretreatment and determination of three parabens (i.e. methyl, ethyl and propyl p-hydroxybenzoate) in cosmetic products is proposed by using flow injection analysis (FIA), solid-phase extraction (SPE) and micellar electrokinetic chromatography (MEKC). An improved split-flow interface is used to couple SPE on C(8)-bonded silica with MEKC separation, which can avoid running buffer contamination and reduce buffer consumption, especially, containing expensive reagents. The analytes are loaded onto a C(8) column at 0.6 mL/min for 60s and eluted with a mixed eluent of 40% (v/v) 10 mmol/L sodium tetraborate buffer (pH 9.3) and 60% (v/v) ethanol at 0.75 mL/min. The MEKC separation is accomplished with a running buffer of 20 mmol/L sodium tetraborate (pH 9.3) containing 100 mmol/L sodium dodecyl sulfate (SDS) at 15 kV. For butyl p-hydroxybenzoate did not be detected in the cosmetic products, it was used as an internal standard (IS) added into the real samples. This FIA-SPE-MEKC method using IS allows the sample separation within 12 min and the sample throughput of five samples per hour with the relative standard deviation (R.S.D.) less than 2.3% (n=5). The limits of detection (LOD) are in the range from 0.07 to 0.1 microg/mL (S/N=3 and n=11). The proposed method has been used to determine three parabens in real cosmetic products satisfactorily. PMID:18371792

Han, Fang; He, You-Zhao; Yu, Chang-Zhu

2008-02-15

205

Simultaneous determination of Cr(III) and Cr(VI) in tannery wastewater using low pressure ion chromatography combined with flow injection spectrophotometry  

NASA Astrophysics Data System (ADS)

Trivalent and hexavalent chromium have been successfully separated and determined using low pressure ion chromatography combined with flow injection spectrophotometric analysis (LPIC-FIA). A column packed with crosslinking starch microspheres was used for on-line separation of Cr(III) from Cr(VI) in a flow-injection system because of its absorptive effect on Cr(III). To determine the concentration of Cr(III) and Cr(VI) in samples, we used 3.0 mmol/L nitric acid to elute adsorbed Cr(III) from the column and then used ceric sulfate-sulfuric acid as oxidant to convert all Cr(III) into Cr(VI). Then, Cr(VI) directly came from the samples and Cr(VI) came from Cr(III) successively formed a amaranthine complex with diphenycarbazide and the complex shows a maximum absorption at 530 nm. Analytical parameters including the concentration of eluent and oxidant solution, oxidizing temperature, length of oxidizing reaction coil, reaction coil and injection coil, interfering effects, etc., were optimized. The limit of detection was 1.25 ?g/L for Cr(VI) and 3.76 ?g/L for Cr(III). The linear relationship between absorption with the concentration of Cr(VI) and Cr(III) was 0.001-1.000 mg/L and 0.030-1.000 mg/L with correlation coefficients of 0.9995 and 0.9994, respectively. The relative standard deviation of Cr(VI) and Cr(III) was 1.21% and 1.66%, respectively (n = 10). Major cations and anions did not show any interference. We validated this method through certified reference materials and through measuring the recovery in tannery wastewater.

Chen, Shujuan; Zhang, Xinshen; Yu, Lingyun; Wang, Li; Li, Hui

2012-03-01

206

Anal. Chem. 1994,66,168-176 Classification of Countercurrent Chromatography Solvent  

E-print Network

Anal. Chem. 1994,66,168-176 Classification of Countercurrent Chromatography Solvent Systems Cedex 05, France Solvent systems used for countercurrent chromatography (CCC) have been classified predictionof the experimental flow behavior in CCC. Countercurrent chromatography (CCC) is a separation method

Wesfreid, José Eduardo

207

A new physical model based on cascading column experiments to reproduce the radial flow and transport of micro-iron particles  

NASA Astrophysics Data System (ADS)

In the field of aquifer restoration and civil engineering, fluids and suspensions are delivered in porous media via well injection. The flow field resulting around the well is three-dimensional. Since two and three-dimensional experiments which can be used to reproduce such flow fields are, although accurate, extremely elaborate and time consuming, the authors suggest to substitute them by a cascade of interdependent, one-dimensional (column) experiments. The new method is used to simulate the injection in aquifers of micro-iron particles dispersed in a shear thinning gel of guar gum and allows the prediction of iron particle distribution around the well and of injection pressure. The method respects the mass balance at the field scale and its predictions are in good agreement with those of a mathematical model proposed in the literature. The method is consistent with the Triad Approach, a way to improve remediation efficiency proposed by the U.S. Environmental Protection Agency. The representativeness of the proposed tests combined with their simplicity and relative inexpensiveness make this new method applicable and useful in the planning and design of real remediation.

Comba, Silvia; Braun, Jürgen

2012-10-01

208

Determination of catecholamines by flow-injection analysis and high-performance liquid chromatography with chemiluminescence detection.  

PubMed

A chemiluminescence (CL) detection of catecholamines [norepinephrine (NE), epinephrine (E), dopamine (DA) and L-dopa (LD)] is described for the flow-injection (FI) and high-performance liquid chromatographic (HPLC) determination of these compounds. The detection method is based on the inhibition effect of catecholamines (CAs) on the CL reaction of luminol with iodine in the alkaline medium. The proposed FI method allows the determination of CAs in pharmaceutical preparations for the purpose of drug quality control. The calibration curves show good linearity in the concentration range of: 1.1-20.0 microg l(-1) (NE), 0.5-5.0 microg l(-1) (E), 0.6-9.0 microg l(-1) (DA) and 0.6-10.0 microg l(-1) (LD). The limits of detection (defined as a signal-to-noise ratio of 3) are: 0.34 microg l(-1) (NE), 0.15 microg l(-1) (E) and 0.18 microg l(-1) (DA, LD). The HPLC procedure was successfully applied for the determination of catecholamines (NE, E, DA) in human urine after solid-phase extraction (SPE). In a simple run time CAs can be determined in 20 min. The chromatographic linear ranges are: 5.0-72.0 microg l(-1) (NE), 5.0-48.0 microg l(-1) (E) and 5.0-96.0 microg l(-1) (DA). The limits of detection for three urinary CAs are: 0.71 microg l(-1) (NE), 0.26 microg l(-1) (E) and 0.73 microg l(-1) (DA). PMID:17289328

Nalewajko, Edyta; Wiszowata, Aneta; Koj?o, Anatol

2007-04-11

209

Spotting Chromatography  

NSDL National Science Digital Library

In this mini-lab students will use chromatography to compare the mobile phase and the stationary phases of different inks used in marking pens. They will also determine the polarity of the solvents and inks. Finally, the students will use their calculated information to solve a crime.

210

Ion chromatography  

Microsoft Academic Search

Ion chromatography makes it possible to separate and measure low concentrations of up to 8 or 10 different anions in a single chromatographic run that takes only a few minutes. The method also works well for cations. Alkali metal ions, ammonium, magnesium, calcium, strontium, and a growing list of other metal cations and amine cations can also be rapidly separated

James S. Fritz

1987-01-01

211

Paper Chromatography  

NSDL National Science Digital Library

This is a site with experiments that provide a brief introduction to the idea of separation of components in a mixture and a set of instructions for students for separating colored compounds by paper chromatography (on coffee filters). The appropriate audience would be students in a high-school or introductory, non major college chemistry class.

Reeves, James H.

2011-05-19

212

Gas Chromatography  

NSDL National Science Digital Library

This site contains a brief introduction to the concepts of injection and detection in gas chromatography, focusing on the split/splitless injection port and flame ionization detectors. The treatment is similar to that in analytical chemistry textbooks, and includes detailed illustrations.

213

Radial turbine cooling  

NASA Technical Reports Server (NTRS)

Radial turbines have been used extensively in many applications including small ground based electrical power generators, automotive engine turbochargers and aircraft auxiliary power units. In all of these applications the turbine inlet temperature is limited to a value commensurate with the material strength limitations and life requirements of uncooled metal rotors. To take advantage of all the benefits that higher temperatures offer, such as increased turbine specific power output or higher cycle thermal efficiency, requires improved high temperature materials and/or blade cooling. Extensive research is on-going to advance the material properties of high temperature superalloys as well as composite materials including ceramics. The use of ceramics with their high temperature potential and low cost is particularly appealing for radial turbines. However until these programs reach fruition the only way to make significant step increases beyond the present material temperature barriers is to cool the radial blading.

Roelke, Richard J.

1992-01-01

214

Chemical evolution with radial mixing  

E-print Network

Models of the chemical evolution of our Galaxy are extended to include radial migration of stars and flow of gas through the disc. The models track the production of both iron and alpha elements. A model is chosen that provides an excellent fit to the metallicity distribution of stars in the Geneva-Copenhagen survey (GCS) of the solar neighbourhood, and a good fit to the local Hess diagram. The model provides a good fit to the distribution of GCS stars in the age-metallicity plane although this plane was not used in the fitting process. Although this model's star-formation rate is monotonic declining, its disc naturally splits into an alpha-enhanced thick disc and a normal thin disc. In particular the model's distribution of stars in the ([O/Fe],[Fe/H]) plane resembles that of Galactic stars in displaying a ridge line for each disc. The thin-disc's ridge line is entirely due to stellar migration and there is the characteristic variation of stellar angular momentum along it that has been noted by Haywood in survey data. Radial mixing of stellar populations with high sigma_z from inner regions of the disc to the solar neighbourhood provides a natural explanation of why measurements yield a steeper increase of sigma_z with age than predicted by theory. The metallicity gradient in the ISM is predicted to be steeper than in earlier models, but appears to be in good agreement with data for both our Galaxy and external galaxies. The models are inconsistent with a cutoff in the star-formation rate at low gas surface densities. The absolute magnitude of the disc is given as a function of time in several photometric bands, and radial colour profiles are plotted for representative times.

Ralph Schoenrich; James Binney

2009-03-06

215

Radial Artery Catheterization  

MedlinePLUS

... because of a blood clot forming in the artery. Blood thinners given during the procedure help to prevent ... in less than 2% of cases. When radial artery occlusion does occur, it generally causes no issue for the hand because there are redundant blood supplies to the hand. Previous Section Next Section ...

216

Chromatography Lab  

NSDL National Science Digital Library

To increase students' awareness of possible invisible pollutants in drinking water sources, students perform an exciting lab requiring them to think about how solutions and mixtures exist even in unsuspecting places such as ink. They use alcohol and chromatography paper to separate the components of black and colored marker ink. Students witness first-hand how components of a solution can be separated, even when those individual components are not visible in solution.

GK-12 Program,

217

Variable stator radial turbine  

NASA Technical Reports Server (NTRS)

A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.

Rogo, C.; Hajek, T.; Chen, A. G.

1984-01-01

218

Single Radial Immunodiffusion  

Microsoft Academic Search

\\u000a Single radial immunodiffusion is used extensively for the quantitative estimation of antigens (1). In this method, the antigen-antibody precipitation is made more sensitive than in double immunodiffusion (see Chapter 135) by the incorporation of the antiserum in the agar solution before the gel is made (2). Thus, the antiserum is uniformly distributed throughout the agar gel. Antigen is then allowed

Graham S. Bailey

219

Radial pressure flange seal  

DOEpatents

This invention provides an all metal seal for vacuum or pressure vessels or systems. This invention does not use gaskets. The invention uses a flange which fits into a matching groove. Fluid pressure is applied in a chamber in the flange causing at least one of the flange walls to radially press against a side of the groove creating the seal between the flange wall and the groove side. 5 figs.

Batzer, T.H.; Call, W.R.

1989-01-24

220

Radial pressure flange seal  

DOEpatents

This invention provides an all metal seal for vacuum or pressure vessels or systems. This invention does not use gaskets. The invention uses a flange which fits into a matching groove. Fluid pressure is applied in a chamber in the flange causing at least one of the flange walls to radially press against a side of the groove creating the seal between the flange wall and the groove side.

Batzer, Thomas H. (Livermore, CA); Call, Wayne R. (Tracy, CA)

1989-01-01

221

Radial Field Piezoelectric Diaphragms  

NASA Technical Reports Server (NTRS)

A series of active piezoelectric diaphragms were fabricated and patterned with several geometrically defined Inter-Circulating Electrodes "ICE" and Interdigitated Ring Electrodes "ICE". When a voltage potential is applied to the electrodes, the result is a radially distributed electric field that mechanically strains the piezoceramic along the Z-axis (perpendicular to the applied electric field). Unlike other piezoelectric bender actuators, these Radial Field Diaphragms (RFDs) strain concentrically yet afford high displacements (several times that of the equivalent Unimorph) while maintaining a constant circumference. One of the more intriguing aspects is that the radial strain field reverses itself along the radius of the RFD while the tangential strain remains relatively constant. The result is a Z-deflection that has a conical profile. This paper covers the fabrication and characterization of the 5 cm. (2 in.) diaphragms as a function of poling field strength, ceramic thickness, electrode type and line spacing, as well as the surface topography, the resulting strain field and displacement as a function of applied voltage at low frequencies. The unique features of these RFDs include the ability to be clamped about their perimeter with little or no change in displacement, the environmentally insulated packaging, and a highly repeatable fabrication process that uses commodity materials.

Bryant, R. G.; Effinger, R. T., IV; Copeland, B. M., Jr.

2002-01-01

222

Fundamentals of preparative and nonlinear chromatography  

SciTech Connect

The second edition of Fundamentals of Preparative and Nonlinear Chromatography is devoted to the fundamentals of a new process of purification or extraction of chemicals or proteins widely used in the pharmaceutical industry and in preparative chromatography. This process permits the preparation of extremely pure compounds satisfying the requests of the US Food and Drug Administration. The book describes the fundamentals of thermodynamics, mass transfer kinetics, and flow through porous media that are relevant to chromatography. It presents the models used in chromatography and their solutions, discusses the applications made, describes the different processes used, their numerous applications, and the methods of optimization of the experimental conditions of this process.

Guiochon, Georges A [ORNL; Felinger, Attila [ORNL; Katti, Anita [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Shirazi, Dean G [unknown

2006-02-01

223

Bisphenol A determination in baby bottles by chemiluminescence enzyme-linked immunosorbent assay, lateral flow immunoassay and liquid chromatography tandem mass spectrometry.  

PubMed

Two immunoassays, a Lateral Flow ImmunoAssay (LFIA) based on colloidal gold nanoparticle labels and an indirect competitive chemiluminescence enzyme-linked immunosorbent assay (CL-ELISA), were developed and a high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was optimized to assess the possible release of bisphenol A (BPA, 4,4'-isopropylidenediphenol) from different plastic baby bottles treated with simulating solutions. Coating conjugate concentration, anti-BPA antibody dilution, incubation time of the primary and secondary antibodies, and tolerance to different organic solvents were optimized to obtain the best performance of the ELISA with chemiluminescent end-point detection. The influence of different buffers on LFIA performance was also evaluated. Both methods showed good repeatability (mean CV value around 13%) and sensitivity. Reproducibility tests for CL-ELISA gave a mean CV value of about 25%. The IC50 and Limit of Detection (LOD) values of CL-ELISA were 0.2 and 0.02 ng mL(-1), respectively. The LOD of LFIA was 0.1 ?g mL(-1). A LC-MS/MS method was also optimized. The separation was performed in a C18 column with a triple-quadrupole mass spectrometer with electrospray ionisation interface. The method showed a good linearity in the range 2 to 500 ng mL(-1), with a regression coefficient of 0.998. In the simulating solutions the detection and quantification limits, calculated by the signal to noise level of 3 (S/N = 3), were 5.8 ng mL(-1) and 17.4 ng mL(-1), respectively. This limit of quantification was about 3 and 35 times lower than the permitted limits set by the official method CEN/TS 13130-13 (0.05 ?g mL(-1)) and by the Directive 2004/19/EC (0.6 ?g mL(-1)), respectively. The methods were applied to determine BPA release from baby bottles, performing repeated procedures according to EU and national regulations. The results demonstrated that no BPA migration from the tested plastic materials occurred with only one exception. The migrated amount, above the regulatory limits, was detected by all the mentioned assays. PMID:24223419

Maiolini, Elisabetta; Ferri, Elida; Pitasi, Agata Laura; Montoya, Angel; Di Giovanni, Manuela; Errani, Ermanno; Girotti, Stefano

2014-01-01

224

Design and performance of a new continuous-flow sample-introduction system for flame infrared-emission spectrometry: Applications in process analysis, flow injection analysis, and ion-exchange high-performance liquid chromatography.  

PubMed

A new sample introduction system for the analysis of continuously flowing liquid streams by flame infrared-emission (FIRE) spectrometry has been developed. The system uses a specially designed purge cell to strip dissolved CO(2) from solution into a hydrogen gas stream that serves as the fuel for a hydrogen/air flame. Vibrationally excited CO(2) molecules present in the flame are monitored with a simple infrared filter (4.4 mum) photometer. The new system can be used to introduce analytes as a continuous liquid stream (process analysis mode) or on a discrete basis by sample injection (flow injection analysis mode). The key to the success of the method is the new purge-cell design. The small internal volume of the cell minimizes problems associated with purge-cell clean-out and produces sharp, reproducible signals. Spent analytical solution is continuously drained from the cell, making cell disconnection and cleaning between samples unnecessary. Under the conditions employed in this study, samples could be analyzed at a maximum rate of approximately 60/h. The new sample introduction system was successfully tested in both a process analysis- and a flow injection analysis mode for the determination of total inorganic carbon in Waco tap water. For the first time, flame infrared-emission spectrometry was successfully extended to non-volatile organic compounds by using chemical pretreatment with peroxydisulfate in the presence of silver ion to convert the analytes into dissolved carbon dioxide, prior to purging and detection by the FIRE radiometer. A test of the peroxydisulfate/Ag(+) reaction using six organic acids and five sugars indicated that all 11 compounds were oxidized to nearly the same extent. Finally, the new sample introduction system was used in conjunction with a simple filter FIRE radiometer as a detection system in ion-exchange high-performance liquid chromatography. Ion-exchange chromatograms are shown for two aqueous mixtures, one containing six organic acids and the second containing six mono-, di-, and trisaccharides. PMID:18965720

Lam, C K; Zhang, Y; Busch, M A; Busch, K W

1993-06-01

225

Experimental feasibility study of radial injection cooling of three-pad radial air foil bearings  

NASA Astrophysics Data System (ADS)

Air foil bearings use ambient air as a lubricant allowing environment-friendly operation. When they are designed, installed, and operated properly, air foil bearings are very cost effective and reliable solution to oil-free turbomachinery. Because air is used as a lubricant, there are no mechanical contacts between the rotor and bearings and when the rotor is lifted off the bearing, near frictionless quiet operation is possible. However, due to the high speed operation, thermal management is one of the very important design factors to consider. Most widely accepted practice of the cooling method is axial cooling, which uses cooling air passing through heat exchange channels formed underneath the bearing pad. Advantage is no hardware modification to implement the axial cooling because elastic foundation structure of foil bearing serves as a heat exchange channels. Disadvantage is axial temperature gradient on the journal shaft and bearing. This work presents the experimental feasibility study of alternative cooling method using radial injection of cooling air directly on the rotor shaft. The injection speeds, number of nozzles, location of nozzles, total air flow rate are important factors determining the effectiveness of the radial injection cooling method. Effectiveness of the radial injection cooling was compared with traditional axial cooling method. A previously constructed test rig was modified to accommodate a new motor with higher torque and radial injection cooling. The radial injection cooling utilizes the direct air injection to the inlet region of air film from three locations at 120° from one another with each location having three axially separated holes. In axial cooling, a certain axial pressure gradient is applied across the bearing to induce axial cooling air through bump foil channels. For the comparison of the two methods, the same amount of cooling air flow rate was used for both axial cooling and radial injection. Cooling air flow rate was referenced to the rotor surface speed for radial injection cooling. The mass flow rates for the radial injection were 0.032, 0.0432, 0.054 and 0.068 Kg/min, which result in average injection speed of 150, 200, 250 and 300% of rotor surface speed. Several thermocouples were attached at various circumferential directions of the bearing sleeve, two plenums, bearing holder and ball bearing housings to collect the temperature data of the bearing at 30krpm under 10lb of load. Both axial cooling and radial injection are effective cooling mechanism and effectiveness of both cooling methods is directly proportional to the total mass flow rates. However, axial cooling is slightly more efficient in controlling the average temperature of the bearing sleeve, but results in higher thermal gradient of the shaft along the axial direction and also higher thermal gradient of the bearing sleeve along the circumferential direction compared to the radial injection cooling. The smaller thermal gradient of the radial injection cooling is due to the direct cooling effect of the shaft by impinging jets. While the axial cooling has an effect on only the bearing, the radial injection has a cooling effect on both the bearing sleeve and shaft. It is considered the radial injection cooling needs to be further optimized in terms of number of injection holes and their locations.

Shrestha, Suman K.

226

3D Velocity from 3D Doppler Radial Velocity J. L. Barron,1  

E-print Network

to compute local 3D velocity (local 3D optical flow). Radial velocity (measured by the Doppler effect3D Velocity from 3D Doppler Radial Velocity J. L. Barron,1 R. E. Mercer,1 X. Chen,1 P. Joe2 1 by a Doppler radar. We demonstrate the perfor- mance of our algorithms quantitatively on synthetic radial

Barron, John

227

Gas Chromatography  

NASA Astrophysics Data System (ADS)

Gas chromatography (GC) has many applications in the analysis of food products. GC has been used for the determination of fatty acids, triglycerides, cholesterol, gases, water, alcohols, pesticides, flavor compounds, and many more. While GC has been used for other food components such as sugars, oligosaccharides, amino acids, peptides, and vitamins, these substances are more suited to analysis by high performance liquid chromatography. GC is ideally suited to the analysis of volatile substances that are thermally stable. Substances such as pesticides and flavor compounds that meet these criteria can be isolated from a food and directly injected into the GC. For compounds that are thermally unstable, too low in volatility, or yield poor chromatographic separation due to polarity, a derivatization step must be done before GC analysis. The two parts of the experiment described here include the analysis of alcohols that requires no derivatization step, and the analysis of fatty acids which requires derivatization. The experiments specify the use of capillary columns, but the first experiment includes conditions for a packed column.

Qian, Michael C.

228

Chem 355 Jasperse Gas Chromatography-Mass Spectroscopy BACKGROUND Every type of chromatography depends on the distribution of a substance  

E-print Network

GC-MS 35 Chem 355 Jasperse Gas Chromatography-Mass Spectroscopy BACKGROUND Every type of chromatography depends on the distribution of a substance between two phases, a mobile phase and a stationary phase. Recall that in the liquid/solid chromatography the mobile phase was liquid flowing over

Jasperse, Craig P.

229

Radial parallel plate flow with mechanical agitation  

E-print Network

Computer processors have significant and rising cooling requirements, with electronics cooling estimated to consume 1% of global energy consumption. An integrated fan heat sink was designed to help alleviate this issue, ...

Crane, Jackson T

2013-01-01

230

Dielectrokinetic chromatography and devices thereof  

SciTech Connect

Disclosed herein are methods and devices for dielectrokinetic chromatography. As disclosed, the devices comprise microchannels having at least one perturber which produces a non-uniformity in a field spanning the width of the microchannel. The interaction of the field non-uniformity with a perturber produces a secondary flow which competes with a primary flow. By decreasing the size of the perturber the secondary flow becomes significant for particles/analytes in the nanometer-size range. Depending on the nature of a particle/analyte present in the fluid and its interaction with the primary flow and the secondary flow, the analyte may be retained or redirected. The composition of the primary flow can be varied to affect the magnitude of primary and/or secondary flows on the particles/analytes and thereby separate and concentrate it from other particles/analytes.

Chirica, Gabriela S; Fiechtner, Gregory J; Singh, Anup K

2014-04-22

231

Multielement characterization of metal-humic substances complexation by size exclusion chromatography, asymmetrical flow field-flow fractionation, ultrafiltration and inductively coupled plasma-mass spectrometry detection: a comparative approach.  

PubMed

The use of three different separation techniques, ultrafiltration (UF), high performance size exclusion chromatography (HPSEC) and asymmetrical flow field-flow fractionation (AsFlFFF), for the characterization of a compost leachate is described. The possible interaction of about 30 elements with different size fractions of humic substances (HS) has been investigated coupling these separation techniques with UV-vis absorption spectrophotometry and inductively coupled plasma-mass spectrometry (ICP-MS) as detection techniques. The organic matter is constituted by a polydisperse mixture of humic substances ranging from low molecular weights (around 1kDa) to significantly larger entities. Elements can be classified into three main groups with regard to their interaction with HS. The first group is constituted by primarily the monovalent alkaline metal ions and anionic species like B, W, Mo, As existing as oxyanions all being not significantly associated to HS. The second group consists of elements that are at least partly associated to a smaller HS size fraction (such as Ni, Cu, Cr and Co). A third group of mainly tri- and tetravalent metal ions like Al, Fe, the lanthanides, Sn and Th are rather associated to larger-sized HS fractions. The three separation techniques provide a fairly consistent size classification for most of the metal ions, even though slight disagreements were observed. The number-average molecular weight (Mn), the weight-average molecular weight (Mw) and the polydispersity (rho) parameters have been calculated both from AsFlFFF and HPSEC experiments and compared for HS and some metal-HS species. Differences in values can be partly explained by an overloading effect observed in the AsFlFFF experiments induced by electrostatic repulsion effects in the low ionic strength, high pH carrier solution. Size information obtained from ultrafiltration is not as resolved as for the other methods. Molecular weight cut-offs (MWCO) of the individual filter membranes refer to globular proteins and molecular weight information may therefore, deviate from that given by the other methods after calibration with polystyrene sulfonate (PSS) standards. PMID:16859692

Bolea, E; Gorriz, M P; Bouby, M; Laborda, F; Castillo, J R; Geckeis, H

2006-10-01

232

Atomic force microscope mediated chromatography  

NASA Astrophysics Data System (ADS)

An atomic force microscope (AFM) is presented as an instrument for rapid, miniaturized chromatography. The AFM is used to inject a sample, provide shear driven liquid flow over a functionalized substrate, and detect separated components. The components are then analyzed with surface enhanced Raman spectroscopy using AFM deposition of gold nanoparticles on the separated bands. This AFM mediated chromatography (AFM-MC) is demonstrated using lipophilic dyes and normal phase chemistry. A significant reduction in both size and separation time scales is achieved with 25 ?m length scale and 1 s separation times. AFM-MC has general applications to trace chemical analysis and microfluidics.

