Note: This page contains sample records for the topic radial flow chromatography from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Study on the purification of polysaccharides from Noscoc flagelliforme with radial flow chromatography  

Microsoft Academic Search

The isolation and purification of polysaccharide from Noscoc flagelliforme by radial flow chromatography were studied. The column (7.7 cm of bed length and 229.6 cm3 of bed volume) was packed with DEAE-01 anion ion-exchange resin and gradient eluted with NaCl solutions. The content of the\\u000a polysaccharide was determined with the phenol-sulfuric acid method. The effects of sampling weight, elution velocity,

Yu-Jie Dai; Jing-Wen Wang; Shi-Ru Jia; Si-Jun Yue; Meng-Yao Jia; Peng Xu

2009-01-01

2

Experimental consideration of capillary chromatography based on tube radial distribution of ternary mixture carrier solvents under laminar flow conditions.  

PubMed

A capillary chromatography system has been developed based on the tube radial distribution of the carrier solvents using an open capillary tube and a water-acetonitrile-ethyl acetate mixture carrier solution. This tube radial distribution chromatography (TRDC) system works under laminar flow conditions. In this study, a phase diagram for the ternary mixture carrier solvents of water, acetonitrile, and ethyl acetate was constructed. The phase diagram that included a boundary curve between homogeneous and heterogeneous solutions was considered together with the component ratios of the solvents in the homogeneous carrier solutions required for the TRDC system. It was found that the TRDC system performed well with homogeneous solutions having component ratios of the solvents that were positioned near the homogeneous-heterogeneous solution boundary of the phase diagram. For preparing the carrier solutions of water-hydrophilic/hydrophobic organic solvents for the TRDC system, we used for the first time methanol, ethanol, 1,4-dioxane, and 1-propanol, instead of acetonitrile (hydrophilic organic solvent), as well as chloroform and 1-butanol, instead of ethyl acetate (hydrophobic organic solvent). The homogeneous ternary mixture carrier solutions were prepared near the homogeneous-heterogeneous solution boundary. Analyte mixtures of 2,6-naphthalenedisulfonic acid and 1-naphthol were separated with the TRDC system using these homogeneous ternary mixture carrier solutions. The pressure change in the capillary tube under laminar flow conditions might alter the carrier solution from homogeneous in the batch vessel to heterogeneous, thus affecting the tube radial distribution of the solvents in the capillary tube. PMID:21415507

Jinno, Naoya; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2011-01-01

3

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.

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

2013-01-01

4

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

5

Stability of radial swirl flows  

NASA Astrophysics Data System (ADS)

The energy gradient theory is used to examine the stability of radial swirl flows. It is found that the flow of free vortex is always stable, while the introduction of a radial flow will induce the flow to be unstable. It is also shown that the pure radial flow is stable. Thus, there is a flow angle between the pure circumferential flow and the pure radial flow at which the flow is most unstable. It is demonstrated that the magnitude of this flow angle is related to the Re number based on the radial flow rate, and it is near the pure circumferential flow. The result obtained in this study is useful for the design of vaneless diffusers of centrifugal compressors and pumps as well as other industrial devices.

Dou, H. S.; Khoo, B. C.

2012-11-01

6

Zonal rate model for axial and radial flow membrane chromatography, part II: Model-based scale-up.  

PubMed

Membrane chromatography (MC) systems are finding increasing use in downstream processing trains for therapeutic proteins due to the unique mass-transfer characteristics they provide. As a result, there is increased need for model-based methods to scale-up MC units using data collected on a scaled-down unit. Here, a strategy is presented for MC unit scale-up using the zonal rate model (ZRM). The ZRM partitions an MC unit into virtual flow zones to account for deviations from ideal plug-flow behavior. To permit scale-up, it is first configured for the specific device geometry and flow profiles within the scaled-down unit so as to achieve decoupling of flow and binding related non-idealities. The ZRM is then configured for the preparative-scale unit, which typically utilizes markedly different flow manifolds and membrane architecture. Breakthrough is first analyzed in both units under non-binding conditions using an inexpensive tracer to independently determine unit geometry related parameters of the ZRM. Binding related parameters are then determined from breakthrough data on the scaled-down MC capsule to minimize sample requirements. Model-based scale-up may then be performed to predict band broadening and breakthrough curves on the preparative-scale unit. Here, the approach is shown to be valid when the Pall XT140 and XT5 capsules serve as the preparative and scaled-down units, respectively. In this case, scale-up is facilitated by our finding that the distribution of linear velocities through the membrane in the XT140 capsule is independent of the feed flow rate and the type of protein transmitted. Introduction of this finding into the ZRM permits quantitative predictions of breakthrough over a range of industrially relevant operating conditions. Biotechnol. Bioeng. 2014;111: 1587-1594. © 2014 Wiley Periodicals, Inc. PMID:24554490

Ghosh, Pranay; Lin, Min; Vogel, Jens H; Choy, Derek; Haynes, Charles; von Lieres, Eric

2014-08-01

7

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

8

Radial flow pulse jet mixer  

DOEpatents

The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

VanOsdol, John G.

2013-06-25

9

Stirling Engine With Radial Flow Heat Exchangers  

NASA Technical Reports Server (NTRS)

Conflict between thermodynamical and structural requirements resolved. In Stirling engine of new cylindrical configuration, regenerator and acceptor and rejector heat exchangers channel flow of working gas in radial direction. Isotherms in regenerator ideally concentric cylinders, and gradient of temperature across regenerator radial rather than axial. Acceptor and rejector heat exchangers located radially inward and outward of regenerator, respectively. Enables substantial increase in power of engine without corresponding increase in diameter of pressure vessel.

Vitale, N.; Yarr, George

1993-01-01

10

Radial distribution load flow using conic programming  

Microsoft Academic Search

This paper shows that the load flow problem of a radial distribution system can be modeled as a convex optimization problem, particularly a conic program. The implications of the conic programming formulation are threefold. First, the solution of the distribution load flow problem can be obtained in polynomial time using interior-point methods. Second, numerical ill-conditioning can be automatically alleviated by

Rabih A. Jabr

2006-01-01

11

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

12

Probabilistic load flow in radial distribution networks  

Microsoft Academic Search

This paper presents a modification of the general analytical probabilistic load flow methodology, used primarily in the analysis of composite systems. Some appropriate approximations are introduced and the radial operating structure of power distribution systems is also utilized. This has resulted in significant simplification of the general methodology. It is now much more easier to obtain sensitivity coefficients and matrix

A. Dimitrovski; R. Ackovski

1996-01-01

13

Radial vorticity constraint in core flow modeling  

NASA Astrophysics Data System (ADS)

We present a new method for estimating core surface flows by relaxing the tangentially geostrophic (TG) constraint. Ageostrophic flows are allowed if they are consistent with the radial component of the vorticity equation under assumptions of the magnetostrophic force balance and an insulating mantle. We thus derive a tangentially magnetostrophic (TM) constraint for flows in the spherical harmonic domain and implement it in a least squares inversion of GRIMM-2, a recently proposed core field model, for temporally continuous core flow models (2000.0-2010.0). Comparing the flows calculated using the TG and TM constraints, we show that the number of degrees of freedom for the poloidal flows is notably increased by admitting ageostrophic flows compatible with the TM constraint. We find a significantly improved fit to the GRIMM-2 secular variation (SV) by including zonal poloidal flow in TM flow models. Correlations between the predicted and observed length-of-day variations are equally good under the TG and TM constraints. In addition, we estimate flow models by imposing the TM constraint together with other dynamical constraints: either purely toroidal (PT) flow or helical flow constraint. For the PT case we cannot find any flow which explains the observed SV, while for the helical case the SV can be fitted. The poor compatibility between the TM and PT constraints seems to arise from the absence of zonal poloidal flows. The PT flow assumption is likely to be negated when the radial magnetostrophic vorticity balance is taken into account, even if otherwise consistent with magnetic observations.

Asari, S.; Lesur, V.

2011-11-01

14

Pseudo-shock in radial supersonic flow  

NASA Astrophysics Data System (ADS)

The static and dynamic properties of a pseudo-shock in a radial supersonic flow between two parallel plates were investigated. The length and pressure recovery of the pseudo-shock were smaller than those in a constant-area duct. Pressure fluctuations at two different points along the radius were simultaneously measured and were statistically correlated, so that the propagation of pressure fluctuation was obtained. They had two main frequencies, high and low ones, which propagated in different directions.

Yamane, R.; Oshima, S.; Takahashi, M.; Tamaki, H.

1985-01-01

15

Power Flow Analysis for Balanced and Unbalanced Radial Distribution Systems  

Microsoft Academic Search

This paper reports on an efficient method of power flow analysis for solving balanced and unbalanced radial distribution systems. The radial distribution system is modelled as a series of interconnected single feeders. Using Kirchoff's laws, a set of iterative power flow equations was developed to conduct the power flow studies. Due to the voltage dependency of loads in distribution systems,

H. M. Mok; S. Elangovan; M. M. A. Salama; Cao Longjian

16

Experimental investigation of nanofluids in confined laminar radial flows  

Microsoft Academic Search

This paper presents an experimental investigation of heat transfer enhancement capabilities of coolants with suspended nanoparticles (Al2O3 dispersed in water) inside a radial flow cooling device. Steady, laminar radial flow of a nanofluid between a heated disk and a flat plate with axial coolant injection has been considered. An experimental test rig was built. Results show that heat transfer enhancements

Iulian Gherasim; Gilles Roy; Cong Tam Nguyen; Dinh Vo-Ngoc

2009-01-01

17

Fast decoupled power flow for unbalanced radial distribution systems  

Microsoft Academic Search

This paper presents a novel power flow formulation and an effective solution method for general unbalanced radial distribution systems. Comprehensive models are considered including lines, switches, transformers, shunt capacitors, cogenerators, and several types of loads. A new problem formulation of three-phase distribution power flow equations taking into account the radial structure of the distribution network is presented. A distinguishing feature

Ray D. Zimmerman; Hsiao-Dong Chiang

1995-01-01

18

New findings on radial distribution system load flow algorithms  

Microsoft Academic Search

In this paper, an attempt has been made to comprehensively compare the two most commonly used distribution load flow (DISTFLOW) models for radial networks to decide the better of the two for practical application. The paper also presents another novel method for radial distribution load flow and demonstrates its superiority over the two said models. Results have been obtained by

J. Nanda; M. S. Srinivas; S. S. Dey; L. L. Lai

2000-01-01

19

Load flow solution of radial distribution feeders: a new contribution  

Microsoft Academic Search

This paper presents a new development for solving the load flow problem for radial distribution feeders, without having to solve the well-known conventional load flow equations. The algorithm details are discussed. Two test radial distribution feeders are solved using the proposed development to illustrate the technique. The tables of solution variables such as voltage, injected powers at each node of

S. F Mekhamer; S. A Soliman; M. A Moustafa; M. E El-Hawary

2002-01-01

20

Thermal Diffusivity Measurement by a Radial Heat Flow Method.  

National Technical Information Service (NTIS)

A method is presented whereby the thermal diffusivity of a solid is measured by observing the temperature excursion which results from a radial flow of heat. The radial heat flow is produced by the instantaneous deposition of energy on a disk region of on...

A. B. Donaldson R. E. Taylor

1975-01-01

21

Radial flow retorting process with trays and downcomers  

Microsoft Academic Search

Solid heat carrier material and solid hydrocarbon-containing material, such as oil shale, tar sands or coal, are deflected by conical baffles into radially moving fluid beds which alternately flow radially outwardly and inwardly over a series of trays and downwardly into a series of peripheral and axial downcomers for a sufficient residence time to liberate hydrocarbons from the solid hydrocarbon-containing

Oltrogge

1983-01-01

22

Prediction of radial transport efficiency in slug flow  

NASA Astrophysics Data System (ADS)

The momentum and radial heat/mass transfer in slug flow is investigated by using a finite difference numerical procedure. Both friction factors and Nusselt numbers are derived for Reynolds numbers varying from 5 to 100 and Peclet numbers from 50 to 1000. These results are compared to the corresponding classical results for homogeneous laminar flow at identical flow rate. A significant enhancement in radial transport is demonstrated in the case of slug flow for the whole range of the parameters studied. However, it is concluded that improvement of the global radial transport efficiency in slug flow, with respect to homogeneous flow situations, is not always achieved owing to mechanical energy requirements for pumping the fluid. Criteria for global efficiency improvement are given and appear to depend on both Peclet number, slug aspect ratio, and void fraction of the slug flow.

Antonini, G.; Guiffant, G.

1980-12-01

23

Optimal power flow in radial distribution systems  

Microsoft Academic Search

Radial distribution systems (RDS) have lines with high R\\/X ratios and hence Newton based methods were not reliable to solve their set of bus power balance equations. Historically, a recursive solution method using a set of voltage equations and its variants are very popular to determine a voltage solution of a RDS. Consequently, use of classical optimization was not possible.

B. Venkatesh

2010-01-01

24

A simple algorithm for unbalanced radial distribution system load flow  

Microsoft Academic Search

Many programs of real-time applications in the area of distribution automation, such as network optimization, Var planning, switching, state estimation, and so forth, require a robust and efficient load flow method for distribution systems. Such a load flow method must be able to model the special features of distribution systems in sufficient detail. Many approaches for unbalanced radial distribution system

Sivkumar Mishra

2008-01-01

25

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

26

Radial vorticity constraint in the core flow modeling  

NASA Astrophysics Data System (ADS)

We study the compatibility of core flow models with the radial vorticity constraint (RVC) arising from the assumption of electrically insulating mantle. A necessary condition of the RVC has been derived from the radial component of the quasi-steady, and diffusionless, vorticity equation just below the core-mantle boundary (CMB). This condition is a set of integral constraints defined for a given Br model at the CMB, and requires the conservation of radial planetary vorticity within every closed contour of Br = 0. In this work, instead of investigating the integral constraints in the spatial domain, we directly deal with the vorticity equation in the spectral domain. The core flow inversion process is regularized such that the flow components incompatible with that equation are minimized. We here report the effect of this new constraint, in particular when modeling purely toroidal (PT) flow. Outside the new constraint, the method and the input magnetic model (t-CHAOS for 1999.1-2006.0) for the PT flow inversion are fundamentally the same as in Wardinski et al. (2008). It is found that, as the weight for the RVC regularization is increased, the PT flow solution becomes dominated by zonal components. In the limit toward the RVC strictly met, the solution converges to a purely zonal flow which fails to explain the magnetic model. Nonetheless, within reasonable ranges of the misfit to the magnetic model and the flow velocity, there can be a PT flow model with a significant improvement in fitting to the RVC.

Asari, Seiki; Lesur, Vincent

2010-05-01

27

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

28

The vergence eye movements induced by radial optic flow  

PubMed Central

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: the missing fundamental (mf) stimulus. The radial motion consisted of successive ¼-wavelength steps, so that the overall pattern and the 4n+1 harmonics (where n=integer) underwent radial expansion (or contraction), whereas the 4n-1 harmonics—including the strongest Fourier component (the 3rd harmonic)—underwent the opposite radial motion. Radial motion commenced only after the subject had fixated the center of the pattern. The initial RFVRs were always in the direction of the 3rd harmonic, e.g., expansion of the mf pattern causing divergence. Thus, the earliest RFVRs were strongly dependent on the motion of the major Fourier component, consistent with early spatio-temporal filtering prior to motion detection, as in the well-known energy model of motion analysis. If the radial mf stimulus was reduced to just two competing harmonics—the 3rd and 5th—the initial RFVRs showed a nonlinear dependence on their relative contrasts: when the two harmonics differed in contrast by more than about an octave then the one with the higher contrast completely dominated the RFVRs and the one with lower contrast lost its influence: winner-take-all. We suggest that these nonlinear interactions result from mutual inhibition between the mechanisms sensing the motion of the different competing harmonics. If single radial-flow steps were used, a brief inter-stimulus interval resulted in reversed RFVRs, consistent with the idea that the motion detectors mediating these responses receive a visual input whose temporal impulse response function is strongly biphasic. Lastly, all of these characteristics of the RFVR, which we attribute to the early cortical processing of visual motion, are known to be shared by the Ocular Following Response (OFR)—a conjugate tracking (version) response elicited at short-latency by linear motion—and even the quantitative details are generally very similar. Thus, although the RFVR and OFR respond to very different patterns of global motion—radial vs. linear—they have very similar local spatiotemporal properties as though mediated by the same low-level, local-motion detectors, which we suggest are in the striate cortex.

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

2007-01-01

29

Longitudinal Dispersivity in a Radial Diverging Flow Field  

NASA Astrophysics Data System (ADS)

Hydrodynamic dispersion is an important factor controlling contaminant migration in the subsurface environment. However, few comprehensive data sets exist for evaluating the impact of travel distance and site heterogeneity on solute dispersion under non-uniform flow conditions. In addition, anionic tracers are often used to estimate physical transport parameters based on an erroneous assumption of conservative (i.e., non-reactive) behavior. Therefore, a series of field experiments using tritiated water and several other commonly used hydrologic tracers (Br, Cl, FBAs) were conducted in the water-table aquifer on the U.S. Department of Energy's Savannah River Site (Aiken, SC) to evaluate solute transport processes in a diverging radial flow field. For each experiment, tracer-free groundwater was injected for approximately 24 hours at a fixed rate of 56.7 L/min (15 gpm) to establish a forced radial gradient prior to the introduction of a tracer pulse. After the tracer pulse, the forced gradient was maintained throughout the experiment using non-labeled groundwater. Tracer migration was monitored using a set of six sampling wells radially spaced at approximate distances of 1.5, 3, and 4.5 meters from a central injection well. Each sampling well was further divided into three discrete sampling depths that were monitored continuously throughout the course of the tracer experiment. At various time intervals, discrete groundwater samples were collected from all 18 sampling ports for tritium analysis. Longitudinal dispersivity for tritium breakthrough at each sampling location was estimated using analytical approximations of the convection dispersion equation (CDE) for radial flow assuming an instantaneous Dirac pulse and a pulse of known duration. The results were also compared to dispersivity values derived from fitting the tracer data to analytical solutions derived from assuming uniform flow conditions. Tremendous variation in dispersivity values and tracer arrival times were observed between wells located at similar radial distances and between sampling zones within a given well, with multiple arrival peaks observed for some monitoring locations. However, lower dispersivity values were observed for all data sets when fitting the breakthrough data using the radial flow approximations when compared to uniform flow case. In addition, the 95% confidence interval span for the dispersivity estimate was always smaller for the radial flow solution, indicating a better model fit when compared to the uniform flow model. Additional logistical obstacles in conducting such an extensive set of field tracer experiments will also be discussed.

Seaman, J. C.; Wilson, M.; Bertsch, P. M.; Aburime, S. A.

2005-12-01

30

Probabilistic load flow for radial distribution networks with photovoltaic generators  

Microsoft Academic Search

This paper evidences that a good techniques must consider the technical constraints of the radial distribution networks, where the voltage regulation is one of the principal problems to be addressed in distributed generation photovoltaic systems. These techniques are the probabilistic load flow and the Monte Carlo simulation. Loads and distributed generation production are modelled as random variables. Results demonstrate that

F. J. Ruiz-Rodriguez; J. C. Hernandez; F. Jurado

2011-01-01

31

LOAD FLOW SOLUTION OF UNBALANCED RADIAL DISTRIBUTION SYSTEMS  

Microsoft Academic Search

This paper presents a simple three phase load flow method to solve three-phase unbalanced radial distribution system (RDS). It solves a simple algebraic recursive expression of voltage magnitude, and all the data are stored in vector form. The algorithm uses basic principles of circuit theory and can be easily understood. Mutual coupling between the phases has been included in the

J. B. V. SUBRAHMANYAM

2009-01-01

32

Radial distribution system power flow using interval arithmetic  

Microsoft Academic Search

This paper reports on the application of interval arithmetic technique for balanced radial distribution system power flow analysis. Interval arithmetic takes care of the uncertainty in the input parameters and provides strict bounds for the solution of the problem. In this paper, uncertainties only in the input load parameters are considered. The results are compared with the results obtained from

Biswarup Das

2002-01-01

33

A New Power Flow Method in Radial Distribution Systems  

Microsoft Academic Search

In this paper, a new efficient method is proposed for power flow calculation in radial distribution systems. The distribution busines is changing the need to plan and respond to technical change, growth in distributed generation and deregulated power markets. Thus, it is important to improve fundamental analytical tools in distribution systems. This paper proposes a new method for the power

Wataru Ohyoshi; Hiroyuki Mori

2006-01-01

34

Improved algorithm for radial distribution networks load flow solution  

Microsoft Academic Search

The main aim of this paper is to present an improved method to solve load flow problem in balanced radial distribution systems with laterals. The method is efficient and easy to implement. Based on electric circuit laws, this method is iterative and allows the evaluation of both, voltage (rms) values and phase-angles. The phase-angles although of small values become necessary

Abdellatif Hamouda; Khaled Zehar

2011-01-01

35

Mechanized Calculation of Unbalanced Load Flow on Radial Distribution Circuits  

Microsoft Academic Search

This paper describes a computerized method of calculating unbalanced load flow or fault currents on multi-grounded radial distribution circuits. It was developed by engineers of the Baltimore Gas and Electric Company, and is now being used in operating and expanding their distribution system. The basic concept employed is that the electrical characteristics of any portion of an unbalanced 3-phase circuit

R. Berg; E. S. Hawkins; W. W. Pleines

1967-01-01

36

A robust power flow algorithm for radial distribution systems  

Microsoft Academic Search

In this paper, a new algorithm is presented to solve the power flow problem in radial distribution systems. The proposed method takes into account the voltage dependency of static loads, and line charging capacitance. The method is based on the forward and backward voltage calculation by using polynomial voltage equation and KirchofPs Law for each branch. Convergence speed and reliability

U. Eminoglu; M. H. Hocaoglu

2005-01-01

37

Efficient Load Flow Method for Radial Distribution Feeders  

Microsoft Academic Search

This study presents a simple and efficient solution of load flow in distribution systems characterised by their radial configuration and laterals. This iterative method, based on Kirchoff laws, have the merit to evaluate for each node both the voltage root mean square (rms) value and phase-angles. The phase-angles although of weak values become necessary in the reactive energy optimisation problem.

Abdellatif Hamouda; Khaled Zehar

2006-01-01

38

Harmonic load flow method for radial distribution networks  

Microsoft Academic Search

This work presents a novel harmonic load flow formulation for radial distribution systems. The proposed method is based on the backward\\/forward sweep algorithm. Results obtained with this formulation are the same that could be calculated with the well known current injection method for harmonic studies, but in this case, the construction of any network matrix is not necessary. Also, the

I. Archundia-Aranda; R. O. Mota-Palomino

2010-01-01

39

A novel power flow solution methodology for radial distribution systems  

Microsoft Academic Search

This paper presents a novel and efficient procedure for accomplishing the load flow calculations in an electrical radial distribution system. The proposed approach utilizes the forward sweep algorithm for the iterative evaluation of node parameters which is based on the Kirchhoff's current law [KCL] and Kirchhoff's voltage law [KVL]. The methodology has been made suitable for larger distribution systems by

P. Ravi Babu; M. P. V. V. R. Kumar; V. S. Hemachandra; M. P. R. Vanamali

2010-01-01

40

Pseudo-shock in radial supersonic flow with swirl  

Microsoft Academic Search

The static and dynamic properties of a pseudoshock in a radial supersonic flow with a swirl between parallel plates were experimentally investigated. The length and pressure recovery of the pseudoshock were smaller than those in a straight channel. Pressure recovery decreased with a growth of the swirl. Pressure fluctuation at two different points along the radius was statistically correlated, so

R. Yamane; S. Oshima; K. Okada

1984-01-01

41

Reliable load flow technique for radial distribution networks  

Microsoft Academic Search

This paper presents a method to solve the power flow problem in radial distribution networks. In the proposed formulation, the load flow equations are written in terms of new variables resulting in a set of 3N equations (2N linear plus N quadratic) for a network with N+1 buses. A computationally efficient solution scheme based on the Newton-Raphson method is proposed,

A. Gomez Esposito; E. Romero Ramos

1999-01-01

42

Coronal transient phenomena. [solar atmospheric radial flow model  

NASA Technical Reports Server (NTRS)

A hydrodynamical description of outward propagating disturbances from the sun's surface in a model solar atmosphere is considered. Use is made of this model to explain the coronal transient phenomenon. It was found that this radial flow model clearly indicates the mass flow as being continuous, going out from the surface of the sun. Detailed results are presented for the disturbed density, velocity and temperature of the corona up to 6 solar radii.

Wu, S. T.; Han, S. M.

1974-01-01

43

Analysis and performance of radial flow rotary dessicant dehumidifiers  

SciTech Connect

A model is developed to predict the steady periodic performance of a radial flow desiccant wheel. The model is expressed in terms of the same dimensionless parameters that are commonly used in modeling of the conventional axial flow desiccant wheel. In addition a dimensionless geometrical ratio of the volume of the matrix to the volume of the wheel core is found to affect the performance of the wheel. A finite difference technique on staggered grid is used to discretize the governing dimensionless equations. The discretized equations are solved to predict the performance of the desiccant wheel at given values of operation parameters. A sensitivity study is carried out to investigate the effect of changing any of these parameters on the performance of the wheel. The performance of the radial flow desiccant wheel having the same values of the operation parameters.

Elsayed, M.M.; Chamkha, A.J. [Kuwait Univ., Safat (Kuwait). Mechanical and Industrial Engineering Dept.

1997-02-01

44

Radial gas flows and star formation in spiral galaxies  

NASA Astrophysics Data System (ADS)

We present high-resolution (6?) observations of CO in seven nearby spiral galaxies made with the BIMA interferometer. Complementary single-dish data allow us to produce maps that recover flux on all spatial scales down to the interferometer resolution. The CO data are used in conjunction with previously published H I data to search for evidence of radial inflows in galaxy disks. Utilizing the Fourier decomposition of velocity fields developed by Schoenmakers et al. (1997), we construct simple models illustrating the effects of radial inflow, warps, and bar or spiral-arm streaming on the observed Fourier coefficients. In all seven galaxies we find kinematic evidence for warps, elliptical streaming motions, or both. These futures lead to apparent inflow or outflow velocities of up to 50 km s-1, masking the effect of any net radial flows. In the inner disks of NGC 5033 and 5055, where the velocity fields show well-ordered rotation, we place an upper limit of 5 km s -1 on any axisymmetric radial flows. We then consider possible indirect evidence for radial flows, based on gas consumption arguments and radial abundance gradients. Applying extinction corrections that vary with gas density, we find gas depletion times of roughly 1 Gyr in the central regions and increasing with radius, similar to the situation in the Milky Way. Combined with estimates of the birthrate parameter, our results are difficult to reconcile with closed-box evolution models. The observed abundance gradients are also steeper than would be expected for a closed-box model, but could be accounted for with fairly modest (<1 km s-1) radial inflows. Finally we consider the relationship between gas content and the star formation rate as traced by Halpha emission. Depending on the extinction corrections applied, our results support the existence of a Schmidt law with a power-law index of 1.1--1.7. An a1ternative star formation law, in which the star formation timescale is proportional to the orbital timescale, also matches the data if radially varying extinction corrections are used. The gravitational stability parameter Q does not appear to be related to star formation, at least when only the gas is considered; inclusion of the stellar component may be necessary to allow Q ˜ 1 for low gas fractions. We find that the ratio of H I to H 2 increases with galactocentric radius as R 1.5 and propose that it is determined largely by the interstellar pressure. Our results suggest that the interstellar pressure and metallicity control the formation of molecular clouds from H I, whereas star formation in molecular clouds occurs at a roughly constant rate per unit H2 mass.

Wong, Tony Hao

45

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

46

Measurement of gliclazide in plasma by radial compression reversed-phase liquid chromatography.  

PubMed

We describe a rapid, specific, and precise analysis for gliclazide in plasma by radial compression, reversed-phase, "high-performance" liquid chromatography. Gliclazide and the internal standard, 3-chlorogliclazide, are eluted after 4.4 and 6.8 min, respectively. Only 100 microL of plasma and minimal sample workup are required. The limit of detection for gliclazide in plasma is 0.5 mg/L (1.55 mumol/L) at 229 nm. Precision (CV) of the assay for 10 and 1 mg of gliclazide per litre is 2.1% and 6.4%, respectively. PMID:6488522

Charles, B G; Ravenscroft, P J

1984-11-01

47

Radial flows and angular momentum conservation in Galactic chemical evolution  

NASA Astrophysics Data System (ADS)

We study the effects of radial flows on Galactic chemical evolution. A simple analytic scheme is developed prescribing the coupling of infall from the intergalactic medium and radial flows within the disc based on angular momentum conservation. We show that model parameters are tightly constrained by the observed [Fe/H]-abundance gradient in the Galactic disc. By this comparison the average rotational velocity of the onfalling material can be constrained to 0.7 ? v/Vc ? 0.75, or respectively ˜160 km s-1 when assuming a constant disc circular velocity of Vc = 220 km s-1. We test the robustness of this value against the influence of other processes. For a very simple model of inside-out formation this value changes only by ?v/Vc ˜ 0.1, i.e. ˜20 km s-1, and significantly less on more realistic scenarios, showing that inside-out formation does not alone explain the abundance gradient. Effects of other uncertain parameters, e.g. star formation history and star formation efficiency, have very small impact. Other drivers of inflow beyond our explicit modelling are assessed by adding a fixed inflow across the whole disc. The churning amplitude only mildly affects the results mostly by slightly flattening the metallicity gradient in the inner disc. A new process causing radial gas flows due to the ejection of material by stars moving on non-circular orbits is studied and seems to contribute negligibly to the total flows. We further show that gaseous outer discs cannot be the main source feeding the persistent star formation in the inner regions by a direct inflow.

Bilitewski, Thomas; Schönrich, Ralph

2012-11-01

48

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

49

Characterizing gaseous flow in submicron chromatography columns.  

SciTech Connect

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

Wong, Chung-Nin Channy

2003-05-01

50

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

51

Instability of the radial flow over a rotating disk in a separated edgewise stream  

NASA Astrophysics Data System (ADS)

We present velocity field measurements showing the instability of the radial flow over a rotating disk in a separated flow due to an edgewise freestream. A uniform edgewise stream significantly modifies the radial jet profile. Under separated flow conditions, co-rotating vortical structures form at the edge of the radial jet layer. The results establish that the discrete structures formed in the breakup of the radial flow layer on a rotor blade in retreating blade stall are also seen in the case of flow over a rotating disk.

Raghav, Vrishank; Komerath, Narayanan

2013-11-01

52

Pseudo-shock in radial supersonic flow with swirl  

NASA Astrophysics Data System (ADS)

The static and dynamic properties of a pseudoshock in a radial supersonic flow with a swirl between parallel plates were experimentally investigated. The length and pressure recovery of the pseudoshock were smaller than those in a straight channel. Pressure recovery decreased with a growth of the swirl. Pressure fluctuation at two different points along the radius was statistically correlated, so that the mechanism of propagation of a pressure fluctuation could be analyzed. There were two main fluctuations with high and low frequencies and propagating in opposite directions. The former was excited by an oscillation of the air column in the exhaust chamber and propagated upstream as a pressure wave, while the latter was due to an oscillation of the first shock and was convected downstream.

Yamane, R.; Oshima, S.; Okada, K.

1984-07-01

53

Integrated SPPS on continuous-flow radial microfluidic chip.  

PubMed

A novel integrated continuous-flow microfluidic system was designed and fabricated for solid phase peptide synthesis (SPPS) using conventional reactants. The microfluidic system was composed of a glass-based radial reaction chip, a diffluent chip, amino acid feeding reservoirs and continuous-flow reagent pathways. A tri-row cofferdam-fence structure was designed for solid phase supports trapping. Highly cross-linked, porous and high-loading 4-(hydroxymethyl)phenoxymethyl polystyrene (HMP) beads were prepared for microfluidic SPPS. The transfer losses, hazardous handling and time-consuming processes in traditional peptide cleavage steps were avoided by being replaced with the on-chip cleavage treatment. Six peptides from an antibody affinity peptide library against ?-endorphin with different lengths and sequences were obtained simultaneously on the constructed continuous-flow microfluidic system within a short time. This microfluidic system is automatic, integrated, effective, low-cost, recyclable and environment-friendly for not only SPPS but also other solid phase chemical syntheses. PMID:21270975

Wang, Weizhi; Huang, Yanyan; Liu, Jizhong; Xie, Yunfeng; Zhao, Rui; Xiong, Shaoxiang; Liu, Guoquan; Chen, Yi; Ma, Huimin

2011-03-01

54

Experimental and numerical study of radial flow and its contribution to wake development of a HAWT  

Microsoft Academic Search

The scope of this work was to investigate radial flow component for a Horizontal Axis Wind Turbine in axial flow conditions and to assess its impact on the turbine operation. This was done by means of Particle Image Velocimetry and numerical simulation with a 3D unsteady potential-flow panel model. A direct comparison between the numerical and experimental radial velocity results

D. Micallef; B. Akay; T. Sant; C. J. Simao Ferreira; G. J. W. Van Bussel

2011-01-01

55

Boiling radial flow in fractures of varying wall porosity  

SciTech Connect

The focus of this report is the coupling of conductive heat transfer and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed differences in boiling regimes and behavior, and attempted to quantify a boiling convection coefficient. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials. Nonporous and impermeable aluminum, highly porous and permeable Berea sandstone, and minimally porous and permeable graywacke from The Geysers geothermal field. On nonporous surfaces, the heat flux was not strongly coupled to injection rate into the fracture. However, for porous surfaces, heat flux, and associated values of excess temperature and a boiling convection coefficient exhibited variation with injection rate. Nucleation was shown to occur not upon the visible surface of porous materials, but a distance below the surface, within the matrix. The depth of boiling was a function of injection rate, thermal power supplied to the fracture, and the porosity and permeability of the rock. Although matrix boiling beyond fracture wall may apply only to a finite radius around the point of injection, higher values of heat flux and a boiling convection coefficient may be realized with boiling in a porous, rather than nonporous surface bounded fracture.

Barnitt, Robb Allan

2000-06-01

56

A robust three phase power flow algorithm for radial distribution systems  

Microsoft Academic Search

An efficient load flow solution technique is required as a part of the distribution automation (DA) system for taking various control and operations decisions. This paper presents an efficient and robust three phase power flow algorithm for application to radial distribution networks. This method exploits the radial nature of the network and uses forward and backward propagation to calculate branch

D. Thukaram; H. M. Wijekoon Banda; Jovitha Jerome

1999-01-01

57

A Novel Load Flow Method for Radial Distribution Systems for Realistic Loads  

Microsoft Academic Search

The need for fast load flow algorithms for radial distribution networks that take advantage of their particular structure has been increasing for planning and optimization. In this article, a novel load flow method of radial distribution systems is presented. In the proposed method, different realistic loads have been considered, as loads are voltage dependent in distribution systems. The effect of

K. Nagaraju; S. Sivanagaraju; T. Ramana; P. V. Prasad

2011-01-01

58

A New Approach to Load Flow Solutions for Radial Distribution System  

Microsoft Academic Search

This paper presents a new approach to load flow solutions for radial distribution system, in which the choice of the switches to be opened is based on the calculation of voltage at the buses, real and reactive power flowing through lines, real power losses and voltage deviation, using distribution load flow (DLF) program. In the process of load flow calculation,

T. Thakur; J. Dhiman

2006-01-01

59

Buoyancy-driven flow reversal phenomena in radially rotating serpentine ducts  

SciTech Connect

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 rotational axis to the location of flow separation in the radial-outward duct decreases with increasing the Richardson number. In addition, the local buoyancy that is required to yield the radial flow reversal increases with increasing the rotation number. This buoyancy-driven reversed flow in the radial-outward duct always results in local hot spots in the cooling channels. The critical buoyancy for the initiation of flow reversal is therefore concluded for the design purpose.

