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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

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

3

Effects of electrostatic correlations on electrokinetic phenomena.  

PubMed

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. PMID:23214872

Storey, Brian D; Bazant, Martin Z

2012-11-01

4

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

5

Modeling forced liquid convection in rectangular microchannels with electrokinetic effects  

Microsoft Academic Search

The effects of the electric double layer near the solid–liquid interface and the flow induced electrokinetic field on the pressure-driven flow and heat transfer through a rectangular microchannel are analyzed in this work. The electric double layer field in the cross-section of rectangular microchannels is determined by solving a non-linear, two-dimensional Poisson–Boltzmann equation. A body force caused by the electric

Chun Yang; Dongqing Li; Jacob H. Masliyah

1998-01-01

6

Nonequilibrium electrokinetic effects in beds of ion-permselective particles.  

PubMed

Electrokinetic transport of fluorescent tracer molecules in a bed of porous glass beads was investigated by confocal laser scanning microscopy. Refractive index matching between beads and the saturating fluid enabled a quantitative analysis of intraparticle and extraparticle fluid-side concentration profiles. Kinetic data were acquired for the uptake and release of electroneutral and counterionic tracer under devised conditions with respect to constant pressure-driven flow through the device and the effect of superimposed electrical fields. Transport of neutral tracer is controlled by intraparticle mass transfer resistance which can be strongly reduced by electroosmotic flow, while steady-state distributions and bead-averaged concentrations are unaffected by the externally applied fields. Electrolytes of low ionic strength caused the transport through the charged (mesoporous) beads to become highly ion-permselective, and concentration polarization is induced in the bulk solution due to the superimposed fields. The depleted concentration polarization zone comprises extraparticle fluid-side mass transfer resistance. Ionic concentrations in this diffusion boundary layer decrease at increasing field strength, and the flux densities approach an upper limit. Meanwhile, intraparticle transport of counterions by electromigration and electroosmosis continues to increase and finally exceeds the transport from bulk solution into the beads. A nonequilibrium electrical double layer is induced which consists of mobile and immobile space charge regions in the extraparticle bulk solution and inside a bead, respectively. These electrical field-induced space charges form the basis for nonequilibrium electrokinetic phenomena. Caused by the underlying transport discrimination (intraparticle electrokinetic vs extraparticle boundary-layer mass transfer), the dynamic adsorption capacity for counterions can be drastically reduced. Further, the extraparticle mobile space charge region leads to nonlinear electroosmosis. Flow patterns can become highly chaotic, and electrokinetic instability mixing is shown to increase lateral dispersion. Under these conditions, the overall axial dispersion of counterionic tracer can be reduced by more than 2 orders of magnitude, as demonstrated by pulse injections. PMID:15595793

Leinweber, Felix C; Tallarek, Ulrich

2004-12-21

7

Ion-specific anomalous electrokinetic effects in hydrophobic nanochannels.  

PubMed

We show with computer simulations that anomalous electrokinetic effects, such as ion specificity and nonzero zeta potentials for uncharged surfaces, are generic features of electro-osmotic flow in hydrophobic channels. This behavior is due to the stronger attraction of larger ions to the "vapor-liquidlike" interface induced by a hydrophobic surface. We propose an analytical model involving a modified Poisson-Boltzmann description for the ion density distributions that quantitatively predicts the anomalous flow profiles. This description includes as a crucial component an ion-size-dependent hydrophobic solvation energy. These results provide an effective framework for predicting ion-specific effects, with potentially important implications for biological modeling. PMID:17501535

Huang, David M; Cottin-Bizonne, Cécile; Ybert, Christophe; Bocquet, Lydéric

2007-04-27

8

Electrokinetic effects on motion of submicron particles in microchannel  

NASA Astrophysics Data System (ADS)

Two-fluid mixing utilizing electrokinetically driven flow in a micro-channel is investigated by micron-resolution particle image velocimetry and an image processing technique. Submicron particles are transported and mixed with deionized water by electrophoresis. The particle electrophoretic velocity that is proportional to an applied electric field is measured in a closed cell, which is used to calculate the electroosmotic flow velocity. At a constant electric field, addition of pressure-driven flow to electrokinetically driven flow in a T-shaped micro-channel enhances two-fluid mixing because the momentum flux is increased. On the other hand, on application of an alternative sinusoidal electric field, the velocity difference between pressure-driven and electroosmotic flows has a significant effect on increasing the length of interface formed between two fluids. It is concluded from the present experiments that the transport and mixing process in the micro-channel will be enhanced by accurate flow-rate control of both pressure-driven and electroosmotic flows.

Sato, Yohei; Hishida, Koichi

2006-11-01

9

Electrokinetic instability effects in microchannels with and without nanofilm coatings.  

PubMed

This paper presents a parametric experimental investigation into the electrokinetic instability (EKI) phenomenon within three different types of microfluidic device, namely T-type, cross-shaped, and cross-form with an expansion configuration. The critical electric field strength at which the EKI phenomenon is induced is examined as a function of the conductivity ratio, the microchannel width, the expansion ratio, and the surface treatment of the microchannel walls. It is found that the critical electric field strength associated with the onset of EKI is strongly dependent on the conductivity ratio of the two samples within the microfluidic device and reduces as the channel width increases. The surfaces of the microchannel walls are coated with hydrophilic or hydrophobic organic-based spin-on-glass (SOG) nanofilms for glass-based microchips. The experimental results indicate that no significant difference exists in the critical electric field strengths in the hydrophilic or hydrophobic SOG-coated microchannels, respectively. However, for a given conductivity ratio and microchannel width, the critical strength of the electric field is slightly lower in the SOG-coated microchannels than in the non-coated channels. In general, the results presented in this study demonstrate the potential for designing and controlling on-chip assays requiring the manipulation of samples with high conductivity gradients, and provide a useful general reference for avoiding EKI effects in capillary electrophoresis analysis applications. PMID:19130549

Fu, Lung-Ming; Hong, Ting-Fu; Wen, Chih-Yung; Tsai, Chien-Hsiung; Lin, Che-Hsin

2008-12-01

10

Sub-Grid Modeling of Electrokinetic Effects in Micro Flows  

NASA Technical Reports Server (NTRS)

Advances in micro-fabrication processes have generated tremendous interests in miniaturizing chemical and biomedical analyses into integrated microsystems (Lab-on-Chip devices). To successfully design and operate the micro fluidics system, it is essential to understand the fundamental fluid flow phenomena when channel sizes are shrink to micron or even nano dimensions. One important phenomenon is the electro kinetic effect in micro/nano channels due to the existence of the electrical double layer (EDL) near a solid-liquid interface. Not only EDL is responsible for electro-osmosis pumping when an electric field parallel to the surface is imposed, EDL also causes extra flow resistance (the electro-viscous effect) and flow anomaly (such as early transition from laminar to turbulent flow) observed in pressure-driven microchannel flows. Modeling and simulation of electro-kinetic effects on micro flows poses significant numerical challenge due to the fact that the sizes of the double layer (10 nm up to microns) are very thin compared to channel width (can be up to 100 s of m). Since the typical thickness of the double layer is extremely small compared to the channel width, it would be computationally very costly to capture the velocity profile inside the double layer by placing sufficient number of grid cells in the layer to resolve the velocity changes, especially in complex, 3-d geometries. Existing approaches using "slip" wall velocity and augmented double layer are difficult to use when the flow geometry is complicated, e.g. flow in a T-junction, X-junction, etc. In order to overcome the difficulties arising from those two approaches, we have developed a sub-grid integration method to properly account for the physics of the double layer. The integration approach can be used on simple or complicated flow geometries. Resolution of the double layer is not needed in this approach, and the effects of the double layer can be accounted for at the same time. With this approach, the numeric grid size can be much larger than the thickness of double layer. Presented in this report are a description of the approach, methodology for implementation and several validation simulations for micro flows.

Chen, C. P.

2005-01-01

11

Thermally biased AC electrokinetic pumping effect for lab-on-a-chip based delivery of biofluids.  

PubMed

One major motivation for microfluidic research is to develop point of care diagnostic tools, which often demands a solution for chip-scale pumping that is of low cost, small size and light weight. Electrokinetics has been extensively studied for disposable pumping since only electrodes are needed to induce microflows. However, it encounters difficulties with conductive biofluids because of the associated high salt content. In electrokinetic pumps, electrodes are in direct contact with fluid, so high salt content will compress the electric double layer that is essential to electroosmostic flows. Alternating current electrothermal (ACET) effect is the only electrokinetic method found viable for biofluid actuation. While high frequency (>10 kHz) operation can suppress electrochemical reactions, electrical potential that could be applied over biofluids is still limited within several volts due to risk of electrolysis or impedance mismatch. Since ACET flow velocity has a quartic dependence on the voltage, ACET flows would be rather slow if electric field alone is used for actuation. This work studies the effect of a thermal bias on enhancing AC electrokinetic pumping. With proper imposition of external thermal gradients, significant improvement in flow velocity has been demonstrated by numerical simulation and preliminary experiments. Both showed that with 4 V(rms) at 100 kHz, flow velocity increased from ~10 ?m/s when there was no thermal biasing to ~112 ?m/s when a heat flux was applied. PMID:22932955

Yuan, Quan; Wu, Jie

2013-02-01

12

Chemoelectronic mobilization of chemical species in low-conductivity fluids: new electrokinetic effect.  

PubMed Central

An electrokinetic phenomenon is reported here which differs from its classical counterparts most distinctively by nonlinear conductivity and mobility. Neither purely electrolytic nor electrostatic in nature, this phenomenon is presumed to involve subtle charge transfer effects and association reactions permitting a controlled "chemoelectric" mobilization. In its electrokinetic manifestation, this phenomenon can be used to mobilize chemical species commonly with migration rates orders of magnitude greater than can be achieved electrophoretically and is shown to induce the movement of nonpolar molecules, such as aromatic hydrocarbons, at rates exceeding several centimeters per minute in easily achievable voltage gradients. The operational technique, developed as a separations method used for demonstrating the effect, is called "electromolecular propulsion". Images

Haber, N

1982-01-01

13

Effect of ionic concentration on electrokinetic instability in a cross-shaped microchannel  

Microsoft Academic Search

This paper performs numerical and experimental investigations into electrokinetic instability (EKI) effects to accomplish\\u000a mixing of multiple solutions with different electric conductivities in a cross-shaped microchannel. This study considers two\\u000a multiple-species, namely two aqueous electrolyte solutions and three electrolyte solutions with conductivity ratios ranging\\u000a between 1 and 10, respectively. A stratified flow condition is formed when the intensity of the

Win-Jet Luo

2009-01-01

14

Fundamentals of electrokinetics  

SciTech Connect

The study of electrokinetics is a very mature field. Experimental studies date from the early 1800s, and acceptable theoretical analyses have existed since the early 1900s. The use of electrokinetics in practical field problems is more recent, but is still quite mature. Most developments in the fundamental understanding of electrokinetics have been in the colloid science literature. A significant and increasing divergence between the theoretical understanding of electrokinetics found in the colloid science literature and the theoretical analyses used in interpreting applied experimental studies in soil science and waste remediation has developed. The soil science literature has to data restricted itself to the use of very early theories, with their associated limitations. The purpose of this contribution is to review fundamental aspects of electrokinetic phenomena from a colloid science viewpoint. It is hoped that a bridge can be built between the two branches of the literature, from which both will benefit. Attention is paid to special topics such as the effects of overlapping double layers, applications in unsaturated soils, the influence of dispersivity, and the differences between electrokinetic theory and conductivity theory.

Kozak, M.W.

