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1

Electrokinetic effects near a membrane  

NASA Astrophysics Data System (ADS)

We discuss the electrostatic and electrokinetic contribution to the elastic moduli of a cell or artificial membrane placed in an electrolyte and driven by a DC electric field. The field drives ion currents across the membrane, through specific channels, pumps or natural pores. In steady state, charges accumulate in the Debye layers close to the membrane, modifying the membrane elastic moduli. We first study a model of a membrane of zero thickness, later generalizing this treatment to allow for a finite thickness and finite dielectric constant. Our results clarify and extend the results presented in [D. Lacoste, M. Cosentino Lagomarsino, and J. F. Joanny, Europhys. Lett., 77, 18006 (2007)], by providing a physical explanation for a destabilizing term proportional to kps^3 in the fluctuation spectrum, which we relate to a nonlinear (E^2) electro-kinetic effect called induced-charge electro-osmosis (ICEO). Recent studies of ICEO have focused on electrodes and polarizable particles, where an applied bulk field is perturbed by capacitive charging of the double layer and drives flow along the field axis toward surface protrusions; we predict similar ICEO flows around driven membranes, due to curvature-induced tangential fields within a non-equilibrium double layer, which hydrodynamically enhance protrusions.

Lacoste, David

2009-03-01

2

Electrokinetic effects in power transformers  

SciTech Connect

The behavior of dielectric fluids used for the cooling and insulation of power system equipment is significantly influenced by motion enforced by the action of circulating pumps. Not only can charges generated by streaming electrification accumulate to distort the electric field in positions where dielectric integrity is prejudiced, but the dielectric strength of the fluid is also altered per se by the actions of the flow in a complex, but predictable manner. Three important electrokinetic effects in transformer oil subjected to forced circulation are experimentally investigated using laboratory model ducts. Careful breakdown measurements with sustained voltage on flowing fluids have been extended to pulse voltages with a view to establishing the nature of time dependencies. The use of Schlieren optics on the duct has also demonstrated that flow patterns are modified by the imposition of electric fields through electrohydrodynamic (EHD) effects. Present model studies invite speculation that not only streaming electrification but also forced circulation per se may prejudice dielectric structure in power system equipment and these effects need to be understood to permit informed design and safe operation. These models are discussed in this paper. 122 refs., 82 figs., 10 tabs.

Nelson, J.K.; Lee, M.J. (Rensselaer Polytechnic Inst., Troy, NY (USA). Dept. of Electric Power Engineering)

1990-06-01

3

Electrokinetic effects by the electric work method  

Microsoft Academic Search

The electric work method is used to derive new expressions for electrokinetic effects produced by flowing fluids. The expressions are functions of channel geometry. The results are obtained from an equation of motion by superposition of reversible and irreversible phenomena. The equation of motion is an extended Navier-Stokes equation. The momentum transference factors, which describe the reversible conversion between mechanical

H. Gerhard Hertz; Signe Kjelstrup Ratkje

1996-01-01

4

Study of electrokinetic effects to quantify groundwater flow  

SciTech Connect

An experimental study of electrokinetic effects (streaming potential) in earth materials was undertaken. The objective was to evaluate the measurement of electrokinetic effects as a method of monitoring and predicting the movement of groundwater, contaminant plumes, and other fluids in the subsurface. The laboratory experiments verified that the electrokinetic effects in earth materials are prominent, repeatable, and can be described well to first order by a pair of coupled differential equations.

Brown, S.R. [Sandia National Lab., Albuquerque, NM (United States); Haupt, R.W. [MIT Lincoln Lab., Lexington, MA (United States)

1997-04-01

5

Effects of electrostatic correlations on electrokinetic phenomena  

NASA Astrophysics Data System (ADS)

The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper considers situations, such as concentrated electrolytes, multivalent electrolytes, or solvent-free ionic liquids, where the mean-field approximation breaks down. A fourth-order modified Poisson equation is developed that captures the essential features in a simple continuum framework. The model is derived as a gradient approximation for nonlocal electrostatics of interacting effective charges, where the permittivity becomes a differential operator, scaled by a correlation length. The theory is able to capture subtle aspects of molecular simulations and allows for simple calculations of electrokinetic flows in correlated ionic fluids. Charge-density oscillations tend to reduce electro-osmotic flow and streaming current, and overscreening of surface charge can lead to flow reversal. These effects also help to explain the suppression of induced-charge electrokinetic phenomena at high salt concentrations.

Storey, Brian D.; Bazant, Martin Z.

2012-11-01

6

Electrokinetic effects on detection time of nanowire biosensor  

PubMed Central

We develop a multiphysics model to study the contribution of electrokinetics on the biomolecular detection process and provide a physical explanation of the two to three orders of magnitude difference in detection time between experimental results and theoretical predications at ultralow concentration. The electrokinetic effects, including electrophoretic force and electroosmotic flow, have been systematically studied under various sensor design and test conditions. In a typical single nanowire-based sensor, it is found that electrokinetic effects could result in a reduction of detection time over 90 times, compared with that induced by pure biomolecular diffusion. The detection time difference is further enhanced by increasing the applied gate voltage or the number of nanowires. It is proposed that accelerated biomolecular detection at ultralow concentration could be achieved by appropriate combinations of electrokinetic effects and nanowire sensor design.

Liu, Yaling; Guo, Qingjiang; Wang, Shunqiang; Hu, Walter

2012-01-01

7

Electrokinetic effects on detection time of nanowire biosensor  

NASA Astrophysics Data System (ADS)

We develop a multiphysics model to study the contribution of electrokinetics on the biomolecular detection process and provide a physical explanation of the two to three orders of magnitude difference in detection time between experimental results and theoretical predications at ultralow concentration. The electrokinetic effects, including electrophoretic force and electroosmotic flow, have been systematically studied under various sensor design and test conditions. In a typical single nanowire-based sensor, it is found that electrokinetic effects could result in a reduction of detection time over 90 times, compared with that induced by pure biomolecular diffusion. The detection time difference is further enhanced by increasing the applied gate voltage or the number of nanowires. It is proposed that accelerated biomolecular detection at ultralow concentration could be achieved by appropriate combinations of electrokinetic effects and nanowire sensor design.

Liu, Yaling; Guo, Qingjiang; Wang, Shunqiang; Hu, Walter

2012-04-01

8

An integrated method incorporating sulfur-oxidizing bacteria and electrokinetics to enhance removal of copper from contaminated soil  

SciTech Connect

The combination of bioleaching and electrokinetics for the remediation of metal contaminated land has been investigated. In bioleaching, bacteria convert reduced sulfur compounds to sulfuric acid, acidifying soil and mobilizing metal ions. In electrokinetics, DC current acidifies soil, and mobilized metals are transported to the cathode by electromigration. When bioleaching was applied to silt soil artificially contaminated with seven metals and amended with sulfur, bacterial activity was partially inhibited and limited acidification occurred. Electrokinetic treatment of silt soil contaminated solely with 1000 mg/kg copper nitrate showed 89% removal of copper from the soil within 15 days. To combine bioleaching and electrokinetics sequentially, preliminary partial acidification was performed by amending copper-contaminated soil with sulfur (to 5% w/w) and incubating at constant moisture (30% w/w) and temperature (20 C) for 90 days. Indigenous sulfur oxidizing bacteria partially acidified the soil from pH 8.1 to 5.4. This soil was then treated by electrokinetics yielding 86% copper removal in 16 days. In the combined process, electrokinetics stimulated sulfur oxidation, by removing inhibitory factors, yielding a 5.1-fold increase in soil sulfate concentration. Preacidification by sulfur-oxidizing bacteria increased the cost-effectiveness of the electrokinetic treatment by reducing the power requirement by 66%.

Maini, G.; Sharman, A.K.; Sunderland, G.; Knowles, C.J.; Jackman, S.A.

2000-03-15

9

Electrokinetic remediation of concrete: effect of chelating agents.  

PubMed

Contamination of concrete at various nuclear power plants and spent nuclear fuel reprocessing facilities by radionuclides represents a significant problem for the world's nuclear power industries and nuclear waste management. The present publication summarizes the most recently published data on Electrokinetic Remediation (EK) of various concrete installations and advantageous effects of the combination of EK with different chelating agents. The specific aspects of decontamination of concrete and mortar surfaces are analyzed, such as: (a) effect of chelating agents (EDTA, citric acid), (b) effect of the zeta-potential (zeta) of concrete surface, (c) effects of sorption and complex formation equilibrium, and (d) specific advantages and problems of the electrokinetic decontamination process. The results of laboratory and in situ tests of chelating agent assisted EK removal of radionuclides are reported. It is demonstrated that the correct combination of EK with specific chelating agents can be effectively employed for decontamination of concrete surfaces. PMID:18313182

Popov, K; Glazkova, I; Yachmenev, V; Nikolayev, A

2008-03-03

10

Modeling Electrokinetic Effect in Biomolecule Detection by Nanosensors  

NASA Astrophysics Data System (ADS)

In recent years, many types of sensors using nanotechnology, such as SPR, planar electrodes, nanowires, nanotips, and nanospheres, are being developed to provide the needed ultrasensitivity. Despite the significant progress achieved in biosensors, the fundamental understanding of biosensor detection process and bio-nano interfacial interaction at such low concentrations is very limited, which has hindered the interpretation of experimental results as well as sensor design. We will provide a physical and statistical interpretation of fM nanosensor detection process through a Brownian adhesion dynamics approach. Various electrokinetic effects are explored and found to contribute to fast biomolecule detection at ultralow concentration.

Liu, Yaling; Wang, Shunqiang; Hu, Walter

2012-02-01

11

Joule heating effects on electrokinetic focusing and trapping of particles in constriction microchannels  

NASA Astrophysics Data System (ADS)

Joule heating (JH) is a ubiquitous phenomenon in electrokinetic microfluidic devices. Its effects on fluid and ionic species transport in capillary and microchip electrophoresis have been well studied. However, JH effects on the electrokinetic motion of microparticles in microchannels have been nearly unexplored in the literature. This paper presents an experimental investigation of JH effects on electrokinetic particle transport and manipulation in constriction microchannels under both pure dc and dc-biased ac electric fields. It is found that the JH effects reduce the dielectrophoretic focusing and trapping of particles, especially significant when dc-biased ac electric fields are used. These results are expected to provide a useful guidance for future designs of electrokinetic particle handling microdevices that will avoid JH effects or take advantage of them.

Zhu, Junjie; Sridharan, Sriram; Hu, Guoqing; Xuan, Xiangchun

2012-07-01

12

An integrated method incorporating sulfur-oxidizing bacteria and electrokinetics to enhance removal of copper from contaminated soil  

Microsoft Academic Search

The combination of bioleaching and electrokinetics for the remediation of metal contaminated land has been investigated. In bioleaching, bacteria convert reduced sulfur compounds to sulfuric acid, acidifying soil and mobilizing metal ions. In electrokinetics, DC current acidifies soil, and mobilized metals are transported to the cathode by electromigration. When bioleaching was applied to silt soil artificially contaminated with seven metals

Giacomo Maini; Ajay K. Sharman; Garry Sunderland; Christopher. J. Knowles; Simon A. Jackman

2000-01-01

13

Micromixer utilizing electrokinetic instability-induced shedding effect.  

PubMed

This paper presents a T-shaped micromixer featuring 45 degrees parallelogram barriers (PBs) within the mixing channel. The presented device obtains a rapid mixing of two sample fluids with conductivity ratio of 10:1 (sample concentration:running buffer concentration) by means of the electrokinetic instability-induced shedding effects which are produced when a direct current (DC) electric field of an appropriate intensity is applied. The presented device uses a single high-voltage power source to simultaneously drive and mix the sample fluids. The effectiveness of the mixer is characterized experimentally as a function of the applied electrical field intensity and the extent to which the PBs obstruct the mixing channel. The experimental results indicate that the mixing performance reaches 91% at a cross-section located 2.3 mm downstream of the T-junction when the barriers obstruct 4/5 of the channel width and an electrical field of 300 V/cm is applied. The micromixing method presented in this study provides a simple low-cost solution to mixing problems in lab-on-a-chip systems. PMID:17109376

Tai, Chang-Hsien; Yang, Ruey-Jen; Huang, Min-Zhong; Liu, Chia-Wei; Tsai, Chien-Hsiung; Fu, Lung-Ming

2006-12-01

14

Enhanced remediation of Cr(VI)-contaminated soil by incorporating a calcined-hydrotalcite-based permeable reactive barrier with electrokinetics.  

PubMed

This paper describes the enhanced Cr(VI)-contaminated soil remediation via a combination of electrokinetics (EK) with a calcined-hydrotalcite-based permeable reactive barrier (PRB). First, this combination proved to be feasible, and remarkably facilitated Cr(VI) remediation in a column test. Then, lightly-to-severely (0.16-1.65 mg/g) Cr(VI)-contaminated soil was remediated in a simulated test with the calcined hydrotalcite as the PRB under an voltage of 10-30 V (i.e. an electric field intensity of 0.7-2.0 V/cm). The observations demonstrated that both PRB and EK are critical to efficient remediation and the high de-contamination efficiency is supposedly attributed to the synergistic effect, for which EK concentrates anionic chromate to the anode region and PRB media (calcined hydrotalcite) absorbs and immobilizes it. Thus we have shown that the combined PRB-EK system is highly adaptive and effective in remediation of a larger area contaminated with chromate and various anionic pollutants. PMID:22985820

Zhang, Jia; Xu, Yunfeng; Li, Wentao; Zhou, Jizhi; Zhao, Jun; Qian, Guangren; Xu, Zhi Ping

2012-08-25

15

Sludge dewatering by electrokinetic technique: effect of processing time and potential gradient  

Microsoft Academic Search

A sludge cake (87.8% of moisture content) from a wastewater treatment plant was used to investigate the effects of processing time and potential gradient on the water removal by an electrokinetic (EK) process. A potential gradient ranging from 2.5 to 5.0 V\\/cm was applied to induce the movement of bound water within the sludge specimen for a time period of

Ching Yuan; Chih-huang Weng

2003-01-01

16

Effects of triethyl phosphate and nitrate on electrokinetically enhanced biodegradation of diesel in low permeability soils.  

PubMed

Bench-scale experiments for electrokinetically enhanced bioremediation of diesel in low permeability soils were conducted. An electrokinetic reactor (ER) was filled with kaolin that was artificially contaminated with diesel at a level of 2500 mg kg(-1). A constant voltage gradient of 1.0 V cm(-1) was applied. In phosphorus transport experiments, KH2PO4 was not distributed homogeneously along the ER, and most of the transported phosphorus was converted to water-insoluble aluminum phosphate after 12 days of electrokinetic (EK) operation. However, the advancing P front of triethyl phosphate (TEP) progressed with time and resulted in uniform P distribution. The treatments employed in the electrokinetically enhanced bioremediation of diesel were control (no addition of nitrogen and phosphorus), NP (KNO3+ KH2PO4), NT (KNO3+ TEP), UP (urea+ KH2PO4), and UT (urea+TEP). Analysis of effluent collected during the first 12 days of EK operation showed that diesel was not removed from the kaolin. After nutrient delivery, using the EK operation, the ER was transferred into an incubator for the biodegradation process. After 60 days of biodegradation, the concentrations of diesel in the kaolin for the NP, NT, UP, UT, and control treatments were 1356, 1002, 1658, 1612, and 2003 mg kg(-1), respectively. The ratio of biodegraded diesel concentration to initial concentration (2465 mg kg(-1)) in NP, NT, UP, UT, and control were 45.0%, 59.4%, 32.7%, 34.6%, and 18.7%, respectively. This result showed that TEP, treated along with NO3-, was most effective for the biodegradation of diesel. TEP was delivered more efficiently to the target zones and with less phosphorus loss than KH2PO4. However, this facilitated phosphorus delivery was effective in biodegrading diesel under anaerobic conditions only when electron acceptors, such as NO3-, were present. PMID:17879844

Lee, G T; Ro, H M; Lee, S M

2007-08-01

17

[Teratogenic effects of incorporated radionuclides].  

PubMed

Experimental data on teratogenic effects induced by incorporated alpha, beta and gamma-emitters were analyzed. It was found that the radioactive substances as well as external irradiation induced teratogenic effects. Teratogenesis caused by incorporated radionuclides has some peculiarities compared to the effect caused by fetus exposure to external radiation. These peculiarities are related to the fact of the limited penetration of incorporated radionuclides via placenta barrier so the radiation fetal doses are accumulated within long period of time and radiation dose rates are relatively low. The exposure to incorporated radionuclides does not induce severe developmental defects. Most frequent developmental defects of fetus include its death, general retardation of the development and growth. In such case the earlier pregnancy term was affected by radionuclide the more severe fetal damages occur in fetus because of the gradual increase of absorbed dose even in case of single intake of radionuclide. RBEs of radionuclides if compared to that for external gamma radiation are evaluated as follows: 2-4 (tritium oxide), 20 (241Am), 50 (238Pu) and 3-5 (131I in thyroid). PMID:11898639

Liaginskaia, A M; Osipov, V A

18

Removal of Pb from sewage sludge by electrokinetics: Effect of pH and washing solution type  

Microsoft Academic Search

In this study, the effect of pH and washing solution on the removal of lead from sewage sludge by electrokinetics was investigated. The six experimental runs were carried out at two different pH values – 3 and 4 – using acetic acid, nitric acid and phosphoric acid. In addition, the sequential chemical extraction scheme according to the BCR’s (Community Bureau

Özge Hanay; Halil Hasar; Nilufer Nacar Koçer; Ozgur Ozdemir

2009-01-01

19

Analysis of effect of electrolyte types on electrokinetic energy conversion in nanoscale capillaries.  

PubMed

An analytical study on the effect of electrolyte types on the electrokinetic energy conversion is presented using nanoscale cylindrical capillary, which is either positively or negatively charged. The sign of surface charge determines the role and concentration magnitude of ions in the capillary and the energy conversion performance. Our study shows that the electrokinetic energy conversion performance (maximum efficiency, pressure rise and streaming potential) are approximately identical for 1:1 (KCl), 2:1 (CaCl2) and 3:1 (LaCl3) electrolytes when capillary is positively charged. For negatively charged capillary, energy conversion performance degrades significantly with the increase of counter-ion valence. For both positively and negatively charged capillaries, higher maximum efficiency can be resulted in low bulk concentration and surface charge density regimes. However, high maximum pressure rise generation for the pumping is found in the low bulk concentration and high surface charge density regimes. For the electric power generation, higher maximum streaming potential is found when both bulk concentration and surface charge density are low. PMID:20119963

Chein, Reiyu; Tsai, Kunyong; Yeh, Liying

2010-01-01

20

Transient effects on microchannel electrokinetic filtering with an ion-permselective membrane.  

PubMed

The electrokinetics and hydrodynamics in a hybrid microfluidic/nanofluidic pore network configuration and its effect on the concentration enrichment of charged analytes are described. A hydrogel microplug, photopolymerized in a microfluidic channel, with negative surface charge serves as a nanoporous membrane and dictates the electrokinetic behavior within the adjoining microchannel compartments. The nanoporous hydrogel with a mean pore size on the order of the electrical double layer thickness imparts ion-permselectivity (cation-selectivity) to the migration of ionic species which, under the influence of an applied electrical field, drives concentration polarization in bulk solution near the interfaces between the two microchannel compartments and the hydrogel-based nanopores. The concentration enrichment efficiency for charged analytes depends on this concentration polarization, which strongly affects the distribution of local electrical field strength. In addition, electroosmotic flow in the device plays a critical role in determining the location of the analyte enrichment zone. A theoretical model and simulations are presented to explain the interplay of concentration polarization and electroosmotic flow with respect to the observed concentration enrichment of negatively charged analytes at the cathodic hydrogel plug-microchannel solution interface. PMID:18197694

Dhopeshwarkar, Rahul; Crooks, Richard M; Hlushkou, Dzmitry; Tallarek, Ulrich

2008-01-16

21

Immobilized enzymes: Electrokinetic effects on reaction rates under external diffusion.  

PubMed

The rates of reactions catalyzed by enzymes immobilized on a nonporous solid surface have been computed employing a Nernst film model. The Nernst-Planck equations for the transport of the charged substrate and product species in the film and the Poisson equation for the distribution of electrical potential are solved numerically with the appropriate boundary conditions. The electrical charge at the surface is assumed to arise from the dissociation equilibria of the acidic and basic surface groups of the enzyme. The pH at the surface affects both the surface charge as well as the intrinsic kinetics of the enzyme-catalyzed reaction. Factors which determine the pH at the surface include the pH in the bulk solution and the release of H(+) ions in the enzyme-catalyzed reaction. The latter causes a lowering of pH at the surface, causing the reaction rate to differ from that computed assuming an equilibrium distribution of electrical potential. Another kind of nonequilibrium contribution is caused by unequal charges or diffusivities of the substrate and products, which results in a diffusion potential being set up. Two moduli are introduced to evaluate the significance of the reaction-generated lowering of pH and the diffusion potential effect. The effect of changing various parameters, e.g., reaction rate constant, substrate concentration, enzyme concentration, pH, etc., on the overall reaction rate are studied. PMID:18546127

Kalthod, D G; Uckenstein, E

1982-10-01

22

Electrokinetic pump  

DOEpatents

A method for altering the surface properties of a particle bed. In application, the method pertains particularly to an electrokinetic pump configuration where nanoparticles are bonded to the surface of the stationary phase to alter the surface properties of the stationary phase including the surface area and/or the zeta potential and thus improve the efficiency and operating range of these pumps. By functionalizing the nanoparticles to change the zeta potential the electrokinetic pump is rendered capable of operating with working fluids having pH values that can range from 2-10 generally and acidic working fluids in particular. For applications in which the pump is intended to handle highly acidic solutions latex nanoparticles that are quaternary amine functionalized can be used.

Patel, Kamlesh D. (Dublin, CA)

2007-11-20

23

Electrokinetic Power Generation from Liquid Water Microjets  

SciTech Connect

Although electrokinetic effects are not new, only recently have they been investigated for possible use in energy conversion devices. We have recently reported the electrokinetic generation of molecular hydrogen from rapidly flowing liquid water microjets [Duffin et al. JPCC 2007, 111, 12031]. Here, we describe the use of liquid water microjets for direct conversion of electrokinetic energy to electrical power. Previous studies of electrokinetic power production have reported low efficiencies ({approx}3%), limited by back conduction of ions at the surface and in the bulk liquid. Liquid microjets eliminate energy dissipation due to back conduction and, measuring only at the jet target, yield conversion efficiencies exceeding 10%.

Duffin, Andrew M.; Saykally, Richard J.

2008-02-15

24

Electric Potential Variations on a Poplar: Beyond Electrokinetic Effects Associated With Sap Flow  

NASA Astrophysics Data System (ADS)

Electric potential has been monitored since December 2003 in the roots and at two circumferences and one vertical profile in a standing poplar (Populus incognitus). Electric potential is sampled using 5 mm diameter stainless steel rods, inserted 5 mm deep in the cambium, and is referenced to an unpolarizable Petiau electrode installed 80 cm deep in the soil. Various types of signals are observed. Transient signals with long relaxation times affecting some electrodes simultaneously, may be contact potentials triggered by condensation and evaporation. Diurnal variations are observed which present a seasonal variation. During winter, diurnal variations depend on the measurement point, with variable amplitudes and sometimes anticorrelations between electrodes. By contrast, a stable and coherent organization is established in the spring, with larger amplitudes, and lasts during summer. Such signals have been reported previously (Koppan et al., 2000; Morat et al., 1994; Fensom, 1963), have been interpreted as electrokinetic effects associated with sap flow. However, a comparison of the electrical signals with a measurement of the sap flow by a heat flow method, shows that the electrical variation, although clearly correlated to sap flow, is not simply proportional to it. In a living system, electrokinetic effects, in addition to thermoelectrical effects, are probably modified significantly by additional electrochemical effects, such as membrane diffusion potentials, ion active transport by proteins, and action potentials. Such effects have been evidenced in laboratory experiments with plants (e.g., Fromm and Hei, 1998). Electric potential variations in trees may thus reveal mechanisms not accessible by other methods, and maybe reveal new aspects of the physics of living systems. A better understanding of the electrical response of trees to meteorological, chemical or biological forcing may improve the knowledge of transfer processes between the soil and the atmosphere. This is important for the modeling of water and carbon balance in relation to climate change, as well as of the contribution of trees to the migration, retention and dispersion of contaminants. Fensom, D. S., The bioelectric potentials of plants and their functional significance : V. Some daily and seasonal changes in the electrical potential and resistance of living trees, Canadian J. Botany, 41, 831-851, 1963. Fromm, J., and H. Fei, Electrical signaling and gas exchange in maize plants of drying soil, Plant Science, 132, 203-213, 1998. Koppan, A., L. Szarka, and V. Wesztergom, Annual fluctuation in amplitudes of daily variations of electrical signals measured in the trunk of a standing tree, C. R. Acad. Sci. Paris, 323, 559-563, 2000. Morat, P., J.-L. Le Mouël, and A. Granier, Electrical potential on a tree. A measurement of the sap flow ?, C. R. Acad. Sci. Paris, 317, 98-101, 1994.

Gibert, D.; Le Mouël, J.; Lambs, L.; Nicollin, F.; Conil, F.; Perrier, F.

2004-12-01

25

ELECTROKINETIC SOIL PROCESSING COMPLICATING FEATURES OF ELECTROKINETIC REMEDIATION OF SOILS AND SLURRIES: SATURATION EFFECTS AND THE ROLE OF THE CATHODE ELECTROLYSIS  

Microsoft Academic Search

Electrokinetic soil processing is an emerging technology for decontamination of certain radionuclides, heavy metals, or organic species from soils or slurries. Tests reveal that the process efficiencies in partially saturated kaolinite samples (without contaminants) are high, since water supplied at the anode eventually flushed across the specimens and saturated the deposits. Consolidation settlements are expected in the vicinity of anodes

A. UGAZ; S. PUPPALA; R. J. GALE; Y. B. ACAR

1994-01-01

26

Effect of class I and II organic modifiers on retention and selectivity in vesicle electrokinetic chromatography.  

PubMed

Vesicles are large aggregates of surfactant monomers consisting of a spherical bilayer surrounding an internal cavity of solvent. The bilayer structure allows vesicles to be attractive models for the study of various transmembrane and binding processes. The use of thermodynamically stable vesicles (TSV) formed from oppositely charged surfactants for use as a pseudostationary phase in electrokinetic chromatography (EKC) was first accomplished using dodecyltrimethylammonium bromide and sodium dodecyl sulfate (DTAB/SDS). Surfactant vesicles have demonstrated enhanced separation characteristics compared to conventional micelles in EKC, although only investigated in aqueous media. Organic modifiers have been widely studied and used in EKC to enhance separation conditions. In this study, vesicles formed from cetyltrimethylammonium bromide and sodium octyl sulfate (CTAB/SOS) were investigated in the presence of "class I and II" organic modifiers. Electrophoretic and chromatographic parameters were examined as well as linear solvation energy relationship analysis (LSER) to characterize the effects of the modifiers on retention and selectivity in EKC. LSER analysis is a useful way to quantitatively investigate solute/solvent interactions responsible for retention and selectivity. PMID:12179980

Pascoe, Robert; Foley, Joe P

2002-06-01

27

Effects of electrokinetic treatment of a heavy metal contaminated soil on soil enzyme activities  

Microsoft Academic Search

There is a growing concern on the potential application of a direct current (DC) electric field to soil for removing contaminants, but little is known about its impact on soil enzyme activities. This study investigated the change of enzyme activities of a heavy metal contaminated soil before and after electrokinetic (EK) treatments at lab-scale and the mechanisms of EK treatment

Long Cang; Dong-Mei Zhou; Quan-Ying Wang; Dan-Ya Wu

2009-01-01

28

Electrokinetics in undeveloped flows.  

PubMed

For the correct interpretation of results of tangential electrokinetic measurements with porous materials, in particular, composite/asymmetric membranes on porous supports, it is necessary to have the data available for various channel heights. In some kinds of equipment, the variation of channel height is technically possible only for a range of relatively large heights. This communication shows that under these conditions, the fluid flow can become undeveloped and the conventional approaches to the interpretation of electrokinetic measurements should be modified accordingly. In particular, the dependence of streaming-current coefficient on the channel height becomes sub-linear. If the experimental data are available only for larger channel heights, this can be mistakenly taken for the manifestation of contribution of porous sub-structure to the streaming current. In this communication, we investigate electrokinetic phenomena in undeveloped flows both numerically and experimentally. We confirm that the aforementioned sub-linearity occurs for nonporous as well as porous substrates. We also demonstrate that the channel heights estimated from the volume flow rate by using numerical simulations of undeveloped flows are in very good agreement with the reference values obtained from the electrical conductance (in contrast to the values estimated by using the conventional approach of Hagen-Poiseuille equation). The numerical fitting of channel-height dependences of streaming-current coefficient enables us to separate the contributions of external surface and porous sub-structure (in case of porous substrates) and obtain quite reasonable values of (effective) zeta-potentials in both cases. Nonetheless, the accuracy of experimental data deteriorates with increasing channel height, so it is generally advisable to vary the heights within a range below 100-150?m. PMID:24034221

Yaroshchuk, Andriy; Bernal, Edxon Eduardo Licón; Luxbacher, Thomas

2013-08-26

29

Herbicidal effects of soil-incorporated wheat.  

PubMed

The hydroxamic acid 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and the benzoxazolinones benzoxazolin-2-one (BOA) and 6-methoxybenzoxazolin-2-one (MBOA) have been identified as important allelochemicals in wheat. This study examines the possibility of exploiting the allelopathic properties of wheat as a weed control strategy by cultivating wheat as a precrop and incorporating plant residues into the soil before the next crop is sown. Different wheat varieties were cultivated in field plots during two seasons in both conventional and organic farming systems. Plants were sampled at various growth stages, and their contents of DIMBOA, MBOA, and BOA were determined by chemical analyses. The wheat samples were incorporated into soil, and the effect on germination and growth of 12 different weed species was examined in pot experiments under controlled conditions. In some cases significant effects were obtained, but the results were inconsistent and the effects were not correlated to the content of DIMBOA, MBOA, and BOA in the incorporated wheat plants. ED50 doses of the pure compounds were estimated in dose-response experiments in Petri dishes, and these turned out to be much higher than the predicted maximum concentrations of DIMBOA, MBOA, and BOA in the soil water following incorporation. The study shows that a prerequisite for exploiting the incorporation of wheat residues as a weed control strategy is the development of wheat varieties with an increased content of allelochemicals. PMID:16478217

Mathiassen, Solvejg K; Kudsk, Per; Mogensen, Betty B

2006-02-22

30

Effect of H2SO4 and HCl in the anode purging solution for the electrokinetic-Fenton remediation of soil contaminated with phenanthrene  

Microsoft Academic Search

The Electrokinetic-Fenton (EK-Fenton) process is a powerful technology to remediate organic-contaminated soil. The behavior of salts and acids introduced for the pH control has significant influence on the H2O2 stabilization and destruction of organic contaminants. In this study, the effects of the type and concentration of acids, which were introduced at the anode, were investigated for the treatment of clayey

Jung-Hwan Kim; Jong Yun Kim; Soo-Sam Kim

2009-01-01

31

Multi-frequency Electrokinetic Micromixing  

NASA Astrophysics Data System (ADS)

We report an electrokinetic process to rapidly mix micro and nanoliter volume solutions for microfluidics applications. The method consists in initiating a flow instability that will rapidly stir the microflow streams. The effect occurs by applying multi-frequency alternative current signals in a periodic array of planar microelectrodes. The device was manufactured using bulk titanium microfabrication. It consists of an array of 24 electrodes sitting on the bottom of 200 microns wide, 30 microns deep and 6 millimeters long titanium channel. The electrodes are 20 to 40 microns wide with a pitch of 40 to 80 microns depending on the configuration studied. The device is very versatile and can be used for micro-nano particles concentration, cells sorting and micromixing depending on the input signal applied. In the present study we present some measurements of the mixing behavior. We discuss the advantage of the multi-frequency electrokinetic micromixing and show some quantitative results.

Bottausci, Frederic; Mezic, Igor

2006-11-01

32

AC electrokinetic phenomena generated by microelectrode structures.  

PubMed

The field of AC electrokinetics is rapidly growing due to its ability to perform dynamic fluid and particle manipulation on the micro- and nano-scale, which is essential for Lab-on-a-Chip applications. AC electrokinetic phenomena use electric fields to generate forces that act on fluids or suspended particles (including those made of dielectric or biological material) and cause them to move in astonishing ways. Within a single channel, AC electrokinetics can accomplish many essential on-chip operations such as active micro-mixing, particle separation, particle positioning and micro-pattering. A single device may accomplish several of those operations by simply adjusting operating parameters such as frequency or amplitude of the applied voltage. Suitable electric fields can be readily created by micro-electrodes integrated into microchannels. It is clear from the tremendous growth in this field that AC electrokinetics will likely have a profound effect on healthcare diagnostics, environmental monitoring and homeland security. In general, there are three AC Electrokinetic phenomena (AC electroosmosis, dielectrophoresis and AC electrothermal effect) each with unique dependencies on the operating parameters. A change in these operating parameters can cause one phenomena to become dominant over another, thus changing the particle or fluid behavior. It is difficult to predict the behavior of particles and fluids due to the complicated physics that underlie AC electrokinetics. It is the goal of this publication to explain the physics and elucidate particle and fluid behavior. Our analysis also covers how to fabricate the electrode structures that generate them, and how to interpret a wide number of experimental observations using several popular device designs. This video article will help scientists and engineers understand these phenomena and may encourage them to start using AC Electrokinetics in their research. PMID:19066515

Hart, Robert; Oh, Jonghyun; Capurro, Jorge; Noh, Hongseok Moses

2008-07-28

33

Effect of a low-conductivity zone on field-amplified sample stacking in microchip micellar electrokinetic chromatography.  

PubMed

The effects of a low-conductivity (low-C) zone of an on-line sample preconcentration based on field-amplified sample stacking (FASS) under an acidic condition was investigated in microchip micellar electrokinetic chromatography (MCMEKC). By employing originally fabricated microchips with T- and cross-channel injectors on a single device, partial injection of the low-C zone and large-volume injection of a sample solution were demonstrated. As a typical result, the observed peak intensities of the fluorescent dyes were 1.5 - 2.0-fold enhanced by partial injection of the low-conductivity zone, as compared to those in FASS-MCMEKC without injecting the low-C zone; also, 30 - 40-fold enhancements of the detectability were achieved as compared to the conventional MCMEKC analyses. The resolutions of the hydrophobic analytes were also improved by introducing the low-C zone. The difference in the retention factors of model analytes in the high-C background and low-C zones was also estimated in order to clarify the effect of the low-C zone on the resolution and detectability in FASS-MCMEKC. PMID:23303098

Sueyoshi, Kenji; Kitagawa, Fumihiko; Otsuka, Koji

2013-01-01

34

Electrokinetic lift  

NASA Astrophysics Data System (ADS)

Electrolyte flow relative to a charged surface induces a bulk electric field (the ``streaming potential'' phenomena). This field, and the flow perturbation it animates, generate both electrical and hydrodynamic ``electro-viscous'' forces whose magnitude has been a matter of ongoing controversy. Recently we have revisited this problem, predicting O(2?) scaling (as opposed to earlier prediction of 4? and 6?), ?1 being the dimensionless Debye width. These electro-viscous forces can explain the anomalous repulsion of polystyrene microspheres from an adjacent wall in the presence of an imposed shear flow, observed by Prieve and co-workers. Owing to the symmetry properties of the linear Stokes equations, such repulsion is inadmissible in the absence of inertial effects. This particle--wall interaction is analyzed using our revised scheme. The undisturbed flow consists of three components: the `driving' shear mechanism and the `induced' particle translation and rotation. We consider a small dimensionless particle--wall gap ?. At leading-order, both the lift and additional drag are contributed by the inner gap region. The lift force is O(2?&-3circ;) while the additional drag is O(2?&-2circ;). The streaming-potential mechanism underlying these forces arises from the `induced' rather than the driving component.

Schnitzer, Ory; Yariv, Ehud; Frankel, Itzchak

2011-11-01

35

Effects of heavy metals on the electrokinetic properties of bacteria, yeast, and clay minerals  

SciTech Connect

The electrokinetic patterns of four bacteria (Bacillus subtilis, Bacillus megaterium, Pseudomonas aeruginosa, Agrobacterium radiobacter), two yeasts (Saccharomyces cerevisiae, Canida albicans), and two clay minerals (montmorillonite, kaolinite) in the presence of the chloride salts of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) and of Na and Mg were determined by microelectrophoresis. The cells and clays were net negatively charged at pH values above their isoelectric point (pI) in solutions of Na, Mg, Hg, and Pb with an ionic strength (..mu..) of 3 x 10/sup -4/. However, at pH values above pH 5.0, the charge of some bacteria, S. cerevisiae, and kaolinite changed to a net positive charge (charge reversal) in the presence of Cd, Cr, Cu, Ni, and Zn. The charge of the bacteria and S. cerevisiae also reversed in solution of Ni and Cu with a ..mu.. > 3 x 10/sup -4/, whereas there was no reversal in solutions with a ..mu.. < 3 x 10/sup -4/. The clays became net positively charged when the ..mu.. of Cu was > 3 x 10/sup -4/ and that of Ni was > 1.5 x 10/sup -4/. The charge of the cells and clays also reversed in solutions containing both Mg and Ni or both Cu and Ni (except montmorillonite) but not in solutions containing both Mg and Cu (except kaolinite) (..mu.. = 3 x 10/sup -4/). The pI of the cells in the presence of some heavy metals, especially Ni and Cr, was at higher pH values than in the presence of Na and Mg.

Collins, Y.E.

1987-01-01

36

[Effectiveness of incorporating a quality management system].  

PubMed

In 2003, the ISO 15189 international standardization program on the quality and competence of the clinical reference laboratory was introduced. To date, 46 facilities have committed themselves to providing a higher level of medical service by incorporating a quality management system (QMS) and acquiring accreditation. QMS is defined as "setting up a policy and goals pertaining to quality, and adopting an appropriate system," and is a scheme that includes all managerial and technical factors that can affect test results. Regarding the Health Sciences Research Institute Group, 4 facilities have previously received the accreditation described above, but in the process of implementing the QMS, a number of problems have been identified. Here, we report on the effectiveness of adopting such a QMS based on the results of employee questionnaires, internal audits, customer complaint analyses, and external audits by the Japan Accreditation Board for Conformity Assessment (JAB), the official inspection body for accreditation. PMID:20169949

Seki, Akira; Hankins, Raleigh W; Miya, Tetsumasa

2010-01-01

37

Effects of electrokinetic operation mode on removal of polycyclic aromatic hydrocarbons (PAHs), and the indigenous fungal community in PAH-contaminated soil.  

PubMed

Electrokinetic remediation is an emerging physical remediation technology for the removal of heavy metals and organic chemicals from contaminated soil. We set up a soil chamber (24 × 12 × 8 cm) with two stainless steel electrodes (12 × 0.5 cm), and a constant voltage gradient of 1.0 v cm(-1) or 2.0 v cm(-1) was applied to study the effects of unidirectional and altered directional electric field operation modes on the moisture content and pH, the removal rate of PAHs, and the abundance and diversity of indigenous fungi in a PAH-contaminated soil at the Benxi Iron and Steel Group Corporation (N41°17'24.4?, E123°43'05.8?), Liaoning Province, Northeast China. Electrokinetic remediation increased the PAH removal rate, but had less effect on soil moisture content and pH, in comparison with the control. In the 1 v cm(-1) altered directional operation, in particular, the PAH removal rate by the end of the experiment (on day 23) had increased from 5.2% of the control to 13.84% and 13.69% at distances of 4 and 20 cm from the anode, respectively, and to 18.97% in the middle region of the soil chamber. On day 23, the indigenous fungal 18S rRNA gene copy numbers and community diversity were significantly higher in a voltage gradient of 1 v cm(-1) than in a voltage gradient 2 v cm(-1). An altered directional operation was more conducive to the fungal community's uniform distribution than was a unidirectional operation of the electric field. We found the major PAH-degrading fungi Fusarium oxysporum and Rhizophlyctis rosea to be present under EK remediation. We suggest that a 1 v cm(-1) altered directional operation could be an appropriate electrokinetic operation mode for PAH removal, and the maintenance of abundance and diversity of the indigenous fungal community. PMID:23947706

Wang, Jian; Li, Fengmei; Li, Xu; Wang, Xiujuan; Li, Xinyu; Su, Zhencheng; Zhang, Huiwen; Guo, Shuhai

2013-01-01

38

Gradient elution for micellar electrokinetic capillary chromatography  

Microsoft Academic Search

A method for performing gradient elution in micellar electrokinetic capillary chromatography is developed. The influence of temperature and mobile phase organic solvent concentration on capacity factors is presented and attributed to changes in phase ratio and solute distribution coefficient. Solvent programming is more effective than temperature programming at adjusting retention due to its greater influence on distribution coefficient. As anticipated,

Anthony T. Balchunas; Michael J. Sepaniak

1988-01-01

39

Electrokinetic extraction of chromate from unsaturated soils  

Microsoft Academic Search

Heavy-metal contamination of soil and groundwater is a widespread problem in industrial nations. Remediation by excavation of such sites may not be cost effective or politically acceptable. Electrokinetic remediation is one possible remediation technique for in situ removal of such contaminants from unsaturated soils. Previous papers discussing the work performed by researchers at Sandia National Laboratories (SNL) and Sat-Unsat, Inc.

E. D. Mattson; E. R. Lindgren

1993-01-01

40

Effect of pH control at the anode for the electrokinetic removal of phenanthrene from kaolin soil  

Microsoft Academic Search

Polycyclic aromatic hydrocarbon (PAH)-contaminated soils exist at numerous sites, and these sites may threaten public health and the environment because many PAH compounds are toxic, mutagenic, and\\/or carcinogenic. PAHs are also hydrophobic and persistent, so conventional remediation methods are often costly or inefficient, especially when the contaminants are present in low permeability and\\/or organic soils. An innovative technique, electrokinetically enhanced

Richard E Saichek; Krishna R Reddy

2003-01-01

41

Electrokinetic mixing in microfluidic systems  

Microsoft Academic Search

The applications of electrokinetics in the development of microfluidic devices have been widely attractive in the past decade. Electrokinetic devices generally\\u000a require no external mechanical moving parts and can be made portable by replacing the power supply by small battery. Therefore,\\u000a electrokinetic-based microfluidic systems can serve as a viable tool in creating a lab-on-a-chip (LOC) or micro-total analysis\\u000a system (?TAS)

Chih-Chang Chang; Ruey-Jen Yang

2007-01-01

42

Electrokinetic Properties of Perlite  

Microsoft Academic Search

Electrokinetic properties of expanded and unexpanded perlite samples have been investigated using the microelectrophoresis technique. Perlite samples yield practically no isoelectric point in the pH range of 3 to 11. Both of the perlite samples remain negatively charged in the pH range studied. The expanded perlite has a more negatively charged surface than unexpanded perlite. NaCl, KNO3, NaNO3, Na2CO3, and

Mehmet D?g; Mahir Alkan; Ümit Çakir

1997-01-01

43

Electrokinetics on superhydrophobic surfaces  

NASA Astrophysics Data System (ADS)

On a superhydrophobic surface a liquid is exposed to a large air-water interface. The reduced wall friction is expected to cause a higher electro-osmotic mobility. On the other hand, the low charge density of a superhydrophobic surface reduces the electro-osmotic mobility. Due to a lack of experimental data it has not been clear so far whether the reduced wall friction or the reduced charge density dominate the electrokinetic mobilities. To separate the relative contributions of electrophoresis and electro-osmosis, the mobilities of colloids on a negatively charged hydrophilic, a superhydrophobic (Cassie) and a partially hydrophilized superhydrophobic (Cassie composite) coating were measured. To vary the charge density as well as its sign with respect to those of the colloids the partially hydrophilized surfaces were coated with polyelectrolytes. We analyzed the electrokinetic mobilities of negatively charged polystyrene colloids dispersed in aqueous medium on porous hydrophilic and superhydrophobic surfaces by confocal laser scanning electron microscopy. In all cases, the external electric field was parallel to the surface. The total electrokinetic mobilities on the superhydrophobic (Cassie) and negatively charged partially hydrophilized (Cassie composite) surfaces were similar, showing that electro-osmosis is small compared to electrophoresis. The positively charged Cassie composite surfaces tend to ‘trap’ the colloids due to attracting electrostatic interactions and rough morphology, reducing the mobility. Thus, either the charge density of the coatings in the Cassie composite state or its slip length is too low to enhance electro-osmosis.

Papadopoulos, Periklis; Deng, Xu; Vollmer, Doris; Butt, Hans-Jürgen

2012-11-01

44

Electrokinetics on superhydrophobic surfaces.  

PubMed

On a superhydrophobic surface a liquid is exposed to a large air-water interface. The reduced wall friction is expected to cause a higher electro-osmotic mobility. On the other hand, the low charge density of a superhydrophobic surface reduces the electro-osmotic mobility. Due to a lack of experimental data it has not been clear so far whether the reduced wall friction or the reduced charge density dominate the electrokinetic mobilities. To separate the relative contributions of electrophoresis and electro-osmosis, the mobilities of colloids on a negatively charged hydrophilic, a superhydrophobic (Cassie) and a partially hydrophilized superhydrophobic (Cassie composite) coating were measured. To vary the charge density as well as its sign with respect to those of the colloids the partially hydrophilized surfaces were coated with polyelectrolytes. We analyzed the electrokinetic mobilities of negatively charged polystyrene colloids dispersed in aqueous medium on porous hydrophilic and superhydrophobic surfaces by confocal laser scanning electron microscopy. In all cases, the external electric field was parallel to the surface. The total electrokinetic mobilities on the superhydrophobic (Cassie) and negatively charged partially hydrophilized (Cassie composite) surfaces were similar, showing that electro-osmosis is small compared to electrophoresis. The positively charged Cassie composite surfaces tend to 'trap' the colloids due to attracting electrostatic interactions and rough morphology, reducing the mobility. Thus, either the charge density of the coatings in the Cassie composite state or its slip length is too low to enhance electro-osmosis. PMID:23113983

Papadopoulos, Periklis; Deng, Xu; Vollmer, Doris; Butt, Hans-Jürgen

2012-10-31

45

Incorporating Carer Effects into Economic Evaluation  

Microsoft Academic Search

Background: Despite great interest in the development of methods used in the economic evaluation of health technologies, the effects of carer costs and quality of life (QOL) on the cost effectiveness of treatments has not been widely explored. Yet carer effects are clearly evident in the literature and relevant to the perspective of many published economic evaluations. Objective: To examine

Simon Dixon; Mel Walker; Sam Salek

2006-01-01

46

ELECTROKINETICS, INC. INSITU BIO REMEDIATION BY ELECTROKINETIC INJECTION EMERGING TECHNOLOGY SUMMARY  

EPA Science Inventory

Electrokinetics, Inc. through a cooperative agreement with USEPA's NRMRL conducted a laboratory evaluation of electrokinetic transport as a means to enhance in-situ bioremediation of trichloroethene (TCE). Four critical aspects of enhancing bioremediation by electrokinetic inject...

47

Effect of surfactant counterion and organic modifier on the properties of surfactant vesicles in electrokinetic chromatography.  

PubMed

Counterion and organic modifier are two parameters in EKC that can be varied in order to obtain improved solubility, selectivity, and efficiency. The effect of changing surfactant counterion and/or organic modifier on the chromatographic and electrophoretic properties of cetyltrimethylammonium bromide (CTAB)/sodium octyl sulfate (SOS) vesicles is examined in EKC. The vesicles are prepared in a 1:3.66 cationic/ anionic mole ratio for a total surfactant concentration of 69 mM. The cationic CTAB is replaced by cetyltrimethylammonium chloride (CTAC) and the first use of CTAC/SOS vesicles is reported. The mean diameter of the CTAC/SOS vesicles is 96 nm while that of the CTAB/SOS vesicles is 85 nm. A class I modifier (2-amino-1-butanol) and a class II modifier (acetonitrile) have similar effects on the EOF, elution range, methylene selectivity, and the efficiency of the CTAB/SOS vesicles and the CTAC/SOS vesicles. Upon addition of 10% ACN, there is roughly a 10-fold increase in the efficiency of heptanophenone, a model hydrophobic compound, compared to the efficiency using unmodified vesicles. Linear free energy relationship (LFER) analysis using the Abraham solvation model is employed to characterize solute-vesicle interactions. The results suggest that organic modifier-vesicle interactions depend somewhat on the counterion. PMID:16138692

Schuster, Stephanie A; Foley, Joe P

2005-08-01

48

Incorporating Allee effects into reintroduction strategies  

Microsoft Academic Search

Allee effects, the reduction of vital rates at low population densities, can occur through several mechanisms, all of which\\u000a potentially apply to reintroduced populations. Reintroduced populations are initially at low densities, hence Allee effects\\u000a can potentially lead to reintroduction failure despite habitat quality being sufficient to allow long-term persistence if\\u000a the population survived the establishment phase. The probability of such

Doug P. Armstrong; Heiko U. Wittmer

49

Sweeping as a multistep enrichment process in micellar electrokinetic chromatography: the retention factor gradient effect.  

PubMed

The application of a new method developed for the assessment of sweeping efficiency in MEKC under homogeneous and inhomogeneous electric field conditions is extended to the general case, in which the distribution coefficient and the electric conductivity of the analyte in the sample zone and in the separation compartment are varied. As test analytes p-hydroxybenzoates (parabens), benzamide and some aromatic amines are studied under MEKC conditions with SDS as anionic surfactant. We show that in the general case - in contrast to the classical description - the obtainable enrichment factor is not only dependent on the retention factor of the analyte in the sample zone but also dependent on the retention factor in the background electrolyte (BGE). It is shown that in the general case sweeping is inherently a multistep focusing process. We describe an additional focusing/defocusing step (the retention factor gradient effect, RFGE) quantitatively by extending the classical equation employed for the description of the sweeping process with an additional focusing/defocusing factor. The validity of this equation is demonstrated experimentally (and theoretically) under variation of the organic solvent content (in the sample and/or the BGE), the type of organic solvent (in the sample and/or the BGE), the electric conductivity (in the sample), the pH (in the sample), and the concentration of surfactant (in the BGE). It is shown that very high enrichment factors can be obtained, if the pH in the sample zone makes possible to convert the analyte into a charged species that has a high distribution coefficient with respect to an oppositely charged micellar phase, while the pH in the BGE enables separation of the neutral species under moderate retention factor conditions. PMID:23726349

El-Awady, Mohamed; Pyell, Ute

2013-05-02

50

Enhancing Clinical Trials by Incorporating Side Effects  

ERIC Educational Resources Information Center

Evidence-based medicine is often seen as a model for evidence-based education, and deservedly so, but evaluators in education have been slow to adopt one of its salient features, attention to side effects. Many education evaluations focus almost exclusively on efficacy, that is on achievement test scores. Regardless of domain, all interventions…

Schrag, Francis

2009-01-01

51

Separation of estrogens by micellar electrokinetic chromatography  

Microsoft Academic Search

Capillary electrophoresis of the sex hormone estrogens using different buffer components was investigated. Free zone electrophoresis with 10 mM phosphate buffer (pH 11.5) or 10 mM phosphate buffer with 10–20% methanol was not effective in separating the ten estrogens used in this study. However, nine estrogens were resolved by micellar electrokinetic chromatography using a 10 mM borate buffer (pH 9.2)

King C. Chan; Gary M. Muschik; Haleem J. Issaq; Pentti K. Siiteri

1995-01-01

52

Electrokinetic chromatography without electroosmotic flow.  

PubMed

This review summarizes the various aspects of conducting electrokinetic chromatography in coated columns with suppressed electroosmotic flow. The specific features of the technique will be presented and the potential applications explored. The equations of migration, resolution and zone spreading for neutral solutes will be presented, compared, and contrasted with those of conventional electrokinetic chromatography in bare-silica columns. The principle of separation is the same in electrokinetic chromatography with or without electroosmotic flow; however, there are many significant differences that will be highlighted. PMID:9463907

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

1997-12-19

53

Competition between Dukhin's and Rubinstein's electrokinetic modes  

NASA Astrophysics Data System (ADS)

The combined effect of two modes of electroconvection, i.e., (a) the electro-osmotic flow of the second kind induced by a curved membrane surface and (b) electrokinetic instability, is studied numerically. Both physical mechanisms are responsible for electric current enhancement to the surface, and these modes are strongly nonlinearly coupled. For the limiting regimes, their resonant interaction near the threshold of instability with a corresponding resonantly amplified current enhancement is found. For the overlimiting regimes, inside the unstable region, their interaction becomes more complex with negative “sideband” and positive “subharmonic” resonant interactions. Wall corrugation can still be in resonance with the unstable modes. At some wave numbers of corrugation, these two mechanisms compete and electrokinetic instability can even be completely suppressed by the wall corrugation.

Chang, H.-C.; Demekhin, E. A.; Shelistov, V. S.

2012-10-01

54

Marble protection: An inorganic electrokinetic approach  

NASA Astrophysics Data System (ADS)

The influence of an electric potential difference in an aqueous solution was studied as a method for depositing a calcium oxalate coating over a weathered carbonatic stone. Samples of weathered Carrara white marble were treated at 15 and 50 °C for 5 h in an electrokinetic cell, specifically conceived for this study, containing a solution of ammonium oxalate (4% by weight), and were subsequently characterised by scanning electron microscopy, X-ray diffractometry, thermogravimetric analysis and mercury intrusion porosimetry. The electrokinetic treatment proved to be a cost effective and time saving process, able to produce a thick and homogeneous calcium oxalate coating over the stone surface that improves its chemical and physical resistance in low pH environments, and is able to protect the stone from the by-products of urban pollution.