Hwang, J.J.; Wang, W.J.; Chen, C.K.

2000-02-01

60

The benefits of looping a radial distribution system with a power flow controller  

Microsoft Academic Search

In this paper the benefits of looping the conventional radial distribution system by a series power electronic system to control power flow has been investigated. The conventional radial electrical distribution system will change to loop or even meshed system due to the deregulation of electrical system and connection of Distributed Generation to Medium and Low voltage in future. However looping

M. Saradarzadeh; S. Farhangi; J. L. Schanen; P.-O. Jeannin; D. Frey

2010-01-01

61

Incorporation of Uncertainties in Radial Distribution System Load Flow with Voltage-dependent Loads  

Microsoft Academic Search

In this article, application of interval arithmetic is proposed for considering the uncertainties of the input parameters in the power flow solution of a balanced radial distribution system with voltage-dependent loads. The uncertainties in both the feeder parameters and the load demands have been considered. The feasibility of the proposed method has been tested on two different balanced radial distribution

Biswarup Das

2009-01-01

62

One-dimensional analysis of plane and radial thin film flows including solid-body rotation  

NASA Technical Reports Server (NTRS)

The flow of a thin liquid film with a free surface along a horizontal plate which emanates from a pressurized vessel is examined by integrating the equations of motion across the thin liquid layer and discretizing the integrated equations using finite difference techniques. The effects of 0-g and solid-body rotation will be discussed. The two cases of interest are plane flow and radial flow. In plane flow, the liquid is considered to be flowing along a channel with no change in the width of the channel, whereas in radial flow the liquid spreads out radially over a disk, so that the area changes along the radius. It is desired to determine the height of the liquid film at any location along the plate of disk, so that the heat transfer from the plate or disk can be found. The possibility that the flow could encounter a hydraulic jump is accounted for.

Thomas, S.; Hankey, W.; Faghri, A.; Swanson, T.

1989-01-01

63

Effects of the radial flows on the chemical evolution of the Milky Way disk  

NASA Astrophysics Data System (ADS)

Context. The majority of chemical evolution models assume that the Galactic disk forms by means of infall of gas and divide the disk into several independent rings without exchange of matter between them. However, if gas infall is important, radial gas flows should be taken into account as a dynamical consequence of infall. Aims: We test the effects of radial gas flows on detailed chemical evolution models (one-infall and two-infall) of the Milky Way disk with different prescriptions for the infall law and star formation rate. Methods: We modified the equation of chemical evolution to include radial gas flows according to the method described in Portinari & Chiosi (2000, A&A, 355, 929). Results: We found that with a gas radial inflow of constant speed the metallicity gradient tends to steepen. Taking into account a constant timescale for the infall rate along the Galaxy disk and radial flows with a constant speed, we obtained too flat a gradient, at variance with data, implying that an inside-out formation and/or a variable gas flow speed are required. To explain the observed gradients, the gas flow should increase in modulus with the galactocentric distance, in both the one-infall and two-infall models. However, the inside-out disk formation coupled with a threshold in the gas density (only in the two-infall model) for star formation and/or a variable efficiency of star formation with galactocentric distance can also reproduce the observed gradients without radial flows. Conclusions: We show that the radial flows can be the most important process in reproducing abundance gradients but only with a variable gas speed. Finally, one should consider that uncertainties in the data concerning gradients prevent us from drawing firm conclusions. Future more detailed data will help us to ascertain whether the radial flows are a necessary ingredient in the formation and evolution of the Galactic disk and disks in general.

Spitoni, E.; Matteucci, F.

2011-07-01

64

Numerical model of fluid flow and oxygen transport in a radial-flow microchannel containing hepatocytes.  

PubMed

The incorporation of monolayers of cultured hepatocytes into an extracorporeal perfusion system has become a promising approach for the development of a temporary bioartificial liver (BAL) support system. In this paper we present a numerical investigation of the oxygen tension, shear stress, and pressure drop in a bioreactor for a BAL composed of plasma-perfused chambers containing monolayers of porcine hepatocytes. The chambers consist of microfabricated parallel disks with center-to-edge radial flow. The oxygen uptake rate (OUR), measured in vitro for porcine hepatocytes, was curve-fitted using Michaelis-Menten kinetics for simulation of the oxygen concentration profile. The effect of different parameters that may influence the oxygen transport inside the chambers, such as the plasma flow rate, the chamber height, the initial oxygen tension in the perfused plasma, the OUR, and K(m) was investigated. We found that both the plasma flow rate and the initial oxygen tension may have an important effect upon oxygen transport. Increasing the flow rate and/or the inlet oxygen tension resulted in improved oxygen transport to cells in the radial-flow microchannels, and allowed significantly greater diameter reactor without oxygen limitation to the hepatocytes. In the range investigated in this paper (10 microns < H < 100 microns), and for a constant plasma flow rate, the chamber height, H, had a negligible effect on the oxygen transport to hepatocytes. On the contrary, it strongly affected the mechanical stress on the cells that is also crucial for the successful design of the BAL reactors. A twofold decrease in chamber height from 50 to 25 microns produced approximately a fivefold increase in maximal shear stress at the inlet of the reactor from 2 to 10 dyn/cm2. Further decrease in chamber height resulted in shear stress values that are physiologically unrealistic. Therefore, the channel height needs to be carefully chosen in a BAL design to avoid deleterious hydrodynamic effects on hepatocytes. PMID:10080090

Ledezma, G A; Folch, A; Bhatia, S N; Balis, U J; Yarmush, M L; Toner, M

1999-02-01

65

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

66

Application of continuation power flow method in radial distribution systems  

Microsoft Academic Search

The paper presents a set of equations (SOE) comprising voltage magnitude and nodal real\\/reactive power balance equations to model a radial distribution system (RDS). The voltage equations in the SOE have dual roots. Then a Newton–Raphson (NR) method is presented to solve the SOE to determine the voltage solution of an RDS. This NR method is extended using the continuation

A. Dukpa; B. Venkatesh; M. El-Hawary

2009-01-01

67

Slip flow in colloidal crystals for ultraefficient chromatography.  

PubMed

Slip flow occurs in colloidal crystals made of 470 nm silica spheres that are chemically modified with hydrocarbon, giving enhanced volume flow rates and a narrower distribution of fluid velocities. Bovine serum albumin separates by pressure-driven flow with a zone that is 15-fold narrower than the theoretical limit for Hagen-Poiseuille flow. The zone variance, normalized for separation length, is 15 nm, which is 500-fold smaller than previous reports for pressure-driven protein chromatography. A colloidal crystal is shown to separate a monoclonal antibody from its aggregates in only 40 s, representing a 10-fold increase in speed. Slip flow, thus, has profound implications for protein chromatography. PMID:22708746

Wei, Bingchuan; Rogers, Benjamin J; Wirth, Mary J

2012-07-01

68

Unsteady flow investigation in rotor-stator interface of a radial diffuser pump  

Microsoft Academic Search

The flow in a vaned diffuser radial pump is fully turbulent and strongly unsteady, caused by the rotor-stator interaction.\\u000a In this paper, two-dimensional laser Doppler velocimetry (LDV) measurement results have been utilized to investigate the unsteady\\u000a flow in a low specific speed radial diffuser pump with leaning impeller trailing edges. CFD simulations have been also conducted\\u000a to provide more extensive

Jianjun Feng; F. K. Benra; H. J. Dohmen

2010-01-01

69

Radial Gas Flows in Colliding Galaxies: Connecting Simulations and Observations  

Microsoft Academic Search

(abridged) We investigate the detailed response of gas to the formation of\\u000atransient and long-lived dynamical structures induced in the early stages of a\\u000adisk-disk collision, and identify observational signatures of radial gas inflow\\u000athrough a detailed examination of the collision simulation of an equal mass\\u000abulge dominated galaxy. Stars respond to the tidal interaction by forming both\\u000atransient arms

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

2004-01-01

70

Radial Gas Flows in Colliding Galaxies: Connecting Simulations and Observations  

Microsoft Academic Search

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

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

2004-01-01

71

Modeling and editing flows using advected radial basis functions  

Microsoft Academic Search

Fluid simulations are notoriously difficult to predict and control. As a result, authoring fluid flows often involves a tedious trial and error process. There is to date no convenient way of editing a fluid after it has been simulated. In particular, the Eulerian approach to fluid simulation is not suitable for flow editing since it does not provide a convenient

Frédéric Pighin; Jonathan M. Cohen; Maurya Shah

2004-01-01

72

A Integrated Power Flow Algorithm for Radial Distribution System with DGs Based on Voltage Regulating  

Microsoft Academic Search

It proposes a promising power flow analysis method for radial distribution system with distributed generations (DGs), combined with reactive power compensation facilities. In the power flow analysis, suitable models are determined for different DG units, Q-sources including Static Var Compensator, Switched Capacitor or Shunt Capacitor and Step Voltage Regulator. A helpful method is presented to deal with the PV node,

Liu Qingzhen; Cai Jinding

2010-01-01

73

An effective topological and primitive impedance based three phase load flow method for radial distribution systems  

Microsoft Academic Search

In this paper, an effective topological primitive impedance based three-phase distribution power flow algorithm is developed. This method fully exploits the radial structure of the network and solves the distribution load flow directly. An effective data structure is proposed to identify all those lines that are incident to the path between the feeding bus and any selected bus. Using this

K. Prakash; M. Sydulu

2008-01-01

74

A novel and fast three-phase load flow for unbalanced radial distribution systems  

Microsoft Academic Search

A novel and fast three-phase load flow algorithm for unbalanced radial distribution systems is proposed in this paper. The proposed method uses branch voltages as state variables and employs the Newton-Raphson (NR) algorithm to solve the load flow problem. By utilizing branch voltages as state variables, a constant Jacobian matrix can be obtained, and a building algorithm for Jacobian matrix

Jen-Hao Teng; Chuo-Yean Chang

2002-01-01

75

A Novel and Fast Three-Phase Load Flow for Unbalanced Radial Distribution Systems  

Microsoft Academic Search

A novel and fast three-phase load flow algorithm for unbalanced radial distribution systems is proposed in this paper. The proposed method uses branch voltages as state variables and employs the Newton-Raphson algorithm to solve the load flow problem. By utilizing branch voltages as state variables, a constant Jacobian matrix can be obtained and a building algorithm for Jacobian matrix is

J. H. Teng; C. Y. Chang

2002-01-01

76

New Load Flow Method SE Oriented For Large Radial Distribution Networks  

Microsoft Academic Search

There is a growing interest in the electric utilities to raise their efficiency in the operation and design of transmission and distribution of systems. This work proposes a new, fast, robust and efficient method for the load flow solution, in balanced and unbalanced radial distribution systems. It is about a sequential method, based on the S-E load flow algorithm devised

H. M. Khodr; L. Ocque; J. M. Yusta; M. A. Rosa

2006-01-01

77

An Efficient Load Flow Solution for Radial Distribution Network Including Voltage Dependent Load Models  

Microsoft Academic Search

An efficient load flow solution is required for automated distribution network for operation and control, and for planning and optimization. This article presents a novel load flow algorithm for solving radial distribution systems. It solves simple algebraic recursive equation of receiving end voltage. In this algorithm, different static load models have been included as the loads are voltage dependent in

S. Satyanarayana; T. Ramana; S. Sivanagaraju; G. K. Rao

2007-01-01

78

An effective topological and primitive impedance based distribution load flow method for radial distribution systems  

Microsoft Academic Search

In this paper, an effective topological primitive impedance and distribution power flow algorithm is developed. This method fully exploits the radial structure of the network and solves the distribution load flow directly. An effective data structure is proposed to identify all those lines that are incident to the path between the feeding bus and any selected bus. Using this concept

K. Prakash; M. Sydulu

2008-01-01

79

Electrocatalytic hydrogenation of soybean oil in a radial flow-through Raney nickel powder reactor  

Microsoft Academic Search

Soybean oil has been hydrogenated electrocatalytically on Raney nickel powder catalyst at atmospheric pressure and moderate temperatures in a novel undivided packed bed radial flow-through reactor. The reactor consisted of a single anode\\/cathode tubular element, where Raney nickel catalyst powder was contained in the annular space between two concentric porous ceramic tubes and the flow of the reaction medium (a

G. Yusem; P. N. Pintauro; P.-C. Cheng; W. An

1996-01-01

80

Non-iterative radial network power flow with parameter uncertainties: Interval mathematics  

Microsoft Academic Search

This paper presents a methodology to solve radial distribution networks load flow problem, wherein the input data are uncertain due to measurement errors. In order to deal with these here the uncertainties, interval mathematics (IM) tool has been applied to obtain the interval load flow solution. The data arrangement to account for uncertainties, the complex load currents at the buses

D. Pawar; C. Radhakrishna; H. S. Jain; S. Ravichander

2009-01-01

81

Radial solids flow structure in a liquid–solids circulating fluidized bed  

Microsoft Academic Search

Radial flow structure was studied using a fiber-optical probe in a 7.6cm ID and 3.0m high liquid–solids circulating fluidized bed (LSCFB). Radial solids holdup profiles were obtained at four different heights for glass beads and plastic beads of mean diameters 508 and 526?m, respectively. The results show that local suspension densities are greater near the wall than in the center

Ying Zheng; Jing-Xu Zhu; Narenderpal S Marwaha; Amarjeet S Bassi

2002-01-01

82

Three Phase Probabilistic Load Flow in Radial Distribution Networks.  

National Technical Information Service (NTIS)

Probabilistic load flow is a helpful tool in accounting for inconsistent or unknown loads and generation. This is especially true with the push for renewable generation and demand response. This paper proposes an improved version of the probabilistic load...

A. Dimitrovski A. C. Melhorn K. Tomsovic

2013-01-01

83

Analysis of the cross flow in a radial inflow turbine scroll  

NASA Technical Reports Server (NTRS)

Equations of motion were derived, and a computational procedure is presented, for determining the nonviscous flow characteristics in the cross-sectional planes of a curved channel due to continuous mass discharge or mass addition. An analysis was applied to the radial inflow turbine scroll to study the effects of scroll geometry and the through flow velocity profile on the flow behavior. The computed flow velocity component in the scroll cross-sectional plane, together with the through flow velocity profile which can be determined in a separate analysis, provide a complete description of the three dimensional flow in the scroll.

Hamed, A.; Abdallah, S.; Tabakoff, W.

1977-01-01

84

Transient radial flow to a well in an unconfined aquifer  

SciTech Connect

The analytic solutions of Boulton (1954) and Neuman (1972) for transient flow to a well in an unconfined aquifer are based on the assumption that the role of the unsaturated zone can be adequately accounted for by restricting attention to the release of water from the zone through which the water table moves. Both researchers mathematically treat this released water as a time-dependent source term. The differences between the models of Boulton and Neuman are that the former neglects vertical components of flow in the aquifer, but allows for an exponential process for the release of water as a function of time, whereas the latter assumes instantaneous release from storage, but accounts for vertical components of flow. Given this set of assumptions, we examine the applicability of these two methods using a general purpose numerical model through a process of verification extension and comparison. The issues addressed include: the role of well-bore storage in masking intermediate-time behavior, combined effects of exponential release as well as vertical flow, logic for vertical averaging of drawdowns, and the sensitivity of system response to the magnitude of specific yield. The issue of how good the assumptions of Boulton and Neuman are in the context of the general theory of unsaturated flow is addressed in part 2 of this two-part series of reports.

Narasimhan, T.N.; Zhu, Ming.

1991-08-01

85

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

86

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

87

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

88

New micro-flow pumping system for liquid chromatography.  

PubMed

This paper deals with the development of practical approaches to a new liquid-delivery system for capillary liquid chromatography. Under different chromatographic conditions, the factors affecting liquid-delivery performance are theoretically described, and the new liquid-delivery system without any splitter is evaluated with its flow-rate accuracy and precision using a variety of solvents. The experimental results demonstrate that the liquid-delivery system is capable of generating accurate, reproducible and conditions-independent micro- and nano-flows. PMID:11355810

Zhou, X; Furushima, N; Terashima, C; Tanaka, H; Kurano, M

2001-04-13

89

Three-phase load flow methods for radial distribution networks  

Microsoft Academic Search

A distribution system has certain distinguishing features which make it different and somewhat difficult to analyze as compared to a transmission system. Unbalanced loads, untransposed lines, single-phase and two-phase laterals are some of them. The distribution system needs to be analyzed on the three-phase basis instead of the single-phase basis. Hence, the three-phase load flow for the distribution system is

A. G. Bhutad; S. V. Kulkarni; S. A. Khaparde

2003-01-01

90

Radial Flow of Pressured Hot Water Through Narrow Cracks  

SciTech Connect

Geothermal wells discharging hundreds of tons/hour of steam-water mixtures may be supplied at depth from one very narrow crack of width 1 to 2 mm, or alternatively, from some hundreds of hairline cracks. In the former case, turbulent flow takes place out to tens of meters from the well while the sum of frictional and kinetic pressure-drop indicates the flashing distance to be of the order of 10 cm from the well wall for pressure-temperature equilibrium. However it is unlikely that equilibrium obtains because of the high water velocity (order of 100 m/s) near the well giving no time for bubble nucleation. Flashing and hence mineral deposition are therefore not at all likely in the crack but can occur within the well from the crack horizon upwards. In the case of a multitude of fine cracks giving the same total flow, streamline conditions prevail over the flow path with the flash front a meter or so from the well, hence deposition is a possibility.

James, Russell

1983-12-15

91

Radial, mixed and axial-flow pumps: Introduction, amendment A  

NASA Astrophysics Data System (ADS)

This Data Item is available as part of the ESDU Sub-series on Fluid Mechanics Internal Flow. Background information intended to guide the nonspecialist in the selection of an appropriate type of pump, for writing its specification, and for the appraisal of tenders is provided. Sections on pump performance characteristics, illustrations of typical configurations, features of national and international standards on pumps and on calculation of system requirements are included. An extensive section on matching the pump to the system includes guidance on multipump operation and on waterhammer calculations.

1981-02-01

92

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.

Bonini, Romulo 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

93

One-Dimensional Analysis of a Radial Source Flow of Water Particles into a Vacuum.  

National Technical Information Service (NTIS)

An analytical investigation is made of a one-dimensional radial source flow of water into a vacuum. The equations that describe this model are a sixth-order, nonlinear, two-point boundary value problem. The problem is solved by the shooting/splitting tech...

A. Setayesh

1990-01-01

94

An Improved Backward\\/Forward Sweep Load Flow Algorithm for Radial Distribution Systems  

Microsoft Academic Search

This letter presents an improved backward\\/ forward sweep algorithm for three-phase load-flow analysis of radial distribution systems. In the backward sweep, Kirchhoff's Current Law and Kirchhoff's Voltage Law are used to calculate the upstream bus voltage of each line or a transformer branch. Then, the linear proportional principle is adopted to find the ratios of the real and imaginary components

G. W. Chang; S. Y. Chu; H. L. Wang

2007-01-01

95

Loop frame of reference based three-phase power flow for unbalanced radial distribution systems  

Microsoft Academic Search

This paper introduces a novel three-phase power flow approach for unbalanced radial distribution systems. The proposed approach is developed based on the loop frame of reference, rather than the traditional bus frame of reference. On the basis of the loop frame of reference, a simple direct iterative method in impedance form is applied. Basic graph theory and injection current technique

Tsai-Hsiang Chen; Nien-Che Yang

2010-01-01

96

A new power flow method for radial distribution systems including voltage dependent load models  

Microsoft Academic Search

This paper presents a simple and efficient method to solve the power flow problem in radial distribution systems. The proposed method takes into account voltage dependency of static loads, and line charging capacitance. The method is based on the forward and backward voltage updating by using polynomial voltage equation for each branch and backward ladder equation (Kirchoff's Laws). Convergence ability

Ulas Eminoglu; M. Hakan Hocaoglu

2005-01-01

97

Fuzzy load flow in balanced and unbalanced radial distribution systems incorporating composite load model  

Microsoft Academic Search

This paper presents a fuzzy approach load flow for balanced and unbalanced radial distribution systems with incorporating load model. Fuzzy set theory proposes an appropriate way to model inexactly expressed information and data which have uncertainty. In this paper the combination of fuzzy models and techniques for electrical distribution systems is presented. The theories relating to the fuzzy numbers are

Belal Mohammadi Kalesar; Ali Reza Seifi

2010-01-01

98

Symmetric radial laminar channel flow with particular reference to aerostatic bearings  

Microsoft Academic Search

After a short survey of the different methods and formulas used to determine the pressure distribution in radial (converging or diverging) flow between nominally parallel disks, the method of separation of variables is applied to the problem, especially the case pertaining to centrally fed circular aerostatic bearings. The results are compared extensively with experimental data from various sources, and the

F. Al-Bender; H. van Brussel

1992-01-01

99

A simplified approach for load flow analysis of radial distribution network with embedded generation  

Microsoft Academic Search

This paper presents a simple approach for load flow analysis of a radial distribution network with embedded generation. The proposed approach utilizes forward and backward sweep algorithm based on Kirchoffpsilas current law (KCL) and Kirchoffpsilas voltage law (KVL) for evaluating the node voltages iteratively. In this approach, computation of branch current depends only on the current injected at the neighbouring

K Vinoth Kumar; M. P. Selvan

2008-01-01

100

Simple and efficient method for load flow solution of radial distribution networks  

Microsoft Academic Search

The paper presents a simple and efficient method for solving radial distribution networks. The proposed method involves only the evaluation of a simple algebraic expression of voltage magnitudes and no trigonometric functions as opposed to the standard load flow case. Thus, computationally the proposed method is very efficient and it requires less computer memory. The proposed method can easily handle

A. Kalam

1995-01-01

101

A Simplified Approach for Load Flow Analysis of Radial Distribution Network  

Microsoft Academic Search

This paper presents a simple approach for load flow analysis of a radial distribution network. The proposed approach utilizes forward and backward sweep algorithm based on Kirchoff's current law (KCL) and Kirchoff's voltage law (KVL) for evaluating the node voltages iteratively. In this approach, computation of branch current depends only on the current injected at the neighbouring node and the

K. Vinoth Kumar; M. P. Selvan

2008-01-01

102

Extension of the modified Newton method for radial distribution systems load flow  

Microsoft Academic Search

In this paper we develop and compare two different methods, based on the branch-oriented techniques, for the resolution of load flow in radial distribution systems. The former is the current summation method and the later is the modified Newton method. The extension of these methods is that the load shall be represented with its variation with respect to the voltage

S. Kebaili; F. Adjeroud; K. Zehar

2001-01-01

103

Origins of Radial Fracture Systems and Associated Large Lava Flows on Venus.  

National Technical Information Service (NTIS)

Magellan images have revealed the existence of systems of radial fractures on venus that are very similar in form to terrestrial dike swarms such as the Mackenzie swarm in Northern Canada. The association of many of the fracture systems with lava flows, c...

E. A. Parfitt, L. Wilson, J. W. Head

1992-01-01

104

Modeling of transient flow through a viscoelastic preparative chromatography packing.  

PubMed

The common method for purification of macromolecular bioproducts is preparative packed-bed chromatography using polymer-based, compressible, viscoelastic resins. Due to a downstream processing bottleneck, the chromatography equipment is often operated at its hydrodynamic limit. In this case, the resins may exhibit a complex behavior which results in compression-relaxation hystereses. Up to now, no modeling approach of transient flow through a chromatography packing has been made considering the viscoelasticity of the resins. The aim of the present work was to develop a novel model and compare model calculations with experimental data of two agarose-based resins. Fluid flow and bed permeability were modeled by Darcy's law and the Kozeny-Carman equation, respectively. Fluid flow was coupled to solid matrix stress via an axial force balance and a continuity equation of a deformable packing. Viscoelasticity was considered according to a Kelvin-Voigt material. The coupled equations were solved with a finite difference scheme using a deformable mesh. The model boundary conditions were preset transient pressure drop functions which resemble simulated load-/elution-/equilibration cycles. Calculations using a homogeneous model (assuming constant variables along the column height) gave a fair agreement with experimental data with regard to predicted flow rate, bed height, and compression-relaxation hysteresis for symmetric as well as asymmetric pressure drop functions. Calculations using an inhomogeneous model gave profiles of the bed porosity as a function of the bed height. In addition, the influence of medium wall support and intra-particle porosity was illustrated. The inhomogeneous model provides insights that so far are not easily experimentally accessible. © 2013 American Institute of Chemical Engineers Biotechnol. Prog.,, 2013. PMID:23757198

Hekmat, Dariusch; Kuhn, Michael; Meinhardt, Verena; Weuster-Botz, Dirk

2013-06-11

105

Modeling of transient flow through a viscoelastic preparative chromatography packing.  

PubMed

The common method for purification of macromolecular bioproducts is preparative packed-bed chromatography using polymer-based, compressible, viscoelastic resins. Because of a downstream processing bottleneck, the chromatography equipment is often operated at its hydrodynamic limit. In this case, the resins may exhibit a complex behavior which results in compression-relaxation hystereses. Up to now, no modeling approach of transient flow through a chromatography packing has been made considering the viscoelasticity of the resins. The aim of the present work was to develop a novel model and compare model calculations with experimental data of two agarose-based resins. Fluid flow and bed permeability were modeled by Darcy's law and the Kozeny-Carman equation, respectively. Fluid flow was coupled to solid matrix stress via an axial force balance and a continuity equation of a deformable packing. Viscoelasticity was considered according to a Kelvin-Voigt material. The coupled equations were solved with a finite difference scheme using a deformable mesh. The model boundary conditions were preset transient pressure drop functions which resemble simulated load/elution/equilibration cycles. Calculations using a homogeneous model (assuming constant variables along the column height) gave a fair agreement with experimental data with regard to predicted flow rate, bed height, and compression-relaxation hysteresis for symmetric as well as asymmetric pressure drop functions. Calculations using an inhomogeneous model gave profiles of the bed porosity as a function of the bed height. In addition, the influence of medium wall support and intraparticle porosity was illustrated. The inhomogeneous model provides insights that so far are not easily experimentally accessible. PMID:23798499

Hekmat, Dariusch; Kuhn, Michael; Meinhardt, Verena; Weuster-Botz, Dirk

2013-01-01

106

Computer simulations and measurements of radial solid flow distribution in a riser  

NASA Astrophysics Data System (ADS)

Comparisons between the numerical predictions from a two-phase model and the experimental hydrodynamic data have been performed in fully developed gas-solid flows for FCC catalysts. The results suggested the existence of self-similar solid flux profiles at low solid fluxes. Non-uniformity in the radial solids fluxes was found with a high solid flowing mainly downward near the wall. The model predictions were reasonably caught up the experimental trends.

Lu, Huilin; Zhao, Gangbo; Yang, Lidan; Liu, Wenti

1998-06-01

107

A Novel Method for Load Flow Analysis of Unbalanced Three-Phase Radial Distribution Networks  

Microsoft Academic Search

This paper presents a novel method for load flow analysis in radially operated 3-phase distribution networks without solving the well-known conventional load flow equations. The method can be applied for distribution systems in which the loads are unbalanced. As the size of matrix used is very small compared to those in conventional methods,the amount of memory used is very small,the

Masoud Aliakbar GOLKAR

2007-01-01

108

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.

109

Measurement and Modeling of the Flows and Radial Electric Field in the HSX Stellarator  

NASA Astrophysics Data System (ADS)

A charge exchange recombination spectroscopy (CHERS) diagnostic was developed and used to measure the C+6 velocity, temperature and density in the HSX stellarator. These measurements were used to determine the radial electric field (Er) and parallel flow velocities which were compared to neoclassical calculations. Neoclassical calculations of E r and parallel flow velocities in stellarators are typically performed using a simplified non-momentum conserving collision operator, but these calculations were found to under predict the parallel flow velocity in HSX by approximately an order of magnitude. The inclusion of momentum conservation in the PENTA code improved the agreement between the measured and calculated total plasma flow direction, which approximately follows the helical direction of symmetry in HSX. However, discrepancies were seen between the measured and calculated Er and parallel flow profiles. In the core, the parallel flows were measured to reach speeds of up to 20 km/s in the optimized quasi-helically symmetric (QHS) magnetic configuration, but these measured values were slower than the values calculated by PENTA in that region. For the Mirror magnetic configuration, in which the symmetry of the magnetic field is intentionally broken, the calculated parallel flow was smaller than the flow calculated for the QHS configuration but was still larger than the measured flow. The measured radial electric field was about 2 kV/m across the plasma. The radial electric field calculations had multiple solutions, or roots, in the core of HSX plasmas. The measured Er was found to be much lower than the large, 30 kV/m, electron root value which was calculated by PENTA. Better agreement was seen between the measured Er and the smaller ion root value calculated for much of the plasma. No measureable change in the parallel flow was seen when the plasma density was varied within the operationally achievable range. A significant increase in the measured parallel flow was seen with increased electron heating.

Briesemeister, Alexis R.

110

Insights from theory and experiments on slip flow in chromatography  

PubMed Central

Slip flow has become a topic of interest in reversed-phase liquid chromatography because it gives a flow enhancement that facilitates the use of submicrometer particles, providing a large improvement in separation efficiency. Moreover, slip flow provides an additional improvement in efficiency by reducing the velocity distribution in the mobile phase. The phenomenon of slip flow in open tubes is described in chromatographically relative terms. A recent paper in this journal is discussed, as it provides the first theoretical study of slip flow in packed beds, in this case for face-centered cubic geometry. The theory paper reveals that the presence of the packed bed introduces a heterogeneity in fluid velocities that is absent in open tubes, reducing the additional improvement in efficiency from slip flow. The recent paper also suggests that there is yet another factor improving efficiency, which is size-exclusion of proteins from regions of stagnant flow. The latter is supported by recently published data on restricted protein diffusion in face-centered cubic silica colloidal crystals. Extremely low plate heights are enabled by use of submicrometer particles, and further improvement appears to be possible when the analyte size is on the order of 1% of the particle diameter or larger.

Wu, Zhen; Rogers, Benjamin J.; Wei, Bingchuan; Wirth, Mary J.

2014-01-01

111

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

112

Turbulence-driven zonal flows in helical systems with radial electric fields  

SciTech Connect

Collisionless long-time responses of the zonal-flow potential to the initial condition and turbulence source in helical systems having radial electric fields are derived theoretically. All classes of particles in passing, toroidally trapped, and helical-ripple-trapped states are considered. The transitions between the toroidally trapped and helical-ripple-trapped states are taken into account while solving the gyrokinetic equation analytically by taking its average along the particle orbits. When the radial displacements of helical-ripple-trapped particles are reduced either by neoclassical optimization of the helical geometry lowering the radial drift or by strengthening the radial electric field E{sub r} to boost the poloidal rotation, enhanced zonal-flow responses are obtained. Under the identical conditions on the magnitude of E{sub r} and the magnetic geometry, using ions with a heavier mass gives rise to a higher zonal-flow response, and therefore the turbulent transport is expected to show a more favorable ion-mass dependence than the conventional gyro-Bohm scaling.

Sugama, H.; Watanabe, T.-H. [National Institute for Fusion Science, Toki 509-5292, Japan and The Graduate University for Advanced Studies, Toki 509-5292 (Japan)

2009-05-15

113

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

114

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

115

Recent advances in flow-controlled multidimensional gas chromatography.  

PubMed

The continued development of flow-controlled two-dimensional gas chromatography (2-D GC) is reviewed, with a special emphasis on results published from 2001 through 2011. Heart-cutting 2-D GC continues to be used for isolating selected components in complex mixtures. The programmable and highly precise flows and temperatures produced by modern gas chromatographs have made it easier to selectively transfer analytes to the secondary column and to backflush unwanted components from the primary column. Several new Deans switch interfaces for performing heart-cutting 2-D GC have been introduced, with most attention given to devices that integrate the flow connections into a single unit. Heart-cutting 2-D GC has been used to isolate analytes in a wide variety of complex mixtures including fuels, industrial feedstocks, fragrances, and environmental extracts. Valve-based comprehensive 2-D GC (GC×GC) was also actively developed in the past decade. Valve-based modulation is a simple way to generate GC×GC separations without using cryogenic fluids. More than ten new valve-based modulators were introduced. Diaphragm valves fitted with sample loops are the most common low duty cycle modulators, whereas fluidic modulators that employ differential flow conditions are the most common high duty cycle modulators. Applications of valve-based GC×GC include analysis of hydrocarbon mixtures, essential oils, and environmental samples. PMID:22305357

Seeley, John V

2012-09-14

116

Heat transfer enhancement and pumping power in confined radial flows using nanoparticle suspensions (nanofluids)  

Microsoft Academic Search

This paper presents a numerical investigation of heat transfer enhancement capabilities of coolants with suspended nanoparticles (Al2O3 dispersed in water) inside a confined impinging jet cooling device. Steady, laminar radial flow of a nanofluid in a axis-symmetric configuration with axial coolant injection has been considered. A single phase fluid approach was adopted to numerically investigate the behavior of nanofluids in

Iulian Gherasim; Gilles Roy; Cong Tam Nguyen; Dinh Vo-Ngoc

2011-01-01

117

Time-related capture zones for radial flow in two dimensional randomly heterogeneous media  

Microsoft Academic Search

.   We consider the effect of randomly heterogeneous hydraulic conductivity on the spatial location of time-related capture zones\\u000a (isochrones) for a non-reactive tracer in the steady-state radial flow field due to a pumping well in a confined aquifer.\\u000a A Monte Carlo (MC) procedure is used in conjunction with FFT-based spectral methods. The log hydraulic conductivity field\\u000a is assumed to be

M. Riva; A. Guadagnini; F. Ballio

1999-01-01

118

Modeling of TIG welding and abrasive flow machining processes using radial basis function networks  

Microsoft Academic Search

Input-output relationships of tungsten inert gas (TIG) welding and abrasive flow machining (AFM) processes were determined\\u000a using radial basis function networks (RBFNs). A batch mode of training was adopted to implement the principle of back-propagation\\u000a (BP) algorithm (which works based on a steepest descent algorithm) and a genetic algorithm (GA), separately. The performances\\u000a of RBFN tuned by a BP algorithm

Asfak Ali Mollah; Dilip Kumar Pratihar

2008-01-01

119

Numerical investigation of laminar flow and heat transfer in a radial flow cooling system with the use of nanofluids  

Microsoft Academic Search

Nanofluids, because of their enhanced heat transfer capability as compared to normal water\\/glycol\\/oil based fluids, offer the engineer opportunities for development in areas where high heat transfer, low temperature tolerance and small component size are required. In this present paper, the hydrodynamic and thermal fields of a water–?Al2O3 nanofluid in a radial laminar flow cooling system are considered. Results indicate

Gilles Roy; Cong Tam Nguyen; Paul-René Lajoie

2004-01-01

120

Understanding IMF Bz and Space Weather Relations Near Geomagnetic Equator Related to Non-Radial Solar Wind Flows (P35)  

NASA Astrophysics Data System (ADS)

We have reported earlier some new results related to the seasonal and solar cycle changes in the north-south component of IMF (Bz) observed near 1 A.U. A relationship between geomagnetic activity and non-radial solar wind flows were reported recently. In this connection, we are planning some studies for IHY 2007. We propose to identify non-radial flow structures in the interplanetary medium using IPS observations and predict the associated IMF Bz structures. The effect of geomagnetic storms near magnetic equator associated with non-radial solar wind flows will be studied using magnetometer observations in Trivandrum.

Pereira, F.; Girish, T. E.

2006-11-01

121

Porcine circovirus (PCV) removal by Q sepharose fast flow chromatography.  