1991-01-01

15

Fundamentals of electrokinetics  

SciTech Connect

The study of electrokinetics is a very mature field. Experimental studies date from the early 1800s, and acceptable theoretical analyses have existed since the early 1900s. The use of electrokinetics in practical field problems is more recent, but is still quite mature. Most developments in the fundamental understanding of electrokinetics have been in the colloid science literature. A significant and increasing divergence between the theoretical understanding of electrokinetics found in the colloid science literature and the theoretical analyses used in interpreting applied experimental studies in soil science and waste remediation has developed. The soil science literature has to data restricted itself to the use of very early theories, with their associated limitations. The purpose of this contribution is to review fundamental aspects of electrokinetic phenomena from a colloid science viewpoint. It is hoped that a bridge can be built between the two branches of the literature, from which both will benefit. Attention is paid to special topics such as the effects of overlapping double layers, applications in unsaturated soils, the influence of dispersivity, and the differences between electrokinetic theory and conductivity theory.

Kozak, M.W.

1991-12-31

16

Synergistic effects of bioremediation and electrokinetics in the remediation of petroleum-contaminated soil.  

PubMed

The present study evaluated the coupling interactions between bioremediation (BIO) and electrokinetics (EK) in the remediation of total petroleum hydrocarbons (TPH) by using bio-electrokinetics (BIO-EK) with a rotatory 2-D electric field. The results demonstrated an obvious positive correlation between the degradation extents of TPH and electric intensity both in the EK and BIO-EK tests. The use of BIO-EK showed a significant improvement in degradation of TPH as compared to BIO or EK alone. The actual degradation curve in BIO-EK tests fitted well with the simulated curve obtained by combining the degradation curves in BIO- and EK-only tests during the first 60d, indicating a superimposed effect of biological degradation and electrochemical stimulation. The synergistic effect was particularly expressed during the later phase of the experiment, concurrent with changes in the microbial community structure. The community composition changed mainly according to the duration of the electric field, leading to a reduction in diversity. No significant spatial shifts in microbial community composition and bacterial numbers were detected among different sampling positions. Soil pH was uniform during the experimental process, soil temperature showed no variations between the soil chambers with and without an electric field. PMID:24613072

Guo, Shuhai; Fan, Ruijuan; Li, Tingting; Hartog, Niels; Li, Fengmei; Yang, Xuelian

2014-08-01

17

Electrokinetic Effects on Pressure-Driven Liquid Flows in Rectangular Microchannels  

PubMed

The effects of the electrical double layer near the solid-liquid interface and the induced electrokinetic field on the pressure-driven liquid flow through a rectangular microchannel are analyzed in this work. A nonlinear, two-dimensional Poisson-Boltzmann equation governing the electrical double layer field in the cross section of rectangular channels is numerically solved with the use of a finite-difference scheme. A body force caused by the electrical double field and the flow-induced electrokinetic field is considered in the equation of motion. An exact solution to this equation of motion in rectangular microchannels is obtained by employing the Green function formulation. The effects of the ionic concentration of the liquid, the zeta potential of the solid surface, and the size and the shape of microchannels on the fluid velocity distribution, streaming potential, volumetric flow rate, friction coefficient, and apparent viscosity are discussed. The results clearly show that for a liquid solution of low ionic concentration and a solid surface of high zeta potential the liquid flow in rectangular microchannels is significantly influenced by the presence of the electrical double layer field and hence deviates from the flow characteristics described by classical fluid mechanics. Copyright 1997 Academic Press. Copyright 1997Academic Press PMID:9367589

Yang; Li

1997-10-01

18

An electrokinetic pressure sensor  

NASA Astrophysics Data System (ADS)

A new concept for a micro pressure sensor is demonstrated. The pressure difference between the inlet and the outlet of glass nanochannels is obtained by measuring the electrokinetically generated electric potential. To demonstrate the proposed concept, experimental investigations are performed for 100 nm wide nanochannels with sodium chloride solutions having various concentrations. The proposed pressure sensor is able to measure the pressure difference within a 10% deviation from linearity. The sensitivity of the electrokinetic pressure sensor with 10-5 M sodium chloride solution is 18.5 µV Pa-1, which is one order of magnitude higher than that of typical diaphragm-based pressure sensors. A numerical model is presented for investigating the effects of the concentration and the channel width on the sensitivity of the electrokinetic pressure sensor. Numerical results show that the sensitivity increases as the concentration decreases and the channel width increases.

Kim, Dong-Kwon; Kim, Duckjong; Kim, Sung Jin

2008-05-01

19

Higher-order lattice Boltzmann simulation of energy conversion of electrokinetic nanobatteries  

NASA Astrophysics Data System (ADS)

As a novel green technology to harvest electric power, electrokinetic batteries appeal to more theoretical investigation in order to optimize their physical parameters, and hence to achieve higher energy conversion efficiency at nanoscales as expected. Generally, transport phenomena at nanoscales are out of the scope of continuum fluid mechanics theories. In addition, the electric double layer (EDL) requires a more comprehensive description incorporating image effect and ion size effect. In this study, the higher-order Lattice Boltzmann method (LBM) and the modified Poisson-Boltzmann theory (MPB) are used to investigate electrokinetic phenomena in nanochannels. Energy conversion is studied in terms of ion size, and dielectric properties of liquid and solid. 24.95% mechanical-electrical energy conversion efficiency may be achieved in a 16 nm electrokinetic battery. And hence about 6% mechanical energy can be utilized by the external load of the electrokinetic nanobattery.

Liu, Y.; Yang, J.

2009-04-01

20

Electrokinetic effects in catalytic platinum-insulator Janus swimmers  

NASA Astrophysics Data System (ADS)

The effect of added salt on the propulsion of Janus platinum-polystyrene colloids in hydrogen peroxide solution is studied experimentally. It is found that micromolar quantities of potassium and silver nitrate salts reduce the swimming velocity by similar amounts, while leading to significantly different effects on the overall rate of catalytic breakdown of hydrogen peroxide. It is argued that the seemingly paradoxical experimental observations could be theoretically explained by using a generalised reaction scheme that involves charged intermediates and has the topology of two nested loops.

Ebbens, S.; Gregory, D. A.; Dunderdale, G.; Howse, J. R.; Ibrahim, Y.; Liverpool, T. B.; Golestanian, R.

2014-06-01

21

Electrokinetic effect in the near-surface layers of the Earth  

Microsoft Academic Search

The electric field in the near-surface layers of a spherically symmetrical Earth was calculated. This electric field is generated by electrokinetic processes in a water-saturated porous medium deformed by lunisolar tides. An exact analytical solution of the Frenkel' equations describing electrokinetic phenomena is found. Data of observations of the horizontal components of the electric field are processed. The main harmonics

M. B. Gokhberg; N. I. Kolosnitsyn; V. M. Lapshin

2009-01-01

22

Effects of electrokinetic treatment of contaminated sludge on migration and transformation of Cd, Ni and Zn in various bonding states.  

PubMed

This study assesses the effect of electrokinetic processes on the migration and bonding states of various heavy metals in municipal sludge. The transformation and migration are discussed through the examination of sludge characteristics and distribution of Cd, Zn and Ni after electrokinetic treatments. The migration and distribution of the contaminants after the electrokinetic treatments were determined for each sludge sample by sequential extraction. The noticeable changes on the average speciation fractions of Cd, Zn and Ni were observed that oxidizable heavy metals increased and reducible fraction decreased due to the application of voltage. Bivariate correlation analysis indicated that the amounts of different bonding states of Zn and Ni were significantly correlated (P<0.05) with durations and resistance. The oxidizable Zn was negatively correlated with exchangeable and reducible Zn. Moreover, reducible Zn had a close negative relationship with residual Zn. The bonding state of Ni was significantly related to the durations of electrokinetic processes, indicating the existing of mutual transformation between different speciation fractions over time. The analysis also indicated that the exchangeable Cd showed a close negative relationship with reducible Cd (P<0.01), whereas the reducible Cd was negatively related to residual Cd (P<0.05). PMID:24080010

Gao, Jie; Luo, Qi-Shi; Zhu, Jiang; Zhang, Chang-Bo; Li, Bing-Zhi

2013-11-01

23

Electrokinetic pump  

SciTech Connect

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

24

Electrokinetic effect in the near-surface layers of the Earth  

Microsoft Academic Search

The electric field in the near-surface layers of a spherically symmetrical Earth was calculated. This electric field is generated\\u000a by electrokinetic processes in a water-saturated porous medium deformed by lunisolar tides. An exact analytical solution of\\u000a the Frenkel’ equations describing electrokinetic phenomena is found. Data of observations of the horizontal components of\\u000a the electric field are processed. The main harmonics

M. B. Gokhberg; N. I. Kolosnitsyn; V. M. Lapshin

2009-01-01

25

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

26

Mechanical and electrokinetic effects of polyamines/phospholipid interactions in model membranes.  

PubMed

The mechanical and electrical properties of phospholipids layers influenced by interaction with polyamines were determined by measuring surface pressure and compression modulus of monolayers and zeta potential of liposomes. The saturated derivative of phosphatidic acid (DPPA) formed layers of the organization varying with compression degree. Contact of DPPA layers with polyamines present in the subphase resulted in changing their mechanical properties and the conditions in which the layer reorganization appears. The parameters corresponding to the layer reorganization depended on the size and charge of polyamines' molecules. The values of: area per DPPA molecule, surface pressure at the point of layer structure reorganization, and surface pressure at the point of collapse characterizing of DPPA layers in the studied systems were determined. It was found that polyamines influenced to a much lesser extent the mechanical properties of monolayers formed from unsaturated derivative of phosphatidic acid slightly increasing its mechanical resistance in the range of higher molecular packing. The results of electrokinetic measurements revealed that surface charge of phosphatidic acid liposomes was effectively neutralized in the presence of polyamines. A similar effect was observed for phosphatidyl glycerol and for negatively charged polystyrene latex particles used as a reference. The influence of polyamines on the mechanical properties of DPPA layers was interpreted assuming a possibility of penetration of the lipid layer by polyamines' molecules. Comparison of action of putrescine and calcium ions and effects of polyamines on phosphatidyl glycerol provided additional justification for the proposed interpretation of the observed effects. PMID:24337467

Rudolphi-Skórska, El?bieta; Zembala, Maria; Filek, Maria

2014-01-01

27

[Effects of ionic liquids on micellar microstructures and separation performance in micellar electrokinetic chromatography].  

PubMed

The effects of ionic liquids on micellar microstructures and separation performance in micellar electrokinetic chromatography (MEKC) were investigated. The experimental results showed that the addition of ionic liquids into micellar system would result in a decreased micellar surface charge density, an enlarged size of micelle and a slight enhancement of the polarity in the inner core of micelle. Prednisone, hydrocortisone and prednisolone were analyzed with MEKC to evaluate the separation performance. Hydrocortisone and prednisolone could not be separated in sodium lauryl sulfate (SDS) micellar system. However, the three analytes could be baseline separated in the mixed system of ionic liquids and SDS (20 mmol/L SDS-10 mmol/L 1-butyl-3-methyl imidazolium tetrafluoroborate-50 mmol/L borax, pH 8.4) within 17 min. Notably, the linearities of the three analytes ranged from 2 to 100 mg/L and the detection limits based on the ratio of signal to noise of 3 were 1.0, 1.1 and 1.0 mg/L for prednisone, hydrocortisone and prednisolone, respectively. The method has been used in the analysis of corticosteroids in cosmetic samples. The recoveries for the three analytes were between 95. 1% and 117%. This method has the advantages of simple pretreatment, high accuracy, good reproducibility, and can be applied to the quality control of cosmetics. PMID:21598512

Yu, Meijuan; Hang, Dong; Cao, Yuhua

2011-02-01

28

Effect of ionic strength on electrokinetic properties of oil\\/water emulsions with dipalmitoylphosphatidylcholine  

Microsoft Academic Search

Extensive investigations of electrokinetic properties of emulsions and suspensions deal among other things with the application of natural stabilizers. Dipalmitoylphosphatidylcholine (DPPC) is present in many biochemical processes including living organisms. In this paper the dynamic properties of n-tetradecane\\/water emulsions were studied in the presence of DPPC which changes the interfacial free energy and the zeta potential. The zeta potential of

Agnieszka Ewa Wi?cek

2007-01-01

29

Preliminary results from the investigation of thermal effects in electrokinetics soil remediation  

Microsoft Academic Search

Electrokinetics is an emerging soil remediation technology. Contaminants are extracted from the soil as a result of a complex set of phenomena that occur when an electric gradient is imposed across a soil-water system. The primary phenomena include electroosmosis, electromigration, and electrophoresis. Secondary phenomena, such as changes in solubility or speciation of various chemical components, may occur as a result

T. R. Krause; B. Tarman

1993-01-01

30

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

31

Assessing effect of electrode configuration on the efficiency of electrokinetic remediation by sequential extraction analysis.  