Anderson, M. S.

2013-02-01

233

Gas Chromatography  

NSDL National Science Digital Library

This video, distributed on YouTube by the Royal Society of Chemistry, is on the basic principles of Gas Chromatography. This video is a short primer which introduces the technique and instrumentation. There are many assumptions that are made in the presentation of this material, due to the fact the video is meant to be a basic introduction. The ultimate strength of this video is the general nature of the content that makes it appealing to a wide audience. The video may be most appropriate in a lower-level general education science course (i.e forensic science) or as a quick orientation video for instrumental analysis students. The GC-FID and GC-MS are highlighted. Running time for the video is 5:17.

234

Principles and Methods Chromatography  

E-print Network

Edition AC 18-1022-29 Principles and Methods Affinity Chromatography #12;Antibody Purification-1142-75 Protein Purification Handbook 18-1132-29 Ion Exchange Chromatography Principles and Methods 18-1114-21 Affinity Chromatography Principles and Methods 18-1022-29 Hydrophobic Interaction Chromatography Principles

Lebendiker, Mario

235

Thin-layer chromatography: challenges and opportunities  

Microsoft Academic Search

The purpose of this article is to identify core technologies with the potential to influence the development of thin-layer chromatography over the next decade or so. Core technologies are identified as: (i) methods to provide a constant and optimum mobile phase velocity (forced flow and electroosmotically-driven flow), (ii) video densitometry for recording multidimensional chromatograms, (iii) in situ scanning mass spectrometry,

Colin F. Poole

2003-01-01

236

Singular spectrum for radial trees  

E-print Network

We prove several results showing that absolutely continuous spectrum for the Laplacian on radial trees is a rare event. In particular, we show that metric trees with unbounded edges have purely singular spectrum and that generically (in the sense of Baire) radial trees have purely singular continuous spectrum.

Jonathan Breuer; Rupert L. Frank

2008-06-03

237

The history of radial glia.  

PubMed

Radial glial cells are now recognized as a transient population that serves as scaffolding for neuronal migration. The recognition of the existence and role of radial glia has not been smooth, and here we provide a brief historical overview on the pioneering studies on this subject. The histologists and embryologists Albert Kölliker and Wilhelm His performed seminal investigations on cortical morphogenesis in the last decades of the 19th century. However, the introduction of the silver impregnation Golgi technique, and its diffusion in the late 1880s, played a crucial role in the detection of radial glial processes. The radial arrangement of fibers emerging from the neuroepithelium lining the central canal was initially detected in the embryonic spinal cord by Camillo Golgi himself. The first Golgi impregnation of the cerebral cortex of mammalian fetuses was performed by Giuseppe Magini, who detected radial fibers extending from the ventricular neuroepithelium, and observed cells intercalated along these processes. Radial fibers, regarded as epithelial or ependymal processes, were then observed in the developing spinal cord and cerebral cortex by several investigators. Santiago Ramón y Cajal was the first to suggest that radial fibers were modified astrocytic processes functioning as a support during cortical histogenesis. Cajal acknowledged Magini's findings, but he criticized Magini's observations on the existence of neurons along radial fibers. With the advent of electron microscopy, the existence of radially arranged glial processes along which young neurons migrate was finally ascertained in the early 1970s by Pasko Rakic, thus opening a new era in the cellular and molecular biology of radial glia. PMID:10452351

Bentivoglio, M; Mazzarello, P

1999-07-15

238

Three-dimensional thin-layer chromatography  

NASA Astrophysics Data System (ADS)

A three-dimensional variation of planar chromatography is proposed and realized. In this new variation of planar chromatography, components of the mixture under investigation migrate under the action of the mobile phase flow in one direction, then in another direction at an angle to the first direction, and then in a third direction at an angle to the second direction; in this case, all elution processes are carried out using different volatile eluents and drying the plate between the three elution processes. Using the example of separation of a mixture of dyes, it is shown that three-dimensional planar chromatography is appropriate for practical purposes.

Berezkin, V. G.; Kulakova, N. Yu.

2009-11-01

239

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

PubMed

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

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

2010-04-23

240

Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis of nanomole  

E-print Network

Isotope-ratio-monitoring gas chromatography methods for high-precision isotopic analysis and a commercially available continuous-flow, gas chromatography interface (the Finnigan Gas Bench II). This work

Bebout, Gray E.

241

Effect of parallel segmented flow chromatography on the height equivalent to a theoretical plate III--influence of the column length, particle diameter, and the molecular weight of the analyte on the efficiency gain.  

PubMed

The effects of column length on performance in segmented flow chromatography were tested. Column efficiencies were measured for 4.6mm I.D. 3, 5, 7.5 and 10 cm long columns packed with 3.0 ?m Hypurity-C18 fully porous particles and of 4.6mm I.D. 5, 10, 15 and 25 cm long columns packed with 5 ?m Hypersil GOLD C18 particles. For each column length and particle type, two different configurations were tested: (1) both the inlet and outlet column endfittings were standard and (2) the inlet endfitting was standard but the outlet endfitting allowed parallel segmentation of the exiting flow into a central and a peripheral coaxial region. The segmentation flow ratio was set at 45% (for 3 ?m) and at 43% or 21% (for 5 ?m). Four samples were used, naphthalene, toluene, butylbenzene, and insulin, which has a ten times smaller diffusion coefficient than the small molecules. The column performance for the low molecular weight compound is significantly improved at velocities above the optimum value when the outlet flow rate is segmented because longitudinal diffusion and mass transfer resistance of this compound in the stationary phase are negligible sources of band broadening at reduced linear velocities between 5 and 25. At high flow rate (4 mL/min), the long-range eddy dispersion terms are about 3.9, 3.2, 2.6, and 1.8h unit lower for the 3, 5, 7.5 and 10 cm long columns, respectively. The longer the column, the lower the efficiency improvement because the border effects are smaller. This result was not systematically observed for the columns packed with 5 ?m particles because the transverse dispersion is larger. In contrast, the gain in column efficiency is marginal for insulin because the mass transfer mechanism of this compound is mostly controlled by the slow diffusivity of insulin across Hypurity-C18 particles. PMID:24529404

Gritti, Fabrice; Pynt, Jarrod; Soliven, Arianne; Dennis, Gary R; Shalliker, R Andrew; Guiochon, Georges

2014-03-14

242

The identification and quantification of a high molecular weight light stabilizer in polycarbonate by application of an online coupling of size exclusion chromatography in stopped flow mode with pyrolysis gas chromatography time of flight mass spectroscopy.  

PubMed

The identification and quantification of a high molecular weight light stabilizer (Uvinul 3030™) in an unknown polycarbonate sample was achieved through the application of SEC-Py-TOF-GCMS. A size exclusion column optimized to achieve resolution in the lower mass range was applied to allow the fractionation of an individual additive peak. A commercially available sampling interface was operated in stop flow mode and fractions were pyrolyzed to allow chromatographic separation of the fragments of the otherwise non-volatile stabilizer. After identification on the basis of accurate mass and elemental composition of the additive the quantification was compared using the available SEC-UV and SEC-PY-GC-TOFMS data. The resulting method provided a high degree of certainty in identification and flexibility in quantification expected to be applicable to other additives of similar volatilities or functional class. PMID:25160954

Brander, Eric; Wold, Christian

2014-10-01

243

Applying Simple Chromatography  

NSDL National Science Digital Library

This activity involves chemistry, mystery, colors, and measurement. Students observe the composition of various inks by separating them via water-based chromatography. Students use what they learn about chromatography to solve a mystery involving a suspic

John Eichinger

2009-05-15

244

Evaluation of Performance of Radial Collector Wells Using a Detailed Numerical Modeling Technique  

NASA Astrophysics Data System (ADS)

A detailed numerical modeling technique was developed to evaluate quantitatively and accurately performance of radial collector wells for large-capacity indirect intake of riverside groundwater. The detailed numerical modeling technique consists of the three components such as precise spatial discretization of complicated structures (a vertical collector well with radial arms) of radial collector wells, rigorous realization of actual pumping schemes (pumping water drained from radial arms to a vertical collector well) of radial collector wells, and integrated simulation of saturated-unsaturated groundwater flow. However, previous numerical simulation studies did not consider such complicated structures and actual pumping schemes of radial collector wells as well as unsaturated groundwater flow. Such a detailed numerical modeling technique is then numerically implemented into a generalized multidimensional groundwater flow and solute transport finite element model COFAT3D (Kim and Yeh, 2004~2012). Finally, a series of numerical simulations was performed using the detailed numerical modeling technique to evaluate impacts of specifications (length and number of radial arms) of a radial collector well on its performance (steady-state water intake rate) and efficiency (steady-state water intake rate per length of radial arms or per radial arm). The numerical simulation results show that the performance increases, whereas the efficiency initially increases and then decreases as the length or number of radial arms increases. It arises because hydrologic interference among radial arms begins to occur beyond a certain length and number of radial arms. Therefore, the numerical simulation results suggest that the detailed numerical modeling technique can be utilized as a robust tool or methodology to evaluate and to optimize performance and efficiency of radial collector wells for large-capacity indirect intake of riverside groundwater. This work was supported by the Program of Advanced Technology for Groundwater Development and Application in Riversides (Geowater+) funded by the Korea Agency for Infrastructure Technology Advancement (KAIA), Ministry of Land, Infrastructure and Transport, Republic of Korea.

Choi, S.; Park, S.; Kim, J.

2013-12-01

245

Chromatography: concepts and contrasts  

SciTech Connect

As the author states in the Preface, this text attempts to provide a unified approach to chromatography (hence the title) by way of contrasting similarities and differences between gas chromatography (GC), column liquid chromatography (LC), and thin-layer chromatography (TLC). This book is also said to be pitched at an elementary level, suitable for most newcomers to the field (e.g., advanced undergraduates and beginning graduate students in the academic world, as well as bench-level chemists in industry).

Miller, J.M.

1988-01-01

246

Coplanar Waveguide Radial Line Stub  

NASA Technical Reports Server (NTRS)

A coplanar waveguide radial line stub resonator is experimentally characterized with respect to stub radius, sectoral angle, substrate thickness, and relative dielectric constant. A simple closed-form design equation which predicts the resonance radius of the stub is presented.

Simons, R. N.; Taub, S. R.

1993-01-01

247

High Performance Liquid Chromatography  

E-print Network

HPLC - 1 High Performance Liquid Chromatography HPLC MEASUREMENT OF POLYCYCLIC AROMATIC HYDROCARBONS IN CIGARETTE SMOKE Last updated: June 17, 2014 #12;HPLC - 2 High Performance Liquid Chromatography identify as many PAH as possible in cigarette smoke using high performance liquid chromatography (HPLC

Nizkorodov, Sergey

248

Gas Chromatography -Mass Spectrometry  

E-print Network

GCMS - 1 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS OF ETHANOL AND BENZENE IN GASOLINE Last updated: June 17, 2014 #12;GCMS - 2 Gas Chromatography - Mass Spectrometry GC-MS ANALYSIS). The goal of this experiment is to separate the components in a sample of gasoline using Gas Chromatography

Nizkorodov, Sergey

249

Asymmetric Flow Field Flow Fractionation of Aqueous C60 Nanoparticles with Size Determination by Dynamic Light Scattering and Quantification by Liquid Chromatography Atmospheric Pressure Photo-Ionization Mass Spectrometry  

EPA Science Inventory

A size separation method was developed for aqueous C60 fullerene aggregates (aqu/C60) using asymmetric flow field flow fractionation (AF4) coupled to a dynamic light scattering detector in flow through mode. Surfactants, which are commonly used in AF4, were avoided as they may al...

250

Radial distribution of thujaplicins in old growth and second growth western red cedar ( Thuja plicata Donn)  

Microsoft Academic Search

Radial distribution of thujaplicins in western red cedar (Thuja plicata Donn) trees of varying ages was studied in order to assess relative decay resistance of their wood. Samples were extracted with ethanol: benzene (1: 2), and the extractives were analyzed for thujaplicin codtent by a new method utilizing capillary gas chromatography of their methylated derivatives. The combined concentration of thujic

J. Nault

1988-01-01

251

Optimal sizing of capacitors placed on a radial distribution system  

Microsoft Academic Search

The capacitor sizing problem is a special case of the general capacitor placement problem. The problem is to determine the optimal size of capacitors placed on the nodes of a radial distribution system so that the real power losses will be minimized for a given load profile. This problem is formulated as a nonlinear programming problem. The ac power flow

M. E. Baran; F. F. Wu

1989-01-01

252

High power radial klystron oscillator  

SciTech Connect

The advantages of the radial klystron amplifier over the conventional klystron amplifier have been reported by Arman et al. Briefly, the radial structure of this design allows for much smaller impedances and thus higher power, the beam-cavity coupling is stronger because the beam travels inside the cavity, and the source is much more compact because there is no need for external magnetic fields. Here the author reports on possible advantages of the radial klystron oscillator over the radial klystron amplifier. The amplifying nature of certain HPM sources is often mandated by the requirement for synchronization and phase-locking of a number of sources in specific applications. In situations where amplification is solely adhered to for the purpose of achieving higher powers, the oscillator will be a better choice if a mechanism can be found to grow the desired mode at the required frequency. By switching to the oscillator mode there will be no need for priming the cavity or maintaining the phase. This simplifies the design and reduces the operational and maintenance cost of the source. Here he reports that an oscillator version of the radial klystron is possible and in fact more suitable for many applications. The mechanism for exciting and growing the mode will be transit-time effects thus providing all the beneficial features of the transit-time oscillators. The complications due to the presence of thin foils in the radial design still persist and will be dealt with in subsequent works. Numerical simulations using the PIC codes MAGIC and SOS indicate the radial klystron oscillator is a viable and efficient means of rf generation.

Arman, M.J. [Phillips Lab., Kirtland AFB, NM (United States)

1995-11-01

253

Influence of Bonded-Phase Column Type, Mobile Phase Composition, Temperature and Flow-Rate in the Analysis of Triglycerides by Reverse-Phase High Performance Liquid Chromatography  

Microsoft Academic Search

Two chromatographic systems for RP-HPLC analysis of triglycerides, operating under isocratic conditions using octadecylsilane and octylisilane bonded phases, are described.The influence of such chromatographic factors as bonded phase column type, mobile phase composition, temperature and flow rate on retention, analysis selectivity and efficiency, and separation of mixtures of homogeneous triglycerides was assessed. Linear relationships were established for the logarithm of

L. J. R. Barron; G. Santa-María; J. C. Díez Masa

1987-01-01

254

Comprehensive two-dimensional gas chromatography under high outlet pressure conditions: a new approach to correct the flow-mismatch issue in the two dimensions.  

PubMed

The typical column sets employed in comprehensive two-dimensional gas chromatography (GC × GC) suffer from the impossibility to fully exploit the efficiency of both dimensions simultaneously. Adding a restrictor at the end of the second dimension is a possible approach to adjust the linear velocity profile. Under these high outlet pressure conditions the second dimension becomes much slower while the effect on the primary column is limited. The gap in terms of optimum inlet pressures is thus reduced. A program written in Microsoft Excel was used to calculate the efficiencies of the two dimensions in GC × GC at different outlet pressures. A GC × GC set-up with a restrictor at the end of the second dimension column was successfully installed. Experiments proved that this is a possible way to have a better exploitation of the columns. The chromatograms obtained for a number of applications confirm that the separations achieved at elevated outlet pressure are more efficient than those obtained with the same column set under atmospheric outlet conditions. The price to pay is that the separations become considerably slower. PMID:24513348

Peroni, Daniela; Janssen, Hans-Gerd

2014-03-01

255

Effect of rotor meridional velocity ratio on response to inlet radial and circumferential distortion  

NASA Technical Reports Server (NTRS)

Three single transonic fan stages, each having a different meridional velocity ratio across its rotor, were tested with two magnitudes of tip radial distortion and with a 90 deg circumferential distortion imposed on the inlet flow. The rotor with the lowest meridional velocity ratio (less than 0.9 at the tip) demonstrated the least degradation of performance due to these distortions. Loss and deviation angle data (as needed for performance prediction with radial distortion) calculated along actual streamlines for radially distorted flow and correlated against diffusion factor, showed consistent agreement with data calculated along design streamlines for undistorted flow.

Sanger, N. L.

1979-01-01

256

Effect of temperature and flow-rate on analysis of basic compounds in high-performance liquid chromatography using a reversed-phase column  

Microsoft Academic Search

The peak shape and retention of some basic probes together with a neutral reference compound were investigated as a function of temperature and flow-rate using a reversed-phase HPLC column at both pH 3.0 and pH 7.0. The retention of bases often showed an anomalous increase with temperature; retention mechanisms are complex as shown by studies of the effect of buffer

David V. McCalley

2000-01-01

257

Simultaneous amperometric determination of some mono-, di-, and oligosaccharides in flow injection and liquid chromatography using two working enzyme electrodes with different selectivity  

Microsoft Academic Search

A selective dual enzyme electrode system for the monitoring of sugars in flow injection was developed. The working electrodes were based on cellobiose dehydrogenase (CDH) and oligosaccharide dehydrogenase (ODH) ‘wired’ with an osmium-based redox polymer on solid graphite electrodes. In each case the respective enzyme and poly(1-vinylimidazole) (PVI) in which every tenth mer is complexed with osmium (4,4?-dimethylbpy)2Cl, (denoted PVI10dmeOs)

Merid Tessema; Ted Larsson; Torbjörn Buttler; Elisabeth Csöregi; Tautgirdas Ruzgas; Magnus Nordling; Sten-Eric Lindquist; Göran Pettersson; Lo Gorton

1997-01-01

258

A radio-high-performance liquid chromatography dual-flow cell gamma-detection system for on-line radiochemical purity and labeling efficiency determination.  

PubMed

In this study, a method of determining radiochemical yield and radiochemical purity using radio-HPLC detection employing a dual-flow-cell system is evaluated. The dual-flow cell, consisting of a reference cell and an analytical cell, was constructed from two PEEK capillary coils to fit into the well of a NaI(Tl) detector. The radio-HPLC flow was directed from the injector to the reference cell allowing on-line detection of the total injected sample activity prior to entering the HPLC column. The radioactivity eluted from the column was then detected in the analytical cell. In this way, the sample will act as its own standard, a feature enabling on-line quantification of the processed radioactivity passing through the system. All data were acquired on-line via an analog signal from a rate meter using chromatographic software. The radiochemical yield and recovery could be simply and accurately determined by integration of the peak areas in the chromatogram obtained from the reference and analytical cells using an experimentally determined volume factor to correct for the effect of different cell volumes. PMID:24630054

Lindegren, S; Jensen, H; Jacobsson, L

2014-04-11

259

Axial and radial water transport and internal water storage in tropical forest canopy trees  

Microsoft Academic Search

Heat and stable isotope tracers were used to study axial and radial water transport in relation to sapwood anatomical characteristics and internal water storage in four canopy tree species of a seasonally dry tropical forest in Panama. Anatomical characteristics of the wood and radial profiles of sap flow were measured at the base, upper trunk, and crown of a single

Shelley A. James; Frederick C. Meinzer; Guillermo Goldstein; David Woodruff; Timothy Jones; Teresa Restom; Monica Mejia; Michael Clearwater; Paula Campanello

2003-01-01

260

Fracture of the radial head.  

PubMed

The patient was a 22-year-old man who was currently serving in a military special operations training program. He was referred to a physical therapist for a chief complaint of left elbow pain that currently prevented him from performing routine upper extremity exercise activities. Due to the traumatic nature of the patient's injury, inability to fully extend his elbow, and palpation findings, there was concern for a radial head fracture. Therefore, the physical therapist ordered radiographs of the left elbow, which revealed an intra-articular fracture involving the radial head that extended through the neck of the radius. PMID:24787327

McGowen, Jared M; Su, Jonathan; Koppenhaver, Shane L

2014-05-01

261

Chromatography resin support  

DOEpatents

An apparatus and method of using an improved chromatography resin support is disclosed. The chromatography support platform is provided by a stainless steel hollow cylinder adapted for being inserted into a chromatography column. An exterior wall of the stainless steel cylinder defines a groove for carrying therein an "O"-ring. The upper surface of the stainless steel column is covered by a fine stainless steel mesh welded to the edges of the stainless steel cylinder. When placed upon a receiving ledge defined within a chromatography column, the "O"-ring provides a fluid tight seal with the inner edge wall of the chromatography cylinder. The stainless steel mesh supports the chromatography matrix and provides a back flushable support which is economical and simple to construct.

Dobos, James G. (North Augusta, SC)

2002-01-01

262

Simultaneous detection of multi-allergens in an incurred food matrix using ELISA, multiplex flow cytometry and liquid chromatography mass spectrometry (LC-MS).  

PubMed

Food allergy is a public health concern and an important food safety issue. Food allergies affect up to 6% of infants and children and 4% of adults. The objective of this work was to determine differences in the detection of single and multiple allergens (i.e., casein, soy protein, and gluten) in an incurred food matrix before and after baking. Cookies were used as a model food system. Three methods, namely, multiplex assay (a new optimized method based on flow cytometry for multiple allergen analysis), enzyme-linked immunosorbent assay (ELISA) using commercial kits and LC-MS were used to detect allergens in the samples before and after baking. The ELISA kits performed well in detecting allergens in the raw samples with recoveries of 91-108%, 88-127% and 85-108% for casein, soy protein and gluten, respectively. Recoveries were poor for the baked cookies (67-90%, 66-95% and 66-88% for casein, soy protein and gluten, respectively). The multiplex flow cytometry assay permitted multiple allergen detection in the raw samples, with the following recoveries based on soluble protein: casein, 95-107%; soy protein, 92-97%, and gluten, 96-99%. Data for the baked cookies were as follows: casein, 84-90%; soy protein, 80-88%, and gluten, 80-90%. The LC-MS technique detected marker peptides that could be used to identify allergens in the baked food samples up to concentrations of 10ppm for casein and soy protein, and 100ppm for gluten. To the best of our knowledge, the current study is the first to compare ELISA, LC-MS and multiplex flow cytometry methods for the detection of multiple allergens simultaneously incurred in a model food system. PMID:25577123

Gomaa, Ahmed; Boye, Joyce

2015-05-15

263

Simultaneous Quantification of ?9-Tetrahydrocannabinol, 11-nor-9-carboxy-Tetrahydrocannabinol, Cannabidiol and Cannabinol in Oral Fluid by MicroFlow-Liquid Chromatography-High Resolution Mass Spectrometry  

PubMed Central

?9-tetrahydrocannabinol (THC) is the primary target in oral fluid (OF) for detecting cannabis intake. However, additional biomarkers are needed to solve interpretation issues, such as the possibility of passive inhalation by identifying 11-nor-9-carboxy-THC (THCCOOH), and determining recent cannabis smoking by identifying cannabidiol (CBD) and/or cannabinol (CBN). We developed and comprehensively validated a microflow liquid chromatography (LC)–high resolution mass spectrometry method for simultaneous quantification of THC, THCCOOH, CBD and CBN in OF collected with the Oral-Eze® and Quantisal™ devices. One mL OF-buffer solution (0.25mL OF and 0.5mL of Oral-Eze buffer,1:3 dilution, or 0.75mL Quantisal buffer, 1:4 dilution) had proteins precipitated, and the supernatant subjected to CEREX™ Polycrom™ THC solid-phase extraction (SPE). Microflow LC reverse-phase separation was achieved with a gradient mobile phase of 10mM ammonium acetate pH 6 and acetonitrile over 10 min. We employed a Q Exactive high resolution mass spectrometer, with compounds identified and quantified by targeted-MSMS experiments. The assay was linear 0.5–50 ng/mL for THC, CBD and CBN, and 15–500 pg/mL for THCCOOH. Intra- and inter-day and total imprecision were <10.8%CV and bias 86.5–104.9%. Extraction efficiency was 52.4–109.2%, process efficiency 12.2– 88.9% and matrix effect ranged from ?86 to ?6.9%. All analytes were stable for 24h at 5°C on the autosampler. The method was applied to authentic OF specimens collected with Quantisal and Oral-Eze devices. This method provides a rapid simultaneous quantification of THCCOOH and THC, CBD, CBN, with good selectivity and sensitivity, providing the opportunity to improve interpretation of cannabinoid OF results by eliminating the possibility of passive inhalation and providing markers of recent cannabis smoking. PMID:23726246

Concheiro, Marta; Lee, Dayong; Lendoiro, Elena; Huestis, Marilyn A.

2014-01-01

264

A new method for determining delta13C and deltaD simultaneously for CH4 by gas chromatography/continuous-flow isotope-ratio mass spectrometry.  