PubMed

The recently discovered contamination of oral rotavirus vaccines led to exposure of millions of infants to porcine circovirus (PCV). PCV was not detected by conventional virus screening tests. Regulatory agencies expect exclusion of adventitious viruses from biological products. Therefore, methods for inactivation/removal of viruses have to be implemented as an additional safety barrier whenever feasible. However, inactivation or removal of PCV is difficult. PCV is highly resistant to widely used physicochemical inactivation procedures. Circoviruses such as PCV are the smallest viruses known and are not expected to be effectively removed by currently-used virus filters due to the small size of the circovirus particles. Anion exchange chromatography such as Q Sepharose(®) Fast Flow (QSFF) has been shown to effectively remove a range of viruses including parvoviruses. In this study, we investigated PCV1 removal by virus filtration and by QSFF chromatography. As expected, PCV1 could not be effectively removed by virus filtration. However, PCV1 could be effectively removed by QSFF as used during the purification of monoclonal antibodies (mAbs) and a log10 reduction value (LRV) of 4.12 was obtained. PMID:24039195

Yang, Bin; Wang, Hua; Ho, Cintia; Lester, Philip; Chen, Qi; Neske, Florian; Baylis, Sally A; Blümel, Johannes

2013-01-01

122

Radial and vertical flows induced by galactic spiral arms: likely contributors to our `wobbly Galaxy'  

NASA Astrophysics Data System (ADS)

In an equilibrium axisymmetric galactic disc, the mean Galactocentric radial and vertical velocities are expected to be zero everywhere. In recent years, various large spectroscopic surveys have however shown that stars of the Milky Way disc exhibit non-zero mean velocities outside of the Galactic plane in both the Galactocentric radial and vertical velocity components. While radial velocity structures are commonly assumed to be associated with non-axisymmetric components of the potential such as spiral arms or bars, non-zero vertical velocity structures are usually attributed to excitations by external sources such as a passing satellite galaxy or a small dark matter substructure crossing the Galactic disc. Here, we use a three-dimensional test-particle simulation to show that the global stellar response to a spiral perturbation induces both a radial velocity flow and non-zero vertical motions. The resulting structure of the mean velocity field is qualitatively similar to what is observed across the Milky Way disc. We show that such a pattern also naturally emerges from an analytic toy model based on linearized Euler equations. We conclude that an external perturbation of the disc might not be a requirement to explain all of the observed structures in the vertical velocity of stars across the Galactic disc. Non-axisymmetric internal perturbations can also be the source of the observed mean velocity patterns.

Faure, Carole; Siebert, Arnaud; Famaey, Benoit

2014-05-01

123

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

124

Comparison of the flows and radial electric field in the HSX stellarator to neoclassical calculations  

NASA Astrophysics Data System (ADS)

Intrinsic flow velocities of up to ˜20 km s-1 have been measured using charge exchange recombination spectroscopy (CHERS) in the quasi-helically symmetric HSX stellarator and are compared with the neoclassical values calculated using an updated version (Lore 2010 Measurement and Transport Modeling with Momentum Conservation of an Electron Internal Transport Barrier in HSX (Madison, WI: University of Wisconsin); Lore et al 2010 Phys. Plasmas 17 056101) of the PENTA code (Spong 2005 Phys. Plasmas. 12 056114). PENTA uses the monoenergetic transport coefficients calculated by the drift kinetic equation solver code (Hirshman et al 1986 Phys. Fluids 29 2951; van Rij and Hirshman 1989 Phys. Fluids B 1 563), but corrects for momentum conservation. In the outer half of the plasma good agreement is seen between the measured parallel flow profile and the calculated neoclassical values when momentum correction is included. The flow velocity in HSX is underpredicted by an order of magnitude when this momentum correction is not applied. The parallel flow is calculated to be approximately equal for the majority hydrogen ions and the C6+ ions used for the CHERS measurements. The pressure gradient of the protons is the primary drive of the calculated parallel flow for a significant portion of the outer half of the plasma. The values of the radial electric field calculated with and without momentum correction were similar, but both were smaller than the measured values in the outer half of the plasma. Differences between the measured and predicted radial electric field are possibly a result of uncertainty in the composition of the ion population and sensitivity of the ion flux calculation to resonances in the radial electric field.

Briesemeister, A.; Zhai, K.; Anderson, D. T.; Anderson, F. S. B.; Talmadge, J. N.

2013-01-01

125

A Power Flow Method for Radial and Meshed Distribution Systems Including Distributed Generation and Step Voltage Regulator Modeling  

Microsoft Academic Search

This paper proposes a new power flow method for radial and meshed distribution systems. The method convert a meshed distribution system with distributed generators into an equivalent single source radial distribution system, by breaking out the tie lines and distributed generators con- nections, and by abstracting auxiliary buses to the distri- bution network. The approach goes beyond the previous works

Diego Issicaba; J. Coelho

2007-01-01

126

A radial flow hollow fiber bioreactor for the large-scale culture of mammalian cells.  

PubMed

A radial flow hollow fiber bioreactor has been developed that maximizes the utilization of fiber surface for cell growth while eliminating nutrient and metabolic gradients inherent in conventional hollow fiber cartridges. The reactor consists of a central flow distributor tube surrounded by an annular bed of hollow fibers. The central flow distributor tube ensures an axially uniform radial convective flow of nutrients across the fiber bed. Cells attach and proliferate on the outer surface of the fibers. The fibers are pretreated with polylysine to facilitate cell attachment and long-term maintenance of tissuelike densities of cell mass. A mixture of air and CO(2) is fed through the tube side of the hollow fibers, ensuring direct oxygenation of the cells and maintenance of pH. Spent medium diffuses across the cell layer into the tube side of the fibers and is convected away along with the spent gas stream. The bioreactor was run as a recycle reactor to permit maximum utilization of nutrient medium. A bioreactor with a membrane surface area of 1150 cm(2) was developed and H1 cells were grown to a density of 7.3 x 10(6) cells/cm(2). PMID:18555333

Tharakan, J P; Chau, P C

1986-03-01

127

On the nature of radial transport across sheared zonal flows in electrostatic ion-temperature-gradient gyrokinetic tokamak plasma turbulence  

SciTech Connect

It is argued that the usual understanding of the suppression of radial turbulent transport across a sheared zonal flow based on a reduction in effective transport coefficients is, by itself, incomplete. By means of toroidal gyrokinetic simulations of electrostatic, ion-temperature-gradient turbulence, it is found instead that the character of the radial transport is altered fundamentally by the presence of a sheared zonal flow, changing from diffusive to anticorrelated and subdiffusive. Furthermore, if the flows are self-consistently driven by the turbulence via the Reynolds stresses (in contrast to being induced externally), radial transport becomes non-Gaussian as well. These results warrant a reevaluation of the traditional description of radial transport across sheared flows in tokamaks via effective transport coefficients, suggesting that such description is oversimplified and poorly captures the underlying dynamics, which may in turn compromise its predictive capabilities.

Sanchez, R. [Fusion Energy Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States); Newman, D. E. [Department of Physics, University of Alaska, Fairbanks, Alaska 99775-5920 (United States); Leboeuf, J.-N. [JNL Scientific, Inc., Casa Grande, Arizona 85294-9695 (United States); Carreras, B. A. [BACV Solutions, Inc., Oak Ridge, Tennessee 37830-8222 (United States); Decyk, V. K. [UCLA, Los Angeles, California 90095-1547 (United States)

2009-05-15

128

On the nature of radial transport across sheared zonal flows in electrostatic ion-temperature-gradient gyrokinetic tokamak turbulence  

SciTech Connect

It is argued that the usual understanding of the suppression of radial turbulent transport across a sheared zonal flow based on a reduction in effective transport coefficients is, by itself, incomplete. By means of toroidal gyrokinetic simulations of electrostatic, ion-temperature-gradient turbulence, it is found instead that the character of the radial transport is altered fundamentally by the presence of a sheared zonal flow, changing from diffusive to anticorrelated and subdiffusive. Furthermore, if the flows are self-consistently driven by the turbulence via the Reynolds stresses (in contrast to being induced externally), radial transport becomes non-Gaussian as well. These results warrant a reevaluation of the traditional description of radial transport across sheared flows in tokamaks via effective transport coefficients, suggesting that such description is oversimplified and poorly captures the underlying dynamics, which may in turn compromise its predictive capabilities.

Sanchez, Raul [ORNL; Newman, David E [University of Alaska; Leboeuf, Jean-Noel [JNL Scientific, Inc., Casa Grande, AZ; Carreras, Benjamin A [BACV Solutions, Inc., Oak Ridge; Decyk, Viktor [University of California, Los Angeles

2009-01-01

129

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

130

A numerical analysis of turbulent compressible radial channel flow with particular reference to pneumatic controllers  

NASA Astrophysics Data System (ADS)

A numerical analysis of turbulent axisymmetric radial compressible channel flow between a nozzle and a flat plate is presented in this paper. In particular, the application of this type of flow situation in pneumatic dimensional control systems is considered. The Spalart-Allmaras one-equation turbulence model is used. The resulting highly coupled PDE system has been solved using the control volume based numerical approach where the power-law scheme was used extensively to compute the diffusive and convective fluxes of momentum. Results show that local Mach numbers can easily achieve and surpass unity for typical industrial configurations. Also, in the case of a standard industrial nozzle geometry, the presence of a toroïdal recirculation zone that moves radially outward is clearly identified in most cases. Separated flow areas are of particular concern as it has been shown previously that they can cause nozzle fouling in industrial applications. It has been shown that the size of this region is dependant on feed pressure. Considerable differences between results obtained using the Spalart-Allmaras and standard k- ? turbulence models have also been noticed.

Roy, Gilles; Vo-Ngoc, Dinh; Bravine, Vadim

2004-02-01

131

Chromatography  

MedlinePLUS

... high pressure liquid, or ion exchange chromatography. In general, chromatography takes advantage of the differences in the chemicals you want to separate, such as their size, electric charge, or ability to stick to (bind) to ...

132

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.

2011-05-16

133

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

134

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

135

A study of radial-flow turbomachinery blade vibration measurements using Eulerian laser Doppler vibrometry  

NASA Astrophysics Data System (ADS)

The structural integrity of blades is critical to the health of turbomachinery. Since operational failure of these blades can possibly lead to catastrophic failure of the machine, it is important to have knowledge of blade conditions in an online fashion. Due to several practical implications, it is desired to measure blade vibration with a non-contact technique. The application of laser Doppler vibrometry towards the vibration based condition monitoring of axial-flow turbomachinery blades has been successfully demonstrated in previous work. In this paper the feasibility of using laser Doppler vibrometry to measure radial-flow turbomachinery blade vibrations is investigated with the aid of digital image correlation and strain gauge telemetry.

Oberholster, A. J.; Heyns, P. S.

2014-05-01

136

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

137

Small-volume radial flow cell for all-solid-state ion-selective electrodes.  

PubMed

A flow cell with a radial distribution of four all-solid-state ion selective electrodes (ISEs), or alternatively three ISEs and one reference electrode, was designed and optimized for mass production. The radial distribution of the electrodes reduces the cell volume and is expected to minimize cross-contamination between different electrodes. Two different cell prototypes were developed and tested for all-solid-state K(+)-ISEs based on a solvent polymeric ion-selective membrane (ISM) and a conducting polymer, poly(3,4-ethylenedioxythiophene), as solid internal contact. In the first prototype, PEDOT was electropolymerized from an aqueous solution of the monomer and the doping ion salt, sodium polystyrenesulfonate (NaPSS). The second prototype employed an aqueous dispersion of PEDOT(PSS) that is commercially available (Baytron P, Bayer AG). Compared to electrochemical synthesis, solution casting of the polymer dispersion was found to be a more advantageous method to deposit the conducting polymer layer aiming at mass production. The resulting prototypes of the flow cell had a small volume (ca. 17-37mul), which makes them suitable for application in clinical analysis. PMID:18969263

Vázquez, Mercedes; Bobacka, Johan; Ivaska, Ari; Lewenstam, Andrzej

2004-01-01

138

Heat transfer enhancement with the use of nanofluids in radial flow cooling systems considering temperature-dependent properties  

Microsoft Academic Search

Heat transfer enhancement capabilities of coolants with suspended metallic nanoparticles inside typical radial flow cooling systems are numerically investigated in this paper. The laminar forced convection flow of these nanofluids between two coaxial and parallel disks with central axial injection has been considered using temperature dependent nanofluid properties. Results clearly indicate that considerable heat transfer benefits are possible with the

Samy Joseph Palm; Gilles Roy; Cong Tam Nguyen

2006-01-01

139

Analysis of radial distribution systems with embedded series FACTS devices using a fast line flow-based algorithm  

Microsoft Academic Search

Analysis of radial distribution systems with embedded series Flexible AC Transmission System (FACTS) devices is facilitated by a formulation of power flow equations with bus voltage magnitudes and line flows as independent variables. Since control variables such as the line and bus reactive powers figure directly in the formulation, handling the control action of FACTS devices in distribution systems is

Ping Yan; Arun Sekar

2005-01-01

140

Consideration of input parameter uncertainties in load flow solution of three-phase unbalanced radial distribution system  

Microsoft Academic Search

In this paper, a technique based on interval arithmetic is presented for considering the uncertainties of the input parameters in the power flow solution of three-phase unbalanced radial distribution systems. The uncertainties in both the load demand and the feeder parameters have been considered. The results obtained from an interval arithmetic-based power flow solution have been compared with those obtained

Biswarup Das

2006-01-01

141

Load flow solution for ill-condition radial distribution network including static load model and daily load values  

Microsoft Academic Search

In distribution load flow studies, it is presumed that active and reactive power demands are constant at each node regardless of the voltage magnitude and time. In actual distribution system, different categories and types of loads might be present and varies with time. In this paper an efficient load flow technique is developed for ill-condition radial distribution network. This paper

Khyati. D. Mistry; Ranjit. Roy

2011-01-01

142

Measurement of the Md3+/Md2+ reduction potential studied with flow electrolytic chromatography.  

PubMed

The reduction behavior of mendelevium (Md) was studied using a flow electrolytic chromatography apparatus. By application of the appropriate potentials on the chromatography column, the more stable Md(3+) is reduced to Md(2+). The reduction potential of the Md(3+) + e(-) ? Md(2+) couple was determined to be -0.16 ± 0.05 V versus a normal hydrogen electrode. PMID:24116851

Toyoshima, Atsushi; Li, Zijie; Asai, Masato; Sato, Nozomi; Sato, Tetsuya K; Kikuchi, Takahiro; Kaneya, Yusuke; Kitatsuji, Yoshihiro; Tsukada, Kazuaki; Nagame, Yuichiro; Schädel, Matthias; Ooe, Kazuhiro; Kasamatsu, Yoshitaka; Shinohara, Atsushi; Haba, Hiromitsu; Even, Julia

2013-11-01

143

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

144

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

145

Raman scattering of InGaAs/InP grown by uniform radial flow epitaxy  

NASA Technical Reports Server (NTRS)

Uniform radial flow epitaxy, a novel growth technique, has been used to grown InGaAs films on InP. Epitaxial layers above and below the critical thickness for the onset of slip were grown. Raman spectroscopy was used to characterize the quality of epitaxial layers, determine alloy composition, and measure the strain. Raman spectra from both pseudomorphic (strained) and relaxed (unstrained) InGaAs films were obtained at 300 and 80 K. The difference in the frequencies of their GaAs-like longitudinal optical phonons was used to calculate stress for the strained InGaAs/InP, leading to a direct formula for the evaluation of the layer stress.

Feng, Z. C.; Allerman, A. A.; Barnes, P. A.; Perkowitz, S.

1992-01-01

146

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

147

Performance back-deduction from a loading to flow coefficient map: Application to radial turbine  

NASA Astrophysics Data System (ADS)

Radial turbine stages are often used for applications requiring off-design operation, as turbocharging for instance. The off-design ability of such stages is commonly analyzed through the traditional turbine map, plotting the reduced mass-flow against the pressure-ratio, for reduced-speed lines. However, some alternatives are possible, such as the flow-coefficient ( ?) to loading-coefficient ( ?) diagram where the pressure-ratio lines are actually straight lines, very convenient property to perform prediction. A robust method re-creating this map from a predicted ?-? diagram is needed. Recent work has shown that this back-deduction quality, without the use of any loss models, depends on the knowledge of an intermediate pressure-ratio. A modelization of this parameter is then proposed. The comparison with both experimental and CFD results is presented, with quite good agreement for mass flow rate and rotational speed, and for the intermediate pressure ratio. The last part of the paper is dedicated to the application of the intermediate pressure-ratio knowledge to the improvement of the deduction of the pressure ratio lines in the ?-? diagram. Beside this improvement, the back-deduction method of the classical map is structured, applied and evaluated.

Carbonneau, Xavier; Binder, Nicolas

2012-12-01

148

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

PubMed

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: the missing fundamental (mf) stimulus. The radial motion consisted of successive 1/4-wavelength steps, so that the overall pattern and the 4n+1 harmonics (where n=integer) underwent radial expansion (or contraction), whereas the 4n-1 harmonics--including the strongest Fourier component (the 3rd harmonic)--underwent the opposite radial motion. Radial motion commenced only after the subject had fixated the center of the pattern. The initial RFVRs were always in the direction of the 3rd harmonic, e.g., expansion of the mf pattern causing divergence. Thus, the earliest RFVRs were strongly dependent on the motion of the major Fourier component, consistent with early spatio-temporal filtering prior to motion detection, as in the well-known energy model of motion analysis. If the radial mf stimulus was reduced to just two competing harmonics--the 3rd and 5th--the initial RFVRs showed a nonlinear dependence on their relative contrasts: when the two harmonics differed in contrast by more than about an octave then the one with the higher contrast completely dominated the RFVRs and the one with lower contrast lost its influence: winner-take-all. We suggest that these nonlinear interactions result from mutual inhibition between the mechanisms sensing the motion of the different competing harmonics. If single radial-flow steps were used, a brief inter-stimulus interval resulted in reversed RFVRs, consistent with the idea that the motion detectors mediating these responses receive a visual input whose temporal impulse response function is strongly biphasic. Lastly, all of these characteristics of the RFVR, which we attribute to the early cortical processing of visual motion, are known to be shared by the Ocular Following Response (OFR)--a conjugate tracking (version) response elicited at short-latency by linear motion-and even the quantitative details are generally very similar. Thus, although the RFVR and OFR respond to very different patterns of global motion-radial vs. linear-they have very similar local spatiotemporal properties as though mediated by the same low-level, local-motion detectors, which we suggest are in the striate cortex. PMID:17706738

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

2007-09-01

149

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.

Boston, Wgbh

2002-01-01

150

Axial development and radial non-uniformity of flow in packed columns.  

PubMed

Flow inhomogeneity and axial development in low-pressure chromatographic columns have been studied by magnetic resonance imaging velocimetry. The columns studied included (a) an 11.7-mm I.D. column packed with either 50 microm diameter porous polyacrylamide, or 99 or 780 microm diameter impermeable polystyrene beads, and (b) a 5-mm I.D. column commercially packed with 10 microm polymeric beads. The packing methods included gravity settling, slurry packing, ultrasonication, and dry packing with vibration. The magnetic resonance method used averaged apparent fluid velocity over both column cross-sections and fluid displacements greater than one particle diameter and hence permits assessment of macroscopic flow non-uniformities. The results confirm that now non-uniformities induced by the conical distributor of the 11.7-mm I.D. column or the presence of voids at the column entrance relax on a length scale of the column radius. All of the 11.7-mm I.D. columns examined exhibit near wall channeling within a few particle diameters of the wall. The origins of this behavior are demonstrated by imaging of the radial dependence of the local porosity for a column packed with 780 microm beads. Columns packed with the 99-microm beads exhibit reduced flow in a region extending from ten to three-to-five particle diameters from the wall. This velocity reduction is consistent with a reduced porosity of 0.35 in this region as compared to approximately 0.43 in the bulk of the column. Ultrasonicated and dry-packed columns exhibit enhanced flow in a region located between approximately eight and 20 particle diameters from the wall. This enhancement maybe caused by packing density inhomogeneity and/or particle size segregation caused by vibration during the packing process. No significant non-uniformities on length scales of 20 microm or greater were observed in the commercially packed column packed with 10 microm particles. PMID:11860146

Park, Jaekeun C; Raghavan, Karthik; Gibbs, Stephen J

2002-02-01

151

Radial flow bioreactor for the creation of bioartificial liver and kidney.  

PubMed

A radial flow bioreactor (RFB) is used for a three-dimensional perfusion culture of hepatocellular carcinoma (HCC) cells and renal cells, to create a bioartificial liver and kidney. The cylindrical reactor is filled with porous cellulose microcarrier. RFB can be characterized as a system in which the medium flows from the periphery toward the center of the reactor, thereby delivering an adequate supply of oxygen and nutrients to cells at the center as well as at the periphery. HCC cells incubated in the RFB system at high density maintained viability for long periods of time. Proximal tubular cells (LLC-PK1) as well as HCC cells, but not human immortalized mesangial cells (HMC) were cultured in the RFB for more than 14 days. The mRNA expression of some enzymes involved in the urea cycle, cytochrome P450s in HCC cells, and the 1-alpha-hydroxylase (CYP27B1) in LLC-PK1 cells was higher than that in monolayer cultures. These results suggest that the RFB system composed of HCC cells or renal cells may be useful for a bioartificial liver and kidney. PMID:15808597

Iwahori, T; Matsuno, N; Johjima, Y; Konno, O; Akashi, I; Nakamura, Y; Hama, K; Iwamoto, H; Uchiyama, M; Ashizawa, T; Nagao, T

2005-01-01

152

Travel time approach to kinetically sorbing solute by diverging radial flows through heterogeneous porous formations  

NASA Astrophysics Data System (ADS)

Diverging radial flow takes place in a heterogeneous porous medium where the log conductivity Y = ln K is modeled as a stationary random space function (RSF). The flow is steady, and is generated by a fully penetrating well. A linearly sorbing solute is injected through the well envelope, and we aim at computing the average flux concentration (breakthrough curve). A relatively simple solution for this difficult problem is achieved by adopting, similar to Indelman and Dagan (1999), a few simplifying assumptions: (i) a thick aquifer of large horizontal extent, (ii) mildly heterogeneous medium, (iii) strongly anisotropic formation, and (iv) large Peclet number. By introducing an appropriate Lagrangian framework, three-dimensional transport is mapped onto a one-dimensional domain (?, t) where ? and t represent the fluid travel and current time, respectively. Central for this approach is the probability density function of the RSF ?that is derived consistently with the adopted assumptions stated above. Based on this, it is shown that the travel time can be regarded as a Gaussian random variable only in the far field. The breakthrough curves are analyzed to assess the impact of the hydraulic as well as reactive parameters. Finally, the travel time approach is tested against a forced-gradient transport experiment and shows good agreement.

Severino, Gerardo; de Bartolo, Samuele; Toraldo, Gerardo; Srinivasan, Gowri; Viswanathan, Hari

2012-12-01

153

The Potential Effects of a Biofeedback Writing Exercise on Radial Artery Blood Flow and Neck Mobility  

PubMed Central

Background: It has been suggested that sustained contraction of the deep neck muscles may reduce axial cervical range of motion (CROM) and radial artery blood flow velocity (vrad.art.mean). No studies have reported both phenomena in relation to acute hand, shoulder or neck trauma. Procedures: The CROM and vrad.art.mean were measured in 20 police officers prior to and immediately after a 2-hours drive on a motorcycle and immediately after a 1-minute writing exercise using biofeedback. The CROM was measured using separate inclinometers and the vrad.art.mean was measured in both arms just proximal to the wrist using echo-Doppler. Findings: During the study, one officer had a motorcycle accident resulting in acute symptoms of neck trauma. His vrad.art.mean was acutely reduced by 73% (right arm) and 45% (left arm). Writing with biofeedback increased his vrad.art.mean by 150% (right arm) and 80% (left arm). In the remaining 19 officers, the CROM to the right was significantly increased after the 2-hours driving task (p<0.05; paired subject t-test). Writing with biofeedback increased their CROM in both directions and vrad.art.mean in both arms (p<001). Conclusions: A 2-hours drive showed modest physical changes in the upper extremities. Biofeedback in writing tasks might relate to the influence of relaxation and diverting attention for neck mobility and arterial blood flow improvement.

Krullaards, Rob L.; Pel, Johan J. M.; Snijders, Chris J.; Kleinrensink, Gert-Jan

2009-01-01

154

Probing f-actin flow by tracking shape fluctuations of radial bundles in lamellipodia of motile cells.  

PubMed Central

We examined the dynamics of radial actin bundles based on time-lapse movies of polarized light images of living neuronal growth cones. Using a highly sensitive computer vision algorithm for tracking, we analyzed the small shape fluctuations of radial actin bundles that otherwise remained stationary in their positions in the growth cone lamellipodium. Using the tracking software, we selected target points on radial bundles and measured both the local bundle orientations and the lateral displacements between consecutive movie frames. We found that the local orientation and the lateral displacement of a target point are correlated. The correlation can be explained using a simple geometric relationship between the lateral travel of tilted actin bundles and the retrograde flow of f-actin structures. Once this relationship has been established, we have turned the table and used the radial bundles as probes to measure the velocity field of f-actin flow. We have generated a detailed map of the complex retrograde flow pattern throughout the lamellipodium. Such two-dimensional flow maps will give new insights into the mechanisms responsible for f-actin-mediated cell motility and growth.

Danuser, G; Oldenbourg, R

2000-01-01

155

1r2dinv: A finite-difference model for inverse analysis of two dimensional linear or radial groundwater flow  

USGS Publications Warehouse

We have developed a program for inverse analysis of two-dimensional linear or radial groundwater flow problems. The program, 1r2dinv, uses standard finite difference techniques to solve the groundwater flow equation for a horizontal or vertical plane with heterogeneous properties. In radial mode, the program simulates flow to a well in a vertical plane, transforming the radial flow equation into an equivalent problem in Cartesian coordinates. The physical parameters in the model are horizontal or x-direction hydraulic conductivity, anisotropy ratio (vertical to horizontal conductivity in a vertical model, y-direction to x-direction in a horizontal model), and specific storage. The program allows the user to specify arbitrary and independent zonations of these three parameters and also to specify which zonal parameter values are known and which are unknown. The Levenberg-Marquardt algorithm is used to estimate parameters from observed head values. Particularly powerful features of the program are the ability to perform simultaneous analysis of heads from different tests and the inclusion of the wellbore in the radial mode. These capabilities allow the program to be used for analysis of suites of well tests, such as multilevel slug tests or pumping tests in a tomographic format. The combination of information from tests stressing different vertical levels in an aquifer provides the means for accurately estimating vertical variations in conductivity, a factor profoundly influencing contaminant transport in the subsurface. ?? 2001 Elsevier Science Ltd. All rights reserved.

Bohling, G. C.; Butler, Jr. , J. J.

2001-01-01

156

Effects of water level fluctuation on radial oxygen loss, root porosity, and nitrogen removal in subsurface vertical flow wetland mesocosms  

Microsoft Academic Search

Laboratory experiments were conducted to investigate the effects of water level fluctuation on plant radial oxygen loss (ROL), root porosity, plant growth performance, and nitrogen dynamics in vertical subsurface flow wetland mesocosms. Four types of mesocosms were used: control with static water level, control with fluctuating water level, static water level with plants, and fluctuating water level with plants. Typha

S. Sasikala; Norio Tanaka; H. S. Y. Wah Wah; K. B. S. N. Jinadasa

2009-01-01

157

Convergence of the backward\\/forward sweep method for the load-flow analysis of radial distribution systems  

Microsoft Academic Search

This paper presents a study on the convergence characteristics of the backward\\/forward sweep method, which is one of the most effective methods for the load-flow analysis of the radial distribution systems. After revisiting the theoretical background, the convergence conditions and the evolution of the iterative process are investigated in detail for different load models. A dedicated study of the properties

E. Bompard; E. Carpaneto; G. Chicco; R. Napoli

2000-01-01

158

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...

159

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

160

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

161

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

162

Osteoblastic cell proliferation with uniform distribution in a large scaffold using radial-flow bioreactor.  

PubMed

Bioreactors employing different types of in vitro physiological cell stimulation have been developed to obtain three-dimensional cultivation for tissue engineering. The aim of this study was to determine whether osteoblastic cells proliferated uniformly over a large scaffold with a diameter of 18 mm and height of 10 mm under dynamic cultivation with the radial-flow bioreactor (RFB), and thereby ascertain the potential of this system in the regeneration of jaw bone. Mouse osteoblastic cells (MC3T3-E1) were seeded onto type 1 collagen sheets. Cells were then incubated outside the reactor for 6 h to produce precultured sheets. The six precultured sheets were then placed in the RFB to fabricate the scaffolds. Cells were dynamically cultured for 1 week at 37°C, pH 7.4, dissolved oxygen 6.86 ppm, and with the culture medium circulating at 3 mL/min. As a control, static cultivation cultured in the same manner without the circulating culture medium and single cultivation in a culture dish were performed. The resulting cell proliferation and cell distribution were analyzed. After 1 week of dynamic cultivation, cells showed a fivefold and fourfold increase with uniform distribution throughout the three-dimensional scaffolds than those under the static and single cultivation as a control, respectively. These results indicate that the RFB is a promising system for three-dimensional cultivation of osteoblastic cells for treating large bone defects by tissue engineering. PMID:20367244

Arano, Taichi; Sato, Toru; Matsuzaka, Kenichi; Ikada, Yoshito; Yoshinari, Masao

2010-12-01

163

Hepatic reconstruction from fetal porcine liver cells using a radial flow bioreactor  

PubMed Central

AIM: To examine the efficacy of the radial flow bioreactor (RFB) as an extracorporeal bioartificial liver (BAL) and the reconstruction of liver organoids using embryonic pig liver cells. METHODS: We reconstructed the liver organoids using embryonic porcine liver cells in the RFB. We also determined the gestational time window for the optimum growth of embryonic porcine liver cells. Five weeks of gestation was designated as embryonic day (E) 35 and 8 wk of gestation was designated as E56. These cells were cultured for one week before morphological and functional examinations. Moreover, the efficacy of pulsed administration of a high concentration hepatocyte growth factor (HGF) was examined. RESULTS: Both cell growth and function were excellent after harvesting on E35. The pulsed administration of a high concentration of HGF promoted the differentiation and maturation of these fetal hepatic cells. Microscopic examination of organoids in the RFB revealed palisading and showed that bile duct-like structures were well developed, indicating that the organoids were mini livers. Transmission electron microscopy revealed microvilli on the luminal surfaces of bile duct-like structures and junctional complexes, which form the basis of the cytoskeleton of epithelial tissues. Furthermore, strong expression of connexin (Cx) 32, which is the main protein of hepatocyte gap junctions, was observed. With respect to liver function, ammonia detoxification and urea synthesis were shown to be performed effectively. CONCLUSION: Our system can potentially be applied in the fields of BAL and transplantation medicine.

Ishii, Yuji; Saito, Ryota; Marushima, Hideki; Ito, Ryusuke; Sakamoto, Taro; Yanaga, Katsuhiko

2008-01-01

164

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

165

Gas chromatography with programming the mobile phase flow rate  

Microsoft Academic Search

The dependence of stationary phase bleeding on the carrier gas flow rate and column temperature is investigated. When the carrier gas flow rate is programmed the requirements on the thermostability of the stationary phase are less stringent than in case of temperature programming. Equations for the calculation of the main parameters for a linear program are derived. An exemple for

S. A. Volkov; Yu. A. Sultanovich; K. I. Sakodinskii

1979-01-01

166

The origins of radial fracture systems and associated large lava flows on Venus  

NASA Technical Reports Server (NTRS)

Magellan images have revealed the existence of systems of radial fractures on venus that are very similar in form to terrestrial dike swarms such as the Mackenzie swarm in Northern Canada. The association of many of the fracture systems with lava flows, calderas, and volcanic edifices further support the idea of a dike emplacement origin. A global survey of the Magellan images has allowed the location of 300 such fracture systems. Two types of fracture systems are defined. A series of models were developed to simulate the emplacement of dikes on Venus. Observations of fracture lengths and widths were then used to constrain the emplacement conditions. The model results show that the great length and relatively large width of the fractures can only be explained if the dikes that produce them were emplaced in high driving pressure (pressure buffered) conditions. Such conditions imply high rates of melt production, which is consistent with the melt being derived directly from a plume head. We have recently modeled the vertical emplacement of a dike from the top of a mantle plume and calculated the eruption rates such a dike would produce on reaching the surface. This modeling shows that eruption rates of approximately 0.1 cu km/hr can readily be generated by such a dike, consistent with the above results. However, the sensitivity of the model to dike width and therefore driving pressure means that eruption rates from dikes emplaced from the base of the crust or the head of a mantle plume could be orders of magnitude higher than this. Clearly, therefore, the model needs to be refined in order to better constrain eruption conditions. However, it is worth noting here that the initial results do show that even for moderate dike widths, eruption rates could be at least on the order of those estimated for terrestrial flood basalts.

Parfitt, Elisabeth A.; Wilson, Lionel; Head, James W., III

1992-01-01

167

Implementing transformer nodal admittance matrices into backward\\/forward sweep-based power flow analysis for unbalanced radial distribution systems  

Microsoft Academic Search

This paper proposes a new method to handle distribution transformers of various winding connections in the backward\\/forward sweep-based power flow analysis for unbalanced radial distribution systems. The method takes advantage of available nodal admittance matrices of distribution transformers, and can automatically solve the problem of conductively isolated subnetworks to obtain their equivalent phase-to-reference voltages. In addition, this paper presents a

Zhuding Wang; Fen Chen; Jingui Li

2004-01-01

168

Analytical solutions of nonaqueous-phase-liquid dissolution problems associated with radial flow in fluid-saturated porous media  

NASA Astrophysics Data System (ADS)

To derive analytical solutions for NAPL dissolution problems with radial flow.Three key factors can affect the propagating speed of an NAPL dissolution front.Three key factors can also affect the location and breakthrough time of an NAPL dissolution front.The Zhao number can be used to represent the overall hydrodynamic characteristic of a NAPL dissolution system.Several key factors can also affect the distribution pattern and evolution of the NAPL dissolution front.

Zhao, Chongbin; Hobbs, B. E.; Ord, A.

2013-06-01

169

Radial nonuniformity of flow structure in a liquid-solid circulating fluidized bed  

Microsoft Academic Search

Electrical conductivity probes were used to measure the radial distributions of solids holdup and liquid velocity in a liquid-solid circulating fluidized bed. These distributions are found to be non-uniform, unlike those in a non-circulating bed. The effects of superficial liquid velocity and particle circulation rate on the radial distributions of bed voidage and liquid velocity are studied. Based on the

W.-G. Liang; J.-X. Zhu; Y. Jin; Z.-Q. Yu; Z.-W. Wang; J. Zhou

1996-01-01

170

Continuous flow PCB radiolysis with real-time assessment by gas chromatography  

Microsoft Academic Search

We report the e-beam radiolysis of polychlorinated biphenyls (PCBs) in a continuous flow system, and the development of remote, real-time detection using gas chromatography. Aroclor-containing transformer oil was recirculated through an irradiation cell irradiated with 13-MeV electrons, at a flow rate of approximately 0.1L\\/min. The analytical equipment was protected from the beam by a 1.1-m concrete barrier. Data are presented

Aaron Ruhter; Rene’ G. Rodriguez; Bruce J. Mincher; Richard R. Brey

2006-01-01

171

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.

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

2009-01-01

172

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

173

THE INFLUENCE OF ORIFICE INSERTION IN RADIAL SWIRLING FLOW FOR LOW EMISSIONS COMBUSTION  

Microsoft Academic Search

This paper presents the effect of inserting swirler outlet orifice plate of different sizes at the exit plane of the flat blade radial air swirler in liquid fuel burner system. Tests were carried out with three different orifice plates with area ratios (orifice area to swirler exit area ratio) between 1.0 to 0.7 using 280 mm inside diameter combustor of

Mohamad Shaiful Ashrul Ishak; Mohammad Nazri; Blok A; Pusat Pengajian; Seberang Ramai

2008-01-01

174

Design and Fabrication of a High-Performance Brayton Cycle Radial-Flow Gas Generator.  