PubMed

The electroremediation experiments were conducted on artificially polluted soils by introducing a single metallic contaminant (Pb, Zn and Cu) and multiple metallic contaminants (Pb+Zn+Cu). Based on sequential extraction results, it was observed that the removal efficiencies of lead, zinc and copper vary depending on types of contamination. When the soil was contaminated only by lead, the removal efficiency was found to be 48%. However, the removal efficiency of lead decreased to 32% when the soil was contaminated by the combination of lead, zinc and copper. Similar results were observed for zinc and copper. The corresponding removal efficiency values for zinc and copper were 92% and 37%, and 34% and 31%, respectively. Effects of electrode geometry on the removal efficiency of metals were investigated by constructing a multiple anode arrangement. In this arrangement, the electrokinetic unit consists of three cylinders, which lie one inside the other, and the soil was placed in the middle cylinder. The central cylinder was the cathode well and the outer cylinder was the anode well, where eight identical anode electrodes were placed in octagonal with respect to the cathode electrode. By using this electrode arrangement in removal of metals from the soil contaminated with the combination of three metals (Pb+Zn+Cu), the removal efficiencies of lead, zinc and copper were found to be 29%, 18% and 18%, respectively. As it can be seen, these numerical values are much lower than the values that were obtained when the traditional two-plate electrode arrangement used in the electroremediation experiments (32%, 37% and 31%). PMID:15752862

Turer, D; Genc, A

2005-03-17

32

The hindering effect of experimental strategies on advancement of alkaline front and electroosmotic flow during electrokinetic lake sediment treatment.  

PubMed

The current study focused on the hindering of alkaline front during electrokinetic copper migration in artificially contaminated lake sediments and the effect of several experimental strategies on electroosmotic flow. Fourteen laboratory scale experiments in triplicates were performed using plastic container where the distance between electrodes was 30 cm at 40 mA, 60 mA and 120 mA electric currents (under density of 0.15 mA cm(-2), 0.23 mA cm(-2) and 0.53 mA cm(-2), respectively) with different Cu concentrations (500 mg kg(-1), 1000 mg kg(-1), 1500 mg kg(-1), 2000 mg kg(-1) and 2500 mg kg(-1)) for 14 days. Tests were conducted with/without electric current and with/without the employment of membranes or barriers. Selected membranes and barriers proved to be efficient in hindering the alkaline front and thus improving copper migration in the sediments. During electrokinetic treatment and the use of the nylon membrane 85% of Cu was removed from sediments. Additionally, 80% and 70% of Cu was removed when cation exchange membrane and filter paper barrier were used. During the electrokinetic treatment Cu as well as the electroosmotic flow was always directed towards the cathode. The highest electroosmotic flow was observed with the lowest (500 mg kg(-1)) Cu concentration. Moreover, the electroosmotic flow and electrical gradient increased with the increase in electric current and was found to be the highest at 120 mA. When there were no membranes, barriers or acid used, severe pH jump was observed at a normalized distance of 0.5-0.6 from the anode. However, when membranes or barriers were employed, there was no pH jump present in the sediments. PMID:17276595

Virkutyte, Jurate; Sillanpää, Mika

2007-05-17

33

The significance of the solid-to-liquid ratio in the electrokinetic studies of the effect of ionic surfactants on mineral oxides.  

PubMed

The effect of SDS on the electrokinetic behavior of TiO(2) and Al(2)O(3) was studied by electrophoresis at various solid-to-liquid ratios. Additionally, the effect of CTAB on electrokinetic curves of Al(2)O(3) single crystal and of Al(2)O(3) particles was studied by streaming potential. At a sufficiently low solid-to-liquid ratio, the electrokinetic potential was negative and almost pH-independent in the presence of SDS and positive and pH-independent in the presence of CTAB. Further decrease in the solid-to-liquid ratio had a limited effect on the course of the electrokinetic curves. At a sufficiently high solid-to-liquid ratio, the electrokinetic potential was not affected by the presence of the surfactant. At moderate solid-to-liquid ratios, the electrokinetic potential in the presence of SDS was negative and almost pH-independent at very high and at very low pH, and less negative or even positive electrokinetic potential (more positive at higher solid-to-liquid ratios) was observed at moderate pH with a peak 1 to 2 pH units below the pristine IEP. The inspection of the results (obtained at single solid-to-liquid ratio) from the literature confirmed the above trends, also for oxides other than TiO(2) or Al(2)O(3). The range of solid-to-liquid ratios, which can be covered by electrophoresis is limited by insufficient signal, and by insufficient transparency at low and at high solid-to-liquid ratios, respectively. The available range of solid-to-liquid ratios can be extended by using the electroacoustic method. Apparently, the significance of the solid-to-liquid ratio in the electrokinetic studies of oxide-ionic surfactant systems is underrated. To our best knowledge, this is the first systematic study of such an effect ever published, and in many publications, the solid-to-liquid ratio was not reported and probably not even controlled. PMID:23195773

M?czka, Edward; Luetzenkirchen, Johannes; Kosmulski, Marek

2013-03-01

34

The Surface Charge Density Influence on the Electrokinetic Properties of Model Colloids: Solvent Composition Effect.  

PubMed

This paper deals with two problems found in electrokinetics, the anomalous behavior exhibited by most polymer colloids and the discrepancy between the zeta potentials obtained from different electrokinetic phenomena. Electrophoretic mobility for dilute dispersions and streaming current for concentrated dispersions are used to determine the zeta-potential. Two systems with different features (particle radius and surface charge density) have been studied. The influence of varsigma0 on the above-mentioned problems seems to be very important. In order to test this hypothesis, different nonaqueous media were used, which were significantly different in several liquid media properties (such as bulk conductivity, dielectric constant, and viscosity) and particle properties (such as surface charge density). Copyright 1999 Academic Press. PMID:10339365

El-Gholabzouri; Cabrerizo; Hidalgo-Álvarez

1999-06-15

35

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

2013-11-15

36

Generalized Onsager relations for electrokinetic effects in anisotropic and heterogeneous geometries  

NASA Astrophysics Data System (ADS)

We lay down a general formalism to describe the linear electrohydrodynamic response of systems of arbitrary topology, symmetry and heterogeneity, and through an explicit proof, we demonstrate a set of general Onsager relations between the corresponding electrokinetic coefficients. This generalizes a classical result of Mazur and Overbeek [P. Mazur and J.T.G. Overbeek, Recl. Trav. Chim. Pays-Bas. 70, 83 (1951)] to situations that may become of practical relevance in particular in the field of microfluidic devices. Technically, our proof of the symmetry of the generalized conductance matrix relies on an adaptation of the reciprocal theorem of low-Reynolds-number hydrodynamics.

Brunet, Edouard; Ajdari, Armand

2004-01-01

37

Nonlinear Dynamics of Electrokinetic Instabilities  

NASA Astrophysics Data System (ADS)

Electrokinetic instabilities (EKI) are caused by a coupling of electric fields and ionic conductivity gradients. Electrokinetic flows become unstable when the advection of conductivity fields due to electric body forces dominates over the dissipative effects of viscosity and molecular diffusion. EKI's are relevant to on-chip electrokinetic flows with conductivity gradients such as FASS, multi-dimensional assay devices, and sample streams with poorly specified chemistry. Here, we present an experimental study of the nonlinear fluid flow and mixing dynamics of convective electrokinetic instabilities. This experimental study was performed in a cross-pattern chip with 50 ?m wide microchannels. We obtained instantaneous concentration fields of electrically neutral, rhodamine B dye using epifluorescence microscopy and DC applied electric fields. When a critical electric Rayleigh number is exceeded, sinuous scalar patterns develop and advect downstream resulting in a single spectral peak at ? = 42 sec-1. As the applied electric field increases above a critical value, the flow exhibits sub-harmonics and higher-order harmonics, frequency bifurcations, and continuous power spectra. We will also show spatiotemporal concentration maps that exhibit strong aperiodicity. These flow phenomena are consistent with strong nonlinear dynamics and chaos.

Posner, Jonathan; Santiago, Juan

2005-11-01

38

Electrokinetic Flow in a Wavy Channel  

Microsoft Academic Search

An electrokinetic model for microfluidic flow has been developed. The effects of surface waviness of the channel wall on a pressure-driven flow have been investigated. Current analysis considers a cylindrical microchannel of finite length, having two reservoirs at ends. Poisson-Nernst-Planck and Navier-Stokes equations constitute the electrokinetic model. Significant influence of the concentration boundary condition, at the reservoir exit plane, on

Noor Al Quddus; Subir Bhattacharjee; Walied A. Moussa

2005-01-01

39

Electrokinetic Properties of Vermiculite and Expanded Vermiculite: Effects of pH, Clay Concentration and Mono and Multivalent Electrolytes  

Microsoft Academic Search

In this study, the zeta potential values of vermiculite and expanded vermiculite were measured to determine the effect of pH, clay concentration, and various mono- and multivalent electrolytes including NaCl, KCl, NH4Cl, NaNO3, NaClO4, Na2SO4, Na2CO3, Na3PO4·12H2O, MgCl2·6H2O, CaCl2·2H2O, BaCl2, SrCl2·6H2O, CuCl2·2H2O, CoCl2·6H2O, NiCl2, AlCl3, and CrCl3·6H2O on the electrokinetic properties of vermiculite samples. It was found that generally the

Osman Duman; Sibel Tunç

2008-01-01

40

Lead (II) removal from natural soils by enhanced electrokinetic remediation  

Microsoft Academic Search

Electrokinetic remediation is a very effective method to remove metal from fine-grained soils having low adsorption and buffering capacity. However, remediation of soil having high alkali and adsorption capacity via the electrokinetic method is a very difficult process. Therefore, enhancement techniques are required for use in these soil types.In this study, the effect of the presence of minerals having high

Ahmet Altin; Mustafa Degirmenci

2005-01-01

41

Microemulsion electrokinetic chromatography of proteins  

Microsoft Academic Search

Microemulsion electrokinetic chromatography was used to separate a test mixture of proteins effectively. The separation was carried out in a 42.5 cm (to the detector)×50 ?m I.D. fused-silica capillary using a microemulsion system consisting of 80 mM heptane, 120 mM SDS, 900 mM butanol in 2.5 mM borate buffer, pH 8.5–9.5. Optimum separation conditions were investigated with respect to the

Guo-Hua Zhou; Guo-An Luo; Xiao-Dang Zhang

1999-01-01

42

AC Electrokinetic Phenomena Generated by Microelectrode Structures  

PubMed Central

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 ways1, 2. 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 diagnostics3-5, environmental monitoring6 and homeland security7. 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.