Meloni, Paola; Manca, Francesco; Carcangiu, Gianfranco

2013-05-01

55

Band-broadening suppressed effect in long turned geometry channel and high-sensitive analysis of DNA sample by using floating electrokinetic supercharging on a microchip.  

PubMed

A featured microchip owning three big reservoirs and long turned geometry channel was designed to improve the detection limit of DNA fragments by using floating electrokinetic supercharging (FEKS) method. The novel design matches the FEKS preconcentration needs of a large sample volume introduction with electrokinetic injection (EKI), as well as long duration of isotachophoresis (ITP) process to enrich low concentration sample. In the curved channel [ approximately 45.6 mm long between port 1 (P1) and the intersection point of two channels], EKI and ITP were performed while the side port 3 (P3) was electrically floated. The turn-induced band broadening with or without ITP process was investigated by a computer simulation (using CFD-ACE+ software) when the analytes traveling through the U-shaped geometry. It was found that the channel curvature determined the extent of band broadening, however, which could be effectively eliminated by the way of ITP. After the ITP-stacked zones passed the intersection point from P1, they were rapidly destacked for separation and detection from ITP to zone electrophoresis by using leading ions from P3. The FEKS carried on the novel chip successfully contributed to higher sensitivities of DNA fragments in comparison with our previous results realized on either a single channel or a cross microchip. The analysis of low concentration 50 bp DNA step ladders (0.23 mugml after 1500-fold diluted) was achieved with normal UV detection at 260 nm. The obtained limit of detections (LODs) were on average 100 times better than using conventional pinched injection, down to several ngml for individual DNA fragment. PMID:20644677

Xu, Zhongqi; Murata, Kenji; Arai, Akihiro; Hirokawa, Takeshi

2010-03-12

56

Enhanced on-chip SERS based biomolecular detection using electrokinetically active microwells  

Microsoft Academic Search

Here we present a novel microfluidic technique for on-chip surface enhanced Raman spectroscopy (SERS) based biomolecular detection, exploiting the use of electrokinetically active microwells. Briefly, the chip comprises of a series of microfluidic channels containing embedded microwells that, when electrically actuated, either locally attract or repulse species from solution through a combination of electrokinetic effects. We demonstrate that the approach

Yun Suk Huh; Aram J. Chung; Bernardo Cordovez; David Erickson

2009-01-01

57

Electrokinetic transport in microchannels with random roughness  

SciTech Connect

We present a numerical framework to model the electrokinetic transport in microchannels with random roughness. The three-dimensional microstructure of the rough channel is generated by a random generation-growth method with three statistical parameters to control the number density, the total volume fraction, and the anisotropy characteristics of roughness elements. The governing equations for the electrokinetic transport are solved by a high-efficiency lattice Poisson?Boltzmann method in complex geometries. The effects from the geometric characteristics of roughness on the electrokinetic transport in microchannels are therefore modeled and analyzed. For a given total roughness volume fraction, a higher number density leads to a lower fluctuation because of the random factors. The electroosmotic flow rate increases with the roughness number density nearly logarithmically for a given volume fraction of roughness but decreases with the volume fraction for a given roughness number density. When both the volume fraction and the number density of roughness are given, the electroosmotic flow rate is enhanced by the increase of the characteristic length along the external electric field direction but is reduced by that in the direction across the channel. For a given microstructure of the rough microchannel, the electroosmotic flow rate decreases with the Debye length. It is found that the shape resistance of roughness is responsible for the flow rate reduction in the rough channel compared to the smooth channel even for very thin double layers, and hence plays an important role in microchannel electroosmotic flows.

Wang, Moran [Los Alamos National Laboratory; Kang, Qinjun [Los Alamos National Laboratory

2008-01-01

58

Simulation of electrokinetic flow in microfluidic channels  

NASA Astrophysics Data System (ADS)

Electrokinetic phenomena become an increasingly efficient fluid transport mechanism in micro- and nano-fluidic fields. These phenomena have also been applied successfully in microfluidic devices to achieve particle separation, pre-concentration and mixing. Electrokinetic is the flow produced by the action of an electric field on a fluid with a net charge, where the charged ions of fluid are able to drag the whole solution through the channels in the microfluidic device from one analyzing point to the other. We will present the simulation results of electrokinetic transports of fluid in various typical micro-channel geometries such as T-channel, Y-channel, cross channel and straight channel. In practice, high-speed micro-PIV technique is used to measure transient fluidic phenomena in a microfluidic channel. Particle Image Velocimetry (PIV) systems provide two- or three-dimensional velocity maps in flows using whole field techniques based on imaging the light scattered by small particles in the flow illuminated by a laser light sheet. The system generally consists of an epifluorescent microscope, CW laser and a high-speed CMOS of CCD camera. The flow of a liquid, (water for example), containing fluorescent particle is then analyzed in a counter microchannel by the highly accurate PIV method. One can then compare the simulated and experimental microfluidic flow due to electroosmotic effect.

Sabur, Romena; Matin, M.

2005-08-01

59

Electrokinetic potential of flotation pulps  

SciTech Connect

Studies have been done on the possibility of intensifying flotation processes by electrical treatment of flotation pulps. The electrokinetic potential is a parameter which may characterize the flotation properties of pulps. In this paper, the authors obtain calculation relationships for determining the electrokinetic potential from the results of measuring sedimentation potential. The equations obtained are used to study both sedimentationally stable pulps and sedimentationally unstable coarsely dispersed suspensions.

Mis'nik, V.A.

1988-03-01

60

dc electrokinetic transport of cylindrical cells in straight microchannels  

PubMed Central

Electrokinetic transport of cylindrical cells under dc electric fields in a straight microfluidic channel is experimentally and numerically investigated with emphasis on the dielectrophoretic (DEP) effect on their orientation variations. A two-dimensional multiphysics model, composed of the Navier–Stokes equations for the fluid flow and the Laplace equation for the electric potential defined in an arbitrary Lagrangian–Eulerian framework, is employed to capture the transient electrokinetic motion of cylindrical cells. The numerical predictions of the particle transport are in quantitative agreement with the obtained experimental results, suggesting that the DEP effect should be taken into account to study the electrokinetic transport of cylindrical particles even in a straight microchannel with uniform cross-sectional area. A comprehensive parametric study indicates that cylindrical particles would experience an oscillatory motion under low electric fields. However, they are aligned with their longest axis parallel to the imposed electric field under high electric fields due to the induced DEP effect.

Ai, Ye; Beskok, Ali; Gauthier, David T.; Joo, Sang W.; Qian, Shizhi

2009-01-01

61

ELECTROKINETIC REMEDIATION: BASICS AND TECHNOLOGY STATUS  

EPA Science Inventory

Electrokinetic remediation, variably named as electrochemical soil processing, electromigration, electrokinetic decontamination or electroreclamation uses electric currents to extract radionuclides, heavy metals, certain organic compounds, or mixed inorganic species and some orga...

62

EMERGING TECHNOLOGY BULLETIN: ELECTROKINETIC SOIL PROCESSING  

EPA Science Inventory

Electrokinetic Soil Processing (or Electrokinetic Remediation) uses two series of electrodes (anodes and cathodes) positioned inside compartments that allow egress and ingress of pore fluids to the porous media. The compartments are filled with water or other process fluids and ...

63

Electrokinetic remediation of metal contaminated glacial tills  

Microsoft Academic Search

This paper presents the results of an experimental investigation which studied the feasibility of using the electrokinetic process to remediate contaminated clays of glacial origin, otherwise known as glacial tills. An overview of the electrokinetic phenomena, as well as previously performed laboratory and field investigations, is first presented. The methodology of the electrokinetic experiments which were conducted to investigate the

K. R. Reddy; A. B. Shirani

1997-01-01

64

Laboratory Experiment on Electrokinetic Remediation of Soil  

ERIC Educational Resources Information Center

|Electrokinetic remediation is a method of decontaminating soil containing heavy metals and polar organic contaminants by passing a direct current through the soil. An undergraduate chemistry laboratory is described to demonstrate electrokinetic remediation of soil contaminated with copper. A 30 cm electrokinetic cell with an applied voltage of 30…

Elsayed-Ali, Alya H.; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E.

2011-01-01

65

Separation and determination of the effective components in the alabastrum of Edgeworthia chrysantha Lindl. by micellar electrokinetic capillary chromatography.  

PubMed

A rapid and efficient micellar electrokinetic capillary chromatography (MEKC) method was developed to analyze edgeworoside C (1), kaempferol-3-O-beta-D-glucoside (2) and rutin (3) in the alabastrum of Edgeworthia chrysantha Lindl. for the first time. The factors that affect the separation were studied, such as the concentrations of the buffer, SDS, and organic modifier, the apparent pH, the applied voltage and temperature. The analytes were well separated within 15 min with an electrolyte containing 25 mM Na(2)B(4)O(7), 30 mM NaH(2)PO(4), 60mM SDS and 15% acetonitrile (pH(*) 9.1) at 25 kV and 15 degrees C. The correlation coefficients between the peak areas of analytes and the corresponding concentrations were 0.9976-0.9981 under the optimum conditions. The relative standard deviations (R.S.D.) of the migration time and peak area were in the range 0.6-1.7 and 1.9-5.3%, respectively. The contents of analytes in E. chrysantha Lindl. collected from the different places were successfully determined with the recoveries ranging from 95.9 to 104.3%. And, the results demonstrated that there was significant difference between the two real samples. PMID:16269220

Wang, Shufang; Cheng, Yiyu

2005-11-02

66

Effect of active packaging incorporated with triclosan on bacteria adhesion.  

PubMed

Antimicrobial polyethylene and cellulose based films incorporated with triclosan were studied. The antimicrobial efficacy, the hydrophobicity, microscopic and the mechanical characteristics of the films, as well free energy of adhesion between bacteria and antimicrobial films were evaluated. It was observed that both polyethylene and cellulose based films incorporated with the antimicrobial were homogeneous. Furthermore, the addition of triclosan did not affect mechanical characteristics of the films (P?> 0.05). However, triclosan incorporated into polyethylene films reduced its hydrophobicity while antimicrobial cellulose based films became more hydrophobic. The adhesion was thermodynamically favorable between tested bacteria and polyethylene films. On the other hand, the adhesion to triclosan cellulose based film was thermodynamically unfavorable to Staphylococcus aureus and Escherichia coli and favorable to Listeria innocua and Pseudomonas aeruginosa. Polyethylene and cellulose based films showed inhibitory effect against S. aureus and E. coli, being the inhibition halo higher for polyethylene films. This study improves the knowledge about antimicrobial films. PMID:21535496

Camilloto, Geany P; Pires, Ana Clarissa S; Soares, Nilda de Fátima F; Araújo, Emiliane A; Andrade, Nélio J; Ferreira, Sukarno O

2010-10-01

67

Physicochemical sensitivities of tropical peat to electrokinetic environment  

Microsoft Academic Search

Tropical peat is unconsolidated superficial deposits with high non-crystalline colloid (humus) content, constituting the subsurface of wetland systems. Laboratory experiments were carried out on a very slightly decomposed fibric and a highly decomposed amorphous, undisturbed tropical peat soils, to determine the physicochemical effects on the peats due to electrokinetic (EK) treatment in terms of mechanisms and resulting effects in the

Afshin Asadi; Bujang B. K. Huat; Mohamed M. Hanafi; Thamer A. Mohamed; Nader Shariatmadari

2010-01-01

68

A macroion electrokinetics algorithm.  

PubMed

A numerical algorithm is presented for the standard model of macroion electrokinetics and certain generalizations of it. The macroion consists of a cylindrical section with identical, hemispheroidal endcaps, each piece having arbitrary length. The system of one macroion and adjoining salt solution is subjected to an arbitrary sequence of pulsed electrical fields and pulsed translational and rotational velocities. Numerical solutions are obtained for the time dependent electrostatic and mobile ion concentration fields and the solvent velocity. From these fields the dielectric response, force, and torque are calculated. Generalizations of the standard model include the diffusive motion of macroion surface charges, partial slip of solvent motion at the macroion surface, and a simple model for the reactive exchange of surface charge with solution ions. The primary illustrative application is to recent measurements of electric birefringence versus applied field frequency for poly-(tetrafluorothylene) colloidal particles, but a few results are presented for the dielectric response of DNA fragments and of spherical colloidal particles. The source code and additional details are provided as supplementary documentation. PMID:16774422

Fixman, Marshall

2006-06-01

69

A macroion electrokinetics algorithm  

NASA Astrophysics Data System (ADS)

A numerical algorithm is presented for the standard model of macroion electrokinetics and certain generalizations of it. The macroion consists of a cylindrical section with identical, hemispheroidal endcaps, each piece having arbitrary length. The system of one macroion and adjoining salt solution is subjected to an arbitrary sequence of pulsed electrical fields and pulsed translational and rotational velocities. Numerical solutions are obtained for the time dependent electrostatic and mobile ion concentration fields and the solvent velocity. From these fields the dielectric response, force, and torque are calculated. Generalizations of the standard model include the diffusive motion of macroion surface charges, partial slip of solvent motion at the macroion surface, and a simple model for the reactive exchange of surface charge with solution ions. The primary illustrative application is to recent measurements of electric birefringence versus applied field frequency for poly-(tetrafluorothylene) colloidal particles, but a few results are presented for the dielectric response of DNA fragments and of spherical colloidal particles. The source code and additional details are provided as supplementary documentation.

Fixman, Marshall

2006-06-01

70

Pressure and electrokinetic injections for on-line sample stacking neutral analytes in microemulsion electrokinetic chromatography with salt-containing matrixes.  

PubMed

An on-line technique for pressure and electrokinetic injections of long sample plugs with simultaneous stacking of neutral analytes (notoginsenoside R(1), ginsenoside Rg(1), ginsenoside Rf, ginsenoside Rh(1), ginsenoside Rd, ginsenoside Rg3) in microemulsion electrokinetic chromatography is presented. The effects of salt concentration, sample plug length, organic modification of the sample matrix, oil phase and SDS concentration on stacking efficiency were examined in order to optimize the two injection methods. In microemulsion electrokinetic chromatography, the effect of the type of oil and SDS content on stacking mechanism is often sophisticated. This study had demonstrated that the oil type and SDS content in microemulsion indeed markedly altered the affinity of microemulsion with analytes. Finally, in comparison with the electrokinetic injection method, the most apparent disadvantages of the pressure injection method were the relatively high LOD and poor reproducibility. PMID:18942679

Cao, Jun; Qi, Lian-Wen; Chen, Jun; Li, Ping

2008-11-01

71

Effects of sodium hypochlorite and high pH buffer solution in electrokinetic soil treatment on soil chromium removal and the functional diversity of soil microbial community.  

PubMed

Effects of sodium hypochlorite (NaClO), applied as an oxidant in catholyte, and high pH buffer solution on soil Cr removal and the functional diversity of soil microbial community during enhanced electrokinetic treatments of a chromium (Cr) contaminated red soil are evaluated. Using pH control system to maintain high alkalinity of soil together with the use of NaClO increased the electrical conductivities of soil pore liquid and electroosmotic flux compared with the control (Exp-01). The pH control and NaClO improved the removal of Cr(VI) and total Cr from the soil. The highest removal percentages of soil Cr(VI) and total Cr were 96 and 72%, respectively, in Exp-04 when the pH value of the anolyte was controlled at 10 and NaClO was added in the catholyte. The alkaline soil environment and introduction of NaClO in the soil enhanced the desorption of Cr(VI) from the soil and promoted Cr(III) oxidation to mobile Cr(VI), respectively. However, the elevated pH and introduction of NaClO in the soil, which are necessary for improving the removal efficiency of soil Cr, resulted in a significantly adverse impact on the functional diversity of soil microbial community. It suggests that to assess the negative impact of extreme conditions for enhancing the extraction efficiencies of Cr on the soil properties and function is necessary. PMID:16956724

Cang, Long; Zhou, Dong-Mei; Alshawabkeh, Akram N; Chen, Hai-Feng

2006-08-03

72

Electrokinetic high pressure hydraulic system  

SciTech Connect

A compact high pressure hydraulic pump having no moving mechanical parts for converting electric potential to hydraulic force. The electrokinetic pump, which can generate hydraulic pressures greater than 2500 psi, can be employed to compress a fluid, either liquid or gas, and manipulate fluid flow. The pump is particularly useful for capillary-base systems. By combining the electrokinetic pump with a housing having chambers separated by a flexible member, fluid flow, including high pressure fluids, is controlled by the application of an electric potential, that can vary with time.

Paul, Phillip H. (Livermore, CA); Rakestraw, David J. (Fremont, CA)

2000-01-01

73

Gradient elution for micellar electrokinetic capillary chromatography  

SciTech Connect

A method for performing gradient elution in micellar electrokinetic capillary chromatography is developed. The influence of temperature and mobile phase organic solvent concentration on capacity factors is presented and attributed to changes in phase ratio and solute distribution coefficient. Solvent programming is more effective than temperature programming at adjusting retention due to its greater influence on distribution coefficient. As anticipated, phase ratio changes could not be exploited due to concomitant losses in column efficiency. A stepwise solvent gradient involving increasing concentrations of 2-propanol and Triton-X-100 is used for the separation of a test mixture of derivatized amines.

Balchunas, A.T.; Sepaniak, M.J.

1988-04-01

74

Colloid particle and protein deposition - electrokinetic studies.  

PubMed

Recent developments in the electrokinetic determination of particle, polyelectrolyte and protein deposition at solid/electrolyte interfaces, are reviewed. In the first section basic theoretical results are discussed enabling a quantitative interpretation of the streaming current/potential and microelectrophoretic measurements. Experimental results are presented, pertinent to electrokinetic characteristics of simple (homogeneous) surfaces such as mica, silica and various polymeric surfaces used in protein studies. The influence of the ionic strength, background electrolyte composition and pH is discussed, and the effective (electrokientic) charge of these interfaces is evaluated. In the next section, experimental data obtained by streaming potential measurements for colloid particle mono- and bilayers are presented and interpreted successfully in terms of available theoretical approaches. These results, obtained for model systems of monodisperse colloid particles are used as reference data for discussion of more complicated experiments performed for polyelectrolyte and protein covered surfaces. Results are discussed, obtained for cationic polyelectrolytes (PEI, PAH) and fibrinogen adsorbing on mica, interpreted quantitatively in terms of the theoretical approach postulating a heterogeneous 3D charge distribution. The Gouy-Chapman model, based on the continuous charge distribution proved inadequate. Interesting experimental data are also discussed, obtained by electrophoretic methods in the case of protein adsorption on colloid latex particles. In the last section, supplementary results on particle deposition on heterogeneous surfaces produced by controlled protein adsorption are discussed. Quantitative relationships between the amount of adsorbed protein, zeta potential of the interface and the particle coverage are specified. Possibility of evaluating the heterogeneity of protein charge distribution is pointed out. The anomalous deposition of colloid particles on protein molecules bearing the same sign of zeta potential, which contradicts classical DLVO theory, is interpreted in terms of the fluctuation theory. It is concluded that theoretical and experimental results obtained for model colloid systems and flat interfaces can be effectively used for interpretation of protein adsorption phenomena, studied by electrophoresis. In this way the universality of electrokinetic phenomena is underlined. PMID:21621181

Adamczyk, Z; Nattich, M; Wasilewska, M; Zaucha, M

2011-04-30

75

Electrokinetically pumped high pressure sprays  

DOEpatents

An electrokinetic pump capable of producing high pressure is combined with a nozzle having a submicron orifice to provide a high pressure spray device. Because of its small size, the device can be contained within medical devices such as an endoscope for delivering biological materials such as DNA, chemo therapeutic agents, or vaccines to tissues and cells.

Schoeniger, Joseph S. (Oakland, CA); Paul, Phillip H. (Livermore, CA); Schoeniger, Luke (Pittsford, NY)

2002-01-01

76

Electrokinetically pumped high pressure sprays  

DOEpatents

An electrokinetic pump capable of producing high pressure is combined with a nozzle having a submicron orifice to provide a high pressure spray device. Because of its small size, the device can be contained within medical devices such as an endoscope for delivering biological materials such as DNA, chemo therapeutic agents, or vaccines to tissues and cells.

Schoeniger, Joseph S. (Oakland, CA); Paul, Phillip H. (Livermore, CA); Schoeniger, Luke (Pittsford, NY)

2005-11-01

77

AC electrokinetics: applications for nanotechnology  

Microsoft Academic Search

The phenomena of dielectrophoresis and electrorotation, collectively referred to as AC electrokinetics, have been used for many years to study, manipulate and separate particles on the cellular (1 µm or more) scale. However, the technique has much to offer the expanding field of nanotechnology, that is the precise manipulation of particles on the nanometre scale. In this paper we present

Michael Pycraft Hughes

2000-01-01

78

Electrokinetic confinement of axonal growth for dynamically configurable neural networks.  

PubMed

Axons in the developing nervous system are directed via guidance cues, whose expression varies both spatially and temporally, to create functional neural circuits. Existing methods to create patterns of neural connectivity in vitro use only static geometries, and are unable to dynamically alter the guidance cues imparted on the cells. We introduce the use of AC electrokinetics to dynamically control axonal growth in cultured rat hippocampal neurons. We find that the application of modest voltages at frequencies on the order of 10(5) Hz can cause developing axons to be stopped adjacent to the electrodes while axons away from the electric fields exhibit uninhibited growth. By switching electrodes on or off, we can reversibly inhibit or permit axon passage across the electrodes. Our models suggest that dielectrophoresis is the causative AC electrokinetic effect. We make use of our dynamic control over axon elongation to create an axon-diode via an axon-lock system that consists of a pair of electrode 'gates' that either permit or prevent axons from passing through. Finally, we developed a neural circuit consisting of three populations of neurons, separated by three axon-locks to demonstrate the assembly of a functional, engineered neural network. Action potential recordings demonstrate that the AC electrokinetic effect does not harm axons, and Ca(2+) imaging demonstrated the unidirectional nature of the synaptic connections. AC electrokinetic confinement of axonal growth has potential for creating configurable, directional neural networks. PMID:23314575

Honegger, Thibault; Scott, Mark A; Yanik, Mehmet F; Voldman, Joel

2013-02-21

79

Analysis of electrokinetic sedimentation of dredged Welland River sediment.  

PubMed

The Welland River is a tributary of the Niagara River. In the late 1980s it was discovered that a section of the Welland River was contaminated with heavy metals as a results of two sewer outfalls that has been used by a steel plant and local industrial and municipal operations for the last 50-60 years. One of the major problems encountered in the treatment of the dredged Welland River sediment is a slow rate of sedimentation due to the large proportion of fine solids in the sediment. In this study, the results of electrokinetic sedimentation of the Welland River sediment are analyzed based on the principles of gravitational and electrokinetic sedimentation. It was found that the effects of electric field intensity and the initial solid concentration of the suspension are the dominating factors governing the average particle settling velocity, the coefficient of free settling in the free settling stage and the coefficient of sedimentation in the hindered settling stage. The electrokinetic treatment is proven to be effective in terms of increasing the free and hindered settling velocities, reducing the overall sedimentation time and increasing the final solid concentration of the sediment. Thus, electrokinetics can be used to accelerate sedimentation of dilute solid suspensions, such as dredged sediment, wastewater and mine tailings. PMID:11463505

Mohamedelhassan, E; Shang, J Q

2001-07-30

80

Hybrid electrokinetics for separation, mixing, and concentration of colloidal particles.  

PubMed

The advent of nanotechnology has facilitated the preparation of colloidal particles with adjustable sizes and the control of their size-dependent properties. Physical manipulation, such as separation, mixing, and concentration, of these colloidal particles represents an essential step for fully utilizing their potential in a wide spectrum of nanotechnology applications. In this study, we investigate hybrid electrokinetics, the combination of dielectrophoresis and electrohydrodynamics, for active manipulation of colloidal particles ranging from nanometers to micrometers in size. A concentric electrode configuration, which is optimized for generating electrohydrodynamic flow, has been designed to elucidate the effectiveness of hybrid electrokinetics and define the operating regimes for different microfluidic operations. The results indicate that the relative importance of electrohydrodynamics increases with decreasing particle size as predicted by a scaling analysis and that electrohydrodynamics is pivotal for manipulating nanoscale particles. Using the concentric electrodes, we demonstrate separation, mixing, and concentration of colloidal particles by adjusting the relative strengths of different electrokinetic phenomena. The effectiveness of hybrid electrokinetics indicates its potential to serve as a generic technique for active manipulation of colloidal particles in various nanotechnology applications. PMID:19420574

Sin, Mandy L Y; Shimabukuro, Yusuke; Wong, Pak Kin

2009-04-01

81

[Anolyte enhanced electrokinetic remediation of fluorine-contaminated soils].  

PubMed

An experimental study was carried out in order to determine the characteristics of migration and its influencing factor of soil fluorine in the electrokinetic process under different applied voltage and concentration of anolyte. The feasibility of anolyte enhanced on electrokinetic remediation of fluorine-contaminated soil was analyzed. The results show that when deionized water is used as anolyte with the 1.0 V/cm voltage gradient, the cumulative mass of fluorine in catholyte and anolyte are 8.2 mg and 47.7 mg respectively and the removal rate of fluorine is only 8.8%. Anolyte enhanced electrokinetic process can promote effectively the migration of fluoride in soil. When 0.02 mol/L NaOH solutionis employed as the anolyte, the removal rates are 25.9%, 31.2% and 47.3% with 1.0, 1.5 and 2.0 V/cm voltage gradient respectively. As the concentration of anolyte increased to 0.1 mol/L, the removal rates are 55.4%, 61.1% and 73.0%. The electromigration is the main transport mechanism and the electroosmotic flow has an effect on the migration of fluorine in soil. The voltage gradient and the concentration of anolyte are the main factors influencing the removal rate of fluorine in soil. Appropriate anolyte enhanced electrokinetic method can be applied to remediate fluorine from contaminated soil. PMID:19775012

Zhu, Shu-Fa; Yan, Chun-Li; Dong, Tie-You; Tang, Hong-Yan

2009-07-15

82

An AC electrokinetics facilitated biosensor cassette for rapid pathogen identification.  

PubMed

To develop a portable point-of-care system based on biosensors for common infectious diseases such as urinary tract infection, the sensing process needs to be implemented within an enclosed fluidic system. On chip sample preparation of clinical samples remains a significant obstacle to achieving robust sensor performance. Herein AC electrokinetics is applied in an electrochemical biosensor cassette to enhance molecular convection and hybridization efficiency through electrokinetics induced fluid motion and Joule heating induced temperature elevation. Using E. coli as an exemplary pathogen, we determined the optimal electrokinetic parameters for detecting bacterial 16S rRNA in the biosensor cassette based on the current output, signal-to-noise ratio, and limit of detection. In addition, a panel of six probe sets targeting common uropathogenic bacteria was demonstrated. The optimized parameters were also validated using patient-derived clinical urine samples. The effectiveness of electrokinetics for on chip sample preparation will facilitate the implementation of point-of-care diagnosis of urinary tract infection in the future. PMID:23626988

Ouyang, Mengxing; Mohan, Ruchika; Lu, Yi; Liu, Tingting; Mach, Kathleen E; Sin, Mandy L Y; McComb, Mason; Joshi, Janhvi; Gau, Vincent; Wong, Pak Kin; Liao, Joseph C

2013-07-01

83

Electrokinetics of Correlated Electrolytes and Ionic Liquids  

NASA Astrophysics Data System (ADS)

Perhaps the most basic assumption of classical electrokinetic theory is the mean-field approximation, where the each ion feels only the electric field produced by the mean charge density (via Poisson's equation) rather than the fluctuating Coulomb forces with individual neighbors. Here, we present a simple continuum model for electrostatic correlations between finite-sized ions, which leads to a 4th order modified Poisson equation, convenient for the analysis of electrokinetic phenomena. When the mean-field approximation breaks down, e.g. due to large ion concentrations, large ion valences, and/or nanoscale confinement, the zeta potential loses its significance, and the model predicts that electro-osmotic flows are typically reduced - or even reversed - by correlation effects, compared to the prediction of the Helmholtz-Smoluchowski formula. This may help to explain the over-prediction of induced-charge electro-osmotic flows by classical models. An interesting limit of the model describes electro-osmosis in solvent-free ionic liquids and molten salts, which may be important in energy storage and electroactuation applications.

Storey, Brian; Bazant, Martin

2011-11-01

84

Electrokinetics of pure clay minerals revisited  

SciTech Connect

Clay minerals have long attracted the attention of colloid scientists. This paper considers, specifically, their important role in the transport of various contaminants from land to sea, e.g., metal ions and organic detrital and man-made material in watercourses. Advance in experimental techniques have enabled precise characterization of clays and then electrokinetic experiments at high electrolyte concentrations, such as in seawater. Three of the most important clay minerals encountered in suspended matter in natural waters, montmorillonite, illite, and chlorite, were prepared in a very pure state. Electrokinetic experiments were done in pure aqueous single and complex electrolyte solutions and in solutions in which natural organic matter was simulated using a humic substance, fulvic acid, of defined provenance and properties, typical of riverine waters. An isoelectric point was found at pH 5.0 {+-} 0.2 for chlorite; none were found for illite and montmorillonite. Only Ca{sup 2+} showed a charging effect on chlorite, indeed a reversal of sign from negative to positive at 1 {times} 10{sup {minus}3} mol dm{sup {minus}3}. Addition of fulvic acid affected only chlorite, illite less, and Na montmorillonite not at all.

Sondi, I.; Biscan, J.; Pravdic, V. [Rudjer Boskovic Inst., Zagreb (Croatia). Center for Marine Research

1996-03-25

85

Electrokinetic decontamination of concrete. Final report, August 3, 1993--September 15, 1996  

SciTech Connect

The ELECTROSORB{reg_sign} {open_quotes}C{close_quotes} process is an electrokinetic process for decontaminating concrete. ELECTROSORB{reg_sign} {open_quotes}C{close_quotes} uses a carpet-like extraction pad which is placed on the contaminated concrete surface. An electrolyte solution is circulated from a supporting module. This module keeps the electrolyte solution clean. The work is advancing through the engineering development stage with steady progress toward a full scale demonstration unit which will be ready for incorporation in the DOE Large Scale Demonstration Program by Summer 1997. A demonstration was carried out at the Mound Facility in Miamisburg, Ohio, in June 1996. Third party verification by EG&G verified the effectiveness of the process. Results of this work and the development work that proceeded are described herein.

NONE

1998-12-31

86

Removal of Mercury from Clayey Soils Using Electrokinetics  

Microsoft Academic Search

Numerous sites have been polluted with mercury as a result of accidental spills and improper disposal practices, and these mercury-contaminated sites may have adverse effects on human health and the environment. Innovative and cost-effective remediation techniques are urgently needed, and this study was performed to investigate the use of electrokinetics for mercury-contaminated soils. Initially, batch tests were performed on two

Krishna R. Reddy; Carlos Chaparro; Richard E. Saichek

2003-01-01

87

Incorporation of Source Material: The Effect of Instruction  

ERIC Educational Resources Information Center

An important aspect of advanced academic writing is the ability to incorporate source material. Yet this ability often poses considerable challenges for international ESL students. Although a number of scholars have called for the explicit teaching of how to acknowledge and incorporate source materials, research evidence on whether explicit…

Storch, Neomy

2012-01-01

88

Electrokinetic Separation of Heavy Metals from Wastewater Treatment Sludge  

Microsoft Academic Search

In the study, a preliminary experiment on the removal of heavy metals from industrial wastewater sludge was carried out to evaluate the feasibility of electrokinetic separation. Four different types of processing fluid—tap water, ethylenediaminetetraacetic acid (EDTA), citric acid (CA), and 0.1 M nitric acid—were tested. EDTA was found to be the most effective agent within the set of chemicals tested for

Seon-Young Park; Geun-Yong Park; Do-Hyung Kim; Jung-Seok Yang; Kitae Baek

2010-01-01

89

Analysis of Effects of Impurities Intentionally Incorporated into Silicon.  

National Technical Information Service (NTIS)

A methodology was developed and implemented to allow silicon samples containing intentionally incorporated impurities to be fabricated into finished solar cells under carefully controlled conditions. The electrical and spectral properties were then measur...

F. Uno

1977-01-01

90

EFFECT OF pH ON THE ELECTROKINETIC AND LIGHT SCATTERING PROPERTIES OF PEA THYLAKOIDS IN THE PRESENCE OF PHYTOHEMAGGLUTININ  

Microsoft Academic Search

Summary. We studied the effect of phytohemagglutinin on the surface charge density and 90° light scattering of pea thylakoids as a function of pH (from pH 6.0 to pH 7.8). These pH-dependent modifications were interpreted in terms of the membrane conformational changes. Lectin induced a decrease in LS level due to the increase in aggregation of the particles at all

Virjinia Doltchinkova; Maya Lambreva

91

Electrokinetic effect of the endothelial glycocalyx layer on two-phase blood flow in small blood vessels.  

PubMed

Blood flow behaves differently at the microvascular level than they do at upper levels of circulating systems. The endothelial glycocalyx layer on the luminal surface of blood vessels plays a significant role in regulating blood flow and blood cell movement in microvascular networks. For instance, previous experimental studies showed that the endothelial glycocalyx layer causes additional resistance to blood flow in small blood vessels. One of the important facts of the endothelial glycocalyx layer is that this layer is highly negatively charged. The question remains: do these electrostatic charges retard blood flow in small blood vessels according to the electroviscous effect? Here, a theoretical model is proposed to investigate the electrochemical effects of the endothelial glycocalyx layer on two-phase non-Newtonian blood flow in small blood vessels. Results show that electrostatic charges on the endothelial glycocalyx layer induce negligible effect to blood flow. Therefore, we can attribute the cause of additional resistance by the endothelial glycocalyx layer mainly to other mechanisms, such as, the glycocalyx constituted proteins acting as a flow barrier. PMID:19362568

Liu, Mei; Yang, Jun

2009-04-10

92

Nonlinear electrokinetics at large voltages  

NASA Astrophysics Data System (ADS)

The classical theory of electrokinetic phenomena assumes a dilute solution of point-like ions in chemical equilibrium with a surface whose double-layer voltage is of order the thermal voltage, kBT/e=25 mV. In nonlinear 'induced-charge' electrokinetic phenomena, such as ac electro-osmosis, several volts ?100kBT/e are applied to the double layer, and the theory breaks down and cannot explain many observed features. We argue that, under such a large voltage, counterions 'condense' near the surface, even for dilute bulk solutions. Based on simple models, we predict that the double-layer capacitance decreases and the electro-osmotic mobility saturates at large voltages, due to steric repulsion and increased viscosity of the condensed layer, respectively. The former suffices to explain observed high-frequency flow reversal in ac electro-osmosis; the latter leads to a salt concentration dependence of induced-charge flows comparable to experiments, although a complete theory is still lacking.

Bazant, Martin Z.; Sabri Kilic, Mustafa; Storey, Brian D.; Ajdari, Armand

2009-07-01

93

Electrokinetics of polar liquids in contact with nonpolar surfaces.  

PubMed

Zeta potentials of several polar protic (water, ethylene glycol, and formamide) as well as polar aprotic (dimethyl sulfoxide) liquids were measured in contact with three nonpolar surfaces using closed-cell electroosmosis. The test surfaces were chemisorbed monolayers of alkyl siloxanes, fluoroalkyl siloxanes, and polydimethylsiloxanes (PDMS) grafted on glass slides. All these liquids exhibited substantial electrokinetics in contact with the nonpolar surfaces with these observations: the electrokinetic effect on the fluorocarbon-coated surface is the strongest and on a PDMS grafted surface, the effect is the weakest. Even though these hygroscopic liquids contain small amounts of water, the current models of charging based on the adsorption of hydroxide ions at the interface or the dissociation of pre-existing functionalities (e.g., silanol groups) appear to be insufficient to account for the various facets of the experimental observations. The results illustrate how ubiquitous the phenomenon of electrokinetics is with polar liquids contacting such apparently passive nonpolar surfaces. We hope that these results will inspire further experimental and theoretical studies in this important area of research that has potential practical implications. PMID:23701297

Lin, Chih-Hsiu; Ferguson, Gregory S; Chaudhury, Manoj K

2013-06-07

94

Ion exclusion and electrokinetic effects resulting from electro-osmotic flow of salt solutions in charged silica nanopores.  

PubMed

Silica nanopores are the focus of significant scientific interest due to their potential in a wide variety of applications including desalination membranes. In this paper, the results of extensive all-atom molecular dynamics simulations of the electro-osmotic flow of 0.5 M monovalent (NaCl) and divalent (CaCl(2)) ionic solutions through cylindrical charged silica nanopores are presented. The silica nanopores are produced such that they capture the experimentally observed interfacial properties. The results provide an atomistic description of the ion transport through pores of diameters of 1.5 nm, 2.0 nm, 2.5 nm and 3.0 nm. In doing so, the effect of pore size on ion pairing, ion hydration, and water orientation for each ionic solution was investigated. Also, the transport of the ions through the nanopores is studied, and it is found that in the monovalent solutions the Cl(-) ions are excluded from the nanopores of all sizes. Whereas in the divalent solutions, there is no such preferential exclusion of either ion. This is due to the fact that the interfacial charge is fully compensated for by the Ca(2+) ions while it is not the case for the Na(+) ions. PMID:22441317

Haria, Neil R; Lorenz, Christian D

2012-03-22

95

ELECTROKINETIC REMEDIATION: BASICS AND TECHNOLOGY STATUS  

EPA Science Inventory

Electrokinetic soil processing is a controlled application of electrical migration and electroosmosis together with the electrolysis reactions. lectroosmosis is one of the different transport processes generated in soils under an electric current. lectroosmosis and electrophoresi...

96

Capillary Separation: Micellar Electrokinetic Chromatography  

NASA Astrophysics Data System (ADS)

Micellar electrokinetic chromatography (MEKC), a separation mode of capillary electrophoresis (CE), has enabled the separation of electrically neutral analytes. MEKC can be performed by adding an ionic micelle to the running solution of CE without modifying the instrument. Its separation principle is based on the differential migration of the ionic micelles and the bulk running buffer under electrophoresis conditions and on the interaction between the analyte and the micelle. Hence, MEKC's separation principle is similar to that of chromatography. MEKC is a useful technique particularly for the separation of small molecules, both neutral and charged, and yields high-efficiency separation in a short time with minimum amounts of sample and reagents. To improve the concentration sensitivity of detection, several on-line sample preconcentration techniques such as sweeping have been developed.

Terabe, Shigeru

2009-07-01

97

Convective instability of electrokinetic flows in a cross-shaped microchannel  

NASA Astrophysics Data System (ADS)

We present a parametric experimental study of convective electrokinetic instability (EKI) in an isotropically etched, cross-shaped microchannel using quantitative epifluorescence imaging. The base state is a three-inlet, one-outlet electrokinetic focusing flow configuration where the centre sample stream and sheath flows have mismatched ionic conductivities. Electrokinetic flows with conductivity gradients become unstable when the electroviscous stretching and folding of conductivity interfaces grows faster than the dissipative effect of molecular diffusion. Scalar images, critical applied fields required for instability, and temporal and spatial scalar energy are presented for flows with a wide range of applied d.c. electric field and centre-to-sheath conductivity ratios. These parameters impose variations of the electric Rayleigh number across four orders of magnitude. We introduce a scaling for charge density in the bulk fluid as a function of local maximum conductivity gradients in the flow. This scaling shows that the flow becomes unstable at a critical electric Rayleigh number (Ra_{e, ?} {=} 205) and applies to a wide range of applied field and centre-to-sheath conductivity ratios. This work is relevant to on-chip electrokinetic flows with conductivity gradients such as field amplified sample stacking, flow at the intersections of multi-dimensional assays, electrokinetic control and separation of sample streams with poorly specified chemistry, and low-Reynolds number micromixing.

Posner, Jonathan D.; Santiago, Juan G.

2006-05-01

98

Electrokinetic focusing and separation of mammalian cells in conductive biological fluids.  

PubMed

Active manipulation of cells, such as trapping, focusing, and isolation, is essential for various bioanalytical applications. Herein, we report a hybrid electrokinetic technique for manipulating mammalian cells in physiological fluids. This technique applies a combination of negative dielectrophoretic force and hydrodynamic drag force induced by electrohydrodynamics, which is effective in conductive biological fluids. With a three-electrode configuration, the stable equilibrium positions of cells can be adjusted for separation and focusing applications. Cancer cells and white blood cells can be positioned and isolated into specific locations in the microchannel under both static and dynamic flow conditions. To investigate the sensitivity of the hybrid electrokinetic process, AC voltage, frequency, and bias dependences of the cell velocity were studied systematically. The applicability of the hybrid electrokinetic technique for manipulating cells in physiological samples is demonstrated by continuous focusing of human breast adenocarcinoma spiked in urine, buffy coats, and processed blood samples with 98% capture efficiency. PMID:22937529

Gao, Jian; Riahi, Reza; Sin, Mandy L Y; Zhang, Shufeng; Wong, Pak Kin

2012-08-31

99

Incorporating long-term effects in determining the effectiveness of different types of online advertising  

Microsoft Academic Search

Although online advertising has become a full member of the marketing mix and is still growing in importance, studies of long-term,\\u000a or lagged, advertising effects have generally either neglected online advertising channels or have treated online advertising\\u000a as one homogeneous block. We analyze the short- and long-term effectiveness of different types of online advertising channels\\u000a by incorporating separate time lags

Ralph Breuer; Malte Brettel; Andreas Engelen

2011-01-01

100

Electrokinetic Remediation: I. Modeling of simple systems  

SciTech Connect

A one-dimensional model is developed for simulating the electrokinetic treatment of saturated porous media contaminated with an ionic salt. Simulations of simple, unenhanced electrokinetic treatment for the removal of a nonamphoteric salt such as cadmium sulfate exhibit a severe drop-off in electric current and in remediation rate after about 50-60% of the cation has been removed. Simulation of electrokinetic treatment in which the OH{sup -} generated in the cathode compartment is partially neutralized by the addition of acid show rapid and complete removal of the cation. Partial neutralization of H{sup +} in the anode compartment by addition of base results in immobilization of the toxic metal as the solid hydroxide, although this should be a useful technique for the removal of arsenate and selenate.

Wilson, D.J. [Vanderbilt Univ., Nashville, TN (United States); Rodriguez-Maroto, J.M.; Gomez-Lahoz, C. [Universidad de Malaga (Spain)

1995-09-01

101

Separation of estrogens by micellar electrokinetic chromatography.  

PubMed

Capillary electrophoresis of the sex hormone estrogens using different buffer components was investigated. Free zone electrophoresis with 10 mM phosphate buffer (pH 11.5) or 10 mM phosphate buffer with 10-20% methanol was not effective in separating the ten estrogens used in this study. However, nine estrogens were resolved by micellar electrokinetic chromatography using a 10 mM borate buffer (pH 9.2) containing 100 mM sodium cholate. In addition, some estrogens were partially separated using sodium dodecyl sulfate (SDS) micellar buffers; however, the addition of modifiers such as organic solvents or cyclodextrins improved resolutions significantly. Using a 10 mM phosphate buffer (pH 7.0) containing 50 mM SDS and 20% methanol, or a 10 mM borate buffer (pH 9.2) containing 50 mM SDS and 20 mM gamma-cyclodextrin, all ten of the tested estrogens were separated. However, the cyclodextrin-modified buffer allowed faster separation. PMID:7881538

Chan, K C; Muschik, G M; Issaq, H J; Siiteri, P K

1995-01-20

102

Kinematic effect of MGHL incorporation into Bankart repair.  

PubMed

Surgical treatment for traumatic shoulder instability has progressed in tandem with the evolution of the current understanding of the anatomy and biomechanics of the shoulder. Proponents of incorporating the middle glenohumeral ligament (MGHL) in Bankart repair believe this technique could increase repair strength. The purpose of this biomechanical study was to compare the range of motion and humeral head kinematic changes that result from including the MGHL in a Bankart repair in an effort to identify possible changes in shoulder biomechanics as a result of this addition in surgical repair.Six cadaveric shoulders were tested in 4 conditions: intact, Bankart lesion, repair excluding the MGHL, and repair including the MGHL. Each condition was tested for range of motion, glenohumeral translation, and humeral head apex position. Standard Bankart repair and repair with MGHL inclusion resulted in decreased range of motion, but no statistically significant difference was found between the 2 repair types (P=.846). Anterior translation was significantly reduced with both the Bankart repair (4.8 ± .9; P=.049) and included MGHL repair (4.6 ± 0.9; P=.029). No statistically significant difference was found between both repairs (P=.993). Although both repairs showed posterior displacement of the humeral head apex when in external rotation, this trend only reached statistical significance when compared with the Bankart lesion in 90° of external rotation (P=.0456); however, no significant difference was found between the 2 repairs (P=.999). Inclusion or exclusion of the MGHL in a Bankart repair does not significantly affect the range of motion, translation, or kinematics of the glenohumeral joint. PMID:23672898

Garber, Alexander C; Argintar, Evan; Shin, Sang-Jin; McGarry, Michelle H; Tibone, James E; Lee, Thay Q

2013-05-01

103

Incorporating Teacher Effectiveness into Teacher Preparation Program Evaluation  

ERIC Educational Resources Information Center

|New federal and state policies require that teacher preparation programs (TPP) be held accountable for the effectiveness of their graduates as measured by test score gains of the students they teach. In this article, the authors review the approaches taken in several states that have already estimated TPP effects and analyze the proposals for…

Henry, Gary T.; Kershaw, David C.; Zulli, Rebecca A.; Smith, Adrienne A.

2012-01-01

104

Magneto-Optical Kerr Effects of Yttrium-Iron Garnet Thin Films Incorporating Gold Nanoparticles  

Microsoft Academic Search

We report an experimental study on magneto-optical (MO) Kerr effects of yttrium-iron garnet (YIG) thin films incorporating Au nanoparticles. The polar MO Kerr spectra in the wavelength between 400 and 800 nm show that, by incorporating the Au nanoparticles, Kerr rotation angles become negative values in the region, where the localized surface plasmon polariton (SPP) resonance of the Au nanoparticles

Satoshi Tomita; Takeshi Kato; Shigeru Tsunashima; Satoshi Iwata; Minoru Fujii; Shinji Hayashi

2006-01-01

105

Effect of Incorporating Adaptive Functioning Scores on the Prevalence of Intellectual Disability  

ERIC Educational Resources Information Center

Surveillance and epidemiologic research on intellectual disability often do not incorporate adaptive functioning (AF) data. Exclusion of AF data leads to overestimation of the prevalence of intellectual disability, the extent of which is not known. In this study, the authors evaluated the effect of incorporating AF data on overall intellectual…

Obi, Obianuju; Braun, Kim Van Naarden; Baio, Jon; Drews-Botsch, Carolyn; Devine, Owen; Yeargin-Allsopp, Marshalyn

2011-01-01

106

Effect of Incorporating Adaptive Functioning Scores on the Prevalence of Intellectual Disability  

ERIC Educational Resources Information Center

|Surveillance and epidemiologic research on intellectual disability often do not incorporate adaptive functioning (AF) data. Exclusion of AF data leads to overestimation of the prevalence of intellectual disability, the extent of which is not known. In this study, the authors evaluated the effect of incorporating AF data on overall intellectual…

Obi, Obianuju; Braun, Kim Van Naarden; Baio, Jon; Drews-Botsch, Carolyn; Devine, Owen; Yeargin-Allsopp, Marshalyn

2011-01-01

107

Effect of ethanolamine on choline uptake and incorporation into phosphatidylcholine in human Y79 retinoblastoma cells  

Microsoft Academic Search

The effect of physiological concentrations of etha- nolamine on choline uptake and incorporation into phosphati- dylcholine was investigated in human Y79 retinoblastoma cells, a multipotential, undifferentiated retinal cell line that has re- tained many neural characteristics. These cells have a high-af- finity uptake system for choline, and the majority of the choline taken up was incorporated into phosphatidylcholine via the

Mark A. Yorek; Joyce A. Dunlap; Arthur A. Spector; Barry H. Ginsberg

108

Incorporation of Dietary Elaidic Acid in Tissues and Effects on Fatty Acid Distribution.  

National Technical Information Service (NTIS)

The incorporation of dietary elaidic acid into rat tissue and its effect on fatty acid distribution was studied with the use of infrared spectrophotometry and gas-liquid chromatography. Elaidic acid was incorporated into all of the 3 types of tissue analy...

W. J. Decker W. Mertz

1965-01-01

109

Extension of elution range in micellar electrokinetic capillary chromatography  

SciTech Connect

The authors have successfully demonstrated one approach to extend elution range in micellar electrokinetic capillary chromatography (MECC). By silanating the surfaces of fused-silica capillaries with trimethylchlorosilane (TMCS) the authors lowered electroosmotic flow velocity and, more importantly, the net flow velocity of the micelle phase, thereby increasing elution range. This is accomplished at the expense of a loss in column efficiency which primarily results from solute-wall interactions. Addition of 2-propanol to the mobile phase serves to minimize this effect, thereby restoring much of the efficiency lost in the process.

Balchunas, A.T.; Sepaniak, M.J.

1987-05-15

110

Induced-Charge Electrokinetic Phenomena: Theory and Microfluidic Applications  

Microsoft Academic Search

We give a general, physical description of ``induced-charge electro-osmosis''\\u000a(ICEO), the nonlinear electrokinetic slip at a polarizable surface, in the\\u000acontext of some new techniques for microfluidic pumping and mixing. ICEO\\u000ageneralizes ``AC electro-osmosis'' at micro-electrode arrays to various\\u000adielectric and conducting structures in weak DC or AC electric fields. The\\u000abasic effect produces micro-vortices to enhance mixing in microfluidic

Martin Z. Bazant; Todd M. Squires

2004-01-01

111

Microemulsion electrokinetic chromatography in suppressed electroosmotic flow environment  

Microsoft Academic Search

Microemulsion electrokinetic chromatography (MEEKC) was carried out in a pH 2.5 phosphate buffer to effectively suppress the electroosmotic flow (EOF). With 66.6% (w\\/w) 25 mM phosphate buffer pH 2.5, 20.0% (w\\/w) 2-propanol, 6.6% (w\\/w) 1-butanol, 6.0% (w\\/w) sodium lauryl sulphate (SDS), and 0.8% (w\\/w) n-octane as the separation medium, the fat-soluble vitamins A palmitate, E acetate, and D3 were baseline

Stig Pedersen-Bjergaard; Øystein Næss; Siver Moestue; Knut Einar Rasmussen

2000-01-01

112

Electrokinetic remediation of anionic contaminants from unsaturated soils  

SciTech Connect

Heavy-metal contamination of soil and groundwater is a widespread problem in the DOE weapons complex, and for the nation as a whole. Electrokinetic remediation is one possible technique for in situ removal of such contaminants from unsaturated soils. In previous studies at Sandia National Laboratories, the electromigration of chromate ions and anionic dye ions have been demonstrated. This paper reports on a series of experiments that were conducted to study the effect of moisture content on the electromigration rate of anionic contaminants in unsaturated soil and determine the limiting moisture content for which electromigration occurs.

Lindgren, E.R.; Kozak, M.W. [Sandia National Labs., Albuquerque, NM (United States); Mattson, E.D. [SAT-UNSAT, Inc., Albuquerque, NM (United States)

1992-11-01

113

Electrokinetic remediation of anionic contaminants from unsaturated soils  

SciTech Connect

Heavy-metal contamination of soil and groundwater is a widespread problem in the DOE weapons complex, and for the nation as a whole. Electrokinetic remediation is one possible technique for in situ removal of such contaminants from unsaturated soils. In previous studies at Sandia National Laboratories, the electromigration of chromate ions and anionic dye ions have been demonstrated. This paper reports on a series of experiments that were conducted to study the effect of moisture content on the electromigration rate of anionic contaminants in unsaturated soil and determine the limiting moisture content for which electromigration occurs.

Lindgren, E.R.; Kozak, M.W. (Sandia National Labs., Albuquerque, NM (United States)); Mattson, E.D. (SAT-UNSAT, Inc., Albuquerque, NM (United States))

1992-01-01

114

Electrokinetically synchronized polymerase chain reaction microchip fabricated in polycarbonate.  