National Technical Information Service (NTIS)

The project concerned an investigation of Brayton-cycle space-power systems that use solar or nuclear energy as the heat source and an inert gas as the working fluid. Three pieces of radial turbomachinery were designed and fabricated, as follows: Compress...

1966-01-01

175

A modified Newton method for radial distribution system power flow analysis  

Microsoft Academic Search

A modified Newton method for radial distribution systems is derived in which the Jacobian matrix is in UDUT form, where U is a constant upper triangular matrix depending solely on system topology and D is a block diagonal matrix. With this formulation, the conventional steps of forming the Jacobian matrix, LU factorization and forward\\/back substitution are replaced by back\\/forward sweeps

Fan Zhang; C. S. Cheng

1997-01-01

176

An efficient iterative method for load-flow solution in radial distribution networks  

Microsoft Academic Search

In this paper, an efficient method for radial distribution networks solution is proposed. The efficiency of the presented strategy makes it suitable for distribution automation applications. The method is based on an iterative algorithm with some special procedures to increase the convergence speed; the bus voltages are considered as state variables according to approaches that are common in literature. After

A. Augugliaro; L. Dusonchet; M. G. Ippolito; E. Riva Sanseverind

2001-01-01

177

A modified Newton method for radial distribution system power flow analysis  

SciTech Connect

A modified Newton method for radial distribution systems is derived in which the Jacobian matrix is in UDU{sup T} form, where U is a constant upper triangular matrix depending solely on system topology and D is a block diagonal matrix. With this formulation, the conventional steps of forming the Jacobian matrix, LU factorization and forward/back substitution are replaced by back/forward sweeps on radial feeders with equivalent impedances. Tests on several large distribution systems ranged from 490 to 1651 in nodes, 0.15 to 5.48 in r/x ratio and 0.0004 {Omega} to 3.07 {Omega} in line impedance have shown that the proposed method is as robust and efficient as the back/forward sweep method. The proposed method can be applied to other applications, such as state estimation. The proposed method can also be extended to the solution of systems with loops, dispersed generators and three phase (unbalanced) representation.

Zhang, F. [ABB Automated Distribution Div., Cary, NC (United States)] [ABB Automated Distribution Div., Cary, NC (United States); Cheng, C.S. [Pacific Gas and Electric Co., San Francisco, CA (United States). Electric Supply Systems] [Pacific Gas and Electric Co., San Francisco, CA (United States). Electric Supply Systems

1997-02-01

178

Thermal stresses due to a uniform heat flow past a circular hole with a radial edge crack  

SciTech Connect

The problem solved here is that of finding the stresses in an isotropic, linear, thermoelastic solid when a uniform heat flow is disturbed by the presence of an insulated circular hole with a radial edge crack. By superimposing a Mellin-transform solution of the equations of thermoelasticity on a Michell series solution the author reduces the problem to a pair of singular integral equations which are then solved numerically. The stress-intensity factors and crack-formation energies, quantities of interest to workers in fracture mechanics, are then calculated.

Edmonds, G.F.

1987-01-01

179

Behavior of polysaccharide assemblies in field-flow fractionation and size-exclusion chromatography  

Microsoft Academic Search

Asymmetric flow field-flow fractionation (AsFlFFF) and high-performance size-exclusion chromatography (HPSEC) are techniques\\u000a for separating and characterizing macromolecules; until now the latter is more utilized for analyzing polysaccharides. The\\u000a demand for characterizing complex, high-molar-mass polysaccharides has raised interest in the use of AsFlFFF in analyzing\\u000a polymeric carbohydrates in addition to HPSEC. In this paper, we compare the behavior of arabinoxylan aggregates

Leena Pitkänen; Maija Tenkanen; Päivi Tuomainen

2011-01-01

180

Integrated horizontal-flow anaerobic and radial-flow aerobic reactors for the removal of organic matter and nitrogen from domestic sewage.  

PubMed

This paper presents the conception and discusses the results obtained from the operation of an integrated biological anaerobic/aerobic/anaerobic system composed of horizontal-flow anaerobic and radial-flow aerobic reactors for domestic sewage treatment. The performance of a horizontal-flow anaerobic immobilized biomass reactor, with five stages,followed by a radial-flow aerobic immobilized biomass reactor was evaluated along 22 weeks. After the 14th week, the last stage of the HAIB reactor was used as a denitrifying unit. Polyurethane foam cubic matrices with 1-cm sides were used as support for biomass immobilization in all the units. The influent domestic sewage presented mean chemical oxygen demand of 365 +/- 71 mg. 1(-1) and the temperature was 23 +/- 3degrees C. The integrated system achieved COD removal efficiency of 90% while the maximum ammonium removal efficiency was 97% in the aerobic post-treatment unit. The nitrification process was found to be better represented by first-order reactions in series model. The apparent first-order kinetic coefficient for nitrate formation was about 50 times higher than that estimated for the nitrite formation. The denitrification process was well represented by a Monod-type kinetic model. The maximum specific denitrifying rate and the half-saturation coefficient were 2.9 x 10(-4) mg NO(3)(-)-N mg(-1) VSS h(-1) and 19.4 mg NO(3)(-)-N 1(-1), respectively. PMID:12641252

Vieira, L G T; Fazolo, A; Zaiat, M; Foresti, E

2003-01-01

181

Computations of the three-dimensional flow and heat transfer within a coolant passage of a radial turbine blade  

NASA Technical Reports Server (NTRS)

A numerical code is developed for computing three-dimensional, turbulent, compressible flow within coolant passages of turbine blades. The code is based on a formulation of the compressible Navier-Stokes equations in a rotating frame of reference in which the velocity dependent variable is specified with respect to the rotating frame instead of the inertial frame. The algorithm employed to obtain solutions to the governing equation is a finite-volume LU algorithm that allows convection, source, as well as diffusion terms to be treated implicitly. In this study, all convection terms are upwind differenced by using flux-vector splitting, and all diffusion terms are centrally differenced. This paper describes the formulation and algorithm employed in the code. Some computed solutions for the flow within a coolant passage of a radial turbine are also presented.

Shih, T. I.-P.; Roelke, R. J.; Steinthorsson, E.

1991-01-01

182

Cylindrically confined pair-ion-electron and pair-ion plasmas having axial sheared flow and radial gradients  

SciTech Connect

The linear and nonlinear dynamics of pair-ion (PI) and pair-ion-electron plasmas (PIE) have been investigated in a cylindrical geometry with a sheared plasma flow along the axial direction having radial dependence. The coupled linear dispersion relation of low frequency electrostatic waves has been presented taking into account the Guassian profile of density and linear gradient of sheared flow. It is pointed out that the quasi-neutral cold inhomogeneous pure pair ion plasma supports only the obliquely propagating convective cell mode. The linear dispersion relation of this mode has been solved using boundary conditions. The nonlinear structures in the form of vortices formed by different waves have been discussed in PI and PIE plasmas.

Batool, Nazia; Saleem, H. [National Centre for Physics (NCP), Quaid-i-Azam University Campus, Islamabad (Pakistan)] [National Centre for Physics (NCP), Quaid-i-Azam University Campus, Islamabad (Pakistan)

2013-10-15

183

Forward-rapidity azimuthal and radial flow of identified particles for s=200 GeV Au+Au collisions  

NASA Astrophysics Data System (ADS)

A strong azimuthal flow signature at RHIC suggests rapid system equilibration leading to an almost perfect fluid state. The longitudinal extent of the flow behavior depends on how this state is formed and can be studied by measuring the pseudorapidity and transverse momentum dependence of the second Fourier component (?(p)) of the azimuthal angular distribution. We report on a measurement of identified-particle ? as a function of p(0.5-2.0 GeV/c), centrality (0-25%, 25-50%), and pseudorapidity (0??<3.2) for s=200 GeV Au+Au collisions. The BRAHMS spectrometers are used for particle identification (?, K, p) and momentum determination and the BRAHMS global detectors are used to determine the corresponding reaction-plane angles. The results are discussed in terms of the pseudorapidity dependence of constituent quark scaling and in terms of models that develop the complete (azimuthal and radial) hydrodynamic aspects of the forward dynamics at RHIC.

Brahms Collaboration; Sanders, S. J.; BRAHMS Collaboration

2009-11-01

184

Effects of Magnetic Field on Entropy Generation in Flow and Heat Transfer due to a Radially Stretching Surface  

NASA Astrophysics Data System (ADS)

We investigate the effects of magnetic field on the entropy generation during fluid flow and heat transfer due to the radially stretching surface. The partial differential equations governing the flow and heat transfer phenomenon are transformed into nonlinear ordinary differential equations by using suitable similarity transformations. These equations are then solved by the homotopy analysis method and the shooting technique. The effects of the magnetic field parameter M and the Prandtl number Pr on velocity and the temperature profiles are presented. Moreover, influence of the magnetic field parameter M and the group parameter Br/? on the local entropy generation number Ns as well as the Bejan number Be are inspected. It is observed that the magnetic field is a strong source of entropy production in the considered problem.

Adnan Saeed, Butt; Asif, Ali

2013-02-01

185

Efficient three-phase power-flow method for unbalanced radial distribution systems  

Microsoft Academic Search

This paper presents an efficient three-phase power flow algorithm for distribution network analysis. A new transformer model with various connections is implemented in the forward\\/backward sweep power flow method. The developed method provides an effective solution to the singularity problem of the nodal admittance submatrices appeared in some transformer configurations. Different load models and capacitor banks are also implemented with

Karar Mahmoud; Mamdouh Abdel-Akher

2010-01-01

186

Radial Hele-Shaw flow with suction: Fully nonlinear pattern formation  

NASA Astrophysics Data System (ADS)

We study the development of intricate, fully nonlinear immiscible interfacial patterns in the suction-driven radial Hele-Shaw problem. The complex-shaped, contracting fluid-fluid interface arises when an initially circular blob of more viscous fluid, surrounded by less viscous one, is drawn into an eccentric point sink. We present sophisticated numerical simulations, based on a diffuse interface model, that capture the most prominent interfacial features revealed by existing experimental studies of the problem. The response of the system to changes in the capillary number is investigated, accurately revealing the occurrence of finger competition phenomena, and correctly describing the velocity behavior of both inward- and outward-pointing fingers. For the large-capillary-number regime, a set of complex interfacial features (finger merging, shielding, and pinch-off) whose experimental realization is still not available, are predicted.

Chen, Ching-Yao; Huang, Yu-Sheng; Miranda, José A.

2014-05-01

187

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)] [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)] [Electricite de France, R and D, SINETICS, 1 Av. du General de Gaulle, 92141, Clamart (France)

2013-07-01

188

North-south asymmetry in polar coronal holes during sunspot minima and non-radial flows in the solar wind.  

NASA Astrophysics Data System (ADS)

The solar wind parameters and solar coronal structures have been analyzed during sunspot minimum periods of sunspot cycles 23 and 24. Polar coronal hole area is observed to be large in the northern hemisphere of the sun compared to that during southern hemisphere during the minimum periods of sunspot cycle 23. A helio-latitudinal dependence of density of the solar wind is observed in the northern hemisphere of the sun during this period. This phenomenon reverses during sunspot minimum periods of cycle 24. A close association of non-radial flows of solar wind with density variations is observed during the period of study. This can be explained in terms of the change in solar wind mass flux transport in the solar corona.

Pereira, Felix; Philip, Bijoy

2012-07-01

189

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

190

A three-dimensional Navier-Stokes stage analysis of the flow through a compact radial turbine  

NASA Technical Reports Server (NTRS)

A steady, three-dimensional Navier-Stokes average passage computer code is used to analyze the flow through a compact radial turbine stage. The code is based upon the average passage set of equations for turbomachinery, whereby the flow fields for all passages in a given blade row are assumed to be identical while retaining their three-dimensionality. A stage solution is achieved by alternating between stator and rotor calculations, while coupling the two solutions by means of a set of axisymmetric body forces which model the absent blade row. Results from the stage calculation are compared with experimental data and with results from an isolated rotor solution having axisymmetric inlet flow quantities upstream of the vacated stator space. Although the mass-averaged loss through the rotor is comparable for both solutions, the details of the loss distribution differ due to stator effects. The stage calculation predicts smaller spanwise variations in efficiency, in closer agreement with the data. The results of the study indicate that stage analyses hold promise for improved prediction of loss mechanisms in multi-blade row turbomachinery, which could lead to improved designs through the reduction of these losses.

Heidmann, James D.

1991-01-01

191

One-dimensional analysis of plane and radial thin film flows including solid-body rotation  

Microsoft Academic Search

The flow of a thin liquid film with a free surface along a horizontal plate which emanates from a pressurized vessel is examined by integrating the equations of motion across the thin liquid layer and discretizing the integrated equations using finite difference techniques. The effects of 0-g and solid-body rotation will be discussed. The two cases of interest are plane

S. Thomas; W. Hankey; A. Faghri; T. Swanson

1989-01-01

192

Unbalance power flow calculation for a radial distribution system using forward-backward propagation algorithm  

Microsoft Academic Search

Three-phase power flow for unbalance distribution system is carried out using forward- backward propagation technique. The equivalent injection current method is employed to represent the loads and shunt admittances. The algorithm starts with mapping the distribution network to determine the forward and backward propagation paths. The backward propagation is used to calculate branch currents using the bus injection currents. The

A. Ulinuha; M. A. S. Masoum; S. M. Islam

2007-01-01

193

A new topology structure and load flow solution for radial distribution networks  

Microsoft Academic Search

In this paper an efficient power flow solution with topology analysis is studied to support distribution network reconfiguration techniques in practice use. A new topology model is proposed which defined as a tree node data structure to describe the connecting relationship among the nodes dynamically. The depth-first search strategy with node storage queue technique is also used to form the

Liu Li; Guo Zhizhong; Wang Chengmin

2002-01-01

194

On the existence and uniqueness of load flow solution for radial distribution power networks  

Microsoft Academic Search

On the basis of voltage level, an electric power system can be viewed as consisting of a generation system, a transmission system, and a distribution system. The steady-state operation of a power system requires that the power supply, transmission losses, and load demand be balanced, as described by the load flow equations. The configuration of a transmission network is that

H.-D. Chiang; M. E. Baran

1990-01-01

195

Flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry with a supersonic molecular beam.  

PubMed

A new approach of flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry (GC x GC-MS) with supersonic molecular beam (SMB) and a quadrupole mass analyzer is presented. Flow modulation uniquely enables GC x GC-MS to be achieved even with the limited scan speed of quadrupole MS, and its 20 ml/min column flow rate is handled, splitless, by the SMB interface. Flow modulation GC x GC-SMB-MS shares all the major benefits of GC x GC and combines them with GC-MS including: (a) increased GC separation capability; (b) improved sensitivity via narrower GC peaks; (c) improved sensitivity through reduced matrix interference and chemical noise; (d) polarity and functional group sample information via the order of elution from the second polar column. In addition, GC x GC-SMB-MS is uniquely characterized by the features of GC-MS with SMB of enhanced and trustworthy molecular ion plus isotope abundance analysis (IAA) for improved sample identification and fast fly-through ion source response time. The combination of flow modulation GC x GC with GC-MS with SMB (supersonic GC-MS) was explored with complex matrices such as diesel fuel analysis and pesticide analysis in agricultural products. PMID:16834991

Kochman, Maya; Gordin, Alexander; Alon, Tal; Amirav, Aviv

2006-09-29

196

Prediction of heat transfer to a thin liquid film in plane and radially spreading flows  

SciTech Connect

The numerical solution of a thin film flow is difficult since the free surface geometry changes along the path of the flow, is unknown ahead of time, and cannot be fitted in a regular Cartesian or cylindrical coordinate system. Therefore, most theoretical studies in this area were related to the development of approximate analytical models (Faghri and Seban, 1981; Chaudhury, 1964). The finite-difference solution was attempted only for a falling film (Faghri and Payvar, 1979) where the film thickness could be approximated to be uniform. Recently, Rahman et al. (1990a) have developed a finite-difference solution method applicable for the fluid mechanics of thin film flows under zero and normal gravity. A body-fitted coordinate system was used where the free surface was approximated by a curve and iterated for the best possible solution. The present study is intended to incorporate the energy equation in the solution algorithm of Rahman et al. (1990a) to compute the heat transfer to a thin film in the presence or absence of gravity. In addition to the enhancement of the knowledge of thin film heat transfer, the results of the present study may be directly applicable to the design of space-based cooling systems.

Rahman, M.M.; Faghri, A.; Hankey, W.L. (Wright State Univ., Dayton, OH (USA)); Swanson, T.D. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

1990-08-01

197

Computerized optimization of flows and temperature gradient in flow modulated comprehensive two-dimensional gas chromatography.  

PubMed

Informational entropy and syentropy percent were used to optimize the flows in the first (1D) and in the second (2D) dimension ((1)Fm and (2)Fm, respectively) as well as the temperature program rate (r) for the flow modulated GC×GC-FID separation of C6-C12 aromatic hydrocarbons in a low boiling petrochemical sample. The separations were performed on a column series consisting of a 25m×0.25mm i.d.×0.2?m df of the polar ionic liquid SLB-IL 100 (1,9-di(3-vinylimidazolium)nonane bis(trifluoromethylsulfonyl)imide) in the first dimension and 5m×0.25mm i.d.×0.25?m df apolar HP-5MS (5% phenyl-95% methylpolysiloxane) in the second dimension. A dependence of a distribution of individual aromatic hydrocarbons in the 2D retention plane on the carrier gas flows ((1)Fm, and (2)Fm,) and temperature gradient (r) was examined in this study. It was found that informational entropy and synentropy percent are advantageous criteria to characterize the distribution of peaks in the 2D retention plane. Maximum informational entropy and synentropy percents correspond to the maximum distribution of C6-C12 aromatic hydrocarbons in the corresponding 2D retention plane gained by the given separation using optimized values of individual carrier gas column volume flows and the temperature rate at the temperature programmed GC×GC separations. PMID:24861782

Májek, Pavel; Krup?ík, Ján; Gorovenko, Roman; Spánik, Ivan; Sandra, Pat; Armstrong, Daniel W

2014-07-01

198

Three-Dimensional Dynamics of Solar Coronal Mass Ejections: Radial and Transverse Expansion in an Asymmetric Ambient Flow Field  

NASA Astrophysics Data System (ADS)

The magnetic field structure underlying coronal mass ejections (CMEs) is that of a 3D magnetic flux rope with its fixed footpoints anchored in the photosphere. The momentum of an expanding flux rope is coupled to the ambient plasma via drag. The corona and solar wind plasma is characterized by a radially outward flow field so that the dominant flow is parallel to the motion of the apex of an expanding CME flux rope but is orthogonal to the expansion in the transverse direction. The gravitational force is also parallel to the apex motion and orthogonal to the transverse expansion motion. Thus, the apex and the flanks experience significantly different drag and gravity forces and therefore different net force. We have extended the existing erupting flux rope (EFR) model of CMEs, which assumes the toroidal axis of the expansion flux rope to be a segment of circular arc with two fixed footpoints, to self-consistently calculate the forces acting on the apex and the flanks. This extension allows one to calculate the coupled expansion for the apex and flanks. We characterize the resulting structure with a semi-major axis and semi-minor radii, i.e., as an ellipse. It is shown that the 3D dynamics are critically determined by the inductance of the new geometry.

Kunkel, Valbona; Chen, James

2012-10-01

199

Possible evidence for radial flow of heavy mesons in d + Au collisions  

NASA Astrophysics Data System (ADS)

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 possibly high multiplicity p + p collisions at the LHC). The measurements in p + Pb and d + Au collisions are both qualitatively and quantitatively similar to what is seen in 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 v2. Measurements of the transverse momentum spectra of electrons from the decay of D and B mesons in d + Au collisions show an enhancement in central collisions relative to p + p collisions. We employ the blast-wave model to determine if the flow of heavy quarks in d + Au and p + Pb collisions 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.

Sickles, Anne M.

2014-04-01

200

Redundant Vasodilator Pathways Underlying Radial Artery Flow-Mediated Dilation Are Preserved in Healthy Aging  

PubMed Central

Background. Blocking nitric oxide (NO) and vasodilator prostanoids (PN) does not consistently reduce flow-mediated dilation (FMD) in young adults. The impact of aging on the contribution of NO and PG to FMD is unknown. Methods. FMD was measured in older adults (n = 10, 65 ± 3?y) after arterial infusion of saline, N(G)-monomethyl-L-arginine (L-NMMA), and ketorolac + L-NMMA. Data were compared to published data in young adults. Results. L-NMMA reduced FMD in older adults (8.9 ± 3.6 to 5.9 ± 3.7%) although this was not statistically significant (P = 0.08) and did not differ (P = 0.74) from the reduction observed in young adults (10.0 ± 3.8 to 7.6 ± 4.7%; P = 0.03). Blocking PN did not affect FMD in young or older adults. In older adults, L-NMMA reduced (n = 6; range = 36–123% decrease), augmented (n = 3; 10–122% increase), or did not change FMD (n = 1; 0.4% increase). After PN blockade, FMD responses were reduced (n = 2), augmented (n = 6), or unaffected (n = 1). Conclusions. NO or PN blockade did not consistently reduce FMD in healthy older adults, suggesting the existence of redundant vasodilator phenotypes as observed previously in young adults.

Ballard, Kevin D.; Tschakovsky, Michael E.; Zaleski, Amanda L.; Polk, Donna M.; Thompson, Paul D.; Kiernan, Francis J.; Parker, Beth A.

2014-01-01

201

Sample stacking and sweeping in microemulsion electrokinetic chromatography under pH-suppressed electroosmotic flow.  

PubMed

Two on-line sample concentration techniques, sample stacking and sweeping under pH-suppressed electroosmotic flow, were evaluated in microemulsion electrokinetic chromatography. The concept of stacking with anion selective electrokinetic injection and a water plug in a reverse-migrating microemulsion (SASIW-RMME) was brought forward in this article. Six flavonoids were concentrated using a microemulsion consisting of 80 mM sodium dodecyl sulfate, 1.2% (v/v) ethyl acetate, 0.6% (v/v) 1-butanol, 10% acetonitrile (v/v) and 50 mM phosphoric acid (pH* 1.8). Significant detector response improvements were achieved. The limits of detection were in the low ng/ml level. Finally, the sample of Fructus aurantii Immaturus was analyzed using sweeping technique. PMID:18433762

Zhu, Jinhua; Qi, Shengda; Zhang, Huige; Chen, Xingguo; Hu, Zhide

2008-05-30

202

Adsorption studies of gases on Pt-Rh bimetallic catalysts by reversed-flow gas chromatography  

SciTech Connect

In the present work, the relatively new technique of reversed-flow gas chromatography was applied for the study of adsorption of carbon monoxide, oxygen, and carbon dioxide on Pt-Rh bimetallic catalysts. Using suitable mathematical analysis, equations were derived by means of which rate constants for adsorption, desorption, and disproportionation reaction were calculated. From the variation of these rate constants with temperature and the nature of the catalyst (Pt content), as well as from the finding that the CO adsorption is a dissociative process, useful conclusions concerning the mechanism for the CO oxidation reaction over Pt-Rh bimetallic catalysts were extracted. The catalytic fractional conversions for the CO disproportionation reaction were found to be higher for the Pt-RH bimetallic catalysts than those for the pure Pt catalyst, indicating the presence of beneficial Pt-Rh synergism.

Gavril, D.; Koliadima, A.; Karaiskakis, G. [Univ. of Patras (Greece). Dept. of Chemistry] [Univ. of Patras (Greece). Dept. of Chemistry

1999-05-25

203

Microfluidic valve geometries and possibilities for flow switching in gas chromatography  

NASA Astrophysics Data System (ADS)

Classical multi-(two-)dimensional separations in gas chromatography (GC) require switching systems to transfer the gas flow stream from the first to second dimension. This can be accomplished by valve systems, but is more suitably effected by pressure balanced systems, such as the Deans' switch method. Recent developments in microfluidics and related micro-technologies should make gas phase switching much more effective. The capillary flow technology platform of Agilent Technologies is an example of recent developments introduced to GC. Thus various Deans' switch pressure balanced devices, stream splitters, and column couplings bring new capabilities to analytical GC. We are uniquely placed to take advantage of the new devices, owing to our development of advanced operational methods in GC which can make use of microfluidic capillary couplings, and novel cryogenic approaches that deliver performance previously impossible with conventional methods. Multidimensional chromatographic flow switching to isolate pure compounds from complex mixtures suggests many potential applications for enhanced chemical analysis. Multiple dimensions of GC analysis, capabilities for integrating different spectroscopic detection methods for chemical identification of isolated chemical species including mass spectrometry, nuclear magnetic resonance and Fourier transform infrared, can be proposed. Applications in the essential oils and petrochemical area will be outlined.

Marriott, Philip J.; Eyres, Graham T.; Urban, Sylvia; Rühle, Christian

2008-12-01

204

Continuous synthesis and purification by direct coupling of a flow reactor with simulated moving-bed chromatography.  

PubMed

Continuous synthesis meets continuous purification to produce pure products from crude reaction mixtures. In the nucleophilic aromatic substitution of 2,4-difluoronitrobenzene with morpholine the desired monosubstituted product can be continuously separated from the byproducts in a purity of over 99 % by coupling a flow reactor to a simulated moving bed (SMB) chromatography module. PMID:22674846

O'Brien, Alexander G; Horváth, Zoltán; Lévesque, François; Lee, Ju Weon; Seidel-Morgenstern, Andreas; Seeberger, Peter H

2012-07-01

205

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

206

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

207

Column properties and flow profiles of a flat, wide column for high-pressure liquid chromatography  

SciTech Connect

The design and the construction of a pressurized, flat, wide column for high-performance liquid chromatography (HPLC) are described. This apparatus, which is derived from instruments that implement over-pressured thin layer chromatography, can carry out only uni-dimensional chromatographic separations. However, it is intended to be the first step in the development of more powerful instruments that will be able to carry out two-dimensional chromatographic separations, in which case, the first separation would be a space-based separation, LC{sup x}, taking place along one side of the bed and the second separation would be a time-based separation, LC{sup t}, as in classical HPLC but proceeding along the flat column, not along a tube. The apparatus described consists of a pressurization chamber made of a Plexiglas block and a column chamber made of stainless steel. These two chambers are separated by a thin Mylar membrane. The column chamber is a cavity which is filled with a thick layer (ca. 1 mm) of the stationary phase. Suitable solvent inlet and outlet ports are located on two opposite sides of the sorbent layer. The design allows the preparation of a homogenous sorbent layer suitable to be used as a chromatographic column, the achievement of effective seals of the stationary phase layer against the chamber edges, and the homogenous flow of the mobile phase along the chamber. The entire width of the sorbent layer area can be used to develop separations or elute samples. The reproducible performance of the apparatus is demonstrated by the chromatographic separations of different dyes. This instrument is essentially designed for testing detector arrays to be used in a two-dimensional LC{sup x} x LC{sup t} instrument. The further development of two-dimension separation chromatographs based on the apparatus described is sketched.

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

2008-01-01

208

Vertical and lateral propagation of radial dikes inferred from the flow-direction analysis of the radial dike swarm in Komochi Volcano, Central Japan  

NASA Astrophysics Data System (ADS)

Dikes with lateral and outward intrusion directions (named L-type dike) and dikes with vertical and upward intrusion directions (V-type dike) are recognized in a radial dike swarm of Komochi Volcano, Japan, by the combined analysis of the preferred orientations of deformed vesicles and anisotropy of magnetic susceptibility (AMS). Intrusion directions of magmas were examined for 41 dike outcrops. Among them, 19 dikes were classified as L-type dike and 15 dikes were as V-type. The L-type dikes distribute over the area of the dike swarm radiating from the central conduit, which is named Daikokuiwa stock, and the V-type dikes occur mainly in the peripheral portion of the volcano. The L-type dikes are characterized with evolved whole-rock compositions similar to those of rocks consisting of the central conduit, whereas the V-type dikes have less-fractionated composition and are enrich in mafic phenocryst as compared to the L-type dikes. The outward intrusion directions of the L-type dikes and their petrological similarity to the rock of the central conduit indicate that these dikes intruded from the shallow part of the central conduit where the magmas underwent fractional crystallization and degassing. The petrological characteristics of the V-type dikes suggest that the less-fractionated magma intruded directly from a magma chamber, in which mafic phenocryst crystals accumulated. The larger dike thickness and higher magnetic foliation of the V-type dike as compared to the L-type dike indicate higher magmatic overpressure, which was possibly result of the direct connection to the pressurized magma chamber and vertical-growth of the dikes with buoyant magma. Solidification of the central conduit is favorable for the accumulation of internal excess pressure in the magma chamber to break the wall rock. Fissure eruptions independent of the central conduit have occurred in many volcanoes and these fissure eruptions might be fed by the dikes directly propagated from the deeper magma chamber.

Geshi, Nobuo

2008-06-01

209

Transient solid-fluid temperature responses in a spherical packed-bed thermal storage unit to a single-blow application of radial mass flow  

SciTech Connect

A spherical storage unit is inherently compact and free from heat losses across side walls. And, if the flow is radially inward, it has the additional advantage of presenting the bulk of its volume (with larger radius near the inlet) to the large temperature difference between the fluid stream and the solid bed prevailing near the entrance of all packed-bed units, especially during the transient stage. The present paper simulates numerically the transient temperature responses of both the fluid stream and the solid bed (two-phase) arranged in the form of a spherical shell, with a single-blow application of radial flow, considering the conductive effect in the solid, and with realistic boundary conditions.

Lu, P.C.; Kow, L.C.

1983-12-01

210

Consideration of the tube radial distribution of the carrier solvents in a capillary tube under laminar flow conditions and computer simulation.  

PubMed

When the ternary mixed solvents of a water-hydrophilic/hydrophobic organic solvent mixture are delivered under microspace under laminar flow conditions, the solvent molecules are radially distributed in the microspace, and generate a major inner phase and a minor outer phase. We call this fluidic phenomenon as the tube radial distribution phenomenon (TRDP). In this paper, phase formation in the TRDP was collectively considered based on experimental data, such as the inner and outer phase formation in a microchannel under laminar flow conditions, the phase diagram for the ternary mixed solvents, the solvent-component ratios required for the TRDP, and the phase transformation in a batch vessel above atmospheric pressure, which were mainly reported in our previous papers. Furthermore, the formation of inner and outer phases in a capillary tube was simulated with the two-component solvents mixture model of water and ethyl acetate. Phase formations in capillary tubes were expressed through computer simulations. PMID:22687935

Jinno, Naoya; Masuhara, Yuji; Kobayashi, Tomoya; Tainaka, Naoya; Tanigawa, Yusuke; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2012-01-01

211

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

SciTech Connect

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, multiribbed 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. (Whittle Lab., Cambridge (United Kingdom))

1994-01-01

212

Comprehensive multidimensional separations of peptides using nano-liquid chromatography coupled with micro free flow electrophoresis.  

PubMed

The throughput of existing liquid phase two-dimensional separations is generally limited by the peak capacity lost due to under sampling by the second dimension separation as peaks elute off the first dimension separation. In the current manuscript, a first dimension nanoliquid chromatography (nLC) separation is coupled directly with a second dimension micro free flow electrophoresis (?FFE) separation. Since ?FFE performs continuous separations, no complicated injection or modulation is necessary to couple the two techniques. Analyte peaks are further separated in ?FFE as they elute off the nLC column. A side-on interface was designed to minimize dead volume in the nLC × ?FFE interface, eliminating this as a source of band broadening. A Chromeo P503 labeled tryptic digest of BSA was used as a complex mixture to assess peak capacity. 2D nLC × ?FFE peak capacities as high as 2,352 could be obtained in a 10 min separation window when determined according to the product of the first and second dimension peak capacities. After considering the orthogonality of the two separation modes and the fraction of separation space occupied by peaks, the usable peak capacity generated was determined to be 776. The 105 peaks/min generated using 2D nLC × ?FFE was nearly double the previously reported maximum peak capacity production rate achieved using online LC × LC. PMID:24742025

Geiger, Matthew; Frost, Nicholas W; Bowser, Michael T

2014-05-20

213

Fully automated screening of veterinary drugs in milk by turbulent flow chromatography and tandem mass spectrometry  

PubMed Central

There is an increasing interest in screening methods for quick and sensitive analysis of various classes of veterinary drugs with limited sample pre-treatment. Turbulent flow chromatography in combination with tandem mass spectrometry has been applied for the first time as an efficient screening method in routine analysis of milk samples. Eight veterinary drugs, belonging to seven different classes were selected for this study. After developing and optimising the method, parameters such as linearity, repeatability, matrix effects and carry-over were studied. The screening method was then tested in the routine analysis of 12 raw milk samples. Even without internal standards, the linearity of the method was found to be good in the concentration range of 50 to 500 µg/L. Regarding repeatability, RSDs below 12% were obtained for all analytes, with only a few exceptions. The limits of detection were between 0.1 and 5.2 µg/L, far below the maximum residue levels for milk set by the EU regulations. While matrix effects—ion suppression or enhancement—are obtained for all the analytes the method has proved to be useful for screening purposes because of its sensitivity, linearity and repeatability. Furthermore, when performing the routine analysis of the raw milk samples, no false positive or negative results were obtained.

Stolker, Alida A. M.; Peters, Ruud J. B.; Zuiderent, Richard; DiBussolo, Joseph M.

2010-01-01

214

Purification of hemoglobin by ion exchange chromatography in flow-through mode with PEG as an escort.  

PubMed

Development of hemoglobin-based blood substitutes requires production of highly purified hemoglobin. Process of hemoglobin purification by ion exchange chromatography in flow-through mode was researched and optimized. Three kinds of media including, QMA Spherosil LS (Biosepra, France) and Q Sepharose Big Beads (Amersham Bioscience, Sweden), and an anion exchange membrane column, Mustang Q (PALL, USA) were investigated and compared. Adding polyethylene glycol (PEG) as an escort in ion exchange chromatography improved the purity and recovery, and the recovery in the chromatography was increased from 75 to 95%. The mechanism of PEG effects on chromatography was discussed. The optimal chromatography step, in combination with hypotonic dilution hemolyzing and membrane separation, formed an integrated hemoglobin purification process. The total recovery in the process was 87.6%. The activity of hemoglobin was well preserved: P50 23.2 mmHg, and Hill coefficient 2.31. The product appeared as a single band in SDS-PAGE, and GF-HPLC showed only one peak. The purity of the prepared hemoglobin was more than 99.9%. The optimized process is time saving and suitable for large-scale preparation of hemoglobin to provide materials for further preparation of blood substitutes. PMID:15274429

Lu, Xiuling; Zhao, Dongxu; Su, Zhiguo

2004-05-01

215

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

216

Binary Particle Swarm Optimization for Optimization of Photovoltaic Generators in Radial Distribution Systems Using Probabilistic Load Flow  

Microsoft Academic Search

This article shows that technical constraints must be considered in radial distribution networks, where voltage regulation is one of the primary problems in distributed generation photovoltaic systems. Loads and distributed generation production are modeled as random variables. Results prove that the proposed method can be applied for keeping voltages within desired limits at all load buses of a photovoltaic grid-connected

F. J. Ruiz-Rodriguez; M. Gomez-Gonzalez; F. Jurado

2011-01-01

217

Analysis of perfluoroalkyl substances in cord blood by turbulent flow chromatography coupled to tandem mass spectrometry.  