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

2008-01-01

43

Electrokinetic pumps and actuators  

SciTech Connect

Flow and ionic transport in porous media are central to electrokinetic pumping as well as to a host of other microfluidic devices. Electrokinetic pumping provides the ability to create high pressures (to over 10,000 psi) and high flow rates (over 1 mL/min) with a device having no moving parts and all liquid seals. The electrokinetic pump (EKP) is ideally suited for applications ranging from a high pressure integrated pump for chip-scale HPLC to a high flow rate integrated pump for forced liquid convection cooling of high-power electronics. Relations for flow rate and current fluxes in porous media are derived that provide a basis for analysis of complex microfluidic systems as well as for optimization of electrokinetic pumps.

Phillip M. Paul

2000-03-01

44

Hybrid electrokinetic manipulation in high-conductivity media†  

PubMed Central

This study reports a hybrid electrokinetic technique for label-free manipulation of pathogenic bacteria in biological samples toward medical diagnostic applications. While most electrokinetic techniques only function in low-conductivity buffers, hybrid electrokinetics enables effective operation in high-conductivity samples, such as physiological fluids (~1 S m?1). The hybrid electrokinetic technique combines short-range electrophoresis and dielectrophoresis, and long-range AC electrothermal flow to improve its effectiveness. The major technical hurdle of electrode instability for manipulating high conductivity samples is tackled by using a Ti–Au–Ti sandwich electrode and a 3-parallel-electrode configuration is designed for continuous isolation of bacteria. The device operates directly with biological samples including urine and buffy coats. We show that pathogenic bacteria and biowarfare agents can be concentrated for over 3 orders of magnitude using hybrid electrokinetics.

Gao, Jian; Sin, Mandy L. Y.; Liu, Tingting; Gau, Vincent; Liao, Joseph C.

2014-01-01

45

Electrokinetic recovery of Cd, Cr, As, Ni, Zn and Mn from waste printed circuit boards: effect of assisting agents.  

PubMed

The printed circuit boards (PCBs) contains large number of heavy metal such as Cd, Cr, As, Ni, Zn and Mn. In this study, the use of electrokinetic (EK) treatment with different assisting agents has been investigated to recover the heavy metals from waste PCBs, and the effectiveness of different assisting agents (HNO(3), HCl, citric acid) was evaluated. The PCBs were first pre-treated by supercritical water oxidation (SCWO) process, then subjected to EK process. The heavy metal speciation, migration and recovery efficiency in the presence of different assisting agents during EK process were discussed. The mass loss of Cd, Cr, As and Zn during the SCWO process was negligible, but approximately 52% of Ni and 56% of Mn were lost in such a process. Experimental results showed that different assisting agents have significant effect on the behavior and recovery efficiency of different heavy metals. HCl was highly efficient for the recovery of Cd in waste PCBs due to the low pH and the stable complexation of Cl(-). Citric acid was highly efficient for the recovery of Cr, Zn and Mn. HNO(3) was low efficient for recovery of most heavy metals except for Ni. PMID:19481346

Xiu, Fu-Rong; Zhang, Fu-Shen

2009-10-15

46

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

47

Experimental and numerical investigation into the joule heating effect for electrokinetically driven microfluidic chips utilizing total internal reflection fluorescence microscopy  

Microsoft Academic Search

This paper presents a detection scheme for analyzing the temperature distribution nearby the channel wall in a microfluidic\\u000a chip utilizing a temperature-dependent fluorescence dye. An advanced optical microscope system—total internal reflection fluorescence\\u000a microscope (TIRFM) is used for measuring the temperature distribution on the channel wall at the point of electroosmotic flow\\u000a in an electrokinetically driven microfluidic chip. In order to

Lung-Ming Fu; Jing-Hui Wang; Wen-Bo Luo; Che-Hsin Lin

2009-01-01

48

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

49

Electrokinetic remediation of contaminated soils  

SciTech Connect

Electrokinetic remediation of contaminated soil has been demonstrated for saturated and unsaturated sand in preliminary experiments using a novel transport visualization technique. Large anionic organic dyes were mixed with a portion of soil and the rate of electromigration of the dye in an imposed electric field was monitored photographically. One of the fastest current-normalized electromigration rates was measured in the driest sand, which contained 7% water by weight. This moisture content is typical of the moisture content in the unsaturated zone of subsurface native soils found in New Mexico. The characteristics of the electromigration were similar in both the saturated and unsaturated sand. The leading edge of the dye migration front was diffuse while the trailing edge was sharp and concentrated. This and other observed behavior may indicate a concentration effect, where the electromigration rate of dilute dye is greater than that of concentrated dye. The soil left after the trailing edge passed seemed to contain no residual dye in both the saturated and unsaturated cases. The success of demonstrating electromigration of large molecules in unsaturated soil is encouraging and indicates that it may be feasible to remediate in situ anionic heavy metals such as chromate from unsaturated soil with electrokinetic techniques. 23 refs., 7 figs.

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

1991-01-01

50

Integrated electrokinetics-adsorption remediation of saline-sodic soils: effects of voltage gradient and contaminant concentration on soil electrical conductivity.  

PubMed

In this study, an integrated in situ remediation technique which couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic clay soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the effects of voltage gradient, initial contaminant concentration, and polarity reversal rate on the soil electrical conductivity. Box-Behnken Design (BBD) was used for the experimental design and response surface methodology (RSM) was employed to model, optimize, and interpret the results obtained using Design-Expert version 8 platform. The total number of experiments conducted was 15 with voltage gradient, polarity reversal rate, and initial contaminant concentration as variables. The main target response discussed in this paper is the soil electrical conductivity due to its importance in electrokinetic remediation process. Responses obtained were fitted to quadratic models whose R (2) ranges from 84.66% to 99.19% with insignificant lack of fit in each case. Among the investigated factors, voltage gradient and initial contaminant concentration were found to be the most significant influential factors. PMID:24459439

Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat; Lukman, Salihu; Bukhari, Alaadin

2013-01-01

51

Desalination of porous building materials by electrokinetics: an NMR study  

Microsoft Academic Search

This article presents the first non destructive measurements of salt ions transport through fired-clay brick during electrokinetic\\u000a desalination using nuclear magnetic resonance technique. The effect of the strength of an applied electric field on the migration\\u000a of salt ions is examined by varying the electrical potential gradients from 0.75–2 V cm?1 across the specimens. The measurements show that for electrokinetic to exceed

Kashif Kamran; Leo Pel; Alison Sawdy; Henk Huinink; Klaas Kopinga

52

Alternating current electrokinetic motion of colloidal particles on interdigitated microelectrodes.  

PubMed

Alternating current (ac) electrokinetic motion of colloidal particles suspended in an aqueous medium and subjected to a spatially nonuniform ac electric field are examined using a simple theoretical model that considers the relative magnitudes of dielectrophoresis, electrophoresis, ac-electroosmosis, and Brownian motion. Dominant electrokinetic forces are explained as a function of the electric field frequency, amplitude, and conductivity of the suspending medium for given material properties and geometry. Parametric experimental validations of the model are conducted utilizing interdigitated microelectrodes with polystyrene and gold particles and Clostridium sporogenes bacterial spores. The theoretical model provides quantitative descriptions of ac electrokinetic transport for the given target species in a wide spectrum of electric field amplitude and frequency and medium conductivity. The presented model can be used as an effective framework for design and optimization of ac electrokinetic devices. PMID:18318510

Park, Seungkyung; Beskok, Ali

2008-04-15

53

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

2012-11-21

54

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

55

Electrokinetic migration studies on removal of chromium and uranyl ions from 904-A trench soil  

SciTech Connect

This report describes a laboratory-scale study, in which electrokinetic migration technology was used to remove chromium and uranium, as well as other ions, from soil taken from a bore hole adjacent to the 904-A trench at the Savannah River Technology Center. Imposition of an electric current on humid (not saturated) soil successfully caused cations to migrate through the pore water of the soil to the cathode, where they were captured in an ISOLOCKTm polymer matrix and in a cation exchange resin incorporated in the polymer. Chemicals circulated through the anode/polymer and cathode/polymer were able to control pH excursions in the electrokinetic-cells by reacting with the H{sup +} and OH{sup {minus}} generated at the anode and cathode, respectively. The study indicates that ions adsorbed on the surface of the soil as well as those in the pores of soil particles can be caused to migrate through the soil to an appropriate electrode. After 10 days of operation at 20--25 V and 2 mA, approximately 65% of the chromium was removed from two 3.5 kg soil samples. A 57% removal of uranium was achieved. The study shows that electrokinetic migration, using the ISOLOCK{trademark} polymer will be effective as an in situ treatment method for the removal of metal ion contaminants in soil adjacent to the 904-A trench.

Bibler, J.P.; Meaker, T.F.; O`Steen, A.B.

1992-09-30

56

Effect of polyelectrolyte mixtures on the electrokinetic potential and kinetics of flocculation of clay mineral particles  

Microsoft Academic Search

The effect of binary mixtures of cationic and anionic electrolytes on the kinetics of aggregation, size and strength of flocs formed from kaolin and bentonite particles as a function of the polymer dose, mixture composition, sequence of the components addition and intensity of stirring the system has been studied. A synergism in the flocculation capacity in mixtures of moderate and

S. Bárány; R. Meszaros; L. Marcinova; J. Skvarla

2011-01-01

57

Electrokinetic high pressure hydraulic system  

Microsoft Academic Search

A compact high pressure hydraulic pump having no moving mechanical parts for converting electric potential to hydraulic force is described. The electrokinetic pump, which can generate hydraulic pressures greater than 2,500 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

P. H. Paul; D. J. Rakestraw

2000-01-01

58

Electrokinetic high pressure hydraulic system  

Microsoft Academic Search

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

Phillip H. Paul; David J. Rakestraw

2000-01-01

59

Analysis of electrokinetic effects on the liquid flow in rectangular microchannels  

Microsoft Academic Search

The effects of the electrical double layer near the solid\\/liquid interface on liquid flow through a rectangular microchannel are analyzed in this work. Based on the Debye–Hückel approximation, a linear solution of a two-dimensional Poisson–Boltzmann equation governing the electrical potential distribution in the cross-section of rectangular channels is presented to describe the electrical double-layer field near the solid\\/liquid interface. An

Chun Yang; Dongqing Li

1998-01-01

60

Electrode kinetic and electro-kinetic effects in electroosmotic dewatering of clay suspensions  

SciTech Connect

Lockhart`s remarks on the author`s previous interpretation of the electrochemical aspects of the electroosmotic dewatering (EOD) of clay suspensions are analyzed to provide some further clarification. Based on Lockhart`s excellent work, the authors put forward here novel electrochemical interpretations of some features of the following experimental observations: (1) Galvani dewatering; (2) the dewatering efficiency; and (3) high voltage needed for dewatering Al-kaolinite and aluminum electrode effect.

Vijh, A.K. [Inst. de Recherche d`Hydro-Quebec, Varennes, Quebec (Canada)

1997-05-01

61

Colloidal particle deposition from electrokinetic flow in a microfluidic channel.  

PubMed

This study reports a theoretical and experimental study on the irreversible deposition of colloidal particles from electrokinetic microfluidic flow. The electrokinetic particle transport model presented in this study is based on the stochastic Langevin equation, incorporating the electrical, hydrodynamic, Derjaguin-Landau-Verwey-Overbeek colloidal interactions and random Brownian motion of colloidal particles. Brownian dynamics simulation is used to compute the particle deposition in terms of the surface coverage. Direct videomicroscopic observation using the parallel-plate flow cell technique is employed to determine the deposition kinetics of polystyrene latex particles in NaCl electrolytes. The theoretical predictions are compared with experimental results, and a reasonable agreement is found. PMID:19260008

Unni, Harikrishnan Narayanan; Yang, Chun

2009-03-01

62

Electrokinetics in microfluidic channels containing a floating electrode.  