PubMed

A continuous-flow technique has been developed to analyse the deltaD and delta(13)C values for CH(4) from gas samples, in a single run. This is achieved by splitting the sample gas stream and directing the streams simultaneously through a CuNiPt combustion reactor and an alumina pyrolysis reactor. The CO(2) from CH(4) combustion is trapped in a liquid nitrogen trap while the H(2) exiting the pyrolysis reactor is directed to the mass spectrometer for deltaD(CH4) determination. The CO(2) is then sublimed and directed to the mass spectrometer for delta(13)C(CH4) determination. Sample runs take approximately 10 minutes. This technique gives accurate delta(13)C(CH4) results to within +/-0.3-0.5 per thousand and deltaD(CH4) results to within +/-2-5 per thousand. Injection volumes between 0.5 and 2.5 microL of CH(4), equivalent to between 20 and 100 nmol CH(4), are required for accurate delta(13)C and deltaD analyses, respectively, using sample injection into a split flow with a split ratio of 10. This method provides rapid, accurate and reproducible results on multiple sample runs and is, therefore, an ideal method for analysing natural gas samples from a variety of sources. PMID:14745766

Potter, Joanna; Siemann, Michael G

2004-01-01

265

Cavity Ring-Down Spectroscopy as a Detector for Liquid Chromatography  

E-print Network

Cavity Ring-Down Spectroscopy as a Detector for Liquid Chromatography Kate L. Snyder and Richard N chromatography (HPLC). For this use, we have designed and implemented a Brewster's angle flow cell UV-vis absorption detector for the same path length. High performance liquid chromatography (HPLC

Zare, Richard N.

266

Asymptotic screened hydrogenic radial integrals  

NASA Technical Reports Server (NTRS)

The usefulness of the screened hydrogenic model for the transitions of the helium sequence is studied. The screened hydrogenic radial dipole integral for discrete-discrete transitions from the initial state to the final state is asymptotically expanded to the lowest order such that the final quantum number n approaches infinity. The analytical expression obtained is in terms of confluent hypergeometric functions.

Olsgaard, D. A.; Khan, F.; Khandelwal, G. S.

1988-01-01

267

Molecular size and mass distributions of native starches using complementary separation methods: Asymmetrical Flow Field Flow Fractionation (A4F) and Hydrodynamic and Size Exclusion Chromatography (HDC-SEC)  

Microsoft Academic Search

Starch consists of a mixture of two ?-glucans built mainly upon ?-(1,4) linkages: amylose, an essentially linear polymer,\\u000a and amylopectin, a branched polymer containing 5–6% of ?-(1,6) linkages. The aim of the present work was to analyze the structural\\u000a properties of native starches displaying different amylose-to-amylopectin ratios and arising from different botanical sources,\\u000a using asymmetrical flow field flow fractionation (A4F)

Agnès Rolland-Sabaté; Sophie Guilois; Benoît Jaillais; Paul Colonna

2011-01-01

268

Effects of tip clearance of nozzle vanes on performance of radial turbine rotor  

Microsoft Academic Search

In radial turbines with variable nozzles, the flow downstream of the nozzles could be distorted by the leakage flow through the tip-clearance of the upstream nozzle vanes. To investigate the effects of flow distortion on the performance of turbine rotors, two rotors with different number of blades were tested for three types of distorted velocity distributions at the rotor inlet.

H. Hayami; M. Yamaguchi; Y. Senoo; Y. I. Hyun

1989-01-01

269

Evaluation of interactions between metal ions and nonionic surfactants in high-concentration HCl using low-pressure high-performance liquid chromatography with low-flow-resistance polystyrene-based monolithic column.  

PubMed

A method for evaluating the interactions between metal ions and nonionic surfactants in aqueous solutions containing high-concentration HCl, using gas pressure-driven low-pressure high-performance liquid chromatography (LP-HPLC) as a highly acid-resistant HPLC system, was developed. To construct the LP-HPLC for this purpose, poly(styrene-co-divinylbenzene)-based low-flow-resistance monolithic columns tolerant to highly acidic conditions were prepared using low-conversion thermal polymerization. Thermal polymerization at 65 °C for 1.5 h (monomer conversions, 33% for styrene and 59% for divinylbenzene) allowed preparation of a column with both high separation efficiency (around 60,000 plates m(-1) for alkylbenzenes) and a quite low back pressure of 0.14 MPa at a linear flow rate of 1 mm s(-1) (2.8 × 10(-13) m(2) in permeability). The base column prepared under the above conditions was coated with a nonionic surfactant, polyoxyethylene nonylphenyl ether (PONPE, average oxyethylene unit numbers (n) = 3, 7.5, 15, and 20), and used for evaluation of the interactions between PONPEs and metal ions in 6 M HCl. The interactions between PONPEs and Au(III), Ga(III), Fe(III), Zn(II), and Cu(II) were successfully evaluated using both breakthrough and chromatographic methods. Furthermore, a study of the effect of the polyoxyethylene (POE) chain length revealed that the use of PONPE with the longer POE moiety enhanced the magnitude of the interaction together with the increase in the amount of oxyethylene (OE) units coated on the monolith. Moreover, the interactions of metal ions with a single OE unit were almost constant in the range of n = 7.5-20, whereas the suppression of the interaction between Au(III) with the shortest PONPE chain (n = 3) was also observed. PMID:23884474

Hirano, Tomohiko; Kitagawa, Shinya; Ohtani, Hajime; Kinoshita, Takehiko; Ishigaki, Yuzo; Shibata, Nobuyuki; Nii, Susumu

2013-10-01

270

Electroanalysis of sulfonamides by flow injection system/high-performance liquid chromatography coupled with amperometric detection using boron-doped diamond electrode.  

PubMed

Sulfonamides (SAs) were electrochemically investigated using cyclic voltammetry at a boron-doped diamond (BDD) electrode. Comparison experiments were carried out using a glassy carbon electrode. The BDD electrode provided well-resolved oxidation, irreversible cyclic voltammograms and higher current signals when compared to the glassy carbon electrode. Results obtained from using the BDD electrode in a flow injection system coupled with amperometric detection were illustrated. The optimum potential from a hydrodynamic voltammogram was found to be 1100mV versus Ag/AgCl, which was chosen for the HPLC-amperometric system. Excellent results of linear range and detection limit were obtained. This method was also used for determination of sulfonamides in egg samples. The standard solutions of 5, 10, and 15ppm were spiked in a real sample, and percentage of recoveries was found to be between 90.0 and 107.7. PMID:18970521

Preechaworapun, Anchana; Chuanuwatanakul, Suchada; Einaga, Yasuaki; Grudpan, Kate; Motomizu, Shoji; Chailapakul, Orawon

2006-02-28

271

Separation and quantification of 238U, 232Th and rare earths in monazite samples by ion chromatography coupled with on-line flow scintillation detector.  

PubMed

An alternative procedure has been described for efficient separation and quantitative determination of uranium (U), thorium (Th) and rare earth elements (REEs) in monazite mineral by high performance ion chromatographic system (IC). Different variables affecting the distribution coefficient, the retention and hence separation efficiency such as eluent flow rate and concentrations of HCI and ammonium sulfate (NH4)2SO4 containing the mobile phase were studied. The developed separation protocol of U, Th and REEs was optimized using an Ion Pac CS5 separation column followed by post-column derivatization reaction with Arsenaso III and UV-VIS spectrophotometric detection. Comparative evaluation of U, Th and REEs concentration in monazite mineral was demonstrated using two different on-line detection modes including flow through cell scintillation detector (FSD) and UV-VIS spectrophotometer. Response of the FSD was found to be linear over the full range of activities investigated (4-100 Bq). The lower limits of detection (LLD) for the investigated radionuclides were 3.0+0.1 Bq for 238U and 6.0 +/- 0.1 Bq for 232Th. The detection of 238U and 232Th by FSD shows good agreement with the corresponding determination by UV-VIS spectrophotometer. The content of ThO2 and U3O8 in monazite sample were found to be 4.7 +/- 0.1% and 0.42 +/- 0.04% using UV-VIS detector and 4.3 +/- 0.1% and 0.45 +/- 0.1% using FSD, respectively. PMID:12361323

Borai, E H; Mady, A S

2002-10-01

272

Dynamics of a Radial Electrorheological Clutch  

NASA Astrophysics Data System (ADS)

Time dependent solutions to the equations of motion for flow in an enclosed radial electro-rheological clutch are developed and discussed in relation to the speed of operation. The method follows a procedure previously developed for cylindrical clutch geometry but in this case analytical solutions are obtained. The fluid is treated as a homogeneous continuum obeying the Bingham plastic constitutive equation incorporating a yield stress and viscous component. The results show that the acceleration expected from a consideration of yield stress and inertia is not always achieved. The viscous component places fluid dynamic restriction on the maximum acceleration of the output rotor. However, this limit is only approached if the output load inertia is very low. The results have a bearing on the choice of fluid for high speed operation.

Whittle, M.; Atkin, R. J.; Bullough, W. A.

273

Journal of Chromatography B, 902 (2012) 7883 Contents lists available at SciVerse ScienceDirect  

E-print Network

Journal of Chromatography B, 902 (2012) 78­83 Contents lists available at SciVerse ScienceDirect Journal of Chromatography B journal homepage: www.elsevier.com/locate/chromb Diffusion Split-Flow Thin

Utah, University of

274

CHROMATOGRAPHY B: BIOMEDICAL APPLICATIONS  

E-print Network

JOURNAL OF CHROMATOGRAPHY B: BIOMEDICAL APPLICATIONS ELSEVIER Journal of Chromatography B, 653 Republic blnstitute of Forensic Medicine, University of Verona, Verona, Italy (First received October 8th on the analysis of drugs in animal 0378~4347/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved SSDZ 0378

Miksik, Ivan

275

CHROMATOGRAPHY 6: BIOMEDICAL APPLICATIONS  

E-print Network

JOURNAL OF CHROMATOGRAPHY 6: BIOMEDICAL APPLICATIONS ELSEVIER Journal of Chromatography B, 656 Republic bInstitute of Forensic Medicine, University of Verona, Policlinico Borgo Roma, 37134 Verona, Italy, etc. The start was slow, partly because 0378-4347/94/$07.00 0 1994 Elsevier Science B.V. All rights

Miksik, Ivan

276

Ion Exchange Chromatography  

NSDL National Science Digital Library

This website contains an ion chromatography simulator that can be run online or can be downloaded. The simulator focuses on separations of proteins using Ion Chromatography. Also included is linked reference information, an example of a homework assignment using the simulator, and some information on protein structures.

2011-05-23

277

Column Liquid Chromatography.  

ERIC Educational Resources Information Center

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

Majors, Ronald E.; And Others

1984-01-01

278

Chromatography Theory and Modes  

NSDL National Science Digital Library

This site is an introductory lecture in outline form about chromatography. It appears directed toward biochemical separations. The coverage is broad but not deep. Discussions of counter-current separations, gel permeation, and ion exchange are accompanied by some mention of partition, paper, and gas chromatography. Useful illustrations are also included.

279

Advanced proteomic liquid chromatography  

SciTech Connect

Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput.

Xie, Fang; Smith, Richard D.; Shen, Yufeng

2012-10-26

280

The radial-azimuthal stability of accretion disks - Gas pressure contributions  

NASA Technical Reports Server (NTRS)

A radial-azimuthal stability analysis of a thin, alpha disk accretion flow is presented. The proportion of radiation pressure, Pr, of the unperturbed flow is allowed to vary according to the parameter beta = Pr/P, where P is the total pressure. As is the case for a purely radial analysis, the disk is stable for beta equal to or less than 0.6. However, the coupling of radial and azimuthal perturbations eliminates the viscous instability for such nonradial modes for all values of beta. The group velocity of the retrograde thermal mode is calculated as a function of beta.

Mckee, M. R.

1991-01-01

281

A model of a radially expanding and contracting lymphangion  

PubMed Central

The lymphatic system is an extensive vascular network featuring valves and contractile walls that pump interstitial fluid and plasma proteins back to the main circulation. Immune function also relies on the lymphatic system’s ability to transport white blood cells. Failure to drain and pump this excess fluid results in edema characterized by fluid retention and swelling of limbs. It is, therefore, important to understand the mechanisms of fluid transport and pumping of lymphatic vessels. Unfortunately, there are very few studies in this area, most of which assume Poiseuille flow conditions. In vivo observations reveal that these vessels contract strongly, with diameter changes of the order of magnitude of the diameter itself over a cycle that lasts typically 2–3 seconds. The radial velocity of the contracting vessel is on the order of the axial fluid velocity, suggesting that modeling flow in these vessels with a Poiseuille model is inappropriate. In this paper, we describe a model of a radially expanding and contracting lymphatic vessel and investigate the validity of assuming Poiseuille flow to estimate wall shear stress, which is presumably important for lymphatic endothelial cell mechanotransduction. Three different wall motions; periodic sinusoidal, skewed sinusoidal and physiologic wall motions, were investigated with steady and unsteady parabolic inlet velocities. Despite high radial velocities resulting from the wall motion, wall shear stress values were within 4% of quasi-static Poiseuille values. Therefore, Poiseuille flow is valid for the estimation of wall shear stress for the majority of the lymphangion contractile cycle. PMID:21377158

Rahbar, Elaheh

2011-01-01

282

Liquid-phase chromatography detector  

DOEpatents

A liquid-phase chromatography detector comprising a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focussing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof.

Voigtman, Edward G. (Gainesville, FL); Winefordner, James D. (Gainesville, FL); Jurgensen, Arthur R. (Gainesville, FL)

1983-01-01

283

Liquid-phase chromatography detector  

DOEpatents

A liquid-phase chromatography detector comprises a flow cell having an inlet tubular conduit for receiving a liquid chromatographic effluent and discharging it as a flowing columnar stream onto a vertically adjustable receiving surface spaced apart from and located vertically below and in close proximity to the discharge end of the tubular conduit; a receiver adapted to receive liquid overflowing from the receiving surface; an exit conduit for continuously removing liquid from the receiver; a light source for focusing fluorescence-producing light pulses on the flowing columnar stream as it passes from the outlet of the conduit to the receiving surface and a fluorescence detector to detect the produced fluorescence; a source of light pulse for producing acoustic waves in the columnar stream as it passes from the conduit outlet to the receiving surface; and a piezoelectric transducer adapted to detect those waves; and a source of bias voltage applied to the inlet tubular conduit and adapted to produce ionization of the liquid flowing through the flow cell so as to produce photocurrents therein and an electrical system to detect and record the photocurrents. This system is useful in separating and detecting individual chemical compounds from mixtures thereof. 5 figs.

Voigtman, E.G.; Winefordner, J.D.; Jurgensen, A.R.

1983-11-08

284

RTOD- RADIAL TURBINE OFF-DESIGN PERFORMANCE ANALYSIS  

NASA Technical Reports Server (NTRS)

The RTOD program was developed to accurately predict radial turbine off-design performance. The radial turbine has been used extensively in automotive turbochargers and aircraft auxiliary power units. It is now being given serious consideration for primary powerplant applications. In applications where the turbine will operate over a wide range of power settings, accurate off-design performance prediction is essential for a successful design. RTOD predictions have already illustrated a potential improvement in off-design performance offered by rotor back-sweep for high-work-factor radial turbines. RTOD can be used to analyze other potential performance enhancing design features. RTOD predicts the performance of a radial turbine (with or without rotor blade sweep) as a function of pressure ratio, speed, and stator setting. The program models the flow with the following: 1) stator viscous and trailing edge losses; 2) a vaneless space loss between the stator and the rotor; and 3) rotor incidence, viscous, trailing-edge, clearance, and disk friction losses. The stator and rotor viscous losses each represent the combined effects of profile, endwall, and secondary flow losses. The stator inlet and exit and the rotor inlet flows are modeled by a mean-line analysis, but a sector analysis is used at the rotor exit. The leakage flow through the clearance gap in a pivoting stator is also considered. User input includes gas properties, turbine geometry, and the stator and rotor viscous losses at a reference performance point. RTOD output includes predicted turbine performance over a specified operating range and any user selected flow parameters. The RTOD program is written in FORTRAN IV for batch execution and has been implemented on an IBM 370 series computer with a central memory requirement of approximately 100K of 8 bit bytes. The RTOD program was developed in 1983.

Glassman, A. J.

1994-01-01

285

Radial Distribution Function (RDF) schematic  

NSDL National Science Digital Library

Schematic of the Radial Distribution Function (RDF). The radial distribution function, also known as RDF, g(r), or the pair correlation function, is a measure to determine the correlation between particles within a system. Specifically, it is a measure of, on average, the probability of finding a particle at a distance of r away from a given reference particle, relative to that for an ideal gas. The general algorithm involves determining how many particles are within a distance of r and r+dr away from a particle. This general theme is depicted in the schematic, where the red particle is our reference particle, and blue particles are those which are within the circular shell, dotted in red.

Iacovella, Christopher R.

2006-09-28

286

Asymptotic screened hydrogenic radial integrals.  

PubMed

The screened hydrogenic radial dipole integral for discrete-discrete transitions from initial state n'l' to final state nl is asymptotically expanded to the lowest order such that the final quantum number n --> infinity. The analytical expression obtained is in terms of confluent hypergeometric functions, and explicit expressions for a few of the specific transitions are derived from them as examples. PMID:11539802

Olsgaard, D A; Khan, F; Khandelwal, G S

1988-12-01

287

Radial stability in stratified stars  

E-print Network

We formulate within a generalized distributional approach the treatment of the stability against radial perturbations for both neutral and charged stratified stars in Newtonian and Einstein's gravity. We obtain from this approach the boundary conditions connecting two any phases within a star and underline its relevance for realistic models of compact stars with phase transitions, owing to the modification of the star's set of eigenmodes with respect to the continuous case.

Pereira, Jonas P

2015-01-01

288

Two unusual, radially pulsating stars  

NASA Astrophysics Data System (ADS)

We present the results of pulsation modelling of two unusual radially pulsating stars pds and bep. The former variable is the first BL Her-type star showing the period doubling effect. The second variable is a member of well-detached eclipsing binary system and the first member of a new class of variable stars that mimic RR Lyrae pulsation, but have unusually small masses.

Smolec, Rados?aw

2014-12-01

289

Astronomical Applications for ``Radial Polarimetry''  

NASA Astrophysics Data System (ADS)

Many objects on the sky exhibit a centrosymmetric polarization pattern, particularly in cases involving single scattering around a central source. Utilizing a novel liquid crystal device (the “theta cell'') that transforms the coordinate system of linear polarization in an image plane from Cartesian to polar, the observation of centrosymmetric polarization patterns can be improved: instead of measuring Stokes Q and U on the sky, one only needs to measure Stokes Q' in the new instrument coordinate system. This reduces the effective exposure time by a factor of two and simplifies the polarization modulator design. According to the manufacturer's specifications and to measurements in the lab, the liquid crystal device can be applied in the visible and NIR wavelength range. Astronomical science cases for a“radial polarimeter'' include exoplanet detection, imaging of circumstellar disks, reflection nebulae and light echos, characterization of planetary atmospheres and diagnostics of the solar K-corona. The first astronomical instrument that utilizes a theta cell for radial polarimetry is the S5T (Small Synoptic Second Solar Spectrum Telescope), which accurately measures scattering polarization signals near the limb of the sun. These observations are crucial for understanding the nature and origin of weak, turbulent magnetic fields in the solar photosphere and elsewhere in the universe. A “radial polarimeter'' observing a slightly defocused point source performs one-shot full linear polarimetry. With a theta cell in a pupil plane, a beam's linear polarization properties (e.g. for calibration purposes) can be fully controlled through pupil masking.

Snik, F.

2011-11-01

290

Numerical modeling of the elution peak profiles of retained solutes in supercritical fluid chromatography  

SciTech Connect

In supercritical fluid chromatography (SFC), the significant expansion of the mobile phase along the column causes the formation of axial and radial gradients of temperature. Due to these gradients, the mobile phase density, its viscosity, its velocity, its diffusion coefficients, etc. are not constant throughout the column. This results in a nonuniform flow velocity distribution, itself causing a loss of column efficiency in certain cases, even at low flow rates, as they do in HPLC. At high flow rates, an important deformation of the elution profiles of the sample components may occur. The model previously used to account satisfactorily for the retention of an unsorbed solute in SFC is applied to the modeling of the elution peak profiles of retained compounds. The numerical solution of the combined heat and mass balance equations provides the temperature and the pressure profiles inside the column and values of the retention time and the band profiles of retained compounds that are in excellent agreement with independent experimental data for large value of mobile phase reduced density. At low reduced densities, the band profiles can strongly depend on the column axial distribution of porosity.

Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Guiochon, Georges A [ORNL

2011-01-01

291

Tachoastrometry: astrometry with radial velocities  

NASA Astrophysics Data System (ADS)

Context. Spectra of composite systems (e.g., spectroscopic binaries) contain spatial information that can be retrieved by measuring the radial velocities (i.e., Doppler shifts) of the components in four observations with the slit rotated by 90 degrees in the sky. Aims: We aim at developing a framework to describe the method and to test its capabilities in a real case. Methods: By using basic concepts of slit spectroscopy we show that the geometry of composite systems can be reliably retrieved by measuring only radial velocity differences taken with different slit angles. The spatial resolution is determined by the precision with which differential radial velocities can be measured. Results: We use the UVES spectrograph at the VLT to observe the known spectroscopic binary star HD 188088 (HIP 97944), which has a maximum expected separation of 23 milli-arcseconds. We measure an astrometric signal in radial velocity of 276 m s-1 , which corresponds to a separation between the two components at the time of the observations of 18 ± 2 milli-arcseconds. The stars were aligned east-west. We describe a simple optical device to simultaneously record pairs of spectra rotated by 180 degrees, thus reducing systematic effects. We compute and provide the function expressing the shift of the centroid of a seeing-limited image in the presence of a narrow slit. Conclusions: The proposed technique is simple to use and our test shows that it is amenable for deriving astrometry with milli-arcsecond accuracy or better, beyond the diffraction limit of the telescope. The technique can be further improved by using simple devices to simultaneously record the spectra with 180 degrees angles. This device together with an optimized data analysis will further reduce the measurement errors. With tachoastrometry, radial velocities and astrometric positions can be measured simultaneously for many double line system binaries in an easy way. The method is not limited to binary stars, but can be applied to any astrophysical configuration in which spectral lines are generated by separate (non-rotational symmetric) regions.

Pasquini, L.; Cortés, C.; Lombardi, M.; Monaco, L.; Leão, I. C.; Delabre, B.

2015-02-01

292

Fluctuating Pressure Environments and Hydrodynamic Radial Force Mitigation for a Two Blade Unshrouded Inducer  

NASA Technical Reports Server (NTRS)

Fluctuating pressure data from water flow testing of an unshrouded two blade inducer revealed a cavitation induced oscillation with the potential to induce a radial load on the turbopump shaft in addition to other more traditionally analyzed radial loads. Subsequent water flow testing of the inducer with a rotating force measurement system confirmed that the cavitation induced oscillation did impart a radial load to the inducer. After quantifying the load in a baseline configuration, two inducer shroud treatments were selected and tested to reduce the cavitation induced load. The first treatment was to increase the tip clearance, and the second was to introduce a circumferential groove near the inducer leading edge. Increasing the clearance resulted in a small decrease in radial load along with some steady performance degradation. The groove greatly reduced the hydrodynamic load with little to no steady performance loss. The groove did however generate some new, relatively high frequency, spatially complex oscillations to the flow environment.

Mulder, Andrew; Skelley, Stephen

2011-01-01

293

Elimination of diastereomer interference to determine Telcagepant (MK-0974) in human plasma using on-line turbulent-flow technology and off-line solid-phase extraction coupled with liquid chromatography/tandem mass spectrometry.  

PubMed

To eliminate the diastereomer interference on Telcagepant (MK-0974) determination during clinical study support, on-line high turbulent-flow liquid chromatography (HTLC) methods, HTLC-A and HTLC-B that covered dynamic range of 0.5-500 nM and 5-5000 nM, respectively, were developed. To meet the requirement of rapid assay transfer among multiple laboratories and analysts, a solid-phase extraction (SPE) assay was derived from the existing HTLC-B assay under the same dynamic range. The on-line HTLC assays were achieved through direct injection of plasma samples, extraction of analyte with a Cohesive C18 column (50 mm x 0.5 mm, 50 microm), followed by HPLC separation on a FluoPhase RP column (100 mm x 2.1 mm, 5 microm) and MS/MS detection. The off-line SPE assay used Waters Oasis HLB microElution plate to extract the analytes from plasma matrix before injecting on a FluoPhase RP column (150 mm x 2.1 mm, 5 microm) for LC-MS/MS analysis. Under both on-line and off-line assay conditions, the diastereomer 1c was chromatographically separated from MK-0974. Cross-validation with the pooled samples demonstrated that both on-line and off-line assays provided comparable data with a difference of < 2.6%. The assays were proved to be specific, accurate and reliable, and have been used to support multiple clinical studies. The pros and cons of on-line and off-line assays with regard to man power involved in sample preparation, total analysis time, carryover, cost efficiency, and the requirement for assay transfer are discussed. PMID:19398218

Xu, Yang; Willson, Kenneth J; Anderson, Melanie D G; Musson, Donald G; Miller-Stein, Cynthia M; Woolf, Eric J

2009-06-01

294

Rapid determination of N-acetyl-4-aminophenol (paracetamol) in urine by tandem mass spectrometry coupled with on-line clean-up by two dimensional turbulent flow/reversed phase liquid chromatography.  