PubMed

A fast on-line analytical method based on turbulent flow chromatography (TFC) in combination with tandem mass spectrometry has been applied for the first time for the analysis of eighteen perfluoroalkyl substances (PFASs), in cord blood. A simple and rapid sample pre-treatment was optimised consisting on protein precipitation of 100 ?L of sample with acetonitrile (1:1) followed by centrifugation during 10 min. The method was adapted to be sensitive enough and robust with minimum sample injection volume requirements (20 ?L). The optimised methodology presented method limits of detection (MLOD) between 0.031 and 0.76 ?g/L, detection capabilities (CC?) in the range between 0.005 and 0.99 ?g/L and decision limits (CC?) ranging from 0.006 to 1.16 ?g/L. The recoveries in blank blood were calculated by spiking experiments with a mixture of 18 PFASs and established between 70 and 126% for most of compounds. Isotopic dilution was carried out for quantification of selected analytes. In-house validation of this new approach was carried out according to the requirements in the 2002/657/EC Decision. Finally the good applicability of this new approach was proved by the analysis of 60 cord blood samples from two different Mediterranean cities, Barcelona (Spain) and Heraklion (Greece). Ions perfluorohexanesulfonate (PFHxS) and perfluorooctanesulfonate (PFOS) were found at highest concentration and the more frequently compounds were PFHxS, PFOS and perfluorooctanoic acid (PFOA). The newly developed method proved to be suitable for large-scale epidemiologic studies, and to the data on PFASs exposure during pregnancy. PMID:22789815

Llorca, Marta; Pérez, Francisca; Farré, Marinella; Agramunt, Sílvia; Kogevinas, Manolis; Barceló, Damià

2012-09-01

218

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 1.6ng/g for sediment samples and from 0.10 to 125ng/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

219

An overview of gallium nitride growth chemistry and its effect on reactor design: Application to a planetary radial-flow CVD system  

NASA Astrophysics Data System (ADS)

In this paper, gallium nitride (GaN) growth chemistry is characterized by two competing reaction pathways. An overview of GaN gas-phase and surface-phase chemistry is used to generate a comprehensive model for epitaxial GaN growth from the commonly used precursors, trimethylgallium ((CH 3) 3Ga) and ammonia (NH 3). The role of reactor geometry in controlling the selectivity among the competing reaction pathways is explored in the context of a planetary radial-flow CVD system. Finally, application of a geometrically based uniformity criterion is presented for film uniformity optimization.

Parikh, Rinku P.; Adomaitis, Raymond A.

2006-01-01

220

MEASUREMENT OF RADIONUCLIDES USING ION CHROMATOGRAPHY AND FLOW-CELL SCINTILLATION COUNTING WITH PULSE SHAPE DISCRIMINATION  

SciTech Connect

Radiological characterization and monitoring is an important component of environmental management activities throughout the Department of Energy complex. Gamma-ray spectroscopy is the technology most often used for the detection of radionuclides. However, radionuclides which cannot easily be detected by gamma-ray spectroscopy, such as pure beta emitters and transuranics, pose special problems because their quantification generally requires labor intensive radiochemical separations procedures that are time consuming and impractical for field applications. This project focused on a technology for measuring transuranics and pure beta emitters relatively quickly and has the potential of being field deployable. The technology combines ion exchange liquid chromatography and on-line alpha/beta pulse shape discriminating scintillation counting to produce simultaneous alpha and beta chromatograms. The basic instrumentation upon which the project was based was purchased in the early 1990's. In its original commercial form, the instrumentation was capable of separating select activation/fission products in ionic forms from relatively pure aqueous samples. We subsequently developed the capability of separating and detecting actinides (thorium, uranium, neptunium, plutonium, americium, and curium) in less than 30 minutes (Reboul, 1993) and realized that the potential time savings over traditional radiochemical methods for isolating some of these radionuclides was significant. However, at that time, the technique had only been used for radionuclide concentrations that were considerably above environmental levels and for aqueous samples of relatively high chemical purity. For the technique to be useful in environmental applications, development work was needed in lowering detection limits; to be useful in applications involving non-aqueous matrices such as soils and sludges or complex aqueous matrices such as those encountered in waste samples, development work was needed in sample preparation and processing. The general goal of this project was to address the issues mentioned above, and in so doing transform an interesting laboratory technique of limited applicability into a robust field instrument suitable for environmental restoration and waste management applications. The project consisted of the following tasks: (1) development of a low background, flow-cell detector, (2) identification of sample chemical and radiological interferences, (3) development of protocols for processing waste and/or environmental samples, and (4) integration and testing of the prototype system. The scope of work associated with these tasks has been completed and the report for Tasks 1-3 was submitted previously. Presented here are the results for Task 4.

R. A. Fjeld; T.A. DeVol; J.D. Leyba

2000-03-30

221

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

222

Application of a quasi-3D inviscid flow and boundary layer analysis to the hub-shroud contouring of a radial turbine  

NASA Technical Reports Server (NTRS)

Application of a quasi-3D approach to the aerodynamic analysis of several radial turbine configurations is described. The objective was to improve the rotor aerodynamic characteristics by hub-shroud contouring. The approach relies on available 2D inviscid methods coupled with boundary layer analysis to calculate profile, mixing, and endwall losses. Windage, tip clearance, incidence, and secondary flow losses are estimated from correlations. To eliminate separation along the hub and blade suction surfaces of a baseline rotor, the analysis was also applied to three alternate hub-shroud geometries. Emphasis was on elimination an inducer velocity overshoot as well as increasing hub velocities. While separation was never eliminated, the extent of the separated area was progressively reduced. Results are presented in terms of mid-channel and blade surface velocities; kinetic energy loss coefficients; and efficiency. The calculation demonstrates a first step for a systematic approach to radial turbine design that can be used to identify and control aerodynamic characteristics that ultimately determine heat transfer and component life. Experimentation will be required to assess the extent to which flow and boundary layer behavior were predicted correctly.

Civinskas, K. C.; Povinelli, L. A.

1984-01-01

223

Removal of nitrogen and organic matter in a radial-flow aerobic-anoxic immobilized biomass reactor used in the posttreatment of anaerobically treated effluent.  

PubMed

This work reports on the removal of organic matter and nitrogen in a radial-flow aerobic-anoxic immobilized biomass (RAIB) reactor fed with domestic sewage pretreated in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. Polyurethane foam was used as support material for biomass attachment in both reactors. In batch experiments, a first-order kinetic model with residual concentration represented the organic matter removal rate, whereas nitrogen conversion followed a pseudo-first-order reaction in series model, with kinetic constants k1 (ammonium to nitrite) and k2 (nitrite to nitrate) of 0.25 and 6.62 h(-1), respectively. The RAIB reactor was operated in continuous-flow mode and changes in the airflow rate and hydraulic retention time were found to interfere in the apparent kinetic constants to the nitritation (k1) and nitratation (k2). Nitrification and denitrification were achieved in the partially aerated RAIB reactor operating with hydraulic retention times of 3.3 h and 2.7 h in the aerobic and anoxic zones, respectively. Ethanol was added in the anoxic zone of the reactor to promote denitrification. The effluent flow of the RAIB reactor presented a COD of 52 mg l(-1), and concentrations of 2 mg N - NH4(+)1(-1), 1.24 mg N - N02(-)1(-1) and 3.46 mg N - N03(-)1(-1). PMID:18025567

Fazolo, Ajadir; Foresti, Eugenio; Zaiat, Marcelo

2007-07-01

224

Sequential Three-Phase Power Flow Calculation for Radial Distribution Systems via Three-Phase Z-Bus Distribution Factor  

Microsoft Academic Search

This paper aims to develop a sequential three-phase power flow program with three-phase ZBus distribution factor(TZBD) for power flow calculation. First, using monthly energy consumption of customers in a customer information system (CIS) and typical daily load pattern of customer classes, the quarter hourly loading profiles of distribution transformers were derived. The derived daily load curves are the loading database

Wei-Tzer Huang; Shiuan-Tai Chen

2009-01-01

225

Improvement in Accuracy of Ultrasonic Measurement of Transient Change in Viscoelasticity of Radial Arterial Wall Due to Flow-Mediated Dilation by Adaptive Low-Pass Filtering  

NASA Astrophysics Data System (ADS)

In our previous study, the stress--strain relationship of the radial arterial wall was measured and the viscoelasticity of the intima--media region was estimated from the stress--strain relationship. Furthermore, the transient change in viscoelasticity due to flow-mediated dilation (FMD) was estimated by the automated detection of wall boundaries. In the present study, the strain rate was adaptively filtered to improve the accuracy of viscoelasticity estimation by decreasing the high-frequency noise. Additionally, in a basic experiment, this method was validated using a silicone tube (simulating artery). In the basic experiment, the elasticity was estimated with a mean error of 1.2%. The elasticity measured at each beam position was highly reproducible among measurements, whereas there was a slight variation in measured elasticity among beams. Consequently, in in vivo measurements, the normalized mean square error (MSE) was clearly decreased. Additionally, the stress--strain relationship of the radial arterial wall was obtained and the viscoelasticity was estimated accurately. The inner small loop, which corresponds to the negative pressure wave caused by the closure of the aortic valve, can be observed using the adaptive low-pass filtering (LPF). Moreover, the transient changes in these parameters were similar to those in the previous study. These results show the potential of the proposed method for the thorough analysis of the transient change in viscoelasticity due to FMD.

Ikeshita, Kazuki; Hasegawa, Hideyuki; Kanai, Hiroshi

2012-07-01

226

Transient radial flow to a well in an unconfined aquifer. Part 1, An evaluation of some conceptual methods  

SciTech Connect

The analytic solutions of Boulton (1954) and Neuman (1972) for transient flow to a well in an unconfined aquifer are based on the assumption that the role of the unsaturated zone can be adequately accounted for by restricting attention to the release of water from the zone through which the water table moves. Both researchers mathematically treat this released water as a time-dependent source term. The differences between the models of Boulton and Neuman are that the former neglects vertical components of flow in the aquifer, but allows for an exponential process for the release of water as a function of time, whereas the latter assumes instantaneous release from storage, but accounts for vertical components of flow. Given this set of assumptions, we examine the applicability of these two methods using a general purpose numerical model through a process of verification extension and comparison. The issues addressed include: the role of well-bore storage in masking intermediate-time behavior, combined effects of exponential release as well as vertical flow, logic for vertical averaging of drawdowns, and the sensitivity of system response to the magnitude of specific yield. The issue of how good the assumptions of Boulton and Neuman are in the context of the general theory of unsaturated flow is addressed in part 2 of this two-part series of reports.

Narasimhan, T.N.; Zhu, Ming

1991-08-01

227

Radial lean direct injection burner  

SciTech Connect

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

228

Determination of thermal conductivities of Sn-Zn lead-free solder alloys with radial heat flow and Bridgman-type apparatus  

NASA Astrophysics Data System (ADS)

The variations of thermal conductivities of solid phases versus temperature for pure Sn, pure Zn and Sn-9 wt.% Zn, Sn-14 wt.% Zn, Sn-50 wt.% Zn, Sn-80 wt.% Zn binary alloys were measured with a radial heat flow apparatus. The thermal conductivity ratios of liquid phase to solid phase for the pure Sn, pure Zn and eutectic Sn-9 wt.% Zn alloy at their melting temperature are found with a Bridgman-type directional solidification apparatus. Thus, the thermal conductivities of liquid phases for pure Sn, pure Zn and eutectic Sn-9 wt.% Zn binary alloy at their melting temperature were evaluated by using the values of solid phase thermal conductivities and the thermal conductivity ratios of liquid phase to solid phase.

Meydaneri, Fatma; Saatçi, Buket; Gündüz, Mehmet; Özdemir, Mehmet

2013-11-01

229

The Influence of Stop-Flow on Band Broadening of Peptides in Micro-Liquid Chromatography  

Microsoft Academic Search

Stop-flow techniques are occasionally needed in combinations of LC-NMR and LC-MS. During the interval when there is no flow\\u000a on the column, axial diffusion of components not yet eluted can be expected to take place. In this paper the size of the band\\u000a broadening which is caused by diffusion during stop-flow has been determined for two peptides on reversed-phase packed

B. Q. Tran; E. Lundanes; T. Greibrokk

2006-01-01

230

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...

231

Experimental analysis of the swirling flow in a Francis turbine draft tube: Focus on radial velocity component determination  

Microsoft Academic Search

The draft tube of a hydraulic turbine is the component where the flow exiting the runner is decelerated, thereby converting the excess of kinetic energy into static pressure. In the case of machine refurbishment of an existing power plant, most of the time only the runner and the guide vanes are currently modified. For financial and safety reasons, the spiral

Sylvain Tridon; Stéphane Barre; Gabriel Dan Ciocan; Laurent Tomas

2010-01-01

232

Lateral flow microarrays: a novel platform for rapid nucleic acid detection based on miniaturized lateral flow chromatography  

PubMed Central

Widely used nucleic acid assays are poorly suited for field deployment where access to laboratory instrumentation is limited or unavailable. The need for field deployable nucleic acid detection demands inexpensive, facile systems without sacrificing information capacity or sensitivity. Here we describe a novel microarray platform capable of rapid, sensitive nucleic acid detection without specialized instrumentation. The approach is based on a miniaturized lateral flow device that makes use of hybridization-mediated target capture. The miniaturization of lateral flow nucleic acid detection provides multiple advantages over traditional lateral flow devices. Ten-microliter sample volumes reduce reagent consumption and yield analyte detection times, excluding sample preparation and amplification, of <120?s while providing sub-femtomole sensitivity. Moreover, the use of microarray technology increases the potential information capacity of lateral flow. Coupled with a hybridization-based detection scheme, the lateral flow microarray (LFM) enables sequence-specific detection, opening the door to highly multiplexed implementations for broad-range assays well suited for point-of-care and other field applications. The LFM system is demonstrated using an isothermal amplification strategy for detection of Bacillus anthracis, the etiologic agent of anthrax. RNA from as few as two B. anthracis cells was detected without thermocycling hardware or fluorescence detection systems.

Carter, Darren J.; Cary, R. Bruce

2007-01-01

233

Travel time distributions under convergent radial flow in heterogeneous formations: Insight from the analytical solution of a stratified model  

NASA Astrophysics Data System (ADS)

We analyze conservative solute transport under convergent flow to a well in perfectly stratified porous media, in which the hydraulic conductivity is treated as a random spatial function along the vertical direction (K(z)). The stratified model provides a rare exception of an exact analytical solution of travel time distributions in the proximity of pumping wells, and it is used here to obtain insights about ergodic and nonergodic transport conditions under nonuniform flow conditions. In addition, it provides a benchmark for numerical models aiming to correctly reproduce convergent flow transport in heterogeneous media, such as indicating the minimum number of layers required to obtain ergodic travel time distributions using only one model realization. The model provides important insights about the shape of the depth-integrated concentrations over time measured at the well (breakthrough curves, BTCs), which are usually applied to obtain transport parameters of the subsurface. It can be applied to any degree of system's heterogeneity and using either resident or flux-weighted injection modes. It can be built using different probabilistic distributions of K. In our analysis, we consider a log-normal K distribution, and the results indicate that, especially for highly heterogeneous systems, described by the log-K variance (?Y2), the minimum number of layers required for from one model simulation to reproduce ergodic travel time distributions can be prohibitively high, e.g., above 106 for ?Y2=8 considering flux-weighted injections. This issue poses serious concerns for numerical applications aiming to simulate transport in the proximity of pumping wells. In addition, this simple solution confirms that stratification can lead BTCs to display strong preferential flow and persistent, power-law-like late-time tailing. Since the latter are common phenomenological macroscale evidences of other microscale hydrodynamic processes than pure advection (e.g., mass-transfer), caution must be taken when inferring aquifer properties controlling the anomalous transport dynamics in heterogeneous media from BTCs fitting.

Pedretti, Daniele; Fiori, Aldo

2013-10-01

234

A flow-through microsampling device applied to an ion-exchange chromatography system.  

PubMed

A flow-through microsampling device that can be inserted in the column elution flow line of a chromatographic system has been developed. A sample drop (volume 2.2 nl) is ejected when a voltage pulse is applied to a piezo-electric transducer. The drops can be ejected with up to 70 Hz frequency, giving a sample flow range of 0-9 microliters/min. Samples were collected on a moving agarose surface during elution of freshly prepared human serum. The precipitate pattern obtained after immunoelectrophoresis is similar to what would be obtained in a fused rocket electrophoresis of multiple samples from a fraction collector. PMID:8258638

Nilsson, J; Szecsi, P; Schafer-Nielsen, C

1993-10-01

235

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

236

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”.

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

2010-01-01

237

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

Microsoft Academic Search

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

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

2012-01-01

238

High-speed analysis of residual solvents by flow-modulation gas chromatography.  

PubMed

High-speed gas chromatographic (GC) separation of residual solvents in pharmaceutical preparations, using a flow-modulation technique, is described. These volatile compounds are separated on a series-coupled (tandem) column ensemble consisting of a polyethylene glycol column and a trifluoropropylmethyl/dimethylpolysiloxane column. This column ensemble is operated in stop-flow mode to enhance, or "tune", the separation. A valve between the junction point of the tandem column ensemble and a source of carrier gas at a pressure above the GC inlet pressure is opened for intervals of 2-8 s. This stops or slightly reverses the flow of carrier gas in the first column. Stop-flow pulses are used to increase the separation of target analytes that overlap in the total ensemble chromatogram, compared to non-stop-flow, or conventional, operation. All 36 target compounds, based on ICH Classes I and II residual solvent lists, are resolved in 12 min using the stop-flow technique and a single chromatographic analysis. PMID:14971486

Wittrig, Rebecca E; Dorman, Frank L; English, Christopher M; Sacks, Richard D

2004-02-20

239

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

240

The membrane dialysis bioreactor with integrated radial-flow fixed bed--a new approach for continuous cultivation of animal cells.  

PubMed

A hybridoma cell was cultivated continuously in a membrane dialysis bioreactor with an integrated radial-flow fixed bed consisting of porous Siran carriers over a period of 6 weeks. Antibodies accumulated to an average of 100 mg l-1, approx. 10 times more than in fixed bed cultures without dialysis membrane. Serum costs could be reduced about 85% due to an appropriate feeding strategy. Siran carriers with 3-5 mm diameter showed an advantage compared to those with 1-2 mm diameter. For the 3-5 mm carrier the specific glucose uptake rate and the MAb production rate were constant, if the velocity was between 0.09 mm s-1 and 0.75 mm s-1. At higher velocities cells are washed out of the bed. Furthermore antibody consistency and cell stability were verified in long-term cultivations over a period of 96 days. From an estimation of the antibody concentration reachable with the reactor concept under optimal conditions a concentration 45 times higher compared to axial-flow fixed bed reactors and 11 times higher compared to stirred tank reactors can be expected. PMID:1369181

Bohmann, A; Pörtner, R; Schmieding, J; Kasche, V; Märkl, H

1992-01-01

241

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

NASA Technical Reports Server (NTRS)

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 turbine flows were developed and demonstrated. The ability to use the cobra probes to obtain static pressure and, therefore, velocity had to be verified; insertion techniques had to be established for the fragile hot-film probes; and a seeding method had to be established for the laser velocimetry. Once the measurement techniques were established, turbine inlet and exit velocity profiles, temperature profiles, pressure profiles, turbulence intensities, and boundary layer thicknesses were measured at the turbine design point. The blockage effect due to the model inlet and exit total pressure and total temperature rakes on the turbine performance was also studied. A small range of off-design points were run to obtain the profiles and to verify the rake blockage effects off-design. Finally, a range of different Reynolds numbers were run to study the effect of Reynolds number on the various measurements.

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

1995-01-01

242

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  

Microsoft Academic Search

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

Dieter Zimmer; Volker Pickard; Waldemar Czembor; Christoph Müller

1999-01-01

243

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

244

Distributed generation modeling for power flow studies and a three-phase unbalanced power flow solution for radial distribution systems considering distributed generation  

Microsoft Academic Search

Distributed generations (DGs) are generally modeled as PV or PQ nodes in power flow studies (PFSs) for distribution system. Determining a suitable model for each DG unit requires knowing the DG operation and the type of its connection to the grid (direct or indirect). In this respect, this paper offers a helpful list of DG models for PFSs. Moreover, an

S. M. Moghaddas-Tafreshi; Elahe Mashhour

2009-01-01

245

Direct liquid sample introduction for flow injection analysis and liquid chromatography with inductively coupled argon plasma spectrometric detection  

SciTech Connect

The coupling of flow injection analysis (FIA) or high-performance liquid chromatography (HPLC) techniques to inductively coupled plasma atomic emission spectrometry (ICP-AES) offers new and attractive approaches for the determination of elemental concentrations in a wide variety of sample matrices. One of the most attractive features that FIA offers is a rapid and precise means of automating sample introduction into an ICP for simultaneous, multielement analysis at the trace, minor, and major constituent level with minimal sample consumption. The utilization of the ICP as a detector for HPLC retains most of the advantages of FIA-ICP, while providing the analyst with a powerful and versatile means of compound separation. This added dimension becomes particularly important when metal speciation is of primary interest, rather than total metal content. To date, the coupling of FIA and HPLC to the ICP has only been accomplished using conventional cross-flow, concentric, or Babington-type pneumatic nebulizers. Limits of detection under these conditions have generally been observed to be poorer when compared to conventional continuous sample flow conditions. These limitations have been attributed to the large dead-volume and the sample losses associated with conventional nebulizers and band broadening of eluents from FIA transfer tubing or HPLC columns prior to entering the nebulizer unit. In an effort to resolve these difficulties, a microconcentric nebulizer has been developed which is inserted directly into the tip of a conventional sample introduction tube of an ICP torch. Preliminary data on the potential utility of direct liquid sample introduction into the ICP are presented. 12 references, 6 figures, 1 table.

Lawrence, K.E.; Rice, G.W.; Fassel, V.A.

1984-02-01

246

Performance of a membrane-dialysis bioreactor with a radial-flow fixed bed for the cultivation of a hybridoma cell line.  

PubMed

A bioreactor system for the continuous cultivation of animal cells with a high potential for scale-up is presented. This reactor system consists of radial-flow fixed-bed units coupled with a dialysis module The dialysis membrane enables the supply of low-molecular-weight nutrients and removal of toxic metabolites, while high-molecular-weight nutrients and products (e.g., monoclonal antibodies) are retained and accumulated. This concept was investigated on the laboratory scale in a bioreactor with an integrated dialysis membrane. The efficiency of the reactor system and the reproducibility of the cell activity (hybridoma cells) under certain process conditions could be demonstrated in fermentations up to 77 days. Based on model calculations, an optimized fermentation strategy was formulated and experimentally confirmed. Compared to chemostat cultures with suspended cells, a ten-times higher mAb concentration (383 mg1(-1)) could be obtained. The highest volumetric specific mAb production rate determined was 6.1 mg mAb (1 fixed bed)-1h-1. PMID:7576545

Bohmann, A; Pörtner, R; Märkl, H

1995-10-01

247

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

248

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

249

A plant kinetic study of alcoholic fermentation using reversed-flow gas chromatography  

SciTech Connect

The reversed-flow gas chromatographic sampling technique is used to study the kinetics of alcoholic fermentation in a factory in conjunction with measurements of suspended particles in the fermenting medium. It was found that the overall process consists of four phases which have different first-order rate constants during ethanol formation. The second phase is the slowest with its rate constant being 4.3 and 13 times smaller than that of the first and third phases, respectively. There is also a decrease of suspended particles during the second phase. These results show that there is the possibility of increasing the rate constant during this phase, thereby increasing the overall production rate of ethanol significantly and thus lowering its cost of production.

Economopoulos, N.; Athanassopoulos, N. (B.G. Spiliopoulos Distilleri S.A., Patras (Greece)); Katsanos, N.A.; Karaiskakis, G.; Agathonos, P.; Vassilakos, Ch. (Univ. of Patras (Greece))

1992-12-01

250

Sap flow measurements combining sap-flux density radial profiles with punctual sap-flux density measurements in oak trees (Quercus ilex and Quercus pyrenaica) - water-use implications in a water-limited savanna-  

NASA Astrophysics Data System (ADS)

Sap flow measurement is a key aspect for understanding how plants use water and their impacts on the ecosystems. A variety of sensors have been developed to measure sap flow, each one with its unique characteristics. When the aim of a research is to have accurate tree water use calculations, with high temporal and spatial resolution (i.e. scaled), a sensor with high accuracy, high measurement efficiency, low signal-to-noise ratio and low price is ideal, but such has not been developed yet. Granier's thermal dissipation probes (TDP) have been widely used in many studies and various environmental conditions because of its simplicity, reliability, efficiency and low cost. However, it has two major flaws when is used in semi-arid environments and broad-stem tree species: it is often affected by high natural thermal gradients (NTG), which distorts the measurements, and it cannot measure the radial variability of sap-flux density in trees with sapwood thicker than two centimeters. The new, multi point heat field deformation sensor (HFD) is theoretically not affected by NTG, and it can measure the radial variability of the sap flow at different depths. However, its high cost is a serious limitation when simultaneous measurements are required in several trees (e.g. catchment-scale studies). The underlying challenge is to develop a monitoring schema in which HFD and TDP are combined to satisfy the needs of measurement efficiency and accuracy in water accounting. To assess the level of agreement between TDP and HFD methods in quantifying sap flow rates and temporal patterns on Quercus ilex (Q.i ) and Quercus pyrenaica trees (Q.p.), three measurement schemas: standard TDP, TDP-NTG-corrected and HFD were compared in dry season at the semi-arid Sardon area, near Salamanca in Spain in the period from June to September 2009. To correct TDP measurements with regard to radial sap flow variability, a radial sap flux density correction factor was applied and tested by adjusting TDP measurements using the HFD-measured radial profiles. The standard TDP daily mean of sap-flux density was 95% higher than the 2cm equivalent of the HFD for Q. ilex and 70% higher for Q. pyrenaica. NTG-corrected TDP daily mean of sap-flux density was 34% higher than HFD for Q. ilex and 47% lower for Q. pyrenaica. Regarding sap flow measurements, the standard TDP sap flow was 81% higher than HFD sap flow for Q. ilex and 297% for Q. pyrenaica. The NTG-corrected TDP sap flow was 24% higher than HFD sap flow for Q. ilex and 23% for Q. pyrenaica. The radial correction, for TDP-NTG-corrected sap-flux density, produced sap-flow measurements in well agreement with HFD, just slightly lower (-3% Q.i. and -4% Q.p.). The TDP-HFD sap flow data acquired in dry season over the savanna type of sparsely distributed oak trees (Q. ilex & Q. pyrenaica) showed that the TDP method must be corrected for NTG and for radial variability of sap flux density in trees with sapwood thicker than 2 cm. If such corrections are not taken into consideration, the amount of accounted water used by the trees is prone to overestimation, especially for Quercus pyrenaica. The obtained results indicate also that the combination of HFD and TDP leads to an efficient and accurate operational sap flow measurement schema that is currently in the optimization stage.

Reyes, J. Leonardo; Lubczynski1, Maciek W.

2010-05-01

251

Automated analysis of perfluorinated compounds in human hair and urine samples by turbulent flow chromatography coupled to tandem mass spectrometry.  

PubMed

Perfluorinated compounds (PFCs) are ubiquitous contaminants of humans and animals worldwide. PFCs are bioaccumulated because of their affinity for proteins. It has been shown they could have a variety of toxicological effects and cause damage to human health, emphasizing the need for sensitive and robust analytical methods to assess their bioaccumulation in humans. In this paper we report the development and validation of an analytical method for analysis of PFCs in the non-invasive human matrices hair and urine. The method is based on rapid and simple sample pre-treatment followed by online turbulent flow liquid chromatography and tandem mass spectrometry (TFC-LC-MS-MS) for analysis of 21 PFCs. The method was validated for both matrices. Percentage recovery was between 60 and 105 for most compounds in both matrices. Limits of quantification ranged from 0.1 to 9 ng mL(-1) in urine and from 0.04 to 13.4 in hair. The good performance of the method was proved by investigating the presence of selected PFCs in 24 hair and 30 urine samples from different donors living in Barcelona (NE Spain). The results were indicative of bioaccumulation of these compounds in both types of sample. PFOS and PFOA were most frequently detected in hair and PFBA in urine. PMID:22227745

Perez, Francisca; Llorca, Marta; Farré, Marinella; Barceló, Damià

2012-03-01

252

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

253

Efficient separations of intact proteins using slip-flow with nano-liquid chromatography-mass spectrometry.  

PubMed

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

Wu, Zhen; Wei, Bingchuan; Zhang, Ximo; Wirth, Mary J

2014-02-01

254

Development of a liquid chromatography-tandem mass spectrometry method for plasma-free metanephrines with ion-pairing turbulent flow online extraction.  

PubMed

Liquid chromatography-tandem mass spectrometry has become the preferred technology to measure unconjugated metanephrine and normetanephrine in plasma because of its high sensitivity and specificity over immunoassay and gas chromatography-mass spectrometry. In our earlier study, plasma metanephrines were extracted with offline ion-pairing solid-phase extraction and quantified by liquid chromatography-tandem mass spectrometry with porous graphitic carbon column based chromatography. In this study, we aim to automate the sample preparation with turbulent flow online extraction technology and maintain or improve the analytical performance previously achieved from the offline approach. The online extraction was done with a mixed-mode cation exchange turbulent flow chromatography column assisted with ion-pairing reagent and porous graphitic column was used for chromatographic separation. The total online extraction and analytical LC runtime was 12 min. This method was linear from 6.3 to 455.4 pg/mL for metanephrine; 12.6 to 954.5 pg/mL for normetanephrine with an accuracy of 80.6% to 93.5% and 80.9% to 101.7%, respectively. The lower limit of quantitation was 6.3 pg/mL for metanephrine and 12.6 pg/mL for normetanephrine. Inter-assay and intra-assay precision for metanephrine and normetanephrine at low and high concentration levels ranged from 2.0% to 10.5%. In conclusion, we have developed a fast and sensitive automated online turbulent flow extraction method for the quantitative analysis of plasma metanephrines. Ion-pairing reagent was necessary for the success of this method. PMID:22349327

He, Xiang; Kozak, Marta

2012-03-01

255

Measurement of radionuclides using ion chromatography and flow-cell scintillation counting with pulse shape discrimination  

SciTech Connect

Principal conclusions are: CsI(Tl) provides sufficient pulse shape discrimination for use in the flow-cell detector. However, an improved method of coating is needed to extend the useful life of a detection cell. Of the activation/fission products investigated, only the co-elution of {sup 137}Cs and {sup 63}Ni produced a radiological interference. Tritium (and presumably other non-ionic radioisotopes) can be separated during the loading of the solution onto the pre- concentration column. Natural U (and/or decay products) produced a radiological interference with {sup 90}Sr. This is a potential problem. No potential radiological interferences were observed with {sup 223}Th. Chemical interferences were observed to some degree for all the chemicals tested except for the chloride solutions, NaCl and KCl, and the sulfate solution, Na{sub 2}SO{sub 4}. The specific interference effects were decreased detection efficiencies and changes in peak elution times. The NEL`s (non-observable effects loadings) are tentative targets for development of sample processing protocols, which is the next phase of the work.

DeVol, T.A.; Fjeld, R.A.; Roane, J.E. [Clemson Univ., SC (United States). Dept. of Environmental Systems Engineering; Leyba, J.D. [Westinghouse Savannah River Co., Aiken, SC (United States); Branton, S.D. [Nuclear Regulatory Commission, Washington, DC (United States)

1996-12-31

256

Discovery of candidate phospholipid biomarkers in human lipoproteins with coronary artery disease by flow field-flow fractionation and nanoflow liquid chromatography-tandem mass spectrometry.  

PubMed

In this study, an analytical method is demonstrated to identify and develop potential phospholipid (PL) biomarkers of high density lipoprotein (HDL) and low density lipoprotein (LDL) in plasma from individuals with coronary artery disease (CAD) by employing a combination of off-line multiplexed hollow fiber flow field-flow fractionation (MxHF5) and nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS-MS). HDL and LDL particles of human plasma were sorted by size at a semi-preparative scale using MxHF5, after which PL extracts of each lipoprotein fraction were qualitatively and quantitatively analyzed by nLC-ESI-MS-MS. Experiments were performed using plasma samples from 10 CAD patients and 10 controls. Quantitative analysis of the 93 PL species identified yielded a selection of 19 species from HDL fractions and 10 from LDL fractions exhibiting at least a five fold change in average concentration in CAD patients. Among the selected species, only a few were found exclusively in patient HDL fractions (18:3-LPA and 20:2/16:0-PG), control HDL fractions (16:0/16:1-PC, 20:1/20:4-PE, and 16:1-LPA), and control LDL fractions (16:0/22:3-PG). Moreover, 16:1/18:2-PC was detected from both HDL and LDL fractions of controls but disappeared in CAD patients. Although the typical change in lipoproteins for CAD is well known, with decreased levels of HDLs and reduced LDL particle size, the current study provides fundamental information on the molecular level of lipoprotein variation which can be utilized for diagnostic and therapeutic tracking. PMID:23195705

Byeon, Seul Kee; Lee, Ju Yong; Lim, Sangsoo; Choi, Donghoon; Moon, Myeong Hee

2012-12-28

257

Radial cold trap  

DOEpatents

The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

Grundy, Brian R. (Greensburg, PA)

1981-01-01

258

Radial cold trap  

DOEpatents

The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

Grundy, B.R.

1981-09-29

259

Analysis of major ovine milk proteins by reversed-phase high-performance liquid chromatography and flow injection analysis with electrospray ionization mass spectrometry  

Microsoft Academic Search

Ovine milk proteins were analyzed both by coupling HPLC and electrospray ionization mass spectrometry (ESI-MS) and by flow injection analysis and ESI-MS detection after separation and collection of fractions from gel permeation chromatography. These methods resolved the four ovine caseins and whey proteins and made it possible to study the complexity of these proteins associated with genetic polymorphism, post-translational changes

Antonio-José Trujillo; Isidre Casals; Buenaventura Guamis

2000-01-01

260

On-line coupling of flow injection displacement sorption preconcentration to high-performance liquid chromatography for speciation analysis of mercury in seafood  

Microsoft Academic Search

A simple and cost-effective method for speciation analysis of trace mercury in seafood was developed by on-line coupling flow injection microcolumn displacement sorption preconcentration to high-performance liquid chromatography (HPLC) with UV detection. The methodology involved the presorption of the Cu-PDC (pyrrolidine dithiocarbamate) chelate onto a microcolumn packed with a cigarette filter sorbent, simultaneous preconcentration of Hg(II), methylmercury (MeHg), ethylmercury (EtHg),

Li-Ming Dong; Xiu-Ping Yan; Yan Li; Yan Jiang; Shan-Wei Wang; Dong-Qing Jiang

2004-01-01

261

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

262

Separation of five oligostilbenes from Vitis amurensis by flow-rate gradient high-performance counter-current chromatography.  

PubMed

A rapid and efficient high-performance counter-current chromatography (HPCCC) method was developed to separate five oligostilbenes from the roots of Vitis amurensis. An n-hexane/ethyl acetate/methanol/water system (4:8:4:10, v/v/v/v) was selected as an optimal two-phase solvent system of which the upper phase was used as the stationary phase and the lower phase was used as the mobile one. Partition coefficient values for the target compounds under these optimized conditions were 0.28 (1, ampleosin A), 7.12 (2, (+)-g-viniferin), 2.26 (3, vitisin A), 5.38 (4, wilsonol C), and 11.23 (5, vitisin B). Flow-rate gradient HPCCC (4 mL/min in 0-70 min, 8 mL/min in 70-250 min) was applied to isolate the target compounds in as high purity as possible within the shortest possible run time. Under these conditions, ampelopsin A (12.1 mg), (+)-g-viniferin (10.4 mg), vitisin A (2.8 mg), wilsonol C (3.2 mg), and vitisin B (37 mg) were isolated with >95% purity from 150 mg of enriched oligostilbene extract. Although the KD of the last eluted compound, vitisin B (KD = 11.23), was relatively large, it was eluted in 115-145 min using the two-phase solvent system. This study shows that HPCCC is an efficient tool for the isolation and purification of natural products. PMID:24167107

Ko, Jaeyoung; Choi, Janggyoo; Bae, Soo Kyung; Kim, Jinwoong; Yoon, Kee Dong

2013-12-01

263

Chemiluminometric enzyme-linked immunosorbent assays (ELISA)-on-a-chip biosensor based on cross-flow chromatography.  