PubMed

Electrokinetic transport within a buffer-filled microchannel incorporating a flat bipolar electrode is investigated. The key finding is that the presence of the electrode disrupts the passage of electrical current through the microchannel and thereby alters the uniformity of the local electric field. Electroosmotic flow further modulates the local field gradient. These dynamics are demonstrated experimentally by utilizing the field gradient for concentration enrichment of negatively charged tracer molecules, and a set of computer simulations is presented to interpret the underlying electrokinetics. PMID:18642919

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

2008-08-13

63

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

2010-01-01

64

AC electrokinetics: applications for nanotechnology  

NASA Astrophysics Data System (ADS)

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 the principles of AC electrokinetics for particle manipulation, review the current state of AC electrokinetic techniques for the manipulation of particles on the nanometre scale, and consider how these principles may be applied to nanotechnology.

Pycraft Hughes, Michael

2000-06-01

65

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

66

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

67

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

68

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

69

Comparative study of simultaneous removal of As, Cu, and Pb using different combinations of electrokinetics with bioleaching by Acidithiobacillus ferrooxidans.  

PubMed

Different designs of electrokinetics were applied to simultaneously remove arsenic, copper, and lead from contaminated soils. Single electrokinetics (control) resulted in superior removal efficiencies for Cu (73.5%) and Pb (88.5%), though the removal of As (3.11%) was relatively little. Sequential bioelectrokinetics of bioleaching with Acidithiobacillus ferrooxidans and electrokinetics enhanced the removal of As (25%), while Pb exhibited a significant decrease in removal efficiency (10.6%), due to the formation of insoluble compounds. In order to improve the overall performance, integrated bioelectrokinetics was designed by inoculating A. ferrooxidans into the electrolyte after 5 or 15 days of electrokinetics. Lead (75.8%) and copper (72%) were effectively removed through electrokinetics, after which arsenic (35%) was more efficiently removed by bioleaching-enhanced electrokinetics. A pilot-scale experiment indicated that integrated bioelectrokinetics is an effective means of remediation of soils contaminated with multiple heavy metals and arsenic. PMID:22921395

Kim, Hyun-A; Lee, Keun-Young; Lee, Byung-Tae; Kim, Soon-Oh; Kim, Kyoung-Woong

2012-11-01

70

Removal of fluorine from contaminated soil by electrokinetic treatment driven by solar energy.  

PubMed

Instead of direct current power supply, a series of electrokinetic remediation experiments driven by solar energy on fluorine-contaminated soil were conducted in a self-made electrolyzer, in order to reduce energy expenditure of electrokinetic remediation. After the 12-day electrokinetic remediation driven by solar energy, the removal efficiency of fluorine was 22.3%, and electrokinetic treatment had an impact on changes in partitioning of fluorine in soil. It proved that the combination of electrokinetics and solar energy was feasible and effective to some extent for the remediation of fluorine-contaminated soil. Meanwhile, the experimental results also indicated that the electromigration was a more dominant transport mechanism for the removal of fluorine from contaminated soil than electroosmosis, and the weather condition was the important factor in affecting the removal efficiency. PMID:23475445

Zhou, Ming; Zhu, Shufa; Liu, Yana; Wang, Xuejian

2013-08-01

71

Effect of linear surface-charge non-uniformities on the electrokinetic ionic-current rectification in conical nanopores.  

PubMed

The electrokinetic ionic-current rectification in a conical nanopore with linearly varying surface-charge distributions is studied theoretically by using a continuum model composed of a coupled system of the Nernst-Planck equations for the ionic-concentration field and the Poisson equation for the electric potential in the electrolyte solution. The numerical analysis includes the electrochemistry inside reservoirs connected to the nanopore, neglected in previous studies, and more precise accounts of the ionic current are provided. The surface-charge distribution, especially near the tip of the nanopore, significantly affects the ionic enrichment and depletion, which, in turn, influence the resulting ionic current and the rectification. It is shown that non-uniform surface-charge distribution can reverse the direction, or sense, of the rectification. Further insights into the ionic-current rectification are provided by discussing the intriguing details of the electric potential and ionic-concentration fields, leading to the rectification. Rationale for future studies on ionic-current rectification, associated with other non-uniform surface-charge distributions and electroosmotic convection for example, is discussed. PMID:18977486

Qian, Shizhi; Joo, Sang W; Ai, Ye; Cheney, Marcos A; Hou, Wensheng

2009-01-15

72

Electrokinetic effect of the Loma Prieta earthquake calculated by an entire-Earth FDTD solution of Maxwell's equations  

NASA Astrophysics Data System (ADS)

We report what we believe to be the first three-dimensional computational solution of the full-vector Maxwell's equations for hypothesized pre-seismic electromagnetic phenomena propagated within the entire Earth-ionosphere cavity. Periodic boundary conditions are used in conjunction with a variable-cell finite-difference time-domain (FDTD) space lattice wrapping around the complete Earth-sphere and extending +/-100 km radially from sea level. This technique permits a direct time-domain calculation of round-the-world ULF/ELF propagation accounting for arbitrary horizontal as well as vertical geometrical and electrical inhomogeneities/anisotropies of the excitation, ionosphere, lithosphere, and oceans. In this study, we model electrokinetic currents at depths of 2.5 km and 17 km near the hypocenter of the Loma Prieta earthquake and compare the FDTD-calculated surface magnetic field to analytical results and measurements previously reported in the literature. We accommodate the complete physics introduced by impulsive electromagnetic wave propagation through the conductive Earth, and hence illustrate the importance of solving the full Maxwell's equations when modeling current sources within the Earth's crust. Our calculated spectra agree qualitatively with those reported by Fraser-Smith et al. (1990).

Simpson, Jamesina J.; Taflove, Allen

2005-05-01

73

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

74

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

75

Effect of molecular structure of tartrates on chiral recognition of tartrate-boric acid complex chiral selectors in chiral microemulsion electrokinetic chromatography.  

PubMed

Eight l-tartrates and a d-tartrate with different alcohol moieties were used as chiral oils to prepare chiral microemulsions, which were utilized in conjunction with borate buffer to separate the enantiomers of beta-blockers or structurally related compounds by the chiral microemulsion electrokinetic chromatography (MEEKC) method. Among them, six were found to have a relatively good chiral separation performance and their chiral recognition effect in terms of both enantioselectivity and resolution increases linearly with the number of carbon atoms in the alkyl group of alcohol moiety. The tartrates containing alkyl groups of different structures but the same number of carbon atoms, i.e. one of straight chain and one of branched chain, provide similar enantioseparations. The trend was elucidated according to the changes in the difference of the steric matching between the molecules of two enantiomers and chiral selector. Furthermore, it was demonstrated for the first time that a water insoluble solid compound, di-i-butyl l-tartrate (mp. 73.5 degrees C), can be used as an oil to prepare a stable microemulsion to be used in the chiral MEEKC successfully. And a critical effect of the microemulsion for chiral separation, which has never been reported before, was found in this experiment, namely providing a hydrophobic environment to strengthen the interactions between the chiral selector and enantiomers. PMID:20638068

Hu, Shao-Qiang; Chen, Yong-Lei; Zhu, Hua-Dong; Shi, Hai-Jun; Yan, Na; Chen, Xing-Guo

2010-08-20

76

Electrokinetic remediation of 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. Large spills and leaks can contaminate both the soil above the water table as well as the aquifer itself. Electrodes are implanted in the soil, and a direct current is imposed between the electrodes. The application of direct current leads to a number of effects: ionic species and charged particles in the soil water will migrate to the oppositely charged electrode (electromigration and electrophoresis), and concomitant with this migration, a bulk flow of water is induced, usually toward the cathode (electroosmosis). The combination of these phenomena leads to a movement of contaminants toward the electrodes. The direction of contaminant movement will be determined by a number of factors, among which are type and concentration of contaminant, soil type and structure, interfacial chemistry of the soil-water system, and the current density in the soil pore water. Contaminants arriving at the electrodes may potentially be removed from the soil by one of several methods, such as electroplating or adsorption onto the electrode, precipitation or co-precipitation at the electrode, pumping of water near the electrode, or complexing with ion-exchange resins. Experimental results are described on the removal of sodium dichromate and food dye from soil.

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

1992-10-01

77

Electrokinetic remediation of 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. Large spills and leaks can contaminate both the soil above the water table as well as the aquifer itself. Electrodes are implanted in the soil, and a direct current is imposed between the electrodes. The application of direct current leads to a number of effects: ionic species and charged particles in the soil water will migrate to the oppositely charged electrode (electromigration and electrophoresis), and concomitant with this migration, a bulk flow of water is induced, usually toward the cathode (electroosmosis). The combination of these phenomena leads to a movement of contaminants toward the electrodes. The direction of contaminant movement will be determined by a number of factors, among which are type and concentration of contaminant, soil type and structure, interfacial chemistry of the soil-water system, and the current density in the soil pore water. Contaminants arriving at the electrodes may potentially be removed from the soil by one of several methods, such as electroplating or adsorption onto the electrode, precipitation or co-precipitation at the electrode, pumping of water near the electrode, or complexing with ion-exchange resins. Experimental results are described on the removal of sodium dichromate and food dye from soil.

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

78

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

79

Understanding fluid mechanics within electrokinetically pumped microfluidic chips  

Microsoft Academic Search

A model describing electroosmotic fluid pumping within glass microchannels is presented. Results of calculations of fluid flow within a manifold of intersecting channels are compared with experimental observations. The effect of channel length on leakage effects at electrokinetically controlled, valveless intersections is examined. The influence of changing the surface charge potential in one channel but not another is shown to

X. C. Qiu; Lianguang Hu; J. H. Masliyah; D. J. Harrison

1997-01-01

80

Electrokinetic high pressure hydraulic system  

DOEpatents

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

81

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

82

Perchlorate Remediation by Electrokinetic Extraction and Electrokinetic Injection of Substrates  

Microsoft Academic Search

Perchlorate (ClO4?) contamination of groundwater has recently become a major concern across the nation. Electrokinetic (EK) extraction with the simultaneous EK injection of organic material to promote degradation could allow for the efficient removal of perchlorate while simultaneously promoting degradation of perchlorate. Column experiments were conducted to evaluate the technology. Lactate and glycine served as organic substrates to promote degradation

W. Jackson; Mi-Ae Jeon; Todd Anderson; John Pardue

2004-01-01

83

Catalytically induced electrokinetics for motors and micropumps.  

PubMed

We have explored the role of electrokinetics in the spontaneous motion of platinum-gold nanorods suspended in hydrogen peroxide (H2O2) solutions that may arise from the bimetallic electrochemical decomposition of H2O2. The electrochemical decomposition pathway was confirmed by measuring the steady-state short-circuit current between platinum and gold interdigitated microelectrodes (IMEs) in the presence of H2O2. The resulting ion flux from platinum to gold implies an electric field in the surrounding solution that can be estimated from Ohm's Law. This catalytically generated electric field could in principle bring about electrokinetic effects that scale with the Helmholtz-Smoluchowski equation. Accordingly, we observed a linear relationship between bimetallic rod speed and the resistivity of the bulk solution. Previous observations relating a decrease in speed to an increase in ethanol concentration can be explained in terms of a decrease in current density caused by the presence of ethanol. Furthermore, we found that the catalytically generated electric field in the solution near a Pt/Au IME in the presence of H2O2 is capable of inducing electroosmotic fluid flow that can be switched on and off externally. We demonstrate that the velocity of the fluid flow in the plane of the IME is a function of the electric field, whether catalytically generated or applied from an external current source. Our findings indicate that the motion of PtAu nanorods in H2O2 is primarily due to a catalytically induced electrokinetic phenomenon and that other mechanisms, such as those related to interfacial tension gradients, play at best a minor role. PMID:17105298

Paxton, Walter F; Baker, Paul T; Kline, Timothy R; Wang, Yang; Mallouk, Thomas E; Sen, Ayusman

2006-11-22

84

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

85

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

86

Electrokinetic-enhanced bioremediation of organic contaminants: a review of processes and environmental applications.  