PubMed

This paper presents a novel method for DNA thermal amplification using the polymerase chain reaction (PCR) in an electrokinetically driven synchronized continuous flow PCR (EDS-CF-PCR) configuration carried out in a microfabricated polycarbonate (PC) chip. The synchronized format allowed patterning a shorter length microchannel for the PCR compared to nonsynchronized continuous flow formats, permitting the use of smaller applied voltages when the flow is driven electrically and also allowed flexibility in selecting the cycle number without having to change the microchip architecture. A home-built temperature control system was developed to precisely configure three isothermal zones on the chip for denaturing (95 degrees C), annealing (55 degrees C), and extension (72 degrees C) within a single-loop channel. DNA templates were introduced into the PCR reactor, which was filled with the PCR cocktail, by electrokinetic injection. The PCR cocktail consisted of low salt concentrations (KCl) to reduce the current in the EDS-CF-PCR device during cycling. To control the EOF in the PC microchannel to minimize dilution effects as the DNA "plug" was shuttled through the temperature zones, Polybrene was used as a dynamic coating, which resulted in reversal of the EOF. The products generated from 15, 27, 35, and 40 EDS-CF-PCR amplification cycles were collected and analyzed using microchip electrophoresis with LIF detection for fragment sizing. The results showed that the EDS-CF-PCR format produced results similar to that of a conventional block thermal cycler with leveling effects observed for amplicon generation after approximately 25 cycles. To the best of our knowledge, this is the first report of electrokinetically driven synchronized PCR performed on chip. PMID:15649068

Chen, Jifeng; Wabuyele, Musundi; Chen, Hengwu; Patterson, Donald; Hupert, Mateusz; Shadpour, Hamed; Nikitopoulos, Dimitris; Soper, Steven A

2005-01-15

115

Separation of tea polyphenols using micellar electrokinetic chromatography with diode array detection  

Microsoft Academic Search

Micellar electrokinetic capillary chromatography has been investigated for its potential in the analysis of polyphenols in tea. Conditions have been optimised by systematically examining the effect of inorganic buffer, micelle, borate and organic solvent concentration. These conditions have then been used to analyse a range of tea types, including an instant green, Darjeeling and black Assam tea. The more fully

P. J Larger; A. D Jones; C Dacombe

1998-01-01

116

Quantitative determination of amygdalin epimers by cyclodextrin-modified micellar electrokinetic chromatography  

Microsoft Academic Search

A new capillary electrophoresis method was developed for the quantitative determination of the amygdalin epimers, amygdalin and neoamygdalin, which are biologically significant constituents in the crude drugs, namely Persicae Semen and Armeniacae Semen. The effects of surfactants, additives and other analytical parameters were studied. As a result, the resolution of two epimers was performed by cyclodextrin-modified micellar electrokinetic chromatography with

Takafumi Isozaki; Yutaka Matano; Keiichi Yamamoto; Noboru Kosaka; Tadato Tani

2001-01-01

117

Electrokinetic framework of dielectrophoretic deposition devices  

NASA Astrophysics Data System (ADS)

Numerical modeling and experiments are performed investigating the properties of a dielectrophoresis-based deposition device, in order to establish the electrokinetic framework required to understand the effects of applied inhomogeneous electric fields while moving particles to desired locations. By capacitively coupling electrodes to a conductive substrate, the controlled large-scale parallel dielectrophoretic assembly of nanostructures in individually accessible devices at a high integration density is accomplished. Thermal gradients in the solution, which give rise to local permittivity and conductivity changes, and velocity fields are solved by coupling electric, thermal, and fluid-mechanical equations. The induced electrothermal flow (ETF) causes vortices above the electrode gap, attracting particles, such as single-walled carbon nanotubes (SWNTs), before they are trapped by the dielectrophoretic force and deposit across the electrodes. Long-range carbon nanotube transport is governed by hydrodynamic effects, while local trapping is dominated by dielectrophoretic forces in low concentration SWNT dispersions. Results show that by decreasing the ac frequency ac electroosmosis on the metallic electrodes occurs due to the emergence of an electric double layer, disturbing the initial flow pattern of the system. By superimposing a dc potential offset, a generated tangential electroosmotic fluid flow in the dielectric electrode gap also disrupts the ETF. Capacitive coupling is most efficient in the high frequency regime where it is the dominating impedance contribution. Understanding the occurrence and interaction of these different effects, including a self-limiting integration mechanism for individual nanostructures, allows an increased deposition yield at overall lower electric field strengths through a prudent choice of electric field parameters. The findings provide important avenues toward gentler particle handling, without direct current throughput, a relevant aspect for limiting process effects during device fabrication, all while increasing dielectrophoretic deposition efficiency in nanostructured networks.

Burg, Brian R.; Bianco, Vincenzo; Schneider, Julian; Poulikakos, Dimos

2010-06-01

118

Mutagenic Effect of Radionuclides Incorporated into DNA of Drosphila Melanogaster. Progress Report, 1976--1977.  

National Technical Information Service (NTIS)

Progress is reported on studies of the genetic effect of tritium incorporated into DNA of Drosophila melanogaster. Following a short pulse exposure to tritium-labeled uridine most of the radioactivity appeared in RNA; however, the turnover of radioactivit...

W. R. Lee

1977-01-01

119

Determining the Effectiveness of Incorporating Geographic Information Into Vehicle Performance Algorithms.  

National Technical Information Service (NTIS)

This thesis presents a research study using one year of driving data obtained from plug-in hybrid electric vehicles (PHEV) located in Sacramento and San Francisco, California to determine the effectiveness of incorporating geographic information into vehi...

S. White

2012-01-01

120

Effectively incorporating selected multimedia content into medical publications  

PubMed Central

Until fairly recently, medical publications have been handicapped by being restricted to non-electronic formats, effectively preventing the dissemination of complex audiovisual and three-dimensional data. However, authors and readers could significantly profit from advances in electronic publishing that permit the inclusion of multimedia content directly into an article. For the first time, the de facto gold standard for scientific publishing, the portable document format (PDF), is used here as a platform to embed a video and an audio sequence of patient data into a publication. Fully interactive three-dimensional models of a face and a schematic representation of a human brain are also part of this publication. We discuss the potential of this approach and its impact on the communication of scientific medical data, particularly with regard to electronic and open access publications. Finally, we emphasise how medical teaching can benefit from this new tool and comment on the future of medical publishing.

2011-01-01

121

Micellar electrokinetic chromatography Perspectives in drug analysis  

Microsoft Academic Search

Micellar electrokinetic chromatography (MEKC) has become a popular mode among several capillary electromigration techniques. Most drug analyses can be performed by using MEKC because of its wide applicability. Enantiomer separation, separation of closely related peptides and isotopic compounds, separation of very complex mixtures, determination of drugs in the biological samples, etc., can be succesfully achieved by MEKC. This review surveys

Nishi Hiroyuki; Shigeru Terabe

1996-01-01

122

Opto-electrokinetic manipulation technique for highperformance  

SciTech Connect

This communication first demonstrates bio-compatibility of a recently developed opto-electrokinetic manipulation technique, using microorganisms. Aggregation, patterning, translation, trapping and size-based separation of microorganisms performed with the technique firmly establishes its usefulness for development of a high-performance on-chip bioassay system.

Kwon, Jae-Sung [Purdue University; Ravindranath, Sandeep [Purdue University; Kumar, Aloke [ORNL; Irudayaraj, Joseph [Purdue University; Wereley, Steven T. [Purdue University

2012-01-01

123

Electrostatic and electrokinetic contributions to the elastic moduli of a driven membrane  

NASA Astrophysics Data System (ADS)

We discuss the electrostatic contribution to the elastic moduli of a cell or artificial membrane placed in an electrolyte and driven by a DC electric field. The field drives ion currents across the membrane, through specific channels, pumps or natural pores. In steady state, charges accumulate in the Debye layers close to the membrane, modifying the membrane elastic moduli. We first study a model of a membrane of zero thickness, later generalizing this treatment to allow for a finite thickness and finite dielectric constant. Our results clarify and extend the results presented by D. Lacoste, M. Cosentino Lagomarsino, and J.F. Joanny (EPL 77, 18006 (2007)), by providing a physical explanation for a destabilizing term proportional to k ? 3 in the fluctuation spectrum, which we relate to a nonlinear (E2) electrokinetic effect called induced-charge electro-osmosis (ICEO). Recent studies of ICEO have focused on electrodes and polarizable particles, where an applied bulk field is perturbed by capacitive charging of the double layer and drives the flow along the field axis toward surface protrusions; in contrast, we predict “reverse” ICEO flows around driven membranes, due to curvature-induced tangential fields within a nonequilibrium double layer, which hydrodynamically enhance protrusions. We also consider the effect of incorporating the dynamics of a spatially dependent concentration field for the ion channels.

Lacoste, D.; Menon, G. I.; Bazant, M. Z.; Joanny, J. F.

2009-03-01

124

Enhancement of electrokinetic remediation of hyper-Cr(VI) contaminated clay by zero-valent iron.  

PubMed

This paper investigated the effectiveness of incorporating zero-valent iron (ZVI) into electrokinetic (EK) to remediate hyper-Cr(VI) contaminated clay (2497 mg/kg). A ZVI wall was installed in the center of the soil specimen and was filled with 1:1 (w/w) ratio of granular ZVI and sand. Results show that transport of H(+) is greatly retarded by the strong opposite migration of anionic chromate ions, whereupon a revered electroosmosis flow (EO) was resulted and alkaline zone across the specimen was developed promoting the release of Cr(VI) from the clay. Chromium removal was characterized by high Cr(VI) concentration occurred in the anolyte and the presence of Cr(III) precipitates in the catholyte. The Cr(VI) reduction efficiencies for the process without ZVI wall were 68.1 and 79.2% for 1 and 2V/cm, respectively. As ZVI wall was installed, the corresponding reduction efficiencies increased to 85.8 and 92.5%. The costs for energy and ZVI utilized in this process are US$ 41.0 and 57.5 per cubic meter for the system with electric gradient of 1 and 2V/cm, respectively. The role of ZVI wall effectively reducing Cr(VI) contamination and the operation simultaneous collection of Cr(VI) from the electrode reservoirs are two major advantages of this process. PMID:17485164

Weng, Chih-Huang; Lin, Yao-Tung; Lin, T Y; Kao, C M

2007-03-30

125

Sensitive enantioseparation by transient trapping-cyclodextrin electrokinetic chromatography.  

PubMed

An on-line sample preconcentration based on transient trapping was applied to cyclodextrin electrokinetic chromatography (CDEKC) to realize a highly sensitive chiral analysis in capillary electrophoresis. The partial introduction of a micellar solution before the electrokinetic injection of a sample solution provided the effective preconcentration and enantioseparation of chiral compounds, resulting in the up to 240-fold enhancements of peak intensity and 100-fold improvements of limit of detection of (R),(S)-1-aminoindan as the model analyte. The demonstrated method could be applied to the other pharmaceutical compounds, which allowed five chiral analytes to be resolved with 40- to 160-fold sensitivity enhancements at once. The enantioseparation efficiency of the proposed method was slightly lower as compared to the conventional CDEKC, while the acceptable baseline separations of enantiomers were obtained in transient trapping-CDEKC relative to the undesirable resolution in the CDEKC with other preconcentration techniques. Additionally, it was clarified that transient trapping-CDEKC was also applicable to the analysis of enantiomeric excess, providing the sensitive detection of 43ppb of (R)-chlorpheniramine in 5ppm (S)-chlorpheniramine solution commercially available. PMID:22959845

Sueyoshi, Kenji; Koino, Hiroshi; Kitagawa, Fumihiko; Otsuka, Koji

2012-08-27

126

Computing the Electrokinetic Response with Simple Models via Eigenvalue Decomposition  

NASA Astrophysics Data System (ADS)

The efficient solution of coupled hydrogeophysical problems both numerically and analytically is important to their use in parameter estimation. We present a general approach for decoupling the governing equations for groundwater flow and the associated electrokinetic problem. The approach can use either a symbolic or numerical eigenvector decomposition of the matrix that arises when writing the two equations in vector form. The two coupled problems, once uncoupled, can then be solved using any existing approaches for the simple non-coupled component problems. Solutions can be either analytic or numerical in nature with the effective parameters being computed in the decomposition. The final solution, in terms of the physical potentials of interest, is computed through a simple matrix multiplication. We solve the fully coupled electrokinetic problem (water flow driving electrical flow and electrical flow driving water flow) for a single layer using the Theis solution, and for multilayer problems using MODFLOW. The approach is quite general, with the main limitation being a required symmetry between the coupled processes in their differential equation (e.g., both processes must be governed by the diffusion equation). The solution obtained with this approach is shown to agree with that obtained by Malama et al. (2009). Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000

Kuhlman, K. L.; Malama, B.

2010-12-01

127

Preparation and evaluation of bonded linear polymethacrylate stationary phases for open tubular capillary electrokinetic chromatography  

SciTech Connect

A new procedure for the preparation of thick polymethacrylate films bonded in 25 {mu}m i.d. fused-silica capillaries is developed. The etched silica surface is first modified with an unsaturated organosilane, which is later incorporated into the polymer film. The capillary is then filled with a monomer solution, and polymerization is initiated by incubation at elevated temperature. This thermoinitiation method enables the use of ordinary polyimide-jacketed capillaries in preparing the columns. The effect of monomer concentration on the resulting polymer film was studied by open tubular capillary electrokinetic chromatography using p-hydroxybenzoates (parabens) as test solutes. Good separations were achieved using short capillaries. Run-to-run retention time reproducibility was excellent, with RSDs of 2% (n = 50) being representative. For the linear polymer films produced, retention of analytes increased as the monomer concentration increased to a certain value, at which point the capacity factors level off with further increases in monomer concentration. The electroosmotic flow velocity decreases with increasing monomer concentration. The efficiency for an unretained test probe (acetone) reaches 270 000 plates/m. 13 refs., 10 figs., 1 tab.

Tan, Z.J.; Remcho, V.T. [West Virginia Univ., Morgantown, WV (United States)

1997-02-15

128

Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part II: Coupling between ion mobility, electrolysis, and acid-base equilibria.  

PubMed

We present elements of electrolyte dynamics and electrochemistry relevant to microfluidic electrokinetics experiments. In Part I of this two-paper series, we presented a review and introduction to the fundamentals of acid-base chemistry. Here, we first summarize the coupling between acid-base equilibrium chemistry and electrophoretic mobilities of electrolytes, at both infinite and finite dilution. We then discuss the effects of electrode reactions on microfluidic electrokinetic experiments and derive a model for pH changes in microchip reservoirs during typical direct-current electrokinetic experiments. We present a model for the potential drop in typical microchip electrophoresis device. The latter includes finite element simulation to estimate the relative effects of channel and reservoir dimensions. Finally, we summarize effects of electrode and electrolyte characteristics on potential drop in microfluidic devices. As a whole, the discussions highlight the importance of the coupling between electromigration and electrophoresis, acid-base equilibria, and electrochemical reactions. PMID:19680571

Persat, Alexandre; Suss, Matthew E; Santiago, Juan G

2009-07-07

129

Effect of carbon incorporation on electrical properties of n-type GaN surfaces  

NASA Astrophysics Data System (ADS)

We intentionally incorporated carbon into n-GaN by high-temperature annealing of a SiNx/CNx/GaN structure to study the effect of unintentional carbon incorporation on the electrical properties of n-type GaN surfaces. X-ray photoelectron spectroscopy results showed outdiffusion of Ga atoms from the GaN surface during high-temperature annealing even when the SiNx layer was present. The current-voltage characteristics showed a drastic increase in current in the forward and reverse directions of the Schottky diode in the carbon-incorporated sample. They also showed no temperature dependence from 150 to 300 K. The current-voltage curves of the carbon-incorporated samples in the forward and reverse directions could be almost completely reproduced by assuming an exponentially decaying distribution from the surface for shallow donors.

Kimura, Takeshi; Hashizume, Tamotsu

2009-01-01

130

Remediating ethylbenzene-contaminated clayey soil by a surfactant-aided electrokinetic (SAEK) process.  

PubMed

The objectives of this research are to investigate the remediation efficiency and electrokinetic behavior of ethylbenzene-contaminated clay by a surfactant-aided electrokinetic (SAEK) process under a potential gradient of 2 Vcm(-1). Experimental results indicated that the type of processing fluids played a key role in determining the removal performance of ethylbenzene from clay in the SAEK process. A mixed surfactant system consisted of 0.5% SDS and 2.0% PANNOX 110 showed the best performance of ethylbenzene removed in the SAEK system. The removal efficiency of ethylbenzene was determined to be 63-98% in SAEK system while only 40% was achieved in an electrokinetic system with tap water as processing fluid. It was found that ethylbenzene was accumulated in the vicinity of anode in an electrokinetic system with tap water as processing fluid. However, the concentration front of ethylbenzene was shifted toward cathode in the SAEK system. The electroosmotic permeability and power consumption were 0.17 x 10(-6)-3.01 x 10(-6) cm(2)V(-1)s(-1) and 52-123 kW h m(-3), respectively. The cost, including the expense of energy and surfactants, was estimated to be 5.15-12.65 USD m(-3) for SAEK systems, which was 2.0-4.9 times greater than that in the system of electrokinetic alone (2.6 USD m(-3)). Nevertheless, by taking the remediation efficiency of ethylbenzene and the energy expenditure into account for the overall process performance evaluation, the system SAEK was still a cost-effective alternative treatment method. PMID:15312739

Yuan, Ching; Weng, Chih-Huang

2004-10-01

131

Quartz channel fabrication for electrokinetically driven separations  

NASA Astrophysics Data System (ADS)

For well resolved electrokinetic separation, we utilize crystalline quartz to micromachine a uniformly packed separation channel. Packing features are posts 5 micrometers on a side with 3 micrometers spacing and etched 42 micrometers deep. In addition to anisotropic wet etch characteristics for micromachining, quartz properties are compatible with chemical solutions, electrokinetic high voltage operation, and stationary phase film deposition. To seal these channels, we employ a room temperature silicon-oxynitride deposition to form a membrane, that is subsequently coated for mechanical stability. Using this technique, particulate issues and global warp, that make large area wafer bonding methods difficult, are avoided, and a room temperature process, in contrast to high temperature bonding techniques, accommodate preprocessing of metal films for electrical interconnect. After sealing channels, a number of macro- assembly steps are required to attach a micro-optical detection system and fluid interconnects.

Matzke, Carolyn M.; Arnold, D. W.; Ashby, Carol I.; Kravitz, Stanley H.; Warren, Mial E.; Bailey, C. G.

1998-09-01

132

Quartz Channel Fabrication for Electrokinetically Driven Separations  

SciTech Connect

For well resolved electrokinetic separation, we L tilize crystalline quartz to micromachine a uniformly packe Q&iKLmnel. Packing features are posts 5 Vm on a side with:} pm spacing and etched 42 Vm deep. In addition to anisotropic wet etch characteristics for micromachining, quartz propmties are compatible with chemical soiutioits, ekctrokinetic high voltage operation, and stationary phase film depositions. To seal these channels, we employ a room temperature silicon-oxynhride deposition to forma membrane, that is subsequently coated for mechanical stability. Using this technique, particulate issues and global warp, that make large area wafer bon ding methods difficult, are avoided, and a room temperature process, in contrast to high temperature bonding techniques, accommodate preprocessing of metal films for electrical interconnect. After sealing channels, a number of macro-assembly steps are required to attach a micro-optical detection system and fluid interconnects. Keywords: microcharmel, integrated channel, micromachined channel, packed channel, electrokinetic channel, eleetrophoretic channel

Arnold, D.W.; Ashby, C.I.H.; Bailey, C.G.; Kravitz, S.H., Warren, M.E.; Matzke, C.M.

1998-12-01

133

Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part I: Acid-base equilibria and pH buffers.  

PubMed

We review fundamental and applied acid-base equilibrium chemistry useful to microfluidic electrokinetics. We present elements of acid-base equilibrium reactions and derive rules for pH calculation for simple buffers. We also present a general formulation to calculate pH of more complex, arbitrary mixtures of electrolytes, and discuss the effects of ionic strength and temperature on pH calculation. More practically, we offer advice on buffer preparation and on buffer reporting. We also discuss "real world" buffers and likely contamination sources. In particular, we discuss the effects of atmospheric carbon dioxide on buffer systems, namely, the increase in ionic strength and acidification of typical electrokinetic device buffers. In Part II of this two-paper series, we discuss the coupling of acid-base equilibria with electrolyte dynamics and electrochemistry in typical microfluidic electrokinetic systems. PMID:19680570

Persat, Alexandre; Chambers, Robert D; Santiago, Juan G

2009-07-07

134

Sphalerite activation: Flotation and electrokinetic studies  

Microsoft Academic Search

Sphalerite is commonly floated in an alkaline environment and under such conditions the overall activation mechanism is obscured by the hydrolysis of Cu2+ and precipitation of Cu(OH)2.Electrokinetic and kinetic flotation tests showed that the activation of sphalerite is a two-stage process; the activation products formed on the surface of sphalerite in near neutral and in alkaline solutions in the first

J. S. Laskowski; Q. Liu; Y. Zhan

1997-01-01

135

Micellar electrokinetic capillary chromatography of macrolide antibiotics  

Microsoft Academic Search

The separation of tylosin by micellar electrokinetic capillary chromatography with a mixed micelle system is described. Good selectivity was obtained with sodium phosphate buffer (80 mM, pH 7.5) containing 20 mM sodium cholate and 7 mM cetyltrimethylammonium bromide (CTAB). This method permits tylosin to be separated from its closely related substances within 15 min. The influences of type of buffer,

K Tobback; Y.-M Li; N. Alberto Pizarro; I De Smedt; T Smeets; A Van Schepdael; E Roets; J Hoogmartens

1999-01-01

136

Microemulsion and micellar electrokinetic chromatography of steroids  

Microsoft Academic Search

A mixture of ten steroids was separated by microemulsion and micellar (SDS and glycodeoxyholate) electrokinetic chromatography systems. Separations were done on a 50 cm (to the detector) × 50 ?m I.D. fused-silica capillary. Complete separation of all the test compounds in the micellar mode was obtained with glycodeoxycholate (50 mM) in 25 mM borate buffer, pH 6.5, as the micelle-forming

L. Vomastová; I. Mikšík; Z. Deyl

1996-01-01

137

Magneto-optical Kerr effects of yttrium-iron garnet thin films incorporating gold nanoparticles.  

PubMed

We report an experimental study on magneto-optical (MO) Kerr effects of yttrium-iron garnet (YIG) thin films incorporating Au nanoparticles. The polar MO Kerr spectra in the wavelength between 400 and 800 nm show that, by incorporating the Au nanoparticles, Kerr rotation angles become negative values in the region, where the localized surface plasmon polariton (SPP) resonance of the Au nanoparticles is located. The anomalous Kerr rotation indicates a possible coupling between the MO Kerr effect of YIG and the SPP. A mechanism for the coupling is discussed. PMID:16712274

Tomita, Satoshi; Kato, Takeshi; Tsunashima, Shigeru; Iwata, Satoshi; Fujii, Minoru; Hayashi, Shinji

2006-04-28

138

Effect of Sb incorporation on the electronic structure of InAs quantum dots  

NASA Astrophysics Data System (ADS)

On the basis of optical characterization experiments and an eight band kp model, we have studied the effect of Sb incorporation on the electronic structure of InAs quantum dots (QDs). We have found that Sb incorporation in InAs QDs shifts the hole wave function to the center of the QD from the edges of the QD where it is otherwise pinned down by the effects of shear stress. The observed changes in the ground-state energy cannot merely be explained by a composition change upon Sb exposure but can be accounted for when the change in lateral size is taken into consideration. The Sb distribution inside the QDs produces distinctive changes in the density of states, particularly, in the separation between excitation shells. We find a 50% increase in the thermal escape activation energy compared with reference InAs quantum dots as well as an increment of the fundamental transition decay time with Sb incorporation. Furthermore, we find that Sb incorporation into quantum dots is strongly nonlinear with coverage, saturating at low doses. This suggests the existence of a solubility limit of the Sb incorporation into the quantum dots during growth.

Taboada, A. G.; Llorens, J. M.; Alonso-Álvarez, D.; Alén, B.; Rivera, A.; González, Y.; Ripalda, J. M.

2013-08-01

139

Cosolvent-enhanced electrokinetic remediation of soils contaminated with phenanthrene  

Microsoft Academic Search

This research was carried out to evaluate feasibility of using an electrokinetic technique to remove hydrophobic organic pollutants from soils, with the assistance of a cosolvent (n-butylamine, tetrahydrofuran, or acetone) added to the conducting fluid. The experiments were carried out on glacial till clay with phenanthrene as the test compound. Desorption equilibrium was investigated by batch tests. The electrokinetic experiments

An Li; Kent A. Cheung; Krishna R. Reddy

2000-01-01

140

FEASIBILITY OF ELECTROKINETIC SOIL REMEDIATION IN HORIZONTAL LASAGNA CELLS  

EPA Science Inventory

An integrated soil remediation technology called Lasagna has been developed that combines electrokinetics with treatment zones for use in low permeability soils where the rates of hydraulic and electrokinetic transport are too low to be useful for remediation of contaminants. The...

141

Effects of Incorporation Method of Ethoprop and Addition of Aldicarb on Potato Tuber Infection by Meloidogyne hapla.  

PubMed

The efficacy of controlling Meloidogyne hapla on potato with water incorporation of ethoprop was compared to physical incorporation before planting. The standard practice of aldicarb application for insect control was also evaluated for M. hapla suppression with and without ethoprop. Physical incorporation before planting by rototilling or discing reduced (P incorporation of ethoprop was not as effective as physical incorporation of ethoprop or postplant water incorporation of aldicarb and did not reduce (P

Ingham, R E; Morris, M; Newcomb, G B

1991-10-01

142

Removal and degradation of phenol in a saturated flow by in-situ electrokinetic remediation and Fenton-like process  

Microsoft Academic Search

In this laboratory study, a sandy loam soil saturated with phenol solution was treated by in-situ electrokinetics-Fenton process incorporated with a permeable reactive wall of scrap iron powder (SIP). The soil was contaminated and saturated with aqueous phenol solution of 90–115 mg\\/kg in concentration. It was then placed in a soil cell. The soil cell was assembled with an anode

Gordon C. C Yang; Yu-Wen Long

1999-01-01

143

Effect of surface incorporation of broiler litter applied to no-till cotton on runoff quality.  

PubMed

Surface application of broiler litter to no-till cotton could lead to degradation of water quality. Incorporation of broiler litter into the top surface soil (0.05 m) could alleviate this risk. A 2-yr field study was conducted on a silt loam upland soil to determine the effect of incorporation of broiler litter into the soil surface on nutrient and bacterial transport in runoff. The experimental design was a randomized complete block with four treatments and three replications. Treatments were (i) unfertilized control; (ii) surface-appliedbroiler litter at 7.8 Mg ha(-1) without incorporation; (iii) surface-applied broiler litter at 7.8 Mg ha(-1) with immediate incorporation; and (iv) inorganic fertilizer N (urea ammonium nitrate, 32% N) and inorganic fertilizer P (triple superphosphate) at the recommended rate. Phosphorus was surface appliedat 25 kg ha(-1) and N was injected at 101 kg ha(-1) into the soil using a commercial liquid fertilizer applicator. Runoff was collected from small runoff plots (2.4 m by 1.6 m) established at the bottom side of main plots (13.7 m by 6.0 m). Incorporation of broiler litter reduced total N (TN), NO3-N, water soluble P (WSP), and total P (TP) concentrations in runoffby 35, 25, 61, and 64%, respectively, and litter-associated bacteria by two to three orders of magnitude compared with unincorporated treatment. No significant difference in total suspended solids (TSS) in runoffwas obtained between incorporated and unincorporated treatments. Incorporation of broiler litter into the surface soil in the no-till system immediately after application minimized the potential risk for surface nutrient losses and bacteria transport in runoff. PMID:21520764

Adeli, A; Shankle, M W; Tewolde, H; Brooks, J P; Sistani, K R; McLaughlin, M R; Rowe, D E

144

A Theory-Based Parent Competency Model Incorporating Intervention Attendance Effects.  

ERIC Educational Resources Information Center

Tests a parent competency model incorporating the effects of attendance in a parenting skills training intervention. Subjects (n=209) participated in a controlled study to test the model. Results generally supported the model for both mothers and fathers. Child management behaviors mediated parent conventionality and intervention attendance…

Spoth, Richard; Redmond, Cleve

1996-01-01

145

The Effect of Incorporating Cooperative Learning Principles in Pair Programming for Student Teachers  

ERIC Educational Resources Information Center

|Based on their quantitative and qualitative investigations, the authors conclude that pair programming as a strategy for teaching student teachers could be made more effective through the incorporation of principles associated with cooperative learning. They substantiate this claim by referring to a literature study about the advantages and…

Mentz, E.; van der Walt, J. L.; Goosen, L.

2008-01-01

146

Effect of baking on dietary fibre and phenolics of muffins incorporated with apple skin powder  

Microsoft Academic Search

Apple fruit skin, a rich source of dietary fibre and phenolics, is a by-product of apple processing. The effect of baking on the dietary fibre, phenolics, and total antioxidant capacity was investigated using a model system of muffins incorporated with dried apple skin powder (ASP) as a value-added food ingredient. The blanched, dehydrated, and ground ASP contained approximately 41% total

H. P. Vasantha Rupasinghe; Laixin Wang; Gwendolyn M. Huber; Nancy L. Pitts

2008-01-01

147

An analytical model for laser drilling incorporating effects of exothermic reaction, pulse width and hole geometry  

Microsoft Academic Search

An analytical model is presented which incorporates the effects of using O2 as assist gas. The contribution of the enthalpy of oxidation used in the model was determined experimentally by capturing the ejected melt and measuring the volume percentage of oxidation. The formulation of recoil pressure used in the model takes into account hole diameter and depth, and the associated

G. K. L. Ng; P. L. Crouse; L. Li

2006-01-01

148

Reactions in glass ionomer cements: V. Effect of incorporating tartaric acid in the cement liquid.  

PubMed

A description is give of the effect on the ASPA cement reaction of tartaric acid incorporated in the cement liquid. Tartaric acid acts as an accelerator that aids in the extraction of ions from the aluminosilicate glass and facilitates their binding to the polyanion chains. Postgelation hardening is significantly increased. Working time is unaffected possibly because cations are initially present as complexes. PMID:187629

Crisp, S; Wilson, A D

149

Effect of direct incorporation of poultry litter on phosphorus leaching from coastal plain soils  

Technology Transfer Automated Retrieval System (TEKTRAN)

Management of poultry litter on the Delmarva Peninsula is critical to reducing phosphorus loads to the Chesapeake Bay. New poultry litter incorporation technologies have shown promise at reducing phosphorus losses, but their effectiveness has not been tested in this environmentally-sensitive region...

150

Effects of silver incorporation on the dielectric and ferroelectric properties of PMN–PNN–PZT ceramics  

Microsoft Academic Search

The effects of silver addition on the sintering behavior, the dielectric, and ferroelectric properties of PMN–PNN–PZT piezoelectric ceramics for multilayer piezoelectric transformers were investigated. A small amount of silver promoted the sintering, but with more silver the density of the samples decreased. The silver incorporation affected the dielectric and ferroelectric properties of the samples. The dielectric constant presented an interesting

Ruzhong Zuo; Longtu Li; Xiaobing Hu; Zhilun Gui

2001-01-01

151

Ring stains in the presence of electrokinetic interactions  

NASA Astrophysics Data System (ADS)

In this paper, we delineate the consequences of electrokinetic interactions on the “coffee stain” effect, induced by the deposition of particles during drop evaporation. We consider evaporation of an electrolytic drop in contact with a charged substrate and probe the effects of electrical double layer formation at the drop-substrate interface on the dynamics of particles suspended inside the drop. We show that the simultaneous considerations of streaming potential and flow-actuation-mechanism-independent description of the evaporation flux and the depth average velocities result in an enhanced induced radial pressure gradient. As a result, the deposition speed of the particles in the disordered packing regime, occurring at the end of the lifetime of the drop [Marin , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.085502 107, 085502 (2011)], is greatly enhanced. This, in turn, is likely to signify an augmented degree of disordering in the evaporation-induced particle deposition.

Das, Siddhartha; Chakraborty, Suman; Mitra, Sushanta K.

2012-04-01

152

Effect of the fluorescent indicator calcein on Mg and Sr incorporation into foraminiferal calcite  

NASA Astrophysics Data System (ADS)

The development of particular analytical methods like laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) renders it possible to determine the composition of a single chamber of foraminifers tests. This is crucial in the investigation of benthic foraminifers since the growth of new chambers under laboratory conditions does not face the difficulties associated with experiments involving reproduction. The addition of chambers can be recognized by the incorporation of the fluorescent dye calcein. When added to the culture medium, previously formed chambers are not affected, and calcein is only incorporated in calcite that is formed in its presence. However, it has never been verified whether calcein affects the element incorporation into foraminiferal calcite. In order to investigate and quantify possible effects, specimens of the benthic foraminifer Ammonia tepida were cultured in the presence and absence of calcein (15°C, salinity 33), and Mg and Sr in newly formed chambers were analyzed with LA-ICP-MS. Magnesium concentrations of cross sections and longitudinal sections of foraminifera from the same experiment were also analyzed by electron microprobe measurements. Additionally, the impact of calcein on Mg and Sr incorporation in inorganically precipitated calcium carbonate crystals was quantified. Results show that presence of calcein does not impact the incorporation of Mg and Sr into biologically and inorganically precipitated calcium carbonate.

Dissard, Delphine; Nehrke, Gernot; Reichart, Gert Jan; Nouet, Julius; Bijma, Jelle

2009-11-01

153

Effects of Atomic Hydrogen on the Indium Incorporation in InGaN Grown by RF-Molecular Beam Epitaxy  

Microsoft Academic Search

We investigated the effect of atomic hydrogen(H) irradiation on the In incorporation in InGaN films grown by RF-molecular beam epitaxy (MBE)@. The molecular hydrogen (H2) and atomic H irradiation in InGaN growth by RF-MBE were found to enhance the In incorporation. The atomic H irradiation in InGaN growth increased the In incorporation with increasing H2 flow rate. The In incorporation

Yoshihiro Okamoto; Kazuya Takahashi; Hiromichi Nakamura; Yoshitaka Okada; Mitsuo Kawabe

2000-01-01

154

Dielectrophoretic trapping of nanoparticles with an electrokinetic nanoprobe.  

PubMed

A high aspect ratio 3D electrokinetic nanoprobe is used to trap polystyrene particles (200 nm), gold nanoshells (120 nm), and gold nanoparticles (mean diameter 35 nm) at low voltages (<1 V(rms)). The nanoprobe is fabricated using room temperature self-assembly methods, without the need for nanoresolution lithography. The nanoprobe (150-500 nm in diameter, 2-150 ?m in length) is mounted on the end of a glass micropipette, enabling user-specified positioning. The nanoprobe is one electrode within a point-and-plate configuration, with an indium-tin oxide cover slip serving as the planar electrode. The 3D structure of the nanoprobe enhances dielectrophoretic capture; further, electro-hydrodynamic flow enhances trapping, increasing the effective trapping region. Numerical simulations show low heating (1 K), even in biological media of moderate conductivity (1 S/m). PMID:23592407

Wood, Nicholas R; Wolsiefer, Amanda I; Cohn, Robert W; Williams, Stuart J

2013-06-11

155

Electrokinetic Hydrogen Generation from Liquid WaterMicrojets  

SciTech Connect

We describe a method for generating molecular hydrogen directly from the charge separation effected via rapid flow of liquid water through a metal orifice, wherein the input energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen production rates are shown to follow simple equations derived from the overlap of the fluid velocity gradient and the anisotropic charge distribution resulting from selective adsorption of hydroxide ions to the nozzle surface. Pressure-driven fluid flow shears away the charge balancing hydronium ions from the diffuse double layer and carries them out of the aperture. Downstream neutralization of the excess protons at a grounded target electrode produces gaseous hydrogen molecules. The hydrogen production efficiency is currently very low (ca. 10-6) for a single cylindrical jet, but can be improved with design changes.

Duffin, Andrew M.; Saykally, Richard J.

2007-05-31

156

ELECTROKINETIC DENSIFICATION OF COAL FINES IN WASTE PONDS  

SciTech Connect

The objective of this research is to demonstrate that electrokinetics can be used to remove colloidal coal and mineral particles from coal-washing ponds and lakes without the addition of chemical additives such as salts and polymeric flocculants. In this experimental and analytical study the authors elucidate the transport processes that control the rate of concentrated colloidal particle removal, demonstrate the process on a laboratory scale, and develop the scale-up laws needed to design commercial-scale processes. The authors are also addressing the fundamental problems associated with particle-particle interactions (electrical and hydrodynamic), the effects of particle concentration on the applied electric field, the electrochemical reactions that occur at the electrodes, and the prediction of power requirements.

E. James Davis

1998-05-01

157

Slip-enhanced electrokinetic energy conversion in nanofluidic channels  

NASA Astrophysics Data System (ADS)

We investigate theoretically the influence of hydrodynamic slip at the surface of a nanofluidic channel on the efficiency with which electrokinetic phenomena can be used to convert hydrostatic energy to electrical power. Slip is introduced by applying the Navier boundary condition to the pressure-driven and the electro-osmotic components of the fluid velocity. A strong enhancement in the efficiency is predicted for increasing slip length due to the resulting decrease in the fluidic impedance and increase in the streaming conductance. These effects are moderated by a decrease in the electrical impedance, which promotes dissipation. The maximum efficiency approaches 100% as the slip length diverges, and a potentially practical 40% efficiency is expected for a moderate 30 nm slip length in a 10 nm high channel. Recently reported slip lengths for carbon nanotube filters suggest that efficiencies above 70% and high power densities might be achieved in a graphitic system.

Ren, Yongqiang; Stein, Derek

2008-05-01

158

Nonlinear amplification in electrokinetic pumping in nanochannels in the presence of hydrophobic interactions.  

PubMed

We discover a nonlinear coupling between the hydrophobicity of a charged substrate and electrokinetic pumping in narrow fluidic confinements. Our analyses demonstrate that the effective electrokinetic transport in nanochannels may get massively amplified over a regime of bare surface potentials and may subsequently get attenuated beyond a threshold surface charging condition because of a complex interplay between reduced hydrodynamic resistance on account of the spontaneous inception of a less dense interfacial phase and ionic transport within the electrical double layer. We also show that the essential physics delineated by our mesoscopic model, when expressed in terms of a simple mathematical formula, agrees remarkably with that portrayed by molecular dynamics simulations. The nontrivial characteristics of the initial increment followed by a decrement of the effective zeta potential with a bare surface potential may open up the realm of hitherto-unexplored operating regimes of electrohydrodynamically actuated nanofluidic devices. PMID:23683203

Chakraborty, Suman; Chatterjee, Dipankar; Bakli, Chirodeep

2013-05-03

159

Column efficiency in micellar electrokinetic capillary chromatography  

SciTech Connect

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

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

1987-02-01

160

Ultrafast micropumping by biased alternating current electrokinetics  

NASA Astrophysics Data System (ADS)

This paper reports dramatic improvements in flow rate over conventional alternating current (ac) electrokinetic micropumps by exploiting asymmetry in electric potentials over the electrodes. A micropump consisting of a planar asymmetric electrode array was tested using ac signals with and without a direct current (dc) bias. All experiments were done at 100 kHz Vac. The pumping velocity is much faster with a dc voltage, in some cases by an order of magnitude, reaching a linear velocity of up to 2.5 mm/s with only 5.4 Vrms. The discovery presents an exciting opportunity for microfluidics. Future improvement can be anticipated with additional optimization.

Lian, Meng; Wu, Jie

2009-02-01

161

Understanding electrokinetics at the nanoscale: A perspective  

PubMed Central

Electrokinetics promises to be the microfluidic technique of choice for portable diagnostic chips and for nanofluidic molecular detectors. However, despite two centuries of research, our understanding of ion transport and electro-osmotic flow in and near nanoporous membranes, whose pores are natural nanochannels, remains woefully inadequate. This short exposition reviews the various ion-flux and hydrodynamic anomalies and speculates on their potential applications, particularly in the area of molecular sensing. In the process, we revisit several old disciplines, with some unsolved open questions, and we hope to create a new one.

Chang, Hsueh-Chia; Yossifon, Gilad

2009-01-01

162

Pilot Scale Ex-Situ Electrokinetic Remediation of Arsenic-Contaminated Soil  

Microsoft Academic Search

In this study, the effectiveness of ex situ electrokinetic remediation (EKR) in treating actual As-contaminated soil was evaluated at a pilot scale (1 m [W] × 1 m [L] × 1.5 m [H]). Ethylenediamine tetraacetic acid (EDTA) and sodium hydroxide as the catholyte and anolyte, respectively, were circulated to enhance the desorption of As. Two types of soil were collected from a real contaminated agricultural area: silty

Young-Hyun Kim; Do-Hyung Kim; Hong-Bae Jung; Bo-Ram Hwang; Sung-Hwan Ko; Kitae Baek

2012-01-01

163

Electrokinetically enhanced removal and degradation of nitrate in the subsurface using nanosized Pd\\/Fe slurry  

Microsoft Academic Search

The aim of this work was to evaluate the effectiveness of transporting the slurry of Pd\\/Fe bimetallic nanoparticles under an electric field in the subsurface for in situ removal and degradation of nitrate. To mimic the subsurface environment, a bench-scale horizontal column packed with nitrate-contaminated soil was treated by electrokinetic (EK) remediation coupled with the injection of nanosized Pd\\/Fe slurry.

Gordon C. C. Yang; Chih-Hsiung Hung; Hsiu-Chuan Tu

2008-01-01

164

Desorption characteristics of kaolin clay contaminated with zinc from electrokinetic soil processing  

Microsoft Academic Search

A number of bench scale laboratory column tests were carried out using a newly designed and developed electrokinetic cell\\u000a to investigate the fundamental behavior of zinc-spiked kaolin clay subjected to an electric field. Laboratory investigations\\u000a focused on (i) zinc migration by the combined effects of electromigration and electro-osmosis and (ii) the electrically induced\\u000a desorption characteristics of zinc-contaminated kaolin that occurred

Myung Ho Lee; Masashi Kamon; Soo Sam Kim; Jai-Young Lee; Ha Ik Chung

2007-01-01

165

Determination of vitamins in food based on supercritical fluid extraction prior to micellar electrokinetic capillary chromatographic analyses of individual vitamins  

Microsoft Academic Search

The separation of 14 water-soluble vitamins and vitamin cofactors was investigated by micellar electrokinetic capillary chromatography and diode array detection using sodium cholate as the micellar phase. The method was optimised with respect to the effect of buffer composition, capillary temperature and applied voltage resulting in separation of all compounds in about 25 min. With the current method it is

Steen Buskov; Peter Møller; Hilmer Sørensen; Jens Christian Sørensen; Susanne Sørensen

1998-01-01

166

Control of selectivity in micellar electrokinetic chromatography by modification of sodium dodecyl sulfate micelles with organic hydroxy compounds  

Microsoft Academic Search

Modification of micellar phases with solubilized solutes was examined to control the separation in micellar electrokinetic chromatography (MEKC). The addition of organic hydroxy compounds (1-hexanol, cyclohexanol and phenol) as modifiers to a micellar solution of sodium dodecyl sulfate specifically decreased the capacity factor of some aromatic analytes possessing hydrophilic functional groups. The effect of phenol was different in selectivity to

Shoichi Katsuta; Tohru Tsumura; Koichi Saitoh; Norio Teramae

1995-01-01

167

Role of stabilizers for treatment of clayey soil contaminated with phenanthrene through electrokinetic-Fenton process—Some experimental evidences  

Microsoft Academic Search

In electrokinetic-Fenton (EK-Fenton) process, the effects of the phosphate and SDS introduced from the anode chamber were investigated for the treatment of clay contaminated with phenanthrene. In tests with phosphate and SDS, the electrochemical phenomena were complicate trend compared to tests with HCl. These results resulted from complexation of phosphate with oxides and SDS, and then increase of dissolved SDS

Jung Hwan Kim; Soo Sam Kim; Ji Won Yang

2007-01-01

168

Effect of biosolid incorporation on arsenic distribution in Mollisol soils in central Chile  

Microsoft Academic Search

The effect of biosolid incorporation on arsenic distribution in Mollisol soils in central Chile was studied. Two soils were sequentially extracted for arsenic with a five-step method that accounts for the following arsenic forms: non-specifically adsorbed (F1), specifically adsorbed (F2), amorphous and poorly crystallized Fe and Al oxides (F3), well-crystallized Fe and Al oxides (F4) and residual (F5). The arsenic

Loreto Ascar; Inés Ahumada; Pablo Richter

2008-01-01

169

Overcoming chromatic-dispersion effects in fiber-wireless systems incorporating external modulators  

Microsoft Academic Search

We demonstrate two techniques to reduce the effects of fiber chromatic dispersion in fiber-wireless systems incorporating external modulators. We theoretically and experimentally show that the achievable link distance can be increased by varying the chirp parameter of the modulator to give large negative chirp using a dual-electrode Mach-Zehnder modulator (MZM) biased at quadrature. In addition, we show that dispersion can

Graham H. Smith; Dalma Novak; Zaheer Ahmed

1997-01-01

170

The effect of substitutional nitrogen incorporation on electron emission from CVD diamond  

Microsoft Academic Search

Nitrogen-doped CVD diamond films with varying substitutional nitrogen content were prepared. Relatively large amounts of substitutional nitrogen were successfully incorporated into the growing diamond without degrading the quality of the diamond when melamine (C 3H6N6) was used as a dopant precursor. It was found that substitutional nitrogen doping has a negligible effect on the electron emission properties of the CVD

W. B. Choi; R. Schlesser; A. T. Sowers; L. Bergman; R. J. Nemanich; Z. Sitar; J. J. Hren; J. J. Cuomo

1998-01-01

171

Incorporating many-body effects into modeling of semiconductor lasers and amplifiers  

SciTech Connect

Major many-body effects that are important for semiconductor laser modeling are summarized. The authors adopt a bottom-up approach to incorporate these many-body effects into a model for semiconductor lasers and amplifiers. The optical susceptibility function ({Chi}) computed from the semiconductor Bloch equations (SBEs) is approximated by a single Lorentzian, or a superposition of a few Lorentzians in the frequency domain. Their approach leads to a set of effective Bloch equations (EBEs). The authors compare this approach with the full microscopic SBEs for the case of pulse propagation. Good agreement between the two is obtained for pulse widths longer than tens of picoseconds.

Ning, C.Z.; Moloney, J.V.; Indik, R.A. [Univ. of Arizona, Tucson, AZ (United States)] [and others

1997-06-01

172

Electrokinetic Transport and Manipulation of Particles in Microfluidic Reservoirs  

NASA Astrophysics Data System (ADS)

Electrically controlled microfluidic devices have been proven to be very useful in manipulating both synthetic and biological particles in terms of efficiency, sensitivity, and simplicity. The success of these devices depends on a comprehensive understanding of electrokinetic particle transport in every part of their microchannels and reservoirs. In this talk we present an experimental and numerical study of the electrokinetic transport of spherical polystyrene beads in microfluidic reservoirs. We also demonstrate that polystyrene beads can be continuously focused, trapped, concentrated, and separated in microfluidic reservoirs. This diverse electrical control of particle transport in reservoirs is envisioned to open new possibilities for handling bioparticles in electrokinetic microfluidic systems.

Zhu, Junjie; Xuan, Xiangchun

2010-11-01

173

A method of producing electrokinetic power through forward osmosis  

NASA Astrophysics Data System (ADS)

A power generation method for harvesting renewable energy from salinity gradient is proposed. The principle of the proposed method encompasses forward osmosis (FO) and electrokinetic phenomena. With the salinity difference between draw and feed solutions, FO allows spontaneous water flow across a semi-permeable membrane. The flow of water is then directed through a porous medium where the electric power is generated from the electrokinetic streaming potential. With a glass porous medium and a commercial flat sheet FO membrane in a batch mode configuration, our lab scale experimental system has demonstrated the produced electrokinetic voltages of about several hundreds of milli-volts.

Cherng Hon, Kar; Zhao, Cunlu; Yang, Chun; Chay Low, Seow

2012-10-01

174

Factors affecting quantitative electrokinetic injections from submicroliter conductive vials in capillary electrophoresis.  

PubMed

The factors influencing quantitative electrokinetic injections in capillary electrophoresis for custom 340-nL, 10-microL, and 110-microL stainless steel sample vials have been investigated using a six-analyte mixture containing catecholamines and indolamines. Deleterious sample degradation is increased with smaller sampling vials, decreased capillary-electrode distances, and increased current passed during the injection. Zero-voltage injections from the smallest vials also demonstrate additional injection discrepancies when compared to larger-volume bulk solution injections. These effects are in addition to the electrokinetic bias and complicate the selection of appropriate internal standards. For nanoliter-volume conductive vials, the injection process creates new species and eliminates other electroactive species to such an extent that quantitation becomes problematic. PMID:10500488

Fuller, R R; Sweedler, J V

1999-09-15

175

Label-free attomolar detection of proteins using integrated nanoelectronic and electrokinetic devices.  

PubMed

High-sensitivity screening of biomarkers is critical to areas ranging from early disease detection and diagnosis to bioterrorism surveillance. Here the development of integrated nanoelectronic and electrokinetic devices for label-free attomolar detection of proteins is reported. Electrically addressable silicon nanowire field-effect transistors and electrodes for electrokinetic transport are integrated onto a common sensor chip platform, and the nanowire devices are subsequently functionalized with receptors for selective biomarker detection. Nanowire devices modified with monoclonal antibody for prostate specific antigen exhibit close to a 10(4) increase in sensitivity due to streaming dielectrophoresis and corresponding electrostatic contribution to the binding affinity after application of an AC electric field. The devices are also modified with receptors for cholera toxin subunit B and achieve a similar enhancement. These results show general applicability of this method, and could open up opportunities in early stage disease detection and the analysis of proteins from single cells. PMID:20209654

Gong, Jian-Ru

2010-04-23

176

A simple method for incorporating dynamic effects of intronic miRNA mediated regulation.  

PubMed

The importance of microRNA (miRNA) in modulating gene expression at the post-transcriptional level is well known. Such regulation has been shown to influence the dynamics of several regulatory networks including the cell cycle. In this study we incorporated regulatory effects of intronic miRNA into an existing mathematical model of the cell cycle through the use of an existing 'proxy' protein--the host protein. It was observed that the incorporation of intronic miRNA mediated regulation improved the performance of the model resulting in a closer match to experimental results. To test the universality of this approach we compared the effects of intronic miRNA mediated regulation and host protein mediated regulation. Further, we compared miRNA mediated and protein mediated positive and negative feedback regulations of the target protein. We found that the target protein profiles were predominantly similar. These observations show the applicability of our method for incorporating intronic miRNA mediated dynamic effects in models for regulation of gene expression. PMID:22699750

Gokhale, Sucheta; Hariharan, Manoj; Brahmachari, Samir K; Gadgil, Chetan

2012-06-15

177

Effect of ethanolamine on choline uptake and incorporation into phosphatidylcholine in human Y79 retinoblastoma cells.  

PubMed

The effect of physiological concentrations of ethanolamine on choline uptake and incorporation into phosphatidylcholine was investigated in human Y79 retinoblastoma cells, a multipotential, undifferentiated retinal cell line that has retained many neural characteristics. These cells have a high-affinity uptake system for choline, and the majority of the choline taken up was incorporated into phosphatidylcholine via the CDP-choline pathway. The presence of extracellular ethanolamine significantly decreased high-affinity choline uptake and, subsequently, the amount of choline incorporated into phosphatidylcholine. When 100 mumol/L ethanolamine was added, there was a decrease of about 8% in the phosphatidylcholine content. Ethanolamine had no effect on choline incorporation into phosphatidylcholine, however, once choline was taken up by the cell. The K'M and V'max for high-affinity choline uptake was increased from 0.93 to 9.74 microM and 19.60 to 79.25 pmol/min per mg protein, respectively, by the presence of 25 mumol/L ethanolamine. In contrast, 25 mumol/L choline had no effect on the kinetic parameters of high-affinity ethanolamine uptake. Therefore, the reduction in high-affinity choline transport by ethanolamine apparently is not simply due to competitive inhibition. 2,2-Dimethylethanolamine and 2-methylethanolamine both reduced choline uptake to a greater extent than ethanolamine. However, because these compounds exist at much lower concentrations than ethanolamine, they probably have little physiological influence. These results suggest that changes in ethanolamine concentration within the physiologic range can regulate the synthesis and content of phosphatidylcholine in a neural cell by influencing the uptake of choline. PMID:3559386

Yorek, M A; Dunlap, J A; Spector, A A; Ginsberg, B H

1986-11-01

178

Preliminary results of a UV-B effect incorporated GOSSYM model  

NASA Astrophysics Data System (ADS)

Field experiments and laboratory tests have shown multiple effects of enhanced ultraviolet-B (UV-B) radiation on cotton growth, development, and yield. Adverse effects include development of chlorotic and necrotic patches on leaves, reductions in total leaf area, plant height, photosynthesis, and yield. However, little work has been carried out to incorporate these experimental results into a simulation model and to estimate the effects of UV-B radiation under field conditions with varied environments and management practices. This study incorporates experimental results of UV-B effects on cotton crop into a cotton simulation model, GOSSYM, which is being used widely in various applications. In this work, first modules were modified to incorporate the effects of UV-B radiation on canopy photosynthesis, leaf area expansion, and stem and branch elongation. Then, the modified model was used to test the validity of model assumptions and algorithms on independent experimental data sets. Finally, preliminary studies were performed to simulate the effects of UV-B radiation in the field conditions at Stoneville, Mississippi using 30-year (1964-1993) climate data. Simulation results agreed well with experimental measurements, proving the validation of the model. Our results suggest that cotton lint yield declined with increased UV-B radiation. The reductions were 20% when UV-B irradiance was 12 kJ m-2 under irrigated conditions. Similar reductions in yield were predicted at lower UV-B radiation (11 kJ m-2) under rain-fed conditions. The modified model will be useful to simulate the impacts of UV-B radiation on cotton growth and yield under current and future climatic conditions and to suggest management options to mitigate the adverse effects.

Wang, Xinli; Gao, Wei; Reddy, K. Raja; Slusser, James; Xu, Min

2006-09-01

179

Hematite nanoparticle monolayers on mica electrokinetic characteristics.  

PubMed

Electrokinetic properties of ?-Fe(2)O(3) (hematite) nanoparticle monolayers on mica were thoroughly characterized using the streaming potential method. Hematite suspensions were obtained by acidic hydrolysis of ferric chloride. The average size of particles (hydrodynamic diameter), determined by dynamic light scattering (DLS) and AFM, was 22 nm (pH=5.5, I=10(-2)M). The hematite monolayers on mica were produced under diffusion-controlled transport from the suspensions of various bulk concentration. The monolayer coverage, quantitatively determined by AFM and SEM, was regulated within broad limits by adjusting the nanoparticle deposition time. This allowed one to uniquely express zeta potential of hematite monolayers, determined by the streaming potential measurements, in terms of the particle coverage. Such dependencies, obtained for various pH, were successfully interpreted in terms of the three-dimensional electrokinetic model. A universal calibrating graph was produced enabling one to determine hematite monolayer coverage from the measured value of the streaming potential. The influence of the ionic strength, varied between 10(-4) and 10(-2)M, on the zeta potential of hematite monolayers was also studied. Additionally, the stability of monolayers (desorption kinetics) was determined under in situ conditions using the streaming potential method. Our experimental data prove that it is feasible to produce uniform and stable hematite particle monolayers of well-controlled coverage. Such monolayers may find practical applications as universal substrates for protein immobilization (biosensors) and in electrocatalytic applications. PMID:22921408

Morga, Maria; Adamczyk, Zbigniew; O?wieja, Magdalena

2012-07-31

180

Effect of cobalt incorporation and lithium enrichment in lithium nickel manganese oxides.  