PubMed

A chemiluminometric biosensor system for point-of-care testing has been developed using an immuno-chromatographic assay combined with an enzyme (e.g., horseradish peroxidase) tracer that produces a light signal measurable on a simple detector. Cross-flow chromatography, a method previously investigated by our laboratory, was utilized in order to accomplish sequential antigen-antibody binding and signal generation. This enzyme-linked immunosorbent assay (ELISA) was effectively carried out on a plastic chip that was redesigned to simplify the fabrication process. To enhance the sensitivity, biotin-streptavidin capture technology was employed in preparing an immuno-strip that was then incorporated onto the chip in order to generate the ELISA-on-a-chip (EOC) biosensor. Samples containing cardiac troponin I (cTnI) were analyzed using the EOC. A chemiluminescent signal proportional to the analyte concentration was produced by adding a luminogenic substrate to the tracer enzyme complexed with the analyte on the chip. The luminescent signal was detected in a dark chamber mounted with a cooled charge-coupled device and the signal was converted to optical density for quantification. This EOC biosensor system was capable of detecting cTnI present in serum at concentrations as low as 0.027 ng mL(-1), 30 times lower than those measured using the conventional rapid test kit with colloidal gold as the tracer. In addition, the final data was acquired within 30s after the addition of the enzyme substrate, which was faster than the detection time required when using a colorimetric substrate with the same tracer enzyme. PMID:19110101

Cho, Il-Hoon; Paek, Eui-Hwan; Kim, Young-Kee; Kim, Joo-Ho; Paek, Se-Hwan

2009-01-26

264

Optimal conductor selection for radial distribution systems  

Microsoft Academic Search

In this paper, an algorithm is proposed for selecting the optimum size of conductors of feeder sigments of radial distribution networks. The optimal size of conductor determined by load flow method is applied to the optimal distance radial distribution network. The conductor, which is determined by the proposed method, will maximize the total saving in cost of conducting material and

S Sivanagaraju; N Sreenivasulu; M Vijayakumar; T Ramana

2002-01-01

265

Distributed spot pricing in radial distribution systems  

Microsoft Academic Search

Spot pricing is a method for pricing electricity that maximizes the economic efficiency of the power system. The authors derive an expression for the spot prices in a radial distribution system, in terms of system quantities such as power line flows. The system's radial structure leads to simplified spot price expressions. They do not assume that all the problem data

L. Murphy; R. J. Kaye; F. F. Wu

1994-01-01

266

On radial geodesic forcing of zonal modes  

NASA Astrophysics Data System (ADS)

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.

2011-07-01

267

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

268

Simultaneous clarification of Escherichia coli culture and purification of extracellularly produced penicillin G acylase using tangential flow filtration and anion-exchange membrane chromatography (TFF-AEMC).  

PubMed

Downstream purification often represents the most cost-intensive step in the manufacturing of recombinant proteins since conventional purification processes are lengthy, technically complicated, and time-consuming. To address this issue, herein we demonstrated the simultaneous clarification and purification of the extracellularly produced recombinant protein by Escherichia coli using an integrated system of tangential flow filtration and anion exchange membrane chromatography (TFF-AEMC). After cultivation in a bench-top bioreactor with 1L working volume using the developed host/vector system for high-level expression and effective secretion of recombinant penicillin G acylase (PAC), the whole culture broth was applied directly to the established system. One-step purification of recombinant PAC was achieved based on the dual nature of membrane chromatography (i.e. microfiltration-sized pores and anion-exchange chemistry) and cross-flow operations. Most contaminant proteins in the extracellular medium were captured by the anion-exchange membrane and cells remained in the retentate, whereas extracellular PAC was purified and collected in the filtrate. The batch time for both cultivation and purification was less than 24h and recombinant PAC with high purity (19 U/mg), yield (72% recovery), and productivity (41 mg of purified PAC per liter of culture) was obtained. Due to the nature of the non-selective protein secretion system and the versatility of ion-exchange membrane chromatography, the developed system can be widely applied for effective production and purification of recombinant proteins. PMID:22709629

Orr, Valerie; Scharer, Jeno; Moo-Young, Murray; Honeyman, C Howie; Fenner, Drew; Crossley, Lisa; Suen, Shing-Yi; Chou, C Perry

2012-07-01

269

Flow mechanism of Forchheimer's cubic equation in high-velocity radial gas flow through porous media. [High-velocity, high-pressure gas flow through porous media near the wellbore  

Microsoft Academic Search

Until recently, the visco-inertial flow equation, which is an adaptation of Forchheimer's quadratic equation, has been used to describe gas flow behavior at higher flow rates and pressures. The inability of this equation, in some cases, to fully describe high-velocity, high-pressure gas flow behavior, especially around the well bore, led to the consideration of other empirical equations. In this paper,

Ezeudembah; P. M. Dranchuk

1982-01-01

270

Rapid and semiautomated method for the analysis of veterinary drug residues in honey based on turbulent-flow liquid chromatography coupled to ultrahigh-performance liquid chromatography-Orbitrap mass spectrometry (TFC-UHPLC-Orbitrap-MS).  

PubMed

A simple and rapid method is described for the determination of veterinary drug (VD) residues in honey samples using turbulent flow chromatography coupled to ultrahigh-performance liquid chromatography-Orbitrap mass spectrometry (TFC-UHPLC-Orbitrap-MS). Honey samples were diluted with an aqueous solution of Na(2)EDTA (0.1 M). Then, they were injected into the chromatographic system including a TFC column. Afterward, the analytes were transferred to an UHPLC analytical column, where they were determined by UHPLC-Orbitrap-MS. Mean recoveries were obtained at three concentration levels (5, 10, and 50 ?g/kg), ranging from 68 to 121% for most compounds. Repeatability (intraday precision) and interday precision (expressed as relative standard deviation, RSD) were <25% for most compounds. Limits of quantification (LOQs) ranged from 5 to 50 ?g/kg and limits of identification (LOIs) from 0.1 to 50 ?g/kg. The developed method was applied in honey samples, and it was fast and nonlaborious. PMID:23282367

Aguilera-Luiz, María M; Romero-González, Roberto; Plaza-Bolaños, Patricia; Vidal, José L Martínez; Frenich, Antonia Garrido

2013-01-30

271

Radial Zernike Moment Invariants  

Microsoft Academic Search

Radial Zernike moment invariants are special case from the complex Zernike moment invariants. The radial and angular dependence of Zernike moments is naturally separable which makes them very suitable features for achieving rotational invariances. The major drawback of Zernike moments in general and radial Zernike moments in particular is the scale and translation invariance can only be achieved by relating

Saeid Belkasim; E. Hassan; T. Obeidi

2004-01-01

272

Direct analysis of the mushroom poisons ?- and ?-amanitin in human urine using a novel on-line turbulent flow chromatography mode coupled to liquid chromatography-high resolution-mass spectrometry/mass spectrometry.  

PubMed

Poisonings with Amanita phalloides toxins require fast diagnosis in order to avoid expensive and unnecessary therapies. Initial clinical assessment in combination with urinary amanitin analysis is necessary for a definite diagnosis. Therefore, a simple, fast, and robust method was developed for reliable detection of ?- and ?-amanitin as well as for fully validated quantification of ?-amanitin in human urine. After simple dilution and centrifugation of the urine sample, a fast on-line extraction using a Transcend TLX-II system based on turbulent flow chromatography (TurboFlow) was established. A new TurboFlow mode was introduced, the pseudo quick elute mode (PQEM), which had more options for method optimization than the generic quick elute mode (QEM). It allowed running several modes in one valve arrangement. The PQEM showed better practicability in routine and emergency analysis than the previously used methods. After extraction, the fast 15min LC-high resolution (HR)-MS/MS analysis allowed reliable identification of ?- and ?-amanitin based on fragments identified using so-called HR pseudo MS(3) experiments. According to international recommendations, the requirements for full validation including the parameters selectivity, calibration, accuracy, precision, recovery, matrix effects, and stability were fulfilled for ?-amanitin. The method was successfully applied to the analysis of authentic urine samples containing amatoxins. In conclusion, this method allowed the determination of amatoxins using the novel PQEM in a faster, robust, and more reliable way than existing methods, making it suitable for daily routine and especially emergency toxicological analysis. PMID:24342531

Helfer, Andreas G; Meyer, Markus R; Michely, Julian A; Maurer, Hans H

2014-01-17

273

Novel Integration Radial and Axial Magnetic Bearing  

NASA Technical Reports Server (NTRS)

Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

Blumenstock, Kenneth; Brown, Gary

2000-01-01

274

Comparative study of differential flow and cryogenic modulators comprehensive two-dimensional gas chromatography systems for the detailed analysis of light cycle oil.  

PubMed

The modulator is the key point of comprehensive two-dimensional gas chromatography (GC×GC). This interface ensures the sampling and transfer of the sample from the first to the second dimension. Many systems based on different principles have been developed. However, to our knowledge, almost only cryogenic modulators are used in the petroleum industry. Nevertheless cryogenic fluids represent some disadvantages in term of safety, cost and time consuming. This paper reports a comparative study between differential flow and cryogenic liquid modulators for the detailed analysis of hydrocarbons in middle distillates type light cycle oil (LCO). Optimization of geometrical dimensions of a set of columns was carried out on the differential flow modulator system in order to reproduce the quality of separation of cryogenic modulation. Then a comparative study was investigated on sensibility and resolution (separation space and peak capacity) between the two systems. PMID:20933237

Semard, G; Gouin, C; Bourdet, J; Bord, N; Livadaris, V

2011-05-27

275

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.

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

2011-01-01

276

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

277

On-line coupling of macroporous resin column chromatography with direct analysis in real time mass spectrometry utilizing a surface flowing mode sample holder.  

PubMed

A surface flowing mode sample holder was designed as an alternative sampling strategy for direct analysis in real time mass spectrometry (DART-MS). With the sample holder, the on-line coupling of macroporous resin column chromatography with DART-MS was explored and the new system was employed to monitor the column chromatography elution process of Panax notoginseng. The effluent from macroporous resin column was first diluted and mixed with a derivatization reagent on-line, and the mixture was then directly transferred into the ionization region of DART-MS by the sample holder. Notoginsenosides were methylated and ionized in a metastable helium gas stream, and was introduced into MS for detection. The on-line system showed reasonable repeatability with a relative standard deviation of 12.3% for the peak area. Three notoginsenosides, i.e. notoginsenoside R1, ginsenoside Rb1 and ginsenoside Rg1, were simultaneously determined during the eluting process. The alteration of the chemical composition in the effluent was accurately identified in 9 min, agreeing well with the off-line analysis. The presented technique is more convenient compared to the traditional UPLC method. These results suggest that the surface flowing mode DART-MS has a good potential for the on-line process monitoring in the pharmaceutical industry. PMID:24456593

Zeng, Shanshan; Wang, Lu; Chen, Teng; Qu, Haibin

2014-02-01

278

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

279

Radial arm strike rail  

SciTech Connect

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

280

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

281

Off-Design Performance of Radial-Inflow Turbines  

NASA Technical Reports Server (NTRS)

Computer code determines rotor exit flow from hub to tip. RTOD (Radial Turbine Off-Design), computes off-design performance of radial turbine by modeling flow with stator viscous and trailing-edge losses, and with vaneless space loss between stator and rotor, and with rotor incidence, viscous, clearance, trailing-edge, and disk friction losses.

Meitner, P. L.; Glassman, A. J.

1986-01-01

282

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

2011-05-23

283

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.

2011-04-13

284

Optical properties of axial-illumination flow cells for simultaneous absorbance-fluorescence detection in micro liquid chromatography  

Microsoft Academic Search

Simultaneous measurements of absorbance and fluorescence are possible with axial-illuminated flow cells, fashioned with a unique bend geometry. The optical properties of these flow cells have been studied. Effects of variations in lumen refractive index, capillary wall thickness and physical pathlength have been examined. A theoretical understanding of the various light propagation modes and of light intensity distributions in these

Ahmad A. Abbas; Dennis C. Shelly

1995-01-01

285

Data reduction problems using a 3-hole directional pressure probe to investigate mean flow characteristics in the vaneless gap between impeller and diffuser radial pump  

NASA Astrophysics Data System (ADS)

Among several different measurement techniques that have been already performed and presented in a radial impeller pump model including PIV, a directional pressure probe has been used to obtain mean velocity field and stagnation pressure between impeller outlet and the inlet vaned diffuser sections. These measurements are supposed to get more information not only about global pump head coefficient including vaned diffuser ones but also about impeller performances itself. Pressure probe information is affected by rotor-stator interactions and impeller rotation, and this paper presents a way to explain and correct pressure probe indications in order to achieve a better evaluation of overall impeller mean performances. The use of unsteady RANS calculation results is found to be a useful way to perform better data reduction analysis for this purpose.

Cherdieu, P.; Dupont, P.; Bayeul-Lainé, A. C.; Dazin, A.; Bois, G.

2013-12-01

286

Triple acting radial seal  

SciTech Connect

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

287

A fast and simple assay for busulfan in serum or plasma by liquid chromatography-tandem mass spectrometry using turbulent flow online extraction technology.  

PubMed

Busulfan is used in myeloablative preparation regimens for hematopoietic bone marrow transplantation. Due to its narrow therapeutic range therapeutic drug monitoring of busulfan is recommended. In this study a fast and simple method for measuring busulfan in serum or plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed utilizing turbulent flow online extraction technology. Serum or plasma was mixed with acetonitrile containing d(8)-busulfan. After centrifugation the supernatant was injected onto a turbulent flow preparatory column then transferred to a C18 analytical column monitored by a tandem mass spectrometer set at positive electrospray ionization. The analytical cycle time was 4.0min. The method was linear from 0.15 to 41.90?mol/L with an accuracy of 87.9-103.0%. Inter- and intra-assay CVs across four concentration levels were 2.1-7.8%. No significant carryover or ion suppression was observed. No interference was observed from commercial control materials containing more than 100 compounds. Comparison with a well established LC-MS/MS method using patient specimens (n=45) showed a mean bias 1.3% with Deming regression of slope 1.02, intercept -0.02?mol/L, and a linear correlation coefficient 0.9883. The LC-MS/MS method coupled with turbulent flow online sample cleaning technology described here offers reliable busulfan quantitation in serum or plasma with minimum manual sample preparation and was fully validated for clinical use. PMID:21030324

Bunch, Dustin R; Heideloff, Courtney; Ritchie, James C; Wang, Sihe

2010-12-01

288

Determination of perfluorinated chemicals in food and drinking water using high-flow solid-phase extraction and ultra-high performance liquid chromatography/tandem mass spectrometry.  

PubMed

For this study, we developed methods of determining ten perfluorinated chemicals in drinking water, milk, fish, beef, and pig liver using high-flow automated solid-phase extraction (SPE) and ultra-high performance liquid chromatography/tandem mass spectrometry. The analytes were separated on a core-shell Kinetex C18 column. The mobile phase was composed of methanol and 10-mM N-methylmorpholine. Milk was digested with 0.5 N potassium hydroxide in Milli-Q water, and was extracted with an Atlantic HLB disk to perform automated SPE at a flow rate ranged from 70 to 86 mL/min. Drinking water was directly extracted by the SPE. Solid food samples were digested in alkaline methanol and their supernatants were diluted and also processed by SPE. The disks were washed with 40% methanol/60% water and then eluted with 0.1% ammonium hydroxide in methanol. Suppression of signal intensity of most analytes by matrixes was lower than 50%; it was generally lower in fish and drinking water but higher in liver. Most quantitative biases and relative standard deviations were lower than 15%. The limits of detection for most analytes were sub-nanograms per liter for drinking water and sub-nanograms per gram for solid food samples. This method greatly shortened the time and labor needed for digestion, SPE, and liquid chromatography. This method has been applied to analyze 14 types of food samples. Perfluorooctanoic acid was found to be the highest among the analytes (median at 3.2-64 ng/g wet weight), followed by perfluorodecanoic acid (0.7-25 ng/g) and perfluorododecanoic acid (0.6-15 ng/g). PMID:22071607

Chang, Ying-Chia; Chen, Wen-Ling; Bai, Fang-Yu; Chen, Pau-Chung; Wang, Gen-Shuh; Chen, Chia-Yang

2012-01-01

289

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

290

Radial Turbine Cooling.  

National Technical Information Service (NTIS)

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 lim...

R. J. Roelke

1992-01-01

291

Radial nerve dysfunction (image)  

MedlinePLUS

The radial nerve travels down the arm and supplies movement to the triceps muscle at the back of the upper arm. ... the wrist and hand. The usual causes of nerve dysfunction are direct trauma, prolonged pressure on the ...

292

Radial nerve dysfunction  

MedlinePLUS

... following symptoms may occur: Abnormal sensations Hand or forearm ("back" of the hand) "Thumb side" (radial surface) ... wrist or fingers Muscle loss ( atrophy ) in the forearm Weakness of the wrist and finger Wrist or ...

293

Radial Artery Catheterization  

MedlinePLUS

... Institution: NIH Library User Name Password Sign In Cardiology Patient Page Radial Artery Catheterization Nicholas R. Balaji , ... Correspondence to Pinak B. Shah, MD, Director, Interventional Cardiology Training Program, Brigham and Women's Hospital, 75 Francis ...

294

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

295

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

PubMed

The objective of this work was to develop a reliable, rugged high-performance liquid chromatographic (HPLC) method for determination of trace levels of bromate (< 10 micrograms/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 post-column reaction based on oxidation of o-dianisidine in acidic solution to a product detected at 500 nm provided selective measurement of the oxidants. The limit of detection and the limit of quantitation were 1 and 3 micrograms/l, respectively. Iodate, chlorite, and nitrite were chromatographically separated from bromate and measured by monitoring the post-column reaction. Chloride and chlorate at levels that might be found in bottled water did not interfere with the determination of bromate. Bromate was detected in bottled waters at concentrations up to 40 micrograms/l. PMID:8871120

Warner, C R; Daniels, D H; Joe, F L; Diachenko, G W

1996-01-01

296

Hydrodynamic constraints on the radial structure of late-type galaxy disks  

Microsoft Academic Search

Hydrodynamic constraints or driving forces that determine steady disk gas radial distributions are discussed, and observed gas distributions in late-type disks and correlations with disk rotation curves are analyzed. Evidence for quasi-steady states with radial gas flow is examined, and gas consumption rates and stellar density profiles are discussed, as are models of steady states with radial flows and more

Curtis Struck-Marcell

1991-01-01

297

Understanding the mechanism of virus removal by Q sepharose fast flow chromatography during the purification of CHO-cell derived biotherapeutics.  

PubMed

During production of therapeutic monoclonal antibodies (mAbs) in mammalian cell culture, it is important to ensure that viral impurities and potential viral contaminants will be removed during downstream purification. Anion exchange chromatography provides a high degree of virus removal from mAb feedstocks, but the mechanism by which this is achieved has not been characterized. In this work, we have investigated the binding of three viruses to Q sepharose fast flow (QSFF) resin to determine the degree to which electrostatic interactions are responsible for viral clearance by this process. We first used a chromatofocusing technique to determine the isoelectric points of the viruses and established that they are negatively charged under standard QSFF conditions. We then determined that virus removal by this chromatography resin is strongly disrupted by the presence of high salt concentrations or by the absence of the positively charged Q ligand, indicating that binding of the virus to the resin is primarily due to electrostatic forces, and that any non-electrostatic interactions which may be present are not sufficient to provide virus removal. Finally, we determined the binding profile of a virus in a QSFF column after a viral clearance process. These data indicate that virus particles generally behave similarly to proteins, but they also illustrate the high degree of performance necessary to achieve several logs of virus reduction. Overall, this mechanistic understanding of an important viral clearance process provides the foundation for the development of science-based process validation strategies to ensure viral safety of biotechnology products. PMID:19575414

Strauss, Daniel M; Lute, Scott; Tebaykina, Zinaida; Frey, Douglas D; Ho, Cintia; Blank, Gregory S; Brorson, Kurt; Chen, Qi; Yang, Bin

2009-10-01

298

Liquid chromatography combined with thermospray and continuous-flow fast atom bombardment mass spectrometry of glycosides in crude plant extracts  

Microsoft Academic Search

In crude plant extracts, constituents of biological or pharmaceutical interest often exist in the form of glycosides. Off-line mass spectral investigations of these metabolites require soft ionisation techniques such as desorption chemical ionisation (DCI) or fast atom bombardment (FAB) if information on molecular mass or sugar sequence is desired. In LC-MS, glycosides can be ionised by using thermospray (TSP), continuous-flow

J.-L. Wolfender; K. Hostettmann; F. Abe; T. Nagao; H. Okabe; T. Yamauchi

1995-01-01

299

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

300

Measurement of radionuclides using ion chromatography and flow-call scintillation counting with pulse shape discrimination: Topical report, September 15, 1996--October 3, 1996, Tasks 1.11, 1.12 and 1.13  

SciTech Connect

Several flow-cell radiation detector systems are commercially available for quantification of aqueous radioactive solutions. These systems do not use the technique of pulse shape discrimination to identify the incident radiation and therefore are limited in environmental characterization application when coupled to an ion chromatography system. The advantages of the pulse shape discriminating flow-cell detector over the commercially available systems include: (1) lower minimum detectable activity for alpha radiation, (2) reduced radiological interferences that may exist between co-eluted alpha- and beta-emitting radionuclides, and (3) possible isotopic information from the ion chromatography system. For Tasks 1.1.1 and 1.1.2 of this project, several scintillation materials were investigated for pulse shape (alpha and beta) discrimination capabilities and the best candidate material was optimized. In addition, the following detector properties were also optimized: scintillator particle size, flow-cell tubing type, and electromagnetic as well as optical crosstalk between the photomultiplier tubes.

NONE

1997-04-01

301

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

302

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.

2011-05-26

303

AN OPTIMIZATION TECHNIQUE FOR RADIAL COMPRESSOR IMPELLERS  

Microsoft Academic Search

A software tool has been created to aid in automate d impeller design within an integrated design system for radial flow impellers. The design tool takes the results f rom the 1D preliminary design process and uses these to define a parameterized blade geometry, which incorporates features that are required for low mechanical stresses and s imple manufacturing. This geometry

Michael Casey; Frank Gersbach; Chris Robinson

2008-01-01

304

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

National Technical Information Service (NTIS)

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....

A. Mulder S. Skelley

2011-01-01

305

Zonal rate model for stacked membrane chromatography part II: characterizing ion-exchange membrane chromatography under protein retention conditions.  

PubMed

The Zonal Rate Model (ZRM) has previously been shown to accurately account for contributions to elution band broadening, including external flow nonidealities and radial concentration gradients, in ion-exchange membrane (IEXM) chromatography systems operated under nonbinding conditions. Here, we extend the ZRM to analyze and model the behavior of retained proteins by introducing terms for intra-column mass transfer resistances and intrinsic binding kinetics. Breakthrough curve (BTC) data 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). Through its careful accounting of transport nonidealities within and external to the membrane stack, the ZRM is shown to provide a useful framework for characterizing putative protein binding mechanisms and models, for predicting BTCs and complex elution behavior, including the common observation that the dynamic binding capacity can increase with linear velocity in IEXM systems, and for simulating and scaling separations using IEXM chromatography. Global fitting of model parameters is used to evaluate the performance of the Langmuir, bi-Langmuir, steric mass action (SMA), and spreading-type protein binding models in either correlating or fundamentally describing BTC data. When combined with the ZRM, the bi-Langmuir, and SMA models match the chromatography data, but require physically unrealistic regressed model parameters to do so. In contrast, for this system a spreading-type model is shown to accurately predict column performance while also providing a realistic fundamental explanation for observed trends, including an observed increase in dynamic binding capacity with flow rate. PMID:22012741

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

2012-03-01

306

Study of the abnormal late co-elution phenomenon of low density polyethylene in size exclusion chromatography using high temperature size exclusion chromatography and high temperature asymmetrical flow field-flow fractionation.  

PubMed

The elution behaviour of linear and branched polyethylene samples in SEC was studied. For the branched samples an abnormal late co-elution of large and small macromolecules manifests itself as an abnormal re-increase of the molar mass and the radius of gyration values detected with multi angle light scattering at high elution volumes in SEC. The late co-elution of small and large macromolecules cannot be explained by the SEC mechanism alone. The influence of several experimental parameters on the late co-elution was studied. It was found that the type of SEC column and the flow rate have a significant influence. The late eluting part of the sample was fractionated and separated by HT-SEC- and HT-AF4-MALS. The different results of both methods have been discussed with the aim to find possible explanations for the late elution. The experiments indicate that especially large branched structures show an increased tendency for the phenomenon. PMID:21276971

Otte, T; Klein, T; Brüll, R; Macko, T; Pasch, H

2011-07-01

307

Radial wedge flange clamp  

DOEpatents

A radial wedge flange clamp comprising a pair of flanges each comprising a plurality of peripheral flat wedge facets having flat wedge surfaces and opposed and mating flat surfaces attached to or otherwise engaged with two elements to be joined and including a series of generally U-shaped wedge clamps each having flat wedge interior surfaces and engaging one pair of said peripheral flat wedge facets. Each of said generally U-shaped wedge clamps has in its opposing extremities apertures for the tangential insertion of bolts to apply uniform radial force to said wedge clamps when assembled about said wedge segments.

Smith, Karl H. (Yorktown, VA)

2002-01-01

308

Speciation of metal-EDTA complexes by flow injection analysis with electrospray ionization mass spectrometry and ion chromatography with inductively coupled plasma mass spectrometry.  

PubMed

Flow injection analysis (FIA) with ESI-MS and ion chromatography (IC) with inductively coupled plasma-MS (ICP-MS) as the complementary technique have been explored for the determination of metal ions as their metal-EDTA complexes. ESI-MS enabled the identification of metal-EDTA complexes such as [Mn(EDTA)](2-), [Co(EDTA)](2-), [Ni(EDTA)](2-), [Cu(EDTA)](2-), [Zn(EDTA)](2-), [Pb(EDTA)](2-), and [Fe(EDTA)](1-) and their MS spectral showed that these metal-EDTA complexes were present in solution. Based on the ESI-MS, ion chromatographic separation and ICP-MS detection of these complexes are possible because IC-ICP-MS requires stable metal-EDTA complex during the chromatographic separation. The separation of these metal-EDTA complexes was achieved on an anion-exchange column with a mobile phase containing 30 mM NH(4)(HPO(4))(2) at pH 7.5 within 7 min with ICP-MS providing element specific detection. The ICP-MS LODs for the metal-EDTA were in the range of 0.1-0.5 microg/L with the exception of Fe (15 microg/L). The proposed method was a simple procedure for sample processing, using direct injection of sample without removal of sample matrix and was successfully applied to the determination of metal-EDTA complexes in real samples. PMID:18925619

Chen, ZuLiang; Sun, Qian; Xi, YunFei; Owens, Gary

2008-12-01

309

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

310

Development of a flow-through enzyme immunoassay and application in screening green coffee samples for ochratoxin A with confirmation by high-performance liquid chromatography.  

PubMed

A flow-through enzyme immunoassay has been developed for the screening of green coffee bean samples for ochratoxin A (OA) and was later used in a survey on OA in green coffee from different countries. The test has a sensitivity of 8 ng/g, and calculated recoveries ranged from 70 to 89% and from 86 to 95% for spiked and naturally contaminated samples, respectively. There were no significant differences in within-day and between-day assay performance (P > 0.05). Green coffee samples (15 Arabica and 7 Robusta) received from an international coffee trader were analyzed for intrinsic fungal contamination, screened for OA, and subsequently confirmed by high-performance liquid chromatography (HPLC). All 22 samples were contaminated by fungal species of the genus Aspergillus, while Penicillium species were isolated from a mere 13.6% of the total number of samples. Isolates were tested for their ability to produce OA, and only 3.9% were positive. There was no correlation between occurrence of OA-producing isolates and levels of OA in contaminated samples. Results of the screening procedure showed that 4 of the 22 samples were contaminated with 8 ng/g or higher. The HPLC method confirmed that the OA levels ranged from 27 to 168 ng/g. A fifth sample, which was shown to be negative during screening, had an OA concentration of 4 ng/g. There were no false negatives or positives recorded, and the flow-through enzyme immunoassay results correlated with those obtained by HPLC. PMID:11601711

Sibanda, L; De Saeger, S; Bauters, T G; Nelis, H J; Van Peteghem, C

2001-10-01

311

Radial transfer effects for poloidal rotation  

NASA Astrophysics Data System (ADS)

Radial transfer of energy or momentum is the principal agent responsible for radial structures of Geodesic Acoustic Modes (GAMs) or stationary Zonal Flows (ZF) generated by the turbulence. For the GAM, following a physical approach, it is possible to find useful expressions for the individual components of the Poynting flux or radial group velocity allowing predictions where a mathematical full analysis is unfeasible. Striking differences between up-down symmetric flux surfaces and asymmetric ones have been found. For divertor geometries, e.g., the direction of the propagation depends on the sign of the ion grad-B drift with respect to the X-point, reminiscent of a sensitive determinant of the H-mode threshold. In nonlocal turbulence computations it becomes obvious that the linear energy transfer terms can be completely overwhelmed by the action of the turbulence. In contrast, stationary ZFs are governed by the turbulent radial transfer of momentum. For sufficiently large systems, the Reynolds stress becomes a deterministic functional of the flows, which can be empirically determined from the stress response in computational turbulence studies. The functional allows predictions even on flow/turbulence states not readily obtainable from small amplitude noise, such as certain transport bifurcations or meta-stable states.

Hallatschek, Klaus

2010-11-01

312

Developments in Open Tubular Liquid Chromatography.  

National Technical Information Service (NTIS)

In this report the band broadening introduced by detection flow cell use in open tubular liquid chromatography (OTLC) was thoroughly examined. Serious loss of chromatographic efficiency and resolution can occur if the flow cell size is not properly matche...

J. D. Vargo M. P. Maskarinec M. J. Sepaniak

1984-01-01

313

[Radial nerve compression].  

PubMed

A new compression syndrome of the deep branch of the radial nerve is described, in which a sudden anterior displacement of a part of this nerve under maximal tension is followed by an axonotmesis. This happens in an area in which the deep branch of the radial nerve crossed some narrow structures which are unyielding and have more compression strength (tense cords of connective tissue Fig. 3). The operative finding of a torsion of the injured fascicles justifies the correctness of the immediate operative revision; otherwise the nerve regeneration would be impaired by the torted empty endoneural tubes. This description is a further constribution not observed before to the compression syndromes of the radial nerve, since in 1970 the author was able to give an explanation for the pathogenesis of compression palsies of the radial nerve, unclear up to that time but observed after forceful muscle contractions again and again since the beginning of this century. This observation gives the evidence that the occurrence of a peripheral compression lesion of nerves is not bound absolutely on the existence of a "physiological narrowness" (fibrous or osteofibrous tunnel etc.). This is also true for the median nerve. PMID:992486

Wilhelm, A

1976-01-01

314

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.

2011-05-25

315

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.

2011-05-03

316

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.

2011-05-19

317

Liquid chromatography combined with thermospray and continuous-flow fast atom bombardment mass spectrometry of glycosides in crude plant extracts.  

PubMed

In crude plant extracts, constituents of biological or pharmaceutical interest often exist in the form of glycosides. Off-line mass spectral investigations of these metabolites require soft ionisation techniques such as desorption chemical ionisation (DCI) or fast atom bombardment (FAB) if information on molecular mass or sugar sequence is desired. In LC-MS, glycosides can be ionised by using thermospray (TSP), continuous-flow fast atom bombardment (CF-FAB) or other interfaces. These techniques are thus potentially applicable to the on-line analysis of glycosides and can be applied to plant extract analysis. Thermospray (TSP) used with ammonium acetate as buffer provides mass spectra similar to those obtained with DCI-MS using NH3 and is potentially applicable to the on-line analysis of relatively small glycosides bearing no more than three sugar units. CF-FAB provides cleaner MS spectra than static FAB due to the lower concentration of the matrix used and can be applied to more polar compounds such as glycosides with a larger number of sugars. The use of a special setup involving post-column addition of the buffer or the matrix and splitting allows LC-UV, TSP LC-MS and CF-FAB LC-MS to be performed with the same standard HPLC conditions. Different crude plant extracts containing various types of glycosides with one to eight sugar units have been analysed by both TSP and CF-FAB. Cardenolides from Nerium odorum (Apocynaceae) and saponins from Swarzia madagascariensis (Leguminosae), Aster scaber and Aster tataricus (Asteraceae) have been studied by LC-MS. The combination of these two interfaces for the HPLC screening of crude plant extracts is discussed. PMID:8556148

Wolfender, J L; Hostettmann, K; Abe, F; Nagao, T; Okabe, H; Yamauchi, T

1995-09-29

318

Radial Halbach Magnetic Bearings  

NASA Technical Reports Server (NTRS)

Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while minimizing it on the opposite side. The advantage of this configuration is that it makes it possible to approach the theoretical maximum force per unit area that could be exerted by a given amount of permanent-magnet material. The configuration is named after physicist Klaus Halbach, who conceived it for use in particle accelerators. Halbach arrays have also been studied for use in magnetic-levitation ("maglev") railroad trains. In a radial Halbach magnetic bearing, the basic Halbach arrangement is modified into a symmetrical arrangement of sector-shaped permanent magnets mounted on the outer cylindrical surface of a drum rotor (see Figure 2). The magnets are oriented to concentrate the magnetic field on their radially outermost surface. The stator coils are mounted in a stator shell surrounding the rotor.

Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

2009-01-01

319

High-Performance Liquid Chromatography  

NASA Astrophysics Data System (ADS)

High-performance liquid chromatography (HPLC) developed during the 1960s as a direct offshoot of classic column liquid chromatography through improvements in the technology of columns and instrumental components (pumps, injection valves, and detectors). Originally, HPLC was the acronym for high-pressure liquid chromatography, reflecting the high operating pressures generated by early columns. By the late 1970s, however, high-performance liquid chromatography had become the preferred term, emphasizing the effective separations achieved. In fact, newer columns and packing materials offer high performance at moderate pressure (although still high pressure relative to gravity-flow liquid chromatography). HPLC can be applied to the analysis of any compound with solubility in a liquid that can be used as the mobile phase. Although most frequently employed as an analytical technique, HPLC also may be used in the preparative mode.

Reuhs, Bradley L.; Rounds, Mary Ann

320

Statistical theory of chromatography: new outlooks for affinity chromatography.  

PubMed Central

We have developed further the statistical approach to chromatography initiated by Giddings and Eyring, and applied it to affinity chromatography. By means of a convenient expression of moments the convergence towards the Laplace-Gauss distribution has been established. The Gaussian character is not preserved if other causes of dispersion are taken into account, but expressions of moments can be obtained in a generalized form. A simple procedure is deduced for expressing the fundamental constants of the model in terms of purely experimental quantities. Thus, affinity chromatography can be used to determine rate constants of association and dissociation in a range considered as the domain of the stopped-flow methods.

Denizot, F C; Delaage, M A

1975-01-01

321

Axonemal radial spokes  

PubMed Central

The radial spoke (RS) is a complex of at least 23 proteins that works as a mechanochemical transducer between the central?pair apparatus and the peripheral microtubule doublets in eukaryotic flagella and motile cilia. The RS contributes to the regulation of the activity of dynein motors, and thus to flagellar motility. Despite numerous biochemical, physiological and structural studies, the mechanism of the function of the radial spoke remains unclear. Detailed knowledge of the 3D structure of the RS protein complex is needed in order to understand how RS regulates dynein activity. Here we review the most important findings on the structure of the RS, including results of our recent cryo?electron tomographic analysis of the RS protein complex.