PubMed

There is current interest in finding sustainable remediation technologies for the removal of contaminants from soil and groundwater. This review focuses on the combination of electrokinetics, the use of an electric potential to move organic and inorganic compounds, or charged particles/organisms in the subsurface independent of hydraulic conductivity; and bioremediation, the destruction of organic contaminants or attenuation of inorganic compounds by the activity of microorganisms in situ or ex situ. The objective of the review is to examine the state of knowledge on electrokinetic bioremediation and critically evaluate factors which affect the up-scaling of laboratory and bench-scale research to field-scale application. It discusses the mechanisms of electrokinetic bioremediation in the subsurface environment at different micro and macroscales, the influence of environmental processes on electrokinetic phenomena and the design options available for application to the field scale. The review also presents results from a modelling exercise to illustrate the effectiveness of electrokinetics on the supply electron acceptors to a plume scale scenario where these are limiting. Current research needs include analysis of electrokinetic bioremediation in more representative environmental settings, such as those in physically heterogeneous systems in order to gain a greater understanding of the controlling mechanisms on both electrokinetics and bioremediation in those scenarios. PMID:24875868

Gill, R T; Harbottle, M J; Smith, J W N; Thornton, S F

2014-07-01

87

Electrokinetic confinement of axonal growth for dynamically configurable neural networks  

PubMed Central

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 105 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 Ca2+ imaging demonstrated the unidirectional nature of the synaptic connections. AC electrokinetic confinement of axonal growth has potential for creating configurable, directional neural networks.

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

2013-01-01

88

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

89

Electrokinetic treatment of contaminated soils, sludges, and lagoons. Final report  

SciTech Connect

The electrokinetic process is an emerging technology for in-situ soil decontamination, in which chemical species, both ionic and nonionic are transported to an electrode site in soil. These products are subsequently removed from the ground via collection systems engineered for each specific application. Electrokinetics refer to movement of water, ions and charged particles relative to one another under the action of an applied direct current electric field. In a porous compact matrix of surface charged particles such as soil, the ion containing pore fluid may be made to flow to collection sites under the applied field. This report describes the effort undertaken to investigate electrokinetically enhanced transport of soil contaminants in synthetic systems. These systems consisted of clay or clay-sand mixtures containing known concentration of a selected heavy metal salt solution or an organic compound. Metals, surrogate radio nuclides and organic compounds evaluated in the program were representatives of those found at a majority of DOE sites. Degree of removal of these metals from soil by the electrokinetic treatment process was assessed through the metal concentration profiles generated across the soil between the electrodes. The best removals, from about 85 to 95% were achieved at the anode side of the soil specimens. Transient pH change had an effect on the metal movement via transient creation of different metal species with different ionic mobilities, as well as changing of the surface characteristics of the soil medium.

Wittle, J.K. [Electro-Petroleum, Inc., Wayne, PA (United States); Pamukcu, S. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Civil Engineering

1993-04-01

90

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

91

Electrokinetic high pressure hydraulic system  

DOEpatents

An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based systems. The pump uses electro-osmotic flow to provide a high pressure hydraulic system, having no moving mechanical parts, for pumping and/or compressing fluids, for providing valve means and means for opening and closing valves, for controlling fluid flow rate, and manipulating fluid flow generally and in capillary-based systems (Microsystems), in particular. The compact nature of the inventive high pressure hydraulic pump provides the ability to construct a micro-scale or capillary-based HPLC system that fulfills the desire for small sample quantity, low solvent consumption, improved efficiency, the ability to run samples in parallel, and field portability. Control of pressure and solvent flow rate is achieved by controlling the voltage applied to an electrokinetic pump.

Paul, Phillip H. (Livermore, CA); Rakestraw, David J. (Fremont, CA); Arnold, Don W. (Livermore, CA); Hencken, Kenneth R. (Pleasanton, CA); Schoeniger, Joseph S. (Oakland, CA); Neyer, David W. (Castro Valley, CA)

2001-01-01

92

Extended Electrokinetic Characterization of Flat Solid Surfaces  

Microsoft Academic Search

An experimental setup has been developed and applied for the combined determination of the electrokinetic potential and the surface conductivity of flat surfaces. The key feature of the new device (designated as microslit electrokinetic setup) is the variability of the distance between two parallel flat sample surfaces (10 mm × 20 mm) forming a slit channel. The setup allows us

Carsten Werner; Heinz Körber; Ralf Zimmermann; Stanislav Dukhin; Hans-Jörg Jacobasch

1998-01-01

93

Electrokinetic dewatering of a phosphate clay  

Microsoft Academic Search

The principles of electrokinetic dewatering are: (1) electrophoresis, the movement of colloidal particles in a direct current electric field; (2) dielectrophoresis, the movement of colloidal particles in a non-uniform electric field; and (3) electro-osmosis, the water flow in porous media in a direct current electric field. Electrokinetic dewatering of a phosphate clay was investigated in an experimental program. The results

J. Q. Shang; K. Y. Lo

1997-01-01

94

The Multi-Porosity Multi-Permeability and Electrokinetic Natures of Shales and Their Effects in Hydraulic Fracturing of Unconventional Shale Reservoirs  

NASA Astrophysics Data System (ADS)

Imaging studies of unconventional shale reservoir rocks have recently revealed the multi-porosity multi-permeability nature of these intricate formations. In particular, the porosity spectrum of shale reservoir rocks often comprises of the nano-porosity in the organic matters, the inter-particle micro-porosity, and the macroscopic porosity of the natural fracture network. Shale is also well-known for its chemically active behaviors, especially shrinking and swelling when exposed to aqueous solutions, as the results of pore fluid exchange with external environment due to the difference in electro-chemical potentials. In this work, the effects of natural fractures and electrokinetic nature of shale on the formation responses during hydraulic fracturing are examined using the dual-poro-chemo-electro-elasticity approach which is a generalization of the classical Biot's poroelastic formulation. The analyses show that the presence of natural fractures can substantially increase the leak-off rate of fracturing fluid into the formation and create a larger region of high pore pressure near the fracture face as shown in Fig.1a. Due to the additional fluid invasion, the naturally fractured shale swells up more and the fracture aperture closes faster compared to an intrinsically low permeability non-fractured shale formation as shown in Fig.1b. Since naturally fractured zones are commonly targeted as pay zones, it is important to account for the faster fracture closing rate in fractured shales in hydraulic fracturing design. Our results also show that the presence of negative fixed charges on the surface of clay minerals creates an osmotic pressure at the interface of the shale and the external fluid as shown in Fig.1c. This additional Donnan-induced pore pressure can result in significant tensile effective stresses and tensile damage in the shale as shown in Fig.1d. The induced tensile damage can exacerbate the problem of proppant embedment resulting in more fracture closure and reduction of fracture length and productivity. The results also suggest that a fracturing fluid with appropriately designed salinity can minimize the chemically induced tensile damage and, thus, maximize the productivity from the created hydraulic fractures.

Liu, C.; Hoang, S. K.; Tran, M. H.; Abousleiman, Y. N.

2013-12-01

95

Enhancement of electrokinetic decontamination with EDTA.  

PubMed

The effect of ethylenediaminetetraacetic acid (EDTA) during electrokinetic decontamination (EKD) was investigated in this research. EDTA is a ligand that can form soluble complexes with precipitated heavy metals inside soil pores. Millpond sludge, primarily contaminated with lead (Pb) and zinc (Zn), was subjected to EKD with and without the presence of EDTA. Dilute EDTA solutions with strengths of 0.05 M and 0.125 M were injected into the millpond sludge by electroosmosis. Several beneficial effects of using EDTA were observed in this research. One was that the presence of EDTA substantially increased the electroosmotic (EO) flow in the millpond sludge indicating that it could significantly reduce the duration of EKD. Another advantage was that a significantly higher percentage of Pb and Zn removal was achieved from the solid phase due to the complexation of EDTA with these heavy metals. Also, EDTA was able to prevent the precipitation of metals at the cathode electrode, typically observed in EKD process. PMID:23393970

Karim, M A; Khan, L I

2012-01-01

96

Incorporating post-Newtonian effects in N-body dynamics  

NASA Astrophysics Data System (ADS)

The increasing role of general relativity in the dynamics of stellar systems with central massive black holes, in the generation of extreme mass-ratio inspirals and tidal disruption events, and in the evolution of hierarchical triple systems inspires a close examination of how post-Newtonian effects are incorporated into N-body dynamics. The majority of approaches incorporate relativity by adding to the Newtonian N-body equations the standard two-body post-Newtonian terms for a given star around the black hole or for the close binary in a triple system. We argue that, for calculating the evolution of such systems over time scales comparable to the relativistic pericenter advance time scale, it is essential to include "cross terms" in the equations of motion. These are post-Newtonian terms in the equation of motion of a given body that represent a coupling between the potential of the central black hole and the potential due to other stars in the system. For hierarchical triple systems, these are couplings between the potential of the inner binary and that of the distant third body. Over pericenter precession time scales, the effects of such terms can actually be "boosted" to amplitudes of Newtonian order. We write down the post-Newtonian N-body equations of motion including a central black hole in a truncated form that includes all the relevant cross terms, in a format ready to use for numerical implementation. We do the same for hierarchical triple systems, and illustrate explicitly the effects of cross terms on the orbit-averaged equations of evolution for the orbit elements of the inner binary for the special case where the third body is on a circular orbit. We also describe in detail the inspiration for this investigation: the seemingly trivial problem of the motion of a test body about a central body with a Newtonian quadrupole moment, including the relativistic pericenter advance, whose correct solution for the conserved total Newtonian energy requires including post-Newtonian cross terms between the mass monopole potential and the quadrupole potential.

Will, Clifford M.

2014-02-01

97

Electrokinetic properties of clinoptilolite with mono- and multivalent electrolytes  

Microsoft Academic Search

In this study, electrokinetic properties of clinoptilolite have been determined. A series of systematic zeta potential measurements have been performed to determine the isoelectric point (iep) and potential determining ions (pdi), and the effect of mono- and multivalent salts such as NH4Cl, CaCl2, Al(NO3)3 on the zeta potential of clinoptilolite. Clinoptilolite in water exhibits a negative surface charge and maintains

Bahri Ersoy; Mehmet S. Çelik

2002-01-01

98

Transport of nitrates through clay using electrokinetics  

SciTech Connect

In this paper, the results of laboratory experiments to investigate the feasibility of using electrokinetics to transport nitrates (a nutrient) through a low-permeability soil are presented. Tests were conducted using a kaolinite soil consolidated from a slurry under a vertical stress of 127 kPa. Sodium nitrate was introduced in a chamber in front of a graphite electrode that becomes the cathode in the electrokinetic process. A hydraulic head was used to reduce the osmotic pressures. The results of the tests reveal that, under laboratory conditions, nitrates can be transported through low-permeability soils using electrokinetics.

Budhu, M.; Rasmussen, W. [Univ. of Arizona, Tucson, AZ (United States); Rutherford, M.; Sills, G. [Univ. of Oxford (United Kingdom)

1997-12-01

99

Note on the Nonlinear Electrokinetic Effects in Mircochannel Flow: Exact Analytical Solutions for Sinh-Poisson Equation  

NASA Astrophysics Data System (ADS)

Electrokinectic effects are important phenomena for fluid flow in microchannels, especially in mechanical systems involving movable micromechanical devices. Electrokinectic effects arise from electric double layer, which is a layer of charges attached to the dielectric surfaces as a result of the interaction of charges between ionized solution and dielectric surfaces. Electric potential inside the flow field is governed by the nonlinear Poisson-Boltzmann equation. Owing to the difficulty in solving the nonlinear equation, Debye - Hückel approximation, having an assumption of small electric potential, is a common approach to solve the linearized problem. In the present work, exact analytical expressions are obtained for the fully nonlinear sinh - Poisson equation without invoking the linear approximation. These solutions give insight on treating flow problems when Debye - Hückel approximation does not hold. Selected examples of solutions for a rectangular cell with zero homogenous boundary conditions applied on three wall surfaces are used for comparisons between the fully nonlinear and the linearized cases. Significant discrepancies are observed if the potential is not small, hence the present nonlinear theory is essential to better describe the physics involved.