SciTech Connect

Candidate cathode materials of cobalt-incorporated and lithium-enriched Li{sub (1+x)}Ni{sub 0.25}Co{sub 0.15}Mn{sub 0.6}O{sub (2.175+x/2)} (x=0.225-0.65) have been prepared by a coprecipitation method and a solid-state reaction. We systematically investigated the effect of both cobalt presence and lithium concentration on the structure, physical properties, and electrochemical behavior of the studied samples. The electrochemical performance of the cobalt-containing compounds showed much less dependence on the variation in the lithium amounts compared to the cobalt-free counterpart. The study demonstrated that even with cobalt incorporation, proper lithium content is the key to desirable cathode materials with nanostructured primary particles that are indispensable to achieve high capacity and high rate capability and, therefore, both improved energy and power densities for lithium-ion batteries.

Deng, H.; Belharouak, I.; Wu, H.; Dambournet, D.; Amine, K. (Chemical Sciences and Engineering Division)

2010-05-10

181

Effect of silver incorporation in phase formation and band gap tuning of tungsten oxide thin films  

SciTech Connect

Silver incorporated tungsten oxide thin films are prepared by RF magnetron sputtering technique. The effect of silver incorporation in micro structure evolution, phase enhancement, band gap tuning and other optical properties are investigated using techniques such as x-ray diffraction, micro-Raman spectroscopy, atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and UV-Visible spectroscopy. Effect of silver addition in phase formation and band gap tuning of tungsten oxide thin films are investigated. It is found that the texturing and phase formation improves with enhancement in silver content. It is also found that as the silver incorporation enhances the thickness of the films increases at the same time the strain in the film decreases. Even without annealing the desired phase can be achieved by doping with silver. A broad band centered at the wavelength 437 nm is observed in the absorption spectra of tungsten oxide films of higher silver incorporation and this can be attributed to surface plasmon resonance of silver atoms present in the tungsten oxide matrix. The transmittance of the films is decreased with increase in silver content which can be due to increase in film thickness, enhancement of scattering, and absorption of light caused by the increase of grain size, surface roughness and porosity of films and enhanced absorption due to surface plasmon resonance of silver. It is found that silver can act as the seed for the growth of tungsten oxide grains and found that the grain size increases with silver content which in turn decreases the band gap of tungsten oxide from 3.14 eV to 2.70 eV.

Jolly Bose, R.; Kumar, R. Vinod; Sudheer, S. K.; Mahadevan Pillai, V. P. [Department of Optoelectronics, University of Kerala, Kariyavattom, Thiruvananthapuram, Kerala 695581 (India); Reddy, V. R.; Ganesan, V. [UGC - DAE Consortium for Scientific Research, Khandwa Road, Indore 452017, Madhyapradesh (India)

2012-12-01

182

SITE TECHNOLOGY CAPSULE; IN SITU ELECTROKINETIC EXTRACTION SYSTEM  

EPA Science Inventory

As a part of the Superfund Innovative Technology Evaluation (SITE) Program, the U.S. Environmental Protection Agency evaluated the In-Situ Electrokinetic Extraction (ISEE) system at Sandia National Laboratories, Albuquerque, New Mexico. The SITE demonstration results show ...

183

DEMONSTRATION BULLETIN: IN SITU ELECTROKINETIC EXTRACTION SYSTEM - SANDIA NATIONAL LABORATORIES  

EPA Science Inventory

Sandia National Laboratories (SNL) has developed an in situ soil remediation system that uses electrokinetic principles to remediate hexavalent chromium-contaminated unsaturated or partially saturated soils. The technology involves the in situ application of direct current to the...

184

Binary Electrokinetic Separation of Target DNA from Background DNA Primers.  

National Technical Information Service (NTIS)

This report contains the summary of LDRD project 91312, titled 'Binary Electrokinetic Separation of Target DNA from Background DNA Primers'. This work is the first product of a collaboration with Columbia University and the Northeast BioDefense Center of ...

C. D. James

2005-01-01

185

Macroscale description of electrokinetic flows at large zeta potentials: Nonlinear surface conduction  

NASA Astrophysics Data System (ADS)

For highly charged dielectric surfaces, the asymptotic structure underlying electrokinetic phenomena in the thin-double-layer limit reshuffles. The large counterion concentration near the surface, associated with the Boltzmann distribution in the diffuse layer, supports appreciable tangential fluxes appearing as effective surface currents in a macroscale description. Their inevitable nonuniformity gives rise in turn to comparable transverse currents, which, for logarithmically large zeta potentials, modify the electrokinetic transport in the electroneutral bulk. To date, this mechanism has been studied only using a weak-field linearization. We present here a generic thin-double-layer analysis of the electrokinetic transport about highly charged dielectric solids, which is not restricted to weak fields. We identify the counterion concentration amplification with the emergence of an internal boundary layer—within the diffuse part of the double layer—characterized by distinct scaling of ionic concentrations and electric field. In this multiscale description, surface conduction is conveniently localized within the internal layer. Our systematic scheme thus avoids the cumbersome procedure of retaining small asymptotic terms which change their magnitude at large zeta potentials. The electrokinetic transport predicted by the resulting macroscale model is inherently accompanied by bulk concentration polarization, which in turn results in nonlinear bulk transport. A novel fundamental subtlety associated with this intrinsic feature, overlooked in the weak-field approximation, has to do with the ambiguity of the “particle zeta potential” concept: In general, even uniformly charged surfaces are characterized by a nonuniform zeta-potential distribution. This impairs the need for a careful identification of the dimensionless number representing the transition to large zeta potentials.

Schnitzer, Ory; Yariv, Ehud

2012-08-01

186

Macroscale description of electrokinetic flows at large zeta potentials: nonlinear surface conduction.  

PubMed

For highly charged dielectric surfaces, the asymptotic structure underlying electrokinetic phenomena in the thin-double-layer limit reshuffles. The large counterion concentration near the surface, associated with the Boltzmann distribution in the diffuse layer, supports appreciable tangential fluxes appearing as effective surface currents in a macroscale description. Their inevitable nonuniformity gives rise in turn to comparable transverse currents, which, for logarithmically large zeta potentials, modify the electrokinetic transport in the electroneutral bulk. To date, this mechanism has been studied only using a weak-field linearization. We present here a generic thin-double-layer analysis of the electrokinetic transport about highly charged dielectric solids, which is not restricted to weak fields. We identify the counterion concentration amplification with the emergence of an internal boundary layer--within the diffuse part of the double layer--characterized by distinct scaling of ionic concentrations and electric field. In this multiscale description, surface conduction is conveniently localized within the internal layer. Our systematic scheme thus avoids the cumbersome procedure of retaining small asymptotic terms which change their magnitude at large zeta potentials. The electrokinetic transport predicted by the resulting macroscale model is inherently accompanied by bulk concentration polarization, which in turn results in nonlinear bulk transport. A novel fundamental subtlety associated with this intrinsic feature, overlooked in the weak-field approximation, has to do with the ambiguity of the "particle zeta potential" concept: In general, even uniformly charged surfaces are characterized by a nonuniform zeta-potential distribution. This impairs the need for a careful identification of the dimensionless number representing the transition to large zeta potentials. PMID:23005765

Schnitzer, Ory; Yariv, Ehud

2012-08-15

187

Inhibitory Effect of Solar Radiation on Thymidine and Leucine Incorporation by Freshwater and Marine Bacterioplankton  

PubMed Central

We studied the effect of solar radiation on the incorporation of [(sup3)H]thymidine ([(sup3)H]TdR) and [(sup14)C]leucine ([(sup14)C]Leu) by bacterioplankton in a high mountain lake and the northern Adriatic Sea. After short-term exposure (3 to 4 h) of natural bacterial assemblages to sunlight just beneath the surface, the rates of incorporation of [(sup3)H]TdR and [(sup14)C]Leu were reduced at both sites by up to (symbl)70% compared to those for the dark control. Within the solar UV radiation (290 to 400 nm), the inhibition was caused exclusively by UV-A radiation (320 to 400 nm). However, photosynthetically active radiation (PAR) (400 to 700 nm) contributed almost equally to this effect. Experiments with samples from the high mountain lake showed that at a depth of 2.5 m, the inhibition was caused almost exclusively by UV-A radiation. At a depth of 8.5 m, where chlorophyll a concentrations were higher than those in the upper water column, the rates of incorporation of [(sup3)H]TdR were higher in those samples exposed to full sunlight or to UV-A plus PAR than in the dark control. In laboratory experiments with artificial UV light, the incorporation of [(sup3)H]TdR and [(sup14)C]Leu by mixed bacterial lake cultures was also inhibited mainly by UV-A. In contrast, in the presence of the green alga Chlamydomonas geitleri at a chlorophyll a concentration of 2.5 (mu)g liter(sup-1), inhibition by UV radiation was significantly reduced. These results suggest that there may be complex interactions among UV radiation, heterotrophic bacteria, and phytoplankton and their release of extracellular organic carbon. Our findings indicate that the wavelengths which caused the strongest inhibition of TdR and Leu incorporation by bacterioplankton in the water column were in the UV-A range. However, it may be premature to extrapolate this effect to estimates of bacterial production before more precise information on how solar radiation affects the transport of TdR and Leu into the cell is obtained.

Sommaruga, R.; Obernosterer, I.; Herndl, G. J.; Psenner, R.

1997-01-01

188

Robust and high-resolution simulations of nonlinear electrokinetic processes in variable cross-section channels.  

PubMed

We present a model and an associated numerical scheme to simulate complex electrokinetic processes in channels with nonuniform cross-sectional area. We develop a quasi-1D model based on local cross-sectional area averaging of the equations describing unsteady, multispecies, electromigration-diffusion transport. Our approach uses techniques of lubrication theory to approximate electrokinetic flows in channels with arbitrary variations in cross-section; and we include chemical equilibrium calculations for weak electrolytes, Taylor-Aris type dispersion due of nonuniform bulk flow, and the effects of ionic strength on species mobility and on acid-base equilibrium constants. To solve the quasi-1D governing equations, we provide a dissipative finite volume scheme that adds numerical dissipation at selective locations to ensure both unconditional stability and high accuracy. We couple the numerical scheme with a novel adaptive grid refinement algorithm that further improves the accuracy of simulations by minimizing numerical dissipation. We benchmark our numerical scheme with existing numerical schemes by simulating nonlinear electrokinetic problems, including ITP and electromigration dispersion in CZE. Simulation results show that our approach yields fast, stable, and high-resolution solutions using an order of magnitude less grid points compared to the existing dissipative schemes. To highlight our model's capabilities, we demonstrate simulations that predict increase in detection sensitivity of ITP in converging cross-sectional area channels. We also show that our simulations of ITP in variable cross-sectional area channels have very good quantitative agreement with published experimental data. PMID:22996734

Bahga, Supreet S; Bercovici, Moran; Santiago, Juan G

2012-09-20

189

Temperature modeling and measurement of an electrokinetic separation chip  

Microsoft Academic Search

This work presents experimental [infrared (IR) thermography] and computational (finite element model) results of temperature\\u000a distributions of an electrokinetic separation chip. Thermal characteristics of both the electrolyte solution and the polymer\\u000a chip (SU-8) are taken into account in modeling temperature distributions during electrokinetic flow. Multiphysics and multiscale\\u000a simulation couples electrostatics, heat transfer, and fluid dynamics. The accompanying IR thermography is

Tiina Sikanen; Thomas Zwinger; Santeri Tuomikoski; Sami Franssila; Reijo Lehtiniemi; Carl-Magnus Fager; Tapio Kotiaho; Antti Pursula

2008-01-01

190

Effects of tumour necrosis factor-? on BrdU incorporation in cultured human enterocytes  

PubMed Central

Bromodeoxyuridine incorporation is a useful method for studying the pattern of DNA synthesis in proliferating cells. The distribution pattern of incorporated BrdU in villus enterocytes of duodenal explants was analysed after exposure to TNF? in organ culture. TNF? caused a consistent, low level uptake of BrdU in the portion of the nucleus close to the nuclear membrane, this pattern was absent from the control cultures. As these epithelial cells are terminally arrested in G0, the BrdU incorporation was thought not to be due to S phase DNA synthesis, but rather a response to the cytotoxic influence of TNF?. Microtitre plate proliferation assays of cell density and DNA synthesis were devised to study the effects of TNF? on confluent monolayers of the human foetal jejunal cell line I407 and the mouse fibrosarcoma cell line L929. Both cell lines showed a similar response to TNF?. Exposure to TNF? alone did not reduce cell numbers but did cause a significant increase in DNA synthesis (p < 0.05). When cycloheximtde was added in tandem with TNF? there was a significant reduction in cell number (p < 0.001) and level of DNA synthesis (p < 0.01) indicative of cell death. The DNA of cells exposed to TNF? and cycloheximide was fragmented when viewed on an electrophoresis gel. The results show that BrdU incorporation might be a good indicator of damage to the DNA of cells after cytotoxic insult. TNF? may be responsible for villus enterocyte damage in enteropathies such as coeliac disease and GVHR of the small bowel.

McDevitt, J.; Feighery, C.; O'Farrelly, C.; Martin, G.; Weir, D. G.

1995-01-01

191

Electrokinetics dependence on water-content in sand  

NASA Astrophysics Data System (ADS)

The electrokinetic potential results from the coupling between the water flow and the electrical current because of the presence of ions within water. This coupling is well described in fluid-saturated media, however its behavior under unsaturated flow conditions is still discussed. We propose here an experimental approach which can clearly describe streaming potential variations in unsaturated conditions. Several drainage experiments have been performed within a column filled with a clean sand. Streaming potential measurements are combined to capillary pressure and to water content measurements each 10 centimeter along the column. In order to model hydrodymanics during each experiment, we solve Richards equation in an inverse way which allows us to establish the relation between hydraulic conductivity and water content, and retention relation. The electrokinetic coefficient C shows a more complex behavior than it was previously reported and can not be fitted by the existing models. We show that the normalized electrokinetic coefficient increases first when water saturation decreases from 100% to about 80% - 95%, and then decreases as the water saturation decreases, whereas all previous works described a unifrom decrease of the normalized electrokinetic coefficient as water saturation decreases. We delimited two water saturation domains, and deduced two different empirical laws describing the evolution of the electrokinetic coefficient in unsaturated conditions. Finally, electrical potentials data from four different drainage experiments and hydrodynamics were jointly inversed, including electrical conductivity measurements in order to find a robust description of the electrokinetic coefficient behavior in unsaturated conditions.

Allègre, V.; Lehmann, F.; Jouniaux, L.; Sailhac, P.; Matthey, P.

2009-12-01

192

Electrokinetics of pH-regulated zwitterionic polyelectrolyte nanoparticles  

NASA Astrophysics Data System (ADS)

The electrokinetic behavior of pH-regulated, zwitterionic polyelectrolyte (PE) nanoparticles (NPs) in a general electrolyte solution containing multiple ionic species is investigated for the first time. The NPs considered are capable of simulating entities such as proteins, biomolecules, and synthetic polymers. The applicability of the model proposed is verified by the experimental data of succinoglycan nanoparticles available in the literature. We show that, in addition to their effective charge density, counterion condensation, double-layer polarization, and electro-osmotic flow of unbalanced counterions inside the double layer all significantly affect the electrophoretic behaviors of NPs. Our model successfully predicts many interesting electrophoretic behaviors, which qualitatively agree with experimental observations available in the literature. In contrast, because the effects of double-layer polarization and charge regulation are neglected, the existing theoretical models fail to explain the experimental results. The results gathered provide necessary information for the interpretation of relevant electrophoresis data in practice, and for nanofluidic applications such as biomimetic ion channels and nanopore-based sensing of single biomolecules.The electrokinetic behavior of pH-regulated, zwitterionic polyelectrolyte (PE) nanoparticles (NPs) in a general electrolyte solution containing multiple ionic species is investigated for the first time. The NPs considered are capable of simulating entities such as proteins, biomolecules, and synthetic polymers. The applicability of the model proposed is verified by the experimental data of succinoglycan nanoparticles available in the literature. We show that, in addition to their effective charge density, counterion condensation, double-layer polarization, and electro-osmotic flow of unbalanced counterions inside the double layer all significantly affect the electrophoretic behaviors of NPs. Our model successfully predicts many interesting electrophoretic behaviors, which qualitatively agree with experimental observations available in the literature. In contrast, because the effects of double-layer polarization and charge regulation are neglected, the existing theoretical models fail to explain the experimental results. The results gathered provide necessary information for the interpretation of relevant electrophoresis data in practice, and for nanofluidic applications such as biomimetic ion channels and nanopore-based sensing of single biomolecules. Electronic supplementary information (ESI) available: Detailed description of the effects of counterion condensation (CC) and double-layer polarization (DLP), the illustrated transformation of the perturbed flow and pressure fields in sub-problem two due to a CC effect, and the influence of the softness parameter of a PE NP on the scaled forces acting on it for the case of Fig. 10. See DOI: 10.1039/c2nr32277c

Yeh, Li-Hsien; Tai, Yi-Hsuan; Wang, Nan; Hsu, Jyh-Ping; Qian, Shizhi

2012-11-01

193

Effect of cobalt incorporation and lithium enrichment in lithium nickel manganese oxides  

Microsoft Academic Search

Candidate cathode materials of cobalt-incorporated and lithium-enriched Li{sub (1+x)}Ni{sub 0.25}Co{sub 0.15}Mn{sub 0.6}O{sub (2.175+x\\/2)} (x=0.225-0.65) have been prepared by a coprecipitation method and a solid-state reaction. We systematically investigated the effect of both cobalt presence and lithium concentration on the structure, physical properties, and electrochemical behavior of the studied samples. The electrochemical performance of the cobalt-containing compounds showed much less dependence

H. Deng; I. Belharouak; H. Wu; D. Dambournet; K. Amine

2010-01-01

194

Predicting skin permeability using liposome electrokinetic chromatography.  

PubMed

The potential of liposome electrokinetic chromatography (LEKC), which is applied to estimate compound penetration through the skin, was evaluated in this report. Quantitative retention-activity relationships (QRARs) were successfully constructed between the compound skin permeability coefficient (log K(p)) and the retention values (log k), as well as some calculated molecular descriptors by the stepwise regression method (R(2) = 0.902). Furthermore, the developed vector method was applied to compare the similarity between the reported lipophilicity measuring scales and compounds through the skin. Both results indicated that the transport of a compound into the liposomal membrane was more similar to its penetration through the skin than that into other systems including the octanol-water system. In a word, LEKC is a promising simple method to predict drug penetration through the skin. PMID:19173048

Wang, Yongjun; Sun, Jin; Liu, Hongzhuo; Liu, Jianfang; Zhang, Liqiang; Liu, Kai; He, Zhonggui

2008-10-24

195

Electrokinetic concentration of charged molecules  

DOEpatents

A method for separating and concentrating charged species from uncharged or neutral species regardless of size differential. The method uses reversible electric field induced retention of charged species, that can include molecules and molecular aggregates such as dimers, polymers, multimers, colloids, micelles, and liposomes, in volumes and on surfaces of porous materials. The retained charged species are subsequently quantitatively removed from the porous material by a pressure driven flow that passes through the retention volume and is independent of direction thus, a multi-directional flow field is not required. Uncharged species pass through the system unimpeded thus effecting a complete separation of charged and uncharged species and making possible concentration factors greater than 1000-fold.

Singh, Anup K. (Berkeley, CA); Neyer, David W. (Castro Valley, CA); Schoeniger, Joseph S. (Oakland, CA); Garguilo, Michael G. (Livermore, CA)

2002-01-01

196

Effects of ozone inhalation on polyamine metabolism and tritiated thymidine incorporation into DNA of rat lungs  

SciTech Connect

We examined the effects of low-level ozone (O3) inhalation on polyamine metabolism and tritiated thymidine (3H-TdR) incorporation into DNA in rat lungs. We have also compared the activities of ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, and glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of the pentose phosphate cycle and a typical marker of oxidant injury, to assess whether ODC can serve as a sensitive marker of O3 effects on the lung. We exposed 90-day-old male specific-pathogen-free Sprague-Dawley rats to either 0.45 +/- 0.05 ppm (882 +/- 98 micrograms/m3) O3 or filtered room air continuously for 3 days. After exposure, the rats were terminated and the lungs examined for enzyme activities, polyamine contents, DNA content, and 3H-TdR incorporation. We found that in exposed rats, the enzyme activities were significantly increased (p less than 0.05) relative to air controls. G6PD, 25%, ODC, 147%, and S-adenosylmethionine decarboxylase (AdoMet DC), 86%. Polyamine contents were also affected by O3; putrescine increased 80%, p less than 0.05, spermidine did not change, and spermine decreased 23%, p less than 0.05. 3H-TdR incorporation into DNA was significantly elevated, 155%, p less than 0.001, after O3 exposure while total lung DNA content remained unchanged. The concomitant and large increase in ODC activity (reflecting polyamine metabolism) and DNA labeling (reflecting DNA synthesis and/or repair), indicates a strong correlation between the two and suggests that polyamine metabolism may play an important role in the accelerated cell proliferation associated with O3 injury. Moreover, the greater increase in lung ODC activity compared to other enzymes offers a sensitive marker of the lung response to inhaled O3.

Elsayed, N.M.; Ellingson, A.S.; Tierney, D.F.; Mustafa, M.G. (Univ. of California, Los Angeles (USA))

1990-01-01

197

Novel electrokinetic approach reduces membrane fouling.  

PubMed

An innovative submerged membrane electro-bioreactor (SMEBR) was built to reduce membrane fouling through a combination of various electrokinetic processes. The objective of this research was to assess the capability of SMEBR to reduce fouling under different process conditions. At the bench scale level, using synthetic wastewater, membrane fouling of the SMEBR was compared to the fouling of a membrane bioreactor (MBR) in five runs. Different protein concentrations in the influent synthetic wastewater were selected to develop different membrane fouling potentials: high (240 mg/l), low (80 mg/l) and zero protein addition. The MBR and SMEBR were operated at a flux equal to the membrane critical flux in order to create high fouling rate conditions. Membrane fouling rate, expressed as the change in the trans-membrane pressure per day (kPa/d), decreased in the SMEBR 5.8 times (standard deviation (SD) = 2.4) for high protein wastewater, 5.1 times (SD = 2.4) for low protein content, and 1.3 times (SD = 0.7) for zero protein, when compared to the MBR. The supernatant concentrations of the soluble microbial products (SMP) were 195-210, 65-135 and less than 65 mg/l in respective experimental series. Following the bench scale study, membrane fouling was assessed in a pilot scale SMEBR, fed with raw un-clarified municipal wastewater, and operated under real-sewage variable quality conditions. The pilot SMEBR exhibited three times smaller membrane fouling rate than the MBR. It was concluded that electrokinetic processes generated by SMEBR led to a reduction of membrane fouling through: i) removal of soluble microbial products (mainly protein and polysaccharides) and colloidal organic materials; ii) change of the structure and morphology of the suspended solids due their conditioning by DC field. PMID:24011406

Ibeid, Sharif; Elektorowicz, Maria; Oleszkiewicz, Jan A

2013-08-22

198

Effect of biosolid incorporation on arsenic distribution in Mollisol soils in central Chile.  

PubMed

The effect of biosolid incorporation on arsenic distribution in Mollisol soils in central Chile was studied. Two soils were sequentially extracted for arsenic with a five-step method that accounts for the following arsenic forms: non-specifically adsorbed (F1), specifically adsorbed (F2), amorphous and poorly crystallized Fe and Al oxides (F3), well-crystallized Fe and Al oxides (F4) and residual (F5). The arsenic residual fraction was predominant in Pintué soil, whereas in Graneros soil, arsenic was mostly associated to amorphous Fe and Al oxides. Graneros soil exhibited a higher As(V) adsorbing capacity than Pintué soil, which relates to the higher clay and iron and aluminum oxides contents, confirming that these components participation is essential for the adsorption of this metalloid. Biosolid application at a rate of 100Mg ha(-1) caused an increase in arsenic bound to amorphous Fe and Al oxides and in the residual fraction, in Pintué soil. When Pintué soil was spiked with arsenic, aged for two months, and treated with biosolid (100Mg ha(-1)), the content of arsenic in the most labile fractions decreased, thus showing a favorable effect in its application to soils with few specific sites for arsenic adsorption. Arsenic speciation was carried out in the first two fractions of the sequential extraction procedure. As(V) was the main form in both fractions. Biosolid incorporation at a rate of 100Mg ha(-1) caused a significant increase in organic arsenic forms. PMID:17889255

Ascar, Loreto; Ahumada, Inés; Richter, Pablo

2007-09-21

199

The Effect of Titanium on Water Incorporation and Rheology of Olivine  

NASA Astrophysics Data System (ADS)

While there is general agreement that water significantly affects the physical properties of rocks, the water incorporation mechanism, particularly in olivine, is still under debate. Experiments with synthetic, polycrystalline olivine allow the controlled addition of trace elements as well as water. To this end we have conducted hotpressing and deformation experiments with solution-gelation derived Fo90 olivine doped with Ca and Ti. While the addition of Ca does not change the behavior relative to trace element-free solgel, trace amounts of titanium have a significant effect both on water incorporation and the rheology. Infrared spectroscopy suggests that from the presence of titanium water is retained in olivine during prolonged firing in a controlled atmosphere furnace at 1400C, while it is lost in Ti- free olivine. The experimental infrared spectra have the same two prominent absorption bands at 3572 and 3525 cm-1 as spectra of olivine from xenoliths. These bands indicate that water (hydrogen) is incorporated in a titanium-clinohumite type point defect. This defect is stable and significantly affects the physical properties of mantle rocks at low water contents. Diffusion creep rates are increased by about one order of magnitude in Ti-doped olivine, even if water contents are below detection levels. Experiments with different capsule materials also highlight their importance for water retention in the absence of buffers. The potential significance of the relationship between Ti abundance, water content and rheology for natural systems is shown for example by the correlation between Ti content and hydrogen in titanium clinohumite defects in cratonic xenoliths.

Faul, U.; Farla, R. J.; Fitz Gerald, J. D.; Jackson, I.

2011-12-01

200

Characterization of a silver-incorporated calcium phosphate film by RBS and its antimicrobial effects.  

PubMed

A thin calcium phosphate film was synthesized on both commercially pure Ti and Si wafers by electron beam evaporation of hydroxyapatite as an evaporant with simultaneous Ar ion beam bombardments. Silver was introduced into an ion-beam-assisted deposition of a calcium phosphate thin film for antimicrobial effect. The amount of incorporated silver ions was controlled by immersing calcium-phosphate-coated samples in different AgNO(3) concentrations, and Rutherford backscattering spectrometry (RBS) was employed to measure the amounts of substituted silver. The higher concentration of silver in the calcium phosphate film was more effective in reducing the bacteria of Escherichia coli ATCC 8739 and Streptococcus mutans OMZ 65 on contact with respect to controls. PMID:18458466

Han, I-H; Lee, I-S; Song, J-H; Lee, M-H; Park, J-C; Lee, G-H; Sun, X-D; Chung, S-M

2007-07-30

201

Electrokinetic demonstration at the unlined chromic acid pit  

SciTech Connect

Heavy-metal contaminated soils are a common problem at Department of Energy (DOE)-operated sites and privately owned facilities throughout the nation. One emerging technology which can remove heavy metals from soil in situ is electrokinetics. To conduct electrokinetic (EK) remediation, electrodes are implanted into the ground, and a direct current is imposed between the electrodes. Metal ions dissolved in the soil pore water migrate towards an electrode where they can be removed. The electrokinetic program at Sandia National Laboratories (SNL) has been focusing on electrokinetic remediation for unsaturated soils. A patent was awarded for an electrokinetic electrode system designed at SNL for applications to unsaturated soils. Current research described in this report details an electrokinetic remediation field demonstration of a chromium plume that resides in unsaturated soil beneath the SNL Chemical Waste Landfill (CWL). This report describes the processes, site investigation, operation and monitoring equipment, testing procedures, and extraction results of the electrokinetic demonstration. This demonstration successfully removed chromium contamination in the form of chromium(VI) from unsaturated soil at the field scale. After 2700 hours of operation, 600 grams of Cr(VI) was extracted from the soil beneath the SNL CWL in a series of thirteen tests. The contaminant was removed from soil which has moisture contents ranging from 2 to 12 weight percent. This demonstration was the first EK field trial to successfully remove contaminant ions from and soil at the field scale. Although the new patented electrode system was successful in removing an anionic contaminant (i.e., chromate) from unsaturated sandy soil, the electrode system was a prototype and has not been specifically engineered for commercialization. A redesign of the electrode system as indicated by the results of this research is suggested for future EK field trials.

Lindgren, E.R.; Hankins, M.G. [Sandia National Labs., Albuquerque, NM (United States); Mattson, E.D. [Salt-Unsat, Inc., Albuquerque, NM (United States); Duda, P.M. [Ktech Corp., Albuquerque, NM (United States)

1998-01-01

202

Incorporating partial shining effects in proton pencil-beam dose calculation  

NASA Astrophysics Data System (ADS)

A range modulator wheel (RMW) is an essential component in passively scattered proton therapy. We have observed that a proton beam spot may shine on multiple steps of the RMW. Proton dose calculation algorithms normally do not consider the partial shining effect, and thus overestimate the dose at the proximal shoulder of spread-out Bragg peak (SOBP) compared with the measurement. If the SOBP is adjusted to better fit the plateau region, the entrance dose is likely to be underestimated. In this work, we developed an algorithm that can be used to model this effect and to allow for dose calculations that better fit the measured SOBP. First, a set of apparent modulator weights was calculated without considering partial shining. Next, protons spilled from the accelerator reaching the modulator wheel were simplified as a circular spot of uniform intensity. A weight-splitting process was then performed to generate a set of effective modulator weights with the partial shining effect incorporated. The SOBPs of eight options, which are used to label different combinations of proton-beam energy and scattering devices, were calculated with the generated effective weights. Our algorithm fitted the measured SOBP at the proximal and entrance regions much better than the ones without considering partial shining effect for all SOBPs of the eight options. In a prostate patient, we found that dose calculation without considering partial shining effect underestimated the femoral head and skin dose.

Li, Yupeng; Zhang, Xiaodong; Fwu Lii, Ming; Sahoo, Narayan; Zhu, Ron X.; Gillin, Michael; Mohan, Radhe

2008-02-01

203

Effect of exercise on amino acid incorporation into myocardial contractile proteins  

Microsoft Academic Search

Amino acid incorporation into myocardial protein was studied in rats after an acute bout of exhaustive swimming. Hearts were removed at exhaustion, 1, 2, or 4 h of recovery and amino acid incorporation measured using [3H] phenylalanine in an isolated perfused heart preparation. Amino acid incorporation into total tissue protein was reduced 30% at exhaustion but returned to normal by

James R. Swartman; Paul B. Taylor; Betty Cook

1981-01-01

204

The Effect of Aluminum Oxide Incorporation on the Material And Electrical Properties of Hafnium Oxide on Ge  

SciTech Connect

Hafnium aluminate thin films were synthesized by atomic layer deposition (ALD) to assess the effect of aluminum oxide incorporation on the dielectric/Ge interfacial properties. In these Hf{sub x}Al{sub y}O{sub z} thin films, the Hf to Al cation ratio was effectively controlled by changing the ratio of hafnium oxide to aluminum oxide ALD cycles, while their short range order was changed upon increasing aluminum oxide incorporation, as observed by extended x-ray absorption fine structure analysis. The incorporation of aluminum oxide was shown to improve the electrical characteristics of hafnium oxide/Ge devices, including lower interface state densities and leakage current densities.

Sawkar-Mathur, M.; Perng, Y.-C.; Lu, J.; Blom, H.-O.; Bargar, J.; Chang, J.P.

2009-05-27

205

Is the societal approach wide enough to include relatives? Incorporating relatives' costs and effects in a cost-effectiveness analysis.  

PubMed

It is important for economic evaluations in healthcare to cover all relevant information. However, many existing evaluations fall short of this goal, as they fail to include all the costs and effects for the relatives of a disabled or sick individual. The objective of this study was to analyse how relatives' costs and effects could be measured, valued and incorporated into a cost-effectiveness analysis. In this article, we discuss the theories underlying cost-effectiveness analyses in the healthcare arena; the general conclusion is that it is hard to find theoretical arguments for excluding relatives' costs and effects if a societal perspective is used. We argue that the cost of informal care should be calculated according to the opportunity cost method. To capture relatives' effects, we construct a new term, the R-QALY weight, which is defined as the effect on relatives' QALY weight of being related to a disabled or sick individual. We examine methods for measuring, valuing and incorporating the R-QALY weights. One suggested method is to estimate R-QALYs and incorporate them together with the patient's QALY in the analysis. However, there is no well established method as yet that can create R-QALY weights. One difficulty with measuring R-QALY weights using existing instruments is that these instruments are rarely focused on relative-related aspects. Even if generic quality-of-life instruments do cover some aspects relevant to relatives and caregivers, they may miss important aspects and potential altruistic preferences. A further development and validation of the existing caregiving instruments used for eliciting utility weights would therefore be beneficial for this area, as would further studies on the use of time trade-off or Standard Gamble methods for valuing R-QALY weights. Another potential method is to use the contingent valuation method to find a monetary value for all the relatives' costs and effects. Because cost-effectiveness analyses are used for decision making, and this is often achieved by comparing different cost-effectiveness ratios, we argue that it is important to find ways of incorporating all relatives' costs and effects into the analysis. This may not be necessary for every analysis of every intervention, but for treatments where relatives' costs and effects are substantial there may be some associated influence on the cost-effectiveness ratio. PMID:20038191

Davidson, Thomas; Levin, Lars-Ake

2010-01-01

206

Incorporating uncertainity in regional ecological risk assessments: Ozone effects on southeastern USA forests  

SciTech Connect

Currently, assessments of how environmental stresses such as tropospheric ozone affect forests employ point estimates of factors such as ozone dose and species sensitivity. However, there is substantial regional heterogeneity in such factors. Hence, we have developed an approach for incorporating probabilistic analysis in estimating ecological risk at a regional scale. As an example, we model the effects of tropospheric ozone on the growth of loblolly pine stands in the southeastern USA. Our approach links software capable of automated Monte Carlo simulation to a Geographic Information System in order to assess the influence of uncertainty in factors such as ozone dose, soil moisture availability, and climate on regional patterns of loblolly growth rate. We demonstrate that this methodology may improve assessments of ecological risk by quantitating regional patterns in the influence of various factors on the predicted response of forests to ozone as well as identifying regions in which uncertainty in model predictions is the greatest.

Woodbury, P.B.; Smith, J.E.; Weinstein, D.A. [Boyce Thompson Institute for Plant Research, Ithaca, NY (United States)] [and others

1995-09-01

207

Injection of nutrients and TEAs in clayey soils using electrokinetics  

SciTech Connect

Bioremediation is a cost-effective and attractive technique for cleanup of organic contaminants in high-permeable soils. Difficulties in providing sufficient nutrients and terminal electron acceptors (TEAs) (e.g., nitrate and sulfate) to subsurface contaminant locations preclude its use for in situ biodegradation of organic contaminants in clayey soils. Electrokinetics is shown to be an effective means to inject necessary ionic nutrients and TEAs in clayey soils. Theoretical analysis and experimental results show that electromigration is a significant factor compared with advective transport rate of ions by electroosmosis. Negatively charged nutrients and TEAs could be injected via introducing them at the cathode and vice versa for positively charged ions. Results also indicate that the concentration achievable in the soil depends on the conductivity of the soil and the inlet concentration of the ion to be injected. The higher the soil conductivity and the inlet concentration the higher is the concentration of ionic nutrients and TEAs achievable in the soil. The pH conditions in the soil could be maintained within the range of approximately 6--9 by placing a calcium carbonate layer in the vicinity of the anode.

Thevanayagam, S. [State Univ. of New York, Buffalo, NY (United States). Dept. of Civil, Structural, and Environmental Engineering; Rishindran, T. [Terraprobe, Brampton, Ontario (Canada)

1998-04-01

208

Effects of ozone inhalation on polyamine metabolism and tritiated thymidine incorporation into DNA of rat lungs.  

PubMed

We examined the effects of low-level ozone (O3) inhalation on polyamine metabolism and tritiated thymidine (3H-TdR) incorporation into DNA in rat lungs. We have also compared the activities of ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, and glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of the pentose phosphate cycle and a typical marker of oxidant injury, to assess whether ODC can serve as a sensitive marker of O3 effects on the lung. We exposed 90-day-old male specific-pathogen-free Sprague-Dawley rats to either 0.45 +/- 0.05 ppm (882 +/- 98 micrograms/m3) O3 or filtered room air continuously for 3 days. After exposure, the rats were terminated and the lungs examined for enzyme activities, polyamine contents, DNA content, and 3H-TdR incorporation. We found that in exposed rats, the enzyme activities were significantly increased (p less than 0.05) relative to air controls. G6PD, 25%, ODC, 147%, and S-adenosylmethionine decarboxylase (AdoMet DC), 86%. Polyamine contents were also affected by O3; putrescine increased 80%, p less than 0.05, spermidine did not change, and spermine decreased 23%, p less than 0.05. 3H-TdR incorporation into DNA was significantly elevated, 155%, p less than 0.001, after O3 exposure while total lung DNA content remained unchanged. The concomitant and large increase in ODC activity (reflecting polyamine metabolism) and DNA labeling (reflecting DNA synthesis and/or repair), indicates a strong correlation between the two and suggests that polyamine metabolism may play an important role in the accelerated cell proliferation associated with O3 injury. Moreover, the greater increase in lung ODC activity compared to other enzymes offers a sensitive marker of the lung response to inhaled O3. We conclude that inhalation of O3 at levels similar to what may be encountered during some smog episodes can result in significant pulmonary biochemical alterations with a potential for long-term consequences. The possible association between ODC activity and DNA labeling may offer a new insight into the mechanism of tissue injury and repair. We also speculate that the changes in lung polyamines may reflect antioxidant and anti-inflammatory functions associated with the cellular defense against oxidant injury. PMID:2296762

Elsayed, N M; Ellingson, A S; Tierney, D F; Mustafa, M G

1990-01-01

209

Electrokinetic remediation of fluorine-contaminated soil: conditioning of anolyte.  

PubMed

The feasibility of anolyte conditioning on electrokinetic remediation of fluorine-contaminated soil was investigated with a field soil. The initial concentration of fluorine, pH and water content in the soil were 414mg/kg, 8.91 and 15%, respectively. Because the extraction of fluorine generally increased with the soil pH, the pH of the anode compartment was controlled by circulating strong alkaline solution to enhance the extraction of fluorine during electrokinetic remediation. The removal of fluorine increased with the concentration of the alkaline solution and applied current density and fluorine removed up to 75.6% within 14 days. Additionally, anolyte conditioning sharply increased the electro-osmotic flow, which enhanced the removal of fluorine in this study. In many respects, anolyte conditioning in electrokinetic remediation of fluorine-contaminated soil will be a promising technology. PMID:18462872

Kim, Do-Hyung; Jeon, Chil-Sung; Baek, Kitae; Ko, Sung-Hwan; Yang, Jung-Seok

2008-03-26

210

Methods for incorporating the effects of LWR coolant environments in pressure vessel and piping fatigue evaluations.  

SciTech Connect

This paper summarizes the work performed at Argonne National Laboratory on the fatigue of piping and pressure vessel steels in the coolant environments of light water reactors. The existing fatigue strain vs. life ({var_epsilon}-N) data were evaluated to establish the effects of various material and loading variables, such as steel type, strain range, strain rate, temperature, and dissolved-oxygen level in water, on the fatigue lives of these steels. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for carbon and low-alloy steels and austenitic stainless steels as a function of material, loading, and environment variables. Case studies of fatigue failures in nuclear power plants are presented, and the contribution of environmental effects to crack initiation is discussed. Methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the possible conservatism in the existing fatigue design curves of the ASME Code.

Chopra, O. K.; Shack, W. J.

2002-07-31

211

Microchip separations of neutral species via micellar electrokinetic capillary chromatography  

SciTech Connect

Micellar electrokinetic capillary chromatography (MECC) of three neutral coumarin dyes was performed on glass microchips. Manifolds of channels for analyte injection and separation were machined into one surface of the glass substrates using standard photolithographic, etching, and deposition techniques. Cover plates were then directly bonded over these channels to form capillary networks, with fluid flow in these networks controlled by varying the applied high-voltage potentials at the outlets. The separation capillary was 16.5 cm long for a serpentine channel chip and 1.3 cm long for a straight channel chip. Detection of analyte zones was accomplished by laser-induced fluorescence using the UV lines (nearly 350 nm) of an argon ion laser. At low applied electric field strengths, MECC analyses with on-chip injections gave high reproducibilities in peak areas and migration times (<1% for two of the three coumarins) and near constant separation efficiencies throughout the analysis. At high fields (>400 V/cm), analysis times were shorter, but separation efficiency decreased at later migration times. These peaks showed significant broadening, consistent with mass transfer effects. 14 refs., 6 figs., 2 tabs.

Moore, A.W. Jr.; Jacobson, S.C.; Ramsey, J.M. [Oak Ridge National Lab., TN (United States)

1995-11-15

212

Electrokinetic particle-electrode interactions at high frequencies  

NASA Astrophysics Data System (ADS)

We provide a macroscale description of electrokinetic particle-electrode interactions at high frequencies, where chemical reactions at the electrodes are negligible. Using a thin-double-layer approximation, our starting point is the set of macroscale equations governing the “bounded” configuration comprising of a particle suspended between two electrodes, wherein the electrodes are governed by a capacitive charging condition and the imposed voltage is expressed as an integral constraint. In the large-cell limit the bounded model is transformed into an effectively equivalent “unbounded” model describing the interaction between the particle and a single electrode, where the imposed-voltage condition is manifested in a uniform field at infinity together with a Robin-type condition applying at the electrode. This condition, together with the standard no-flux condition applying at the particle surface, leads to a linear problem governing the electric potential in the fluid domain in which the dimensionless frequency ? of the applied voltage appears as a governing parameter. In the high-frequency limit ??1 the flow is dominated by electro-osmotic slip at the particle surface, the contribution of electrode electro-osmosis being O(?-2) small. That simplification allows for a convenient analytical investigation of the prevailing case where the clearance between the particle and the adjacent electrode is small. Use of tangent-sphere coordinates allows to calculate the electric and flows fields as integral Hankel transforms. At large distances from the particle, along the electrode, both fields decay with the fourth power of distance.

Yariv, Ehud; Schnitzer, Ory

2013-01-01

213

Determination of food colorants by microemulsion electrokinetic chromatography.  

PubMed

A microemulsion electrokinetic chromatography (MEEKC) method was developed to analyze and detect eight food colorants (tartrazine, fast green FCF, brilliant blue FCF, allura red AC, indigo carmine, sunset yellow FCF, new coccine, and carminic acid), which are commonly used as food additives in various food products. The effects of sodium dodecyl sulfate (SDS) surfactant, organic modifier, cosurfactant, and oil were examined in order to optimize the separation. The amount of organic modifier (acetonitrile) and SDS surfactant were determined as apparent influences on the separation resolution while the type of oil and cosurfactant rarely affected the separation selectivity of the eight colorants. A highly efficient MEEKC separation method, where the eight colorants were separated with baseline resolution within 14 min, was achieved by using a microemulsion solution of pH 2.0 containing 3.31% SDS, 0.81% octane, 6.61% 1-butanol, and 10% acetonitrile. This optimal MEEKC method has a higher separation efficiency and similar detection limit when compared to conventional capillary electrophoresis (CE) method. Furthermore, a sample pretreatment is rarely needed when this MEEKC technique is used to analyze colorants in food products, whereas a suitable sample pretreatment (for example solid-phase extraction) has to be employed prior to CE separation in order to eliminate matrix interferences resulting from the constituents of the food sample. PMID:15669007

Huang, Hsi-Ya; Chuang, Chia-Ling; Chiu, Chen-Wen; Chung, Ming-Che

2005-02-01

214

Lycopene incorporation into egg yolk and effects on laying hen immune function.  

PubMed

Carotenoids are partially responsible for the colors of plants and when consumed by humans and animals are deposited into tissues (e.g., skin and egg yolk in laying hens) and may have health benefits. Because carotenoids are more available when consumed from egg yolk sources than vegetables, this research examined the ability of the laying hen to deposit dietary lycopene, a carotenoid that imparts red color in tomatoes, into the egg yolk and to investigate effects on immune function. All birds were housed in commercial cages, had ad libitum access to water, and were fed 100 g/bird per day. Experiment 1 consisted of 4 dietary concentrations of lycopene (0, 65, 257, and 650 mg of lycopene/kg of diet). High-performance liquid chromatography analysis confirmed that dietary lycopene was incorporated into egg yolks. Experiment 2 was a completely randomized design, with 3 concentrations of lycopene (0, 420, and 840 mg of lycopene/kg of diet) and 6 concentrations of alpha-tocopherol (0, 84, 164, 200, 284, and 364 mg of alpha-tocopherol/kg of diet). Egg yolk lycopene (P < 0.05) and vitamin E (P < 0.05) were increased with increasing dietary concentrations, whereas lutein and zeaxanthin concentrations remained constant. Immune responses (inflammatory, cutaneous basophil hypersensitivity, 1 degrees and 2 degrees antibody response) were induced but were not affected by dietary lycopene or vitamin E. These data indicate that lycopene can be incorporated into egg yolks, and at these dietary concentrations, alpha-tocopherol and lycopene may not affect the immune system of the laying hen. PMID:19038813

Olson, J B; Ward, N E; Koutsos, E A

2008-12-01

215

Epileptogenic drugs in a model nervous system: electrophysiological effects and incorporation into a phospholipid layer.  

PubMed

Mechanisms of epileptiform activity in a model nervous system (buccal ganglia of Helix pomatia) are presented. The ganglia contain the identified giant neurons B1 through B4. For epileptiform activity, pentylenetetrazol (1 mmol/L to 40 mmol/L) or etomidate (12.5 micromol/L to 500 micromol/L) were applied. Membrane pressure was measured using a Wilhelmy film balance. In electrophysiological experiments, both drugs induced several effects in all studied neurons: membrane resistance increased, down-stroke of action potentials declined, and all types of chemical synaptic potentials decreased (the latter concerns pentylenetetrazol only). The threshold was 1 mmol/L of pentylenetetrazol and 12.5 micromol/L of etomidate. Epileptiform potentials developed in neurons that had expressed the membrane mechanisms underlying pacemaker potentials. The threshold of this development was again 1 mmol/L of pentylenetetrazol and 12.5 micromol/L of etomidate. Epileptiform depolarizations appeared with 40 mmol/L of pentylenetetrazol and 500 micromol/L of etomidate. In biochemical experiments, both drugs incorporated into an artificial phospholipids membrane and increased pressure in the membrane. The threshold of pressure increase was 1 mmol/L of pentylenetetrazol and 12.5 micromol/L of etomidate. Pressure increased dose-dependently and was 69% and 63% above starting pressure of 10 mN/m with epileptogenic concentrations of pentylenetetrazol (40 mmol/L) and of etomidate (500 micromol/L), respectively. It is postulated that amphiphilic substances incorporate into cell membranes and increase intramembranous pressure, and that this disturbs several membrane processes mechanically and leads to epileptic depolarizations in pacemaker neurons. PMID:17049497

Altrup, Ulrich; Häder, Marc; Cáceres, José Luis Hernández; Malcharek, Stefan; Meyer, Michaela; Galla, Hans-Joachim

2006-10-17

216

Effects of thermal annealing and Si incorporation on bonding structure and fracture properties of diamond-like carbon films  

Microsoft Academic Search

The effects of thermal annealing and Si incorporation on the structure and properties of diamond-like carbon (DLC) films were investigated. As-deposited DLC film (DLC) and Si incorporated DLC film (Si-DLC), both with and without thermal annealing, were analyzed for bonding structure, residual stress, film thickness, elastic modulus and fracture properties using Raman spectroscopy, wafer curvature, nanoindentation, four-point bend fracture testing,

Heon Woong Choi; David M. Gage; Reinhold H. Dauskardt; Kwang-Ryeol Lee; Kyu Hwan Oh

2009-01-01

217

Micellar electrokinetic chromatography with acid labile surfactant.  

PubMed

We present a study of a degradable surfactant, sodium 4-[(2-methyl-2-undecyl-1,3-dioxolan-4-yl)methoxy]-1-propane sulfonate that is also known as an acid-labile surfactant (ALS). The performance of ALS as a pseudostationary phase is assessed and compared with established pseudostationary phases such as sodium dodecyl sulphate (SDS), volatile surfactants and polymeric micelles. ALS achieves separation efficiency of 100,000-145,000 theoretical plates and relative standard deviation (RSD) of electrophoretic mobility (n=5) of less than 3%. Retention factors with ALS are strongly correlated with those with SDS. This is shown by the R2=0.79 for all eleven analytes and an R2=0.992 for specifically the non-hydrogen bonding (NHB) analytes. However, ALS displays different selectivity than SDS for hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) solutes (R2 of 0.74 and 0.88, respectively). ALS is degraded to less surface active compounds in acidic solution. These less surface-active compounds are more compatible with the electrospray ionization mass spectrometry (ESI-MS). ALS has a half-life of 48 min at pH 4. ALS has the potential to couple micellar electrokinetic chromatography (MEKC) with the ESI-MS. ALS can be used as a pseudostationary phase for a high efficiency separation and later acid hydrolyzed to enable an ESI-MS analysis. PMID:22018715

Stanley, Bob; Lucy, Charles A

2011-09-29

218

Effect of 5-Fluoro-2?-Deoxyuridine on [3H]Thymidine Incorporation by Bacterioplankton in the Waters of Southwest Florida  

PubMed Central

The effect of 5-fluoro-2?-deoxyuridine (FdUrd) on [methyl-3H] thymidine incorporation by bacterioplankton populations in subtropical freshwater, estuarine, and oceanic environments was examined. In estuarine waters, intracellular isotope dilution was inhibited by FdUrd, which enabled us to estimate both intracellular and extracellular isotope dilution. In 2 of 10 cases, extracellular isotope dilution was significant. At low concentrations of [methyl-3H]thymidine or [6-3H]thymidine, FdUrd completely inhibited incorporation of radioactivity into protein and RNA. At high concentrations of [3H]thymidine, however, FdUrd had little effect on labeling patterns. The dihydrofolate reductase inhibitors amethopterin and trimethoprim had no effect on macromolecular labeling patterns. These results suggest that thymidylate synthase is not involved in nonspecific labeling and that FdUrd inhibits nonspecific labeling by blocking some other enzyme involved in thymidine catabolism. In oligotrophic oceanic and freshwater samples, FdUrd did not inhibit intracellular isotope dilution or [3H]thymidine labeling of protein and RNA, but caused some inhibition of [3H]thymidine incorporation into DNA. The ability of FdUrd to inhibit nonspecific macromolecular labeling during [3H]thymidine incorporation was significantly correlated (r = 0.84) with total thymidine incorporation (in picomoles per liter per hour). The results are discussed in terms of applications of FdUrd to routine bacterial production measurements and the general assumptions of [3H]thymidine incorporation.

Jeffrey, Wade H.; Paul, John H.

1988-01-01

219

Effect of Barley Flour Incorporation on the Instrumental Texture of Sponge Cake  

Microsoft Academic Search

Sponge cakes were prepared by incorporating barley flour (10, 20, 30, and 40%?w\\/w) into wheat flours. The sponge cakes were evaluated for their physical, chemical, nutritional, textural and sensory attributes. All the prepared products exhibited high in fiber, mineral and protein contents when compared with the 100%?wheat flour based product. Incorporation of barley flour improved the visual of the cake

Mahesh Gupta; Amarinder Singh Bawa; Anil Dutt Semwal

2009-01-01

220

Fast Myoglobin Detection Using Nanofluidic Electrokinetic Trapping Technique  

NASA Astrophysics Data System (ADS)

We report on the preconcentration-enhanced fast collection of myoglobin protein for the rapid detection of myocardial infarction. We use a one-dimensional micro/nanofluidic chip for electrokinetic preconcentration and demonstrate that the preconcentration factor of 1 ng/ml Alexa Fluor 488-labeled myoglobin is ˜1000 within 200 s, where the protein had a weak negative charge, thereby making it hard to perform electrokinetic trapping for neutral-like proteins. The potential feasibility with new assay strategies for use in a rapid immunoassay screening test for myocardial infarction is discussed.

Chun, DongWon; Kim, Sang Hui; Song, Hyungwan; Kwak, Seungmin; Kim, YooChan; Seok, HyunGwang; Lee, Sang-Myung; Lee, Jeong Hoon

2013-01-01

221

Incorporating haptic effects into three-dimensional virtual environments to train the hemiparetic upper extremity  

PubMed Central

Current neuroscience has identified several constructs to increase the effectiveness of upper extremity rehabilitation. One is the use of progressive, skill acquisition-oriented training. Another approach emphasizes the use of bilateral activities. Building on these principles, this paper describes the design and feasibility testing of a robotic / virtual environment system designed to train the arm of persons who have had strokes. The system provides a variety of assistance modes, scalable workspaces and hand-robot interfaces allowing persons with strokes to train multiple joints in three dimensions. The simulations utilize assistance algorithms that adjust task difficulty both online and offline in relation to subject performance. Several distinctive haptic effects have been incorporated into the simulations. An adaptive master-slave relationship between the unimpaired and impaired arm encourages active movement of the subject's hemiparetic arm during a bimanual task. Adaptive anti-gravity support and damping stabilize the arm during virtual reaching and placement tasks. An adaptive virtual spring provides assistance to complete the movement if the subject is unable to complete the task in time. Finally, haptically rendered virtual objects help to shape the movement trajectory during a virtual placement task. A proof of concept study demonstrated this system to be safe, feasible and worthy of further study.