PubMed

N-Acetyl-4-aminophenol (NAAP) is the major urinary metabolite of aniline. The general population is known to be ubiquitously exposed to aniline through various sources. Furthermore, NAAP, known under the trade name paracetamol (resp. acetaminophen), is one of the most commonly used over-the-counter analgesics. Recent studies suggest anti-androgenic properties of NAAP. Although NAAP has been used as a pain reliever over decades and its role in aniline metabolism is well known there is a lack of internal exposure data both in environmental and occupational settings. To determine the internal NAAP exposure of the general population, workers exposed to aniline and users of paracetamol we developed a fast on-line HPLC-MS/MS method with isotope dilution quantification of NAAP after enzymatic hydrolysis of its conjugates in urine. We achieved minimal sample pretreatment through on-line extraction and enrichment of the analyte by turbulent flow chromatography on a Waters Oasis HLB phase followed by back-flush transfer onto the analytical column. The limit of quantification (LOQ) was 0.75 ?g/L. In a pilot study, urine samples of 21 volunteers, not occupationally exposed to aniline, were analyzed for NAAP. NAAP was detected in all samples in a wide concentration range between 8.7 ?g/L and 22100 ?g/L (median 85.7 ?g/L). The highest concentration was measured in a volunteer who took paracetamol one day ago. Half of the volunteers quoted to either never have taken paracetamol or at least not during several weeks before the study. Therefore, other routes of exposure than direct use of paracetamol, like aniline or paracetamol contaminated foodstuff, leading to the NAAP excretions have to be taken into account. PMID:23518644

Modick, Hendrik; Schütze, André; Pälmke, Claudia; Weiss, Tobias; Brüning, Thomas; Koch, Holger M

2013-04-15

295

Basic Liquid Chromatography  

NSDL National Science Digital Library

This online textbook offers a variety of information on high performance liquid chromatography (HPLC). Topics covered include instruments, detectors, theory, column selection, and pH effect. This website also contains links to a glossary, useful links, and manufacturer websites.

Dr. Yuri Kazakevich

296

Radial-Electric-Field Piezoelectric Diaphragm Pumps  

NASA Technical Reports Server (NTRS)

In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.

Bryant, Robert G.; Working, Dennis C.; Mossi, Karla; Castro, Nicholas D.; Mane, Pooma

2009-01-01

297

Advanced proteomic liquid chromatography  

PubMed Central

Liquid chromatography coupled with mass spectrometry is the predominant platform used to analyze proteomics samples consisting of large numbers of proteins and their proteolytic products (e.g., truncated polypeptides) and spanning a wide range of relative concentrations. This review provides an overview of advanced capillary liquid chromatography techniques and methodologies that greatly improve separation resolving power and proteomics analysis coverage, sensitivity, and throughput. PMID:22840822

Xie, Fang; Smith, Richard D.; Shen, Yufeng

2012-01-01

298

Gas chromatography in space  

NASA Technical Reports Server (NTRS)

Gas chromatography has proven to be a very useful analytical technique for in situ analysis of extraterrestrial environments as demonstrated by its successful operation on spacecraft missions to Mars and Venus. The technique is also one of the six scientific instruments aboard the Huygens probe to explore Titan's atmosphere and surface. A review of gas chromatography in previous space missions and some recent developments in the current environment of fiscal constraints and payload size limitations are presented.

Akapo, S. O.; Dimandja, J. M.; Kojiro, D. R.; Valentin, J. R.; Carle, G. C.

1999-01-01

299

Chromatography Nomenclature and Definitions  

NSDL National Science Digital Library

This website gives the International Union of Pure and Applied Chemistry approved definitions in the field of chromatography. It is critical for students to appreciate the importance of using standardized nomenclature and definitions. Sections of the site include general terminology, terms related to the chromatographic system, terms related to the chromatographic process and the theory of chromatography, terms related to detection, ion exchange, liquid-liquid distribution (solvent extraction) and other related subjects.

300

Basic Liquid Chromatography  

NSDL National Science Digital Library

The online textbook, Basic Liquid Chromatography, is provided by Dr. Yuri Kazakevich and Dr. Harold McNair of Seton Hall University. For those needing review or an introduction to the subject, the well designed and easily read document contains a wealth of information. Sections include an introduction, instrumentation, detectors, theory, adsorbents, reversed phase, gel permeation chromatography, column selection, pH effect, and even an online short course.

Kazakevich, Yuri.

1996-01-01

301

Two different configurations of flow field-flow fractionation for size analysis of colloids  

SciTech Connect

Flow field-flow fractionation (F.FFF) is a technique for measuring the size of species in the colloidal range (1 nm to 1 [mu]m) which makes the use of the formation of a molecular or colloidal polarization layer at the surface of a filtering membrane. The species to be analyzed are introduced into a flow of liquid passing through a channel with porous walls (of pore size less than that of the colloids to be analyzed) which allow a certain controlled flow to pass through. The remaining fraction of the flow passes through the system, arraying the colloids to a nonspecific detector. The transit time of the colloids through the channel is found to be a function of their size and the permeation rate through the porous membrane. This chromatographic system can be calibrated by using known colloids, such as standard latex particles or fractionated polymer samples, and then used to determine the size of unknown colloids. Here the authors present results obtained in two different systems, an asymmetric module with a rectangular channel having a single flat membrane and a module based on a hollow ultrafiltration fiber with a radial symmetry. The common feature of the two systems is that there is only one fluid inlet. Measurements are reported for the mean size of various samples of real colloids, such as dextran macromolecules, emulsion paints, and milks, and a comparison is made with measurements using hydrodynamic chromatography (HDC), and photon correlation spectrometry. (PCS).

Granger, J.; Dodds, J. (CNRS-ENSIC, Nancy (France))

1992-10-01

302

High-Speed Electrochemically Modulated Liquid Chromatography  

PubMed Central

The performance advantages of carrying out electrochemically modulated liquid chromatography (EMLC) at elevated temperatures and mobile-phase flow rates are investigated. EMLC has the unique ability to manipulate analyte retention and enhance separation efficiencies through changes in the potential applied to a conductive stationary phase. Operation of high-performance liquid chromatography systems at elevated column temperatures also provides pathways to improve chromatographic performance by enhancing analyte diffusivity and facilitating the use of higher mobile-phase flow rates than conventionally attainable. The results show that performing EMLC separations at elevated temperatures (e.g., 100 °C) reduces the analysis time of a mixture of aromatic sulfonates in a mixed mobile phase by more than a factor of 20. Moreover, use of higher operating temperatures enables the separation of this mixture with an entirely aqueous mobile phase in less than 2 min. PMID:15456303

Ponton, Lisa M.; Porter, Marc D.

2006-01-01

303

Development of a thermal and structural analysis procedure for cooled radial turbines  

Microsoft Academic Search

A procedure for computing the rotor temperature and stress distributions in a cooled radial turbine is considered. Existing codes for modeling the external mainstream flow and the internal cooling flow are used to compute boundary conditions for the heat transfer and stress analyses. An inviscid, quasi three-dimensional code computes the external free stream velocity. The external velocity is then used

Ganesh N. Kumar; Russell G. Deanna

1988-01-01

304

Freeze chromatography method and apparatus  

DOEpatents

A freeze chromatography method and apparatus are provided which enable separation of the solutes contained in a sample. The apparatus includes an annular column construction comprising cylindrical inner and outer surfaces defining an annular passage therebetween. One of the surfaces is heated and the other cooled while passing an eluent through the annular passageway so that the eluent in contact with the cooled surface freezes and forms a frozen eluent layer thereon. A mixture of solutes dissolved in eluent is passed through the annular passageway in contact with the frozen layer so that the sample solutes in the mixture will tend to migrate either toward or away the frozen layer. The rate at which the mixture flows through the annular passageway is controlled so that the distribution of the sample solutes approaches that at equilibrium and thus a separation between the sample solutes occurs. 3 figs.

Scott, C.D.

1987-04-16

305

On the formation of multiple rotating Pelton-like flame structures in radial microchannels with lean methane–air mixtures  

Microsoft Academic Search

This paper reports the experimental observation of multiple Pelton-like rotating flame structures in radial microchannels with lean methane-air mixtures supplied at the center of the two closely placed circular quartz plates. The bottom quartz plate was heated with a porous burner to create a positive temperature gradient distribution along the flow direction. Stable flames were observed at a radial location

Sudarshan Kumar; Kaoru Maruta; S. Minaev

2007-01-01

306

Radial viscous fingers and diffusion-limited aggregation: Fractal dimension and growth sites  

Microsoft Academic Search

We show that fractal viscous fingers can be formed in a Hele-Shaw cell with radial symmetry, thereby permitting their study-for the first time-without the complicating effects of boundary conditions such as those present in the conventional linear cell. We find-for a wide range of shear-thinning fluids, flow rates, and plate separations-that radial viscous fingers have a fractal dimension df=1.70+\\/-0.05, the

Gérard Daccord; Johann Nittmann; H. Eugene Stanley

1986-01-01

307

Ulysses observations of the radial magnetic field  

Microsoft Academic Search

The radial component of the magnetic field in the southern hemisphere has been measured at Ulysses as it traveled from the equator to -80.2° latitude and returned. The radial component multiplied by the square of the radial distance, i.e., BRr2, averaged over 77 day intervals (three solar rotations) is approximately constant at -3.5 nT and shows no evidence of a

Edward J. Smith; A. Balogh

1995-01-01

308

Hollow Cathode With Multiple Radial Orifices  

NASA Technical Reports Server (NTRS)

Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

Brophy, John R.

1992-01-01

309

Effect of radial inflow on vortex intensification for a tornado-type wind turbine  

SciTech Connect

A new wind vortex turbine, called tornado-type wind turbine, was studied both theoretically and experimentally for the purpose of better understanding the basic nature of a vortex flow and further improvement of its power efficiencies. Analytical solutions were obtained from the Navier-Stokes equations for the velocity distributions along the radial distance. The result demonstrates the important nature of a vortex structure that, in order to intensify a vortex inside the tower, radial inflow must be provided from the side walls. Based upon this concept, the essential contribution of our experimental work was to furnish the radial inflow by utilizing the dynamic head of incoming wind.

Hsu, C.T.; Ide, H.

1982-09-01

310

The radial hyperaemic response: a new and objective assessment of ulnar collateral supply to the hand.  

PubMed

The assessment of adequate ulnar collateral supply to the hand is mandatory prior to the harvest of the radial artery as a conduit for coronary artery bypass grafting. However, there is currently no one test which is widely used in all centres. We report a new and objective method of assessing ulnar collateral supply to the hand prior to harvest of the radial artery. This technique involves assessing the presence of a hyperaemic flow response to occlusion of the radial artery using an intraoperative transit time flowmeter. We found this technique to be objective and reliable, and would advocate its use in patients with a positive Allen's test. PMID:11888782

Roberts, N; Ghosh, S; Boehm, M; Galiñanes, M

2002-03-01

311

Fabrication of cooled radial turbine rotor  

NASA Technical Reports Server (NTRS)

A design and fabrication program was conducted to evaluate a unique concept for constructing a cooled, high temperature radial turbine rotor. This concept, called split blade fabrication was developed as an alternative to internal ceramic coring. In this technique, the internal cooling cavity is created without flow dividers or any other detail by a solid (and therefore stronger) ceramic plate which can be more firmly anchored within the casting shell mold than can conventional detailed ceramic cores. Casting is conducted in the conventional manner, except that the finished product, instead of having finished internal cooling passages, is now a split blade. The internal details of the blade are created separately together with a carrier sheet. The inserts are superalloy. Both are produced by essentially the same software such that they are a net fit. The carrier assemblies are loaded into the split blade and the edges sealed by welding. The entire wheel is Hot Isostatic Pressed (HIPed), braze bonding the internal details to the inside of the blades. During this program, two wheels were successfully produced by the split blade fabrication technique.

Hammer, A. N.; Aigret, G. G.; Psichogios, T. P.; Rodgers, C.

1986-01-01

312

High Performance Liquid Chromatography  

NASA Astrophysics Data System (ADS)

High performance liquid chromatography (HPLC) has many applications in food chemistry. Food components that have been analyzed with HPLC include organic acids, vitamins, amino acids, sugars, nitrosamines, certain pesticides, metabolites, fatty acids, aflatoxins, pigments, and certain food additives. Unlike gas chromatography, it is not necessary for the compound being analyzed to be volatile. It is necessary, however, for the compounds to have some solubility in the mobile phase. It is important that the solubilized samples for injection be free from all particulate matter, so centrifugation and filtration are common procedures. Also, solid-phase extraction is used commonly in sample preparation to remove interfering compounds from the sample matrix prior to HPLC analysis.

Talcott, Stephen

313

Momentum balance and radial electric fields in axisymmetric and nonaxisymmetric toroidal plasmas  

NASA Astrophysics Data System (ADS)

We have investigated the influence of symmetry properties of toroidal magnetic configurations on the mechanisms used for determining the radial electric field such as the momentum balance and the ambipolar particle transport. Both neoclassical and anomalous transport of particles, heat and momentum in axisymmetric and nonaxisymmetric toroidal systems are taken into account. Generally, in nonaxisymmetric systems, the radial electric field is determined by the neoclassical ambipolarity condition. For axisymmetric systems with up-down symmetry and quasisymmetric systems with stellarator symmetry, it is shown using a novel parity transformation that the particle fluxes are automatically ambipolar up to {\\cal O}(\\delta^2) and the determination of the radial electric field Es requires solving the {\\cal O}(\\delta^3) momentum balance equations, where ? denotes the ratio of the thermal gyroradius to the characteristic equilibrium scale length. In axisymmetric systems with large E × B flows on the order of the ion thermal velocity vTi, the radial fluxes of particles, heat and toroidal momentum are dependent on Es and its radial derivative while the time evolution of the Es profile is governed by the {\\cal O}(\\delta^2) toroidal momentum balance equation. In nonaxisymmetric systems, E × B flows of {\\cal O}(v_{T{\\rmi}}) are not generally allowed even in the presence of quasisymmetry because the nonzero radial current is produced by the large flow term in the equilibrium force balance for which the Boozer and Hamada coordinates cannot be constructed.

Sugama, H.; Watanabe, T. H.; Nunami, M.; Nishimura, S.

2011-02-01

314

Modern Thin-Layer Chromatography.  

ERIC Educational Resources Information Center

Some of the important modern developments of thin-layer chromatography are introduced. Discussed are the theory and instrumentation of thin-layer chromatography including multidimensional and multimodal techniques. Lists 53 references. (CW)

Poole, Colin F.; Poole, Salwa K.

1989-01-01

315

Performance, resolving power, and radial ion distributions of a prototype nanoelectrospray ionization resistive glass atmospheric pressure ion mobility spectrometer.  

PubMed

In this article, we describe and characterize a novel ion mobility spectrometer constructed with monolithic resistive glass desolvation and drift regions. This instrument is equipped with switchable corona discharge and nanoelectrospray ionization sources and a Faraday plate detector. Following description of the instrument, pulsing electronics, and data acquisition system, we examine the effects of drift gas flow rate and temperature, and of the aperture grid to anode distance on the observed resolving power and sensitivity. Once optimum experimental parameters are identified, different ion gate pulse lengths, and their effect on the temporal spread of the ion packet were investigated. Resolving power ranged from an average value of 50 ms/ms for a 400-micros ion gate pulse, up to an average value of 68 ms/ms for a 100-micros ion gate pulse, and a 26-cm drift tube operated at 383 V cm(-1). Following these experiments, the radial distribution of ions in the drift region of the spectrometer was studied by using anodes of varying sizes, showing that the highest ionic density was located at the center of the drift tube. Finally, we demonstrate the applicability of this instrument to the study of small molecules of environmental relevance by analyzing a commercially available siderophore, deferoxamine mesylate, in both the free ligand and Fe-bound forms. Ion mobility experiments showed a dramatic shift to shorter drift times caused by conformational changes upon metal binding, in agreement with previous reversed-phase liquid chromatography observations. PMID:17854161

Kwasnik, Mark; Fuhrer, Katrin; Gonin, Marc; Barbeau, Katherine; Fernandez, Facundo M

2007-10-15

316

Aerodynamic Evaluation of Two Compact Radial-Inflow Turbine Rotors  

NASA Technical Reports Server (NTRS)

The aerodynamic evaluation of two highly loaded compact radial turbine rotors was conducted at the NASA Lewis Research Center Small Engine Component Test Facility (SECTF). The experimental results were used for proof-of-concept, for modeling radial inflow turbine rotors, and for providing data for code verification. Two rotors were designed to have a shorter axial length, up to a 10-percent reduced diameter, a lighter weight, and equal or higher efficiencies with those of conventional radial inflow turbine rotors. Three configurations were tested: rotor 1, having a 40-percent shorter axial length, with the design stator (stator 1); rotor 1 with the design stator vanes closed down (stator 2); and rotor 2, slightly shorter axially and having higher loading, with stator 2. The stator had 36 vanes and the rotors each had 14 solid blades. Although presently uncooled, the rotor blades were designed for thicknesses which would allow cooling passages to be added. The overall stage performance measurements and the rotor and stator exit flow field surveys were obtained. Measurements of steady state temperatures, pressures, mass flow rates, flow angles, and output power were made at various operating conditions. Data were obtained at corrected speeds of 80, 90, 100, 110, and 120 percent of design over a range of equivalent inlet-to-exit pressure ratios of 3.5, 4.0, 4.5, and 5.0, the maximum pressure ratio achieved. The test showed that the configuration of rotor 1 with stator 1 running at the design pressure ratio produced a flow rate which was 5.6 percent higher than expected. This result indicated the need to close down the stator flow area to reduce the flow. The flow area reduction was accomplished by restaggering the vanes. Rotor 1 was retested with the closed-down stator vanes and achieved the correct mass flow. Rotor 2 was tested only with the restaggered vanes. The test results of the three turbine configurations were nearly identical. Although the measured efficiencies of the compact designs fell 2 to 3 points below the predicted efficiency of 91 percent, they did meet and exceed by up to 2.5 percentage points the efficiences of state-of-the-art turbines found in the literature.

Simonyi, P. Susan; Roelke, Richard J.; Stabe, Roy G.; Nowlin, Brentley C.; Dicicco, Danielle

1995-01-01

317

Cone thin-layer chromatography  

NASA Astrophysics Data System (ADS)

A new variant of chromatography, cone chromatography, is suggested. In this variant, a thin-layer chromatography (TLC) plate on a flexible support (for example, foil) is cone-shaped. This variant is compared with the classic linear and circular variants using chromatographic characteristics (retardation factor R f and efficiency H, ?m) and the time of chromatographing with ethanol as a mobile phase. Cone chromatography is intermediate in the series linear-cone-circular TLC variants.

Berezkin, V. G.; Kormishkina, E. V.

2008-08-01

318

Instrumentation for Liquid Chromatography  

NASA Astrophysics Data System (ADS)

High performance liquid chromatography (HPLC) is one of the most rapidly growing and potentially largest branches of analytical chemistry. Although further advances in HPLC are to be expected, current methodology is already far enough advanced to insure its use in the clinical laboratory.

Henry, Richard A.; Sivorinovsky, Genrikh

319

Inverse Paper Chromatography  

Microsoft Academic Search

Available methods of examination do not provide absolute certainty that two samples of paper have the same origin. A new technique for testing paper, known as inverse paper chromatography (IPC), is based on using a strip of paper as the chromatographic sorbent medium on which a mixture of known probes is separated under standardized conditions. The resulting chromatogram will uniquely

Irving I. Ziderman

1982-01-01

320

Paper Chromatography with Leaves  

NSDL National Science Digital Library

In this activity on page 5 of the PDF, learners use chromatography to separate and identify pigments within various leaves. Learners soak leaf pieces in warmed rubbing alcohol and then dip coffee filter paper in the alcohol, lifting and separating the leaf pigments according to size.

2013-07-08

321

Gas Chromatography Application Notes  

NSDL National Science Digital Library

This site includes application notes on gas chromatography from 2000-2005 which have been presented at conferences. The applications could serve as a source of experiments for advanced teaching labs and may also assist those interested in solving analytical problems that involve separations.

322

Investigating Chromatography: selecting variables  

NSDL National Science Digital Library

This activity is a classroom investigation where students separate pigment in dyes in order to learn about mixtures and solutions. They use chromatography to design and experiment with a single variable to answer a question about which ink will separate the most - has the greatest variety of pigment.

Nancy Gerber

323

Analyze Candy Using Chromatography  

NSDL National Science Digital Library

Learners analyze candy-coated sweets using chromatography. Learners use this method to separate the various dyes used to make colored candy. Learners can try this activity with different types of candy or with candy of different colors and compare the results.

2014-06-24

324

Split Injection Gas Chromatography  

NSDL National Science Digital Library

This animation site deals specifically with split injection in gas chromatography. The animations are short (one to two minutes each) and can easily be shown in class as part of a lecture. They are extremely helpful in illustrating key components and concepts of chromatographic systems. Users are encouraged to explore the site and the other brief animations as well.

325

Gas Chromatography Video  

NSDL National Science Digital Library

This is a high quality video module demonstrating the basics of gas chromatography. Highlights include different GC instruments and detectors as well as unique topics such as trouble shooting and interfacing the column that are not addressed in standard texts. This resource can be run (Shockwave Flash) from the home server or downloaded to your computer.

326

High Performance Thin Layer Chromatography.  

ERIC Educational Resources Information Center

Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

Costanzo, Samuel J.

1984-01-01

327

Chromatography: Who Wrote the Note?  

NSDL National Science Digital Library

This lesson has students solving the mystery of a note by conducting chromatography. They will test different washable markers and see that different marker colors are made up of various pigments. They will compare and contrast the note chromatography with other chromatography results from a variety of markers.

Rebecca Hansing

328

Modern Physics Problem: Radial Wave Functions  

NSDL National Science Digital Library

The two Physlets show a density plot of the Hydrogenic wavefunction and the solution to the radial equation. The word "density" refers to a method for plotting 3-D information on a two dimensional screen. Here it has nothing to do with the probability density in quantum mechanics. The radial solutions used here are the associated Laguerre polynomials scaled with a0 = 1.

Christian, Wolfgang; Belloni, Mario

2007-03-03

329

Design and Numerical Simulation of Radial Inflow Turbine Volute  

NASA Astrophysics Data System (ADS)

The volute of a radial inflow turbine has to be designed to ensure that the desired rotor inlet conditions like absolute Mach number, flow angle etc. are attained. For the reasonable performance of vaneless volute turbine care has to be taken for reduction in losses at an appropriate flow angle at the rotor inlet, in the direction of volute, whose function is to convert gas energy into kinetic energy and direct the flow towards the rotor inlet at an appropriate flow angle with reduced losses. In literature it was found that the incompressible approaches failed to provide free vortex and uniform flow at rotor inlet for compressible flow regimes. So, this paper describes a non-dimensional design procedure for a vaneless turbine volute for compressible flow regime and investigates design parameters, such as the distribution of area ratio and radius ratio as a function of azimuth angle. The nondimensional design is converted in dimensional form for three different volute cross sections. A commercial computational fluid dynamics code is used to develop numerical models of three different volute cross sections. From the numerical models, losses generation in the different volutes are identified and compared. The maximum pressure loss coefficient for Trapezoidal cross section is 0.1075, for Bezier-trapezoidal cross section is 0.0677 and for circular cross section is 0.0438 near tongue region, which suggested that the circular cross section will give a better efficiency than other types of volute cross sections.

Shah, Samip P.; Channiwala, S. A.; Kulshreshtha, D. B.; Chaudhari, Gaurang

2014-12-01

330

AUTO-EXPANSIVE FLOW  

EPA Science Inventory

Physics suggests that the interplay of momentum, continuity, and geometry in outward radial flow must produce density and concomitant pressure reductions. In other words, this flow is intrinsically auto-expansive. It has been proposed that this process is the key to understanding...

331

Combination radial and thrust magnetic bearing  

NASA Technical Reports Server (NTRS)

A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

Blumenstock, Kenneth A. (Inventor)

2002-01-01

332

Numerical modeling of elution peak profiles in supercritical fluid chromatography. Part I-Elution of an unretained tracer  

SciTech Connect

When chromatography is carried out with high-density carbon dioxide as the main component of the mobile phase (a method generally known as 'supercritical fluid chromatography' or SFC), the required pressure gradient along the column is moderate. However, this mobile phase is highly compressible and, under certain experimental conditions, its density may decrease significantly along the column. Such an expansion absorbs heat, cooling the column, which absorbs heat from the outside. The resulting heat transfer causes the formation of axial and radial gradients of temperature that may become large under certain conditions. Due to these gradients, the mobile phase velocity and most physico-chemical parameters of the system (viscosity, diffusion coefficients, etc.) are no longer constant throughout the column, resulting in a loss of column efficiency, even at low flow rates. At high flow rates and in serious cases, systematic variations of the retention factors and the separation factors with increasing flow rates and important deformations of the elution profiles of all sample components may occur. The model previously used to account satisfactorily for the effects of the viscous friction heating of the mobile phase in HPLC is adapted here to account for the expansion cooling of the mobile phase in SFC and is applied to the modeling of the elution peak profiles of an unretained compound in SFC. The numerical solution of the combined heat and mass balance equations provides temperature and pressure profiles inside the column, and values of the retention time and efficiency for elution of this unretained compound that are in excellent agreement with independent experimental data.

Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Guiochon, Georges A [ORNL

2010-01-01

333

Magnetic Resonance Microimaging and Numerical Simulations of Velocity Fields Inside Enlarged Flow Cells Used for Coupled NMR Microseparations  

PubMed Central

The coupling of various chemical microseparation methods with small-scale NMR detection is a growing area in analytical chemistry. The formation of enlarged flow cells within the active volume of the NMR detector can significantly increase the coil filling factor and hence the signal-to-noise ratio of the NMR spectra. However, flow cells can also lead to deterioration of the separation efficiency due to the development of complex flow patterns, the form of which depend on the particular geometry of the flow cell and the flow rate used. In this study, we investigated the flow characteristics in different flow cell geometries relevant to the coupling of capillary liquid chromatography and NMR. Computational fluid dynamics was used to simulate fluid flow inside flow cells with a volume of ~ 1 µL. Magnetic resonance microimaging was used to measure experimentally the velocity fields inside these flow cells. The results showed good agreement between experiment and simulation and demonstrated that a relatively gradual expansion and contraction is necessary to avoid areas of weak recirculation and strong radial velocities, both of which can potentially compromise separation efficiency. PMID:15732916

Zhang, Xiaofeng; Webb, Andrew G.

2009-01-01

334

Improved synchronized accumulating radioisotope detector for gas chromatography.  

PubMed

A synchronized accumulating radioisotope detector for radio gas chromatography was developed. It comprised seven gas-flow proportional counters each with an inner volume of 10 ml. Every counter tube was connected by a mutual anti-coincidence circuit to reduce the background. The transit time of gas particles in one counter tube could be set to an optimal value between 1 and 4 s by regulating the flow-rate of the counting gas, according to analytical requirements. The improved detector maintained high chromatographic resolution, which suggested the applicability of the apparatus to capillary gas chromatography. PMID:2753949

Akira, K; Baba, S

1989-04-14

335

Improved 2D time-of-flight angiography using a radial-line k-space acquisition.  

PubMed

For flow imaging applications, radial-line k-space acquisition methods offer advantages over conventional 2DFT methods. Specifically, radial-line acquisition methods mitigate artifacts resulting from pulsatile flow while offering a potential reduction in scan times. In this paper, radial-line and 2DFT acquisitions are compared in a two-dimensional time-of-flight angiography sequence. The twisting radial-line (TwiRL) trajectory, a variant of 2D projection reconstruction, is used to represent the family of radial-line trajectories. In both phantom and in vivo studies, the TwiRL images demonstrate improved vessel depiction including a more uniform signal intensity and better delineation of the vasculature in comparison with images obtained via the 2DFT method. PMID:9001154

Nielsen, H T; Olcott, E W; Nishimura, D G

1997-02-01

336

Complications related to radial artery occlusion, radial artery harvest, and arterial lines.  

PubMed

Recent publications have suggested that there may be an important role for the radial artery regarding long-term perfusion of the hand. The increasing popularity of the radial artery as an access site for cardiac catheterization has also resulted in the recognition of acute and chronic radial artery occlusion, and cardiologists have placed renewed emphasis on preserving the patency of this artery for future interventional procedures. This article reviews the present literature on radial artery harvest and occlusion. Also discussed are the complications associated with radial artery occlusion and treatment options to prevent such complications. PMID:25455360

Chim, Harvey; Bakri, Karim; Moran, Steven L

2015-02-01

337

Hydrodynamic effects in a misaligned radial face seal  

NASA Technical Reports Server (NTRS)

Hydrodynamic effects in a flat seal having an angular misalignment are analyzed, taking into account the radial variation in seal clearance. An analytical solution for axial force, restoring moment, and transverse moment is presented that covers the whole range from zero to full angular misalignment. Both low pressure seals with cavitating flow and high pressure seals with full fluid film are considered. Strong coupling is demonstrated between angular misalignment and transverse moment which leads the misalignment vector by 90 degrees. This transverse moment, which is entirely due to hydrodynamic effects, is a significant factor in the seal operating mechanism.

Etsion, I.

1977-01-01

338

Cooling characteristics of air cooled radial turbine blades  

NASA Astrophysics Data System (ADS)

The cooling design and the cooling characteristics of air cooled radial turbine wheels, which are designed for use with the gas generator turbine for the 400 horse power truck gas turbine engine, are presented. A high temperature and high speed test was performed under aerodynamically similar conditions to that of the prototype engine in order to confirm the metal temperature of the newly developed integrated casting wheels constructed of the superalloys INCO 713C. The test results compared with the analytical value, which was established on the basis of the results of the heat transfer test and the water flow test, are discussed.

Sato, T.; Takeishi, K.; Matsuura, M.; Miyauchi, J.

339

Chromatography Can Separate!  

NSDL National Science Digital Library

In this chemistry activity, learners use thin layer chromatography to determine the molecular composition of different markers. First, they use pure rubbing alcohol as the liquid phase, then experiment with mixtures of alcohol and water to see which works best. Different black markers can be tried to see how their components compare. A quantitative measure of the "retention factor" is calculated to relate the distance traveled by the spot to the distance traveled by the mobile phase. A later experiment has learners try to identify an unknown ink sample by comparing it to known samples, and then opens it up to artistic pattern-making using chromatography and markers. The activity is written to be part of a kit, but the kit is not required.

2012-05-14

340

Ion Pairing Chromatography  

Microsoft Academic Search

The present state of ion-pair chromatography (IPC) is reviewed. Emphasis is placed on the theoretical modeling of the retention behavior of charged, zwitterionic, and neutral solutes, since the theory provides the generally good understanding of the factors affecting the separation. Although stoichiometric models were credited with the first easy-to-understand demonstration of the retention mechanism of IPC, they were thermodynamic models,

Teresa Cecchi

2008-01-01

341

Multilayer analytic element modeling of radial collector wells.  

PubMed

A new multilayer approach is presented for the modeling of ground water flow to radial collector wells. The approach allows for the inclusion of all aspects of the unique boundary condition along the lateral arms of a collector well, including skin effect and internal friction losses due to flow in the arms. The hydraulic conductivity may differ between horizontal layers within the aquifer, and vertical anisotropy can be taken into account. The approach is based on the multilayer analytic element method, such that regional flow and local three-dimensional detail may be simulated simultaneously and accurately within one regional model. Horizontal flow inside a layer is computed analytically, while vertical flow is approximated with a standard finite-difference scheme. Results obtained with the proposed approach compare well to results obtained with three-dimensional analytic element solutions for flow in unconfined aquifers. The presented approach may be applied to predict the yield of a collector well in a regional setting and to compute the origin and residence time, and thus the quality, of water pumped by the collector well. As an example, the addition of three lateral arms to a collector well that already has three laterals is investigated. The new arms are added at an elevation of 2 m above the existing laterals. The yield increase of the collector well is computed as a function of the lengths of the three new arms. PMID:16324013

Bakker, Mark; Kelson, Victor A; Luther, Kenneth H

2005-01-01

342

Performance of vaned radial diffusers  

E-print Network

diagram at the trailing edge station for high flow rate 71 NOMENCLATURZ A ? area of pipe 1 A ? area of orifice 2 AR ? exit-to-throat area ratio C ? discharge coefficient C ? coefficient of pressure p D ? diameter of pipe 1 D ? diameter of orifice... down the diffuser channel until, finally, there is no significant effect at the trailing edge. The shroud-to-hub yaw angle distributions at the two inlet stations are fairly symmetric about the channel centerline with the average value being...

Piemsomboon, Pornchai

2012-06-07

343

Rotating stall control in a high-speed stage with inlet distortion. Part 1: Radial distortion  

SciTech Connect

This paper presents the first attempt to stabilize rotating stall in a single-stage transonic axial flow compressor with inlet distortion using active feedback control. The experiments were conducted at the NASA Lewis Research Center on a single-stage transonic core compressor inlet stage. An annular array of 12 jet-injectors located upstream of the rotor tip was used for forced response testing and to extend the compressor stable operating range. Results for radial distortion are reported in this paper. First, the effects of radial distortion on the compressor performance and the dynamic behavior were investigated. Control laws were designed using empirical transfer function estimates determined from forced response results. The transfer function indicated that the compressor dynamics are decoupled with radial inlet distortion, as they are for the case of undistorted inlet flow. Single-input-single-output (SISO) control strategies were therefore used for the radial distortion controller designs. Steady axisymmetric injection of 4 percent of the compressor mass flow resulted in a reduction in stalling mass flow of 9.7 percent relative to the case with inlet distortion and no injection. Use of a robust H{sub {infinity}} controller with unsteady nonaxisymmetric injection achieved a further reduction in stalling mass flow of 7.5 percent, resulting in a total reduction of 17.2 percent.

Spakovszky, Z.S.; Weigl, H.J.; Paduano, J.D. [Massachusetts Inst. of Technology, Cambridge, MA (United States). Gas Turbine Lab.; Schalkwyk, C.M. van [Scientific Systems Co., Woburn, MA (United States); Suder, K.L.; Bright, M.M. [NASA Lewis Research Center, Cleveland, OH (United States)

1999-07-01

344

Classification of volcanoes of the Kane Patera Quadrangle of Io: Proportions of lava flows and pyroclastic flows  

NASA Technical Reports Server (NTRS)

Voyager 1 images show 14 volcanic centers wholly or partly within the Kane Patera quadrangle of Io, which are divided into four major classes: (1) shield with parallel flows; (2) shield with early radial fan shapd flows; (3) shield with radial fan shaped flows, surfaces of flows textured with longitudinal ridges; and (4) depression surrounded by plateau-forming scarp-bounded, untextured deposits. The interpretation attempted here hinges largely on the ability to distinguish lava flows from pyroclastic flows by remote sensing.

Elston, W. E.

1984-01-01

345

Radial Velocity Fluctuations of RZ Psc  

NASA Astrophysics Data System (ADS)

The behavior of the radial velocity of the UX Ori type star RZ Psc is studied. The existence of an inner cavity with a radius of about 0.7 a.u. in the circumstellar disk of this star allows to suggest the presence of a companion. A study of the radial velocity of RZ Psc based on our own measurements and published data yields no periodic component in its variability. The two most accurate measurements of V r , based on high resolution spectra obtained over a period of three months, show that the radial velocity is constant over this time interval to within 0.5 km/s. This imposes a limit of M p ?10 M Jup on the mass of the hypothetical companion. Possible reasons for the observed strong fluctuations in the radial velocity of this star are discussed.

Potravnov, I. S.; Gorynya, N. A.; Grinin, V. P.; Minikulov, N. Kh.

2014-12-01

346

An unusual cause of radial nerve palsy.  

PubMed

Neurapraxia frequently occurs following traction injury to the nerve intraoperatively, leading to radial nerve palsy which usually recovers in 5-30 weeks. In our case, we had operated a distal one-third of humeral shaft fracture and fixed it with 4.5 mm limited contact dynamic compression plate. The distal neurovascular status of the limb was assessed postoperatively in the recovery room and was found to be intact and all the sensory-motor functions of the radial nerve were normal. On the second postoperative day, following the suction drain removal and dressing, patient developed immediate radial nerve palsy along with wrist drop. We reviewed the literature and found no obvious cause for the nerve palsy and concluded that it was due to traction injury to the radial nerve while removing the suction drain in negative pressure. PMID:24889983

Agrawal, Hemendra Kumar; Khatkar, Vipin; Garg, Mohit; Singh, Balvinder; Jaiman, Ashish; Sharma, Vinod Kumar

2014-06-01

347

Radial construction of an arterial wall.  

PubMed

Some of the most serious diseases involve altered size and structure of the arterial wall. Elucidating how arterial walls are built could aid understanding of these diseases, but little is known about how concentric layers of muscle cells and the outer adventitial layer are assembled and patterned around endothelial tubes. Using histochemical, clonal, and genetic analysis in mice, here we show that the pulmonary artery wall is constructed radially, from the inside out, by two separate but coordinated processes. One is sequential induction of successive cell layers from surrounding mesenchyme. The other is controlled invasion of outer layers by inner layer cells through developmentally regulated cell reorientation and radial migration. We propose that a radial signal gradient controls these processes and provide evidence that PDGF-B and at least one other signal contribute. Modulation of such radial signaling pathways may underlie vessel-specific differences and pathological changes in arterial wall size and structure. PMID:22975322

Greif, Daniel M; Kumar, Maya; Lighthouse, Janet K; Hum, Justine; An, Andrew; Ding, Ling; Red-Horse, Kristy; Espinoza, F Hernan; Olson, Lorin; Offermanns, Stefan; Krasnow, Mark A

2012-09-11

348

Genetics Home Reference: Duane-radial ray syndrome  

MedlinePLUS

... literature OMIM Genetic disorder catalog Conditions > Duane-radial ray syndrome On this page: Description Genetic changes Inheritance ... definitions Reviewed December 2009 What is Duane-radial ray syndrome? Duane-radial ray syndrome is a disorder ...

349

Mechanical properties of radial truck tires  

E-print Network

MECHANICAL PROPERTIES OF RADIAL TRUCK TIRES A Thesis by MANSOOR-UL-HASSAN WASTI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1992... Major Subject: Mechanical Engineering MECHANICAL PROPERTIES OF RADIAL TRUCK TIRES A Thesis by Mansoor-ul-Hassan Wasti Approved as to style and content by: R. . Alexander (Chair of Committee) C. . Hough (Member) Donal ayl (M mber) W. L. radley...

Wasti, Mansoor-ul-Hassan

1992-01-01

350

Radial averages of astigmatic TEM images.  

PubMed

The Contrast Transfer Function (CTF) of an image, which modulates images taken from a Transmission Electron Microscope (TEM), is usually determined from the radial average of the power spectrum of the image (Frank, J., Three-dimensional Electron Microscopy of Macromolecular Assemblies, Oxford University Press, Oxford, 2006). The CTF is primarily defined by the defocus. If the defocus estimate is accurate enough then it is possible to demodulate the image, which is popularly known as the CTF correction. However, it is known that the radial average is somewhat attenuated if the image is astigmatic (see Fernando, K.V., Fuller, S.D., 2007. Determination of astigmatism in TEM images. Journal of Structural Biology 157, 189-200) but this distortion due to astigmatism has not been fully studied or understood up to now. We have discovered the exact mathematical relationship between the radial averages of TEM images with and without astigmatism. This relationship is determined by a zeroth order Bessel function of the first kind and hence we can exactly quantify this distortion in the radial averages of signal and power spectra of astigmatic images. The argument to this Bessel function is similar to an aberration function (without the spherical aberration term) except that the defocus parameter is replaced by the differences of the defoci in the major and minor axes of astigmatism. The ill effects due this Bessel function are twofold. Since the zeroth order Bessel function is a decaying oscillatory function, it introduces additional zeros to the radial average and it also attenuates the CTF signal in the radial averages. Using our analysis, it is possible to simulate the effects of astigmatism in radial averages by imposing Bessel functions on idealized radial averages of images which are not astigmatic. We validate our theory using astigmatic TEM images. PMID:18662790

Fernando, K Vince

2008-10-01

351

Efficiency in supercritical fluid chromatography with different superficially porous and fully porous particles ODS bonded phases.  

PubMed

The chromatographic efficiency, in terms of plate number per second, was dramatically improved by the introduction of sub-two microns particles with ultra-high pressure liquid chromatography (UHPLC). On the other hand, the recent development of superficially porous particles, called core-shell or fused-core particles, appears to allow the achievement of the same efficiency performances at higher speed without high pressure drops. CO?-based mobile phases exhibiting much lower viscosities than aqueous based mobile phases allow better theoretical efficiencies, even with 3-5 ?m particles, but with relative low pressure drops. They also allow much higher flow rates or much longer columns while using conventional instruments capable to operate below 400 bar. Moreover, the use of superficially porous particles in SFC could enhance the chromatographic performances even more. The kinetic behavior of ODS phases bonded on these particles was studied, with varied flow rates, outlet (and obviously inlet) pressures, temperatures, by using a homologous series (alkylbenzenes) with 10% modifier (methanol or acetonitrile) in the carbon dioxide mobile phase. Results were also compared with classical fully porous particles, having different sizes, from 2.5 to 5 ?m. Superior efficiency (N) and reduced h were obtained with these new ODS-bonded particles in regards to classical ones, showing their great interest for use in SFC. However, surprising behavior were noticed, i.e. the increase of the theoretical plate number vs. the increase of the chain length of the compounds. This behavior, opposite to the one classically reported vs. the retention factor, was not depending on the outlet pressure, but on the flow rate and the temperature changes. The lower radial trans-column diffusion on this particle types could explain these results. This diffusion reduction with these ODS-bonded superficially porous particles seems to decrease with the increase of the residence time of compounds. PMID:22192562

Lesellier, E

2012-03-01

352

Anomalous radial transport in tokamak edge plasma  

NASA Astrophysics Data System (ADS)

Energy from nuclear fusion of Hydrogen isotopes is a possible alternative to fossil fuels. For this to be of practical utility, confinement of Hydrogen in a plasma state for a minimum duration is necessary. Since confinement is strongly affected by radial transport processes, understanding the observed modes of radial transport in confined plasma is of vital importance for progress towards fusion energy. The present dissertation is aimed at studying radial(cross-field) transport in the tokamak edge plasma. The present thesis is divided into three parts: (1) In the first part, we present a model of generation of intermittent convective meso-scale structures (blobs) based on the synergy of the interchange drive and nonlinear effects associated with drift--wave turbulence. (2) In the second part, we attempt to explain the preferential propagation of blobs radially outward as a consequence of the radially decreasing density of a confined plasma. (3) In the third part, we present a model for simulating anomalous radial transport in kinetic codes for tokamak edge plasma.

Bodi, Vasudeva Raghavendra Kowsik

353

Radial pulsations in DB white dwarfs?  

NASA Technical Reports Server (NTRS)

Theoretical models of DB white dwarfs are unstable against radial pulsation at effective temperatures near 20,000-30,000 K. Many high-overtone modes are unstable, with periods ranging from 12 s down to the acoustic cutoff period of approximately 0.1 s. The blue edge for radial instability lies at slightly higher effective temperatures than for nonradial pulsations, with the temperature of the blue edge dependent on the assumed efficiency of convection. Models with increased convective efficiency have radial blue edges that are increasingly closer to the nonradial blue edge; in all models the instability persists into the nonradial instability strip. Radial pulsations therefore may exist in the hottest DB stars that lie below the DB gap; the greatest chance for detection would be observations in the ultraviolet. These models also explain why searches for radial pulsations in DA white dwarfs have failed: the efficient convection needed to explain the blue edge for nonradial DA pulsation means that the radial instability strip is 1000 K cooler than found in previous investigations. The multiperiodic nature of the expected pulsations can be used to advantage to identify very low amplitude modes using the uniform spacing of the modes in frequency. This frequency spacing is a direct indicator of the mass of the star.

Kawaler, Steven D.

1993-01-01

354

Cooled High-temperature Radial Turbine Program 2  

NASA Technical Reports Server (NTRS)

The objective of this program was the design and fabrication of a air-cooled high-temperature radial turbine (HTRT) intended for experimental evaluation in a warm turbine test facility at the LeRC. The rotor and vane were designed to be tested as a scaled version (rotor diameter of 14.4 inches diameter) of a 8.021 inch diameter rotor designed to be capable of operating with a rotor inlet temperature (RIT) of 2300 F, a nominal mass flow of 4.56 lbm/sec, a work level of equal or greater than 187 Btu/lbm, and efficiency of 86 percent or greater. The rotor was also evaluated to determine it's feasibility to operate at 2500 F RIT. The rotor design conformed to the rotor blade flow path specified by NASA for compatibility with their test equipment. Fabrication was accomplished on three rotors, a bladeless rotor, a solid rotor, and an air-cooled rotor.

Snyder, Philip H.

1991-01-01

355

Experimental evaluation of a translating nozzle sidewall radial turbine  

NASA Technical Reports Server (NTRS)

Studies have shown that reduced specific fuel consumption of rotorcraft engines can be achieved with a variable capacity engine. A key component in such an engine in a high-work, high-temperature variable geometry gas generator turbine. An optimization study indicated that a radial turbine with a translating nozzle sidewall could produce high efficiency over a wide range of engine flows but substantiating data were not available. An experimental program with Teledyne CAE, Toledo, Ohio was undertaken to evaluate the moving sidewall concept. A variety of translating nozzle sidewall turbine configurations were evaluated. The effects of nozzle leakage and coolant flows were also investigated. Testing was done in warm air (121 C). The results of the contractual program were summarized.

Roelke, Richard J.; Rogo, Casimir

1987-01-01

356

Variable area radial turbine fabrication and test program  

NASA Technical Reports Server (NTRS)

A variable area radial turbine with a moveable nozzle sidewall was experimentally evaluated. The turbine was designed for an advanced variable capacity gas turbine rotorcraft engine. The turbine has a mass flow rate of 2.27 kg/sec (5.0 lbs/sec), and a rotor inlet temperature of 1477K (2200 F). Testing was conducted at a reduced inlet temperature, but the aerodynamic parameters and Reynolds numbers were duplicated. Overall performance was obtained for a range of nozzle areas from 50% to 100% of the maximum area. The test program determined the effect on performance of: (1) Moving the hub or shroud sidewall; (2) Sidewall-vane clearance leakage; (3) Vaneless space geometry change; and (4) Nozzle cooling flows. Data were obtained for a range of pressure ratios and speeds and are presented in a number of performance maps.

Rogo, C.

1986-01-01

357

Computer program for design analysis of radial-inflow turbines  

NASA Technical Reports Server (NTRS)

A computer program written in FORTRAN that may be used for the design analysis of radial-inflow turbines was documented. The following information is included: loss model (estimation of losses), the analysis equations, a description of the input and output data, the FORTRAN program listing and list of variables, and sample cases. The input design requirements include the power, mass flow rate, inlet temperature and pressure, and rotational speed. The program output data includes various diameters, efficiencies, temperatures, pressures, velocities, and flow angles for the appropriate calculation stations. The design variables include the stator-exit angle, rotor radius ratios, and rotor-exit tangential velocity distribution. The losses are determined by an internal loss model.

Glassman, A. J.

1976-01-01

358

Fluctuating Pressure Environments and Hydrodynamic Radial Force Mitigation for a Two Blade Unshrouded Inducer  

NASA Technical Reports Server (NTRS)

Fluctuating pressure data from water flow testing of an unshrouded two blade inducer revealed a cavitation induced oscillation with the potential to induce a radial load on the turbopump shaft in addition to other more traditionally analyzed radial loads. Subsequent water flow testing of the inducer with a rotating force measurement system confirmed that the cavitation induced oscillation did impart a radial load to the inducer. After quantifying the load in a baseline configuration, two inducer shroud treatments were selected and tested to reduce the cavitation induced load. The first treatment was to increase the tip clearance, and the second was to introduce a circumferential groove near the inducer leading edge. Increasing the clearance resulted in a small load decrease along with some steady performance degradation. The groove greatly reduced the hydrodynamic load with little to no steady performance loss. The groove did however generate some new, relatively high frequency, spatially complex oscillations to the environment.

Mulder, Andrew; Skelley, Stephen

2011-01-01

359

A Better Method for Filling Pasteur Pipet Chromatography Columns  

ERIC Educational Resources Information Center

An alternative method for the preparation of Pasteur pipet chromatography columns is presented that allows the column to be filled with solvent without bubbles and allows greater control of fluid flow while the materials to be separated are added. Students are required to wear gloves and goggles and caution should be used while handling glass…

Ruekberg, Ben

2006-01-01

360

HPLC- High Performance Liquid Chromatography  

NSDL National Science Digital Library

This primer on High Performance Liquid Chromatography (HCLC) gives a brief history and definition of liquid chromatography (LC), LC techniques, and defines both HPLC and UltraPerformance Liquid Chromatography (UPLC Technology). The other chapters of the primer are available on the left side of the page: How Does High Performance Liquid Chromatography Work?, Identifying and Quantitating Compounds, HPLC Column Hardware, and HPLC Separation Modes. An appendix which defines HPLC nomenclature is also available. Each section is pepper with helpful and clear illustrations to help users visualize the processes and procedures presented.

361

Separating with Chromatography  

NSDL National Science Digital Library

In this experiment, learners separate different types of molecules in marker inks (using a technique called "thin layer chromatography"). Learners mark dots at the bottom of a strip of paper (stationary phase) and put the paper into a cup of water (liquid mobile phase) to see how the inks separate. The experiment is repeated with more colors, then mixtures of colors. The final investigation is to figure out who took a cookie, by analyzing the ink used to write a note left in the cookie jar, and comparing the ink to markers taken from two suspects. The activity is written as part of a kit, but can be done without the kit.

Maisie Shaw

2010-01-01

362

Gas Chromatography Experiment  

NSDL National Science Digital Library

This Microsoft Word document describes a Gas Chromatography experiment involving the separation and quantitation of four butyl alcohol isomers. It has a complete background about the components of a GC instrument (with labeled pictures) and their functions. The exercise includes a section devoted to the measurement of response factors of the detector in use (here an FID). This would be a good experiment for a new faculty member to use as is, with slight modification to make it relevant to the particular GC system to be used.

363

Thin Layer Chromatography  

NSDL National Science Digital Library

Developed by the University of Southern Maine for college level chemistry students, this website offers instructive modules dealing with topics related to thin layer chromatography. Using Macromedia Shockwave, these interactive modules incorporate questions within the informative materials to advance users in their problem solving abilities. Topics covered at the website include RF Factor, hydrogen binding, visualization, and stationary phase. With the extensive use of diagrams and figures and the inclusion of a helpful glossary, students seeking assistance in chemistry can learn a great deal at this educational web site.