Hou Tsang, Alan Cheng; Wing Chow, Kwok

2010-11-01

100

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

101

The Effect of Thymidine Pool Size on the Incorporation of Thymidine into DNA after Irradiation.  

National Technical Information Service (NTIS)

A model system to explain the effect of irradiation on the incorporation of thymidine into deoxyribonucleic acid (DNA) was studied. The model explains the increase observed in thymidine incorporation after irradiation as due to an increase in the intracel...

D. F. Logsdon H. L. Kundel

1965-01-01

102

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...

103

Electrokinetic Remediation of Contaminated Dredged Sediment  

Microsoft Academic Search

This paper investigates the feasibility of electrokinetic remediation of contaminated sediment at Indiana Harbor, Indiana. The sediment is a fine-grained material with high moisture content of 78 % and high organic content of 19 % and it is contaminated with a wide range of polycyclic aromatic hydrocarbons PAHs and heavy metals. Four bench-scale electrokinetic experiments were conducted at 2.0 VDC\\/cm

Krishna R. Reddy; Prasanth R. Ala

2006-01-01

104

Electrokinetic Removal of Manganese from River Sediment  

Microsoft Academic Search

Manganese was removed from naturally polluted river sediment by applying an electrokinetic remediation technique. The sediment\\u000a was alkaline and had 20% clay, which was mainly illite. The electrokinetic remediation experiments were performed by controlling\\u000a pHs in the electrode cells and reverse electroosmotic flows were observed, i.e., water moved from cathode towards anode. Manganese\\u000a accumulated in areas closer to cathode, however,

Ayten Genc; George Chase; Annabelle Foos

2009-01-01

105

Selectivity in microemulsion electrokinetic chromatography.  

PubMed

Microemulsion electrokinetic chromatography (MEEKC) is a most promising separation technique providing good selectivity and high separation efficiency of anionic, cationic as well as neutral solutes. In MEEKC lipophilic organic solvents dispersed as tiny droplets in an aqueous buffer by the use of surfactants provide a pseudo-stationary phase to which the solutes may have an affinity either to the surface or they may even partition into the droplets. When the droplets are charged, typically negatively, they will migrate opposite to the electroosmotic flow and hence separation of neutral solutes may take place. In the present paper focus has been set on how to change selectivity in MEEKC. Changes in the nature of surfactant as well as in pH have been shown to be powerful tools in changing the selectivity. The type of lipophilic organic phase is of less importance for the separation of fairly lipophilic solutes. Also changes in the temperature surrounding the capillary may alter the selectivity. PMID:11128221

Pedersen-Bjergaard, S; Gabel-Jensen, C; Honoré Hansen, S

2000-11-01

106

Electrokinetic properties of polymer colloids  

NASA Technical Reports Server (NTRS)

The surface of polymer colloids, especially polystyrene latexes, were modified for the purpose of controlling the electrokinetic properties of the resulting colloids. Achievement required a knowledge of electrical double layer charging mechanism, as a function of the electrolyte conditions, at the polymer/water interface. The experimental approach is to control the recipe formulation in the emulsion polymerization process so as to systematically vary the strong acid group concentration on the surface of the polymer particles. The electrophoretic mobility of these model particles will then be measured as a function of surface group concentration and as a function of electrolyte concentration and type. An effort was also made to evaluate the electrophoretic mobility of polystyrene latexes made in space and to compare the results with latexes made on the ground.

Micale, F. J.; Fuenmayor, D. Y.

1986-01-01

107

Incorporation of Landau-Pomeranchuk-Migdal effect and dielectric suppression effect in EGS5 code  

NASA Astrophysics Data System (ADS)

We incorporated the Landau-Pomeranchuk-Migdal (LPM) effect and the dielectric suppression effect for bremsstrahlung and the LPM effect for pair production in the EGS5 code. To verify the validity of the EGS5 code with the LPM plus dielectric cross section for bremsstrahlung, we compared the bremsstrahlung spectrum calculated using this code with that obtained considering the LPM effect. The values calculated using the EGS5 code reproduced the experimental value of the LPM effect well.

Kirihara, Y.; Namito, Y.; Hirayama, H.

2010-08-01

108

ELECTROKINETICS  

PubMed Central

1. The question of the critical pore diameter for streaming potential is discussed. 2. The surface charge is calculated for cellulose in contact with solutions of K3PO4, K2CO3, K2SO4, KCl, and ThCl4. 3. The surface charge of cellulose in contact with a solution of 2 x 10–4 N NaCl is calculated as a function of temperature and is found to show a sharp break at 39°. This is interpreted in terms of the change of the specific heat of water. 4. A marked ion antagonism is found in NaCl:KCl, KCl:MgCl2, NaCl:MgCl2, NaCl:CaCl2, KCl:CaCl2, CaCl2:MgCl2 mixtures when the surface charge is calculated as a function of concentration.

Moyer, Laurence S.; Bull, Henry B.

1935-01-01

109

Electrokinetic Focusing and Separation of Mammalian Cells in Conductive Biological Fluids  

PubMed Central

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 human breast adenocarcinoma spiked in urine, buffy coats, and processed blood samples with 98% capture efficiency.

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

2014-01-01

110

Electrokinetic particle translocation through a nanopore.  

PubMed

Nanoparticle electrophoretic translocation through a single nanopore induces a detectable change in the ionic current, which enables the nanopore-based sensing for various bio-analytical applications. In this study, a transient continuum-based model is developed for the first time to investigate the electrokinetic particle translocation through a nanopore by solving the Nernst-Planck equations for the ionic concentrations, the Poisson equation for the electric potential and the Navier-Stokes equations for the flow field using an arbitrary Lagrangian-Eulerian (ALE) method. When the applied electric field is relatively low, a current blockade is expected. In addition, the particle could be trapped at the entrance of the nanopore when the electrical double layer (EDL) adjacent to the charged particle is relatively thick. When the electric field imposed is relatively high, the particle can always pass through the nanopore by electrophoresis. However, a current enhancement is predicted if the EDL of the particle is relatively thick. The obtained numerical results qualitatively agree with the existing experimental results. It is also found that the initial orientation of the particle could significantly affect the particle translocation and the ionic current through a nanopore. Furthermore, a relatively high electric field tends to align the particle with its longest axis parallel to the local electric field. However, the particle's initial lateral offset from the centerline of the nanopore acts as a minor effect. PMID:21229154

Ai, Ye; Qian, Shizhi

2011-03-01

111

Electrokinetic properties of barite nanoparticles suspensions in different electrolyte media  

Microsoft Academic Search

In this study, electrokinetic properties of barite nanoparticles have been investigated in water. A series of systematic zeta\\u000a potential measurements have been performed to determine the isoelectric point (iep) and potential-determining ions (pdi),\\u000a and the effect of mono-, di-, and trivalent anions sodium salts such as NaCl, NaNO3, NaCH3COO, Na2SO4, Na2CO3, and Na3PO4 on the zeta potential of barite nanoparticles.

Jian Zhong Hang; Yu Fang Zhang; Li Yi Shi; Xin Feng

2007-01-01

112

Electrokinetic properties of sepiolite suspensions in different electrolyte media  

Microsoft Academic Search

The present paper deals with the electrokinetic characterization of sepiolite. A series of systematic zeta potential measurements have been carried out to determine the isoelectric point (iep) and potential-determining ions (pdi), and the effect of mono-, di-, and trivalent electrolytes such as NaCl, KCl, LiCl, NaNO3, NaCH3COO, MgCl2, CaCl2, BaCl2, CoCl2, CuCl2, Pb(NO3)2, Na2CO3, Na2SO4, AlCl3, FeCl3, and Na3PO4 on

Mahir Alkan; Özkan Demirba?; Mehmet Do?an

2005-01-01

113

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

114

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

115

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

116

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

117

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

118

Incorporating conservation zone effectiveness for protecting biodiversity in marine planning.  

PubMed

Establishing different types of conservation zones is becoming commonplace. However, spatial prioritization methods that can accommodate multiple zones are poorly understood in theory and application. It is typically assumed that management regulations across zones have differential levels of effectiveness ("zone effectiveness") for biodiversity protection, but the influence of zone effectiveness on achieving conservation targets has not yet been explored. Here, we consider the zone effectiveness of three zones: permanent closure, partial protection, and open, for planning for the protection of five different marine habitats in the Vatu-i-Ra Seascape, Fiji. We explore the impact of differential zone effectiveness on the location and costs of conservation priorities. We assume that permanent closure zones are fully effective at protecting all habitats, open zones do not contribute towards the conservation targets and partial protection zones lie between these two extremes. We use four different estimates for zone effectiveness and three different estimates for zone cost of the partial protection zone. To enhance the practical utility of the approach, we also explore how much of each traditional fishing ground can remain open for fishing while still achieving conservation targets. Our results show that all of the high priority areas for permanent closure zones would not be a high priority when the zone effectiveness of the partial protection zone is equal to that of permanent closure zones. When differential zone effectiveness and costs are considered, the resulting marine protected area network consequently increases in size, with more area allocated to permanent closure zones to meet conservation targets. By distributing the loss of fishing opportunity equitably among local communities, we find that 84-88% of each traditional fishing ground can be left open while still meeting conservation targets. Finally, we summarize the steps for developing marine zoning that accounts for zone effectiveness. PMID:24223870

Makino, Azusa; Klein, Carissa J; Beger, Maria; Jupiter, Stacy D; Possingham, Hugh P

2013-01-01

119

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

120

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

121

Fluid Mixing Control Inside a Y-shaped Microchannel by Using Electrokinetic Instability  

Microsoft Academic Search

A parametric study was conducted to improve our understanding pertaining to the fundamental physics of electrokinetic instability (EKI) and to explore the effectiveness of manipulating EKI waves to control\\/enhance fluid mixing inside a Y-shaped microchannel. The dependence of the critical strength of the applied static electric field to trigger the EKI waves on the conductivity ratio of the two mixing

Hui Hu; Zheyan Jin; Abdulilah Dawoud; Ryszard Jankowiak

2008-01-01

122

Nonlinear electrokinetic flow about a polarized conducting drop.  