Adamovich, Sergei; Fluet, Gerard G.; Merians, Alma S.; Mathai, Abraham; Qiu, Qinyin

2010-01-01

222

Separations of compounds of biological and environmental interest by micellar electrokinetic capillary chromatography  

SciTech Connect

Important criteria for the effective separation of compounds of biological or environmental interest by micellar electrokinetic capillary chromatography are discussed. Efficiencies of approximately 100,000 plates/meter are achieved in the separations of samples of derivatized amines, aflatoxins, and hydroxy aromatic compounds. Laser fluorometric detection is shown to be capable of detecting subpicogram injected quantities. Organic solvents such as 2-propanol and acetonitrile are added to the aqueous mobile phases normally used to improve the separation of hydrophobic compounds, impart different selectivities, and provide a means for gradient programming. Column diameter is found to influence efficiency, analysis time, and detection.

Balchunas, A.T.; Swaile, D.F.; Powell, A.C.; Sepaniak, M.J.

1988-10-01

223

Bile salt surfactants in micellar electrokinetic capillary chromatography: Application to hydrophobic molecule separations  

SciTech Connect

Bile Salt surfactants are used in the micellar electrokinetic capillary chromatography (MECC) separation of various hydrophobic compounds. The use of methanol in the mobile phase allows the separation of previously intractable compounds including polyaromatic hydrocarbons. The effects of methanol on critical micelle concentration is investigated for sodium dodecyl sulfate (SDS) and the bile salt sodium cholate. It is determined that the unique structure of the bile salt micelle is much more tolerant to the addition of organic solvents than SDS, thereby increasing the scope of applications of MECC to include hydrophobic compounds. 30 refs., 9 figs.

Cole, R.O.; Sepaniak, M.J. (Tennessee Univ., Knoxville, TN (USA). Dept. of Chemistry); Hinze, W.L. (Wake Forest Univ., Winston-Salem, NC (USA). Dept. of Chemistry); Gorse, J.; Oldiges, K. (Baldwin-Wallace Coll., Berea, OH (USA). Dept. of Chemistry)

1990-01-01

224

Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part II: Coupling between ion mobility, electrolysis, and acid–base equilibria  

Microsoft Academic Search

We present elements of electrolyte dynamics and electrochemistry relevant to microfluidic electrokinetics experiments. In Part I of this two-paper series, we presented a review and introduction to the fundamentals of acid-base chemistry. Here, we first summarize the coupling between acid-base equilibrium chemistry and electrophoretic mobilities of electrolytes, at both infinite and finite dilution. We then discuss the effects of electrode

Alexandre Persat; Matthew E. Sussx; Juan G. Santiago

2009-01-01

225

Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part I: Acid–base equilibria and pH buffers  

Microsoft Academic Search

We review fundamental and applied acid-base equilibrium chemistry useful to microfluidic electrokinetics. We present elements of acid-base equilibrium reactions and derive rules for pH calculation for simple buffers. We also present a general formulation to calculate pH of more complex, arbitrary mixtures of electrolytes, and discuss the effects of ionic strength and temperature on pH calculation. More practically, we offer

Alexandre Persat; Robert D. Chambers; Juan G. Santiago

2009-01-01

226

A Monte Carlo approach for incorporation of memory effect in switched gate bias experiments  

NASA Astrophysics Data System (ADS)

This article presents a Monte Carlo approach to simulate the dispersive transport of holes/H+ ions in silicon-dioxide using simplified formalism of continuous time random walk theory given by Montroll and Scher [E. W. Montroll and H. Scher, J. Stat. Phys. 9, 101 (1973); H. Scher and E. W. Montroll, Phys. Rev. B 12, 2455 (1975)]. It has been shown that the simulated results of this approach match quite well with the theoretical predictions for a value of dispersion coefficient, ?, =0.5 which validates our Monte Carlo simulator. We have used this simulator to resolve the memory effect observed by Saks et al. [N. S. Saks, D. B. Brown, and R. W. Rendell, IEEE Trans. Nucl. Sci. 38, 1130 (1991)] in their simulations of switched gate bias experiments in context with the hydrogen ion transport model for the buildup of radiation-induced interface states. We have accounted for the memory effect, which is related with the dwell time of an ion at the last hopping site just before field switching, by treating the first hop after field switching differently from all other hops. We have shown that the memory effect can be incorporated by modifying the value of ? only for the first hop after field switching depending on the dwell time at the last hopping site just before field switching. We have found that a logarithmic relationship between the two gives a very good match between the simulated and the experimental results of half-time (the time required to build 50% of saturated interface states) versus time of field switching, tswitch, relationship.

Subbaraman, Shaila; Sharma, D. K.; Vasi, J.; Das, A.

1998-03-01

227

First-principles study with charge effects of the incorporation of iodine in UO2  

NASA Astrophysics Data System (ADS)

The energetics of iodine atoms in uranium dioxide are calculated using Density Functional Theory. The so-called DFT + U method is applied with the U-ramping technique to circumvent the multiple minima problem that may arise in such calculations. The interstitial position as well as mono, di- and tri-vacancy sites are considered for the insertion of iodine. The possibility for these sites to be charged is explicitly taken into account. One observes that iodine tends to act like an acceptor thus favouring lower charge states for the sites filled with iodine compared to empty ones. The incorporation energies of the various sites exhibit a linear dependence with the position of the Fermi level in the gap of UO2. Solution energies as a function of stoichiometry deviations in UO2+x are deduced from a dilute defect model for the concentrations of available sites. The most favourable insertion sites for iodine are the di- and tri-vacancy sites for understoichiometric and overstoichiometric oxide respectively. For all stoichiometries, iodine is found to have positive solution energy, i.e. to be insoluble in UO2. A high concentration of iodine is shown to have a strong effect on the concentrations of self-defects and the position of the Fermi level.

Crocombette, Jean-Paul

2012-10-01

228

Effects of nisin-incorporated films on the microbiological and physicochemical quality of minimally processed mangoes.  

PubMed

The aim of this study is to examine the effects of nisin-incorporated cellulose films on the physicochemical and microbiological qualities of minimally processed mangoes. The use of antimicrobial films did not affect the physicochemical characteristics of mangoes and showed antimicrobial activity against Staphylococcus aureus, Listeria monocytogenes, Alicyclobacillus acidoterrestris and Bacillus cereus. The mango slices were inoculated with S. aureus and L. monocytogenes (10(7)CFU/g), and the viable cell numbers remained at 10(5) and 10(6)CFU/g, respectively, after 12days. In samples packed with antimicrobial films, the viable number of L. monocytogenes cells was reduced below the detection level after 4days. After 6days, a reduction of six log units was observed for S. aureus. In conclusion, nisin showed antimicrobial activity in mangoes without interfering with the organoleptic characteristics of the fruit. This result suggests that nisin could potentially be used in active packing to improve the safety of minimally processed mangoes. PMID:23673058

Barbosa, Ana Andréa Teixeira; Silva de Araújo, Hyrla Grazielle; Matos, Patrícia Nogueira; Carnelossi, Marcelo Augusto Guitierrez; Almeida de Castro, Alessandra

2013-04-11

229

Powerful tests for association on quantitative trait loci incorporating imprinting effects.  

PubMed

Genomic imprinting is an important epigenetic factor in complex traits study, and there has recently been considerable interest in association study for quantitative traits by incorporating imprinting. However, these methods need the assumptions of Hardy-Weinberg equilibrium or only use information from families with one child. In this paper, by taking imprinting into account and making no assumption about the distribution of the quantitative traits, we propose two novel classes of Q-C-TDTI(c) and Q-C-MAX(c) family-based association tests for quantitative traits. The tests flexibly accommodate family data with missing parental genotype and with multiple siblings. Q-C-TDTI(c) is derived from a two-stage analysis, where in the first stage Q-C-PAT(c) is applied to test for imprinting effects and in the second stage we select the most appropriate statistic among three transmission disequilibrium tests for association according to the finding from Q-C-PAT(c). Another proposed Q-C-MAX(c) approach takes the maximum of the three statistics. Compared with the existing alternative methods, the simulation results demonstrate that the two proposed tests are robust to population stratification and have better performance for testing association under various scenarios. Further, the powerful and versatile Q-C-TDTI(c) test is applied to analyze Framingham Heart Study data. PMID:23552672

Xia, Fan; Zhou, Ji-Yuan; Fung, Wing Kam

2013-04-04

230

Micellar electrokinetic capillary chromatography, high performance liquid chromatography and nuclear magnetic resonance—three orthogonal methods for characterization of critical drugs  

Microsoft Academic Search

Purity assessment of multicomponent drugs such as aminoglycoside antibiotics is still a challenge. For example, the high performance liquid chromatography (HPLC) method reported in the European Pharmacopoeia for gentamicin suffers from various disadvantages, i.e. missing robustness, long retention times and broad peaks. Previously an effective and robust micellar electrokinetic chromatography (MEKC) method has been described which is capable of separating

Ralph Deubner; Ulrike Holzgrabe

2004-01-01

231

The effectiveness of triclosan-incorporated plastic against bacteria on beef surfaces.  

PubMed

Triclosan is a nonionic, broad-spectrum, antimicrobial agent that has been incorporated into a variety of personal hygiene products, including hand soaps, deodorants, shower gels, mouthwashes, and toothpastes. In this study, plastic containing 1,500 ppm of triclosan was evaluated in plate overlay assays and meat experiments as a means of reducing populations of bacteria. Plate overlay assays indicated that the triclosan-incorporated plastic (TIP) inhibited the following organisms: Brochothrix thermosphacta ATCC 11509, Salmonella Typhimurium ATCC 14028, Staphylococcus aureus ATCC 12598, Bacillus subtilis ATCC 6051, Shigella flexneri ATCC 12022, Escherichia coli ATCC 25922, and several strains of E. coli O157:H7. In meat experiment 1, irradiated, lean beef surfaces inoculated with B. thermosphacta, Salmonella Typhimurium, E. coli O157:H7, or B. subtilis were covered with TIP, vacuum packaged, and stored for 24 h at 4 degrees C. Of the organisms tested, only populations of B. thermosphacta were slightly reduced. In meat experiment 2, prerigor beef surfaces were inoculated with E. coli O157: H7, Salmonella Typhimurium, or B. thermosphacta incubated at 4 degrees C for 24 h, wrapped in TIP or control plastic, vacuum packaged, and stored at 4 degrees C for up to 14 days. There was a slight reduction in the population of the organisms after initial application with TIP. However, bacterial populations following long-term, refrigerated (4 degrees C), vacuum-packaged storage up to 14 days were not statistically (P< or =0.05) or numerically different than controls. In meat experiment 3, even TIP-wrapped, vacuum-packaged beef samples that were temperature abused at 12 degrees C did not exhibit significant (P< or =0.05) or sustainable reductions after 14 days of 4 degrees C storage. Another study indicated that populations of E. coli O157:H7 or B. thermosphacta added directly to TIP were not affected after 2 h of refrigerated storage or that the antimicrobial activity could be extracted from the plastic. Additional experiments suggest that presence of fatty acids or adipose may diminish the antimicrobial activity of TIP on meat surfaces. This study demonstrates that while antimicrobial activity is detected against bacterial cultures in antimicrobial plate assays, plastic containing 1,500 ppm of triclosan does not effectively reduce bacterial populations on refrigerated, vacuum-packaged meat surfaces. PMID:10340667

Cutter, C N

1999-05-01

232

Micromolded polymer electrokinetic separation systems with variable volume sampling and integrated optical and conductivity detection  

NASA Astrophysics Data System (ADS)

The micromoulding of polymers has provided an ideal fabrication route for the construction of single-use integrated devices for electrokinetic microseparations. Our designs have incorporated injector geometry that allows variable injection volumes in microchannels controlled by a combination of programmed hydrodynamics and electrophoresis. The utility of the injection scheme is demonstrated for isotachophoresis separations. Further developments have lead to the incorporation of parallel opposed conductivity detection electrodes in two ways. Firstly, by the injection of conducting polymer into a pre-molded channel system and secondly through the molding of the polymer microchannels around electrodes pre-molded in conducting polymer. This has provided a potential rapid manufacturing route for low cost polymer separation devices. As well as integrated conductivity detection electrodes, simple optical elements have been incorporated into injection molded ITP devices to permit detection of the separated bands by optical means. A simple spherical lens was incorporated into the top section of the device which included the sample and buffer reservoirs. The lens was positioned directly above the conductivity detection electrodes, to permit simultaneous electrochemical and optical detection. The lens was used to perform visible absorption spectroscopy using an Ocean Optics spectrography and tungsten-halogen fiber-optic white light source.

Fielden, Peter R.; Baldock, Sara J.; Goddard, Nick J.; Morrison, Lee; Prest, Jeff E.; Treves Brown, Bernard J.; Zgraggen, Michele

2002-06-01

233

Characterization of Steels Using a Revised Kinematic Hardening Model Incorporating Bauschinger Effect.  

National Technical Information Service (NTIS)

A new variant of the nonlinear kinematic hardening model is proposed that accommodates both nonlinear and linear strain hardening during initial tensile loading and reduced elastic modulus during initial load reversal. It also incorporates the Bauschinger...

A. P. Parker E. Troiano J. H. Underwood C. Mossey

2002-01-01

234

Electro-kinetics of charged-sphere suspensions explored by integral low-angle super-heterodyne laser Doppler velocimetry  

NASA Astrophysics Data System (ADS)

We investigated the flow behaviour of colloidal charged-sphere suspensions using a newly designed integral low-angle super-heterodyne laser Doppler velocimetry instrument, which combines the advantages of several previous approaches. Sample conditions ranged from strong electrostatic interactions with pronounced short-range order to individual particles with no spatial correlations. The obtained power spectra correspond to diffusion broadened velocity distributions across the complete sample cross section. The excellent performance of the instrument is highlighted in detail by the example of electro-kinetic flow of suspensions in a closed cell of a rectangular cross section. We demonstrate the excellent performance of our approach with the example of electro-phoretic-electro-osmotic experiments, showing that a comprehensive flow characterization becomes possible by analysing the measured electro-kinetic mobilities, the flow-profile, an effective diffusion coefficient and the integrated scattering density. We briefly discuss present limitations, possible extensions and interesting applications in other fields.

Palberg, Thomas; Köller, Tetyana; Sieber, Bastian; Schweinfurth, Holger; Reiber, Holger; Nägele, Gerhard

2012-11-01

235

Effect of protein kinase C modulators on 14,15-epoxyeicosatrienoic acid incorporation into astroglial phospholipids.  

PubMed

Our previous studies have shown that 14,15-epoxyeicosatrienoic acid (14,15-EET) is a major product of arachidonic acid metabolism in astrocytes. The purpose of this study was to investigate cellular regulation of 14,15-EET incorporation, distribution, and metabolism in primary cultures of rat brain cortical astrocytes. Incorporation of 14,15-EET into astrocytes was lower (93,390 +/- 11,121 dpm/5 x 10(6) cells) than incorporation of 8,9-EET (226,500 +/- 5,567 dpm/5 x 10(6) cells) and arachidonic acid (321,600 +/- 1,200 dpm/5 x 10(6) cells). 14,15-EET was distributed in the order neutral lipids and free fatty acids (solvent front) > phosphatidylcholine (PC) > phosphatidylinositol (PI) > phosphatidylethanolamine. In contrast, 8,9-EET and arachidonic acid were exclusively incorporated into PC. During incubation, astroglial epoxide hydrolase selectively metabolized 14,15-EET, but not 8,9-EET, to its vic-diol. Although 4-phenylchalcone oxide, a potent inhibitor of epoxide hydrolase, completely inhibited 14,15-EET metabolism, a large amount of cell-incorporated radioactivity remained as free 14,15-EET. Long-term exposure of astrocytes to 4 beta-phorbol 12-myristate 13-acetate (4 beta-PMA) resulted in a time-dependent incorporation of 14,15-EET into PI but not in control cells exposed to 4 alpha-phorbol 12,13-didecanoate. PKC down-regulation completely inhibited epoxide hydrolase metabolism of 14,15-EET. Following recovery of down-regulated PKC, 1 week after treatment with 4 beta-PMA, astrocytes regained their normal pattern of low incorporation of 14,15-EET. Protein kinase C (PKC) inhibition by staurosporine enhanced 14,15-EET incorporation without affecting its metabolism to 14,15-dihydroxyeicosatrienoic acid.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7790878

Shivachar, A C; Willoughby, K A; Ellis, E F

1995-07-01

236

Effect of the Y955C Mutation on Mitochondrial DNA Polymerase Nucleotide Incorporation Efficiency and Fidelity  

PubMed Central

The human mitochondrial DNA polymerase (pol ?) is responsible for the replication of the mitochondrial genome. Mutation Y955C in the active site of pol ? results in early onset progressive external ophthalmoplegia, premature ovarian failure, and Parkinson’s disease. In single turnover kinetic studies, we show that the Y955C mutation resulted in a decrease in the maximum rate of polymerization and an increase in the Km for correct incorporation. The mutation decreased the specificity constant for correct incorporation of dGTP, TTP, and ATP to values of 1.5, 0.35, and 0.044 ?M?1s?1, respectively, representing reductions of 30-, 110- and 1300-fold relative to wild-type enzyme. The fidelity of incorporation was reduced 6- to 130-fold; largely due the significant decrease in the specificity constant for correct dATP:T incorporation. For example, kcat/Km for forming a TTP:T mismatch was decreased tenfold from 0.0002 to 0.00002 ?M?1s?1 by the Y955C mutant, but the 1300-fold slower incorporation of the correct dATP:T relative to wild-type led to a 130-fold lower fidelity. While correct incorporation of 8-oxo-dGTP was largely unchanged, incorporation of 8-oxo-dG with dA in the template strand was reduced 500-fold. These results support a role of Y955 in stabilizing A:T base pairs at the active site of pol ? and suggest that the severe clinical symptoms of patients with this mutation may be due, in part, to the reduced efficiency of dATP incorporation opposite T, and that the autosomal dominant phenotype may arise from the resulting higher mutation frequency.

Estep, Patricia A.; Johnson, Kenneth A.

2011-01-01

237

The effects of music therapy incorporated with applied behavior analysis verbal behavior approach for children with autism spectrum disorders.  

PubMed

This study compared a common form of Applied Behavior Analysis Verbal Behavior (ABA VB) approach and music incorporated with ABA VB method as part of developmental speech-language training in the speech production of children with Autism Spectrum Disorders (ASD). This study explored how the perception of musical patterns incorporated in ABA VB operants impacted the production of speech in children with ASD. Participants were 22 children with ASD, age range 3 to 5 years, who were verbal or pre verbal with presence of immediate echolalia. They were randomly assigned a set of target words for each of the 3 training conditions: (a) music incorporated ABA VB, (b) speech (ABA VB) and (c) no-training. Results showed both music and speech trainings were effective for production of the four ABA verbal operants; however, the difference between music and speech training was not statistically different. Results also indicated that music incorporated ABA VB training was most effective in echoic production, and speech training was most effective in tact production. Music can be incorporated into the ABA VB training method, and musical stimuli can be used as successfully as ABA VB speech training to enhance the functional verbal production in children with ASD. PMID:22506303

Lim, Hayoung A; Draper, Ellary

2011-01-01

238

[Effects of sub-micro emulsion composition on cellular disposition of incorporated lipophilic drug].  

PubMed

Objective: To investigate the effects of sub-micro emulsion composition on cellular uptake and disposition of incorporated lipophilic drug. Methods: Sub-micro emulsions containing 10 % oil, 1.2 % lecithin and 2.25 % glycerol were prepared, and the fluorescent agent coumarin 6 was used as a model drug. The effects of oil types, co-surfactants and cationic lipid on uptake and elimination kinetics of 6-coumarin in HeLa cells were studied. The uptake mechanism of sub-micro emulsions was further investigated. Results: Oil type and Tweens had no influence on the cellular uptake. Modifications of surfactants with Span series increased the cellular influx, among which Span 20 with hydrophilic-lipophilic balance (HLB) value of 8.6 was the best enhancer. The intracellular drug level reached up to (46.09 ±1.98)ng/?g protein which had significant difference with control group [(38.54 ±0.34)ng/?g protein]. The positively charged emulsions significantly increased the uptake rate constant and elimination rate constant which were 4 times and 1.5 times of those in anionic groups, respectively. The uptake enhancement was also observed in cationic emulsions, cellular concentrations at plateau were (42.73 ±0.84)ng/?g protein, which was about 3 times of that in anionic emulsions [(15.71 ±0.74)ng/?g protein], when extracellular drug concentration kept at 100 ng/ml. Cationic emulsions delivered the payload mainly by direct drug transfer to contacted cells, while the negative ones depended on both drug passive diffusion and clathrin-mediated endocytosis of drug containing oil droplets which accounted for 20% of the intracellular drug. Conclusion: Interfacial characteristic of sub-micro emulsions such as co-surfactants HLB as well as zeta potentials can influence lipophilic drug both in cellular uptake and elimination. PMID:24167133

Sun, Xiao-Yi; Xiang, Zhi-Qiang; Wu, Shuo; Lv, Yuan-Yuan; Liang, Wen-Quan

2013-09-01

239

Physicochemical soil-contaminant interactions during electrokinetic extraction  

Microsoft Academic Search

The feasibility of using electrokinetics to extract contaminants from soils has been established by bench-scale laboratory experiments and small-scale field tests. However, the physics and chemistry associated with the innovative remediation technology are not yet fully understood. Many physicochemical reactions occur simultaneously during the process. These reactions may enhance or reduce the cleanup efficiency of the process. They are particularly

Albert T. Yeung; Cheng-non Hsu; Rajendra M. Menon

1997-01-01

240

Micelles as pseudo-stationary phases in micellar electrokinetic chromatography  

Microsoft Academic Search

This review article describes some general comments on micellar electrokinetic chromatography (MEKC) from the viewpoint of pseudo-stationary phases and presents a compiled list of surfactants used for MEKC, prepared from published papers. We tried to give comments on some typical surfactants from the practical point of view.

P. G. Muijselaar; K. Otsuka; S. Terabe

1997-01-01

241

Extension of elution range in micellar electrokinetic capillary chromatography  

Microsoft Academic Search

The authors have successfully demonstrated one approach to extend elution range in micellar electrokinetic capillary chromatography (MECC). By silanating the surfaces of fused-silica capillaries with trimethylchlorosilane (TMCS) the authors lowered electroosmotic flow velocity and, more importantly, the net flow velocity of the micelle phase, thereby increasing elution range. This is accomplished at the expense of a loss in column efficiency

A. T. Balchunas; M. J. Sepaniak

1987-01-01

242

Microchip separations of neutral species via micellar electrokinetic capillary chromatography  

Microsoft Academic Search

Micellar electrokinetic capillary chromatography (MECC) of three neutral coumarin dyes was performed on glass microchips. Manifolds of channels for analyte injection and separation were machined into one surface of the glass substrates using standard photolithographic, etching, and deposition techniques. Cover plates were then directly bonded over these channels to form capillary networks, with fluid flow in these networks controlled by

Alvin W. Moore; Stephen C. Jacobson; J. Michael. Ramsey

1995-01-01

243

Recommendations for the determination of selectivity in micellar electrokinetic chromatography  

Microsoft Academic Search

A general approach for characterizing selectivity in micellar electrokinetic chromatography based on the solvation parameter model is recommended. Individual surfactants are characterized by their cohesion and capacity for polar interactions indicated as lone pair–lone pair electron attraction, dipole-type interactions, and hydrogen bond acidity and basicity. The statistical and chemical validity of the solvation parameter model requires that retention data are

Colin F Poole; Salwa K Poole; Michael H Abraham

1998-01-01

244

AC Electrokinetic Cell Separation on a Microfluidic Device  

Microsoft Academic Search

Rapid cell separation and collection is demonstrated through the integration of electrokinetic pumps, dielectrophoretic (DEP) traps and field driven valves into a well designed microfluidic channel loop. We present the ground-up design and analysis of this fully functional microfluidic device for the rapid separation and collection of live and dead yeast cells and malaria red blood cells (RBCs) at low

Zachary Gagnon; Hsueh-Chia Chang

2009-01-01

245

Micellar electrokinetic capillary chromatography of limonoid glucosides from citrus seeds  

Microsoft Academic Search

This report presents the results of an investigation into the application of micellar electrokinetic capillary chromatography (MECC) for the analysis of limonoid glucosides in a citrus seed extract. MECC based on sodium dodecyl sulphate (SDS) was used to provide highly efficient separations of the closely related structures. A phosphate-borate buffer containing SDS was used to optimize the separation conditions for

Vinayagum E. Moodley; Dulcie A. Mulholland; Mark W. Raynor

1995-01-01

246

Downhole Measurements of Electrokinetic Potential to Monitor Flow in Oilfields  

Microsoft Academic Search

Oil companies currently produce an average of three barrels of water for each barrel of oil, which is expensive and environmentally unfriendly: the produced water is contaminated and must be treated and disposed of carefully. Ideally, water production would be prevented or minimised by monitoring its movement within the reservoir and responding appropriately. We suggest that measurements of electrokinetic (or

J. Saunders; M. Jackson; C. Pain; E. Addiego-Guevara

2005-01-01

247

Enhanced electrokinetic remediation of contaminated manufactured gas plant soil  

Microsoft Academic Search

This paper evaluates different flushing agents to enhance the efficiency of electrokinetic remediation of a manufactured gas plant (MGP) soil contaminated with polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Because of high concentrations, PAHs were of environmental concern and required to be removed to acceptable levels. Four flushing agents, which included two surfactants (3% Tween 80, and 5% Igepal CA-720),

Krishna R. Reddy; Prasanth R. Ala; Saurabh Sharma; Surendra N. Kumar

2006-01-01

248

Electrokinetic remediation of anionic contaminants from unsaturated soils  

Microsoft Academic Search

Heavy-metal contamination of soil and groundwater is a widespread problem in the DOE weapons complex, and for the nation as a whole. Electrokinetic remediation is one possible technique for in situ removal of such contaminants from unsaturated soils. In previous studies at Sandia National Laboratories, the electromigration of chromate ions and anionic dye ions have been demonstrated. This paper reports

E. R. Lindgren; M. W. Kozak; E. D. Mattson

1992-01-01

249

Electrokinetic remediation of anionic contaminants from unsaturated soils.  

National Technical Information Service (NTIS)

Heavy-metal contamination of soil and groundwater is a widespread problem in the DOE weapons complex, and for the nation as a whole. Electrokinetic remediation is one possible technique for in situ removal of such contaminants from unsaturated soils. In p...

E. R. Lindgren M. W. Kozak E. D. Mattson

1992-01-01

250

Capillary electrokinetic separations: Influence of mobile phase composition on performance  

SciTech Connect

The composition of the mobile phase employed in capillary zone electrophoresis and the related technique, micellar electrokinetic capillary chromatography, is an important factor in determining separation performance. The influences of ionic salt, surfactant, and organic solvent mobile phase additives on separation efficiency, retention, and elution range are discussed and demonstrated. 23 refs., 2 figs., 2 tabs.

Sepaniak, M.J.; Swaile, D.F.; Powell, A.C.; Cole, R.O.

1990-01-01

251

The electrokinetic charging of polymers during capillary extrusion  

Microsoft Academic Search

A study has been made of the electrokinetic charging of polymers during capillary extrusion. The levels of charge in the extruded polymer are significant (similar 10?4 C m?3) and depend on the polymer impurity, capillary material, and on the temperature and rate of extrusion. The charging is believed to be due to the separation of the double layer formed at

D M Taylor; T J Lewis; T P T Williams

1974-01-01

252

Electrokinetic remediation of heavy metal-contaminated soils under reducing environments  

SciTech Connect

This paper describes the migration of hexavalent chromium, Cr(VI), nickel, Ni(II), and cadmium, Cd(II), in clayey soils that contain different reducing agents under an induced electric potential. Bench-scale electrokinetic experiments were conducted using two different clays, kaolin and glacial till, both with and without a reducing agent. The reducing agent used was either humic acid, ferrous iron, or sulfide, in a concentration of 1000 mg/kg. These soils were then spiked with Cr(VI), Ni(II), and Cd(II) in concentrations of 1000, 500 and 250 mg/kg, respectively, and tested under an induced electric potential of 1 VDC/cm for a duration of over 200 h. The reduction of chromium from Cr(VI) to Cr(III) occurred prior to electrokinetic treatment. The extent of this Cr(VI) reduction was found to be dependent on the type and amount of reducing agents present in the soil. The maximum reduction occurred in the presence of sulfides, while the minimum reduction occurred in the presence of humic acid. The concentration profiles in both soils following electrokinetic treatment showed that Cr(VI) migration was retarded significantly in the presence of sulfides due both to the reduction of Cr(VI) to Cr(III) as well as an increase in soil pH. This low migration of chromium is attributed to: (1) migration of Cr(VI) and the reduced Cr(III) fraction in opposite directions, (2) low Cr(III) migration due to adsorption and precipitation in high pH regions near the cathode in kaolin and throughout the glacial till, and (3) low Cr(VI) migration due to adsorption in the pH regions near the anode in both soils. Ni(II) and Cd(II) migrated towards the cathode in kaolin; however, the migration was significantly retarded in the presence of sulfides due to increased pH through most of the soil. Initial high pH conditions within the glacial till resulted in Ni(II) and Cd(II) precipitation, so the effects of reducing agents were inconsequential. Overall, this study demonstrated that the reducing agents, particularly sulfides, in soils may affect redox chemistry and soil pH, ultimately affecting the electrokinetic remediation process.

Reddy, K.R.; Chinthamreddy, S. (Univ. of Illinois, Chicago, IL (United States). Dept. of Civil and Materials Engineering)

1999-01-01

253

Effect of phospholipid acyl chain modulation on vitamin E incorporation into pulmonary artery endothelial cell membranes.  

PubMed

Incorporation of vitamin E (alpha-tocopherol) was measured in total membranes of pulmonary artery endothelial cells (PAEC) following treatment with eight synthetic phosphatidylethanolamines (PE) (Palmitoyloleoyl, 16:0-18:1 PE1; distearoyl, 18:0-18:0 PE2; dioleoyl, 18:1-18:1 PE3; stearoyl- linoleoyl, 18:0-18:2 PE4; dilinoleoyl, 18:2-18:2 PE5; stearoyl-arachidonyl, 18:0-20:4 PE6; diarachidonyl, 20:4-20:4 PE7; and stearoyl-docosahexenoyl, 18:0-22:6 PE8). Endogenous PE content of native membranes was 0.88 +/- 0.01 nmol/mg protein. Incorporation of PE irrespective of fatty acid content significantly (P < 0.02) increased the PE content of total membranes. Vitamin E incorporation in control membranes was 63 +/- 9 nmol/mg protein. Incorporation of vitamin E in PE1- to PE7-treated cells were significantly (P < 0.05) increased compared to controls and were comparable to each other. Vitamin E incorporation into PE8-treated cells was threefold greater (P < 0.001) than controls and twofold greater (P < 0.001) than PE1- to PE7-treated cells. Increased PE content results in increased vitamin E incorporation into PAEC membranes irrespective of the fatty acids present on the acyl chain, and maximal incorporation of vitamin E in PE8-treated cells may relate to the increased carbon chain length rather than to the degree of unsaturation at the sn2 position. PMID:8482731

Patel, J M; Abeles, A J; Block, E R

1993-05-01

254

Manure composition and incorporation effects on phosphorus in runoff following corn biomass removal.  

PubMed

Greater demand for corn ( L.) stover for bioenergy use may lead to increased corn production acreage with minimal surface residue cover, resulting in greater risk for soil erosion and phosphorus (P) losses in runoff. A rainfall simulation study was conducted to determine the effects of spring-applied dairy cow () manure (none, in-barn composted, and exterior walled-enclosure pit) with >200 g kg organic solids content following fall corn biomass removal with and without incorporation (chisel plow [CP] and no-till [NT]) on sediment and P in runoff. Runoff was collected from a 0.83-m area for 60 min following the onset of rainfall simulation (76 mm h), once in spring and once in fall. Runoff dissolved reactive P (DRP) and dissolved organic P (DOP) concentrations were positively correlated with manure P rate and were higher in NT compared with CP. Conversely, sediment and particulate P (PP) concentrations in runoff were inversely correlated with manure P rate (and manure solids) and were higher in CP compared with NT. Runoff volume where no manure was applied was higher in NT than in CP in spring but similar in fall. The addition of manure reduced runoff volumes by an average of 82% in NT and 42% in CP over spring and fall. Results from this study indicate that surface application of dairy manure with relatively high solids content may reduce sediment and PP losses in runoff without increasing the risk of increased DRP and DOP losses in the year of application where corn biomass is harvested. PMID:22031580

Yagüe, María R; Andraski, Todd W; Laboski, Carrie A M

255

Effects of low intensity pulsed ultrasound with and without increased cortical porosity on structural bone allograft incorporation  

Microsoft Academic Search

BACKGROUND: Though used for over a century, structural bone allografts suffer from a high rate of mechanical failure due to limited graft revitalization even after extended periods in vivo. Novel strategies that aim to improve graft incorporation are lacking but necessary to improve the long-term clinical outcome of patients receiving bone allografts. The current study evaluated the effect of low-intensity

Brandon G Santoni; Nicole Ehrhart; A Simon Turner; Donna L Wheeler

2008-01-01

256

Effect of biosolid incorporation to mollisol soils on Cr, Cu, Ni, Pb, and Zn fractionation, and relationship with their bioavailability  

Microsoft Academic Search

Biosolid application to soil may be a supply of nutrients and micronutrients but it may also accumulate toxic compounds which would be absorbed by crops and through them be incorporated to the trophic chain.The present study deals with the effect of biosolid application on Cr, Cu, Pb, Ni, and Zn in agricultural soils. The procedure used is sequential extraction so

Paula Guerra; Inés Ahumada; Adriana Carrasco

2007-01-01

257

Effect of trestatin, an amylase inhibitor, incorporated into bread, on glycemic responses in normal and diabetic patients?3  

Microsoft Academic Search

The effect of incorporating the pancreatic a- arnylase inhibitor trestatin into bread on postprandial plasma glucose and insulin excursions was tested in healthy volunteers and non-insulin-dependent diabetic patients. At both dose levels of trestatin (3 and 6 mg\\/75 g starch) the peak values of plasma glucose and insulin were reduced markedly (compared with pla- cebo) after the ingestion of 75

Alain Golay; Heinz Schneider; Evelyne Temler; Jean-Pierre Felber

258

Damage to the DNA of microorganisms from decay of incorporated ¹²I and the relationship of DNA damage to lethal effects  

Microsoft Academic Search

Iodine-125 decays by electron capture and is known to cause severe ; molecular damage to small organic molecules via vacancy cascades. In an ; examination of the biological effects of this decay mode we have labelled ; coliphages T1 and T4, as well as E. coli, with ¹²I-5-iododeoxyuridine, ; which is incorporated into DNA in place of thymidine. Labelled organisms

R. E. Krisch; F. Krasin; C. J. Sauri

1975-01-01

259

Evaluation of the effects of incorporation rate and depth of water-retentive amendment materials in sports turf constructions  

Microsoft Academic Search

The objective of the current laboratory study was to assess the effects of a number of amendment materials and the depth of incorporation on water retention. 300 mm rootzone profiles were established in 150 mm diameter plastic cylinders over a 50 mm gravel drainage layer. Five amendment materials (sphagnum peat, compost, zeolite, TerraCottem and Stockosorb) were mixed with a medium-coarse

Stanislav Hejduk; Stephen W. Baker; Christian A. Spring

2012-01-01

260

Polyion complex micelles incorporating poly (aryl benzyl ether) dendritic phthalocyanine: effective photosensitizers for enhanced photodynamic therapy  

NASA Astrophysics Data System (ADS)

A novel series of zinc (II) phthalocyanines bearing four poly (aryl benzyl ether) dendritic substituents with carboxylic acid functionalities (Gn-DPcZn (Gn=n-generation dendrimer, n=1-2)) loaded polymeric micelles (Gn-DPcZn/m) were formed. The time-dependent intracellular uptake of Gn-DPcZn in RPE cells increased as they were incorporated into micelles, but inversely correlated with the generation. The photocytoxity of Gn-DPcZn was improved by incorporation into polymeric micelles and increased with the generation.

Chen, Kuizhi; Yu, Ming; Zhang, Hong; Ma, Dongdong; Pang, Shujuan; Huang, Wei; Peng, Yiru

2012-12-01

261

Electrokinetic-enhanced bioaugmentation for remediation of chlorinated solvents contaminated clay  

PubMed Central

Successful bioremediation of contaminated soils is controlled by the ability to deliver bioremediation additives, such as bacteria and/or nutrients, to the contaminated zone. Because hydraulic advection is not practical for delivery in clays, electrokinetic (EK) injection is an alternative for efficient and uniform delivery of bioremediation additive into low-permeability soil and heterogeneous deposits. EK–enhanced bioaugmentation for remediation of clays contaminated with chlorinated solvents is evaluated. Dehalococcoides (Dhc) bacterial strain and lactate ions are uniformly injected in contaminated clay and complete dechlorination of chlorinated ethene is observed in laboratory experiments. The injected bacteria can survive, grow, and promote effective dechlorination under EK conditions and after EK application. The distribution of Dhc within the clay suggests that electrokinetic transport of Dhc is primarily driven by electroosmosis. In addition to biodegradation due to bioaugmentation of Dhc, an EK-driven transport of chlorinated ethenes is observed in the clay, which accelerates cleanup of chlorinated ethenes from the anode side. Compared with conventional advection-based delivery, EK injection is significantly more effective forestablis hingmicrobial reductive dechlorination capacity in low-permeability soils.

Mao, Xuhui; Wang, James; Ciblak, Ali; Cox, Evan E.; Riis, Charlotte; Terkelsen, Mads; Gent, David B.; Alshawabkeh, Akram N.

2012-01-01

262

Analysis of rotation-driven electrokinetic flow in microscale gap regions of rotating disk systems.  

PubMed

In the present study, a novel theoretical model is developed for the analysis of rotating thermal-fluid flow characteristics in the presence of electrokinetic effects in the microscale gap region between two parallel disks under specified electrostatic, rotational, and thermal boundary conditions. The major flow configuration considered is a rotor-stator disk system. Axisymmetric Navier-Stokes equations with consideration of electric body force stemming from streaming potential are employed in the momentum balance. Variations of the fluid viscosity and permittivity with the local fluid temperature are considered. Between two disks, the axial distribution of the electric potential is determined by the Poisson equation with the concentration distributions of positive and negative ions obtained from Nernst-Planck equations for convection-diffusion of the ions in the flow field. Effects of disk rotation and electrostatic and thermal conditions on the electrokinetic flow and thermal characteristics are investigated. The electrohydrodynamic mechanisms are addressed with an interpretation of the coupling nature of the electric and flow fields. Finally, solutions with electric potential determined by employing nonlinear or linearized Poisson-Boltzmann equation and/or invoking assumptions of constant properties are compared with the predictions of the present model for justification of various levels of approximation in solution of the electrothermal flow behaviors in rotating microfluidic systems. PMID:14654411

Soong, C Y; Wang, S H

2004-01-15

263

Comprehensive analysis of alternating current electrokinetics induced motion of colloidal particles in a three-dimensional microfluidic chip  

NASA Astrophysics Data System (ADS)

AC electrokinetics is becoming a strategic tool for lab-on-a-chip systems due to its versatility and its high level of integration. The ability to foreseen the behaviour of fluids and particles under non-uniform AC electric fields is important to allow new generations of devices. Though most of studies predicted motion of particles in co-planar electrodes configurations, we explore a pure 3-D AC electrokinetic effect that can open the way to enhance contact-less handling throughout the microchannel. By fabricating 3D microfluidic chips with a bi-layer electrodes configuration where electrodes are patterned on both sides of the microfluidic channel, we present a detailed study of the AC electrokinetic regimes that govern particles motion suspended in different host media subjected to a non-uniform AC electric field that spreads through the cross-section of the microchannel. We simulate and observe the motion of 1, 5, and 10 ?m polystyrene particles relative to the electrodes and provide an insight on the competition between electro-hydrodynamical forces and dielectrophoresis. We demonstrate that using relevant electrode designs combined with the appropriate applied AC potential, particles can be handled in 3-D in the micro-channel at a single or a collective level in several medium conductivities. Both numerical simulations and experimental results provide a useful basis for future biological applications.

Honegger, Thibault; Peyrade, David

2013-05-01

264

3D porous sol-gel matrix incorporated microdevice for effective large volume cell sample pretreatment.  

PubMed

In this study, we demonstrated an effective sample pretreatment microdevice that could perform the capture, purification, and release of pathogenic bacteria with a large-volume sample and at a high speed and high-capture yield. We integrated a sol-gel matrix into the microdevice which forms three-dimensional (3D) micropores for the cell solution to pass through and provides a large surface area for the immobilization of antibodies to capture the target Staphylococcus aureus (S. aureus) cells. The antibody was linked to the surface of the sol-gel via a photocleavable linker, allowing the cell-captured antibody moiety to be released by UV irradiation. In addition to the optimization of the antibody immobilization and UV cleavage processes, the cell-capture efficiency was maximized by controlling the sample flow rate with a pumping scheme (3 steps, 5 steps: 3 steps with one flutter step, 7 steps: 3 steps with two flutter steps) and the pumping time (100, 200, and 300 ms). A quantitative capture analysis was performed by targeting a specific gene site of protein A of S. aureus in real-time PCR (RT-PCR). While the 3-step process with an actuation time of 100 ms showed the fastest flow rate (1 mL sample processing time in 10 min), the pumping scheme with the 7-step process and the 300 ms actuation time revealed the highest cell-capture efficiency. A limit of detection study with the 7-step and the 300 ms pumping scheme demonstrated that 100 cells per 100 ?L were detected with a 70% yield, and even a single cell could be analyzed via on-chip sample preparation. Thus, our novel sol-gel based microdevice was proven more cost-effective, simple, and efficient in terms of its sample pretreatment ability compared to the use of a conventional 2D flat microdevice. This proposed sample pretreatment device can be further incorporated to an analytical functional unit to realize a micrototal analysis system (?TAS) with sample-in-answer-out capability in the fields of biomedical diagnostics, food safety testing, and environmental pollutant screening. PMID:22519648

Lee, Chan Joo; Jung, Jae Hwan; Seo, Tae Seok

2012-05-23

265

A predictive model for exemestane pharmacokinetics/pharmacodynamics incorporating the effect of food and formulation  

PubMed Central

Aims Exemestane (Aromasin®) is an irreversible aromatase inactivator used for the treatment of postmenopausal women with advanced breast cancer. The objective of this study was to evaluate the effect of formulation comparing a sugar-coated tablet (SCT) with a suspension and food on the pharmacokinetics (PK) and pharmacodynamics (PD) with respect to plasma estrone sulphate (E1S) concentrations of exemestane, using a PK/PD approach. Methods This was an open, three-period, randomized, crossover study. Twelve healthy postmenopausal women received single oral doses of 25 mg exemestane as a SCT after fasting or food and as a suspension after fasting. Exemestane and E1S concentrations were determined before and up to 14 days after drug administration. Population analysis was performed in two steps: (i) a compartmental PK model was selected incorporating the effect of food and formulation; (ii) conditional on the PK model, a PD model was developed employing indirect response models. Model selection was performed using standard statistical tests. Validation and assessment of the predictive capability of the selected model was performed using real test data sets obtained from the literature. Results A three-compartment model with first-order elimination rate best described exemestane disposition (k12 0.454, k21 0.158, k13 0.174, k31 0.016 and k 0.738 h?1). Absorption was described by a mono-exponential function [ka 2.3 (SCT after fasting), 1.1 (SCT after food) and 7.6 h?1 (suspension); lag time 0.2 h]. The PD model assumed that E1S plasma concentrations are determined by a zero-order synthesis rate (6.5 pg ml?1 h?1) and a first-order elimination constant (0.032 h?1). Exemestane inhibited E1S synthesis with a C50 value of 22.1 pg ml?1. The mean population estimates were used to simulate the administration of different doses of the drug (0.5, 1, 2.5, 5 and 25 mg day?1). The model predictions were in agreement with historical data. Conclusions Exemestane absorption is influenced by the formulation of the drug and by food, but its disposition is independent of both. PK differences do no translate into clinically important differences in the PD. The PK/PD model developed was able to predict successfully the response to different doses and administration schedules with respect to oestrogen suppression.

Valle, Marta; Di Salle, Enrico; Jannuzzo, Maria Gabriella; Poggesi, Italo; Rocchetti, Maurizio; Spinelli, Riccardo; Verotta, Davide

2005-01-01

266

Effect of Vanadium Incorporation on Electrochemical Performance of LiFePO(4) for Lithium-Ion Batteries  

Microsoft Academic Search

A series of LiFe{sub 1-x}VâPOâ\\/C samples have been successfully prepared using a two-step solid-state reaction route. The effect of vanadium incorporation on the performance of LiFePOâ has systematically been investigated with X-ray diffraction, Raman spectroscopy, charge\\/discharge measurements, and cyclic voltammetry tests. It is found that V incorporation significantly enhances the electrochemical performance of LiFePOâ. Particularly, the LiFePOâ\\/C sample with 5

L Zhang; G Liang; A Ignatov; M Croft; X Xiong; I Hung; Y Huang; X Hu; W Zhang; Y Peng

2011-01-01

267

Human serum albumin monolayers on mica: electrokinetic characteristics.  

PubMed

Adsorption of human serum albumin (HSA) on mica from 0.15 M NaCl solutions and various pH values was studied using in situ streaming potential measurements, AFM imaging, and XPS. The results obtained by the streaming potential were consistent with AFM measurements and theoretical predictions based on the random sequential adsorption model. This allowed one to determine both the kinetics of adsorption and the maximum coverage of HSA as a function of pH. At pH 3.5, the maximum coverage of HSA was 0.45 (which corresponds to 1.4 mg m(-2) neglecting hydration). This decreased monotonically with the increase in pH, attaining 0.30 (pH 5.1) and 0.25 (pH 7.4). At pH >10.5, the adsorption of HSA on mica was negligible. Further experimental studies performed for HSA monolayers of well-controlled coverage revealed their stability against pH cycling. It was found in these experiments that at pH <4 and >8 the electrokinetic properties of HSA monolayers approached the reference data pertinent to the bulk. However, for an intermediate pH range, deviations from the bulk reference data were observed, suggesting a dipolar (heterogeneous) charge distribution over adsorbed HSA molecules. This caused a slight shift in the isoelectric point of the monolayer determined to be 4.7 compared to the bulk value of 5.1. However, for the HSA coverage below 0.2, the effect of the substrate was significant, making the zeta potential more negative and shifting the apparent isoelectric point to more acidic values. It was suggested that these results obtained for planar and smooth interfaces could be used as reference data for interpreting albumin adsorption on colloid carrier particles. PMID:23057706

D?bkowska, Maria; Adamczyk, Zbigniew

2012-10-25

268

Electrokinetic particle-electrode interactions at high frequencies.  

PubMed

We provide a macroscale description of electrokinetic particle-electrode interactions at high frequencies, where chemical reactions at the electrodes are negligible. Using a thin-double-layer approximation, our starting point is the set of macroscale equations governing the "bounded" configuration comprising of a particle suspended between two electrodes, wherein the electrodes are governed by a capacitive charging condition and the imposed voltage is expressed as an integral constraint. In the large-cell limit the bounded model is transformed into an effectively equivalent "unbounded" model describing the interaction between the particle and a single electrode, where the imposed-voltage condition is manifested in a uniform field at infinity together with a Robin-type condition applying at the electrode. This condition, together with the standard no-flux condition applying at the particle surface, leads to a linear problem governing the electric potential in the fluid domain in which the dimensionless frequency ? of the applied voltage appears as a governing parameter. In the high-frequency limit ?>1 the flow is dominated by electro-osmotic slip at the particle surface, the contribution of electrode electro-osmosis being O(?(-2)) small. That simplification allows for a convenient analytical investigation of the prevailing case where the clearance between the particle and the adjacent electrode is small. Use of tangent-sphere coordinates allows to calculate the electric and flows fields as integral Hankel transforms. At large distances from the particle, along the electrode, both fields decay with the fourth power of distance. PMID:23410334

Yariv, Ehud; Schnitzer, Ory

2013-01-17

269

Lipase-catalyzed acidolysis of olive oil with capric acid: effect of water activity on incorporation and acyl migration.  

PubMed

Structured lipids were synthesized by acidolysis of olive oil and capric acid with an immobilized lipase (Lipozyme TL IM) from Thermomyces lanuginosus. The acidolysis reaction was carried out by incubating a 1:3 molar ratio of olive oil and capric acid under solvent-free reaction systems at 50 degrees C. The effect of water activity on the incorporation of capric acid was investigated, and the tested water activity range was between 0.22 and 0.80. Capric acid incorporation into triacylglycerols of the olive oil increased as the water activity increased, but the degree of acyl migration also increased. Also, the degree of acyl migration of modified olive oils with a similar degree of incorporation was investigated. High degrees of acyl migration occurred at water activities of 0.22 and 0.32 for the degree of incorporation of ca. 50 mol %. Only 8 h of reaction time was required to achieve incorporation of ca. 50 mol % at a water activity of 0.80, and the lowest acyl migration occurred at the same water activity. These results suggest that acyl migration can be efficiently minimized by a shorter reaction time at higher water activity. PMID:19728714

Oh, Ji-Eun; Lee, Kwang-Won; Park, Hye-Kyung; Kim, Jee-Young; Kwon, Kwang-Il; Kim, Jong-Wook; Kim, Hak-Ryul; Kim, In-Hwan

2009-10-14

270

Metabolic changes in deafferented central neurons of an insect, Acheta domesticus. I. Effects upon amino acid uptake and incorporation  

SciTech Connect

Chronic cercal deafferentation of the terminal ganglion in developing crickets (Acheta domesticus), which is known to suppress normal development of giant interneuron dendritic arborizations is shown here to reduce (/sup 3/H)leucine uptake and incorporation into ganglion proteins. Short term deafferentation of adult crickets, in contrast, does not depress amino acid uptake and incorporation significantly. Following unilateral long term deafferentation of the terminal ganglion, a comparison was made of the (/sup 3/H)leucine incorporation into primary dendritic processes and somata of deafferented and normally innervated medial giant interneurons (MGIs) within the same ganglion by means of quantitative autoradiography. Grain densities within dendrites of deafferented MGIs were significantly lower than in paired control MGIs' grain densities within somata of deafferented MGIs also were reduced, although the effects of deafferentation were less pronounced in somata than in target dendrites. These results imply a specific influence of afferent innervation on protein metabolism during growth and development of target postsynaptic elements.

Meyer, M.R.; Edwards, J.S.

1982-11-01

271

Effect of surface incorporation of broiler litter applied to no-till cotton on runoff quality  

Technology Transfer Automated Retrieval System (TEKTRAN)

A 2-yr field study was conducted on an Atwood silt loam (fine-silty, mixed, thermic Typic Paleudalfs) marginal upland soil to evaluate if incorporation of broiler litter into the soil surface in a no-till cotton affect runoff nutrient concentrations. The treatments consisted of 7.8 Mg ha-1 broiler l...

272

Recent NEPA effects on industrial development. [Better if EIS incorporated in decision-making process  

Microsoft Academic Search

If environmental impact statements are incorporated in the decision-making process, costly and time-consuming injunctions and challenges can be avoided. Energy companies generally approve of measures set out by the National Environmental Policy Act (NEPA) and accept their responsibility to comply with environmental laws. The courts have tended to recommend preliminary statements in preference to the risk of delays from hearings

1976-01-01

273

Saline or plant-incorporated methylmercury effects on distribution, demethylation, and blood parameters in rats  

Microsoft Academic Search

The influence of diet is recognized as a significant factor in the expression of toxicity. This applies particularly to toxins like methylmercury (MeHg) which are metabolically incorporated into growing food plants and biotransformed within the plant before ingestion. Methylmercury in this form may influence the early physiological and biochemical events which lead to development of toxicity. In a previous study,

M. Czuba; E. Komsta-Szumska; D. C. Mortimer; C. Champagne

1987-01-01

274

The effect of incorporating the lithological heterogeneity on the inverse modelling of a road embankment  

Microsoft Academic Search

Geomechanical models are indispensable for reliable design of engineering structures, such as road embankments and tunnels. These models are however far from perfect. Especially geological heterogeneity is still not adequately addressed. To overcome these problems, an inverse modelling technique can be implemented to incorporate observations into the deterministic model to improve the poorly known parameters and consequently the model results.

A. Hommels; F. Molenkamp; I. Kroon

275

The Perceived Effect of the Sociocultural Context on HIV/AIDS Identity Incorporation  

ERIC Educational Resources Information Center

Contexts influence the experience of disease. In this study, I examined how the sociocultural context (e.g., race, class, gender, and sexual orientation) affected the experience of living with HIV/AIDS and the incorporation of the HIV/AIDS identity into the self. I interviewed 36 individuals living with HIV/AIDS. Findings indicate that race,…

Baumgartner, Lisa M.