364

Numerical solution of Navier-Stokes equations using multiquadric radial basis function networks  

Microsoft Academic Search

A numerical method based on radial basis function networks (RBFNs) for solving steady incompressible viscous flow problems (including Boussinesq materials) is presented in this paper. The method uses a universal approximator based on neural network methodology to represent the solutions. The method is easy to implement and does not require any kind of finite element-type discretization of the domain and

Nam Mai-Duy; Thanh Tran-Cong

2001-01-01

365

Regime diagrams and characteristics of flame patterns in radial microchannels with temperature gradients  

Microsoft Academic Search

Comprehensive regime diagrams of flame pattern formation in radial microchannels with temperature gradients were drawn based on experimental findings. A premixed methane–air mixture was introduced at the center of microchannels formed by two parallel circular quartz plates that were heated with an external porous burner to create a positive temperature gradient condition in the direction of flow. Combustion behavior in

Aiwu Fan; Sergey Minaev; Sudarshan Kumar; Wei Liu; Kaoru Maruta

2008-01-01

366

Comminuted fractures of the radial head  

PubMed Central

Background There have been few reports on the long-term outcome of comminuted radial head fractures in adults. Method 10 women and 9 men with a mean age of 45 (21–65) years when they sustained a comminuted fracture of the radial head were re-evaluated after 15–25 years. 6 patients had been nonoperatively (NO) treated while 13 had had a radial head excision. The uninjured elbow served as a control. Results At follow-up, 11 patients (4 NO patients) rated their fractured elbow as being without deficits, 7 (1 NO) as being slightly impaired, and 1 (NO) as being severely impaired. Range of motion and elbow strength were not impaired, and even though there were more degenerative changes such as cysts, osteophytes, and sclerosis in the injured elbows by radiography, the prevalence of joint space reduction was not higher. Interpretation Most patients with an isolated comminuted fracture of the radial head treated nonoperatively or with a radial head excision report no or only minor long-term complaints. PMID:20367419

Herbertsson, Pär; Nordqvist, Anders; Besjakov, Jack; Josefsson, Per Olof; Hasserius, Ralph

2010-01-01

367

Radial interchange motions of plasma filaments  

SciTech Connect

Radial convection of isolated filamentary structures due to interchange motions in magnetized plasmas is investigated. Following a basic discussion of vorticity generation, ballooning, and the role of sheaths, a two-field interchange model is studied by means of numerical simulations on a biperiodic domain perpendicular to the magnetic field. It is demonstrated that a blob-like plasma structure develops dipolar vorticity and electrostatic potential fields, resulting in rapid radial acceleration and formation of a steep front and a trailing wake. While the dynamical evolution strongly depends on the amount of collisional diffusion and viscosity, the structure travels a radial distance many times its initial size in all parameter regimes in the absence of sheath dissipation. In the ideal limit, there is an inertial scaling for the maximum radial velocity of isolated filaments. This velocity scales as the acoustic speed times the square root of the structure size relative to the length scale of the magnetic field. The plasma filament eventually decelerates due to mixing and collisional dissipation. Finally, the role of sheath dissipation is investigated. When included in the simulations, it significantly reduces the radial velocity of isolated filaments. The results are discussed in the context of convective transport in scrape-off layer plasmas, comprising both blob-like structures in low confinement modes and edge localized mode filaments in unstable high confinement regimes.

Garcia, O. E.; Bian, N. H.; Fundamenski, W. [Association EURATOM-Risoe National Laboratory, P.O. Box 49, OPL-128 Risoe, DK-4000 Roskilde (Denmark); School of Physics and Astronomy, University of Manchester, Manchester M60 1QD (United Kingdom); EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

2006-08-15

368

Radial spoke proteins of Chlamydomonas flagella  

PubMed Central

Summary The radial spoke is a ubiquitous component of ‘9+2’ cilia and flagella, and plays an essential role in the control of dynein arm activity by relaying signals from the central pair of microtubules to the arms. The Chlamydomonas reinhardtii radial spoke contains at least 23 proteins, only 8 of which have been characterized at the molecular level. Here, we use mass spectrometry to identify 10 additional radial spoke proteins. Many of the newly identified proteins in the spoke stalk are predicted to contain domains associated with signal transduction, including Ca2+-, AKAP- and nucleotide-binding domains. This suggests that the spoke stalk is both a scaffold for signaling molecules and itself a transducer of signals. Moreover, in addition to the recently described HSP40 family member, a second spoke stalk protein is predicted to be a molecular chaperone, implying that there is a sophisticated mechanism for the assembly of this large complex. Among the 18 spoke proteins identified to date, at least 12 have apparent homologs in humans, indicating that the radial spoke has been conserved throughout evolution. The human genes encoding these proteins are candidates for causing primary ciliary dyskinesia, a severe inherited disease involving missing or defective axonemal structures, including the radial spokes. PMID:16507594

Yang, Pinfen; Diener, Dennis R.; Yang, Chun; Kohno, Takahiro; Pazour, Gregory J.; Dienes, Jennifer M.; Agrin, Nathan S.; King, Stephen M.; Sale, Winfield S.; Kamiya, Ritsu; Rosenbaum, Joel L.; Witman, George B.

2007-01-01

369

A design of coaxial-to-radial line adaptors in radial line slot antennas  

Microsoft Academic Search

A numerical design of a coaxial-to-radial line adaptor is presented for the use as a feed in a radial line slot antenna. To realize stable performances in mass production, the reflection from a probe type adaptor in which only the outer conductor of a coaxial line is in contact with the waveguide, is analyzed and suppressed. The tolerance for the

Makoto Natori; Makoto Ando; Naohisa Goto

1990-01-01

370

DNA migration regimes in hydrodynamic chromatography and slalom chromatography: evidence for a transition.  

PubMed

Recently, we hypothesized that DNA separation mechanisms in slalom chromatography (SC) and packed column hydrodynamic chromatography (HDC) could be connected and simultaneously observed 'J. Chromatogr. A 886 (2000) 1'. The present paper describes the migration of various circular and linear double-stranded DNAs in a chromatographic system using a C1 stationary phase and an acetonitrile-phosphate buffer mixture as a mobile phase. The migration dependence on the flow rate for the different species showed the relative contribution of both the SC and HDC separation mechanisms. A transition between the SC and HDC regimes was demonstrated for the first time. In addition, the data were analyzed in terms of polymer migration in a dense structure. Three different behaviors were distinguished in relation to the size and the compactness of the nucleic acid. PMID:18968372

Peyrin, E; Caron, C; Garrel, C; Ravel, A; Villet, A; Grosset, C; Favier, A

2001-08-30

371

OFF-DESIGN PERFORMANCE OF RADIAL INFLOW TURBINES  

NASA Technical Reports Server (NTRS)

This program calculates off design performance of radial inflow turbines. The program uses a one dimensional solution of flow conditions through the turbine along the main streamline. The loss model accounts for stator, rotor, incidence, and exit losses. Program features include consideration of stator and rotor trailing edge blockage and computation of performance to limiting load. Stator loss (loss in kinetic energy across the stator) is proportional to the average kinetic energy in the blade row and is represented in the program by an equation which includes a stator loss coefficient determined from design point performance and then assumed to be constant for the off design calculations. Minimum incidence loss does not occur at zero incidence angle with respect to the rotor blade, but at some optimum flow angle. At high pressure ratios the level of rotor inlet velocity seemed to have an excessive influence on the loss. Using the component of velocity in the direction of the optimum flow angle gave better correlations with experimental results. Overall turbine geometry and design point values of efficiency, pressure ratio, and mass flow are needed as input information. The output includes performance and velocity diagram parameters for any number of given speeds over a range of turbine pressure ratio. The program has been implemented on the IBM 7094 and operates in batch mode.

Wasserbauer, C. A.

1994-01-01

372

Generalized Radially Self-Accelerating Helicon Beams  

NASA Astrophysics Data System (ADS)

We report, in theory and experiment, on a new class of optical beams that are radially self-accelerating and nondiffracting. These beams continuously evolve on spiraling trajectories while maintaining their amplitude and phase distribution in their rotating rest frame. We provide a detailed insight into the theoretical origin and characteristics of radial self-acceleration and prove our findings experimentally. As radially self-accelerating beams are nonparaxial and a solution to the full scalar Helmholtz equation, they can be implemented in many linear wave systems beyond optics, from acoustic and elastic waves to surface waves in fluids and soft matter. Our work generalized the study of classical helicon beams to a complete set of solutions for rotating complex fields.

Vetter, Christian; Eichelkraut, Toni; Ornigotti, Marco; Szameit, Alexander

2014-10-01

373

Dispersion-free radial transmission lines  

DOEpatents

A dispersion-free radial transmission line ("DFRTL") preferably for linear accelerators, having two plane conductors each with a central hole, and an electromagnetically permeable material ("EPM") between the two conductors and surrounding a channel connecting the two holes. At least one of the material parameters of relative magnetic permeability, relative dielectric permittivity, and axial width of the EPM is varied as a function of radius, so that the characteristic impedance of the DFRTL is held substantially constant, and pulse transmission therethrough is substantially dispersion-free. Preferably, the EPM is divided into concentric radial sections, with the varied material parameters held constant in each respective section but stepwise varied between sections as a step function of the radius. The radial widths of the concentric sections are selected so that pulse traversal time across each section is the same, and the varied material parameters of the concentric sections are selected to minimize traversal error.

Caporaso, George J. (Livermore, CA); Nelson, Scott D. (Patterson, CA)

2011-04-12

374

Radial force balance within Jupiter's dayside magnetosphere  

NASA Astrophysics Data System (ADS)

A local field stress technique, developed previously in a study of the Saturnian magnetosphere, is introduced to the problem of determining the radial force balance characteristics of Jupiter's magnetosphere. The authors begin by estimating the near-equatorial, radial magnetic force densities using the data obtained by Voyager 1 principally on the dayside (inbound) portion of its trajectory (7.4 ? R(Rj) ? 42). Using the low-energy charged particle data (?30 keV) and other published data they then explore ways in which the field forces might be balanced. Comparing present results with the results of a previous study, the authors note that contrary to common expectations, Saturn rather than Jupiter is unique in having the corotation centrifugal forces dominate over other sources of radial particle force in some regions of the middle (ring current) equatorial magnetosphere.

Mauk, B. H.; Krimigis, S. M.

1987-09-01

375

Manufacturing of Precision Forgings by Radial Forging  

SciTech Connect

Radial forging is a multi purpose incremental forging process using four tools on the same plane. It is widely used for the forming of tool steels, super alloys as well as titanium- and refractory metals. The range of application goes from reducing the diameters of shafts, tubes, stepped shafts and axels, as well as for creating internal profiles for tubes in Near-Net-Shape and Net-Shape quality. Based on actual development of a weight optimized transmission input shaft, the specific features of radial forging technology is demonstrated. Also a Finite Element Model for the simulation of the process is shown which leads to reduced pre-processing effort and reduced computing time compared to other published simulation methods for radial forging. The finite element model can be applied to quantify the effects of different forging strategies.

Wallner, S.; Harrer, O.; Buchmayr, B. [Chair of Metal Forming, Department Product Engineering, University of Leoben, Franz Josef Strasse 18, 8700 Leoben (Austria); Hofer, F. [GFM GmbH, Ennser Strasse 14, 4403 Steyr (Austria)

2011-01-17

376

Temperature gradient interaction chromatography of polymers: A molecular statistical model.  

PubMed

A new model describing the retention in temperature gradient interaction chromatography of polymers is developed. The model predicts that polymers might elute in temperature gradient interaction chromatography in either an increasing or decreasing order or even nearly independent of molar mass, depending on the rate of the temperature increase relative to the flow rate. This is in contrast to solvent gradient elution, where polymers elute either in order of increasing molar mass or molar mass independent. The predictions of the newly developed model were verified with the literature data as well as new experimental data. PMID:20960449

Radke, Wolfgang; Lee, Sekyung; Chang, Taihyun

2010-11-01

377

Multiplex gas chromatography  

NASA Technical Reports Server (NTRS)

The principles of the multiplex gas chromatography (GC) technique, which is a possible candidate for chemical analysis of planetary atmospheres, are discussed. Particular attention is given to the chemical modulators developed by present investigators for multiplex GC, namely, the thermal-desorption, thermal-decomposition, and catalytic modulators, as well as to mechanical modulators. The basic technique of multiplex GC using chemical modulators and a mechanical modulator is demonstrated. It is shown that, with the chemical modulators, only one gas stream consisting of the carrier in combination with the components is being analyzed, resulting in a simplified instrument that requires relatively few consumables. The mechanical modulator demonstrated a direct application of multiplex GC for the analysis of gases in atmosphere of Titan at very low pressures.

Valentin, Jose R.

1990-01-01

378

Masson's Hemangioma of Proximal Radial Artery.  

PubMed

Tumour like vascular lesions are rare. Here we report a rare case of tumor like vascular lesion from the radial artery. A pulsatile swelling in the forearm is usually diagnosed as a case of Aneurysm, AV fistula or highly vascular tumor. A middle aged man came to us with a painless pulsatile swelling on the lateral aspect of proximal right forearm. The ultrasound scan reported it as case of vascular tumour. Angiogram showed abnormal vascular channels, connected to the aneurysmal dialation of the proximal radial artery. Histopthological examination confirmed it as Masson's hemangioma after excision. This is a benign condition and complete excision is curative. PMID:24799774

Pinjala, Ramakrishna

2014-02-01

379

Talbot interferometer for radial and lateral derivatives.  

PubMed

The theory and experimental evidence of a shearing interferometer based on the Talbot effect are presented. Multiple-shearing interferences are obtained that can be reduced to triple-shearing or doubleshearing interferences by the addition of simple spatial filtering. When the shear is less than the width of the details in the object, these interferences become either the second or first derivative of the object under test, respectively. Either lateral or constant radial shear can be introduced by choosing Ronchi rulings or circular gratings. Thus both lateral and radial derivatives are easily obtained. If white light is used as a source, color fringes of high contrast are observed. PMID:20119380

Silva, D E

1972-11-01

380

Magnetic Bearing With Radial and Angular Control  

NASA Technical Reports Server (NTRS)

Active magnetic bearing stably levitates rotor against radial (lateral) and axial motion and points rotor axis in controllable direction, yet allows rotor to turn freely about own axis. Rotor only moving part, and absence of mechanical contact between rotor and stator assures long life. Active magnetic bearing includes electromagnet coils tilting rotor clockwise or counterclockwise, or move it right or left. Feedback control system maintains rotor at equilibrium radial and angular positions in response to signals from position sensors. No active control needed to maintain equilibrium axial position. Adjustable magnetic bearing useful in high-speed rotating devices, robotic joints, and supports for optical elements.

Studer, P. A.

1987-01-01

381

Aircraft radial-belted tire evaluation  

NASA Technical Reports Server (NTRS)

An overview is given of the ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program being conducted at NASA Langley's Aircraft Landing Dynamics Facility (ALDF). The START Program involves tests using three different tire sizes to evaluate tire rolling resistance, braking, and cornering performance throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Preliminary results from recent 40 x 14 size bias-ply, radial-belted, and H-type aircraft tire tests are discussed. The paper concludes with a summary of the current program status and planned ALDF test schedule.

Yager, Thomas J.; Stubbs, Sandy M.; Davis, Pamela A.

1990-01-01

382

Accordion Phenomenon in the Radial Artery  

PubMed Central

The accordion phenomenon is a well-known finding mechanism in the field of interventional cardiology. It is a benign condition and has mainly been described in tortuous coronary arteries during percutaneous coronary interventions. It is believed to be induced by a stiff guidewire. However, this phenomenon has not been observed previously in the radial artery. We present a case of accordion phenomenon in the radial artery, which was successfully resolved after the catheters and the wire were retrieved, with the pseudolesions found to have completely disappeared in subsequent image findings. PMID:24516747

Dahdouh, Ziad S.; Abdel-Massih, Tony; Sarkis, Antoine; Grollier, Gilles

2014-01-01

383

Investigation on centrifugal impeller in an axial-radial combined compressor with inlet distortion  

NASA Astrophysics Data System (ADS)

Assembling an axial rotor and a stator at centrifugal compressor upstream to build an axial-radial combined compressor could achieve high pressure ratio and efficiency by appropriate size augment. Then upstream potential flow and wake effect appear at centrifugal impeller inlet. In this paper, the axial-radial compressor is unsteadily simulated by three-dimensional Reynolds averaged Navier-Stokes equations with uniform and circumferential distorted total pressure inlet condition to investigate upstream effect on radial rotor. The results show that span-wise nonuniform total pressure distribution is generated and radial and circumferential combined distortion is formed at centrifugal rotor inlet. The upstream stator wake deflects to rotor rotation direction and decreases with blade span increases. Circumferential distortion causes different separated flow formations at different pitch positions. The tip leakage vortex is suppressed in centrifugal blade passages. Under distorted inlet condition, flow direction of centrifugal impeller leading edge upstream varies evidently near hub and shroud but varies slightly at mid-span. In addition, compressor stage inlet distortion produces remarkable effect on blade loading of centrifugal blade both along chordwise and pitchwise.

Li, Du; Yang, Ce; Zhao, Ben; Zhou, Mi; Qi, Mingxu; Zhang, Jizhong

2011-12-01

384

The Stationary Condensation and Radial Outflow of a Liquid Film on a Horizontal Disk  

NASA Technical Reports Server (NTRS)

The application of capillary screen liquid acquisition devices to space-based cryogenic propulsion systems is expected to necessitate thermodynamic conditioning in order to stabilize surface tension retention characteristics. The present results have been obtained in the framework of the research of low gravity condensation-flow processes for conditioning cryogenic liquid acquisition devices. The following system is studied: On the top of a subcooled horizontal disk, a liquid film condenses from the ambient saturated vapor. The liquid is forcedly removed at the disk edge, and there is an outward radial flow of the film. Stationary regimes of the flow are uncovered such that (i) the gravity is negligible, being eclipsed by the capillary forces; (ii) the film thickness is everywhere much smaller than the disk radius; and (iii) the slow-flow lubrication approximation is valid. A nonlinear differential equation for the film thickness as a function of the radial coordinate is obtained. The (two-dimensional) fields of velocities, temperature and pressure in the film are explicitly determined by the radial profile of its thickness. The equilibrium is controlled by two parameters: (i) the vapor-disk difference of temperatures and (ii) the liquid exhaust rate. For the flow regimes with a nearly uniform film thickness, the governing equation linearizes, and the film interface is analytically predicted to have a concave-up quartic parabola profile. Thus, perhaps counter-intuitively, the liquid film is thicker at the edge and thinner at the center of the disk.

Bolshinskiy, Leonid; Frenkel, Alexander

2008-01-01

385

Radial recession osteotomy for early Kienböck's disease  

Microsoft Academic Search

Between 1995 and 1999, ten patients with Lichtman stage II and III Kienböck's disease with negative ulnar variance underwent a joint-levelling radial recession osteotomy in our unit. The procedure was performed by the senior author in all cases. Eight patients were available for follow-up (average 31 months). Based on the Mayo Clinic modification of the Green wrist score, there were

A. J. Laing; B. Lenehan; T. Oh; M. O'Sullivan

2002-01-01

386

Optimal capacitor placement on radial distribution systems  

Microsoft Academic Search

Capacitor placement problem on radial distribution systems is formulated and a solution algorithm is proposed. The location, type, and size of capacitors, voltage constraints, and load variations are considered in the problem. The objective of capacitor placement is peak power and energy loss reduction by raking into account the cost of capacitors. The problem is formulated as a mixed integer

M. E. Baran; F. F. Wu

1989-01-01

387

ARIES-CS Radial Builds and Compositions  

E-print Network

everywhere (no shield-only zones). · 1% nuclear heating in LT shield and/or VV. · Shield, VV, and magnet Configuration R = 8.25 m a = 1.85 m #12;08/30/2004 10 Internal VV #12;08/30/2004 11 Flibe/FS Radial Build (Water

388

Geometric Derivation of Radial Acceleration Magnitude.  

ERIC Educational Resources Information Center

Standard treatments of uniform circular motion generally employ a combination of geometric and kinematic arguments to obtain the magnitude of radial acceleration. Presents a novel approach to the geometric portion of the derivation that uses the property that vectors can be translated parallel to themselves. (JRH)

Kraft, David W.; Motz, Lloyd

1995-01-01

389

Radial Structure of the Runaway Electron Diffusion  

E-print Network

Radial Structure of the Runaway Electron Diffusion Coefficient in Tokamaks R. Sánchez, J.R. Martín Electron Diffusion Coefficient in Tokamaks #12;Introduction: Runaway electrons · Electrons become runaways Optimizing loop Analysis of limiter JET discharge Conclusions #12;Introduction: Runaway transport · Transport

Martín-Solís, José Ramón

390

Determining Enzyme Activity by Radial Diffusion  

ERIC Educational Resources Information Center

Discusses advantages of radial diffusion assay in determining presence of enzyme and/or rough approximation of amount of enzyme activities. Procedures are included for the preparation of starch-agar plates, and the application and determination of enzyme. Techniques using plant materials (homogenates, tissues, ungerminated embryos, and seedlings)…

Davis, Bill D.

1977-01-01

391

Experimental Characterization of Piezoelectric Radial Field Diaphragms for Fluidic Control  

NASA Technical Reports Server (NTRS)

NASA has recently developed a new piezoelectric actuator, the Radial Field Diaphragm or RFD. This actuator uses a radially-directed electric field to generate concentric out-of-plane (Z-axis) motion that allows this packaged device to be used as a pump or valve diaphragm. In order to efficiently use this new active device, experimental determination of pressure, flow rate, mechanical work, power consumption and overall efficiency needs to be determined by actually building a pump. However, without an optimized pump design, it is difficult to assess the quality of the data, as these results are inherent to the actual pump. Hence, separate experiments must be conducted in order to generate independent results to help guide the design criteria and pump quality. This paper focuses on the experiments used to generate the RFD's operational parameters and then compares these results to the experimentally determined results of several types of ball pumps. Also discussed are how errors are inherently introduced into the experiments, the pump design, experimental hardware and their effects on the overall system efficiency.

Bryant, R. G.; Kavli, S. E.; Thomas, R. A., Jr.; Darji, K. J.; Mossi, K. M.

2004-01-01

392

Micro-polarimeter for high performance liquid chromatography  

DOEpatents

A micro-polarimeter interfaced with a system for high performance liquid chromatography, for quantitatively analyzing micro and trace amounts of optically active organic molecules, particularly carbohydrates. A flow cell with a narrow bore is connected to a high performance liquid chromatography system. Thin, low birefringence cell windows cover opposite ends of the bore. A focused and polarized laser beam is directed along the longitudinal axis of the bore as an eluent containing the organic molecules is pumped through the cell. The beam is modulated by air gap Faraday rotators for phase sensitive detection to enhance the signal to noise ratio. An analyzer records the beams's direction of polarization after it passes through the cell. Calibration of the liquid chromatography system allows determination of the quantity of organic molecules present from a determination of the degree to which the polarized beam is rotated when it passes through the eluent.

Yeung, Edward E. (Ames, IA); Steenhoek, Larry E. (Wilmington, DE); Woodruff, Steven D. (Morgantown, WV); Kuo, Jeng-Chung (Skokie, IL)

1985-01-01

393

Automated gas chromatography  

DOEpatents

An apparatus and process for the continuous, near real-time monitoring of low-level concentrations of organic compounds in a liquid, and, more particularly, a water stream. A small liquid volume of flow from a liquid process stream containing organic compounds is diverted by an automated process to a heated vaporization capillary where the liquid volume is vaporized to a gas that flows to an automated gas chromatograph separation column to chromatographically separate the organic compounds. Organic compounds are detected and the information transmitted to a control system for use in process control. Concentrations of organic compounds less than one part per million are detected in less than one minute.

Mowry, Curtis D. (Albuquerque, NM); Blair, Dianna S. (Albuquerque, NM); Rodacy, Philip J. (Albuquerque, NM); Reber, Stephen D. (Corrales, NM)

1999-01-01

394

Cooled variable-area radial turbine technology program  

NASA Technical Reports Server (NTRS)

The objective of this study was a conceptual evaluation and design analyses of a cooled variable-area radial turbine capable of maintaining nearly constant high efficiency when operated at a constant speed and pressure ratio over a range of flows corresponding to 50- to 100-percent maximum engine power. The results showed that a 1589K (2400 F) turbine was feasible that would satisfy a 4000-hour duty cycle life goal. The final design feasibility is based on 1988 material technology goals. A peak aerodynamic stage total efficiency of 0.88 was predicted at 100 percent power. Two candidate stators were identified: an articulated trailing-edge and a locally movable sidewall. Both concepts must be experimentally evaluated to determine the optimum configuration. A follow-on test program is proposed for this evaluation.

Large, G. D.; Meyer, L. J.

1982-01-01

395

Zinc Uptake and Radial Transport in Roots of Arabidopsis thaliana: A Modelling Approach to Understand Accumulation  

E-print Network

Zinc uptake in roots is believed to be mediated by ZIP (ZRT-, IRT- like Proteins) transporters. Once inside the symplast, zinc is transported to the pericycle, where it exits by means of HMA (Heavy Metal ATPase) transporters. The combination of symplastic transport and spatial separation of influx and efflux produces a pattern in which zinc accumulates in the pericycle. Here, mathematical modelling was employed to study the importance of ZIP regulation, HMA level and symplastic transport in creation of the radial pattern of zinc in primary roots of Arabidopsis thaliana. A comprehensive one-dimensional dynamical model of radial zinc transport in roots was developed and used to conduct simulations. The model accounts for the structure of the root consisting of symplast and apoplast and includes effects of water flow, diffusion, and cross-membrane transport via transporters. It also incorporates the radial geometry and varying porosity of root tissues, as well as regulation of ZIP transporters. Steady state patt...