Pigino, Gaia; Ishikawa, Takashi

2012-01-01

322

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

323

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

1986-08-12

324

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

325

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

326

Highly selective and sensitive assay for paclitaxel accumulation by tumor cells based on selective solid phase extraction and micro-flow liquid chromatography coupled to mass spectrometry.  

PubMed

The taxanes are among the most important cancer chemotherapy drugs approved for clinical use in the last two decades. Paclitaxel is used as first-line therapy for a variety of cancers, and numerous drug delivery approaches are under investigation to enhance its selectivity and effectiveness against tumors. One strategy is to produce sustained, low drug levels within the tumor to enhance apoptosis and inhibit angiogenesis. The interest in altering drug concentration/time exposure profiles to improve therapeutic outcomes creates the necessity to quantify low concentrations of paclitaxel in cells or tissues. Here, a selective solid phase extraction (SPE) method, coupled with a capillary liquid chromatography-tandem mass spectrometry (microLC-MS/MS) method, was developed to quantify low, therapeutically relevant concentrations of paclitaxel that could not be analyzed using conventional LC-MS/MS. Under optimized SPE wash and elution conditions, paclitaxel was selectively extracted from biological samples, and most matrix components were removed. A 150 x 0.5 mm ID ODS capillary column was used for microLC separation and the flow rate was 12 microL min(-1). Sample extracts were focused at the front of the microLC column and then eluted with a gradient. The lower limits of detection and quantification were 5 and 20 pg mL(-1), respectively, permitting quantification of paclitaxel in small tissue samples or in cultured cells exposed to low drug concentrations. The quantitative linear range was 20-20 000 pg mL(-1). The ability to quantify these low concentrations of paclitaxel provides an important tool to study the concentration-dependent pharmacological effects of this important drug. PMID:19082078

Gaspar, Julio R; Qu, Jun; Straubinger, Ninfa L; Straubinger, Robert M

2008-12-01

327

Antiproton compression and radial measurements  

SciTech Connect

Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile, and its relation to that of the electron plasma. We also measure the outer radial profile by ejecting antiprotons to the trap wall using an octupole magnet.

Andresen, G. B.; Bowe, P. D.; Hangst, J. S. [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Jenkins, M. J.; Joergensen, L. V.; Madsen, N.; Werf, D. P. van der [Department of Physics, Swansea University, Swansea SA2 8PP (United Kingdom); Bray, C. C.; Chapman, S.; Fajans, J.; Povilus, A.; Wurtele, J. S. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300 (United States); Cesar, C. L.; Lambo, R.; Silveira, D. M. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-972 (Brazil); Fujiwara, M. C. [TRIUMF, 4004 Wesbrook Mall, Vancouver BC, V6T 2A3 (Canada)] (and others)

2008-08-08

328

Radial Distribution Functions of  

NASA Astrophysics Data System (ADS)

Although many of the physical properties of the two metallic glasses, Fe(,40)Ni(,40)P(,14)B(,6) and Fe(,30)Ni(,50)P(,14)B(,6) have been measured and published in the literature, the structural properties of these two materials have not yet been determined. The atomic structure of amorphous materials is characterized by the reduced radial distribution function and the radial distribution function (RDF). These functions are determined by measuring the scattering of x-rays, neutrons, or electrons from the materials. For this research, the x-ray scattering from Fe(,40)Ni(,40)P(,14)B(,6) and Fe(,30)Ni(,50)P(,4)B(,6) was measured for values of the scattering parameters, K, from 1 to 17. The measurements were made with a two-theta diffractometer using MoK(alpha) radiation. The data were corrected for absorption, polarization, and multiple scattering. Theoretical Compton scattering corrections were applied. The interference function which is the corrected scattering intensity as a function of K was Fourier transformed, to obtain the reduced radial distribution function. The location of the first peak of this function gives the nearest neighbor distance as r(,1) = 2.54 angstroms, for both metallic glasses. This value is in good agreement with published results on related amorphous materials. The locations of the second and third peaks, which are not well resolved, were determined to be r(,2) = 4.18 and r(,3) = 4.80 for both materials. For comparison to dense random packing of hard spheres (DRPHS) models, r(,2) and r(,3) are expressed in terms of sphere diameters by dividing by r(,1) giving r(,2)/r(,1) = 1.65 and r(,3)/r(,1) = 1.89. These values are in very good agreement with the DRPHS model of Sadoc, Dixmier, and Guinier. The measured densities of Fe(,40)Ni(,40)P(,14)B(,6) and Fe(,30)Ni(,50)P(,14)B(,6) were 7.56 gm/cm('3) and 7.62 gm/cm('3), respectively. These densities and the reduced radial distribution functions were used to calculate the radial distribution functions. The coordination number, CN, which gives the average number of nearest neighbor atoms was calculated for each RDF. The values of CN for Fe(,40)Ni(,40)P(,14)B(,6) and Fe(,30)Ni(,50)P(,14)B(,6) were 11.7 and 11.4, respectively.

Malamas, John

329

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.

330

An inverse design method for radial turbomachines  

NASA Astrophysics Data System (ADS)

The calculation of compressible flow by computing the velocities and density throughout the three dimensional flow field is described. A second, approximate approach to solve the compressible flow problem is presented. In this approach the variation of density in the pitchwise direction is neglected and an approximate form of the continuity equation is used. In order to evaluate the method experimentally and assess the practical feasibility of the application of three dimensional blade geometries, a high speed small diameter radial inflow turbine was designed. The performance of this turbine is compared with that of three baseline impellers. The method is validated numerically by computing the flow through the designed impeller using inviscid and viscous flow analysis methods.

Zangeneh, M.

331

Computer Simulation of Radial Immunodiffusion  

PubMed Central

Theories of diffusion with chemical reaction are reviewed as to their contributions toward developing an algorithm needed for computer simulation of immunodiffusion. The Spiers-Augustin moving sink and the Engelberg stationary sink theories show how the antibody-antigen reaction can be incorporated into boundary conditions of the free diffusion differential equations. For this, a stoichiometric precipitate was assumed and the location of precipitin lines could be predicted. The Hill simultaneous linear adsorption theory provides a mathematical device for including another special type of antibody-antigen reaction in antigen excess regions of the gel. It permits an explanation for the lowered antigen diffusion coefficient, observed in the Oudin arrangement of single linear diffusion, but does not enable prediction of the location of precipitin lines. The most promising mathematical approach for a general solution is implied in the Augustin alternating cycle theory. This assumes the immunodiffusion process can be evaluated by alternating computation cycles: free diffusion without chemical reaction and chemical reaction without diffusion. The algorithm for the free diffusion update cycle, extended to both linear and radial geometries, is given in detail since it was based on gross flow rather than more conventional expressions in terms of net flow. Limitations on the numerical integration process using this algorithm are illustrated for free diffusion from a cylindrical well.

Trautman, Rodes

1972-01-01

332

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.

333

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

334

Radial tunnel syndrome.  

PubMed

Radial tunnel syndrome is a pain syndrome resulting from compression of the posterior interosseous nerve at the proximal forearm. It has no specific radiologic or electrodiagnostic findings. Treatment should be started conservatively; if not successful, surgical treatment is indicated. The posterior interosseous nerve may be explored through dorsal or anterior approaches. All the potential sites of entrapment should be released, including complete release of the superficial head of the supinator muscle. Surgical treatment is generally successful, but patients who have associated lateral epicondylitis or those who are involved in workers' compensation claims have less successful outcomes. PMID:23026469

Naam, Nash H; Nemani, Sajjan

2012-10-01

335

Harvesting the radial artery  

PubMed Central

The radial artery (RA) has emerged as an important arterial graft for coronary bypass surgery. With improving five-year patency rates and increasing uptake, great attention has been focused on the optimal conduit harvesting technique. We herein present our approach to RA harvesting. Prerequisites of a successful harvest include adherence to important anatomical landmarks, protection of the sensory innervation to the volar forearm, and meticulous handling of the RA branches. Regardless of the harvesting methodology chosen, adherence to a “no-touch” technique will optimize the patency and durability of the RA conduit.

Osterday, Robert M.; Brodman, Richard F.

2013-01-01

336

Radial reflection diffraction tomography  

DOEpatents

A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

Lehman, Sean K.

2012-12-18

337

Radial Reflection diffraction tomorgraphy  

DOEpatents

A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

Lehman, Sean K

2013-11-19

338

Radial cutting torch  

SciTech Connect

The project`s aim is to complete development of the Radial Cutting Torch, a pyrotechnic cutter, for use in all downhole tubular cutting operations in the petroleum industry. Project objectives are to redesign and pressure test nozzle seals to increase product quality, reliability, and manufacturability; improve the mechanical anchor to increase its temperature tolerance and its ability to function in a wider variety of wellbore fluids; and redesign and pressure test the RCT nozzle for operation at pressures from 10 to 20 ksi. The proposal work statement is included in the statement of work for the grant via this reference.

Robertson, M.C.

1997-01-08

339

Radial reflection diffraction tomography  

NASA Astrophysics Data System (ADS)

A wave-based tomographic imaging algorithm based upon a single rotating radially outward oriented transducer is developed. At successive angular locations at a fixed radius, the transducer launches a primary field and collects the backscattered field in a ``pitch/catch'' operation. The hardware configuration, operating mode, and data collection method are identical to that of most medical intravascular ultrasound (IVUS) systems. IVUS systems form images of the medium surrounding the probe based upon ultrasonic B scans, using a straight-ray model of sound propagation. The goal of this research is to develop a wave-based imaging algorithm using diffraction tomography techniques. Given the hardware configuration and the imaging method, this system is referred to as ``radial reflection diffraction tomography.'' Two hardware configurations are considered: a multimonostatic mode using a single transducer as described above, and a multistatic mode consisting of a single transmitter and an aperture formed by multiple receivers. In this latter case, the entire source/receiver aperture rotates about the fixed radius. Practically, such a probe is mounted at the end of a catheter or snaking tube that can be inserted into a part or medium with the goal of forming images of the plane perpendicular to the axis of rotation. An analytic expression for the multimonostatic inverse is derived, but ultimately the new Hilbert space inverse wave (HSIW) algorithm is used to construct images using both operating modes. Applications include improved IVUS imaging, bore hole tomography, and nondestructive evaluation (NDE) of parts with existing access holes. .

Lehman, Sean K.; Norton, Stephen J.

2004-10-01

340

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

341

Development of a quantitative LC-MS/MS analytical method coupled with turbulent flow chromatography for digoxin for the in vitro P-gp inhibition assay.  

PubMed

Caco-2 cells, the human colon carcinoma cells, are typically used for screening compounds for their permeability characteristics and P-glycoprotein (P-gp) interaction potential during discovery and development. The P-gp inhibition of test compounds is assessed by performing bi-directional permeability studies with digoxin, a well established P-gp substrate probe. Studies performed with digoxin alone as well as digoxin in presence of test compounds as putative inhibitors constitute the P-gp inhibition assay used to assess the potential liability of discovery compounds. Radiolabeled (3)H-digoxin is commonly used in such studies followed by liquid scintillation counting. This manuscript describes the development of a sensitive, accurate, and reproducible LC-MS/MS method for analysis of digoxin and its internal standard digitoxin using an on-line extraction turbulent flow chromatography coupled to tandem mass spectrometric detection that is amendable to high throughput with use of 96-well plates. The standard curve for digoxin was linear between 10 nM and 5000 nM with regression coefficient (R(2)) of 0.99. The applicability and reliability of the analysis method was evaluated by successful demonstration of efflux ratio (permeability B to A over permeability A to B) greater than 10 for digoxin in Caco-2 cells. Additional evaluations were performed on 13 marketed compounds by conducting inhibition studies in Caco-2 cells using classical P-gp inhibitors (ketoconazole, cyclosporin, verapamil, quinidine, saquinavir etc.) and comparing the results to historical data with (3)H-digoxin studies. Similarly, P-gp inhibition studies with LC-MS/MS analytical method for digoxin were also performed for 21 additional test compounds classified as negative, moderate, and potent P-gp inhibitors spanning multiple chemo types and results compared with the historical P-gp inhibition data from the (3)H-digoxin studies. A very good correlation coefficient (R(2)) of 0.89 between the results from the two analytical methods affords an attractive LC-MS/MS analytical option for labs that need to conduct the P-gp inhibition assay without using radiolabeled compounds. PMID:17524973

Smalley, James; Marino, Anthony M; Xin, Baomin; Olah, Timothy; Balimane, Praveen V

2007-07-01

342

Radial head fractures: indications and outcomes for radial head arthroplasty.  

PubMed

Radial head fractures without associated bony or ligamentous injury can be safely treated with internal fixation, if possible, or arthroplasty if nonreconstructable. However, nonreconstructable radial head fractures in association with elbow dislocation and/or ligamentous injury in the elbow or forearm represent a specific subset of injuries that requires restoration of the radiocapitellar articulation for optimal function. The purpose of this article was to summarize the indications for radial head arthroplasty and discuss the reported outcomes. PMID:23827844

Fowler, John R; Goitz, Robert J

2013-07-01

343

Harmonic source and type identification in a radial distribution system  

Microsoft Academic Search

To aid in locating the source and type of harmonics in a distribution system, a computer program called HARM TRACER has been developed. HARM TRACER is a reverse harmonic power flow study program which traces the flow of harmonics in a radial distribution system from the point of measurement to the harmonic source or sources. It does so by considering

Asrat Teshome

1991-01-01

344

Radial hydrodynamics in risers  

SciTech Connect

On the basis of the benchmark modeling exercise at Fluidization VIII, predicting riser hydrodynamics continues to be more of an art than a science. Ten different hydrodynamic models were compared with a set of experimental data that covered a wide range of operating conditions and showed reasonable to poor overall agreement. Herein, the authors describe the model that gave the best overall agreement with the experimental data. Density is calculated by a correlation based on slip factor, and the radial voidage profile depends solely on the cross-sectional average void fraction. Both the gas and velocity profile follows a power law type expression, the gas velocity at the wall is zero. The model predictions agree well with experiments conducted with sand but not as well as those conducted with fluidized catalytic cracking catalyst.

Godfroy, L.; Chaouki, J. [Ecole Polytechnique, Montreal, Quebec (Canada). Dept. of Chemical Engineering] [Ecole Polytechnique, Montreal, Quebec (Canada). Dept. of Chemical Engineering; Patience, G.S. [E.I. du Pont de Nemours and Co., Wilmington, DE (United States)] [E.I. du Pont de Nemours and Co., Wilmington, DE (United States)

1999-01-01

345

/Chromatography+RECOVERY=superresolution chromatography  

NASA Astrophysics Data System (ADS)

A method for improving the resolution of the chromatographic analysis based on deriving the point-spread function of a chromatographic column, i.e., a chromatogram of an individual compound, is described. The system of two data sets, namely, a chromatogram of a substance analyzed and a point-spread function of a chromatographic column in combination with the noise statistics, makes it possible to use the RECOVERY signal-reconstruction software package described in paper by Gelfgat et al. (Comp. Phys. Commun. 74 (1993) 335). The proposed method has been tested by chromatography of bovine serum albumin using gel filtration. The resultant resolution exceeds that reached using high-performance liquid chromatography (with the cost of the instruments being lower by a factor of 15-20).

Kosarev, E. L.; Muranov, K. O.

2003-04-01

346

Numerical simulation of radial compressor stages with seals and technological holes  

NASA Astrophysics Data System (ADS)

Article describes numerical simulations of an air flow in radial compressor stages in the NUMECA CFD software. Four different radial compressor stages were solved in this article. During the tasks evaluating the stepped and straight impeller seals and technological holes influence on working characteristics and the flow field was observed. Also the CFD results comparison with results from the empiric design tool is described.

Syka, Tomáš; Lu?á?ek, Ond?ej; K?ourek, Jind?ich

2014-03-01

347

DESIGN ANALYSIS OF RADIAL INFLOW TURBINES  

NASA Technical Reports Server (NTRS)

This program performs a velocity-diagram analysis required for determining geometry and estimating performance for radial-inflow turbines. Input design requirements are power, mass flow rate, inlet temperature and pressure, and rotative rate. The design variables include stator-exit angle, rotor-exit-tip to rotor-inlet radius ratio, rotor-exit-hub to tip radius ratio, and the magnitude and radial distribution of rotor-exit tangential velocity. The program output includes diameters, total and static efficiences, all absolute and relative temperatures, pressures, and velocities, and flow angles at stator inlet, stator exit, rotor inlet, and rotor exit. Losses accounted for in this program by the internal loss model are three-dimensional (profile plus end wall) viscous losses in the stator and the rotor, the disk-friction loss on the back side of the rotor, the loss due to the clearance between the rotor tip and the outer casing, and the exit velocity loss. The flow analysis is one-dimensional at the stator inlet, stator exit, and rotor inlet, each of these calculation stations being at a constant radius. At the rotor exit where there is a variation in flow-field radius, an axisymmetric two-dimensional analysis is made using constant height sectors. Simple radial equilibrium is used to establish the static pressure gradient at the rotor exit. This program is written in FORTRAN V and has been implemented on a UNIVAC 1100 series computer with a memory requirement of approximately 22K of 36 bit words.

Glassman, A. J.

1994-01-01

348

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.

349

Atomic Force Microscope Mediated Chromatography  

NASA Technical Reports Server (NTRS)

The atomic force microscope (AFM) is used to inject a sample, provide shear-driven liquid flow over a functionalized substrate, and detect separated components. This is demonstrated using lipophilic dyes and normal phase chromatography. A significant reduction in both size and separation time scales is achieved with a 25-micron-length column scale, and one-second separation times. The approach has general applications to trace chemical and microfluidic analysis. The AFM is now a common tool for ultra-microscopy and nanotechnology. It has also been demonstrated to provide a number of microfluidic functions necessary for miniaturized chromatography. These include injection of sub-femtoliter samples, fluidic switching, and sheardriven pumping. The AFM probe tip can be used to selectively remove surface layers for subsequent microchemical analysis using infrared and tip-enhanced Raman spectroscopy. With its ability to image individual atoms, the AFM is a remarkably sensitive detector that can be used to detect separated components. These diverse functional components of microfluidic manipulation have been combined in this work to demonstrate AFM mediated chromatography. AFM mediated chromatography uses channel-less, shear-driven pumping. This is demonstrated with a thin, aluminum oxide substrate and a non-polar solvent system to separate a mixture of lipophilic dyes. In conventional chromatographic terms, this is analogous to thin-layer chromatography using normal phase alumina substrate with sheardriven pumping provided by the AFM tip-cantilever mechanism. The AFM detection of separated components is accomplished by exploiting the variation in the localized friction of the separated components. The AFM tip-cantilever provides the mechanism for producing shear-induced flows and rapid pumping. Shear-driven chromatography (SDC) is a relatively new concept that overcomes the speed and miniaturization limitations of conventional liquid chromatography. SDC is based on a sliding plate system, consisting of two flat surfaces, one of which has a recessed channel. A fluid flow is produced by axially sliding one plate past another, where the fluid has mechanical shear forces imposed at each point along the channel length. The shear-induced flow rates are very reproducible, and do not have pressure or voltage gradient limitations. SDC opens up a new range of enhanced separation kinetics by permitting the sample confinement with submicron dimensions. Small, highly confined liquid is advantageous for chromatographic separation because the separation rate is known to scale according to the square of the confined sample diameter. In addition, because shear-driven flows are not limited by fluid velocity, shear-driven liquid chromatography may provide up to 100,000 plate efficiency.

Anderson, Mark S.

2013-01-01

350

Radially sandwiched cylindrical piezoelectric transducer  

NASA Astrophysics Data System (ADS)

A new type of radially sandwiched piezoelectric short cylindrical transducer is developed and its radial vibration is studied. The transducer is composed of a solid metal disk, a radially polarized piezoelectric ceramic short tube and a metal tube. The radial vibrations of the solid metal disk, the radially polarized piezoelectric tube and the metal tube are analyzed and their electromechanical equivalent circuits are introduced. Based on the mechanical boundary conditions among the metal disk, the piezoelectric tube and the metal tube, a three-port electromechanical equivalent circuit for the radially sandwiched transducer is obtained and the frequency equation is given. The theoretical relationship of the resonance and anti-resonance frequencies and the effective electromechanical coupling coefficient with the geometrical dimensions is analyzed. The radial vibration of the sandwiched transducer is simulated by using two different numerical methods. It is shown that the analytical resonance and anti-resonance frequencies are in good agreement with the numerically simulated results. The transducer is expected to be used in piezoelectric resonators, actuators and ultrasonic radiators in ultrasonic and underwater sound applications.

Lin, Shuyu; Fu, Zhiqiang; Zhang, Xiaoli; Wang, Yong; Hu, Jing

2013-01-01

351

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.

2011-05-26

352

Atomic force microscope mediated chromatography.  

PubMed

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. PMID:23464258

Anderson, M S

2013-02-01

353

Entropy generation of radial rotation convective channels  

NASA Astrophysics Data System (ADS)

The exchange of heat between two fluids is established by radial rotating pipe or a channel. The hotter fluid flows through the pipe, while the cold fluid is ambient air. Total length of pipe is made up of multiple sections of different shape and position in relation to the common axis of rotation. In such heat exchanger the hydraulic and thermal irreversibility of the hotter and colder fluid occur. Therefore, the total entropy generated within the radial rotating pipe consists of the total entropy of hotter and colder fluid, taking into account all the hydraulic and thermal irreversibility of both fluids. Finding a mathematical model of the total generated entropy is based on coupled mathematical expressions that combine hydraulic and thermal effects of both fluids with the complex geometry of the radial rotating pipe. Mathematical model follows the each section of the pipe and establishes the function between the sections, so the total generated entropy is different from section to section of the pipe. In one section of the pipe thermal irreversibility may dominate over the hydraulic irreversibility, while in another section of the pipe the situation may be reverse. In this paper, continuous analytic functions that connect sections of pipe in geometric meaning are associated with functions that describe the thermo-hydraulic effects of hotter and colder fluid. In this way, the total generated entropy of the radial rotating pipe is a continuous analytic function of any complex geometry of the rotating pipe. The above method of establishing a relationship between the continuous function of entropy with the complex geometry of the rotating pipe enables indirect monitoring of unnecessary hydraulic and thermal losses of both fluids. Therefore, continuous analytic functions of generated entropy enable analysis of hydraulic and thermal irreversibility of individual sections of pipe, as well as the possibility of improving the thermal-hydraulic performance of the rotating pipe consisting of n sections. Analytical modeling enabled establishing of a mathematical model of the total generated entropy in a radial rotating pipe, while the generated entropy of models with radial rotating pipe were determined by experimental testing, with comparisons of the achieved results.

Ali?, Fikret

2012-03-01

354

Ion Exchange Application of Overpressured Thin-Layer Chromatography  

Microsoft Academic Search

The application of overpressured thin-layer chromatography introduced into the field of ion exchange chromatography. The basic differences between overpressured thin-layer chromatography and classical thin-layer chromatography are discussed including the distinction between the separations performed on thin-layer plates containing silica gel and a mixture of ion exchanger material and silica gel. The basic increase of flow velocity of solvent front with

Huba Kalász; János Nagy

1981-01-01

355

Some observations of the effects of radial distortions on performance of a transonic rotating blade row  

NASA Technical Reports Server (NTRS)

A single rotating blade row was tested with two magnitudes of tip radial distortion and two magnitudes of hub radial distortion imposed on the inlet flow. The rotor was about 50 centimeters (20 in.) in diameter and had a design operating tip speed of approximately 420 meters per second (1380 ft/sec). Overall performance at 60, 80, and 100 percent of equivalent design speed generally showed a decrease (compared to undistorted flow) in rotor stall margin with tip radial distortion but no change, or a slight increase, in rotor stall margin with hub radial distortion. At design speed there was a decrease in rotor overall total pressure ratio and choke flow with all inlet flow distortions. Radial distributions of blade element parameters are presented for selected operating conditions at design speed.

Sandercock, D. M.; Sanger, N. L.

1974-01-01

356

Effect of parallel segmented flow chromatography on the height equivalent to a theoretical plate. I-performance of 4.6mm×30mm columns packed with 3.0?m Hypurity-C18 fully porous particles.  

PubMed

The mass transfer kinetics in short and wide 4.6mm×30mm columns packed with 3.0?m Hypurity-C18 fully porous particles were measured for three different configurations of the inlet sample distribution and outlet sample collection: (1) both the inlet and outlet column endfittings are standard, (2) the inlet endfitting is standard while the outlet endfitting allows parallel segmentation of the exiting flow between a central and a peripheral region across the column diameter, and (3) both the inlet and outlet endfittings allow a parallel segmentation of the flow entering and exiting the column, respectively. The total reduced heights equivalent to a theoretical plate (HETP) were carefully measured, using the first and second central moments of the elution band profiles, obtained by its accurate numerical integration. The longitudinal diffusion term was measured at the lowest experimental reduced velocity applied. The solid-liquid mass transfer resistance was estimated from measurements of the intra-particle diffusivity using the Torquato's model of effective diffusion in packed beds. The trans-channel and short-range interchannel eddy diffusion HETP terms were taken from data obtained by solving numerically the Navier-Stokes equations and simulating advective-diffusive transport in computer-generated random sphere packings. The results clearly show that the trans-column eddy diffusion HETP term can account for up to 85% of the total intrinsic HETP (corrected for extra-column contributions) of the standard columns. Parallel segmented flow chromatography can reduce this contribution by half at high velocities, by eliminating most of the baseline peak tailing. This holds true irrespective of the retention factor of the analyte. It was found also that segmenting the inlet/outlet flow increases detection sensitivity by 25-50% for peaks with large to small retention factors, respectively. In practice, the advantage of parallel segmented flow chromatography in gradient elution (thin peak widths) is essentially limited by post-column bandspreading and diffusion in the dwell volume of the instrument used. Analyst should minimize post-column bandspreading (caused by connectors and detection cell volume) and synchronize the eluent composition in the peripheral and central inlet ports of the column, by using two separate pumps with appropriate dwell volumes. PMID:23706347

Gritti, Fabrice; Guiochon, Georges

2013-07-01

357

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

358

A novel technique for the analysis of radial distribution systems  

Microsoft Academic Search

This paper presents a novel technique to obtain the solution of load flow in radially operated distribution networks, in which the loads can be represented by any model. This method is simple, easy to program and is based on the formation of a constant sparse upper triangular matrix, which is used to determine the bus voltages. Test results of IEEE

P. Aravindhababu; S. Ganapathy; K. R. Nayar

2001-01-01

359

Radial head dislocation during proximal radial shaft osteotomy.  

PubMed

The following case report describes a 48-year-old female patient with a longstanding both-bone forearm malunion, who underwent osteotomies of both the radius and ulna to improve symptoms of pain and lack of rotation at the wrist. The osteotomies were templated preoperatively. During surgery, after performing the planned radial shaft osteotomy, the authors recognized that the radial head was subluxated. The osteotomy was then revised from an opening wedge to a closing wedge with improvement of alignment and rotation. The case report discusses the details of the operation, as well as ways in which to avoid similar shortcomings in the future. PMID:24559636

Hazel, Antony; Bindra, Randy R

2014-03-01

360

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...

361

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

362

Acute closed radial nerve injury  

PubMed Central

We present a 45-year-old patient who had acute radial nerve palsy following a blunt trauma without any fracture or dislocation. He was injured by strucking in a combat three months ago. The patient has been followed by application of a long-arm plaster cast before referred to our clinic. Preoperative electromyoneurography and magnetic resonance imaging (MRI) indicated that there was a radial nerve injury on humeral groove. The British Medical Research Council (MRC) grade was 2/5 on his wrist preoperatively. The patient underwent an operation under general anesthesia. It was seen to be a second-degree nerve injury. The patient has subsequently regained full movement on his wrist and finger extension in six months. We suggest that a detailed clinical and electrodiagnostical evaluation is necessary in patients who have radial nerve injury when deciding the treatment, conservative or surgical.

Tuncel, Umut; Turan, Aydin; Kostakoglu, Naci

2011-01-01

363

Radial transport in the central cell of the tandem mirror experiment  

Microsoft Academic Search

An experimental study of radial transport in the Tandem Mirror Experiment is reported here. Plasma parameters were measured in a series of well-diagnosed plasma discharges. A negative electric current (80 +- 40 A within a 30-cm radius) flowed to the end wall, implying an equal radial loss of plasma ions. The axial losses of plasma ions were 100 A from

R. P. Drake; E. B. Hooper Jr.; C. V. Karmendy; S. L. Allen; T. A. Casper; J. F. Clauser; F. H. Coensgen; R. H. Cohen; D. L. Correll; J. C. Davis; J. H. Foote; A. H. Futch; R. K. Goodman; D. P. Grubb; G. E. Gryczkowski

1982-01-01

364

Initial experiments using radial foils on the Cornell Beam Research Accelerator pulsed power generator  

Microsoft Academic Search

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

P.-A. Gourdain; I. C. Blesener; J. B. Greenly; D. A. Hammer; P. F. Knapp; B. R. Kusse; P. C. Schrafel

2010-01-01

365

Initial experiments using radial foils on the Cornell Beam Research Accelerator pulsed power generator  

Microsoft Academic Search

A novel technique involving radial foil explosions can produce high energy density plasmas. A current flows radially inward in a 5 mum 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

P.-A. Gourdain; I. C. Blesener; J. B. Greenly; D. A. Hammer; P. F. Knapp; B. R. Kusse; P. C. Schrafel

2010-01-01

366

Sharp Dissection versus Electrocautery for Radial Artery Harvesting  

PubMed Central

Radial arteries have been increasingly used during the last decade as conduits for coronary artery revascularization. Although various harvesting techniques have been described, there has been little comparative study of arterial damage and patency. A radial artery graft was used in 44 consecutive patients, who were randomly divided into 2 groups. In the 1st group, the radial artery was harvested by sharp dissection and in the 2nd, by electrocautery. These groups were compared with regard to radial artery free flow, harvest time, number of clips used, complications, and endothelial damage. Radial artery free flow before and after intraluminal administration of papaverine was significantly greater in the electrocautery group (84.3 ± 50.7 mL/min and 109.7 ± 68.5 mL/min) than in the sharp-dissection group (52.9 ± 18.3 mL/min and 69.6 ± 28.2 mL/ min) (P =0.003). Harvesting time by electrocautery was significantly shorter (25.4 ± 4.3 min vs 34.4 ± 5.9 min) (P =0.0001). Electrocautery consumed an average of 9.76 clips, versus 22.45 clips consumed by sharp dissection. The 2 groups were not different regarding postoperative complications, except for 3 cases of temporary paresthesia of the thumb in the electrocautery group; histopathologic examination found no endothelial damage. We conclude that radial artery harvesting by electrocautery is faster and more economical than harvesting by sharp dissection and is associated with better intraoperative flow and good preservation of endothelial integrity.

Marzban, Mehrab; Arya, Reza; Mandegar, Mohammad Hossein; Karimi, Abbas Ali; Abbasi, Kiomars; Movahed, Namvar; Abbasi, Seyed Hesameddin

2006-01-01

367

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

368

Radial spreading of viscous-gravity currents with solidifying crust  

NASA Technical Reports Server (NTRS)

In the present investigation of solidifying-crust effects on the dynamics and surface morphology of radial viscous-gravity currents, polyethylene glycol inflows into the base of a tank holding a cold sucrose solution are used as analogs. As the radial current advanced away from the inlet, its surface solidified and deformed through a combination of folding anf fracturing. When cooling was sufficiently rapid, solid crust formed and caused the spreading rate to increase; progressively colder experiments revealed a sequence of surface morphologies resembling features of cooling lava flows and lava lakes, including multiarmed rift structures with shear offsets and bulbous lobate forms resembling pillow lavas on the ocean floor.

Fink, Jonathan H.; Griffiths, Ross W.

1990-01-01

369

An automated method for the simultaneous measurement of azole antifungal drugs in human plasma or serum using turbulent flow liquid chromatography-tandem mass spectrometry.  

PubMed

Azole antifungal drugs are important in the prophylaxis and treatment of invasive aspergillosis. Therapeutic drug monitoring may be indicated to (1) monitor adherence, (2) guide dosage and (3) minimise the risk of drug-drug interactions and dose-related toxicity. TurboFlow(TM) technology offers online, automated sample preparation. An Aria Transcend(TM) TLX-II coupled with a TSQ Vantage(TM) MS was used. Centrifuged samples (25 ?L) were mixed with internal standard solution (975 ?L) and 30 ?L injected directly onto a C18-P-XL TurboFlow column. Analytes were focussed onto a Phenomenex Gemini Phenyl analytical column and eluted using a methanol/water gradient (flow-rate, 0.8 mL/min). Analytes were monitored in selected reaction monitoring mode (two transitions per analyte, positive mode APCI). Calibration ranges were as follows: itraconazole, hydroxyitraconazole, and posaconazole 0.05-5.0 mg/L; voriconazole and fluconazole 0.1-10 mg/L. Total analysis time was 12 min. TurboFlow column recovery was >77% for all analytes. Calibration was linear (R (2)?>?0.99) for all analytes. Inter- and intra-assay imprecision (% RSD) was <8% and accuracy (nominal internal quality control values) 90-105% for all analytes. The limit of detection was 0.01 mg/L for all analytes. No matrix effects were observed. This method is simple, robust and suitable for measuring these compounds at concentrations attained during therapy. PMID:22695504

Couchman, L; Buckner, S L; Morgan, P E; Ceesay, M M; Pagliuca, A; Flanagan, R J

2012-08-01

370

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

Microsoft Academic Search

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

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

2006-01-01

371

Effects of stream-associated fluctuations upon the radial variation of average solar wind parameters  

NASA Technical Reports Server (NTRS)

A numerical MHD model in both spherically symmetric time-dependent and corotating equatorial flow approximations is used to compute the effects of nonlinear fluctuations due to solar wind streams upon radial gradients of average solar wind parameters. Significant effects of correlations between fluctuations on the gradients of azimuthal magnetic field, radial velocity, density, and azimuthal velocity are found. It is found that nonlinear fluctuations are a significant effect in determining the radial gradients of the solar wind at distances as small as 0.2 AU; at distances greater than 1 AU, nonlinear fluctuations dominate the behavior of the radial gradients.

Goldstein, B. E.; Jokipii, J. R.

1977-01-01

372

Radial Clearance of Antifriction Bearings.  

National Technical Information Service (NTIS)

The article concerns in detail the radial clearance of different antifriction bearings which belong to important parameters which influence the longevity of the bearing to a certain extent. The effect of the influence of assembly and the wear on the radia...

V. Patocka

1968-01-01

373

Radial modulation of single microbubbles.  

PubMed

Radial modulation imaging is a new promising technique to improve contrast-enhanced ultrasound images. The method is based on dual-frequency insonation of contrast agent microbubbles. A low-frequency (LF) pulse is used to modulate the responses of the microbubbles to a high-frequency (HF) imaging pulse. Inverting the LF pulse induces amplitude and phase differences in the HF response of contrast agent microbubbles, which can be detected using Doppler techniques. Although the technique has been successfully implemented, no consensus persists on parameter choice and resulting effects. In a separate study, "compression-only" behavior of coated microbubbles was observed. Compression-only behavior could be beneficial for radial modulation imaging. This was investigated using high-speed camera recordings and simulations. We recorded the vibrations of 78 single microbubbles in a dual-frequency ultrasound field. The results showed that the LF pulse induced significant compression-only behavior, which for microbubble sizes below and at HF resonance resulted in high radial amplitude modulation. It, however, also appeared that, for radial modulation imaging, microbubble size is more important than resonance and compression-only effects. PMID:19942524

Emmer, Marcia; Vos, Hendrik J; Versluis, Michel; de Jong, Nico

2009-11-01

374

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

375

Use of on-line stop-flow heart-cutting two-dimensional high performance liquid chromatography for simultaneous determination of 12 major constituents in tartary buckwheat (Fagopyrum tataricum Gaertn).  