2012-01-01

276

The Perceived Effect of Time on HIV/AIDS Identity Incorporation  

ERIC Educational Resources Information Center

Individuals experience disease in a variety of contexts. In this study, I examined how the temporal context (e.g., historical time, social time, chronological age and the passage of time) affected the incorporation of the HIV/AIDS identity into the self. I used semi structured interviews to collect data from 36 individuals living with HIV/AIDS.…

Baumgartner, Lisa M.

2012-01-01

277

Effects of oxygen incorporation in GeSbTe films on electrical properties and thermal stability  

SciTech Connect

Oxygen incorporated Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) films were prepared by an ion beam sputtering deposition method. I-V curves of the oxygen incorporated GST active layer showed that the threshold voltage (V{sub th}) varied, depending on the level of incorporated oxygen. In the case of a GST film with an elevated oxygen content of 30.8%, the GST layer melted at 9.02 V due to the instability conferred by the high oxygen content. The formation of Ge-deficient hexagonal phases such as GeSb{sub 2}Te{sub 4} and Sb{sub 2}Te{sub 3} appear to be responsible for the V{sub th} variation. Impedance analyses indicated that the resistance in GST films with oxygen contents of 16.7% and 21.7% had different origins. Thermal desorption spectroscopy data indicate that moisture and hydrocarbons were more readily desorbed at higher oxygen content because the oxygen incorporated GST films are more hydrophilic than undoped GST films.

Jang, Moon Hyung; Park, Seung Jong; Lim, Dong Hyeok; Park, Sung Jin; Cho, Mann-Ho [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Cho, Seong Jin [Department of Physics, Kyungseong University, Pusan 608-736 (Korea, Republic of); Cho, Yoon Ho; Lee, Jong-Heun [Division of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

2010-03-01

278

Trauma management incorporating focused assessment with computed tomography in trauma (FACTT) - potential effect on survival  

PubMed Central

Background Immediate recognition of life-threatening conditions and injuries is the key to trauma management. To date, the impact of focused assessment with computed tomography in trauma (FACTT) has not been formally assessed. We aimed to find out whether the concept of using FACTT during primary trauma survey has a negative or positive effect on survival. Methods In a retrospective, multicentre study, we compared our time management and probability of survival (Ps) in major trauma patients who received FACTT during trauma resuscitation with the trauma registry of the German Trauma Society (DGU). FACTT is defined as whole-body computed tomography (WBCT) during primary trauma survey. We determined the probability of survival according to the Trauma and Injury Severity Score (TRISS), the Revised Injury Severity Classification score (RISC) and the standardized mortality ratio (SMR). Results We analysed 4.817 patients from the DGU database from 2002 until 2004, 160 (3.3%) were from our trauma centre at the Ludwig-Maximilians-University (LMU) and 4.657 (96.7%) from the DGU group. 73.2% were male with a mean age of 42.5 years, a mean ISS of 29.8. 96.2% had suffered from blunt trauma. Time from admission to FAST (focused assessment with sonography for trauma)(4.3 vs. 8.7 min), chest x-ray (8.1 vs. 16.0 min) and whole-body CT (20.7 vs. 36.6 min) was shorter at the LMU compared to the other trauma centres (p < 0.001). SMR calculated by TRISS was 0.74 (CI95% 0.40-1.08) for the LMU (p = 0.24) and 0.92 (CI95% 0.84-1.01) for the DGU group (p = 0.10). RISC methodology revealed a SMR of 0.69 (95%CI 0.47-0.92) for the LMU (p = 0.043) and 1.00 (95%CI 0.94-1.06) for the DGU group (p = 0.88). Conclusion Trauma management incorporating FACTT enhances a rapid response to life-threatening problems and enables a comprehensive assessment of the severity of each relevant injury. Due to its speed and accuracy, FACTT during primary trauma survey supports rapid decision-making and may increase survival.

2010-01-01

279

Effect of cholesterol or phospholipid incorporation on the chemical stability of the muramyldpeptide derivative B30MDP in mixed vesicles  

Microsoft Academic Search

Application of the muramyldipeptide derivative B30-MDP to liposomal vaccines will aid in the development of improved high immunogenicity vaccines. To give full play to the effectiveness of B30-MDP as a liposomal vaccine, it is important to evaluate the effect of cholesterol, dimyristoylphosphatidylcholine (DMPC) or distearoylphosphatidylcholine (DSPC) incorporation on the chemical stability of B30-MDP and physicochemical properties of B30-MDP\\/lipid mixed vesicles

S. Ando; H. Tsuge; T. Mayumi

1996-01-01

280

Development and validation of a microemulsion electrokinetic chromatography method for patulin quantification in commercial apple juice.  

PubMed

A microemulsion electrokinetic chromatography (MEECK) method for patulin (PAT) quantification in apple juice samples has been developed. The effects of several important factors such as co-surfactant type, concentration of surfactant, acetonitrile percentage in the microemulsion, and running voltage and temperature were investigated to determine the optimum conditions. They resulted to be: a background electrolyte (BGE) composed of 25mM of sodium tetraborate, SDS (2.16%w/w), ethanol (6.49%w/w), n-octanol (0.82%w/w) and 2%v/v acetonitrile; applied voltage of +15kV; and a capillary temperature of 35 degrees C. PAT was detected at 276nm. Quantification and detection limits (LOQ and LOD) in apple juice samples were 8.0microgL(-1) and 3.2microgL(-1), respectively. Patulin was extracted from apple juice using ethyl acetate with a mean recovery value of 75.3% (RSD=4.5). This method was applied to the measurement of patulin in twenty commercial apple juice samples obtained from different Danish supermarkets. The PAT apple juice mean and median levels obtained were 35.9 and 10.9microgL(-1), respectively. The comparison with a previously validated micellar electrokinetic chromatography (MEKC) method for PAT analysis showed the suitability of using MEEKC for this mycotoxin analysis. However, the expectations of obtaining a higher efficiency and thus lower limits of detection and quantitation when using MEEKC were not met. PMID:18430505

Murillo-Arbizu, M; González-Peñas, E; Hansen, S H; Amézqueta, S; Ostergaard, J

2008-03-08

281

Single cell antimicrobial susceptibility testing by confined microchannels and electrokinetic loading.  

PubMed

Multidrug-resistant pathogens are an emerging global health problem. In addition to the need of developing new antibiotics in the pipeline, the ability to rapidly determine the antibiotic resistance profiles of bacteria represents one of the most crucial steps toward the management of infectious diseases and the prevention of multidrug-resistant pathogens. Here, we report a single cell antimicrobial susceptibility testing (AST) approach for rapid determination of the antibiotic resistance of bacterial pathogens. By confining individual bacteria in gas permeable microchannels with dimensions comparable to a single bacterium, the antibiotic resistance of the bacteria can be monitored in real-time at the single cell level. To facilitate the dynamic loading of the bacteria into the confined microchannels for observation, AC electrokinetics is demonstrated for capturing bacteria to defined locations in high-conductivity AST buffer. The electrokinetic technique achieves a loading efficiency of about 75% with a negligible effect on the bacterial growth rate. To optimize the protocol for single cell AST, the bacterial growth rate of individual bacteria under different antibiotic conditions has been determined systematically. The applicability of single cell AST is demonstrated by the rapid determination of the antimicrobial resistant profiles of uropathogenic clinical isolates in Mueller-Hinton media and in urine. The antibiotic resistance profiles of bacteria can be determined in less than 1 h compared to days in standard culture-based AST techniques. PMID:23445209

Lu, Yi; Gao, Jian; Zhang, Donna D; Gau, Vincent; Liao, Joseph C; Wong, Pak Kin

2013-02-27

282

Determination of phthalate esters in soil by microemulsion electrokinetic chromatography coupled with accelerated solvent extraction.  

PubMed

A novel method using microemulsion electrokinetic chromatography combining accelerated solvent extraction was developed for quantitative analysis of six phthalate esters (PAEs) including dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, as well as dioctyl phthalate. The effect of each individual component within the microemulsions, i.e. oil phase, surfactant and co-surfactant on resolution of the analytes was systematically studied. Baseline separation of six PAEs was achieved within 26?min by using the microemulsion buffer containing a 60?mmol/L borate buffer at pH 9.0, 0.5% v/v n-octane as oil droplets, 100?mmol/L sodium cholate as surfactant and 5.0% v/v 1-butanol as co-surfactant. The purposed accelerated solvent extraction-microemulsion electrokinetic chromatography method was successfully applied to the determination of trace amount of PAEs in soil samples collected from three different fields in areas of Fujian Province and the contents of dimethyl phthalate, diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate and dioctyl phthalate were 0.63-0.68, 0.32-0.63, 2.53-3.96, 0-1.75, 7.32-11.7 and 0-3.46mg/kg, respectively. It was validated that the results were consistent with those obtained by GC-MS method. PMID:21077130

Lin, Zian; Zhang, Jianhua; Cui, Huimin; Zhang, Lan; Chen, Guonan

2010-12-01

283

Fluorapatite surface composition in aqueous solution deduced from potentiometric, electrokinetic, and solubility measurements, and spectroscopic observations  

NASA Astrophysics Data System (ADS)

The surface chemistry of fluorapatite in aqueous solution was investigated using electrokinetic techniques, potentiometric titrations, solubility measurements, and attenuated total reflection infrared spectroscopy. All methods indicate the formation of Ca/F depleted, P enriched altered layer via exchange reactions between H + and Ca 2+, and OH - and F - at the fluorapatite (FAP) surface. Observations suggest that this leached layer has a di-calcium phosphate (CaHPO 4) composition and that it controls the apparent solubility of FAP. Electrokinetic measurements yield an iso-electric point value of 1 ± 0.5 consistent with a negatively charged FAP surface at pH > 1. In contrast, surface titrations give an apparent pH of point of zero charge of ˜7.7, consistent with a positively charged surface at pH < 7.7. These differences are shown to stem from proton consumption by both proton exchange and dissolution reactions at the FAP surface. After taking account for these effects, FAP surface charge is shown to be negative to at least pH 4 by surface titration analysis.

Chaïrat, Claire; Oelkers, Eric H.; Schott, Jacques; Lartigue, Jean-Eric

2007-12-01

284

Enhanced on-chip SERS based biomolecular detection using electrokinetically active microwells.  

PubMed

Here we present a novel microfluidic technique for on-chip surface enhanced Raman spectroscopy (SERS) based biomolecular detection, exploiting the use of electrokinetically active microwells. Briefly, the chip comprises of a series of microfluidic channels containing embedded microwells that, when electrically actuated, either locally attract or repulse species from solution through a combination of electrokinetic effects. We demonstrate that the approach combines the advantages of existing homogeneous (solution phase) and heterogeneous (surface phase) on-chip techniques by enabling active mixing to enhance the rate of binding between the SERS enhancers and the biomolecular targets as well as rapid concentration of the product for surface phase optical interrogation. This paper describes the chip design and fabrication procedure, experimental results illustrating the optimal conditions for our concentration and mixing processes, and a numerical analysis of the flow pattern. To demonstrate the usefulness of the device we apply it to the quantitative detection of nucleic acid sequences associated with Dengue virus serotype 2. We report a limit of detection for Dengue sequences of 30 pM and show excellent specificity against other serotypes. PMID:19156293

Huh, Yun Suk; Chung, Aram J; Cordovez, Bernardo; Erickson, David

2008-11-12

285

Application of electrokinetics for stimulating microbial clean-up of contaminated soils  

NASA Astrophysics Data System (ADS)

Given sufficient time there are few synthetic compounds that can resist microbial degradation, a fact exploited in environmental clean-up. Despite this the performance of micro-organisms in remedial technologies is often sub-optimal. There are many reasons for the failure of indigenous microbial communities to reduce contaminant concentrations, including issues of bioavailability and the inability of the contaminants to switch on genes (catabolic) responsible for contaminant degradation. Even if the presence of the required catabolic genes is confirmed, there continues to be a significant need to develop procedures to stimulate their activity. We have investigated the potential of soil electrokinetics (3-4 A m-2) to stimulate microbial degradation of organic pollutants and move the soil contaminants relative to the degradative microorganisms, so increasing contact between the two components. Using soils contaminated with pentachlorophenol as our model laboratory system, we have demonstrated that the technique is effective at causing gross and controlled movement of PCP through soils at the laboratory-scale. It can also stimulate rates (up to 25% over that of the control) by which introduced bacteria degrade the contaminant. The additional potential benefits of electrokinetics in regard to stimulating microbial activity and soil clean-up will be discussed.

Thompson, I.; Lear, G.

2006-05-01

286

Capillary electrokinetic separations with optical detection. Technical progress report, February 1, 1993--January 31, 1994  

SciTech Connect

This program seeks the development of capillary electrokinetic separation techniques and associated optical methods of detection. Fundamental studies of pertinent separation and band broadening mechanisms are being conducted, with the emphasis on understanding systems that include highly-ordered assemblies as running buffer additives. The additives include cyclodextrins, affinity reagents, and soluble (entangled) polymers and are employed with capillary electrophoresis, CE and/or micellar electrokinetic capillary chromatography, MECC modes of separation. The utility of molecular modeling techniques for predicting the effects of highly ordered assemblies on the retention behavior of isomeric compounds is under investigation. The feasibility of performing separations using a non-aqueous solvent/fullerene electrochromatographic system is being explored. The analytical methodologies associated with these capillary separation techniques are being advanced through the development of retention programming instumentation/techniques and new strategies for performing optical detection. The advantages of laser fluorimetry are extended through the inclusion of fluorogenic, reagents in the running buffer. These reagents include oligonucleotide intercalation reagents for detecting DNA fragments. Chemiluminescence detection using post-capillary reactors/flow cells is also in progress. Successful development of these separation and detection systems will fill current voids in the capabilities of capillary separation techniques.

Sepaniak, M.J.

1993-10-01

287

Downhole Measurements of Electrokinetic Potential to Monitor Flow in Oilfields  

NASA Astrophysics Data System (ADS)

Oil companies currently produce an average of three barrels of water for each barrel of oil, which is expensive and environmentally unfriendly: the produced water is contaminated and must be treated and disposed of carefully. Ideally, water production would be prevented or minimised by monitoring its movement within the reservoir and responding appropriately. We suggest that measurements of electrokinetic (or ' streaming') potential during oil production, using permanently installed downhole electrodes, could be used to monitor water encroachment towards a well before water breakthrough occurs. Electrokinetic potentials are generated when fluids flow through rock, and although they are increasingly being used in other areas of earth science to monitor subsurface flows, there has been little investigation of their utility in hydrocarbon reservoirs. We have used a new numerical model to simulate the electrokinetic potential measured at a well during oil production, with reservoir pressure maintained by water injection or aquifer influx. Our results suggest that encroaching water causes changes in the electrokinetic potential at the well which could be resolved above background electrical noise; indeed, water approaching the well could be monitored several 10s to 100s of metres away. Our results differ from those obtained previously, because we include the results of recent laboratory experiments which provide new insight into the nature of the coupling between fluid and electrokinetic potentials as the oil saturation changes. Moreover, we investigate a range of production rates which are more appropriate for modern offshore developments, and simulate the potential measured at electrodes installed at the producing well rather than at a nearby monitoring well or at the surface. Electrodes mounted downhole on insulated casing have been successfully applied in subsurface resistivity surveys during oil production, and similar technology could be used to measure electrokinetic potential. If the producing well is equipped with downhole inflow control valves (so called ' intelligent' well technology), then oil production can be significantly enhanced if encroaching water is detected before it arrives and flow into the wellbore properly controlled. These findings raise the prospect of an oil field in which the wells can monitor the approach of water and respond appropriately. Such wells offer enormous potential economic and environmental benefits, particularly in fields which are difficult to access or dangerous to operate.

Saunders, J.; Jackson, M.; Pain, C.; Addiego-Guevara, E.

2005-12-01

288

Osteogenic activity and antibacterial effects on titanium surfaces modified with Zn-incorporated nanotube arrays.  

PubMed

Titanium implants having enhanced osteogenic activity and antibacterial property are highly desirable for the prevention of implant associated infection and promotion of osseointegration. In this study, coatings containing titania nanotubes (NTs) incorporated with zinc (NT-Zn) are produced on Ti implants by anodization and hydrothermal treatment in Zn containing solutions. The amount of incorporated Zn can be adjusted by varying the structural parameters such as the nanotube diameter and length as well as hydrothermal treatment time. The suitable NT-Zn coatings with good intrinsic antibacterial properties can prevent post-operation infection. Excellent osteogenesis inducing ability in the absence of extraneous osteogenic supplements is demonstrated and the ERK1/2 signaling is found to be involved. The NT-Zn structure which is simple, stable, and easy to produce and scale up has immense potential in bone implant applications. PMID:23439134

Huo, Kaifu; Zhang, Xuming; Wang, Hairong; Zhao, Lingzhou; Liu, Xuanyong; Chu, Paul K

2013-02-08

289

Effect of nickel incorporation on the optical properties of diamond-like carbon (DLC) matrix  

NASA Astrophysics Data System (ADS)

The present study investigates the optical behavior of composite nanostructured DLC based films and functional coatings. Diamond-like carbon (DLC) thin films were synthesized by electrodeposition method onto SnO 2 -coated glass substrates using an electrolyte of a mixture of acetic acid and water. Nanoparticles of nickel were then introduced into the DLC matrix. Morphology of the metal incorporated thin films and distribution of nanoparticles were studied by SEM; continuous homogeneous distribution of the particles was observed. Raman spectroscopy showed additional peaks in addition to the peaks due to DLC matrix. FTIR spectra revealed new peaks in the lower wave number region due to metal inclusion. UV-vis transmittance studies were performed to calculate the band gap of the samples. The estimated band gap from the Tauc relation was found to vary from 2.63 eV for the virgin DLC to 1.48 eV for the metal incorporated DLC.

Pandey, B.; Hussain, S.

2011-10-01

290

An improved ocean model of aluminium: the effects of circulation, sediment resuspension and biological incorporation  

NASA Astrophysics Data System (ADS)

The distribution of dissolved aluminium (Al) in the ocean is of interest because of its potential impact on diatom remineralisation and the use of surface ocean Al as a tracer for dust. Previously, the ocean Al concentration has been simulated reasonably well with only a dust source and scavenging as the removal process. In this study the simulation has been significantly improved by a more refined circulation and the addition of a sediment resuspension source. The latter confirms that the most significant sources of Al to the ocean are dust deposition and sediment resuspension. Simulations with biological incorporation have been performed as well. These show that this can be an important removal process. However, this study does not provide a definitive answer to the question what the relative amount of incorporation is compared to scavenging.

van Hulten, M. M. P.; Sterl, A.; Middag, R.; de Baar, H. J. W.; Gehlen, M.; Dutay, J.-C.; Tagliabue, A.

2013-09-01

291

Insulin effect on (/sup 14/C)-valine incorporation and its relation to hexokinase activity in developing brain  

SciTech Connect

Using minced brain cortex from fetal and postnatal rats, we studied the incorporation of (/sup 14/C)-valine into protein in the presence of insulin. We also assayed the particle bound and soluble hexokinase in these tissues. Insulin significantly stimulated the incorporation of (/sup 14/C)-valine into brain proteins from fetal stage upto 2 days of life. After this period the insulin effect was minimal, with no effect by day 5. The particle bound (40,000g pellet) brain hexokinase, on the other hand, remained low till about 2 days of life and then increased to almost adult level by 5 days. Our results show that there is an inverse relation between this anabolic effect of insulin and the particle bound hexokinase activity in the cortex of developing rat brain.

Pal, N.; Bessman, S.P.

1988-07-15

292

Effects of soluble cobalt and cobalt incorporated into calcium phosphate layers on osteoclast differentiation and activation  

Microsoft Academic Search

Metal ions originating from mechanical debris and corrosive wear of prosthetic implant alloys accumulate in peri-implant soft tissues, bone mineral, and body fluids. Eventually, metal ions such as cobalt (II) (Co2+), which is a major component of cobalt–chromium-based implant alloys and a known activator of osteolysis, are incorporated into the mineral phase of bone. We hypothesize that the accumulation of

Somying Patntirapong; Pamela Habibovic; Peter V. Hauschka

2009-01-01

293

Effect of fiber incorporation on rheological and chapati making quality of wheat flour  

Microsoft Academic Search

Traditional Indian unleavened bread (chapati) was prepared by incorporating wheat bran (insoluble fiber) and oat bran (soluble fiber) at different levels into whole wheat\\u000a flour. Central composite rotatable design with 2 independent variables (wheat bran and oat bran) at 5 levels (wheat bran 3–9,\\u000a oat bran 6–12%) was used to design the experiments. The flour samples containing different concentration of

D. N. Yadav; A. Rajan; G. K. Sharma; A. S. Bawa

2010-01-01

294

Effects of a Modified Dye-Labeled Nucleotide Spacer Arm on Incorporation by Thermophilic DNA Polymerases  

Microsoft Academic Search

The ability of eight commercially available thermophilic DNA polymerases to sequentially incorporate fluorescently labeled nucleotides sequentially was analyzed by a gel based primer extension assay. Cy5-dUTP or a variant nucleotide in which the linker had been lengthened by 14 atoms between the dye and the nucleobase were compared. We found that the Cy5-dUTP with a longer linker resulted in longer

Christopher J. Lacenere; Neil K. Garg; Brian M. Stoltz; Stephen R. Quake

2006-01-01

295

Saline or plant-incorporated methylmercury effects on distribution, demethylation, and blood parameters in rats  

SciTech Connect

The influence of diet is recognized as a significant factor in the expression of toxicity. This applies particularly to toxins like methylmercury (MeHg) which are metabolically incorporated into growing food plants and biotransformed within the plant before ingestion. Methylmercury in this form may influence the early physiological and biochemical events which lead to development of toxicity. In a previous study, a single dose of plant-incorporated methylmercury (MeHg) had a different route of distribution and accumulation in rat organs after 48 h than an equivalent dose of saline MeHg with the greatest accumulation being in red blood cells. Creatine, an important storage form of high energy phosphate in muscles is a primary indicator of erythropoietic dynamics under hypoxia, a sensitive indicator of hemolytic disease, red blood cell aging and impaired marrow efficiency. Since changes in creatine levels occur sooner than changes in other blood parameters, itself being neither synthesized nor metabolized by red blood cells, it can be used as a sensitive indicator of toxicity. The present work investigates the difference in a longer term, multiple-dose regime of saline or bean-incorporated MeHg ingestion with special attention being given to various blood parameters.

Czuba, M.; Komsta-Szumska, E.; Mortimer, D.C.; Champagne, C.

1987-03-01

296

Testing and evaluation of electrokinetic decontamination of concrete  

SciTech Connect

The goals and objectives of the technical task plan (TTP) are to (1) describe the nature and extent of concrete contamination within the Department of Energy (DOE) complex and emerging and commercial technologies applicable to these problems; (2) to match technologies to the concrete problems and recommend up to four demonstrations; (3) to initiate recommended demonstrations; and (4) to continue investigation and evaluation of the application of electrokinetic decontamination processes to concrete. This document presents findings of experimental and theoretical studies of the electrokinetic decontamination (EK) process and their implications for field demonstrations. This effort is an extension of the work performed under TTP 142005, ``Electroosmotic Concrete Decontamination. The goals of this task were to determine the applicability of EK for treating contaminated concrete and, if warranted, to evaluate EK as a potential technology for demonstration. 62 refs.

DePaoli, D.W.; Harris, M.T.; Ally, M.R. [Oak Ridge National Lab., TN (United States). Chemical Technology Div.] [and others

1996-10-01

297

Feasibility of electrokinetic soil remediation in horizontal Lasagna cells.  

PubMed

An integrated soil remediation technology called Lasagna has been developed that combines electrokinetics with treatment zones for use in low permeability soils where the rates of hydraulic and electrokinetic transport are too low to be useful for remediation of contaminants. The technology was developed by two groups, one involving industrial partners and the DOE and another involving US EPA and the University of Cincinnati, who pursued different electrode geometries. The Industry/DOE group has demonstrated the technology using electrodes and treatment zones installed vertically from the soil surface. We have demonstrated the feasibility of installing horizontal electrodes and treatment zones in subsurface soils by hydraulic fracturing, a process that we adapted from petroleum industry practices. When horizontal electrodes were connected to a dc power supply, uniform electrical potential gradients of 10-40 V/m were created in soil between the electrodes, inducing electroosmotic flow that facilitated movement of water and contaminants into treatment zones between the electrodes. PMID:10946126

Roulier, M; Kemper, M; Al-Abed, S; Murdoch, L; Cluxton, P; Chen, J; Davis-Hoover, W

2000-10-01

298

ELECTROKINETIC WAVE PHENOMENA IN FLUID-SATURATED GRANULAR MEDIA  

SciTech Connect

Electrokinetic (EK) phenomena in sediments arise from relative fluid motion in the pore space, which perturbs the electrostatic equilibrium of the double layer at the grain surface. We have developed EK techniques in the laboratory to monitor acoustic wave propagation in electrolyte-saturated, unconsolidated sediments. Our experimental results indicate that as an acoustic wave travels through electrolyte-saturated sand, it can generate electric potentials greater than 1 mV. A careful study of these potentials was performed using medium-grain sand and loose glass microspheres for a range of pore fluid salinities and ultrasonic frequencies. Experimental results are also shown to compare well with numerical and analytical modeling based on the coupled electrokinetic-Biot theory developed by Pride (1994).

Block, G

2005-03-29

299

Quantitative analysis of thuringiensin by micellar electrokinetic capillary chromatography  

Microsoft Academic Search

A method for quantitative analysis of thuringiensin is established using micellar electrokinetic capillary chromatography (MEKC). Tryptophan was used as an internal standard. The running buffer contained phosphate–borate (20 mM) and sodium dodecyl sulfate (100 mM) with 10% acetonitrile. Electrophoresis was conducted under a voltage of 15 kV for 20 min. The peak area ratio of thuringiensin to tryptophan was calculated

Cheng-Ming Liu; Yew-Min Tzeng

1998-01-01

300

Qualitative analysis of mycotoxins using micellar electrokinetic capillary chromatography  

Microsoft Academic Search

Naturally occurring mycotoxins are separated using micellar electrokinetic capillary chromatography. Trends in the retention of these toxins, resulting from changes in mobile-phase composition and pH, are reported and presented as a means of alleviating coelution problems. Two sets of mobile-phase conditions are determined that provide unique separation selectivity. The facile manner by which mobile-phase conditions can be altered, without changes

Ricky D. Holland; Michael J. Sepaniak

1993-01-01

301

On-line sample preconcentration techniques in micellar electrokinetic chromatography  

Microsoft Academic Search

This review provides an overview as well as a practical understanding of on-line sample concentration techniques in micellar electrokinetic chromatography (MEKC). MEKC as well as other capillary electrophoretic modes suffer from low concentration sensitivity due to minute sample volume and limited optical pathlength for on-capillary photometric detection. Two on-line sample preconcentration techniques, sample stacking and sweeping are known to be

Jong-Bok Kim; Shigeru Terabe

2003-01-01

302

Evaluation of Electrokinetic Remediation of Arsenic-contaminated Soils  

Microsoft Academic Search

The potential of electrokinetic (EK) remediation technology has been successfully demonstrated for the remediation of heavy\\u000a metal-contaminated fine-grained soils through laboratory scale and field application studies. Arsenic contamination in soil\\u000a is a serious problem affecting both site use and groundwater quality. The EK technology was evaluated for the removal of arsenic\\u000a from two soil samples; a kaolinite soil artificially contaminated

Soon-Oh Kim; Won-Seok Kim; Kyoung-Woong Kim

2005-01-01

303

Micellar electrokinetic chromatography in zero-electroosmotic flow environment  

Microsoft Academic Search

Micellar electrokinetic chromatography (MEKC) is conducted in polyacrylamide-coated capillaries under almost complete suppression of electroosmotic flow. The equations of migration and resolution for neutral solutes in this mode of MEKC operation are presented. The technique is termed reversed-flow MEKC (RF-MEKC) because, in contrast to MEKC in bare-silica capillaries (N-MEKC), solute migration order is reversed and solute migration time is inversely

George M. Janini; Gary M. Muschik; Haleem J. Issaq

1996-01-01

304

Effects of arsenic incorporation on jarosite dissolution rates and reaction products  

NASA Astrophysics Data System (ADS)

Batch dissolution experiments were undertaken on synthetic arsenojarosites at pH 2, pH 8, and in ultra-pure water to better understand the influence of As incorporation on the kinetics and reaction products of jarosite dissolution. Incongruent jarosite dissolution was observed in all experiments. Arsenojarosite lacks the pH dependency observed in K-jarosite dissolution, likely the result of surface arsenate-iron complexes preventing protonation at low pH and repelling hydroxyls at high pH. The stronger bonding of arsenate to iron, compared to sulfate to iron, leads to an enrichment of surface layer arsenate-iron complex sites, inhibiting the dissolution of jarosite with time. The secondary reaction products formed during the dissolution of arsenojarosite include maghemite, goethite, and hematite in ultra-pure water, and ferrihydrite in pH 8 Tris buffered solution. Maghemite initially forms and transitions to hematite with time in ultra-pure water, but increasing arsenic concentrations slow this transition. At pH >3.5, arsenic from the dissolution of arsenojarosite adsorbs onto newly formed reaction products. Arsenic also inhibits the formation of goethite and reduces the crystallinity of the observed maghemite reaction products. The coprecipitation of iron oxides with increasing amounts of arsenic results in a change from spherical to "worm-like" aggregate morphology and provides a sink for arsenic released during arsenojarosite dissolution. This study shows that in open systems with a flush of fresh solution, arsenic incorporation in jarosite results in an increase in dissolution rates. In closed systems, however, increasing surface arsenate-iron complexes inhibit further dissolution of the underlying bulk material, causing a reduction in dissolution rates as arsenic incorporation increases.

Kendall, Matthew R.; Madden, Andrew S.; Elwood Madden, Megan E.; Hu, Qinhong

2013-07-01

305

Optimization of an electrokinetic mixer for microfluidic applications  

PubMed Central

This work is concerned with the investigation of the concentration fields in an electrokinetic micromixer and its optimization in order to achieve high mixing rates. The mixing concept is based on the combination of an alternating electrical excitation applied to a pressure-driven base flow in a meandering microchannel geometry. The electrical excitation induces a secondary electrokinetic velocity component, which results in a complex flow field within the meander bends. A mathematical model describing the physicochemical phenomena present within the micromixer is implemented in an in-house finite-element-method code. We first perform simulations comparable to experiments concerned with the investigation of the flow field in the bends. The comparison of the complex flow topology found in simulation and experiment reveals excellent agreement. Hence, the validated model and numerical schemes are employed for a numerical optimization of the micromixer performance. In detail, we optimize the secondary electrokinetic flow by finding the best electrical excitation parameters, i.e., frequency and amplitude, for a given waveform. Two optimized electrical excitations featuring a discrete and a continuous waveform are discussed with respect to characteristic time scales of our mixing problem. The results demonstrate that the micromixer is able to achieve high mixing degrees very rapidly.

Bockelmann, Hendryk; Heuveline, Vincent; Barz, Dominik P. J.

2012-01-01

306

Environment effects on the lasing photostability of Rhodamine 6G incorporated into organic-inorganic hybrid materials  

Microsoft Academic Search

The effect on the lasing photostability of Rhodamine 6G (Rh6G), and the rigidity of a hybrid inorganic-organic matrix by controlled addition of di-, tri- and tetrafunctionalized alkoxides has been evaluated. The dye was incorporated into hybrid matrices of (2-hydroxyethyl methacrylate) (HEMA) or vol\\/vol copolymers of methyl methacrylate (MMA) and HEMA with different weight proportions of polycondensated dimethyldiethoxysilane (DEOS), methyltriethoxysilane (TRIEOS),

A. Costela; I. García-Moreno; C. Gómez; O. García; R. Sastre

2004-01-01

307

Effective control of flat-band voltage in HfO2 gate dielectric with La2O3 incorporation  

Microsoft Academic Search

The origin of negative flat-band shift using La2O3 incorporation in HfO2 dielectrics has been extensively examined. From careful extraction of effective work function of gate electrode and fixed charges at each interface, it has been revealed that La2O3 at high-k\\/Si substrate or high-k\\/SiO2 interface has either large amount of positive fixed charges or an additional dipole of 0.36 V compared

K. Okamoto; M. Adachi; K. Kakushima; P. Ahmet; N. Sugii; K. Tsutsui; T. Hattori; H. Iwai

2007-01-01

308

Atomic scale effects of zirconium and hafnium incorporation at a model silicon\\/silicate interface by first principles calculations  

Microsoft Academic Search

First principles calculations aimed at quantifying the effects of zirconium and hafnium incorporation at a model silicon\\/silicate interface have been performed. The tetrahedral bonding character of silicates allows useful comparisons as well as important new distinctions to be drawn with the familiar Si\\/SiO2 system. The calculated energy cost of forming (Zr,Hf)-Si bonds suggests that SiO 2-like bonding is energetically favored

Atsushi Kawamoto; John Jameson; Peter Griffin; Kyeongjae Cho; Robert Dutton

2001-01-01

309

Effects of titanium surface anodization with CaP incorporation on human osteoblastic response.  

PubMed

In this study we investigated whether anodization with calcium phosphate (CaP) incorporation (Vulcano®) enhances growth factors' secretion, osteoblast-specific gene expression, and cell viability, when compared to acid etched surfaces (Porous®) and machined surfaces (Screw®) after 3 and 7days. Results showed significant cell viability for Porous and Vulcano at day 7, when compared with Screw (p=0.005). At the same time point, significant differences regarding runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP) and bone sialoprotein (BSP) expression were found for all surfaces (p<0.05), but with greater fold induction for Porous and Vulcano. The secretion of transforming growth factor ?1 (TGF-?1) and bone morphogenetic protein 2 (BMP-2) was not significantly affected by surface treatment in any experimental time (p>0.05). Although no significant correlation was found for growth factors' secretion and Runx2 expression, a significant positive correlation between this gene and ALP/BSP expression showed that their strong association is independent on the type of surface. The incorporation of CaP affected the biological parameters evaluated similar to surfaces just acid etched. The results presented here support the observations that roughness also may play an important role in determining cell response. PMID:23498218

Oliveira, Natássia Cristina Martins; Moura, Camilla Christian Gomes; Zanetta-Barbosa, Darceny; Mendonça, Daniela Baccelli Silveira; Cooper, Lyndon; Mendonça, Gustavo; Dechichi, Paula

2013-01-11

310

Effect of cholesterol on distribution of stable, hydrophobic perchlorotriphenylmethyl triethylester radical incorporated in lecithin liposomal membranes.  

PubMed

Perchlorotriphenylmethyl triethylester radical (PTM-TE) is a hydrophobic, stable radical giving a narrow singlet ESR signal with a small satellite signal for (13)C in organic solvents. In order to use PTM-TE as a label of liposomal membranes, its manner of incorporation into liposomal membranes was studied. Two components, broad and narrow signals, were observed on the ESR spectrum of PTM-TE incorporated into liposomal membranes composed of egg yolk phosphatidylcholine (egg-PC). The broad signal was increased by the presence of cholesterol in the membranes. The spectral anisotropy of the broad signal was very small as analyzed with oriented planar multilamellar membranes. The narrow signal increased with an increase in temperature in the absence of cholesterol, whereas only a small increase in the signal was observed in the presence of cholesterol. The g-value and line width of the narrow signal were very close to those of PTM-TE in mineral oil, whose viscosity is close to the microviscosity in the hydrophobic region of egg-PC membranes. On the other hand, the g-value and line width of the broad signal were close to those of solid PTM-TE. These observations indicate that the broad signal observed in liposomes originates from PTM-TE clusters in the membranes. The clusters were dissolved in egg-PC membranes at a PTM-TE/egg-PC molar ratio of less than 0.017. However, the clusters were hardly dissolved in the presence of cholesterol. PMID:21532201

Takeshita, Keizo; Okazaki, Shoko; Kansui, Hisao

2011-01-01

311

Electrokinetic Ion Transport through Unsaturated Soil: 1) Theory, Model Development, and Testing 2) Application to a Heterogeneous Field Site  

SciTech Connect

An electromigration transport model for non-reactive ion transport in unsaturated soil was developed and tested against laboratory experiments. This model assumed the electric potential field was constant with respect to time, an assumption valid for highly buffered soil, or when the electrode electrolysis reactions are neutralized. The model also assumed constant moisture contents and temperature with respect to time, and that electroosmotic and hydraulic transport of water through the soil was negligible. A functional relationship between ionic mobility and the electrolyte concentration was estimated using the chemical activity coefficient. Tortuosity was calculated from a mathematical relationship fitted to the electrical conductivity of the bulk pore water and soil moisture data. The functional relationship between ionic mobility, pore-water concentration, and tortuosity as a function of moisture content allowed the model to predict ion transport in heterogeneous unsaturated soils. The model was tested against laboratory measurements assessing anionic electromigration as a function of moisture content. In the test cell, a strip of soil was spiked with red dye No 40 and monitored for a 24-h period while a 10-mA current was maintained between the electrodes. Electromigration velocities predicted by the electromigration transport model were in agreement with laboratory experimental results. Both laboratory-measured and model-predicted dye migration results indicated a maximum transport velocity at moisture contents less than saturation due to competing effects between current density and tortuosity as moisture content decreases. Results of a field demonstration of electrokinetic transport of acetate through an unsaturated heterogeneous soil are compared to numerical modeling predictions. The numerical model was based on the groundwater flow and transport codes MODFLOW and MT3D modified to account for electrically induced ion transport. The 6-month field demonstration was conducted in an unsaturated layered soil profile where the soil moisture content ranged from 4% to 28% (m3 m-3). Specially designed ceramic-cased electrodes maintained a steady-state moisture content and electric potential field between the electrodes during the field demonstration. Acetate, a byproduct of acetic acid neutralization of the cathode electrolysis reaction, was transported from the cathode to the anode by electromigration. Field demonstration results indicated preferential transport of acetate through soil layers exhibiting higher moisture content/electrical conductivity. These field transport results agree with theoretical predictions that electromigration velocity is proportional to a power function of the effective moisture content. A numerical model using a homogeneous moisture content/electrical conductivity domain did not adequately predict the acetate field results. Numerical model predictions using a three-layer electrical conductivity/moisture content profile agreed qualitatively with the observed acetate distribution. These results suggest that field heterogeneities must be incorporated into electrokinetic models to predict ion transport at the field-scale.

Mattson, Earl Douglas; Bowman, R. S.; Lindgren, E. R.

2002-01-01

312

Micelle to solvent stacking of organic cations in micellar electrokinetic chromatography with sodium dodecyl sulfate  

Microsoft Academic Search

The on-line sample concentration technique, micelle to solvent stacking (MSS), was studied for small organic cations (quaternary ammonium herbicides, ?-blocker drugs, and tricyclic antidepressant drugs) in reversed migration micellar electrokinetic chromatography. Electrokinetic chromatography was carried out in fused silica capillaries with a background solution of sodium dodecyl sulfate (SDS) in a low pH phosphate buffer. MSS was performed using anionic

Joselito P. Quirino; Agnes T. Aranas

2011-01-01

313

On connection between the electrokinetic properties of cell nuclei and human biological age  

Microsoft Academic Search

An original method of intracellular microelectrophoresis of cell nuclei has been developed and using this technique the dependence of the electrokinetic potential of cell nuclei on the human age is calculated. This new method, obtained for every age group, allows the calculation of electrokinetic potentials, the determination of human biological ages and changes in energies of an organism provoked by

Valery G Shakhbazov; Yury G Shookorbatov; Tamara V Colupaeva

1997-01-01

314

Electrokinetic iron pan generation in unconsolidated sediments: implications for contaminated land remediation and soil engineering  

Microsoft Academic Search

Electrokinetic remediation is an emerging technology that has generated considerable interest as a technique for the in situ remediation of clay-rich soils and sediments. Despite promising experimental results, however, at present there is no standardised universal electrokinetic soil\\/sediment remediation approach. Many of the current technologies are technically complex and energy intensive, and geared towards the removal of 90% or more

A. B. Cundy; L. Hopkinson

2005-01-01

315

Effect of Length of Time before Incorporation on Survival of Pathogenic Bacteria Present in Livestock Wastes Applied to Agricultural Soil  

PubMed Central

In response to reports that the contamination of food can occur during the on-farm primary phase of food production, we report data that describes a possible cost-effective intervention measure. The effect of time before soil incorporation of livestock wastes spread to land on the rate of decline of zoonotic agents present in the waste was investigated. Fresh livestock wastes were inoculated with laboratory-cultured Salmonella, Listeria, and Campylobacter spp. and Escherichia coli O157 before they were spead onto soil. Incorporation of the spread wastes was either immediate, delayed for 1 week, or did not occur at all. Bacterial decline was monitored over time and found to be significantly more rapid for all waste types when they were left on the soil surface. There were no significant differences in initial bacterial decline rates when wastes were spread in summer or winter. Our results indicate that not incorporating contaminated livestock wastes into soil is a potential intervention measure that may help to limit the spread of zoonotic agents further up the food chain. The implications of these findings are discussed in relation to current advice for livestock waste disposal.

Hutchison, M. L.; Walters, L. D.; Moore, A.; Crookes, K. M.; Avery, S. M.

2004-01-01

316

Effect of oxygen incorporation on normal and superconducting properties of MgB2 films  

NASA Astrophysics Data System (ADS)

Oxygen was systematically incorporated in MgB2 films using in situ postgrowth anneals in an oxygen environment. Connectivity analysis in combination with measurements of the critical temperature (Tc) and resistivity (?) indicate that oxygen is distributed both within and between the grains. High values of critical current densities (Jc) in field (~4×105 A/cm2 at 8 T and 4.2 K), extrapolated critical fields [Hc2(0)] (>45 T), and slopes of critical field versus temperature (1.4 T/K) are observed. Our results suggest that low growth temperatures (300 °C) and oxygen doping (>=0.65%) can produce MgB2 with high Jc values in field and Hc2 for high-field magnet applications.

Singh, R. K.; Shen, Y.; Gandikota, R.; Carvalho, C.; Rowell, J. M.; Newman, N.

2008-12-01

317

13-Acetoxy-13-desmethylretinal: Synthesis incorporation into bacteriorhodopsin, and its apparent inactivating effect  

SciTech Connect

Bacteriorhodopsin (bR), the protein pigment of the purple membrane (PM) light-driven proton pump, is a single polypeptide chain of 248 amino acids. It traverses the membrane to form seven rods of high [alpha]-helical character. PM's color results from the presence of an equivalent of retinal, bound as a protonated Schiff base (PRSB) at lysine 216, and its interaction with the protein. Light initiates a photocycle where the first step is a photoisomerization of all-trans-retinal to the 13-cis isomer. All subsequent steps in the cycle are thermal dark reactions. We report herein the synthesis and incorporation into bacteriorhodopsin of a novel analogue, 13-acetoxy-13-desmethylretinal designed to probe the mechanism of dark cis-trans isomerization. 24 refs., 1 fig.

Seltzer, S. (Brookhaven National Lab., Upton, NY (United States))

1994-10-05

318

Electrokinetic control of sample splitting at a channel bifurcation using isotachophoresis  

NASA Astrophysics Data System (ADS)

We present a novel method for accurately splitting ionic samples at microchannel bifurcations. We leverage isotachophoresis (ITP) to focus and transport sample through a one-inlet, two-outlet microchannel bifurcation. We actively control the proportion of splitting by controlling potentials at end-channel reservoirs (and thereby controlling the current ratio). We explore the effect of buffer chemistry and local electric field on splitting dynamics and propose and validate a simple Kirchoff-type rule controlling the split ratio. We explore the effects of large applied electric fields on sample splitting and attribute a loss of splitting accuracy to electrohydrodynamic instabilities. We propose a scaling analysis to characterize the onset of this instability. This scaling is potentially useful for other electrokinetic flow problems with self-sharpening interfaces.

Persat, Alexandre; G Santiago, Juan

2009-07-01

319

Soil Carbon Dioxide Emissions from Sorghum–Sunflower Rotation in Rainfed Semi-arid Tropical Alfisols: Effects of Fertilization Rate and Legume Biomass Incorporation  

Microsoft Academic Search

The long-term effects of plant legume [horse gram (Macrotyloma uniflorum)] biomass incorporations were assessed in terms of carbon dioxide (CO2) emissions, soil quality parameters, and climatically influenced soil parameters in a dryland Alfisol under varying soil fertility conditions. Six selected treatments consisted of off-season legume incorporation (I) and no incorporation?\\/?fallow (F), each under three varying nitrogen and phosphorus fertilizer levels

V. Ramesh; B. Venkateswarlu; K. L. Sharma; S. P. Wani

2012-01-01

320

Soil Carbon Dioxide Emissions from Sorghum-Sunflower Rotation in rainfed Semi Arid tropical Alfisols: Effects of Fertilization rate and Legume Biomass Incorporation  

Microsoft Academic Search

The long-term effects of plant legume [horse gram (Macrotyloma uniflorum)] biomass incorporations were assessed in terms of carbon dioxide (CO2) emissions, soil quality parameters, and climatically influenced soil parameters in a dryland Alfisol under varying soil fertility conditions. Six selected treatments consisted of off season legume incorporation (I) and without incorporation\\/fallow (F) each under three varying nitrogen and phosphorus fertilizer

V. Ramesh; B. Venkateswarlu; K. L. Sharma; S. P. Wani

2012-01-01

321

Effect on days of lactation and methionine hydroxy analog on incorporation of plasma fatty acids into plasma triglycerides  

SciTech Connect

Methionine hydroxy analog has been proposed to stimulate hepatic lipoprotein synthesis and incorporation of plasma fatty acids into plasma triglyceride. Seven cows were fed diets containing 0 to 30 g analog/d starting 14 d prepartum. At approximately 30 and 60 d postpartum, cows were continuously infused intravenously with 1-({sup 14}C)palmitic acid for 160 min to achieve steady-state labeling of plasma fatty acid and triglyceride. Turnover of fatty acid and transfer quotients for triglyceride and CO{sub 2} were 3.3 an 2.7 mmol min{sup {minus}1}; 13.0 and 10.0%; and 8.0 and 5.0%, for control and analog, respectively. Proportion of fatty acid turnover incorporated into triglyceride and CO{sub 2} were 14.0 and 15.0%; and 21.0 and 18.0, respectively, for control and analog. Analog increased {sup 14}C recovered in milk fat (52 vs. 36%). Plasma concentration of fatty acids, percent oxidized to CO{sub 2}, and percent of CO{sub 2} from fatty acids decreased with increasing lactation days. Milk fat percent and yield fatty acid turnover, and oxidation were positively correlated with concentration of plasma fatty acids, whereas fatty acid incorporated into plasma triglyceride was negatively correlated with fatty acid concentration. The data suggest that hepatic triglyceride secretion is not increased in early lactation; further, no effects of analog on lipid metabolism were detected.

Pullen, D.L.; Emergy, R.S. (Michigan State Univ., East Lancing (USA)); Palmquist, D.L. (Ohio State Univ., Wooster (USA))

1989-01-01

322

Effects of retroviral envelope-protein cleavage upon trafficking, incorporation, and membrane fusion  

SciTech Connect

Retroviral envelope glycoproteins undergo proteolytic processing by cellular subtilisin-like proprotein convertases at a polybasic amino-acid site in order to produce the two functional subunits, SU and TM. Most previous studies have indicated that envelope-protein cleavage is required for rendering the protein competent for promoting membrane fusion and for virus infectivity. We have investigated the role of proteolytic processing of the Moloney murine leukemia virus envelope-protein through site-directed mutagenesis of the residues near the SU-TM cleavage site and have established that uncleaved glycoprotein is unable either to be incorporated into virus particles efficiently or to induce membrane fusion. Additionally, the results suggest that cleavage of the envelope protein plays an important role in intracellular trafficking of protein via the cellular secretory pathway. Based on our results it was concluded that a positively charged residue located at either P2 or P4 along with the arginine at P1 is essential for cleavage.

Apte, Swapna, E-mail: apte@purdue.ed [Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392 (United States); Sanders, David Avram, E-mail: retrovir@purdue.ed [Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392 (United States)

2010-09-15

323

Indium incorporation effects on luminescence mechanisms in quaternary AlInGaN layers  

NASA Astrophysics Data System (ADS)

The optical and structural properties of quaternary AlInGaN layers grown by a pulsed metalorganic chemical vapor deposition (PMOCVD) have been investigated by means of photoluminescence (PL) and time-resolved PL (TRPL) measurements and X-ray diffraction. The AlInGaN layers show strong blueshift and linewidth broadening of the PL emission band with increasing excitation power. With increasing indium mole fraction, the AlInGaN layer exhibited a stronger PL intensity, a faster PL decay, and a smaller lattice mismatch between the AlInGaN layer and the GaN buffer layer. Based on both the PL and TRPL data, we suggest that the incorporation of indium creates more band-tail states and enhances the luminescence efficiency, indicating that the PMOCVD-grown AlInGaN is better suited as the active region material for ultraviolet light-emitting diodes than conventional MOCVD-grown AlInGaN.

Ryu, Mee-Yi; Song, J. H.; Chen, C. Q.; Asif Khan, M.

2007-06-01

324

Effect of dietary stable isotopic ratios of carbon and nitrogen on the extent of their incorporation into tissues of rats  

PubMed Central

This study was conducted to investigate the effect of different dietary ratios of 13?C to 12?C or 15?N to 14?N on their relative incorporation into tissues. Eighty male rats were used in two 21-day feeding trials in which they were fed diets with either high ?13C levels (?13C?=??13.89‰ and ?15N?=?2.37‰ in experiment 1 and ?13C?=??19.34‰ and ?15N?=?4.73‰ in experiment 2) or low ?13C levels (?13C?=??17.90‰ and ?15N?=?3.08‰ in experiment 1 and ?13C?=??21.76‰ and ?15N?=?0.53‰ in experiment 2), meanwhile, the dietary ?15N levels were designed to two ranks. Blood, liver, adipose and muscle tissues were collected on day 0, 3, 7, 14, and 21 for determination of 13?C, 12?C, 15?N and 14?N isotopes. Rat growth rate, antioxidant capacity and metabolic parameters were also assessed. The results indicate that adipose tissue tend to deplete 13?C before the stable isotopic ratios achieved final equilibrium. Therefore, feeds with different isotopic signatures had different incorporation rates into tissues. Low dietary 13?C levels decreased tissue ?13C values whereas high dietary 13?C levels did not alter tissue ?13C values during the 21-d experiment. Blood ?15N values were a reliable parameter in assessing the relative contribution of dietary nitrogen to tissues. This study revealed a relationship between dietary isotopic signatures and their incorporation rates into rat tissues. However, more studies are needed to illustrate the mechanism through which dietary isotopic ratios influence the extent of isotopic incorporation into the tissues.

2012-01-01

325

On-line micellar electrokinetic chromatography-electrospray ionization mass spectrometry using anodically migrating micelles  

SciTech Connect

On-line micellar electrokinetic chromatography (MEKC)-electrospray ionization mass spectrometry (ESIMS) is demonstrated for the analysis of chlorotriazine herbicides and barbiturates. In this study, the micellar velocity is directly manipulated by the adjustment of electroosmosis rather than the electrophoretic velocity of the micelle. The electroosmotic flow is adjusted against the electrophoretic velocity of the micelle by changing the solution pH in MEKC. The elimination of MEKC surfactant introduction into ESIMS is achieved with an anodically migrating micelle, moving away from the electrospray interface. The effects of moving surfactant boundary in the MEKC capillary on separation efficiency and resolution of triazine herbicides and barbiturates are investigated. The mass detection of herbicides and barbiturates sequentially eluted from the MEKC capillary is acquired using the positive and negative electrospray modes, respectively. 30 refs., 8 figs., 3 tabs.

Yang, L.; Harrata, A.K.; Lee, C.S. [Ames Lab., IA (United States)]|[Iowa State Univ., Ames, IA (United States)

1997-05-15

326

Continuous Signal Enhancement for Sensitive Aptamer Affinity Probe Electrophoresis Assay Using Electrokinetic Concentration  

PubMed Central

We describe an electrokinetic concentration-enhanced aptamer affinity probe electrophoresis assay to achieve highly sensitive and quantitative detection of protein targets in a microfluidic device. The key weaknesses of aptamer as a binding agent (weak binding strength/fast target dissociation) were counteracted by continuous injection of fresh sample while band-broadening phenomena were minimized due to self-focusing effects. With 30 minutes of continuous signal enhancement, we can detect 4.4 pM of human immunoglobulin E (IgE) and 9 pM of human immunodifficiency virus 1 reverse transcriptase (HIV-1 RT), which is among the lowest limit of detection (LOD) reported. IgE was detected in serum sample with LOD of 39 pM due to nonspecific interactions between aptamers and serum proteins. The method presented in this paper also has broad applicability to improve sensitivities of various other mobility shift assays.

Cheow, Lih Feng; Han, Jongyoon

2011-01-01

327

Interactions of structurally modified surfactants with reservoir minerals: Calorimetric, spectroscopic and electrokinetic study  

SciTech Connect

The objective of this project is to elucidate mechanisms of adsorption of structurally modified surfactants on reservoir minerals and to develop a full understanding of the effect of the surfactant structure on the nature of the adsorbed layers at the molecular level. An additional aim is to study the adsorption of surfactant mixtures on simple well-characterized minerals and on complex minerals representing real conditions. The practical goal of these studies is the identification of the optimum surfactant structures and their combinations for micellar flooding. In this work, the experiments on adsorption were focussed on the position of sulfonate and methyl groups on the aromatic ring of alkyl xylene sulfonates. A multi-pronged approach consisting of calorimetry, electrokinetics, wettability and spectroscopy is planned to elucidate the adsorption mechanism of surfactants and their mixtures on minerals such as alumina and kaolinite. 32 refs., 15 figs., 7 tabs.

Somasundaran, P.; Sivakumar, A.; Xu, Q.