Claus, Juliane; Chavarría-Krauser, Andrés

2012-01-01

396

Polysaccharides Chiral Stationary Phases in Liquid Chromatography  

Microsoft Academic Search

Chiral resolution has achieved an independent identity in the separation sciences and polysaccharide CSPs are viewed as effective and efficient CSPs due to their many unique advantages. The present review article highlights the separations of chiral pharmaceuticals and drugs by liquid chromatographic modalities (high performance liquid chromatography, capillary electro?chromatography, sub? and super critical fluid chromatography and thin layer chromatography) utilizing

Imran Ali; Kishwar Saleem; Iqbal Hussain; Vinay D. Gaitonde

2009-01-01

397

Chromatography (LC/GC) Online  

NSDL National Science Digital Library

Chromatography (LC/GC) Online magazine is a very good source for relatively short articles about fundamental chromatographic issues as well as applications. The content is appropriate for introductory analytical courses (e.g. quant) and for instrumental analysis courses.

398

Radial inlet guide vanes for a combustor  

DOEpatents

A combustor may include an interior flow path therethrough, a number of fuel nozzles in communication with the interior flow path, and an inlet guide vane system positioned about the interior flow path to create a swirled flow therein. The inlet guide vane system may include a number of windows positioned circumferentially around the fuel nozzles. The inlet guide vane system may also include a number of inlet guide vanes positioned circumferentially around the fuel nozzles and adjacent to the windows to create a swirled flow within the interior flow path.

Zuo, Baifang; Simons, Derrick; York, William; Ziminsky, Willy S

2013-02-12

399

Capillary-channeled polymer (C-CP) fibers as a stationary phase in microbore high-performance liquid chromatography columns.  

PubMed

Microbore columns utilizing polypropylene capillary-channeled polymer (C-CP) fibers as the stationary phase in high-performance liquid chromatography (HPLC) have been investigated. The polypropylene C-CP fiber diameter is approximately 50 microm, with eight channels along the periphery of the fiber ranging in diameter from approximately 12 to 35 microm. The polypropylene C-CP fibers were packed into fluorinated ethylene propylene (FEP) tubing, 1.3 mm inner diameter, with lengths of 500, 750, and 1,000 mm, to examine the effects of increased column length with regards to plate height, resolution and analysis time. The low backpressures characteristic of the C-CP fiber stationary phases allow the length of the column to be increased without significantly decreasing the specific permeability. The high specific permeability (approximately 5x10(-8) cm2) of the C-CP packed microbore columns yields a relatively low backpressure of 2.35 MPa at the highest flow rate of 17 microL/s (54 mm/s) for a 1,000 mm column. Radial compression of the soft-walled FEP tubing is accomplished by pulling the 1.7 mm o.d. column through a 1.4 mm diameter orifice. Reducing the inner diameter of the column from 1.3 to 1.0 mm lowered the interstitial fraction from 47% to 42%, decreased the A-term contributions to band broadening, resulted in a significant decrease in average plate height (approximately 30%), and increased resolution (approximately 36%) at identical linear velocities. Although the lower void volume of the radially compressed column increased the backpressure from 0.57 to 2.11 MPa at a linear velocity of approximately 20 mm/s, the specific permeability only decreased from approximately 7x10(-8) to 4x10(-8) cm2. PMID:16283270

Stanelle, Rayman D; Mignanelli, Massimiliano; Brown, Phil; Marcus, R Kenneth

2006-01-01

400

Surface diffusion in reversed-phase liquid chromatography.  

PubMed

More than 40 years ago, Giddings pointed out in "Dynamics of Chromatography" that surface diffusion should become an important research topic in the kinetics of chromatographic phenomena. However, few studies on surface diffusion in adsorbents used in chromatography were published since then. Most scientists use ordinary rate equations to study mass transfer kinetics in chromatography. They take no account of surface diffusion and overlook the significant contributions of this mass transfer process to chromatographic behavior and to column efficiency at high mobile phase flow rate. Only recently did the significance of surface diffusion in separation processes begin to be recognized in connection with the development of new techniques of fast flow, high efficiency chromatography. In this review, we revisit the reports on experimental data on surface diffusion and introduce a surface-restricted molecular diffusion model, derived as a first approximation for the mechanism of surface diffusion, on the basis of the absolute rate theory. We also explain how this model accounts for many intrinsic characteristics of surface diffusion that cannot properly be explained by the conventional models of surface diffusion. PMID:20137790

Miyabe, Kanji; Guiochon, Georges

2010-03-12

401

Surface diffusion in reversed-phase liquid chromatography  

SciTech Connect

More than 40 years ago, Giddings pointed out in 'Dynamics of Chromatography' that surface diffusion should become an important research topic in the kinetics of chromatographic phenomena. However, few studies on surface diffusion in adsorbents used in chromatography were published since then. Most scientists use ordinary rate equations to study mass transfer kinetics in chromatography. They take no account of surface diffusion and overlook the significant contributions of this mass transfer process to chromatographic behavior and to column efficiency at high mobile phase flow rate. Only recently did the significance of surface diffusion in separation processes begin to be recognized in connection with the development of new techniques of fast flow, high efficiency chromatography. In this review, we revisit the reports on experimental data on surface diffusion and introduce a surface-restricted molecular diffusion model, derived as a first approximation for the mechanism of surface diffusion, on the basis of the absolute rate theory. We also explain how this model accounts for many intrinsic characteristics of surface diffusion that cannot properly be explained by the conventional models of surface diffusion.

Miyabe, Kanji [Toyama University, Japan; Guiochon, Georges A [ORNL

2010-01-01

402

Structural radial heterogeneity of a silica-based wide-bore monolithic column  

SciTech Connect

The radial distribution of the main characteristics (elution time and standard deviation) of the elution profiles of a flat injected band recorded at the exit of a monolithic column were determined. These distributions provide the radial distributions of the average mobile phase velocity, the elution time and the maximum height of the peak of an analyte, the column efficiency and the analyte concentration. The band profiles were measured at the exit of a 10-mm i.d., 100-mm long silica-based monolithic column. An on-column local electrochemical amperometric detector allowed the recording of the elution profiles at different spatial positions throughout the column cross-section. The local spatial distribution of the mobile phase velocity does not follow a piston-flow behavior but exhibits radial heterogeneity. The local efficiency near the wall is lower than that near the column center. The radial distribution of the maximum concentration of the peaks varies throughout the column exit section, partially due to the radial variations of the column efficiency. These results might explain the rather large value of the A term of the Van Deemter or the Knox equations reported previously for monolithic columns.

Mriziq, Khaled S [ORNL; Guiochon, Georges A [ORNL

2008-01-01

403

Effects of the radial inflow of gas and galactic fountains on the chemical evolution of M 31  

NASA Astrophysics Data System (ADS)

Context. Galactic fountains and radial gas flows are very important ingredients for modeling the chemical evolution of galactic disks. Aims: Our aim here is to study the effects of galactic fountains and radial gas flows on the chemical evolution of the disk of Andromeda (M 31) galaxy. Methods: We adopt a ballistic method to study the effects of galactic fountains on the chemical enrichment of the M 31 disk by analyzing the landing coordinate of the fountains and the time delay in the pollution of the interstellar gas. To understand the consequences of radial flows, we adopt a very detailed chemical evolution model. Our aim is to study the formation of abundance gradients along the M 31 disk and also compare our results with the Milky Way. Results: We find that the landing coordinate for the fountains in M 31 is no more than 1 kpc from the starting point, thus producing a negligible effect on the chemical evolution of the disk. We find that the delay time in the enrichment process due to fountains is no longer than 100 Myr, and this timescale also produces insignificant effects on the results. Then, we compute the chemical evolution of the M 31 disk with radial gas flows produced by the infall of extragalactic material and fountains. We find that a moderate inside-out formation of the disk, coupled with radial flows of variable speed, can reproduce the observed gradient very well. We also discuss the effects of other parameters, such as a threshold in the gas density for star formation and efficiency of star formation varying with the galactic radius. Conclusions: We conclude that galactic fountains do not affect the chemical evolution of the M 31 disk. Including radial gas flows with an inside-out formation of the disk produces a very good agreement with observations. On the other hand, if radial flows are not considered, one should assume a threshold in the star formation and variable star formation efficiency, besides the inside-out formation to reproduce the data. We conclude that the most important physical processes in creating disk gradients are the inside-out formation and the radial gas flows. More data on abundance gradients both locally and at high redshift are necessary to confirm this conclusion.

Spitoni, E.; Matteucci, F.; Marcon-Uchida, M. M.

2013-03-01

404

Determination of nanogram per liter concentrations of volatile organic compounds in water by capillary gas chromatography and selected ion monitoring mass spectrometry and its use to define groundwater flow directions in Edwards Aquifer, Texas  

USGS Publications Warehouse

A method has been developed to measure nanogram per liter amounts of selected volatile organic compounds (VOCs) including dichlorodifluoromethane, trichlorofluoromethane, cis-1,2-dichloroethene, trichloroethene, tetrachloroethene, and the isomers of dichlorobenzene in water. The method uses purge-and-trap techniques on a 100 mL sample, gas chromatography with a megabore capillary column, and electron impact, selected ion monitoring mass spectrometry. Minimum detection levels for these compounds ranged from 1 to 4 ng/L in water. Recoveries from organic-free distilled water and natural groundwater ranged from 70.5% for dichlorodifluoromethane to 107.8% for 1,4-dichlorobenzene. Precision was generally best for cis-1,2-dichloroethene, tetrachloroethene, and the dichlorobenzene isomers and worst for dichlorodifluoromethane and trichlorofluoromethane. Blank data indicated persistent, trace-level introduction of dichlorodifluoromethane, 1,4-dichlorobenzene, and tetrachloroemene to samples during storage and shipment at concentrations less than the method reporting limits. The largest concentrations of the selected VOCs in 27 water samples from the Edwards aquifer near San Antonio, TX, were from confined-zone wells near an abandoned landfill. The results defined a zone of water with no detectable VOCs in nearly all of the aquifer west of San Antonio and from part of the confined zone beneath San Antonio.

Buszka, P.M.; Rose, D.L.; Ozuna, G.B.; Groschen, G.E.

1995-01-01

405

SpicyNodes Radial Map Engine  

NASA Astrophysics Data System (ADS)

The need for information has increased exponentially over the past decades. The current systems for constructing, exploring, classifying, organizing, and searching information face the growing challenge of enabling their users to operate efficiently and intuitively in knowledge-heavy environments. This paper presents SpicyNodes, an advanced user interface for difficult interaction contexts. It is based on an underlying structure known as a radial map, which allows users to manipulate and interact in a natural manner with entities called nodes. This technology overcomes certain limitations of existing solutions and solves the problem of browsing complex sets of linked information. SpicyNodes is also an organic system that projects users into a living space, stimulating exploratory behavior and fostering creative thought. Our interactive radial layout is used for educational purposes and has the potential for numerous other applications.

Douma, M.; Ligierko, G.; Angelov, I.

2008-10-01

406

On radial anisotropy limits in stellar systems  

NASA Astrophysics Data System (ADS)

Following earlier authors we re-examine the upper limits on the radial velocity anisotropy of general stellar systems; these constraints coming generically from phase-space density positivity, stability, and separability. Galaxy models almost always satisfy an inequality ? < ?/2, i.e. the radial anisotropy is locally no greater than half of the logarithmic density slope. Some complex separable models are the only known cases which disobey this inequality and do so by having an exceptionally large anisotropy at the centre. Here we present new families of non-separable but simple models which have ? > ?/2. Such large, superthreshold anisotropy always occurs in a finite region in between an isotropic core and an isotropic outer boundary. Our models are always self-consistent and hence maintain the positivity of the phase-space density. Nevertheless, regions with superthreshold anisotropy are potentially subject to secular instability and may thus be observed in a short-lived phase of galaxies.

Barber, Jeremy A.; Zhao, Hongsheng

2014-08-01

407

Traumatic Epithelial Downgrowth After Radial Keratotomy  

PubMed Central

A 40 year-old Caucasian male, status post radial keratotomy OU in 1993, suffered pain, extreme photophobia, and mild loss of uncorrected visual acuity in the right eye after being struck by a nail. The patient presented with a small deep stromal lesion and was initially treated with a variety of antibiotic regimens without improvement in the lesion’s appearance. Upon referral the patient had confocal microscopy performed, which clearly demonstrated epithelial cells in the deep stroma and on the endothelial surface. Upon cessation of all medications the patient’s mild symptoms resolved, and his clinical appearance has remained stable without intervention for 9 months. Patients with radial keratotomy incisions are at risk for traumatic epithelial downgrowth even many years after surgery. Confocal microscopy can make the definitive diagnosis of epithelial downgrowth. Management of this condition remains controversial. PMID:18242462

Nemi, Ajit; Bahadur, Rosanna P.; Randleman, J. Bradley

2013-01-01

408

Simple proposal for radial 3D needlets  

NASA Astrophysics Data System (ADS)

We present here a simple construction of a wavelet system for the three-dimensional ball, which we label radial 3D needlets. The construction envisages a data collection environment in which an observer located at the center of the ball is surrounded by concentric spheres with the same pixelization at different radial distances, for any given resolution. The system is then obtained by weighting the projector operator built on the corresponding set of eigenfunctions and performing a discretization step which turns out to be computationally very convenient. The resulting wavelets can be shown to have very good localization properties in the real and harmonic domain; their implementation is computationally very convenient, and they allow for exact reconstruction as they form a tight frame system. Our theoretical results are supported by an extensive numerical analysis.

Durastanti, C.; Fantaye, Y.; Hansen, F.; Marinucci, D.; Pesenson, I. Z.

2014-11-01

409

Automated gas chromatography  

DOEpatents

An apparatus and process for the continuous, near real-time monitoring of low-level concentrations of organic compounds in a liquid, and, more particularly, a water stream. A small liquid volume of flow from a liquid process stream containing organic compounds is diverted by an automated process to a heated vaporization capillary where the liquid volume is vaporized to a gas that flows to an automated gas chromatograph separation column to chromatographically separate the organic compounds. Organic compounds are detected and the information transmitted to a control system for use in process control. Concentrations of organic compounds less than one part per million are detected in less than one minute. 7 figs.

Mowry, C.D.; Blair, D.S.; Rodacy, P.J.; Reber, S.D.

1999-07-13

410

Radial SI latches vibration test data review  

NASA Technical Reports Server (NTRS)

Dynamic testing of the Space Telescope Scientific Instrument Radial Latches was performed as specified by the designated test criteria. No structural failures were observed during the test. The alignment stability of the instrument simulator was within required tolerances after testing. Particulates were discovered around the latch bases, after testing, due to wearing at the B and C latch interface surfaces. This report covers criteria derivation, testing, and test results.

Harrison, P. M.; Smith, J. L.

1984-01-01

411

Model for radial forging of superalloys  

SciTech Connect

The goal of process modeling is to optimize existing processes, design new processes, and determine causes and/or corrective actions for specific manufacturing problems. Models for most of Allvac`s processes have now been developed, using a combination of in-house proprietary computer codes and commercially available software. This article describes how process modeling has been successfully applied at Allvac in the key process of radial forging.

Minisandram, R.S. [Teledyne Allvac, Monroe, NC (United States)

1995-10-01

412

On Radially Symmetric Solutions to Conservation Laws  

Microsoft Academic Search

\\u000a Radially symmetric solutions to multi-dimensional systems of conservations laws are important in applications and computations,\\u000a as well as in the general theory of conservative systems. Notwithstanding their one-dimensional nature they are poorly understood.\\u000a In particular this is true for the Euler equations in gas-dynamics. After a short review of symmetric solutions to the Euler\\u000a system, we introduce a scalar model

Helge Kristian Jenssen

413

The IRAF radial velocity analysis package  

NASA Technical Reports Server (NTRS)

The IRAF Radial Velocity Analysis package is described and future plans are presented. A discussion of the current strengths and weaknesses of the package is given along with an analysis of the accuracies that can be expected for a given data set. An overview of the cross-correlation task is presented along with atypical examples of it's use. Future plans for new tasks and algorithms are also described.

Fitzpatrick, M.

1992-01-01

414

Variational method for integrating radial gradient field  

NASA Astrophysics Data System (ADS)

We propose a variational method for integrating information obtained from circular fringe pattern. The proposed method is a suitable choice for objects with radial symmetry. First, we analyze the information contained in the fringe pattern captured by the experimental setup and then move to formulate the problem of recovering the wavefront using techniques from calculus of variations. The performance of the method is demonstrated by numerical experiments with both synthetic and real data.

Legarda-Saenz, Ricardo; Brito-Loeza, Carlos; Rivera, Mariano; Espinosa-Romero, Arturo

2014-12-01

415

Measurement of the radial density gradient of cosmic ray in the heliosphere by the GRAPES-3 experiment  

NASA Astrophysics Data System (ADS)

A radial anisotropy in the flux of cosmic rays in heliosphere was theoretically predicted by Parker and others within the framework of the diffusion-convection mechanism. The solar wind is responsible for sweeping out the galactic cosmic rays, creating a radial density gradient within the heliosphere. This gradient coupled with the interplanetary magnetic field induces a flow of charged particles perpendicular to the ecliptic plane which was measured and correctly explained by Swinson, and is hereafter referred as 'Swinson flow'. The large area GRAPES-3 tracking muon telescope offers a powerful probe to measure the Swinson flow and the underlying radial density gradient of the galactic cosmic rays at a relatively high rigidity of ?100 GV. The GRAPES-3 data collected over a period of six years (2000-2005) were analyzed and the amplitude of the Swinson flow was estimated to be (0.0644 ± 0.0008)% of cosmic ray flux which was an ?80? effect. The phase of the maximum flow was at a sidereal time of (17.70 ± 0.05) h which was 18 min earlier than the expected value of 18 h. This small 18 min phase difference had a significance of ?6? indicating the inherent precision of the GRAPES-3 measurement. The radial density gradient of the galactic cosmic rays at a median rigidity of 77 GV was found to be 0.65% AU-1.

Kojima, H.; Antia, H. M.; Dugad, S. R.; Gupta, S. K.; Hayashi, Y.; Jagadeesan, P.; Jain, A.; Kawakami, S.; Mohanty, P. K.; Nonaka, T.; Oshima, A.; Rao, B. S.; Shibata, S.

2015-03-01

416

Sample injector for high pressure liquid chromatography  

DOEpatents

Apparatus and method for driving a sample, having a well-defined volume, under pressure into a chromatography column. A conventional high pressure sampling valve is replaced by a sample injector composed of a pair of injector components connected in series to a common junction. The injector components are containers of porous dielectric material constructed so as to provide for electroosmotic flow of a sample into the junction. At an appropriate time, a pressure pulse from a high pressure source, that can be an electrokinetic pump, connected to the common junction, drives a portion of the sample, whose size is determined by the dead volume of the common junction, into the chromatographic column for subsequent separation and analysis. The apparatus can be fabricated on a substrate for microanalytical applications.

Paul, Phillip H. (Livermore, CA); Arnold, Don W. (Livermore, CA); Neyer, David W. (Castro Valley, CA)

2001-01-01

417

Sample displacement batch chromatography of proteins.  

PubMed

In downstream processing large scale chromatography plays an important role. For its development screening experiments followed by pilot plant chromatography are mandatory steps. Here we describe fast, simple, and inexpensive methods for establishing a preparative chromatography for the separation of complex protein mixtures, based on sample displacement batch chromatography. The methods are demonstrated by anion-exchange chromatography of a human plasma protein fraction (Cohn IV-4), including the screening step and scaling up of the chromatography by a factor of 100. The results of the screening experiments and the preparative chromatography are monitored by SDS-PAGE electrophoresis. In summary we provide a protocol which should be easily adaptable for the chromatographic large scale purification of other proteins, in the laboratory as well as in industry for commercial manufacturing. For the latter these protocols cover the initial piloting steps for establishing a sample batch chromatography based on packed columns rather than batch chromatography. PMID:24648085

Kotasinska, Marta; Richter, Verena; Kwiatkowski, Marcel; Schlüter, Hartmut

2014-01-01

418

Polar Fourier transforms of radially sampled NMR data  

Microsoft Academic Search

Radial sampling of the NMR time domain has recently been introduced to speed up data collection significantly. Here, we show that radially sampled data can be processed directly using Fourier transforms in polar coordinates. We present a comprehensive theoretical analysis of the discrete polar Fourier transform, and derive the consequences of its application to radially sampled data using linear response

Brian E. Coggins; Pei Zhou

2006-01-01

419

Precision cold die forging of a ring gear by divided flow method  

Microsoft Academic Search

The process utilizing divided material flow is applied to working a ring gear. When the specimen is of a larger height and the ratio of the height to the radial thickness is large, the central material flow in the radial direction produces a time lag in both the upper and a lower material flow which causes a product defect. The

K. Kondo; K. Ohga

1995-01-01

420

Observation of Plasma Flow at the Magnetic Island in the Large Helical Device  

Microsoft Academic Search

Radial profiles of ion temperature and plasma flow are measured at the n\\/m = 1\\/1 magnetic island produced by external perturbation coils in the Large Helical Device. The sheared poloidal flows and sheared radial electric field are observed at the boundaries of the magnetic island, because the poloidal flow vanishes inside the static magnetic island. When the width of the

K. Ida; N. Ohyabu; T. Morisaki; Y. Nagayama; S. Inagaki; K. Itoh; Y. Liang; K. Narihara; A. Yu. Kostrioukov; B. J. Peterson; K. Tanaka; T. Tokuzawa; K. Kawahata; H. Suzuki; A. Komori

2002-01-01

421

A numerical inversion of a the Laplace transform solution to radial dispersion in a porous medium.  

USGS Publications Warehouse

A special form of the numerical inversion of the Laplace transform described by Stehfest (1970) is applied to the transformed solution of dispersion in a radial flow system in a porous medium. The inversion is extremely simple to use because the weighting coefficients depend only on the number of terms used in the computation and not upon the transform solution as required by most numerical inversion techniques.-from Authors

Moench, A.F.; Ogata, A.

1981-01-01

422

Spacelab experiments on convection in a rotating spherical shell with radial gravity  

NASA Astrophysics Data System (ADS)

Experiments on thermal convection in a rotating, differentially-heated hemispherical shell of fluid with a radial gravity field were carried out in the microgravity environment of Spacelab 3 which was flown on the space shuttle Challenger in May 1985. Schlieren visualizations of these laboratory flows are compared briefly to three-dimensional nonlinear simulations that can be conducted at the more modest heating rates.

Toomre, J.; Hart, J. E.; Glatzmaier, G. A.

423

High-performance displacement chromatography-mass spectrometry of tryptic peptides of recombinant human growth hormone.  

PubMed

The combination of high-performance displacement chromatography with continuous flow fast atom bombardment (FAB)-mass spectrometry (MS) offers a means of overcoming the sample capacity limitations imposed by the low flow-rates tolerated in microbore systems employed for directly coupled liquid chromatography-MS. Displacement chromatography is performed at high concentrations with the same equipment and columns as typically used in chromatography at low concentrations. By using this mode of chromatography with a solution of cetyltrimethylammonium bromide as the displacer, the capacity of a reversed-phase column can be increased 50- to 100-fold for separation of a tryptic digest of biosynthetic human growth hormone. Despite the high load, the use of displacement chromatography allowed high-resolution separation of the complex mixture of eighteen major components. On-line analysis by continuous flow FAB-MS yielded high-quality spectra of these peptides and demonstrated that sharp, single-component bands can be obtained in this separation. Along with the major fragments, the chromatogram showed other peptides originating from protein variants in the sample, from non-specific cleavage in the enzymatic digest or from autolysis of trypsin. On-line analysis also allowed selective ion monitoring of the column effluent for individual peptides and confirmed the high efficiency and resolution obtained by preparative displacement separations on HPLC columns and equipment. PMID:2229231

Frenz, J; Bourell, J; Hancock, W S

1990-07-20

424

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

PubMed

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

Rybár, Ivan; Góra, Robert; Hutta, Milan

2007-12-01

425

Validation of noninvasive MOEMS-assisted measurement system based on CCD sensor for radial pulse analysis.  

PubMed

Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner's subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation. PMID:23609803

Malinauskas, Karolis; Palevicius, Paulius; Ragulskis, Minvydas; Ostasevicius, Vytautas; Dauksevicius, Rolanas

2013-01-01

426

Validation of Noninvasive MOEMS-Assisted Measurement System Based on CCD Sensor for Radial Pulse Analysis  

PubMed Central

Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner?s subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation. PMID:23609803

Malinauskas, Karolis; Palevicius, Paulius; Ragulskis, Minvydas; Ostasevicius, Vytautas; Dauksevicius, Rolanas

2013-01-01

427

Instrumentation for hand-portable liquid chromatography.  