PubMed

The use of two-dimensional liquid chromatography (2D-LC) for quantification studies presents challenges with respect to repeatability, precision, and robustness. The present study used an on-line stop-flow heart-cutting 2D-LC system to determine 12 chemical constituents in tartary buckwheat. A combination of various stationary phases was developed and bridged using two switch valves as the interface. Hydrophilic interaction chromatography was chosen for separation in the first dimension ((1)D), and mixed mode stationary phases (an amide polar-embedded phase and alkyl-phenyl phase) were used in parallel for separation in the second dimension ((2)D). The mobile phase comprised acetonitrile and water containing 0.03% aqueous phosphoric acid. The sample was separated into two fractions on the (1)D column (HILIC-10 column) using 5% acetonitrile. One fraction, mainly comprising flavonoids, was directly eluted onto the head of (2)D column (Polar Advantage II column) and further separated using a linear gradient of 11-23% acetonitrile. The second fraction, containing phenylpropanoid glycosides, was trapped on the (1)D column. This retained fraction was back-flushed onto the (2)D column (Phenyl-1 column) and separated using a linear gradient of 35-43% acetonitrile. An on-line stop-flow heart-cutting 2D-LC system was successfully developed with column switching and back-flush. This 2D-LC system was validated and was able to simultaneously determine 12 major components in tartary buckwheat: seven flavonoids, four phenylpropanoid glycosides, and N-trans-feruloyltyramine. The system showed good performance with respect to linearity (r>0.996), repeatability (RSD, relative standard deviation<3.4%), intra-day and inter-day precision (RSD<4.6%), recovery (91.2-108%), limit of detection (LOD) (0.05-0.21?g/mL), and limit of quantification (LOQ) (0.10-0.41?g/mL). The on-line stop-flow heart-cutting 2D-LC system offers a potential approach to analyze compounds, which have similar structures but different polarities, in herbal medicines. PMID:23870547

Ren, Qiang; Wu, Caisheng; Zhang, Jinlan

2013-08-23

376

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

Eichinger, John

2009-05-15

377

Basic Principles of Chromatography  

NASA Astrophysics Data System (ADS)

Chromatography has a great impact on all areas of analysis and, therefore, on the progress of science in general. Chromatography differs from other methods of separation in that a wide variety of materials, equipment, and techniques can be used. [Readers are referred to references (1-19) for general and specific information on chromatography.]. This chapter will focus on the principles of chromatography, mainly liquid chromatography (LC). Detailed principles and applications of gas chromatography (GC) will be discussed in Chap. 29. In view of its widespread use and applications, high-performance liquid chromatography (HPLC) will be discussed in a separate chapter (Chap. 28). The general principles of extraction are first described as a basis for understanding chromatography.

Ismail, Baraem; Nielsen, S. Suzanne

378

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

379

An automated method for the measurement of a range of tyrosine kinase inhibitors in human plasma or serum using turbulent flow liquid chromatography-tandem mass spectrometry.  

PubMed

Tyrosine kinase inhibitors (TKIs) are used to treat a number of cancers, including chronic myeloid leukaemia and hepatocellular carcinoma. Therapeutic drug monitoring (TDM) may be indicated to (1) monitor adherence, (2) guide dosage, and (3) minimise the risk of drug-drug interactions and dose-related toxicity. On-line, automated sample preparation provided by TurboFlow technology (ThermoFisher Scientific) in conjunction with the sensitivity and selectivity of tandem mass spectrometry (MS/MS) detection may be applied to the analysis of single drugs and metabolites. We report the use of TurboFlow LC-MS/MS for the analysis of nine TKIs and metabolites (imatinib, N-desmethylimatinib, dasatinib, nilotinib, erlotinib, gefitinib, lapatinib, sorafenib, sunitinib) in human plasma or serum for TDM purposes. An Aria Transcend TLX-II system coupled with a TSQ Vantage was used. Samples (50 ?L) were vortex mixed with internal standard solution (150 ?L imatinib-D(8), gefitinib-D(8), sunitinib-D(10), and nilotinib-(13)C (2) (15) N(2) in acetonitrile) and, after centrifugation 100 ?L supernatant were injected directly onto a 50 × 0.5-mm Cyclone TurboFlow column. Analytes were focussed onto a 50 × 2.1-mm (3 ?m) Hypersil GOLD analytical column and eluted with an acetonitrile/water gradient. Analytes were monitored in selected reaction monitoring mode (positive APCI). Total analysis time was 7 min without multiplexing. Calibration was linear (R(2) > 0.99) for all analytes. Inter- and intra-assay precision (in percent relative standard deviation, RSD) was <11 % and accuracy 89-117 % for all analytes. No matrix effects were observed. This method is suitable for high-throughput TDM in patients undergoing chronic therapy with TKIs and has been utilised in the analysis of clinical samples. PMID:22526649

Couchman, L; Birch, M; Ireland, R; Corrigan, A; Wickramasinghe, S; Josephs, D; Spicer, J; Flanagan, R J

2012-06-01

380

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

381

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. J Orthop Sports Phys Ther 2014;44(5):377. doi:10.2519/jospt.2014.0406. PMID:24787327

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

2014-05-01

382

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.

Rahbar, Elaheh

2011-01-01

383

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.

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

2014-01-01

384

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

385

Velocidades radiales en Collinder 121  

NASA Astrophysics Data System (ADS)

Se han llevado a cabo observaciones espectroscópicas de unas treinta estrellas que son posibles miembros del cúmulo abierto Collinder 121. Las mismas fueron realizadas con el telescopio de 2.15m del Complejo Astronómico El Leoncito (CASLEO). El análisis de las velocidades radiales derivadas del material obtenido, confirma la realidad de Collinder 121, al menos desde el punto de vista cinemático. La velocidad radial baricentral (LSR) del cúmulo es de +17 ± 3 km.s-1. Esta velocidad coincide, dentro de los errores, con la velocidad radial (LSR) de la nebulosa anillo S308, la cual es de ~20 ± 10 km.s-1. Como S308 se encuentra físicamente asociada a la estrella Wolf-Rayet HD~50896, es muy probable que esta última sea un miembro de Collinder 121. Desde un punto de vista cinemático, la supergigante roja HD~50877 (K3Iab) también pertenecería a Collinder 121. Basándonos en la pertenencia de HD~50896 a Collinder 121, y en la interacción encontrada entre el viento de esta estrella y el medio interestelar circundante a la misma, se estima para este cúmulo una distancia del orden de 1 kpc.

Arnal, M.; Morrell, N.

386

Radial Photonic Crystals for Microwave Operation.  

National Technical Information Service (NTIS)

We analyze the properties of electromagnetic metamaterials with anisotropic constitutive parameters. Particularly, we analyze the so-called Radial Photonic Crystals, which are radially periodic structures verifying the Bloch theorem. This type of crystals...

A. Diaz-Rubio D. Torrent F. Cervera J. Carbonell M. A. Kirleis

2012-01-01

387

Implementing radial motion to the booster simulation  

SciTech Connect

It's a puzzle that high intensity beams prefer a particular radial motion during transition in the Booster, and the result of removing such a radial motion is to increase the transition loss. In order to understand this observation, the radial motion should be taken into account in the longitudinal simulation.

Yang, Xi; /Fermilab

2007-04-01

388

Flow-through dispersed carbon nanofiber-based microsolid-phase extraction coupled to liquid chromatography for automatic determination of trace levels of priority environmental pollutants.  

PubMed

Handling of carbon nanoparticles as sorptive materials in a flow-through packed-bed mode has been to date hampered by undue pressure drop and deteriorated retention efficiency because of nanoparticle bundling and entanglement. To surmount this limitation, a dedicated stirred-flow sorptive microchamber integrated in a fully automated sequential injection (SI) assembly is herein proposed for expedient handling and reuse of carbon nanoparticles in microsolid-phase extraction (?SPE) procedures. The assembled setup features automatic uptake, preconcentration, and retrieval of target organic species using dispersed nanoparticles as a front-end to liquid chromatographic (LC) assays. Chlorotriazine residues (atrazine, simazine, and propazine) and dealkylated metabolites thereof (deisopropyltriazine (DIA) and deethylatrazine (DEA)) were selected as model compounds because of their electron-poor aromatic structure and potentially strong ?-? interactions with electron-rich sorptive materials. The effect of several parameters on the analytical performance including the type and amount of nanoparticles (carbon nanofibers (CNFs), multiwalled carbon nanotubes (MWCNTs) and oxidized carbon nanotubes (MWCNT-COOH), the sample volume (breakthrough volume), the nature and volume of eluent, and the interface between the sample processing module and LC was explored in detail. Using dispersed CNFs at-line coupled to LC, absolute recovery percentages for 10 mL sample percolation were >94% for the overall herbicides with enrichment factors of ca. 20, limits of detection (S/N = 3) of 0.004-0.03 ng mL(-1), limits of quantification (S/N = 10) of 0.01-0.09 ng mL(-1) and repeatability within the range 0.5-1.8%. The SI-CNF-LC hyphenated system was harnessed to the analysis of not merely untreated environmental waters at concentration levels below those endorsed by the current EU Water Framework Directives but to crude soil extracts for which CNF reuse with no loss of retention efficiency was proven feasible by resorting to appropriate automatic regeneration procedures and internal standardization. PMID:21553915

Boonjob, Warunya; Miró, Manuel; Segundo, Marcela A; Cerdà, Víctor

2011-07-01

389

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

390

Should the radial artery be used as a bypass graft following radial access coronary angiography.  

PubMed

The radial artery (RA) is often selected as the next conduit of choice following the internal thoracic artery for coronary artery bypass grafting operations (CABG). Radial access coronary angiography (RA-CA) has grown in popularity among cardiologists and has been advocated as the access route of choice for coronary angiography and intervention by many groups. However, sheath insertion and instrumentation may lead to structural and functional damage to the RA, which may preclude its use as a bypass conduit. The increasing use of RA-CA may therefore have an adverse effect on the ability to use the RA as a bypass conduit at subsequent CABG. To review this, a best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was: 'should the radial artery be used as a bypass conduit following radial access coronary angiography'? Altogether, 167 papers were found using the reported search; 11 papers were identified that provided the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these studies were tabulated. Acute RA occlusion occurs in 2.3-30.5% of patients undergoing RA-CA. While a significant number of occluded RA's show recanalization on early follow-up, markers of endothelial function such as intima-media thickening (IMT) and flow-mediated dilatation remain impaired. RA-CA causes structural injury to the RA with evidence of histological injury (including intimal hyperplasia, periarterial tissue/fat necrosis and adventitial inflammation) along with intimal tears and medial dissections evident along the entire length of the vessel. Only one paper directly assesses patency rates of RA's used as bypass grafts following RA-CA finding a significant adverse effect on graft patency (77% patency in RA-CA, compared with 98% in the control group). We recommend avoiding the RA as a bypass conduit if it has previously been used for RA-CA. In situations where conduit options are limited, if possible, the RA should be avoided for at least 3 months following RA-CA and it may be beneficial to assess the RA's patency and flow characteristics with Doppler ultrasound preoperatively. PMID:24254539

Lim, Lisa M; Galvin, Sean D; Javid, Mohamed; Matalanis, George

2014-02-01

391

Automated and sensitive determination of four anabolic androgenic steroids in urine by online turbulent flow solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry: A novel approach for clinical monitoring and doping control.  

PubMed

A novel method for automated and sensitive analysis of testosterone, androstenedione, methyltestosterone and methenolone in urine samples by online turbulent flow solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry was developed. The optimization and validation of the method were discussed in detail. The Turboflow C18-P SPE column showed the best extraction efficiency for all the analytes. Nanogram per liter (ng/L) level of AAS could be determined directly and the limits of quantification (LOQs) were 0.01ng/mL, which were much lower than normally concerned concentrations for these typical anabolic androgenic steroids (AAS) (0.1ng/mL). The linearity range was from the LOQ to 100ng/mL for each compound, with the coefficients of determination (r(2)) ranging from 0.9990 to 0.9999. The intraday and interday relative standard deviations (RSDs) ranged from 1.1% to 14.5% (n=5). The proposed method was successfully applied to the analysis of urine samples collected from 24 male athletes and 15 patients of prostate cancer. The proposed method provides an alternative practical way to rapidly determine AAS in urine samples, especially for clinical monitoring and doping control. PMID:24840468

Guo, Feng; Shao, Jing; Liu, Qian; Shi, Jian-Bo; Jiang, Gui-Bin

2014-07-01

392

A radial mode ultrasonic horn for the inactivation of Escherichia coli K12.  

PubMed

Tuned cylindrical radial mode ultrasonic horns offer advantages over ultrasonic probes in the design of flow-through devices for bacterial inactivation. This study presents a comparison of the effectiveness of a radial horn and probe in the inactivation of Escherichia coli K12. The radial horn is designed using finite element analysis and the predicted modal parameters are validated using experimental modal analysis. A validated finite element model of the probe is also presented. Visual studies of the cavitation fields produced by the radial horn and probe are carried out using luminol and also backlighting to demonstrate the advantages of radial horns in producing a more focused cavitation field with widely dispersed streamers. Microbiological studies show that, for the same power density, better inactivation of E. coli K12 is achieved using the radial horn and, also, the radial horn offers greater achievable power density resulting in further improvements in bacterial inactivation. The radial horn is shown to be more effective than the probe device and offers opportunities to design in-line flow-through devices for processing applications. PMID:17368071

Hunter, G; Lucas, M; Watson, I; Parton, R

2008-02-01

393

Fabrication and test of radial grooved micro heat pipes  

Microsoft Academic Search

This paper describes the development of radial grooved micro heat pipes (MHPs) with a three-layer structure. The MHPs were designed to allow separation of the liquid and vapor flow to reduce the viscous shear force. The 5×5 cm2 MHP array was fabricated by using bulk micromachining and eutectic bonding techniques on 4-in. (100) silicon wafers. Experiments were undertaken to evaluate

Shung-Wen Kang; Sheng-Hong Tsai; Hong-Chih Chen

2002-01-01

394

Implementation of real-time two-dimensional nuclear magnetic resonance spectroscopy for on-flow high-performance liquid chromatography.  

PubMed

Directly coupled HPLC-NMR has become a powerful tool for separation and structural elucidation of unknown compounds. However, there are only a few reports on application of on-flow two-dimensional (2D) NMR in HPLC-NMR. Here we present an alternative method for recording real-time 2D-NMR spectrum (total correlation spectroscopy, TOCSY) on a commercial HPLC-NMR system. The method is based on well-established Hadamard matrix for 2D-NMR frequency encoding. In addition, a modified/improved solvent suppression approach is incorporated. This makes it possible to carry out the experiment with both polar and gradient eluents, the widely used chromatographic conditions. The method is example using a synthesized mixture of three amino acids (His, Phe and Try) and a human urine sample. The method demonstrated here may be utilized for high-throughput structural or unknown component identification and fast dynamic study in a variety of applications. PMID:17466317

Zhou, Zhiming; Lan, Wenxian; Zhang, Weinong; Zhang, Xu; Xia, Sheng'an; Zhu, Hang; Ye, Chaohui; Liu, Maili

2007-06-22

395

THIN-LAYER CHROMATOGRAPHY OF PYRIDINIUM ALDOXIMES USING DISTINCT TECHNIQUES FOR DEVELOPMENT  

Microsoft Academic Search

Twenty - two different pyridinium aldoximes were subjected to thin-layer chromatography using both classical chambers and also forced-flow technique for development. Running characteristics (such as RF values, time versus front distance) were compared in saturated and unsaturated chambers, and an OPLC. A comparison deals with developments in classical (capillary-flow) and modern (forced-flow) thin-layer chromatography.

Huba Kalász; Emil Mincsovics; Nazila Ram; Kamil Kuca

2010-01-01

396

Thin-layer chromatography: challenges and opportunities.  

PubMed

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, and (iv) bioactivity monitoring for selective detection. In combination with two-dimensional, multiple development and coupled column-layer separation techniques these core technologies could dramatically increase the use of thin-layer chromatography for the characterization of complex mixtures. It is also demonstrated that thin-layer chromatography has strong potential as a surrogate chromatographic model for estimating biopartitioning properties. To convert these opportunities into practice the current state-of-the-art of the core technologies is described and the principle obstacles to progress identified. PMID:12877208

Poole, Colin F

2003-06-01

397

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

398

Radial side (1D) tears.  

PubMed

The triangular fibrocartilage complex (TFCC) is the key structure at the wrist that facilitates the rotation of the radius and the carpus on the distal ulnar. The radial or type 1D tears of the TFCC are uncommon, but they pose a major disruption of the articular contact between the carpus and the distal ulna. The tears can heal by arthroscopically repairing the TFCC back to the radius using sutures through bone tunnels. This procedure allows patients to return to their work and sports activities with significant recovery of strength and range of motion. PMID:21871347

Trumble, Thomas

2011-08-01

399

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

400

Flow between contrarotating disks  

SciTech Connect

The paper describes a combined experimental and computational study of laminar and turbulent flow between contrarotating disks. Laminar computations produce Batchelor-type flow: radial outflow occurs in boundary layers on the disks and inflow is confined to a thin shear layer in the midplane; between the boundary layers and the shear layer, two contrarotating cores of fluid are formed. Turbulent computations (using a low-Reynolds-number {kappa}-{epsilon} turbulence model) and LDA measurements provide no evidence for Batchelor-type flow, even for rotational Reynolds numbers as low as 2.2 {times} 10{sup 4}. While separate boundary layers are formed on the disks, radial inflow occurs in a single interior core that extends between the two boundary layers; in the core, rotational effects are weak. Although the flow in the core was always found to be turbulent, the flow in the boundary layers could remain laminar for rotational Reynolds numbers up to 1.2 {times} 10{sup 5}. For the case of a superposed outflow, there is a source region in which the radial component of velocity is everywhere positive; radially outward of this region, the flow is similar to that described above. Although the turbulence model exhibited premature transition from laminar to turbulent flow in the boundary layers, agreement between the computed and measured radial and tangential components of velocity was mainly good over a wide range of nondimensional flow rates and rotational Reynolds numbers.

Gan, X.; Kilic, M.; Owen, J.M. [Univ. of Bath (United Kingdom). School of Mechanical Engineering

1995-04-01

401

Analyzing radial flow features in p-Pb and p-p collisions at several TeV by studying identified-particle production with the event generator EPOS3  

NASA Astrophysics Data System (ADS)

Experimental transverse momentum spectra of identified particles in p-Pb collisions at 5.02 TeV show many similarities to the corresponding Pb-Pb results, the latter ones usually being interpreted in terms of hydrodynamic flow. We analyze these data using epos3, an event generator based on a 3D+1 viscous hydrodynamical evolution starting from flux-tube initial conditions, which are generated in the Gribov-Regge multiple scattering framework. An individual scattering is referred to as Pomeron, identified with a parton ladder, eventually showing up as flux tubes (or strings). Each parton ladder is composed of a perturbative QCD hard process, plus initial- and final-state linear parton emission. Nonlinear effects are considered by using saturation scales Qs, depending on the energy and the number of participants connected to the Pomeron in question. We compute transverse momentum (pt) spectra of pions, kaons, protons, lambdas, and ? baryons in p-Pb and p-p scattering, compared to experimental data and many other models. In this way we show in a quantitative fashion that p-Pb data (and even p-p ones) show the typical "flow effect" of enhanced particle production at intermediate pt values, more and more visible with increasing hadron mass.

Werner, K.; Guiot, B.; Karpenko, Iu.; Pierog, T.

2014-06-01

402

Immunoelectrophoretic analysis and radial immunodiffusion assay using plasminogen purified from fresh human plasma  

PubMed Central

Plasminogen was purified from fresh human plasma by affinity chromatography and gel filtration and was characterized functionally, electrophoretically and on a weight basis. After antibody raised against this material was demonstrated to be monospecific for plasminogen/plasmin, it was employed in an immunoelectrophoretic analysis of plasminogen activated in several ways and in a radial immunodiffusion assay of human plasma plasminogen, where the mean level found was 476 ?g/ml. ImagesFIG. 5FIG. 8

Magoon, E. H.; Austen, K. F.; Spragg, Jocelyn

1974-01-01

403

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.

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

2012-01-01

404

Liquid Chromatography in 1982.  

ERIC Educational Resources Information Center

Reviews trends in liquid chromatography including apparatus, factors affecting efficient separation of a mixture (peak sharpness and speed), simplified problem-solving, adsorption, bonded phase chromatography, ion selectivity, and size exclusion. The current trend is to control chemical selectivity by the liquid phase. (Author/JN)

Freeman, David H.

1982-01-01

405

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

406

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

407

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

408

Large radial graded-index polymer  

NASA Astrophysics Data System (ADS)

A very large radial graded-index (GRIN) polymer was successfully prepared for the first time, to curved mold method and the diffusion copolymerization method. Both methods gave a radial GRIN polymer with a diameter of 70 mm and a Delta n value greater than 0.02. Ray tracing through these radial GRIN polymers was used to predict that such a GRIN polymer could be a promising candidate for thinner ophthalmic lenses with no spherical aberration or multifocusing characteristics.

Wu, Shang Pin; Nihei, Eisuke; Koike, Yasuhiro

1996-01-01

409

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

410

Two stages of visual processing for radial and circular motion  

NASA Astrophysics Data System (ADS)

As we move through our environment, the flow of the deforming images on our retinae provides rich information about ego motion and about the three-dimensional structure of the external world. Flow-fields comprise five independent compenents, including radial and circular motion1á¤-3. Here we provide psychophysical evidence for the existence of neural mechanisms in human vision that integrate motion signals along these complex trajectories. Signal-to-noise sensitivity for discriminating the direction of radial, circular and translational motion increased predictably with the number of exposed sectors, implying the existence of specialized detectors that integrate motion signals of different directions from different locations. However, contrast sensitivity for complex motion did not increase greatly with sector number, implying that the specialized detectors are preceded by a first stage of local-motion mechanisms that impose a contrast threshold. These findings fit well with recent electrophysiological evidence in monkey4á¤-7 showing that whereas motion-sensitive neurons in primary visual cortex respond best to local translation, many neurons in the medial superior temporal cortex have large receptive fields tuned to radial, circular or spiral motion.

Morrone, M. C.; Burr, David C.; Vaina, Lucia M.

1995-08-01

411

Radial transport in the central cell of the tandem mirror experiment  

Microsoft Academic Search

An experimental study of radial transport in the Tandem Mirror Experiment is reported here. Plasma parameters were measured in a series of well-diagnosed plasma discharges. A negative electric current (80±40 A within a 30-cm radius) flowed to the end wall, implying an equal radial loss of plasma ions. The axial losses of plasma ions were 100 A from the same

R. P. Drake; E. B. Hooper; C. V. Karmendy; S. L. Allen; T. A. Casper; J. F. Clauser; F. H. Coensgen; R. H. Cohen; D. L. Correll; J. C. Davis; J. H. Foote; A. H. Futch; R. K. Goodman; D. P. Grubb; G. E. Gryczkowski; G. A. Hallock; A. L. Hunt; W. E. Nexsen; W. L. Pickles; A. E. Pontau; P. Poulsen; T. C. Simonen; O. T. Strand; W. R. Wampler

1982-01-01

412

A novel approach for sensitivity calculations in the radial distribution system  

Microsoft Academic Search

In this paper, a novel approach for calculating the sensitivities of active\\/reactive power loss and voltage magnitudes with respect to active\\/reactive power injection at any bus in the radial distribution system is presented. In a radial distribution system, the changes in bus voltages and branch flows due to active\\/reactive power injection at any bus depend on the network topology. The

Dheeraj Kumar Khatod; Vinay Pant; Jaydev Sharma

2006-01-01

413

Capacitor Placement in Balanced and Unbalanced Radial Distribution System by Discrete Particle Swarm Optimization  

Microsoft Academic Search

Capacitor placement problem is a non-linear and non- differentiable mixed integer optimization problem with a set of equality and inequality constraints. Most conventional optimization techniques are incapable to solve this hard combinatorial problem. The radial distribution systems are unbalanced because of single-phase, two-phase and three-phase loads. Thus, load flow solution for balance radial distribution networks will not be sufficient to

S. Sivanagaraju; B. J. Viswanatha Rao

414

Abnormal radial artery in Down's syndrome.  

PubMed

Abnormal arterial patterns in the forearm were discovered in 12 of 77 patients (16%) with Down's syndrome. Eight patients had an enlarged anterior interosseous artery, the distal portion of which was palpable over the dorsum of the hand; in seven it was associated with absence of the radial artery and in one it coexisted with the radial and ulnar arteries. Three patients had a hypoplastic radial artery and a relatively dominant ulnar artery. One patient had a vestigial radial artery that ended as muscular branches in the forearm. The developmental aspects of these aberrations are discussed. PMID:2945516

Lo, R N; Leung, M P; Lau, K C; Yeung, C Y

1986-09-01

415

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

416

High performance stationary phases for planar chromatography.  

PubMed

The kinetic performance of stabilized particle layers, particle membranes, and thin films for thin-layer chromatography is reviewed with a focus on how layer characteristics and experimental conditions affect the observed plate height. Forced flow and pressurized planar electrochromatography are identified as the best candidates to overcome the limited performance achieved by capillary flow for stabilized particle layers. For conventional and high performance plates band broadening is dominated by molecular diffusion at low mobile phase velocities typical of capillary flow systems and by mass transfer with a significant contribution from flow anisotropy at higher flow rates typical of forced flow systems. There are few possible changes to the structure of stabilized particle layers that would significantly improve their performance for capillary flow systems while for forced flow a number of avenues for further study are identified. New media for ultra thin-layer chromatography shows encouraging possibilities for miniaturized high performance systems but the realization of their true performance requires improvements in instrumentation for sample application and detection. PMID:21056422

Poole, Salwa K; Poole, Colin F

2011-05-13

417

Cost-effective endoscopic radial artery harvesting.  

PubMed

Radial artery harvesting has been routinely performed by endoscopy. We present a reduced cost technique using a reusable retractor and thermal welding shears. The combination of reusable and disposable tools allows patients to benefit from endoscopic radial artery harvesting with decreased morbidity and favorable cosmetic results. PMID:16798258

Newman, Roxanne V; Lammle, W Greg; Matz, Kristy J

2006-07-01

418

Radial force in a bearingless reluctance motor  

NASA Astrophysics Data System (ADS)

A four-pole reluctance synchronous machine with additional two-pole windings was constructed. The additional winding currents produce the radial force to act as a magnetic bearing. Expressions for the machine inductance functions are given. Inductance functions with respect to the eccentric displacement of the rotor were measured. The contribution of these inductances to the radial force production is established.

Chiba, Akira; Rahman, M. A.; Fukao, Tadashi

1991-03-01

419

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

420

Excimer laser keratectomy after radial keratotomy.  

PubMed

Radial keratotomy to treat myopia has been characterized by a lack of predictability. Until recently, patients with undercorrected myopia who were unsatisfied with their visual outcome could only be offered secondary augmentation procedures, which were equally unpredictable. We performed excimer laser keratectomy in six eyes of five patients whose myopia was undercorrected after radial keratotomy. The average residual spherical equivalent refractive error after radial keratotomy was -2.40 diopters, and this was reduced to -0.48 diopters after laser treatment. Final uncorrected visual acuity ranged from 20/80 to 20/20, and visual acuity was corrected to within one line of the preoperative best-corrected value in all patients. Epithelialization of all eyes occurred within four to six days. There were no incidences of corneal neovascularization, including no vascularization of the radial keratotomy incisions. Our findings suggest excimer phototherapeutic keratectomy offers a safe and more controlled method of augmenting undercorrected myopia after radial keratotomy. PMID:8488917

Frangie, J P; Park, S B; Kim, J; Aquavella, J V

1993-05-15

421

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

422

Performance of radial clearance rim seals in upstream and downstream rotor-stator wheelspaces  

NASA Astrophysics Data System (ADS)

A new experimental facility for the investigation of rim sealing is described, and measurements are presented for two representative radial clearance seals with a nominally axisymmetric external flow. One radial seal has an upward rotor lip and is upstream of the rotor while the other has an upward stator lip and is downstream of the rotor. Measurements include surface pressures, tangential velocities in the core region of the disk cavity flow, and traverses of gas concentration in the cavity showing the distribution of mainstream ingestion. Tests were conducted at rotational Reynolds numbers up to 3 x 10 exp 6 with nominal seal clearance to radius ratios in the range 0.002 to 0.01. For the radial seals, a differential pressure criterion is found to overestimate the minimum sealing flow. Tangential velocity measurements in the wheelspace are in excellent agreement with other measurements and theoretical predictions.

Dadkhan, S.; Turner, A. B.; Chew, J. W.

1991-06-01

423

Radial Force Balance in Plasma Hole and Role of Centrifugal Force  

NASA Astrophysics Data System (ADS)

A large-scale monopole vortex has been observed in a cylindrical magnetized plasma produced in the HYPER-I device at National Institute for Fusion Science, Japan. It is spontaneously formed with a deep density hole in its core and is referred to as plasma hole from the impression of the end-view image taken by a CCD camera. The flow-velocity field of the plasma hole exhibits two characteristic features: a supersonic azimuthal rotation caused by a strong radial electric field and an inward radial flow. Since the latter is not driven in axisymmetric collisionless invicid plasma, it implies finite viscosity of the plasma. It is revealed that quasi-neutrality breaking (?n/n˜10-3), which is the source of strong electric field, occurs in the hole region. To develop a deeper understanding on the structure of the flow-velocity field, we have analyzed the radial force balance including the nonlinear terms, i.e. the dynamic pressure due to radial flow and the centrifugal force. It is found that the centrifugal force dominates the radial electric field in the hole region, giving rise to a rigid rotor equilibrium which is similar to the fast rotation mode realized in pure electron plasmas.

Yoshimura, Shinji; Kono, Mitsuo; Tanaka, Masayoshi

2006-10-01

424

Reestablished circulation after free radial forearm flap transfer.  

PubMed

New circulation in the free flap reestablished at the recipient site is the key to successful microvascular reconstructive surgery. This study is the first evaluation of long-term circulatory changes in nine free radial forearm flap transfers. Postoperatively, color Doppler studies revealed that the flow volume through the arterial pedicle increased rapidly during the first 3 days, gradually increased until day 14 (exceeding flow volume through the facial artery of the unoperated contralateral side), then decreased slightly until the sixth month. The pulsatility index, representing vascular resistance downstream, decreased successively. Ohm's law explains that this flow increase is caused by reduced vascular resistance downstream, attributed to changes in the vascularity of the transferred flap and in the recipient bed. The authors believe the circulatory changes are determinants of the clinical properties of the flap. This study addresses the importance of clarifying the events that transpire at the macroscopic circulatory level in the transferred free flap. PMID:15088205

Ichinose, Akihiro; Tahara, Shinya; Terashi, Hiroto; Yokoo, Satoshi

2004-04-01

425

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.

2011-05-12

426

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

427

A Simple Algorithm to Implement Active Power Loss Allocation Schemes in Radial Distribution Systems  

NASA Astrophysics Data System (ADS)

In this paper, a brief overview of various active power loss allocation methods is presented. "Exact Method" of loss allocation, suitable for radial distribution systems, is chosen for implementation. Simple bus identification techniques are proposed to implement load flow and loss allocation. A detailed algorithm with some useful MATLAB codes are included to form various proposed arrays to perform the load flow and then allocate losses to various buses. The results for a 30-bus and a 69-bus radial test distribution system are presented.

Mishra, S.; Das, D.; Paul, S.

2012-09-01

428

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

429

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, may be a significant factor in seal operating mechanism.

Etsion, I.

1978-01-01

430

Simulation and theory of radial equilibrium of plasmoid propagation  

SciTech Connect

Cases simulating beam currents to about 29 MA were done. Significant noise reduction and code speed-up were achieved for these cases. The net current scaling observed at lower beam current (I{sub net} {approximately} I{sub beam}{sup 1/2}) continued to hold up well, as did the equilibrium itself. A slight deviation in the expected thickness and radial structure of the current layer was observed, however. A laminar flow model is developed that appears to give good agreement with the simulation results. Suggestions for future work are discussed briefly.

Campbell, M.M.; Clark, R.M.; Mostrom, M.A.

1989-09-01

431

Heat transfer in cooled guide vanes. [of radial inflow turbine  

NASA Technical Reports Server (NTRS)

A numerical study to determine the temperature distribution in the guide vanes of a radial inflow turbine is presented. A computer program has been developed to calculate the temperature distribution when the vanes are cooled internally using a combination of impingement and film cooling techniques. The study is based on the use of the finite difference method in a two dimensional heat conduction problem. The results are then compared to determine the best cooling configuration for a certain coolant to primary mass flow ratio.

Tabakoff, W.; Kotwal, R.; Hamed, A.

1977-01-01

432

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.

433

Experimental Radial Density Profiles in Wire Array Z-Pinches  

NASA Astrophysics Data System (ADS)

The ablation processes occurring in wire arrays are fundamental to the evolution of the radial density profile, the development of precursor structures, and the trajectory of the final implosion of the main array mass. During the flow of plasma to the array axis, a quasi-periodic axial modulation in the density is observed experimentally for all array materials. The wavelength of this `flare' structure varies with material, but the mechanism which seeds the development of this axial modulation axis remains unresolved. This is often introduced into numerical simulations by artificially by use of either an initial axial mass or temperature variation at the appropriate periodicity in order to emulate the experiment. Experimental characterization of the evolution of the radial density profile will provide a constraint for the initial conditions of the simulation. This paper describes radiographic and interferometric data from wire array experiments on the MAGPIE generator at Imperial College London. In particular, two-frame radiography is applied to image a single wire core at multiple times to study the development of the radial flare structure, and these data are compared to results from the Gorgon 3D MHD code. This research was sponsored by the NNSA under DOE Cooperative Agreement DE-F03-02NA00057.

Bott, Simon; Lebedev, S.; Bland, S.; Chittenden, J.; Haines, M.; Hall, G.; Rapley, J.; Suzuki, F.; Marocchino, A.; Palmer, J.; Ampleford, D.; Jennings, C.

2006-10-01

434

Spectral distortion in a radially inhomogeneous cosmology  

NASA Astrophysics Data System (ADS)

The spectral distortion of the cosmic microwave background blackbody spectrum in a radially inhomogeneous space-time, designed to exactly reproduce a ?CDM expansion history along the past light cone, is shown to exceed the upper bound established by COBE-FIRAS by a factor of approximately 3700. This simple observational test helps uncover a slew of pathological features that lie hidden inside the past light cone, including a radially contracting phase at decoupling and, if followed to its logical extreme, a naked singularity at the radially inhomogeneous big bang.

Caldwell, R. R.; Maksimova, N. A.

2013-11-01

435

Thermal diffusivity measurements at high temperatures by the radial flash method  

NASA Astrophysics Data System (ADS)

The flash method has been extended to measure thermal diffusivity in the radial direction at high temperatures, and in the presence of substantial radiation heat losses. Radial effects in this instance, arise because only a small portion of the front surface of the sample is exposed to the energy source. The present effort complements a recently published study in which thermal diffusivity was measured in the axial direction. In that study, substantial radial heat flow and axial radiation heat losses were experienced. Both methods were used to test the same samples of an isotropic material (POCO AXM-5Q graphite) and an anisotropic material (reactor-grade graphite). Results show that thermal diffusivity in the radial direction can be measured for both isotropic and anisotropic material without accounting for the large radiation heat losses. These results are also compared with those based on the conventional flash method using smaller samples.

Chu, F. I.; Taylor, R. E.; Donaldson, A. B.

1980-01-01