1991-03-01

328

Colloidal particle motion in micro galvanic reactors through tailored electrokinetic fluid flow  

NASA Astrophysics Data System (ADS)

Using an array of galvanic micro electrodes (e.g., anodic copper and cathodic gold) in contact with an acidic colloidal suspension, we have previously demonstrated autonomous control of particle trajectory and the location of particle deposition which affected the crystallinity of 2D colloidal crystals on the anodes. Particle velocities and the locations of initial particle deposition are affected by the electrode geometry and reaction time. We now present data on the effects of geometry and time on the copper dissolution rate and the associated electrokinetic phenomena. Particle velocities increase with the copper dissolution rate and the steepness of its lateral variation. Experiments and theoretical results reveal that the different location of deposition is related to the difference in the lateral gradient of the dissolution rate.

Jan, Linda; Punckt, Christian; Khusid, Boris; Aksay, Ilhan A.

2010-11-01

329

Analyses of tobacco alkaloids by cation-selective exhaustive injection sweeping microemulsion electrokinetic chromatography.  

PubMed

In this study, an on-line concentration method which coupled cation-selective exhaustive injection (CSEI) sweeping technology with microemulsion electrokinetic chromatography (MEEKC) was used to detect and analyze several tobacco alkaloids (nornicotine, anabasine, anatabine, nicotine, myosmine and cotinine) that are commonly found in various tobacco products. First, the effects of microemulsion compositions (oil, cosurfactant and solution pH) were examined in order to optimize the alkaloid separations in conventional MEEKC. The pH value and the injection length of basic plug were found to be the predominant influences on the alkaloid stacking. This optimal CSEI sweeping MEEKC method provided approximately 180- to 540-fold increase in detection sensitivity in terms of peak height without any loss in separation efficiency when compared to normal MEEKC separation. Furthermore, this proposed CSEI sweeping MEEKC method was applied successfully for the detection of the minor alkaloids nornicotine, anabasine and anatabine in tobacco products. PMID:17644105

Huang, Hsi-Ya; Hsieh, Shih-Huan

2007-07-05

330

Measuring the short-term effects of incorporating academic service learning throughout a dental hygiene curriculum.  

PubMed

OBJECTIVES: Academic service learning (ASL) provides the venue for dental hygiene education to take oral healthcare services directly into communities while at the same time promoting professional responsibility within the student bodies. The purpose of this study was to quantitatively examine the change in pre-existing attitudes and behaviours of dental hygiene students following the incorporation of ASL activities throughout a five-semester dental hygiene curriculum. METHODS: Seventy-seven first-year dental hygiene students who participated in ASL from the graduating classes of 2008-2010 participated in the study. A survey instrument developed by Shiarella, based on Schwartz's Helping Behaviors Model, was used to assess students' attitudes towards community service. Additionally, questions were developed using Shinnamon's Methods and Strategies for Assessing Service-Learning in the Health Professions. RESULTS: Internal estimates of reliability for scales (Cronbach's ?) were all >0.8. The results revealed statistically significant improvements over time in enhanced learning (P = 0.0001), self-awareness (P = 0.0001), sense of volunteerism (P = 0.013), impact on career choices (P = 0.001) and decrease in personal costs (P = 0.0001). There were no significant changes in other subscales over time. Further investigating these domains revealed minimal to no changes in attributes of service learning. CONCLUSION: Service learning integrated into the dental hygiene curriculum can enhance learning and improve students' self-awareness, sense of volunteerism, career choices and perception of personal costs. In concert with the literature on ASL, these experiences throughout the curriculum have potential for increasing students' awareness of community need and their roles as oral health professionals. PMID:23406472

Simmer-Beck, M; Gadbury-Amyot, C; Williams, Kb; Keselyak, Nt; Branson, B; Mitchell, Tv

2013-02-13

331

The effect of nitrogen incorporation on the bonding structure of hydrogenated carbon nitride films  

SciTech Connect

This work describes the composition and bonding structure of hydrogenated carbon nitride (a-CN{sub x}:H) films synthesized by electron cyclotron resonance chemical vapor deposition using as precursor gases argon, methane, and nitrogen. The composition of the films was derived from Rutherford backscattering and elastic recoil detection analysis and the bonding structure was examined by infrared (IR) spectroscopy and x-ray absorption near edge spectroscopy (XANES). By varying the nitrogen to methane ratio in the applied gas mixture, polymeric a-CN{sub x}:H films with N/C contents varying from 0.06 to 0.49 were obtained. Remarkably, the H content of the films ({approx}40 at. %) was rather unaffected by the nitrogenation process. The different bonding states as detected in the measured XANES C(1s) and N(1s) spectra have been correlated with those of a large number of reference samples. The XANES and IR spectroscopy results indicate that N atoms are efficiently incorporated into the amorphous carbon network and can be found in different bonding environments, such as pyridinelike, graphitelike, nitrilelike, and amino groups. The nitrogenation of the films results in the formation of N-H bonding environments at the cost of C-H structures. Also, the insertion of N induces a higher fraction of double bonds in the structure at the expense of the linear polymerlike chains, hence resulting in a more cross-linked solid. The formation of double bonds takes place through complex C=N structures and not by formation of graphitic aromatic rings. Also, the mechanical and tribological properties (hardness, friction, and wear) of the films have been studied as a function of the nitrogen content. Despite the major modifications in the bonding structure with nitrogen uptake, no significant changes in these properties are observed.

Camero, M.; Buijnsters, J. G.; Gomez-Aleixandre, C.; Gago, R.; Caretti, I.; Jimenez, I. [Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), C/ Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain); Centro de Micro-Analisis de Materiales (CMAM) and Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, C/ Faraday 3, Cantoblanco, 28049 Madrid (Spain); Department of Physics, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk (Belgium); Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), C/ Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain); Instituto de Ciencia y Tecnologia de Polimeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid (Spain)

2007-03-15

332

Enhanced perpendicular magnetic anisotropy in Fe/Mn bilayers by incorporating ultrathin ferromagnetic underlayer through magnetic proximity effect  

NASA Astrophysics Data System (ADS)

The perpendicular magnetic anisotropy(PMA) was shown to be established in ferromagnetic (FM)/fcc-Mn bilayers through the FM-antiferromagnetic (AFM) exchange coupling. We demonstrate here that such PMA can be further enhanced by incorporating an ultrathin Fe film as an underlayer. In a series of Fe/Mn bilayers, hysteresis loop measurement shows that the thickness of top Fe layer with PMA can be extended to a thicker range while an ultrathin Fe underlayer is inserted. Such enhancement of PMA is attributed to an increase of AFM ordering on the Mn film originated from the magnetic proximity effect with the Fe underlayer.

Wang, Bo-Yao; Chiu, Chieh-Chen; Lin, Wen-Chin; Lin, Minn-Tsong

2013-07-01

333

THE LOCAL EFFECT TIME (LET) AND HOW IT INCORPORATES ECOLOGY INTO RESIDENCE TIME  

EPA Science Inventory

A clear and direct connection between constituent/water residence times and ecological effects is necessary to quantitatively relate these time scales to ecology. The concept of "local effect time" (LET) is proposed here as a time scale with adequate spatial resolution to relate ...

334

Development of improved Li-ion battery model incorporating thermal and rate factor effects  

Microsoft Academic Search

This paper presents development of an improved electrical circuit based Li-ion battery model using AMESim. This model considers charge extraction due to current, battery capacity, and effect of internal resistance and extends the thermal aspects which represent temperature rise in the core and crust. The thermal aspects that characterize the temperature rise in core and crust and its effects on

Sachin Bhide; Taehyun Shim

2009-01-01

335

Micellar electrokinetic capillary chromatography of psoralen and isopsoralen.  

PubMed

In this paper, a micellar electrokinetic capillary chromatography (MEKC) method to analyze the active components of psoralen and isopsoralen in the Chinese herb Psoralea corylifolia L. was developed. It was found that the optimum separation condition for the analysis of these compounds was a buffer solution which contained phosphate, borate and sodium dodecyl sulfate (pH 9.2). Through optimization of the experimental condition, the two isomers could be baseline-separated and their contents in the methanol-extracted sample were quantitatively analyzed. PMID:10445332

Wang, D; Yang, G; Engelhardt, H; Zhang, H

1999-07-01

336

5Hydroxymethylfurfural content in foodstuffs determined by micellar electrokinetic chromatography  

Microsoft Academic Search

Micellar electrokinetic chromatography (MEKC) has been applied for the determination of 5-hydroxymethylfurfural in several foodstuffs. A 75mM phosphate buffer solution at pH 8.0 containing 100mM sodium dodecylsulphate was used as background electrolyte (BGE), and the separation was performed by applying +25kV in a 50?m I.D. uncoated fused-silica capillary. Good linearity over the range 2.5–250mgkg?1 (r2?0.999) and run-to-run and day-to-day precisions

Erika Teixidó; Oscar Núñez; F. Javier Santos; M. Teresa Galceran

2011-01-01

337

Cyclodextrin-modified micellar electrokinetic chromatography for enantioseparations.  

PubMed

The separation of enantiomers is one of the important fields of modern analytical chemistry, especially for agrochemical and pharmaceutical products because the stereochemistry has a significant influence on the biological activities of compounds. Cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) has become an important capillary electrophoresis mode for enantioseparations. Here, we describe an example of a CD-MEKC method using hydroxypropyl-?-cyclodextrin as chiral selector and sodium dodecyl sulfate as micellar solution for enantioseparation of triazole fungicides and the drug econazole. PMID:23283789

Ibrahim, Wan Aini Wan; Hermawan, Dadan; Sanagi, Mohd Marsin

2013-01-01

338

On the electrokinetic energy conversion in liquid mixtures  

NASA Astrophysics Data System (ADS)

The dependence of the maximum efficiency of the electrokinetic energy conversion, (eta)max, on the composition of liquid mixtures is studied. Experiments on streaming potential and electroosmosis were conducted with Pyrex glass plugs using aqueous mixtures of different alcohols as permeants in order to investigate the influence of the properties of the permeant on the energy conversion process. A strong dependence is found between the quantities (eta)max and D sq/lambda mu, where mu is the absolute viscosity, lambda is the specific conductance of the liquid permeant, and D equals epsilon/epsilon sub 0, where epsilon is the absolute dielectric constant.

Hidalgo-Alvarez, R.; Gonzalez-Caballero, F.; Pardo, G.

1983-03-01

339

An Investigation into a Methodology to Incorporate Skill Level Effects into the Logistics Composite Model.  

National Technical Information Service (NTIS)

The Logistics Composite Model (LCOM), a major part of the USAF maintenance manpower determination process, should be capable of providing information on the relationship between the workcenter's performance and skill level effects. This thesis investigate...

R. Garcia J. P. Racher

1981-01-01

340

Incorporation of Competitive Effects in Forest Tree or Animal Breeding Programs  

PubMed Central

Competition among domesticated plants or animals can have a dramatic negative impact on yield of a stand or farm. The usual quantitative genetic model ignores these competitive interactions and could result in seriously incorrect breeding decisions and acerbate animal well-being. A general solution to this problem is given, for either forest tree breeding or penned animals, with mixed-model methodology (BLUP) utilized to separate effects on the phenotype due to the individuals' own genes (direct effects) and those from competing individuals (associative effects) and thereby to allow an optimum index selection on those effects. Biological verification was based on two lines of Japanese quail selected for 6-week weight; one line was selected only for direct effects (D-BLUP) while the other was selected on an optimal index for both direct and associative effects (C-BLUP). Results over 23 cycles of selection showed that C-BLUP produced a significant positive response to selection (b = 0.52 ± 0.25 g/hatch) whereas D-BLUP resulted in a nonsignificant negative response (b = ?0.10 ± 0.25 g/hatch). The regression of percentage of mortality on hatch number was significantly different between methods, decreasing with C-BLUP (b = ?0.06 ± 0.15 deaths/hatch) and increasing with D-BLUP (b = 0.32 ± 0.15 deaths/hatch). These results demonstrate that the traditional D-BLUP approach without associative effects not only is detrimental to response to selection but also compromises the well-being of animals. The differences in response show that competitive effects can be included in breeding programs, without measuring new traits, so that costs of the breeding program need not increase.

Muir, William M.

2005-01-01

341

Bacterial Surface Appendages Strongly Impact Nanomechanical and Electrokinetic Properties of Escherichia coli Cells Subjected to Osmotic Stress  

PubMed Central

The physicochemical properties and dynamics of bacterial envelope, play a major role in bacterial activity. In this study, the morphological, nanomechanical and electrohydrodynamic properties of Escherichia coli K-12 mutant cells were thoroughly investigated as a function of bulk medium ionic strength using atomic force microscopy (AFM) and electrokinetics (electrophoresis). Bacteria were differing according to genetic alterations controlling the production of different surface appendages (short and rigid Ag43 adhesins, longer and more flexible type 1 fimbriae and F pilus). From the analysis of the spatially resolved force curves, it is shown that cells elasticity and turgor pressure are not only depending on bulk salt concentration but also on the presence/absence and nature of surface appendage. In 1 mM KNO3, cells without appendages or cells surrounded by Ag43 exhibit large Young moduli and turgor pressures (?700–900 kPa and ?100–300 kPa respectively). Under similar ionic strength condition, a dramatic ?50% to ?70% decrease of these nanomechanical parameters was evidenced for cells with appendages. Qualitatively, such dependence of nanomechanical behavior on surface organization remains when increasing medium salt content to 100 mM, even though, quantitatively, differences are marked to a much smaller extent. Additionally, for a given surface appendage, the magnitude of the nanomechanical parameters decreases significantly when increasing bulk salt concentration. This effect is ascribed to a bacterial exoosmotic water loss resulting in a combined contraction of bacterial cytoplasm together with an electrostatically-driven shrinkage of the surface appendages. The former process is demonstrated upon AFM analysis, while the latter, inaccessible upon AFM imaging, is inferred from electrophoretic data interpreted according to advanced soft particle electrokinetic theory. Altogether, AFM and electrokinetic results clearly demonstrate the intimate relationship between structure/flexibility and charge of bacterial envelope and propensity of bacterium and surface appendages to contract under hypertonic conditions.

Francius, Gregory; Polyakov, Pavel; Merlin, Jenny; Abe, Yumiko; Ghigo, Jean-Marc; Merlin, Christophe; Beloin, Christophe; Duval, Jerome F. L.

2011-01-01

342

Implementing Standards-Based Assessment Effectively: Incorporating Discussion of Exemplars into Classroom Teaching  

ERIC Educational Resources Information Center

|Many universities are moving to greater use of standards-based assessment to support effective student learning. Implementing a standards-based approach includes involving academic staff in writing descriptions of standards for assessment tasks both to guide the marking process and clarify staff expectations for students. However, recent research…

Hendry, Graham D.; Armstrong, Susan; Bromberger, Nikki

2012-01-01

343

Mutagenic Effect of Radionuclides Incorporated into DNA of Drosophila Melanogaster. Progress Report, 1978-1979.  

National Technical Information Service (NTIS)

A significant difference in the mutation frequency of sex-linked recessive lethals was observed due to the position in the DNA molecule in which tritium decay occurred. This local effect of tritium decay is interpreted as being due to the transmutation of...

W. R. Lee

1979-01-01

344

Freezing around a vertical cylinder immersed in porous media incorporating the natural convection effect  

Microsoft Academic Search

The present paper analyses the freezing heat transfer on a cold cylinder immersed in a superheated liquid-saturated porous medium. The main emphasis of this paper is to clarify the effect of natural convection in the liquid phase on the freezing process. A mathematical model was developed, based on several reasonable assumptions for fluid flow in a liquid phase. The governing

C.-Y. Wang; C. Z. Wu; C. J. Tu; S. Fukusako

1991-01-01

345

Effects of aromatic plants incorporated as green manure on weed and maize development  

Microsoft Academic Search

A 2-year field experiment was conducted in northern Greece to study the mulch effects of seven annual [anise (Pimpinella anisum L.), sweet fennel (Foeniculum vulgare P. Mill.), sweet basil (Ocimum basilicum L.), dill (Anethum graveolens L.), coriander (Coriandrum sativum L.), parsley (Petroselinum crispum (P. Mill.) Nyman ex A.W. Hill) and lacy phacelia (Phacelia tanacetifolia Benth.)] and three perennial [mint (Mentha

K. V. Dhima; I. B. Vasilakoglou; Th. D. Gatsis; E. Panou-Philotheou; I. G. Eleftherohorinos

2009-01-01

346

Effect of sodium incorporation into CuInSe2 from first principles  

NASA Astrophysics Data System (ADS)

The presence of small amounts of sodium has been shown to improve the electronic performance of Cu(In,Ga)Se2 (CIGS) solar cells, but the origins of this effect have not yet been fully resolved. In this work, we have addressed the questions involving the role of sodium in CuInSe2 (CIS) using density-functional-theory-based calculations. We find no direct way how the creation of Na-related point defects in bulk CIS would enhance p-type conductivity. Instead, we demonstrate that Na reduces copper mass transport due to the capture of copper vacancies by NaCu defects. This finding provides an explanation for experimental measurements where the presence of Na has been observed to decrease copper diffusion. The suggested mechanism can also impede VCu-related cluster formation and lead to measurable effects on defect distribution within the material.

Oikkonen, L. E.; Ganchenkova, M. G.; Seitsonen, A. P.; Nieminen, R. M.

2013-08-01

347

Test Reference Years for engineering purposes - incorporating the Urban Heat Island effect  

NASA Astrophysics Data System (ADS)

In order to calculate the performance of technical systems, e.g. with respect to heating, cooling or ventilating buildings, the engineers require suitable atmospheric data sets. As a common procedure so called Test Reference Years (TRY) are employed for that purpose. These TRY are usually based on long-term measurements and observations at distinct weather stations. According to international rules weather stations are commonly placed in open terrain. So especially for cities the question of representativity has to be raised since the built-up urban areas might show considerably higher air temperatures (urban heat island) compared to the surrounding region. Here a method is presented which allows to assess the urban effect on the thermal regime. It uses parameters that can be easily accessed, e.g., the number of inhabitants. Thus the intensity of the urban warming can be quantified. Those parameters are briefly discussed and ways to implement the urban heat island effect in TRY datasets are shown.

Spekat, A.; Kreienkamp, F.; Wienert, U.; Enke, W.

2010-09-01

348

Effects of SiO x -incorporation hydrocarbons on the tibological properties of DLC films  

Microsoft Academic Search

The effects of hexamethylsiloxane (HMDSO) reactants are studied on the adhesion and tribological properties of DLC films deposited directly on steel and Cr substrates. A 13.56-MHz magnetically confined inductively coupled plasma (ICP) system has been applied to deposit diamond-like carbon films using CH4 and Si-containing hydrocarbon reactant with bipolar-pulsed substrate bias. The RF power is varied from 100 W to

Liang-Yih Chen; Franklin Chau-Nan Hong

2001-01-01

349

Effect of Straw Incorporation on 15N?Labeled Ammonium Nitrogen Uptake and Rice Growth  

Microsoft Academic Search

A greenhouse experiment was conducted to determine the effect of rice straw residue on growth and uptake of added N?labeled ammonium nitrogen (NH4?N) (3% N abundance at the rate of 150 kg N ha) by rice in Crowley silt loam soil (Typic Albaqualfs). Higher rates of rice straw addition had an adverse affect on plant growth from the first to sixth

Manoch Kongchum; R. D. DeLaune; Wayne H. Hudnall; Patrick K. Bollich

2007-01-01

350

Fatigue-damage evaluation for mild steel incorporating mean stress and overload effects  

Microsoft Academic Search

Successful estimation of the service life of a structure or component which is subjected to a complex history of loading,\\u000a depends on a suitable cumulative-damage summation technique. A general technique must be capable of predicting the effects\\u000a on fatigue life of geometry, mean stress or strain, occasional overloads or overstrains, frequency of cycling and environment.\\u000a As a contribution towards the

P. Watson; T. H. Topper

1972-01-01

351

Antioxidant Effects of Berry Phenolics Incorporated in Oil-in-Water Emulsions with Continuous Phase ?-Lactoglobulin  

Microsoft Academic Search

The purpose of this study was to evaluate the effects of berry phenolics, in this case, black currant (Ribes nigrum) anthocyanins and raspberry (Rubus idaeus) ellagitannins, in the presence of continuous phase ?-lactoglobulin (?-Lg), on the oxidative stability of Brij 35-stabilized\\u000a corn oil-in-water emulsions. The extent of lipid oxidation in emulsions was measured by determining the formation of lipid\\u000a hydroperoxides

Hanna Salminen; Marina Heinonen; Eric A. Decker

2010-01-01

352

Considerations for Incorporating Bioavailability in Effect-Directed Analysis and Toxicity Identification Evaluation  

Microsoft Academic Search

\\u000a In order to avoid a bias toward highly toxic but poorly bioavailable compounds in the effect-directed analysis (EDA) of soils\\u000a and sediments, approaches are discussed to consider bioavailability in EDA procedures. In parallel, complimentary approaches\\u000a for making toxicity identification evaluations (TIEs) more capable of performing high resolution fractionation, toxicant isolation\\u000a and identification are described. These approaches focus on three processes

Werner Brack; Robert M. Burgess

353

Cross-modulatory effects of clopidogrel and heparin on platelet and fibrin incorporation in thrombosis.  

PubMed

Pharmacologic inhibition of platelet activation and aggregation is a mainstay for reducing the incidence of arterial thrombosis, whereas anticoagulation is the primary approach for preventing the development of venous thrombosis. The effect of standard pharmacologic agents on their reciprocal vessel - anticoagulants on arterial thrombosis and platelet inhibitor on venous thrombosis - is relatively understudied. This study was designed to evaluate murine large-vessel arterial or venous thrombosis under conditions of either fibrin or platelet inhibition. In this study, heparin and clopidogrel were used as standard anticoagulant and platelet inhibitor, respectively, evaluating both large artery and vein thrombosis in mice, using in-vivo fluorescence imaging to simultaneously measure fibrin and platelet levels at the thrombus induction site. Heparin reduced both fibrin and platelet development in both arteries and veins, with stronger influences on fibrin accrual. Clopidogrel had a stronger effect in arteries, reducing both platelet and fibrin accumulation. Clopidogrel also reduced platelet accumulation with venous thrombosis, but the reductions in fibrin formation did not reach statistical significance. These findings illustrate the interactive role of platelet activity and coagulation in the development of large-vessel thrombosis, with inhibition of one thrombotic component showing profound effects on the other component in both arterial and venous thrombosis. PMID:23492917

Cooley, Brian C; Herrera, Anthony J

2013-09-01

354

Effect of different lipids and surfactants on formulation of solid lipid nanoparticles incorporating tamoxifen citrate  

PubMed Central

Tamoxifen Citrate (TC) is an estrogen receptor antagonist and drug of choice for hormone sensitive breast cancer. Solid Lipid Nanoparticles loaded with TC were prepared by High Shear Homogenization followed by Ultrasonication. The aim of the present work is to study the effect of four different Solid Lipids and three Surfactants on Formulation and Stability of SLN. They were characterized for Particle size, Polydispersity Index and Zeta Potential by Zetasizer Nano. SLN prepared by Solid Lipid Compritol 888 (Glyceryldibehenate) and Tween 80 (1%) showed desired Particle Size of 206.9 nm, PDI of 0.046 and Zeta Potential of 9.32 mV.

Upadhyay, S. U.; Patel, J. K.; Patel, V. A.; Saluja, A. K.

2012-01-01

355

Tillage and herbicide incorporation effects on residue cover, runoff, erosion, and herbicide loss  

Microsoft Academic Search

A natural rainfall study was conducted to evaluate the effect of tillage and herbicide application methods on crop residue cover, surface runoff volume, erosion, and herbicide losses with sediment and runoff water. Sediment, water, and three herbicides (atrazine [(6-chloro-N-ethyl)-N-(1-methylethyl-1,3,5 triazine)-2-4-diamine], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)], and cyanazine [2-{{4-chloro-6-(ethylamino)-1,3,4-triazin-2-yl}amino}-2-methylpropionitrile]) losses were measured from continuous corn runoff plots (1.7×12.0m long) in 1993 and 1994. Four

S. K Mickelson; P Boyd; J. L Baker; S. I Ahmed

2001-01-01

356

Electrokinetic removal of uranium from contaminated, unsaturated soils  

SciTech Connect

Electrokinetic remediation of uranium-contaminated soil was studied in a series of laboratory-scale experiments in test cells with identical geometry using quartz sand at approximately 10 percent moisture content. Uranium, when present in the soil system as an anionic complex, could be migrated through unsaturated soil using electrokinetics. The distance that the uranium migrated in the test cell was dependent upon the initial molar ratio of citrate to uranium used. Over 50 percent of the uranium was recovered from the test cells using the citrate and carbonate complexing agents over of period of 15 days. Soil analyses showed that the uranium remaining in the test cells had been mobilized and ultimately would have been extracted. Uranium extraction exceeded 90 percent in an experiment that was operated for 37 days. Over 70 percent of the uranium was removed from a Hanford waste sample over a 55 day operating period. Citrate and carbonate ligand utilization ratios required for removing 50 percent of the uranium from the uranium-contaminated sand systems were approximately 230 moles ligand per mole uranium and 1320 moles ligand per mole uranium for the waste. Modifying the operating conditions to increasing the residence time of the complexants is expected to improved the utilization efficiency of the complexing agent.

Booher, W.F. [IT Corp., Albuquerque, NM (United States); Lindgren, E.R.; Brady, P.V. [Sandia National Laboratories, Albuquerque, NM (United States)

1997-01-01

357

Increasing the Sensitivity of ELISA using Multiplexed Electrokinetic Concentrator  

PubMed Central

We developed a novel method to increase the sensitivity of standard Enzyme-Linked Immunosorbent Assay (ELISA) using a multiplexed electrokinetic concentration chip. The poly(dimethylsiloxane) (PDMS) molecular concentrator1 was used to trap and collect charged fluorescent product of target-bound enzyme turnover reaction of ELISA that occurred in a standard 96 well plate. Detection sensitivities of both Prostate Specific Antigen (PSA) and CA 19-9 (a human pancreatic and gastrointestinal cancer marker) ELISAs in serum are enhanced ~100 fold with a low CV of <17%. We also integrated this method with an on-chip bead-based ELISA that lends itself toward a fully-automated on-chip diagnostic device. Detection sensitivity of microfluidic bead-based CA 19-9 ELISA in serum is enhanced ~65 fold compared to the results without electrokinetic accumulation step. This chip can be directly applied to enhance the readout sensitivity of a wide range of existing ELISA kits at concentrations below the current detection limit.

Cheow, Lih Feng; Ko, Sung Hee; Kim, Sung Jae; Kang, Kwan Hyoung; Han, Jongyoon

2010-01-01

358

Amplified Electrokinetic Response Concentration Polarization near Nanofluidic Channel  

PubMed Central

Ion concentration polarization is the fundamental transport phenomenon that occurs near ion-selective membranes, but this important membrane phenomenon has been poorly understood due to theoretical and experimental challenges. Here, we report the first direct measurements of detailed flow and electric potential profiles within and near the depletion region. This work is an important step towards a full characterization of this coupled transport problem. Using microfabricated electrodes integrated with the microfluidic device, we measured and confirmed that the electric field inside an ion depletion region is amplified more than 30 fold compared to outside of the depletion zone due to the highly non-uniform ion concentration distribution along the microchannel. As a result, the electrokinetic motion of both fluid (electroosmosis) and particle (electrophoresis) was significantly amplified. The detailed flow profile within the depletion zone was also measured for the first time by optically tracking photobleached neutral dye molecules. We further showed that the amplified electrokinetic flows generated in this device may be used as a field-controlled, microfluidic fluid pump and switch.

Kim, Sung Jae; Li, Leon D.; Han, Jongyoon

2009-01-01

359

Microemulsion electrokinetic chromatography for analysis of phthalates in soft drinks.  

PubMed

Microemulsion electrokinetic chromatography (MEEKC) is proposed for analysis of di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) in soft drinks. However, the instability of microemulsion is a critical issue. In this research, a novel material, Pluronic® F-127, which has the properties of polymer and surfactant, was added for stabilizing the microemulsion in the MEEKC system. Our data demonstrate that the presence of Pluronic® F-127 (0.05-0.30%) also helps enhance resolution of highly hydrophobic compounds, DBP and DEHP. The electrokinetic injection of sodium dodecyl sulphate (SDS) including sample (-10kV, 20s) was introduced in this MEEKC system and this yielded about 25-fold sensitivity enhancement compared with hydrodynamic injection (1psi, 10s). During method validation, calibration curves were linear (r?0.99), within a range of 75-500ng/mL for DBP and 150-1000ng/mL for DEHP. As the precision and accuracy assays, absolute values of relative standard deviation (RSD) and relative error (RE) in intraday (n=3) and interday (n=5) observations were less than 4.93%. This method was further applied for analyzing six commercial soft drinks and one was found containing 453.67ng/mL of DEHP. This method is considered feasible for serving as a tool for analysis of highly hydrophobic molecules. PMID:23993511

Hsieh, Sung-Yu; Wang, Chun-Chi; Wu, Shou-Mei

2013-06-15

360

An AC electrokinetic impedance immunosensor for rapid detection of tuberculosis.  

PubMed

This work presents an AC electrokinetic impedance sensing method that is capable of detecting specific interactions between macromolecules such as antigen-antibody binding. Serum samples were added to the surface of interdigitated electrodes that had been coated with bacterial antigens. After applying an AC signal of 100 mV at a specific frequency continuously, the electrodes' impedance change was recorded and used to determine the occurrence and level of antibody binding to the antigen. Our theoretical analysis indicated that with this AC signal, the target macromolecules will experience a sufficiently strong attraction force towards the electrode surface for acceleration of the binding process. Using this method, 11 human tuberculosis and 10 bovine tuberculosis serum samples were tested. The results were consistent with those obtained by a conventional ELISA method. The limit of detection of the impedance sensing method was estimated to be better than 10 ng mL(-1). In summary, we demonstrate that AC electrokinetic impedance sensing can be used for rapid and sensitive detection of specific antibodies in serum samples. This method may form a basis for development of a point of care diagnostic device for human and bovine tuberculosis. PMID:24135732

Cui, Haochen; Li, Shanshan; Yuan, Quan; Wadhwa, Ashutosh; Eda, Shigetoshi; Chambers, Mark; Ashford, Roland; Jiang, Hongyuan; Wu, Jie

2013-12-01

361

Effect of incorporating low intensity exercise into the recovery period after a rugby match  

PubMed Central

Background: The psychological and physiological condition of athletes affect both their performance in competitions and their health. Rugby is an intense sport which appears to impose psychological and physiological stress on players. However, there have been few studies of the most appropriate resting techniques to deliver effective recovery from a match. Objectives: To compare the difference in recovery after a match using resting techniques with or without exercise. Methods: Fifteen Japanese college rugby football players were studied. Seven performed only normal daily activities and eight performed additional low intensity exercise during the post-match rest period. Players were examined just before and immediately after the match and one and two days after the match. Blood biochemistry and two neutrophil functions, phagocytic activity and oxidative burst, were measured to assess physiological condition, and the profile of mood states (POMS) scores were examined to evaluate psychological condition. Results: Immediately after the match, muscle damage, decreases in neutrophil functions, and mental fatigue were observed in both groups. Muscle damage and neutrophil functions recovered with time almost equally in the two groups, but the POMS scores were significantly decreased only in subjects in the low intensity exercise group. Conclusions: Rugby matches impose both physiological and psychological stress on players. The addition of low intensity exercise to the rest period did not adversely affect physiological recovery and had a significantly beneficial effect on psychological recovery by enhancing relaxation.

Suzuki, M; Umeda, T; Nakaji, S; Shimoyama, T; Mashiko, T; Sugawara, K

2004-01-01

362

Effect of Excipients on PLGA Film Degradation and the Stability of an Incorporated Peptide  

PubMed Central

The effect of pH modifying excipients on the chemical stability of a model peptide (VYPNGA) and the degradation of poly(DL-lactide-co-glycolide)(PLGA) was studied in PLGA films under accelerated storage conditions. pH modifiers included a basic amine (proton sponge), a basic salt (magnesium hydroxide) and two pH buffers (ammonium acetate and magnesium acetate). Changes in film pH were monitored using 13C NMR, peptide degradation products were quantified by LC/MS/MS and PLGA degradation was analyzed by TGA, DSC and SEC. Inclusion of pH modifiers had little impact on PLGA degradation. The proton sponge affected an initial decrease in pH but reduced peptide deamidation and chain cleavage relative to an unbuffered control. Magnesium hydroxide produced an initial increase in pH but also showed increased peptide deamidation. Ammonium acetate decreased pH and increased peptide chain cleavage, presumably due to increased PLGA hydrolysis. Magnesium acetate buffer increased the initial pH but resulted in increased peptide loss. The extent of peptide acylation increased in all formulations, most notably in the proton sponge modified films. The effectiveness of pH modifiers in PLGA formulations under storage conditions is dependant on both the mechanism of pH alteration and the peptide degradation reaction of interest.

Houchin, M.L.; Neuenswander, S.A.; Topp, E.M.

2007-01-01

363

Incorporating Duplicate Genotype Data into Linear Trend Tests of Genetic Association: Methods and Cost-Effectiveness  

PubMed Central

The genome-wide association (GWA) study is an increasingly popular way to attempt to identify the causal variants in human disease. Duplicate genotyping (or re-genotyping) a portion of the samples in a GWA study is common, though it is typical for these data to be ignored in subsequent tests of genetic association. We demonstrate a method for including duplicate genotype data in linear trend tests of genetic association which yields increased power. We also consider the cost-effectiveness of collecting duplicate genotype data and find that when the relative cost of genotyping to phenotyping and sample acquisition costs is less than or equal to the genotyping error rate it is more powerful to duplicate genotype the entire sample instead of spending the same money to increase the sample size. Duplicate genotyping is particularly cost-effective when SNP minor allele frequencies are low. Practical advice for the implementation of duplicate genotyping is provided. Free software is provided to compute asymptotic and permutation based tests of association using duplicate genotype data as well as to aid in the duplicate genotyping design decision.

Borchers, Bryce; Brown, Marshall; McLellan, Brian; Bekmetjev, Airat; Tintle, Nathan L

2009-01-01

364

Incorporation in lipid microparticles of the UVA filter, butyl methoxydibenzoylmethane combined with the UVB filter, octocrylene: effect on photostability.  

PubMed

The aim of this study was to reduce the photoinstability of butyl methoxydibenzoylmethane (BMDBM), the most widely used UVA filter, by incorporating it in lipid microparticles (LMs) alone or together with the UVB filter octocrylene (OCR), acting also as photostabilizer. Microparticles loaded with BMDBM or with combined BMDBM and OCR were produced by the hot emulsion technique, using glyceryl behenate as lipid material and poloxamer 188 as surfactant. The LMs were characterized by release studies, scanning electron microscopy, and powder X-ray diffractometry. The BMDBM and OCR loading was 15.2% and 10.6%, respectively. In order to reproduce the conditions prevalent in commercial sunscreen products, the photoprotective efficacy of the LMs was evaluated after their introduction in a model cream (oil-in-water emulsion) containing a mixture of UVA and UVB filters. A small but statistically significant decrease in BMDBM photodegradation was obtained when the UVA filter was encapsulated alone into the LMs (the extent of degradation was 28.6% +/-2.4 for non-encapsulated BMDBM and 26.0% +/-2.5 for BMDBM-loaded microparticles). On the other hand, the co-loading of OCR in the LMs produced a more marked reduction in the light-induced decomposition of microencapsulated BMDBM (the UVA filter loss was 21.5% +/-2.2). Therefore, incorporation in lipid microparticles of BMDBM together with the sunscreen OCR is more effective in enhancing the UVA filter photostability than LMs loaded with BMDBM alone. PMID:19381836

Scalia, Santo; Mezzena, Matteo

2009-04-21

365

A compact model for tunnel field-effect transistors incorporating nonlocal band-to-band tunneling  

NASA Astrophysics Data System (ADS)

To enable circuit design using tunnel field-effect transistors (TFETs), a physics-based model based on nonlocal band-to-band tunneling is developed. To maintain accuracy, the tunneling lengths are estimated assuming that both vertical and horizontal tunneling paths exist in the device. The static current-voltage characteristics are modeled, including the diode currents and Esaki tunneling. Parasitic capacitances and resistances are included to enable transient circuit analyses. The model is validated by comparison with measurements of silicon TFETs, as well as with semiconductor device simulations based on nonlocal band-to-band tunneling. The model accounts for TFET behavior in circuits, as demonstrated by simulations of inverters and static random access memories. Consequently, the model can be used to develop TFET circuits for low-power applications.

Fukuda, K.; Mori, T.; Mizubayashi, W.; Morita, Y.; Tanabe, A.; Masahara, M.; Yasuda, T.; Migita, S.; Ota, H.

2013-10-01

366

A Backscattering Model Incorporating the Effective Carrier Temperature in Nano-MOSFET  

NASA Astrophysics Data System (ADS)

In this work we propose a channel backscattering model in which increased carrier temperature at the top of the potential energy barrier in the channel is taken into account. This model represents an extension of a previous model by the same authors which highlighted the importance of considering the partially ballistic transport between the source contact and the top of the potential energy barrier in the channel. The increase of carrier temperature is precisely due to energy dissipation between the source contact and the top of the barrier caused by the high saturation current. To support our discussion, accurate 2D full band Monte Carlo device simulations with quantum correction have been performed in double gate nMOSFETs for different geometries (gate length down to 10 nm), biases and lattice temperatures. Including the effective carrier temperature is especially important to properly treat the high inversion regime, where previous backscattering models usually fail.

Giusi, Gino; Iannaccone, Giuseppe; Crupi, Felice; Ravaioli, Umberto

2011-07-01

367

The effects of iron oxide incorporation on the chondrogenic potential of three human cell types  

PubMed Central

Non-invasive monitoring of living cells in vivo provides an important tool in the development of cell-based therapies in cartilage tissue engineering. High-resolution magnetic resonance imaging (MRI) has been used to monitor target cell populations in vivo. However, the side-effects on cell function of the labelling reagents, such as superparamagnetic iron oxide (SPIO), are still unclear. This study investigated the effect of SPIO particles on the chondrogenic differentiation of human bone marrow stromal cells (HBMSCs), neonatal and adult chondrocytes in vitro. Cells were labelled with SPIO for 24 h and chondrogenesis induced in serum-free medium including TGF?3. For labelled/unlabelled cells, viability, morphology and proliferation were determined using CellTracker™ Green and PicoGreen dsDNA assays. The expression of SOX9, COL2A1 and ACAN was investigated using qRT–PCR after 2, 7 and 14 days. The results showed that viability was unaffected in all of the cells but cell morphology changed towards a 'stretched' phenotype following SPIO uptake. Cell proliferation was reduced only for labelled neonatal chondrocytes. SOX9 and COL2A1 expression decreased at day 2 but not at days 7 and 14 for labelled HBMSCs and adult chondrocytes; ACAN expression was unaffected. In contrast, SOX9 and COL2A1 expression were unaffected in labelled neonatal chondrocytes but a decrease in ACAN expression was seen at day 14. The results suggest that downregulation of chondrogenic genes associated with SPIO labelling is temporary and target cell-dependent. Resovist® can be used to label HBMSCs or mature chondrocytes for MR imaging of cells for cartilage tissue engineering. Copyright © 2012 John Wiley & Sons, Ltd.

Saha, Sushmita; Yang, Xuebin B; Tanner, Steven; Curran, Stephen; Wood, David; Kirkham, Jennifer

2013-01-01

368

Linking flood frequency to long-term water balance: Incorporating effects of seasonality  

NASA Astrophysics Data System (ADS)

Derived flood frequency models can be used to study climate and land use change effects on the flood frequency curve. Intra-annual (i.e., within year) climate variability strongly impacts upon the flood frequency characteristics in two ways: in a direct way through the seasonal variability of storm characteristics and indirectly through the seasonality of rainfall and evapotranspiration which then affect the antecedent catchment conditions for individual storm events. In this paper we propose a quasi-analytical derived flood frequency model that is able to account for both types of seasonalities. The model treats individual events separately. It consists of a rainfall model with seasonally varying parameters. Increased flood peaks, as compared to block rainfall, due to random within-storm rainfall time patterns are represented by a factor that is a function of the ratio of storm duration and catchment response time. Event runoff coefficients are allowed to vary seasonally and include a random component. Their statistical characteristics are derived from long-term water balance simulations. The components of the derived flood frequency model are integrated in probability space to derive monthly flood frequency curves. These are then combined into annual flood frequency curves. Comparisons with Monte Carlo simulations using parameters that are typical of Austrian catchments indicate that the approximations used here are appropriate. We perform sensitivity analyses to explore the effects of the interaction of rainfall and antecedent soil moisture seasonalities on the flood frequency curve. When the two seasonalities are in phase, there is resonance, which increases the flood frequency curve dramatically. We are also able to isolate the contributions of individual months to the annual flood frequency curve. Monthly flood frequency curves cross over for the parameters chosen here, as extreme floods tend to mainly occur in summer while less extreme floods may occur throughout the year.

Sivapalan, M.; BlöSchl, G.; Merz, R.; Gutknecht, D.

2005-06-01

369

Incorporating Kinetic Effects into Global Models of the Solar Wind (Invited)  

NASA Astrophysics Data System (ADS)

The origins of the hot solar corona and the supersonically expanding solar wind are still the subject of much debate. Far from there being a shortage of ideas, there is in fact a surplus of proposed physical mechanisms, each of which requires testing by comparison with observations. This process is difficult not only because the empirical measurements are limited, but also because many of the proposed mechanisms act on a wide range of spatial scales (from centimeters to solar radii) with feedback effects that are not yet well understood. Many of these mechanisms are related to the dissipation of solar MHD waves, and many involve multiple steps of energy conversion between waves, turbulence, current sheets, and other nonlinear plasma features. This presentation will give a summary of wave/turbulence models that seem to succeed in explaining the time-steady properties of the corona and the existence of fast and slow solar wind streams. A new global model of nonlinear MHD wave transport and dissipation in polar coronal holes, which includes both compressible and incompressible fluctuations, will also be presented. The goal of this model is to predict the kinetic partitioning of heat deposition between electrons, protons, and heavy ions, with as few free parameters as possible.

Cranmer, S. R.

2010-12-01

370

Incorporating retrospective clustering into a prospective Cusum methodology for anthrax: evaluating the effects of disease expectation.  

PubMed

We analysed livestock anthrax in Kazakhstan from 1960-2006, using a prospective CUSUM to examine the affects of expectation on the detection of spatio-temporal clusters. Three methods for deriving baselines were used for CUSUM; a standard z-score, AVG, a spatially-weighted z-score derived from Local Moran's I, LISA, and a moving-window average, MWA. LISA and AVG elicited alarm signals in the second year that did not return below threshold during the 47-year period, while MWA signaled an alarm at year four and relented at year fifteen. The number of spatial clusters elicited varied: LISA n=16, AVG n=11, and MWA n=3, although there were clusters present around Shymkent, in south-central Kazakhstan, in each method. The results illustrate that the selection of a baseline with an unknown background population has a significant effect on the ability to detect the onset of clusters in space and in time when employing a CUSUM methodology. PMID:22749547

Kracalik, Ian; Lukhnova, Larissa; Aikimbayev, Alim; Pazilov, Yerlan; Temiralyeva, Gulnara; Blackburn, Jason K

2010-06-25

371

Incorporating what promotoras learn: becoming role models to effect positive change.  

PubMed

Promotoras (community health workers) play an important health promotion role and must be continuously trained, but little is known about how much of their learning they actually put into practice. This non-randomized, longitudinal study examined knowledge and home environmental outcomes of an asthma and healthy homes training offered to promotoras using a train-the-trainer model. Eighty-five promotoras received the training and pre- and post-test surveys were used to measure training outcomes. Results showed a statistically significant increase in asthma and healthy home-related knowledge (P < .001). At 12-months post-intervention, a majority of the promotoras (69%) reported they made household changes to improve their indoor environment as a result of the training. This study suggests that effective trainings can improve promotoras knowledge and behaviors for the promotion of healthy homes in the community. Further evaluation is needed to investigate whether these trainings allow promotoras to serve as role models within their communities "by educating through example" and thereby enhance their credibility as health educators. PMID:22160747

Lucio, Rose L; Zuniga, Genny Carrillo; Seol, Yoon-Ho; Garza, Norma; Mier, Nelda; Trevino, Laura

2012-10-01

372

Effect of Cr2O3 on the 18O Tracer Incorporation in SOFC Materials  

SciTech Connect

Investigations of the impact of Cr{sub 2}O{sub 3} overlayers on the oxygen self diffusion in two SOFC materials were conducted to gain insight into the Cr poisoning mechanism at the cathode side of solid oxide fuel cells (SOFCs) with stainless steel interconnects. High density Y{sub 0.15}Zr{sub 0.85}O{sub 2} (YSZ) and La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF) sintered pellets were covered with 3 to 30 nm Cr overlayers that were subsequently oxidized, forming Cr{sub 2}O{sub 3}. Standard {sup 18}O tracer diffusion experiments at 800 C were performed and ToF-SIMS profiling revealed that the oxygen ion diffusion coefficients were unaffected by the thin Cr{sub 2}O{sub 3} overlayers, which is predictable since they are a bulk property, but the extracted effective surface exchange coefficients varied with Cr{sub 2}O{sub 3} overlayer thickness. Solid-state reaction measurements and electronic structure considerations concerning the surface exchange, led to the conclusion that the observed oxygen uptake hindrance for Cr{sub 2}O{sub 3} capped LSCF and the slight increase of the surface exchange coefficient for Cr{sub 2}O{sub 3} capped YSZ can be attributed to the electronic properties of Cr{sub 2}O{sub 3}. A critical thickness for Cr{sub 2}O{sub 3} was determined to be 12 nm where the transition from decreasing cathode-performance to a Cr{sub 2}O{sub 3}-property-governed regime occurs.

Finsterbusch, M.; Lussier, A; Negusse, E; Zhu, Z; Smith, R; Schaefer, J; Idzerda, Y

2010-01-01

373

Effect of incorporation of drugs, vitamins and peptides on the structure and dynamics of lipid assemblies.  

PubMed

The characteristics of vesicles formed from Dipalmitoyl Phosphatidyl Choline (DPPC) are sensitive to the presence of perturbing molecules such as drugs, peptides, hormones and vitamins. We have used ESR spin labeling and NMR techniques for studying interaction of such molecules with lipid bilayers. ESR spin labeling has been used to monitor thermotropic behaviour of model membranes. Different NMR probes such as 1H, 31P, 13C have been used to gather information regarding the mode of interaction. It has been observed that the model membrane systems respond differently depending upon the localization of the perturbing molecules in the lipid bilayer. Small molecules such as neurotransmitters epinephrine and norepinephrine decrease gel to liquid crystalline phase transition temperature significantly even when present in small amounts. Vitamin E acetate having a hydrophobic hydrocarbon tail orients parallel to the lipid molecule and thereby exhibits dynamics similar to palmitate chain. When the acetate group is replaced by hydroxyl group (alpha-tocopherol), the phase transition becomes broad and the lipid molecules loose freedom of lateral diffusion. This can be attributed to formation of hydrogen bond between the hydroxyl group of alpha-tocopherol and phosphate moiety of lipid. The conformation of antidepressants nitroxazepine and imipramine is significantly altered when embedded in lipid bilayer. Anaesthetic etomidate not only modifies thermotropic characteristics but also induces polymorphism. The normal bilayer arrangement of lipids gets transformed into hexagonal packing. Amino acid tryptophan induces cubic phases in the normal bilayer arrangement of DPPC dispersions. Peptide gonadoliberin shows a reduced internal motion due to the lipid peptide interaction. The major consequences of binding of lipids with externally added molecules are changes in the fluidity and permeability properties of membranes. It has been shown that permeability is effected by the presence of molecules such as propranolol, alpha-tocopherol and its analogue, neurotransmitters, etc. The magnetic resonance methods have thus evolved as power techniques in the study of membrane structure and function. PMID:2695835

Srivastava, S; Phadke, R S; Govil, G

374

SANDIA NATIONAL LABORATORIES IN SITU ELECTROKINETIC EXTRACTION TECHNOLOGY; INNOVATIVE TECHNOLOGY EVALUATION REPORT  

EPA Science Inventory

As a part of the Superfund Innovative Technology Evaluation (SITE) Program, the U.S. Environmental Protection Agency evaluated the In-Situ Electrokinetic Extraction (ISEE) system at Sandia National Laboratories, Albuquerque, New Mexico. The SITE demonstration results show ...

375

Bile salt surfactants in micellar electrokinetic capillary chromatography: Application to hydrophobic molecule separations.  

National Technical Information Service (NTIS)

Bile Salt surfactants are used in the micellar electrokinetic capillary chromatography (MECC) separation of various hydrophobic compounds. The use of methanol in the mobile phase allows the separation of previously intractable compounds including polyarom...

R. O. Cole M. J. Sepaniak W. L. Hinze J. Gorse K. Oldiges

1990-01-01

376

Development and applications of micellar electrokinetic capillary chromatography. [Pyridoxic acid in urine  

SciTech Connect

The experimental parameters affecting efficiency and selectivity in micellar electrokinetic capillary chromatography (MECC) were investigated. Its use to separate the metabolites of vitamin B/sub 6/ and to determine pyridoxic acid in urine is also presented.

Burton, D.E.

1986-03-01

377

ENANTIOSEPARATION OF MALATHION, CRUFORMATE, AND FENSULFOTHION ORGANOSPHOSPHORUS PESTICIDES BY MIXED-MODE ELECTROKINETIC CAPILLARY CHROMATOGRAPHY  

EPA Science Inventory

Mixed-mode electrokinetic capillary chromatography (mixed-ECC) has been used for the enantioseparation of organophosphorus pesticides. In mixed-ECC, a combination of three pseudostationary phases including surfactants, neutral, and charged cyclodextrins, are used to resolve very ...

378

A method for measuring electrokinetic coefficients of porous media and its potential application in hydrocarbon exploration  

NASA Astrophysics Data System (ADS)

We have designed and constructed a compact cell to measure the electrokinetic coefficients in the frequency range of interest to hydrocarbon exploration, 20 to 100 Hz. Experimental results are presented on the frequency dependence of the electrokinetic coefficients, and dynamic permeability of a porous rock saturated with either 0.1 mole brine or transformer oil. In particular, the brine-saturated electro-osmosis coefficient is found to be two orders of magnitude larger than that saturated with transformer oil; whereas for the streaming potential the ratio of the two cases is in the reverse. These results, when combined with viscosity and electrical conductivity values, lead consistently to the fact that the electrokinetic Onsager coefficient of brine-saturated samples is three orders of magnitude larger than that of oil-saturated samples. This difference provides a strong motivation to further explore the potential application of electrokinetic Onsager coefficient as a hydrocarbon indicator.

Jiang, Y. G.; Shan, F. K.; Jin, H. M.; Zhou, L. W.; Sheng, Ping

379

Enhanced electrokinetic manipulation and impedance sensing using FPGA digital signal processing  

Microsoft Academic Search

Electrokinetic manipulation of microscopic biological particles, such as bacteria and other cells, is useful in the technology of lab-on-a-chip devices and micro-total-analysis systems (muTAS). In electrokinetic manipulation, non-uniform electric fields are used to exploit the dielectric properties of suspended biological microparticles, to induce forces and torques on the particles. The electric fields are produced by planar electrode arrays patterned on

Steven N. Higginbotham; Denis R. Sweatman

2006-01-01

380

Electroosmosis and pore pressure development characteristics in lead contaminated soil during electrokinetic remediation  

Microsoft Academic Search

Physical and chemical reactions occur during the electrokinetic treatment. When an electric current was applied to soil for\\u000a some duration, fluid transport phenomena occurred in the soil-water system and the characteristics of soil-water interface\\u000a varied according to the pH levels due to electrolysis. In addition, reactions occurring within the electrokinetic system are\\u000a changed according to the inter-reactions of the clay

Sang-Jae Han; Soo-Sam Kim; Byung-Il Kim

2004-01-01

381

A two-scale non-local model of swelling porous media incorporating ion size correlation effects  

NASA Astrophysics Data System (ADS)

A new two-scale model is proposed for derivation of the macroscopic modified effective stress principle for swelling porous media saturated by an electrolyte solution containing finite size ions. A non-local pore-scale model is developed within the framework of Statistical Mechanics in conjunction with the thermodynamic approach based on Density Functional Theory leading to a nonlinear integral Fredholm equation of second kind for the ion/nanopore correlation function coupled with Poisson problem for the electric double layer potential. When combined with the fluid equilibrium condition such non-local electrochemical problem gives rise to a constitutive law for the fluid stress tensor in terms of the disjoining pressure which is decomposed into several components of different nature. The homogenization procedure based on formal asymptotic expansions is applied to up-scale the model to the macroscale leading to a two-scale constitutive law for the swelling pressure appearing in the modified effective stress principle with improved accuracy incorporating the deviations from the Gouy–Chapman Poisson–Boltzmann-based theory due to the finite size short-range ion–ion correlation effects. The integro-differential problem posed in a periodic cell is discretized by collocation schemes. Numerical results are obtained for a stratified arrangement of parallel macromolecules showing that the effects of ion–ion correlation forces give rise to anomalous attraction patterns between the particles for divalent ions.

Le, T. D.; Moyne, C.; Murad, M. A.; Lima, S. A.