PubMed

Liquid chromatography (LC) has lagged behind gas chromatography (GC) in developments related to hand-portable instrumentation. In this work, a new battery-operated (24V DC) nano-flow pumping system with a stop-flow injector was developed and integrated with an on-column UV-absorption detector (254nm) that was reduced in size to an acceptable weight and power usage for field operation. The pumping system, which includes nano-flow pump, stepper motor and high-pressure valve weighs only 1.372kg (3lbs) and can generate up to 110.32MPa (16,000psi) pressure. A major advantage of this pump is that it does not employ a splitter, since it was specifically designed for capillary column use. The volume capacity of the pump is 24?L, and a sample volume as low as 10nL can be injected. Flow rate calibration (300nL to 6.12?L per min) was performed, and an accuracy >99.94% was obtained. The percent injection carry-over was found to be low (RSD 0.31%), which makes it practical for quantitative analysis. The detector linear range and limit of detection (LOD) were determined using sodium anthraquinone-2-sulfonate. A linear regression coefficient (R) of 0.9996 was obtained for a plot of log peak area versus log concentration over the range of 3.2?M to 6.5mM, and the LOD (S/N=3) was found to be 7.8fmol (0.13?M). The short term noise of the detector is comparable to commercially available detectors (?10(-5)AU). In this work, the system was tested in the laboratory using regular line power (120V AC) with an AC to DC adapter. Reversed-phase isocratic separations were performed using a 15.5cm×75?m i.d. fused silica capillary column containing a monolithic stationary phase synthesized from 1,6-hexanediol dimethacrylate. Good retention time repeatability (RSD 0.09-0.74%) was obtained for a mixture containing an unretained marker (i.e., uracil) and a homologous series of alkyl benzenes. PMID:24411999

Sharma, Sonika; Plistil, Alex; Simpson, Robert S; Liu, Kun; Farnsworth, Paul B; Stearns, Stanley D; Lee, Milton L

2014-01-31

428

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

429

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

430

Optical implementations of radial basis classifiers.  

PubMed

We describe two optical systems based on the radial basis function approach to pattern classification. An optical-disk-based system for handwritten character recognition is demonstrated. The optical system computes the Euclidean distance between an unknown input and 650 stored patterns at a demonstrated rate of 26,000 pattern comparisons/s. The ultimate performance of this system is limited by optical-disk resolution to 10(11) binary operations/s. An adaptive system is also presented -that facilitates on-line learning and provides additional robustness. PMID:20820272

Neifeld, M A; Psaltis, D

1993-03-10

431

Polarization singularities of focused, radially polarized fields  

NASA Astrophysics Data System (ADS)

The state of polarization of strongly focused, radially polarized electromagnetic fields is examined. It is found that several types of polarization singularities exist. Their relationship is investigated, and it is demonstrated that on smoothly varying a system parameter, such as the aperture angle of the lens, different polarization singularities can annihilate each other. For example, the evolution of a lemon into a monstar and its subsequent annihilation with a star is studied. Also, the quite rare collision of a C-line and an L -line, resulting in a V-point, is observed.

Schoonover, R. W.; Visser, T. D.

2006-06-01

432

Radial visualizations for comparative data analysis  

NASA Astrophysics Data System (ADS)

SQiRL is a novel visualization system for querying and visualizing large multivariate data sets. Although initially designed for novice users, recent extensions to SQiRL facilitate more advanced analysis without sacrificing the simplicity that makes this visualization appealing to beginners. The default view provides a simple-to-learn interface for query evaluation. Intermediate users are provided a straightforward method for comparing the results of two queries. More advanced users can make use of a "radial crosstab," a new interactive visualization technique that melds the expressive power of traditional crosstabulation with a drag-and-drop canvas.

Draper, Geoffrey M.; Styles, Matthew G.; Riesenfeld, Richard F.

2012-01-01

433

A design of coaxial-to-radial line adaptors in radial line slot antennas  

NASA Astrophysics Data System (ADS)

A numerical design of a coaxial-to-radial line adaptor is presented for the use as a feed in a radial line slot antenna. To realize stable performances in mass production, the reflection from a probe type adaptor in which only the outer conductor of a coaxial line is in contact with the waveguide, is analyzed and suppressed. The tolerance for the change and the errors in the height of the waveguide as well as the bandwidth is highlighted; the advantages of the conical probe over the conventional shorting post and the coax-gap adaptor are emphasized.

Natori, Makoto; Ando, Makoto; Goto, Naohisa

1990-11-01

434

Comparing radial and femoral access for coronary angiography and interventions.  

PubMed

Cardiac catheterization and coronary intervention via the radial approach is increasingly adopted as the preferred vascular access to avoid transfemoral vascular complications. Recent clinical trials have confirmed that radial access reduces vascular complications and local bleeding with similar procedural efficacy. Transradial access has inherent technical challenges, including smaller vessel size of the radial artery, arterial spasm and tortuosity involving the radial and subclavian arteries, which may undermine the procedural success of this approach. A number of strategies have been reported to minimize complications of radial access, including the use of hydrophilic introducer sheaths and smaller sheath sizes, administration of nitroglycerin and unfractionated heparin during the procedure, patent hemostasis of the radial artery and careful patient selection. Operators experienced in transradial percutaneous coronary intervention can achieve comparable clinical outcomes to the transfemoral approach and minimize vascular complications. Radial artery access is likely to become widely accepted as the preferred percutaneous coronary intervention approach. PMID:24236557

Hsieh, Victar; Jolly, Sanjit

2013-03-01

435

Thin-Layer and Paper Chromatography.  

ERIC Educational Resources Information Center

Reviews literature on chromatography examining: books, reviews, student experiments; chromatographic systems, techniques, apparatus; detecting and identification of separated zones; preparative chromatography and radiochromatography; and applications related to specific materials (such as acids, alcohols, amino acids, antibiotics, enzymes, dyes,…

Sherma, Joseph; Fried, Bernard

1984-01-01

436

Chromatography: Are We Getting It Right?  

ERIC Educational Resources Information Center

Explains the basics of chromatography which is used to demonstrate the separation of plant photosynthetic pigments. Reports the results of an evaluative study that explored textbook errors in explaining how chromatography works. (Contains 13 references.) (Author/YDS)

Maitland, Pamela D.; Maitland, David P.

2002-01-01

437

High-field asymmetric waveform ion mobility spectrometry coupled with liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-FAIMS-MS/MS) multi-component bioanalytical method development, performance evaluation and demonstration of the constancy of the compensation voltage with change of mobile phase composition or flow rate.  

PubMed

The feasibility of developing a multi-component bioanalytical method using high-field asymmetric waveform ion mobility spectrometry coupled with liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-FAIMS-MS/MS) is demonstrated using nefazodone and its two metabolites as model compounds. The performance of the bioanalytical method for the three analytes, with three different compensation voltage (CV) values, is assessed using standard curves and quality control samples, which exhibited good accuracy, precision and ruggedness. The number of analytes with different CV values that can be quantitated simultaneously depends on the acquisition cycle time, which is a function of the FAIMS residence time (fixed), chromatographic peak width and selected reaction monitoring (SRM) dwell time. It is established that CV, the FAIMS selectivity parameter, is reproducible for at least 16 h, thus ensuring the constancy of the CV during a large-batch sample analysis. It is also established that change in mobile phase composition or of flow rate does not cause a shift in CV. Thus, CV values determined from a CV scan via infusion of a sample can be used for an LC/ESI-FAIMS-M/MS method based on isocratic or gradient elution. PMID:17939154

Wu, Steven T; Xia, Yuan-Qing; Jemal, Mohammed

2007-01-01

438

Effect of axisymmetric magnetic fields on radial dopant segregation of floating-zone silicon growth in a mirror furnace  

Microsoft Academic Search

The effect of axisymmetric magnetic fields on radial dopant segregation of floating-zone silicon growth in a mirror furnace is studied through computer simulation. The mirror furnace is modeled by a point lamp model, and the magnetic fields are generated by wire coils carrying different currents. Heat and mass transfer, fluid flow, melt\\/solid interfaces, and the free surface are solved globally

C. W. Lan

1996-01-01

439

A radial transmission line material measurement apparatus  

SciTech Connect

A radial transmission line material measurement sample apparatus (sample holder, offset short standards, measurement software, and instrumentation) is described which has been proposed, analyzed, designed, constructed, and tested. The purpose of the apparatus is to obtain accurate surface impedance measurements of lossy, possibly anisotropic, samples at low and intermediate frequencies (vhf and low uhf). The samples typically take the form of sections of the material coatings on conducting objects. Such measurements thus provide the key input data for predictive numerical scattering codes. Prediction of the sample surface impedance from the coaxial input impedance measurement is carried out by two techniques. The first is an analytical model for the coaxial-to-radial transmission line junction. The second is an empirical determination of the bilinear transformation model of the junction by the measurement of three full standards. The standards take the form of three offset shorts (and an additional lossy Salisbury load), which have also been constructed. The accuracy achievable with the device appears to be near one percent.

Warne, L.K.; Moyer, R.D.; Koontz, T.E.; Morris, M.E.

1993-05-01

440

Measuring Radial Velocities of Extragalactic Planetary Nebulae  

NASA Astrophysics Data System (ADS)

Planetary Nebulae (PNe) are excellent kinematic probes of old stars in nearby galaxies. They are extremely bright in [O III], present in stellar populations with ages between 0.1 and 10 Gyr, and their radial velocities can be measured to 3 km/s precision with fiber-fed spectrographs. Narrow-band imaging has been used to identify between 40 and 500 PN candidates in six nearby spirals (IC 342, M74, M94, M101, NGC 2403, and NGC 6946), as well as >640 possible PNe in the Virgo Cluster. We have recently obtained spectra of a large sample of these extragalactic PN candidates using the Hydra multi-fiber spectrograph on the WIYN telescope. Here we describe the details of applying various IRAF tasks to reduce more than 10,100 spectra (including sky spectra and objects targeted multiple times) and to measure radial velocities and uncertainties. In each of the spirals, the PN velocities clearly show rotation at a speed slightly less than the gas, demonstrating the presence of asymmetric drift. The spectra from the targets in the Virgo Cluster fields are a mixture of true PNe and background Lyman Alpha Emitting galaxies (LAEs). The PN velocities and LAE galaxy spectra will be further analyzed elsewhere. This research was part of the NAU summer REU program and we gratefully acknowledge funding from the National Science Foundation (AST-1004107).

Gillman, Farris; Herrmann, K. A.; Ciardullo, R.

2012-01-01

441

Multiepoch Radial Velocity Observations of L Dwarfs  

E-print Network

We report on the development of a technique for precise radial-velocity measurements of cool stars and brown dwarfs in the near infrared. Our technique is analogous to the Iodine (I2) absorption cell method that has proven so successful in the optical regime. We rely on telluric CH4 absorption features to serve as a wavelength reference, relative to which we measure Doppler shifts of the CO and H2O features in the spectra of our targets. We apply this technique to high-resolution (R~50,000) spectra near 2.3 micron of nine L dwarfs taken with the Phoenix instrument on Gemini-South and demonstrate a typical precision of 300 m/s. We conduct simulations to estimate our expected precision and show our performance is currently limited by the signal-to-noise of our data. We present estimates of the rotational velocities and systemic velocities of our targets. With our current data, we are sensitive to companions with M sin i > 2MJ in orbits with periods less than three days. We identify no companions in our current data set. Future observations with improved signal-to-noise should result in radial-velocity precision of 100 m/s for L dwarfs.

Cullen H. Blake; David Charbonneau; Russel J. White; Mark S. Marley; Didier Saumon

2007-05-26

442

Precise Near-Infrared Radial Velocities  

NASA Astrophysics Data System (ADS)

We present precise radial velocity time-series from a 2.3 micron near-infrared survey to detect exoplanets around ~30 red, low mass, and young stars. We use the CSHELL spectrograph (R~46,000) at the NASA InfraRed Telescope Facility, combined with an isotopic methane absorption gas cell for common optical path relative wavelength calibration. We have developed a sophisticated RV forward modeling code that accounts for fringing and other instrumental artifacts present in the spectra (see poster by Gao et al. at this meeting). We are able to reach long-term radial velocity dispersions of ~15-30 m/s on our survey targets. With a spectral grasp of only 5 nm, this performance is near the expected photon and detector noise limit. We highlight future applications of our instrumentation and RV forward modeling code to iSHELL at IRTF (R~75,000), and an upgraded NIRSPEC on the Keck II telescope (R~50,000). With the increased spectral grasp of both spectrometers, we should be able to obtain a precision of less than 5 m/s in the near-infrared.

Plavchan, Peter; Gao, Peter; Gagne, Jonathan; Furlan, Elise; Bottom, Michael; Davison, Cassy; Mills, Sean; Ciardi, David R.; Tanner, Angelle M.; Beichman, Charles A.; Catanzarite, Joseph; Johnson, John; White, Russel J.; Anglada-Escudé, Guillem; Henry, Todd J.; von Braun, Kaspar; Walp, Bernie; Prato, Lisa A.

2015-01-01

443

Comparative chromatography of chloroplast pigment  

NASA Technical Reports Server (NTRS)

Methods for isolation of low concentration pigments of the cocklebur species are described. The methods entail two step chromatography so that the different sorption properties of the various pigments in varying column parameters can be utilized. Columnar and thin layer methods are compared. Many conditions influence separability of the chloroplasts.

Grandolfo, M.; Sherma, J.; Strain, H. H.

1969-01-01

444

Undergraduate Separations Utilizing Flash Chromatography  

NASA Astrophysics Data System (ADS)

This article describes the procedures used to carry out four flash chromatography experiments: the isolation of the carotenes, chlorophylls and xanthophylls from a spinach extract; the separation of ß-carotene from tetraphenyl cyclopentadienone; the isolation of (+) and (-) carvone from caraway and spearmint oil; and the purification of benzil from benzoin. Apparatus used is nonbreakable, easy to use, and inexpensive.

Horowitz, G.

2000-02-01

445

From gas chromatography to gaia  

Microsoft Academic Search

This paper is an account of the development of the gaia hypothesis as seen through the eyes of a gas chromatographer. Gaia is a radical notion about the Earth which postulates the climate and chemical composition to be regulated at an optimum by and for life. Gas chromatography played an important role in the gathering of evidence for the hypothesis

J. E. Lovelock

1982-01-01

446

Illustrating Chromatography with Colorful Proteins  

ERIC Educational Resources Information Center

Advances in biology are prompting new discoveries in the biotechnology, pharmaceutical, medical technology, and chemical industries. This paper presents a detailed description of an anion exchange chromatography experiment using a pair of colorful proteins and summarizes the effect of operating parameters on protein separation. This experiment…

Lefebvre, Brian G.; Farrell, Stephanie; Dominiak, Richard S.

2007-01-01

447

Soil & Water Lab, Ion Chromatography Procedure Page 1 Ion Chromatography Procedure  

E-print Network

Soil & Water Lab, Ion Chromatography Procedure Page 1 Ion Chromatography Procedure Last updated: 5.29.13 A. Introduction Ion chromatography (IC) is used to separate out various ions based on their charge if a new machine part is needed. D. Stock Solution Preparation #12;Soil & Water Lab, Ion Chromatography

Walter, M.Todd

448

Journal of Chromatography A, 807 (1998) 111119 Microemulsion electrokinetic chromatography of fatty acids as  

E-print Network

Journal of Chromatography A, 807 (1998) 111­119 Microemulsion electrokinetic chromatography by microemulsion electrokinetic chromatography. Separations were done by using an untreated fused-silica capillary/w) and n-butanol (6.55%, w/w), pH 10.2. Separation by microemulsion electrokinetic chromatography

Miksik, Ivan

449

ORIGINAL ARTICLE A new liquid chromatography method  

E-print Network

ORIGINAL ARTICLE A new liquid chromatography method for the simultaneous and sensitive and lactulose using high performance liquid chromatography (HPLC) and evaporative light scattering detection/2010034 This article should be cited as: Schuster-Wolff-Bühring R. et al., A new liquid chromatography

Boyer, Edmond

450

The Convergence of Multicomponent Chromatography with Relaxation  

E-print Network

The Convergence of Multicomponent Chromatography with Relaxation Alberto Bressan and Wen Shen SISSA of multicomponent chromatography, and the zero relaxation limit is a n�n system of conserva­ tion laws of Temple and preliminary In this paper we consider the system of multicomponent chromatography: # # # # # u t + u x = - 1

Shen, Wen

451

The Convergence of Multicomponent Chromatography with Relaxation  

E-print Network

The Convergence of Multicomponent Chromatography with Relaxation Alberto Bressan and Wen Shen SISSA of multicomponent chromatography, and the zero relaxation limit is a nÃ?n system of conserva- tion laws of Temple and preliminary In this paper we consider the system of multicomponent chromatography: ut + ux = - 1 (F(u) - v

Shen, Wen

452

BV Estimates for Multicomponent Chromatography with Relaxation  

E-print Network

BV Estimates for Multicomponent Chromatography with Relaxation Alberto Bressan and Wen Shen S (2000), pp.21-39. 1 #12; The model for n-component chromatography ( u t + ux = 1 " (F (u) v) v t = 1. (more...) Recent results on systems: Bressan & Shen(2000): Chromatography Bianchini (2000): relaxation

Shen, Wen

453

Interactions of radially outgoing jets through gaps between periodically arranged bars in a circle  

NASA Astrophysics Data System (ADS)

Mutual interactions of jets radially spouting from gaps between periodically arranged sector-shaped bars in a circle are investigated. Confluences of jets were confirmed by flow visualization and numerical simulation assuming a two-dimensional and incompressible flow field. The jets are independent of each other at small Reynolds numbers, but interact in a complex manner to yield various flow patterns such as confluences of several jets or oscillatory flows synchronized in the same phase between several jets. We found that the confluence of two or three steady jets occurs due to a pitchfork bifurcation and that the synchronized oscillation is a consequence of a Hopf bifurcation. Quasi-periodic oscillation in jets was also found and confirmed to originate from a Neimark-Sacker bifurcation; i.e., a Hopf bifurcation for maps. The critical Reynolds numbers for these bifurcations were determined numerically for various values of the pitch-to-nozzle-width ratio.

Takemoto, Yukio; Mizushima, Jiro

2006-09-01

454

A parametric study of penetration and mixing of radial jets in necked-down cylindrical crossflow  

NASA Astrophysics Data System (ADS)

This paper summarizes a parametric study of the penetration and mixing performance of radial jets injected from slots into necked-down cylindrical crossflow, which is characteristic of a generic tubular RQL combustor quick-mix section. The analysis considers only nonreacting flows to concentrate on the fluid mechanics aspect of the processes using temperature as a passive scalar to characterize the mixing performance. Parameters considered are momentum flux ratios of the mixing jets to the cross flow, number of injection holes, and the aspect ratios of the slotted holes. The overall mass-flux ratio of jet to cross flow (equivalence ratio) is kept constant. The effects due to the neck-down ratios, swirling cross flow, and slanted slots on the mixing performance are also presented for selected cases. The implications of the parametric study on designing the optimal mixer geometry is discussed in terms of temperature uniformity and pressure penalty.

Zhu, G.; Lai, M.-C.

1992-07-01

455

Initial experiments using radial foils on the Cornell Beam Research Accelerator pulsed power generator  

NASA Astrophysics Data System (ADS)

A novel technique involving radial foil explosions can produce high energy density plasmas. A current flows radially inward in a 5 ?m thin aluminum foil from a circular anode, which contacts the foil on its outer rim, to the cathode, which connects to the foil at its geometrical center. When using small "pin" cathodes (˜1 mm in diameter) on a medium size pulsed-current generator such as the Cornell Beam Research Accelerator, the central magnetic field approaches 400 T, yielding magnetic pressures larger than 0.5 Mbar. While the dynamics is similar to radial wire arrays, radial foil discharges have very distinct characteristics. First a plasma jet forms, with densities near 5×1018 cm-3. J×B forces lift the foil upward with velocities of ˜200 km/s. A plasma bubble with electron densities superior to 5×1019 cm-3 then develops, surrounding a central plasma column, carrying most of the cathode current. X-ray bursts coming from the center of this column were recorded at 1 keV photon energy. As the magnetic bubble explodes, ballistic plasma projectiles form and escape with velocities exceeding 300 km/s. Laser shadowgraphy and interferometry, gated extreme ultraviolet imaging and miniature Bdot probes are used to investigate the magnetohydrodynamics properties of such configurations.

Gourdain, P.-A.; Blesener, I. C.; Greenly, J. B.; Hammer, D. A.; Knapp, P. F.; Kusse, B. R.; Schrafel, P. C.

2010-01-01

456

Fabricating Radial Groove Gratings Using Projection Photolithography  

NASA Technical Reports Server (NTRS)

Projection photolithography has been used as a fabrication method for radial grove gratings. Use of photolithographic method for diffraction grating fabrication represents the most significant breakthrough in grating technology in the last 60 years, since the introduction of holographic written gratings. Unlike traditional methods utilized for grating fabrication, this method has the advantage of producing complex diffractive groove contours that can be designed at pixel-by-pixel level, with pixel size currently at the level of 45 45 nm. Typical placement accuracy of the grating pixels is 10 nm over 30 nm. It is far superior to holographic, mechanically ruled or direct e-beam written gratings and results in high spatial coherence and low spectral cross-talk. Due to the smooth surface produced by reactive ion etch, such gratings have a low level of randomly scattered light. Also, due to high fidelity and good surface roughness, this method is ideally suited for fabrication of radial groove gratings. The projection mask is created using a laser writer. A single crystal silicon wafer is coated with photoresist, and then the projection mask, with its layer of photoresist, is exposed for patterning in a stepper or scanner. To develop the photoresist, the fabricator either removes the exposed areas (positive resist) of the unexposed areas (negative resist). Next, the patterned and developed photoresist silicon substrate is subjected to reactive ion etching. After this step, the substrate is cleaned. The projection mask is fabricated according to electronic design files that may be generated in GDS file format using any suitable CAD (computer-aided design) or other software program. Radial groove gratings in off-axis grazing angle of incidence mount are of special interest for x-ray spectroscopy, as they allow achieving higher spectral resolution for the same grating area and have lower alignment tolerances than traditional in-plane grating scheme. This is especially critical for NASA Constellation- X project that will utilize hundreds of gratings all of which need to be precisely aligned for x-ray observation of space.

Iazikov, Dmitri; Mossberg, Thomas W.

2009-01-01

457

Two-dimensional countercurrent chromatography × high performance liquid chromatography for preparative isolation of toad venom.  

PubMed

In this work, a new on-line two-dimensional chromatography coupling of flow programming counter-current chromatography and high-performance liquid chromatography (2D CCC×HPLC) was developed for preparative separation of complicated natural products. The CCC column was used as the first dimensional isolation and a preparative ODS column operated in reversed-phase (RP) mode as the second dimension. The CCC was operated at a controlled flow rate to ensure that each fraction eluted within one hour, corresponding to the isolation time of the 2nd dimensional preparative HPLC. The eluent from the 1st dimensional CCC was diluted using a makeup pump and trapped onto holding column, before been eluted and transferred to the 2nd dimensional HPLC. The performance of the holding column was evaluated, in terms of column size, dilution ratio and diameter-height ratio, as well as system pressure, for the solution to the issue of online trapping of low pressure eluent from a CCC column. Satisfactory trapping efficiency and tolerable CCC pressure can be achieved using a commercially available 15mm×30mm i.d. ODS pre-column. The present integrated system was successfully applied in a one-step preparative separation of 12 compounds, from the crude methanol extract of venom of Bufo bufo gargarizans. Compounds 1-12 were isolated in overall yield of 1.0%, 0.8%, 2.0%, 1.3%, 2.0%, 1.5%, 1.9%, 3.6%, 6.1%, 4.8%, 3.5% and 4.1%, with HPLC purity of 99.9%, 99.7%, 90.6%, 99.9%, 77.0%, 99.9%, 90.4%, 99.9%, 52.0%, 99.9%, 99.3%, and 85.0%, respectively. All the results demonstrate that the flow programming CCC×HPLC method is an efficient and convenient way for the separation of compounds from toad venom and it can also be applied to isolate other complex multi-component natural products. PMID:24484689

Qiu, Ying-Kun; Yan, Xia; Fang, Mei-Juan; Chen, Lin; Wu, Zhen; Zhao, Yu-Fen

2014-02-28

458

Efficiency of supercritical fluid chromatography columns in different thermal environments.  

PubMed

The efficiency of a packed column eluted with supercritical carbon dioxide at 323K and outlet pressures from 90 to 150bar was studied with the column in two different thermal environments. The 150mm×2.0mm ID stainless steel column was packed with spherical 5-?m porous silica particles with a covalently bonded nonpolar stationary phase, and the test solutes were normal alkanes. When operated in a convective air bath the column exhibited severe efficiency losses when its outlet pressure was below 120bar. The efficiency of the same column enclosed in a shell made of foam insulation was restored at low outlet pressures down to 100bar. The van Deemter plots showed an abnormal dependence of the plate height (HETP) on the flow rate at low outlet pressures, exhibiting a maximum in the HETP at flow rates around 1mL/min and a 20-bar pressure drop. The large efficiency losses at low outlet pressures are due to radial temperature gradients associated with enthalpic expansion and cooling of the mobile phase. The separations were simulated by a numerical model that accounts for axial and radial gradients in the temperature and density along the column. The abnormal van Deemter plots arise from competing processes affecting the radial distribution of the solute migration velocity along the column. The negative impact on efficiency is greatest when the density profile of the mobile phase along the column is close to the critical isopycnic line. The efficiency improves at increased flow rates because of increased cooling at larger pressure drops and increased density along the entire length of the column. The model predicts the unusual trends in the van Deemter plots, but the calculated results at low outlet pressures are strongly influenced by small variations in the porosity distribution in the column, limiting the accuracy of the predicted HETP values. In spite of these difficulties, the m