2013-12-01

382

Development of an integrated, in-situ remediation technology: Task 2--4, electrokinetic modeling. Topical report, September 26--May 25, 1996  

SciTech Connect

This report summarizes the work conducted in Tasks 2-4, which together make up the Electrokinetic Modeling carried out in this project. The modeling was divided into three main sections: thermal analysis, chemical species transport, and electrode geometry and soil heterogeneity issues. The thermal modeling consisted of development of the governing equations to incorporate Joule heating associated with electro-osmosis, heat conduction and convection, and temperature dependencies of electrical conductivity and electro-osmotic permeability. To model the transport of chemical species in the Lasagna{sup TM} process, a one-dimensional model was developed. This model is based on previous models, but includes additional mechanism to account for charge transfer in the double layer, pH buffering of the soil, and zeta potential dependency on pH and ionic strength. The results of this model and the corroboration by experimental measurement support some key assumptions made in the thermal model. An analysis was also conducted to compare the use of cylindrical electrodes to the plate geometry used in Phase I. In summary, cylindrical electrodes may be appropriate for anodes, because the do not intercept the flow. If used as cathodes, a planar treatment zone in their vicinity would probably be required. The cylindrical electrodes can operate at reasonable current densities without boiling water. Because the hottest region is at the electrode, cooling schemes could be used to operate at higher current densities. If iron anodes are used, they will have to be quite massive, and may not be economical compared to planar models. An example of soil heterogeneity was investigated when it was discovered that a steel pt was buried in the vicinity of the pilot test. There is some distortion of the field near the pit, but its effects on the test zone between the electrodes are minimal.

NONE

1997-05-01

383

Enhanced electrokinetic manipulation and impedance sensing using FPGA digital signal processing  

NASA Astrophysics Data System (ADS)

Electrokinetic manipulation of microscopic biological particles, such as bacteria and other cells, is useful in the technology of lab-on-a-chip devices and micro-total-analysis systems (?TAS). In electrokinetic manipulation, non-uniform electric fields are used to exploit the dielectric properties of suspended biological microparticles, to induce forces and torques on the particles. The electric fields are produced by planar electrode arrays patterned on electrically-insulating substrates. Biological microparticles are dielectrically-heterogeneous structures. Each different type of biological cell has a distinct dielectric frequency response signature. This dielectric distinction allows specificity when manipulating biological microparticles using electrokinetics. Electrokinetic microbiological particle manipulation has numerous potential applications in biotechnology, such as the separation and study of cancerous cells, determining the viability of cells, as well as enabling more automation and parallelization in microbiological research and pathology. This paper presents microfabricated devices for the manipulation of biological microparticles using electrokinetics. Methods of impedance sensing for determining microparticle concentration and type are also discussed. This paper also presents methods of using digital signal processing systems to enhance the manipulation and sensing of the microbiological particles. A Field-Programmable Gate Array (FPGA) based system is demonstrated which is used to digitally synthesize signals for electrokinetic actuation, and to process signals for impedance sensing.

Higginbotham, Steven N.; Sweatman, Denis R.

2006-01-01

384

Can an electro-kinetic mechanism explain artificial earthquakes?  

NASA Astrophysics Data System (ADS)

Researchers of the Joint Institute for High Temperatures of the Russian Academy of Sciences have carried out a large number of current injection experiments using a 4.2 km long dipole at the Bishkek Research Station in the Chu valley area of the Kyrgyz mountains (northern Tien Shan). The current is generated using Pulsed Magneto-Hydrodynamic (MHD) generators that can produce 2800 amperes at 1350 volts for up to 12.1 seconds. They have found that the number of earthquakes in the region within 150 km of the injection site increased by over 10 standard deviations of the background seismicity. The probability of this occurring by chance is only one in every thousand million million (10^15) measurements. It is certain, therefore, that we can generate earthquakes by current injection. However, no satisfactory physical mechanism for it currently exists. Paul Glover has suggested that an electro-kinetic mechanism may be the missing causal link. In his theory the injected current creates a three-dimensional electric field in the subsurface. The electro-kinetic mechanism uses the electric field to move the pore fluid at depth. If the pore fluid flows into a fault zone it may accumulate and transiently raise the pore fluid pressure within the fault zone. It is known that increases of pore fluid pressure within fault zones more than a critical pressure of 0.05 MPa are sufficient to trigger an earthquake if the fault has sufficient accumulated strain. Earthquakes are therefore possible while the pore fluid pressure is over the critical pressure. While the electro-kinetic drive has been well studied around the world, it is uncertain if the mechanism can provide fluid pressures sufficient to trigger earthquakes up to 150 km from the injection point. In this work we present two dimensional numerical modelling of the proposed coupled mechanism using a finite element approach and using the software package Comsol Multiphysics. The initial results are promising and indicate that (i) transient pressures greater than the critical pressure can be easily generated by the mechanism, (ii) the transient pressures in the model farther than 200 m from the electrodes can take values of up to 2 MPa (40 times the critical value), (iii) the transient pressures remain above the critical value up to 160 km from the dipole, which is consistent with the range of the field experiments. However, the modelling has only been able to generate the transient pressures quasi-instantaneously. There is a clear delay in the field experiment data of two days between current injection and earthquake occurrence. We cannot currently account for this in our modelling, although research is continuing.

Cyr, Guillaume; Glover, Paul; Novikov, Victor

2010-05-01

385

Electrokinetic Flow and Dispersion in Capillary Electrophoresis  

NASA Astrophysics Data System (ADS)

Electrophoretic separation of a mixture of chemical species is a fundamental technique of great usefulness in biology, health care, and forensics. In capillary electrophoresis (which has evolved from its predecessor, slab-gel electrophoresis), the sample migrates through a single microcapillary instead of through the network of pores in a gel. A fundamental design problem is to minimize dispersion in the separation direction. Molecular diffusion is inevitable and sets a theoretical limit on the best separation that can be achieved. But in practice, there are a number of effects arising out of the interplay between fluid flow, chemistry, thermal effects, and electric fields that result in enhanced dispersion. This paper reviews the subject of fluid flow in such capillary microchannels and examines the various causes of enhanced dispersion that limit the efficiency of separation.

Ghosal, Sandip

2006-01-01

386

Evaluation of a dual-cyclodextrin phase variant of capillary electrokinetic chromatography for separations of nonionizable solutes  

SciTech Connect

A capillary electrokinetic chromatography technique is described that employs neutral cyclodextrins (CDs) as a primary phase, transported with electroosmotic flow, and charged CDs as an electrophoretically mediated secondary phase. Neutral, hydrophobic solutes are separated on the basis of their differential distribution between these CD phases. The technique resembles micellar electrokinetic capillary chromatography (MECC) with regard to instrumentation and the fundamental relationships for resolution and capacity factor, which are influenced by the existence of a finite elution window. Conversely, the CD technique offers unique and beneficial characteristics when compared to MECC. Efficiency, selectivity, and system retention are evaluated on the basis of separations of polyaromatic hydrocarbons (PAHs). Efficiency is comparable to that of MECC (> 10{sup 5} plates/m). The specificity associated with solute-CD inclusion complexation provides elution orders for PAHs that do not follow the hydrophobicity trends of MECC. Moreover, since the CD phases are largely noninteractive, complex CD systems can be used to enhance selectivity. Capacity factors can be altered in a convenient and predictable fashion simply by changing the CD phase ratio. The technique is rather robust with regard to the use of running buffers containing organic solvents; the effects or organic modifier and pH on system retention are demonstrated. 19 refs., 4 figs., 1 tab.

Sepaniak, M.J.; Copper, C.L.; Whitaker, K.W.; Anigbogu, V.C. [Univ. of Tennessee, Knoxville, TN (United States)

1995-07-01

387

A combination of electrokinetics and Pd/Fe PRB for the remediation of pentachlorophenol-contaminated soil.  

PubMed

Electrokinetic (EK) remediation of pentachlorophenol (PCP)-contaminated soil is difficult because PCP dissociates at different pH values along soil column and shows different transport behaviors near anode and cathode. In the present study, a permeable reactive barrier (PRB) filled with reactive Pd/Fe particles was installed between anode and cathode to reach the dechlorination of PCP during its EK movement. When PRB was installed at the position of 0.3 (normalized distance from anode), PCP in the section from anode to PRB could transport through PRB, while PCP in the section from cathode to PRB was accumulated near PRB. PCP was hardly dechlorinated by PRB wherein high pH was reached. When PRB was installed at the position of 0.5 and the pH in the PRB was decreased by periodical injection of HAc, 49% of PCP was removed, and 22.9% was recovered as phenol which was mostly collected in catholyte. The mechanism of PCP removal was proposed as the EK movement of PCP into the PRB compartment, the complete dechlorination of PCP to phenol by Pd/Fe in the PRB compartment, and the subsequent removal of phenol by electroosmosis. This study proved that the combination of electrokinetics and Pd/Fe PRB was effective for the remediation of PCP-contaminated soil. PMID:21470711

Li, Zhirong; Yuan, Songhu; Wan, Jinzhong; Long, Huayun; Tong, Man

2011-03-21

388

Mechanistic studies of partial-filing micellar electrokinetic chromatography  

SciTech Connect

The need for coupling micellar electrokinetic chromatography (MEKC) with electrospray mass spectrometry initiates the development of partial-filling MEKC. In comparison with conventional MEKC, only a small portion of the capillary is filled with a micellar solution for performing the separation in partial-filling MEKC. Analytes first migrate into the micellar plug, where the separation occurs, and then into the leading electrophoresis buffer, which is free of surfactants. A theoretical model is proposed for predicting the separation behavior of triazine herbicides in partial-filling MEKC. The comparisons between conventional and partial-filling MEKC in terms of separation efficiency and resolution of triazine herbicides are presented and discussed. The optimization techniques, possible applications, and advantages of partial-filling MEKC are similarly addressed. 11 refs., 6 figs., 5 tabs.

Nelson, W.M.; Lee, C.S. [Ames National Lab., IA (United States)]|[Iowa State Univ., Ames, IA (United States)

1996-09-15

389

Ferritization treatment of copper in soil by electrokinetic remediation.  

PubMed

The usefulness of the combined use of the electrokinetic (EK) remediation and a ferrite treatment zone (FTZ) was demonstrated for a treatment of the contaminated soil with heavy metal ions. Copper ions in contaminated soil were transferred into the FTZ by the EK technology and were ferritized in this system. The distribution of copper in a migration chamber after EK treatment with FTZ for 48h showed the large difference in the total and eluted concentration of copper. This indicated that copper ions transferred by EK into the FTZ were ferritized there with ferrite reagent in soil alkalified by EK process. The copper-ferrite compound, which was not dissolved with diluted acid, was retained in the FTZ and accumulated there. The ratio of the ferritized amount of copper against total copper was 92% in the EK process with FTZ after 48 h. PMID:17374444

Kimura, Tomoyuki; Takase, Ken-Ichi; Terui, Norifumi; Tanaka, Shunitz

2007-01-09

390

Cyclodextrin-mediated enantioseparation in microemulsion electrokinetic chromatography.  

PubMed

Chiral separation by means of cyclodextrins has a long-standing tradition in capillary electrophoresis techniques. Here we present a chiral method utilizing the recently introduced microemulsion electrokinetic chromatography. The microemulsion consisting of 1.0% SDS, 4.0% 1-butanol, 3.0% 2-propanol, 0.5% ethylacetate, and 91.5% 20 mM phosphate buffer pH 2.5 serves as a pseudostationary phase which is complemented by sulfated cyclodextrin as a second phase. The analytes partition between the aqueous running buffer and both pseudostationary phases, the oil droplets and the cyclodextrins. Enantiomers are separated due to the formation of transient diastereomeric complexes with the cyclodextrins. For the racemates of ephedrine derivatives studied here sulfated ?-cyclodextrin was successfully applied. The method is appropriate to resolve an entire series of chiral phenethylamines and can be used for separation of the racemates and impurity profiling, e.g., the determination of the enantiomeric excess. PMID:23283790

Borst, Claudia; Holzgrabe, Ulrike

2013-01-01

391

Electrokinetic-enhanced phytoremediation of soils: Status and opportunities.  

PubMed

Phytoremediation is a sustainable process in which green plants are used for the removal or elimination of contaminants in soils. Both organic and inorganic contaminants can be removed or degraded by growing plants by several mechanisms, namely phytoaccumulation, phytostabilization, phytodegradation, rhizofiltration and rhizodegradation. Phytoremediation has several advantages: it can be applied in situ over large areas, the cost is low, and the soil does not undergo significant damages. However, the restoration of a contaminated site by phytoremediation requires a long treatment time since the remediation depends on the growth and the biological cycles of the plant. It is only applicable for shallow depths within the reach of the roots, and the remediation efficiency largely depends on the physico-chemical properties of the soil and the bioavailability of the contaminants. The combination of phytoremediation and electrokinetics has been proposed in an attempt to avoid, in part, the limitations of phytoremediation. Basically, the coupled phytoremediation-electrokinetic technology consists of the application of a low intensity electric field to the contaminated soil in the vicinity of growing plants. The electric field may enhance the removal of the contaminants by increasing the bioavailability of the contaminants. Variables that affect the coupled technology are: the use of AC or DC current, voltage level and mode of voltage application (continuous or periodic), soil pH evolution, and the addition of facilitating agents to enhance the mobility and bioavailability of the contaminants. Several technical and practical challenges still remain that must be overcome through future research for successful application of this coupled technology at actual field sites. PMID:23835413

Cameselle, Claudio; Chirakkara, Reshma A; Reddy, Krishna R

2013-07-05

392

Multiplexed electrokinetic sample fractionation, preconcentration and elution for proteomics.  

PubMed

Both 6 and 8-channel integrated microfluidic sample pretreatment devices capable of performing "in space" sample fractionation, collection, preconcentration and elution of captured analytes via sheath flow assisted electrokinetic pumping are described. Coatings and monolithic polymer beds were developed for the glass devices to provide cationic surface charge and anodal electroosmotic flow for delivery to an electrospray emitter tip. A mixed cationic ([2-(methacryloyloxy)ethyl] trimethylammonium chloride) (META) and hydrophobic butyl methacrylate-based monolithic porous polymer, photopolymerized in the 6- or 8-fractionation channels, was used to capture and preconcentrate samples. A 0.45 wt% META loaded bed generated comparable anodic electroosmotic flow to the cationic polymer PolyE-323 coated channel segments in the device. The balanced electroosmotic flow allowed stable electrokinetic sheath flow to prevent cross contamination of separated protein fractions, while reducing protein/peptide adsorption on the channel walls. Sequential elution of analytes trapped in the SPE beds revealed that the monolithic columns could be efficiently used to provide sheath flow during elution of analytes, as demonstrated for neutral carboxy SNARF (residual signal, 0.08% RSD, n = 40) and charged fluorescein (residual signal, 2.5% n = 40). Elution from monolithic columns showed reproducible performance with peak area reproducibility of ~8% (n = 6 columns) in a single sequential elution and the run-to-run reproducibility was 2.4-6.7% RSD (n = 4) for elution from the same bed. The demonstrated ability of this device design and operation to elute from multiple fractionation beds into a single exit channel for sample analysis by fluorescence or electrospray mass spectrometry is a crucial component of an integrated fractionation and assay system for proteomics. PMID:23712291

Hua, Yujuan; Jemere, Abebaw B; Dragoljic, Jelena; Harrison, D Jed

2013-05-28

393

Effect of insulin and glucagon on the mobility of ESR-probes incorporated in rat liver plasma membranes.  

PubMed

1. The effect of different concentrations of insulin (INS) and glucagon (GLU) on the rotational mobility of a membrane-incorporated spin probe 2,2-6,6-tetramethyl-4-capriloyl piperidine-1-oxil (C7) was investigated by electron spin resonance (ESR) technique. 2. Two strong adenylate cyclase effectors guanosine 5'-triphosphate (GTP) and guanylyl 5'-imidodiphosphate [Gpp(NH)p], as well as an antioxidant 4-methyl-2,6-ditretbutilphenol (AO) and a nonprotein hormone prostaglandin E2 (PGE2) were used as reference effectors. 3. Applied effectors reduced by 30-82% the rotation correlation time (TR) of the rat liver plasma membranes spin probe C7. The effect was time-dependent and reached saturation 30-40 min after the effector application. 4. The kinetic- and concentration-dependent changes in TR were described by a simple phenomenological model. The apparent binding constants and the number of the apparent membrane binding sites of the effectors used were calculated using the model. PMID:8396052

Zlatanov, I; Maltzeva, E; Borovok, N; Spassov, V

1993-07-01

394

Bayesian random effect models incorporating real-time weather and traffic data to investigate mountainous freeway hazardous factors.  

PubMed

Freeway crash occurrences are highly influenced by geometric characteristics, traffic status, weather conditions and drivers' behavior. For a mountainous freeway which suffers from adverse weather conditions, it is critical to incorporate real-time weather information and traffic data in the crash frequency study. In this paper, a Bayesian inference method was employed to model one year's crash data on I-70 in the state of Colorado. Real-time weather and traffic variables, along with geometric characteristics variables were evaluated in the models. Two scenarios were considered in this study, one seasonal and one crash type based case. For the methodology part, the Poisson model and two random effect models with a Bayesian inference method were employed and compared in this study. Deviance Information Criterion (DIC) was utilized as a comparison factor. The correlated random effect models outperformed the others. The results indicate that the weather condition variables, especially precipitation, play a key role in the crash occurrence models. The conclusions imply that different active traffic management strategies should be designed based on seasons, and single-vehicle crashes have different crash mechanism compared to multi-vehicle crashes. PMID:22658460

Yu, Rongjie; Abdel-Aty, Mohamed; Ahmed, Mohamed

2012-05-31

395

Electrokinetics at aqueous interfaces without mobile charges.  

PubMed

We theoretically consider the possibility of using electric fields in aqueous channels of cylindrical and planar geometry to induce transport in the absence of mobile ionic charges. Using the Navier-Stokes equation, generalized to include the effects of water spinning, dipole orientation and relaxation, we show analytically that pumping of a dipolar liquid through an uncharged hydrophobic channel can be achieved by injecting torque into the liquid, based on the coupling between molecular spinning and fluid vorticity. This is possible using rotating electric fields and suitably chosen interfacial boundary conditions or transiently by suddenly switching on a homogeneous electric field. A static electric field, however, does not induce a steady state flow in channels, irrespective of the geometry. Using molecular dynamics (MD) simulations, we confirm that static fields do not lead to any pumping, in contrast to earlier publications. The pumping observed in MD simulations of carbon nanotubes and oil droplets in a static electric field is tracked down to an imprudent implementation of Lennard-Jones interaction truncation schemes. PMID:20099858

Bonthuis, Douwe Jan; Horinek, Dominik; Bocquet, Lydéric; Netz, Roland R

2010-08-01

396

Advances in Modeling Streambank Stability by Incorporating the Mechanical and Hydrologic Effects of Woody and Herbaceous Riparian Vegetation  

NASA Astrophysics Data System (ADS)

Sediment is one of the principle pollutants of surface waters of the United States. Sediment derived from streambanks by mass failure is a significant contributor to water-quality and land management problems. Accurately modeling streambank stability and potential mitigation strategies using riparian vegetation involves quantifying the hydrologic and mechanical factors that control the driving and resisting forces imposed by bank material, ground and surface water and the vegetation. Stabilization of streambanks using riparian vegetation offers numerous potential benefits and some potential problems that are related to mechanical and hydrological effects that are rarely quantified. In this study mechanical reinforcement of various woody and herbaceous riparian species is quantified with in situ, field measurements of root tensile strength, root sizes and root distribution that are used to calculate increases in soil cohesion. Hydrological effects of vegetation are monitored at the Goodwin Creek Experimental Watershed, Mississippi using interception plots and tensiometers under three vegetative covers: cropped grass `control' cover, clumps of eastern gamma grass, and a deciduous woody-vegetation stand. The ARS Bank-Stability Model which accounts for complex bank geometries, up to five soil layers, positive and negative pore-water pressures and confining pressure due to streamflow is used to evaluate the effectiveness of various vegetative treatments based on the field data. The model is used to evaluate the individual and combined effects of vegetation on streambank stability. On April 4 th 2000 prolonged rainfall at the field site caused bank failure at the control cover plot, providing useful validation data for the analysis. The resulting factor of safety (Fs) values (incorporating both hydrological and mechanical effects) were 1.04, 1.64 and 2.18, respectively. Results show that the main contribution of the woody-vegetation to bank stability during the study period was hydrological rather than mechanical, and that the build up of matric suction at depth during the summer months persisted throughout the winter and spring. This effect was due to transpiration rather than canopy interception losses, which were only 2% of rainfall during the study period. The beneficial hydrologic effect of woody vegetation may not be the case during wetter winters; more rapid loss of matric suction beneath woody-vegetation suggests that this bank may become less stable than the control or clump grass treatments due to enhanced infiltration of rainfall.

Simon, A.; Collison, A. J.

2001-12-01

397

Probing Into The Learning Effectiveness of Situated Learning Incorporated into a Specific Web-Assisted Instruction in Nutritional Chemistry Taken by Learners with Learning-Style Differences  

Microsoft Academic Search

In this study, the effect of situated learning theory, incorporated into a specific web-assisted instructional environment in nutritional chemistry, on learning achievements and learning satisfactions of randomly selected college students was investigated, and under such a method of instruction, its effect on learning achievements by learners with different learning styles was analyzed in depth. The study results showed: 1. The

Zang-Yuan Own; Ding-Uei Chen

398

Effect of biosolid incorporation to mollisol soils on Cr, Cu, Ni, Pb, and Zn fractionation, and relationship with their bioavailability.  

PubMed

Biosolid application to soil may be a supply of nutrients and micronutrients but it may also accumulate toxic compounds which would be absorbed by crops and through them be incorporated to the trophic chain. The present study deals with the effect of biosolid application on Cr, Cu, Pb, Ni, and Zn in agricultural soils. The procedure used is sequential extraction so that the availability of those metals may be estimated and related to their bioavailability as determined through two indicator plants grown in greenhouse: ryegrass (Lolium perenne L.) and red clover (Trifolium pratense). Results showed that biosolid application to soil increased total Cu and Zn content. Sequential extraction showed that the more labile Zn fractions increased after biosolid application to soil. This was confirmed when assessing the total content of this metal in shoot and root of the plants under study, since a higher content was found in plant tissues, while no significant differences were found for Cu, Cr, Ni, and Pb. PMID:17418882

Guerra, Paula; Ahumada, Inés; Carrasco, Adriana

2007-04-06

399

Incorporation of quantum effects for selected degrees of freedom into the trajectory-based dynamics using spatial domains.  

PubMed

The approach of defining quantum corrections on nuclear dynamics of molecular systems incorporated approximately into selected degrees of freedom, is described. The approach is based on the Madelung-de-Broglie-Bohm formulation of time-dependent quantum mechanics which represents a wavefunction in terms of an ensemble of trajectories. The trajectories follow classical laws of motion except that the quantum potential, dependent on the wavefunction amplitude and its derivatives, is added to the external, classical potential. In this framework the quantum potential, determined approximately for practical reasons, is included only into the "quantum" degrees of freedom describing light particles such as protons, while neglecting with the quantum force for the heavy, nearly classical nuclei. The entire system comprised of light and heavy particles is described by a single wavefunction of full dimensionality. The coordinate space of heavy particles is divided into spatial domains or subspaces. The quantum force acting on the light particles is determined for each domain of similar configurations of the heavy nuclei. This approach effectively introduces parametric dependence of the reduced dimensionality quantum force, on classical degrees of freedom. This strategy improves accuracy of the quantum force and does not restrict interaction between the domains. The concept is illustrated for two-dimensional scattering systems, where the quantum force is required to reproduce vibrational energy of the quantum degree of freedom. PMID:22920111

Garashchuk, Sophya; Volkov, Mikhail V

2012-08-21

400

Effect of selenophene in a DPP copolymer incorporating a vinyl group for high-performance organic field-effect transistors.  

PubMed

A new polymeric semiconductor, PDPPDTSE, is reported which is composed of a diketopyrrolopyrrole moiety and selenophenylene vinylene selenophene, with a high field-effect mobility achieved through intermolecular donor-acceptor interactions. The field-effect mobility of OFET devices based on PDPPDTSE by spin-casting is 4.97 cm(2) V(-1) s(-1) , which is higher than predecessor polymeric semiconductors. PMID:23125035

Kang, Il; An, Tae Kyu; Hong, Jung-a; Yun, Hui-Jun; Kim, Ran; Chung, Dae Sung; Park, Chan Eon; Kim, Yun-Hi; Kwon, Soon-Ki

2012-11-02

401

Evaluation of a dual-cyclodextrin phase variant of capillary electrokinetic chromatography for separations of nonionizable solutes  

Microsoft Academic Search

A capillary electrokinetic chromatography technique is described that employs neutral cyclodextrins (CDs) as a primary phase, transported with electroosmotic flow, and charged CDs as an electrophoretically mediated secondary phase. Neutral, hydrophobic solutes are separated on the basis of their differential distribution between these CD phases. The technique resembles micellar electrokinetic capillary chromatography (MECC) with regard to instrumentation and the fundamental

Michael J. Sepaniak; Christine L. Copper; Kylen W. Whitaker; Vincent C. Anigbogu

1995-01-01

402

Transient electrokinetic transport in micro/nanofluidic systems with sudden expansion and contraction cross sections  

NASA Astrophysics Data System (ADS)

This study numerically investigates electrokinetic transport in a micro/nanofluidic system by solving the transient Poisson, Nernst-Planck, and Navier-Stokes equations simultaneously. The considered system is a nanochannel connected to two micro channels at its ends. Under various applied electric potential biases, the concentration polarization effect on the fluid flow, induced pressure, and electric current is examined. By comparing with the Donnan equilibrium condition and electroosmotic flow in the microscale dimension, electric body force due to non-zero charge density is the mechanism for producing vortex flow and inducing a positive pressure gradient on the anodic side of the system. The diffusive boundary layer thickness is reduced due to stirring by the generated vortex flow, resulting in over-limiting current when the applied electric potential bias is high. The steady-state current voltage curve indicates that in the Ohmic regime, higher current can be obtained when the surface charge density is large due to higher fluid velocity. In the limiting and over-limiting current regimes, higher electric current can be obtained when the nanochannel is larger with smaller surface density because more ions are available for carrying the current. The nanochannel size effect on the limiting and over-limiting current magnitudes is insignificant when the surface charge density is large.

Chein, Reiyu; Liao, Yuchung

2013-03-01

403

Phosphonium-based ionic liquids in electrokinetic capillary chromatography for the separation of neutral analytes.  

PubMed

In this work we elucidated the applicability of phosphonium-based ionic liquids (ILs) as pseudostationary phase in electrokinetic capillary chromatography (EKC) with UV-detection. The phosphonium ILs studied contain bromide, chlorine, or tosylate ions, as counter ions, and alkyl side chains of variable length on the phosphorous atom. The effects of the type and concentration of the IL, pH, ionic strength, and type of background electrolyte solution on the electroosmotic flow (EOF) and on the effective electrophoretic mobilities of some neutral model analytes were investigated and large variations in the migration times were observed. Especially the IL employed remarkably affected the strength and direction of the EOF Successful separations were obtained for neutral aromatic singly substituted analytes, namely benzene, toluene, phenol, and nitrobenzene. The results demonstrated the potential of capillary electromigration methods for rapid interaction studies between ILs and analytes, which is useful for the development of novel materials for sample preparation and separation purposes or for novel catalyst and chemical processing studies. PMID:22796026

Wiedmer, Susanne K; King, Alistair W T; Riekkola, Marja-Liisa

2012-07-02

404

The effect of incorporation of SDF-1alpha into PLGA scaffolds on stem cell recruitment and the inflammatory response.  

PubMed

Despite significant advances in the understanding of tissue responses to biomaterials, most implants are still plagued by inflammatory responses which can lead to fibrotic encapsulation. This is of dire consequence in tissue engineering, where seeded cells and bioactive components are separated from the native tissue, limiting the regenerative potential of the design. Additionally, these interactions prevent desired tissue integration and angiogenesis, preventing functionality of the design. Recent evidence supports that mesenchymal stem cells (MSC) and hematopoietic stem cells (HSC) can have beneficial effects which alter the inflammatory responses and improve healing. The purpose of this study was to examine whether stem cells could be targeted to the site of biomaterial implantation and whether increasing local stem cell responses could improve the tissue response to PLGA scaffold implants. Through incorporation of SDF-1alpha through factor adsorption and mini-osmotic pump delivery, the host-derived stem cell response can be improved resulting in 3X increase in stem cell populations at the interface for up to 2 weeks. These interactions were found to significantly alter the acute mast cell responses, reducing the number of mast cells and degranulated mast cells near the scaffold implants. This led to subsequent downstream reduction in the inflammatory cell responses, and through altered mast cell activation and stem cell participation, increased angiogenesis and decreased fibrotic responses to the scaffold implants. These results support that enhanced recruitment of autologous stem cells can improve the tissue responses to biomaterial implants through modifying/bypassing inflammatory cell responses and jumpstarting stem cell participation in healing at the implant interface. PMID:20185171

Thevenot, Paul T; Nair, Ashwin M; Shen, Jinhui; Lotfi, Parisa; Ko, Cheng-Yu; Tang, Liping

2010-02-24

405

An experimental test of new theoretical models for the electrokinetic properties of biological membranes. The effect of UO2++ and tetracaine on the electrophoretic mobility of bilayer membranes and human erythrocytes  

PubMed Central

For a large smooth particle with charges at the surface, the electrophoretic mobility is proportional to the zeta potential, which is related to the charge density by the Gouy-Chapman theory of the diffuse double layer. This classical model adequately describes the dependence of the electrophoretic mobility of phospholipid vesicles on charge density and salt concentration, but it is not applicable to most biological cells, for which new theoretical models have been developed. We tested these new models experimentally by measuring the effect of UO2++ on the electrophoretic mobility of model membranes and human erythrocytes in 0.15 M NaCl at pH 5. We used UO2++ for these studies because it should adsorb specifically to the bilayer surface of the erythrocyte and should not change the density of fixed charges in the glycocalyx. Our experiments demonstrate that it forms high-affinity complexes with the phosphate groups of several phospholipids in a bilayer but does not bind significantly to sialic acid residues. As observed previously, UO2++ adsorbs strongly to egg phosphatidylcholine (PC) vesicles: 0.1 mM UO2++ changes the zeta potential of PC vesicles from 0 to +40 mV. It also has a large effect on the electrophoretic mobility of vesicles formed from mixtures of PC and the negative phospholipid phosphatidylserine (PS): 0.1 mM UO2++ changes the zeta potential of PC/PS vesicles (10 mol % PS) from -13 to +37 mV. In contrast, UO2++ has only a small effect on the electrophoretic mobility of either vesicles formed from mixtures of PC and the negative ganglioside GM1 or erythrocytes: 0.1 mM UO2++ changes the apparent zeta potential of PC/GM1 vesicles (17 mol % GM1) from -11 to +5 mV and the apparent zeta potential of erythrocytes from -12 to -4 mV. The new theoretical models suggest why UO2++ has a small effect on PC/GM1 vesicles and erythrocytes. First, large groups (e.g., sugar moieties) protruding from the surface of the PC/GM1 vesicles and erythrocytes exert hydrodynamic drag. Second, charges at the surface of a particle (e.g., adsorbed UO2++) exert a smaller effect on the mobility than charges located some distance from the surface (e.g., sialic acid residues).

1986-01-01

406

The effects of functional magnetic nanotubes with incorporated nerve growth factor in neuronal differentiation of PC12 cells.  

PubMed

In this in vitro study the efficiency of magnetic nanotubes to bind with nerve growth factor (NGF) and the ability of NGF-incorporated magnetic nanotubes to release the bound NGF are investigated using rat pheochromocytoma cells (PC12 cells). It is found that functional magnetic nanotubes with NGF incorporation enabled the differentiation of PC12 cells into neurons exhibiting growth cones and neurite outgrowth. Microscope observations show that filopodia extending from neuron growth cones were in close proximity to the NGF-incorporated magnetic nanotubes, at times appearing to extend towards or into them. These results show that magnetic nanotubes can be used as a delivery vehicle for NGF and thus may be exploited in attempts to treat neurodegenerative disorders such as Parkinson's disease with neurotrophins. Further neurite outgrowth can be controlled by manipulating magnetic nanotubes with external magnetic fields, thus helping in directed regeneration. PMID:21817692

Xie, Jining; Chen, Linfeng; Varadan, Vijay K; Yancey, Justin; Srivatsan, Malathi

2008-02-13

407

The effects of functional magnetic nanotubes with incorporated nerve growth factor in neuronal differentiation of PC12 cells  

NASA Astrophysics Data System (ADS)

In this in vitro study the efficiency of magnetic nanotubes to bind with nerve growth factor (NGF) and the ability of NGF-incorporated magnetic nanotubes to release the bound NGF are investigated using rat pheochromocytoma cells (PC12 cells). It is found that functional magnetic nanotubes with NGF incorporation enabled the differentiation of PC12 cells into neurons exhibiting growth cones and neurite outgrowth. Microscope observations show that filopodia extending from neuron growth cones were in close proximity to the NGF-incorporated magnetic nanotubes, at times appearing to extend towards or into them. These results show that magnetic nanotubes can be used as a delivery vehicle for NGF and thus may be exploited in attempts to treat neurodegenerative disorders such as Parkinson's disease with neurotrophins. Further neurite outgrowth can be controlled by manipulating magnetic nanotubes with external magnetic fields, thus helping in directed regeneration.

Xie, Jining; Chen, Linfeng; Varadan, Vijay K.; Yancey, Justin; Srivatsan, Malathi

2008-03-01

408

42 CFR 137.48 - What is the effect of incorporating a Title I provision into a compact or funding agreement?  

Code of Federal Regulations, 2011 CFR

...incorporating a Title I provision into a compact or funding agreement? 137.48 Section 137.48 Public...AND HUMAN SERVICES TRIBAL SELF-GOVERNANCE Funding Agreements Terms in A Funding Agreement § 137.48 What is the effect...

2011-10-01

409

42 CFR 137.48 - What is the effect of incorporating a Title I provision into a compact or funding agreement?  

Code of Federal Regulations, 2012 CFR

...incorporating a Title I provision into a compact or funding agreement? 137.48 Section 137.48 Public...AND HUMAN SERVICES TRIBAL SELF-GOVERNANCE Funding Agreements Terms in A Funding Agreement § 137.48 What is the effect...

2012-10-01

410

Scale-up effects on kinetic parameters and on predictions of a yeast recycle continuous ethanol fermentation model incorporating loss of cell viability  

Microsoft Academic Search

The scale-up effects on kinetic parameters and on predictions of a yeast recycle continuous ethanol fermentation model incorporating loss of cell viability were evaluated. The average level of cell viability estimated for large scale was similar to that estimated for small scale, although with a major standard deviation. The values of specific rate of cell viability loss were equal for

S. C. Oliveira; H. F. De Castro; A. E. S. Visconti; R. Giudici

2000-01-01

411

Incorporating Small Fatigue Crack Growth in Probabilistic Life Prediction: Effect of Stress Ratio in Ti-6Al-2Sn-4Zr-6-Mo (Preprint).  

National Technical Information Service (NTIS)

The effect of stress ratio on the statistical aspects of small fatigue crack growth behavior was studied in a duplex microstructure of Ti-6Al- 2Sn-4Zr-6Mo (Ti-6-2-4-6) at 260 degrees C with particular emphasis on incorporating small-crack data into probab...

J. M. Larsen R. John S. K. Jha

2012-01-01

412

Phosphorus incorporation during Si(001):P gas-source molecular beam epitaxy: Effects on growth kinetics and surface morphology  

SciTech Connect

The effects of P doping on growth kinetics and surface morphological evolution during Si(001):P gas-source molecular beam epitaxy from Si{sub 2}H{sub 6} and PH{sub 3} at temperatures T{sub s}=500-900 deg. C have been investigated. With increasing PH{sub 3}/Si{sub 2}H{sub 6} flux ratio J{sub P/Si} at constant T{sub s}, we observe a decrease in the film growth rate R and an increase in the incorporated P concentration C{sub P}, both of which tend toward saturation at high flux ratios, which is accompanied by increased surface roughening and pit formation. At constant J{sub P/Si}, R increases with increasing T{sub s}, while C{sub P} initially increases, reaches a maximum at T{sub s}=700 deg. C, and then decreases at higher growth temperatures. We use in situ isotopically tagged D{sub 2} temperature programed desorption (TPD) to follow changes in film surface composition and dangling bond density {theta}{sub db} as a function of J{sub P/Si} and T{sub s}. Measurements are carried out on both as-deposited Si(001):P layers and P-adsorbed Si(001) surfaces revealing {beta}{sub 1} and {beta}{sub 2} peaks due to D{sub 2} desorption from Si monohydride and dihydride species, respectively, as well as the formation of a third peak {beta}{sub 3} corresponding to D{sub 2} desorption from mixed Si-P dimers. Dissociative PH{sub 3} adsorption on Si(001) results in a decrease in {theta}{sub db} and an initial increase in P surface coverage {theta}{sub P} with increasing T{sub s}. Saturation {theta}{sub P} values reach a maximum of {approx}1 ML at T{sub s}=550 deg. C, and decrease with T{sub s}>600 deg. C due to the onset of P{sub 2} desorption. Comparison of {theta}{sub P}(T{sub s}) results obtained during film growth with postdeposition C{sub P}(T{sub s}) results reveals the presence of strong P surface segregation. From measurements of {theta}{sub P} versus C{sub P} in Si(001):P layers grown as a function of T{sub s}, we obtain a P segregation enthalpy {delta}H{sub s}=-0.86 eV. By using the combined set of results, we develop a predictive model for C{sub P} versus T{sub s} and, J{sub P/Si} incorporating the dependence of the PH{sub 3} reactive sticking probability S{sub PH{sub 3}} on {theta}{sub P}, which provides an excellent fit to the experimental data.

Cho, B.; Bareno, J.; Foo, Y. L.; Hong, S.; Spila, T.; Petrov, I.; Greene, J. E. [Materials Science Department and the Frederick-Seitz Materials Research Laboratory, University of Illinois, 104 South Goodwin Ave., Urbana, Illinois 61801 (United States)

2008-06-15

413

Dose and time dependent effects of morphine on the incorporation of (3H)valine into soluble brain and liver proteins  

SciTech Connect

Morphine (10(-6)-10(-5) M) causes an increase in incorporation of (/sup 3/H)valine into soluble proteins during 4 hr in rat brain cortical slices, liver slices and cultivated astroglial cells. The effects are dose-dependent. They are neither cell specific nor strictly related to classical opiate receptors. Pulse-labeling with (/sup 3/H)valine for 60 min after incubation in 10(-6)-10(-5) M morphine, resolves time-dependent changes in incorporation, with both increases and decreases in protein metabolism.

Roennbaeck, L.; Hansson, E.; Cupello, A.

1983-03-01

414

Effect of hypoxia on the incorporation of (2-3H) glycerol and (1-14C(-palmitate into lipids of various brain regions  

SciTech Connect

The lipid metabolism in guinea pig brain after intermittent hypoxia, prolonged for 80 hrs, was markedly impaired. The in vivo incorporation of (2-3H) glycerol and (1-14C) palmitate into lipids of microsomes, mitochondria, myelin, and synaptosomes, purified form cerebral hemispheres, was significantly lower in the hypoxic animals than in the controls. The same effect was observed on the incorporation of labeled precursors into lipids of mitochondria purified from cerebellum and brainstem. In particular, the labeling of th major phospholipids present - ie, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) - in the mitochondria of the three brain regions examined decreased after hypoxic treatment.

Alberghina, M.; Giuffrida, A.M.

1981-01-01

415

Enhanced electrokinetic treatment of different marine sediments contaminated by heavy metals.  

PubMed

In the present work, the application of an assisted electrokinetic process for the removal of heavy metals from real contaminated sediments was investigated. The process made use of both chemical and physical methods, including addition of chelating and acid agents, as well as application of a hydraulic gradient. Lab-scale electrokinetic runs were applied on two different dredged sediments varying the applied voltage gradient and the treatment duration. The use of EDTA significantly improved the overall performance of the electrokinetic treatment for sediment V (more than 60% mobilized for each metal), while only aggressive acid conditioning with nitric acid was able to remove significant amounts of heavy metals (up to 40.5% for Pb) from sediment S due to the strong buffering capacity of this material. This clearly assesses that the specific characteristics of the materials under concern and the reactions occurring at the electrodes must be carefully evaluated when applying an electroremediation process. PMID:18569295

De Gioannis, Giorgia; Muntoni, Aldo; Polettini, Alessandra; Pomi, Raffaella

2008-07-01

416

Simultaneous determination of flavonoids in Ixeridium gracile by micellar electrokinetic chromatography.  

PubMed

A micellar electrokinetic chromatography (MEKC) method has been developed for the quantitative analysis of five flavonoids: luteolin 7-O-glucoside (LG), 2',4'-dihydroxy-dihydrochalcone (DD), 2',4'-dihydroxy-chalcone (DC), 7-hydroxy-flavanone (HF) and quercetin 3-O-galactoside (QG) in Ixeridium gracile with UV detection at 275 nm. The applied voltage was 25 kV and the capillary temperature was kept constant at 25 degrees C. The effects of buffer pH, the concentration of electrolyte and organic modifier on migration behavior were studied. Optimum separation condition was achieved with 15 mM borate, 30 mM sodium dodecyl sulfate (SDS) and 10% (v/v) ethanol at pH 10.5. Regression equations showed good linear relationships (correlation coefficients: 0.9984, 0.9991, 0.9994, 0.9995 and 0.9997) between the peak area of each compound and their concentrations. The relative standard deviations (R.S.D.) of the migration time and peak area were less 1.67 and 3.53% (intra-day), and 1.82 and 3.73% (inter-day), respectively, under the optimum separation conditions. The contents of the five active compounds in I. gracile were determined with satisfactory repeatability and recovery. PMID:17889478

Zhang, Yu; Chen, Juan; Ma, Xue-Mei; Shi, Yan-Ping

2007-08-19

417

Chiral micellar electrokinetic chromatography (CMEKC)-atmospheric pressure photoionization of benzoin derivatives using mixed molecular micelles  

PubMed Central

In the present work we report, for the first time, the successful on-line coupling of chiral micellar electrokinetic chromatography (CMEKC) to atmospheric pressure photo-ionization mass spectrometry (APPI-MS). Four structurally similar neutral test solutes (e.g., benzoin derivatives) were successfully ionized by APPI-MS. The mass spectra in the positive ion mode showed that the protonated molecular ions of benzoins are not the most abundant fragment ions. Simultaneous enantioseparation by CMEKC and on-line APPI-MS detection of four photoinitiators: hydrobenzoin (HBNZ), benzoin (BNZ), benzoin methyl ether (BME), benzoin ethyl ether (BEE), were achieved using an optimized molar ratio of mixed molecular micelle of two polymeric chiral surfactants (polysodium N-undecenoxy carbonyl-L-leucinate and polysodium N-undecenoyl-L,L-leucylvalinate). The CMEKC conditions, such as voltage, chiral polymeric surfactant concentration, buffer pH, and BGE concentration, were optimized using a multivariate central composite design (CCD). The sheath liquid composition (involving % v/v methanol, dopant concentration, electrolyte additive concentration, and flow rate) and spray chamber parameters (drying gas flow rate, drying gas temperature, and vaporizer temperature) were also optimized with CCD. Models built based on the CCD results and response surface method was used to analyze the interactions between factors and their effects on the responses. The final overall optimum conditions for CMEKC-APPI-MS were also predicted and found in agreement with the experimentally optimized parameters.

He, Jun; Shamsi, Shahab A.

2012-01-01

418

Separation and analysis of the major constituents of cloves by micellar electrokinetic chromatography.  

PubMed

A micellar electrokinetic chromatographic method was developed and applied for the first time to the separation and quantification of the main components of cloves, namely eugenol and beta-caryophyllene. The analytes were separated in less than ten minutes in an unmodified fused silica capillary (effective length: 40.0 cm) using a background electrolyte composed of 25 mM carbonate buffer (pH 10.0) and 60 mM sodium dodecylsulfate. Analyte concentrations were determined in clove oil and in methanolic clove extracts after simple sequential dilution with methanol and background electrolyte, and the resulting electropherograms showed no interference due to other components. Precision assays gave satisfactory results, with mean standard deviation of peak areas lower than 4.7% (lower than 1.5% for migration times). The eugenol content of a commercial clove oil was about 70% (RSD% = 3.2), while that of beta-caryophyllene was about 15% (RSD% = 4.2); in clove extracts, on the other hand, eugenol was approximately 15% (RSD% = 4.7) and beta-caryophyllene 4% (RSD% = 5.1). Accuracy was also good (mean recovery >98%). PMID:16013823

Mandrioli, Roberto; Musenga, Alessandro; Ferranti, Anna; Lasaponara, Stefano Savino; Fanali, Salvatore; Raggi, Maria Augusta

2005-06-01

419

Direct photodegradation of carbamazepine followed by micellar electrokinetic chromatography and mass spectrometry.  

PubMed

Carbamazepine, a widely consumed psychotropic pharmaceutical, is one of the most commonly detected drugs in the environment. To better assess the environmental persistence of carbamazepine in aqueous matrices, the effect of pH and dissolved oxygen on the direct photodegradation rate of this pharmaceutical was evaluated in this study, using simulated solar irradiation. In order to follow the degradation and the emergence of photoproducts, a micellar electrokinetic chromatography based method was developed, consisting on the use of a dynamically coated capillary column. The developed methodology showed good repeatability and efficiency in the separation of carbamazepine and photoirradiation products. Also, seven photodegradation products were identified by electrospray mass spectrometry (ESI-MS), including the known carcinogenic acridine that was produced under all the pH and oxygenation levels studied and one newly identified photoproduct. This paper gives new insights into the role of dissolved oxygen on the photodegradation rate of carbamazepine. The results indicate that acidic pH, combined with the absence of dissolved oxygen in the aqueous matrix, results in very high direct photodegradation rates. At basic pH, dissolved oxygen does not interfere with the process and very low rates were observed. At environmentally relevant conditions, carbamazepine was shown to persist in the environment from 4.5 to 25 days. PMID:21106217

Calisto, Vânia; Domingues, M Rosário M; Erny, Guillaume L; Esteves, Valdemar I

2010-11-05

420

Mixing of non-Newtonian fluids in wavy serpentine microchannel using electrokinetically driven flow.  

PubMed

A numerical investigation is performed into the mixing performance of electrokinetically driven non-Newtonian fluids in a wavy serpentine microchannel. The flow behavior of the non-Newtonian fluids is described using a power-law model. The simulations examine the effects of the flow behavior index, the wave amplitude, the wavy-wall section length, and the applied electric field strength on the mixing performance. The results show that the volumetric flow rate of shear-thinning fluids is higher than that of shear-thickening fluids, and therefore results in a poorer mixing performance. It is shown that for both types of fluid, the mixing performance can be enhanced by increasing the wave amplitude, extending the length of the wavy-wall section, and reducing the strength of the electric field. Thus, although the mixing efficiency of shear-thinning fluids is lower than that of shear-thickening fluids, the mixing performance can be improved through an appropriate specification of the flow and geometry parameters. For example, given a shear-thinning fluid with a flow behavior index of 0.8, a mixing efficiency of 87% can be obtained by specifying the wave amplitude as 0.7, the wavy-wall section length as five times the characteristic length, the nondimensional Debye-Huckel parameter as 100, and the applied electric field strength as 43.5 V/cm. PMID:22522530

Cho, Ching-Chang; Chen, Chieh-Li; Chen, Cha'o-Kuang

2012-03-01

421

Dispersion stability and electrokinetic properties of intrinsic plutonium colloids: implications for subsurface transport.  

PubMed

Subsurface transport of plutonium (Pu) may be facilitated by the formation of intrinsic Pu colloids. While this colloid-facilitated transport is largely governed by the electrokinetic properties and dispersion stability (resistance to aggregation) of the colloids, reported experimental data is scarce. Here, we quantify the dependence of ?-potential of intrinsic Pu(IV) colloids on pH and their aggregation rate on ionic strength. Results indicate an isoelectric point of pH 8.6 and a critical coagulation concentration of 0.1 M of 1:1 electrolyte at pH 11.4. The ?-potential/pH dependence of the Pu(IV) colloids is similar to that of goethite and hematite colloids. Colloid interaction energy calculations using these values reveal an effective Hamaker constant of the intrinsic Pu(IV) colloids in water of 1.85 × 10(-19) J, corresponding to a relative permittivity of 6.21 and refractive index of 2.33, in agreement with first principles calculations. This relatively high Hamaker constant combined with the positive charge of Pu(IV) colloids under typical groundwater aquifer conditions led to two contradicting hypotheses: (a) the Pu(IV) colloids will exhibit significant aggregation and deposition, leading to a negligible subsurface transport or (b) the Pu(IV) colloids will associate with the relatively stable native groundwater colloids, leading to a considerable subsurface transport. Packed column transport experiments supported the second hypothesis. PMID:23675849

Abdel-Fattah, Amr I; Zhou, Dongxu; Boukhalfa, Hakim; Tarimala, Sowmitri; Ware, S Doug; Keller, Arturo A

2013-05-15

422

A Novel Micellar Electrokinetic Chromatographic Method for Separation of Metal-DDTC Complexes  

PubMed Central

Micellar electrokinetic chromatography (MEKC) was examined for the separation and determination of Mo(VI), Cr(VI), Ni(II), Pd(II), and Co(III) as diethyl dithiocarbamate (DDTC) chelates. The separation was achieved from fused silica capillary (52?cm?×?75??m?id) with effective length 40?cm, background electrolyte (BGE) borate buffer pH?9.1 (25?mM), CTAB 30% (100?mM), and 1% butanol in methanol (70?:?30?:?5?v/v/v) with applied voltage of ?10?kV using reverse polarity. The photodiode array detection was achieved at 225?nm. The linear calibration for each of the element was obtained within 0.16–10??g/mL with a limit of detection (LOD) 0.005–0.0167??g/mL. The separation and determination was repeatable with relative standard deviation (RSD) within 2.4–3.3% (n = 4) in terms of migration time and peak height/peak area. The method was applied for the determination of Mo(VI) from potatoes and almond, Ni(II) from hydrogenated vegetable oil, and Co(III) from pharmaceutical preparations with RSD within 3.9%. The results obtained were checked by standard addition and rechecked by atomic absorption spectrometry.

Mallah, Arfana; Memon, Saima Q.; Solangi, Amber R.; Memon, Najma; Abbassi, Kulsoom; Khuhawar, Muhammad Yar

2012-01-01

423

A novel microfluidic mixer utilizing electrokinetic driving forces under low switching frequency.  

PubMed

This paper presents a novel technique in which low-frequency periodic electrokinetic driving forces are utilized to mix electrolytic fluid samples rapidly and efficiently in a double-T-form microfluidic mixer. Without using any additional equipment to induce flow perturbations, only a single high-voltage power source is required for simultaneously driving and mixing the sample fluids which results in a simple and low-cost system for the mixing purpose. The effectiveness of the mixer as a function of the applied electric field and the periodic switching frequency is characterized by the intensity distribution calculated downstream from the mixing zone. The present numerical and experimental results confirm that the proposed double-T-form micromixer has excellent mixing capabilities. The mixing efficiency can be as high as 95% within a mixing length of 1000 microm downstream from the secondary T-junction when a 100 V/cm driving electric field strength and a 2 Hz periodic switching frequency are applied. The results reveal that the optimal switching frequency depends upon the magnitude of the main applied electrical field. The rapid double-T-form microfluidic mixer using the periodic driving voltage switching model proposed in this study has considerable potential for use in lab-on-a-chip systems. PMID:15754383

Fu, Lung-Ming; Yang, Ruey-Jen; Lin, Che-Hsin; Chien, Yu-Sheng

2005-05-01

424

Simultaneous determination of lovastatin and citrinin in red yeast rice supplements by micellar electrokinetic capillary chromatography.  

PubMed

Lovastatin is a main component of Monascus purpureus fermented red rice contributing to the lipid-lowering effect. Citrinin is a toxic fermentation by-product which can be found as a contaminant. An accurate, simple and rapid micellar electrokinetic capillary chromatographic method was developed for the first time for simultaneous determination of lovastatin present in lactone and hydroxy acid forms and citrinin in red rice products provided by different manufacturers and formulated in various dosage forms. Separation was achieved within only 2 min using 20 mM of phosphate buffer at pH 7.0 and 30 mM of sodium dodecyl sulphate at an applied voltage of 25 kV. Sensitivity crucial for detecting citrinin was enhanced by using an extended light path capillary. The results showed that the content of lovastatin and its acid form in dietary supplements were considerably different indicating the need for improved standardization in order to ensure efficiency and safety of these products. PMID:23265521

Nigovi?, Biljana; Serti?, Miranda; Mornar, Ana

2012-11-12

425

On-line monitoring system for chemical warfare agents using automated capillary micellar electrokinetic chromatography.  

PubMed

We present an automated analysis system for the detection of the chemical warfare blister agents, sulfur mustard (HD) and lewisite (L), in aqueous samples without any chemical derivatization. The system is compact in size and designed to operate in the field in a safe, autonomous manner for near real-time monitoring applications. It uses anionic surfactant-based capillary micellar electrokinetic chromatography (MEKC) to separate the sample followed by UV detection. The analysis time is sufficiently fast to allow direct detection of HD which enabled the estimation of effective hydrolysis rates in the aqueous sample matrix. The estimated hydrolysis half-life of HD in our system was 4.85 ± 0.05 min. The detection limit of HD was determined to be 10 ppm with a signal to noise ratio of 5. By contrast, L hydrolyzed too rapidly in aqueous samples to enable direct detection. Instead the first hydrolysis product 2-chlorovinyl arsonous acid (CVAA), also considered a blister agent, was detected with a detection limit of 0.7 ppm with a signal to noise ratio of 5. PMID:22749453

Vandernoot, Victoria; Ferko, Scott; Van De Vreugde, James; Patel, Kamlesh; Volponi, Joanne; Morrissey, Kevin; Forrest, Lucille