PubMed

In the thin-double-layer limit ?a>1, electrokinetic flows about free surfaces are driven by a combination of an electro-osmotic slip and effective shear-stress jump. An intriguing case is that of a highly conducting liquid drop of radius a, where the inability to balance the viscous shear by Maxwell stresses results in an O(?a) velocity amplification relative to the familiar electro-osmotic scale. To illuminate the inherent nonlinearity we consider uncharged drops, where the induced surface-charge distribution results in a fore-aft symmetric electrokinetic flow profile with no attendant drop translation. This problem is analyzed using a macroscale model, where the double layer is represented by effective boundary conditions. Because of the intense flow, ionic convection within the O(1/?)-wide diffuse-charge layer is manifested by a moderate-zeta-potential surface-conduction effect. The drop deforms to a prolate shape in response to the combination of hydrodynamic forces and the effective electrocapillary reduction of the surface-tension coefficient, both mechanisms being asymptotically comparable. The flow field and the concomitant drop deformation are calculated using both a weak-field approximation and numerical simulations of the nonlinear macroscale model. PMID:23679365

Schnitzer, Ory; Yariv, Ehud

2013-04-01

123

Electrokinetic transport in natural soil cores  

Microsoft Academic Search

Electrokinetic transport in natural soils has been investigated by applying a constant voltage across 500mm long by approximately 200mm diameter natural soil cores for periods of up to 8 weeks. Contaminant ions were circulated through a fluid filled reservoir between the anode and the soil, and distilled water was circulated through a similar reservoir adjacent to the cathode. During the

Douglas I. Stewart; L. Jared West; S. Richard Johnston; Andrew M. Binley

1997-01-01

124

Electrokinetic migration studies on removal of chromium and uranyl ions from 904-A trench soil  

SciTech Connect

This report describes a laboratory-scale study, in which electrokinetic migration technology was used to remove chromium and uranium, as well as other ions, from soil taken from a bore hole adjacent to the 904-A trench at the Savannah River Technology Center. Imposition of an electric current on humid (not saturated) soil successfully caused cations to migrate through the pore water of the soil to the cathode, where they were captured in an ISOLOCKTm polymer matrix and in a cation exchange resin incorporated in the polymer. Chemicals circulated through the anode/polymer and cathode/polymer were able to control pH excursions in the electrokinetic-cells by reacting with the H[sup +] and OH[sup [minus

Bibler, J.P.; Meaker, T.F.; O'Steen, A.B.

1992-09-30

125

Pore network model of electrokinetic transport through charged porous media  

NASA Astrophysics Data System (ADS)

We introduce a method for the numerical determination of the steady-state response of complex charged porous media to pressure, salt concentration, and electric potential gradients. The macroscopic fluxes of solvent, salt, and charge are computed within the framework of the Pore Network Model (PNM), which describes the pore structure of the samples as networks of pores connected to each other by channels. The PNM approach is used to capture the couplings between solvent and ionic flows which arise from the charge of the solid surfaces. For the microscopic transport coefficients on the channel scale, we take a simple analytical form obtained previously by solving the Poisson-Nernst-Planck and Stokes equations in a cylindrical channel. These transport coefficients are upscaled for a given network by imposing conservation laws for each pores, in the presence of macroscopic gradients across the sample. The complex pore structure of the material is captured by the distribution of channel diameters. We investigate the combined effects of this complex geometry, the surface charge, and the salt concentration on the macroscopic transport coefficients. The upscaled numerical model preserves the Onsager relations between the latter, as expected. The calculated macroscopic coefficients behave qualitatively as their microscopic counterparts, except for the permeability and the electro-osmotic coupling coefficient when the electrokinetic effects are strong. Quantitatively, the electrokinetic couplings increase the difference between the macroscopic coefficients and the corresponding ones for a single channel of average diameter.

Obliger, Amaël; Jardat, Marie; Coelho, Daniel; Bekri, Samir; Rotenberg, Benjamin

2014-04-01

126

Pore network model of electrokinetic transport through charged porous media.  

PubMed

We introduce a method for the numerical determination of the steady-state response of complex charged porous media to pressure, salt concentration, and electric potential gradients. The macroscopic fluxes of solvent, salt, and charge are computed within the framework of the Pore Network Model (PNM), which describes the pore structure of the samples as networks of pores connected to each other by channels. The PNM approach is used to capture the couplings between solvent and ionic flows which arise from the charge of the solid surfaces. For the microscopic transport coefficients on the channel scale, we take a simple analytical form obtained previously by solving the Poisson-Nernst-Planck and Stokes equations in a cylindrical channel. These transport coefficients are upscaled for a given network by imposing conservation laws for each pores, in the presence of macroscopic gradients across the sample. The complex pore structure of the material is captured by the distribution of channel diameters. We investigate the combined effects of this complex geometry, the surface charge, and the salt concentration on the macroscopic transport coefficients. The upscaled numerical model preserves the Onsager relations between the latter, as expected. The calculated macroscopic coefficients behave qualitatively as their microscopic counterparts, except for the permeability and the electro-osmotic coupling coefficient when the electrokinetic effects are strong. Quantitatively, the electrokinetic couplings increase the difference between the macroscopic coefficients and the corresponding ones for a single channel of average diameter. PMID:24827338

Obliger, Amaël; Jardat, Marie; Coelho, Daniel; Bekri, Samir; Rotenberg, Benjamin

2014-04-01

127

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

128

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

PubMed

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 [see formula in text] in the fluctuation spectrum, which we relate to a nonlinear (E(2)) 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. PMID:19184149

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

2009-03-01

129

The Influence of Dielectric Decrement on Electrokinetics  

PubMed Central

We treat the dielectric decrement induced by excess ion polarization as a source of ion specificity and explore its impact on electrokinetics. We employ a modified Poisson-Nernst-Planck (PNP) equations accounting for the dielectric decrement. The dielectric decrement is determined by the excess ion polarization parameter ? and when ? = 0 the standard PNP model is recovered. Our model shows that ions saturate at large zeta potentials (?). Because of ion saturation, a condensed counterion layer forms adjacent to the charged surface, introducing a new length scale, the thickness of the condensed layer (lc). For the electro-osmotic mobility, the dielectric decrement weakens the electro-osmotic flow owing to the decrease of the dielectric permittivity. At large ?, when ? ? 0, the electro-osmotic mobility is found to be proportional to ?/2, in contrast to ? predicted by the standard PNP model. This is attributed to ion saturation at large ?. In terms of the electrophoretic mobility Me, we carry out both an asymptotic analysis in the thin-double-layer limit and solve the full modified PNP model to compute Me. Our analysis reveals that the impact of the dielectric decrement is intriguing. At small and moderate ?, the dielectric decrement decreases Me with an increasing ?. At large ?, it is well known that the surface conduction becomes significant and plays an important role in determining Me. It is observed that the dielectric decrement effectively reduces the surface conduction. Hence in stark contrast, Me increases as ? increases. Our predictions of the contrast dependence of the mobility on ? at different zeta potentials qualitatively agree with experimental results on the dependence of the mobility among ions and provide a possible explanation for such ion specificity. Finally, the comparisons between the thin-double-layer asymptotic analysis and the full simulations of the modified PNP model suggest that at large ? the validity of the thin-double-layer approximation is determined by lc rather than the traditional Debye length.

Zhao, Hui; Zhai, Shengjie

2013-01-01

130

Fundamental aspects of prolonged electrokinetic flows in kaolinites  

Microsoft Academic Search

Electrokinetic flows include the migration of fluid, chemicals, fine particles, bacteria, and electrons through a soil–fluid–chemical system driven by an externally applied direct-current (d.c.) electric field. The promising potential of electrokinetic remediation of contaminated fine-grained soils has stimulated recent interest in the study of electrokinetic flow processes, in particular the impact of a prolonged application of a d.c. electric field

A. T. Yeung

2006-01-01

131

Enhancement of In Vivo Anticancer Effect of Cisplatin by Incorporation Inside Carbon Nanohorns  

NASA Astrophysics Data System (ADS)

We have been studying potential applications of single-wall carbon nanohorns (SWNHs) to drug delivery systems. SWNHs are multiply functionalized with proteins, magnetites, tumor targeting molecules, and others. Various drugs are easily incorporated, and the incorporated drugs are slowly released. Almost no acute toxicity of SWNHs was found through various animal tests. We show in this report that anticancer effect of cisplatin was enhanced by incorporation inside SWNHs (CDDP@SWNH) as evidenced by in vivo tests: CDDP@SWNH was locally injected to tumors subcutaneously transplanted on mice. CDDP@SWNH inhibited the tumor growth more effectively than CDDP. This anticancer enhancement was achieved by large CDDP-quantity incorporated inside SWNH, slow release of CDDP from SWNH, long-term stay of SWNHs at the tumor sites, and an anticancer effect of SWNH itself [1].[3pt] [1] K. Ajima et al. ACSNano, 10(2008)2057-2064.

Yudasaka, Masako; Ajima, Kumiko; Murakami, Tatsuya; Mizoguchi, Yoshikazu; Tsuchida, Kunihiro; Ichihashi, Toshinari; Iijima, Sumio

2009-03-01

132

Nonlinear Electroosmosis and Biomolecule Electrokinetic Trapping Induced by Ion Selective Nanofluidic Channels  

NASA Astrophysics Data System (ADS)

This paper describes a nanofluidic device that can concentrate dilute biomolecule by electrokinetic trapping mechanism. This device has nanofluidic channels with a depth down to 40 nm, therefore, having significant Debye layer overlap. Depending on the strength of the applied potential across the nanochannel, one can observe phenomena such as concentration polarization; charge depletion and nonlinear electrokinetic flow in the adjacent microfluidic channel using fluorescent microscopy. By manipulating the electric field, the device can generate an extended space charge region, maintained for several hours, within a microchannel as a mean to collect and trap biomolecules. Our studies demonstrate such device can achieve up to 10 million fold sample preconcentration within 30 minutes. Besides, if applied a higher potential, a much faster chaotic flow can be seen in the microchannel adjacent to nanochannels. This kind of nonlinear electrokinetic flow is often called the electroosmosis of the second kind or induced-charge electroosmosis in electrode and ion exchange membrane studies. The presented device can be used as either a preconcentrator or an injector to other separation and detection systems preferred its performance and integrabilty. Also, it is an ideal experimental platform for studying such nonlinear electrokinetic effects, by directly tracking molecules in situ.

Wang, Ying-Chih; Han, Jongyoon

2006-03-01

133

Streaming potential observations, using geothermal wells and in situ electrokinetic coupling coefficients under high temperature  

NASA Astrophysics Data System (ADS)

In an attempt to detect streaming potentials induced by subsurface water flows, we have observed the horizontal electric field (self-potential) variations across stationary electric dipoles near geothermal wells in the Takinoue geothermal area, Japan. We observed variations of self-potential which seem to be associated with the water flows in the aquifer, induced by turning on and off the flow of the wells. Amplitudes of the variations are 3-5 mV across 60-200 m dipoles, and can be explained well with a proposed electrokinetic model: the streaming potential coefficient of - 15 mV/bar and/or the ?-potential of -50 to -100 mV in the aquifer are appropriate to explain the observed data by the model. The obtained electrokinetic coupling coefficients are in situ ones and determined for crustal rock-water system under high temperature (~200°C) condition. The present results, together with a laboratory study by Ishido and Mizutani (1981), give fundamental information on electrokinetic coupling coefficients in the earth's interior, and are very important when we make quantitative interpretations of self-potentials generated by geothermal activity on the basis of electrokinetic effects.

Ishido, Tsuneo; Mizutani, Hitoshi; Baba, Kenzo

1983-01-01

134

Hair analysis for drugs of abuse XIII. Effect of structural factors on incorporation of drugs into hair: the incorporation rates of amphetamine analogs  

Microsoft Academic Search

In order to clarify the incorporation mech-anism of drugs from blood into hair, seven effects of structural factors on the\\u000a incorporation rate (ICR) were studied using 32 amphetamine analogs: (1)?effect of a straight chained N-alkyl group; (2)?effect\\u000a of benzene and furan ring at N-position; (3)?effect of aliphatic and aromatic hydroxy groups; (4)?effect of triple bond group\\u000a at N-position; (5)?effect of

Yuji Nakahara; Ruri Kikura

1996-01-01

135

Improving electrokinetic microdevice stability by controlling electrolysis bubbles.  

PubMed

The voltage-operating window for many electrokinetic microdevices is limited by electrolysis gas bubbles that destabilize microfluidic system causing noise and irreproducible responses above ?3 V DC and less than ?1 kHz AC at 3 Vpp. Surfactant additives, SDS and Triton X-100, and an integrated semipermeable SnakeSkin® membrane were employed to control and assess electrolysis bubbles from platinum electrodes in a 180 by 70 ?m, 10 mm long microchannel. Stabilized current responses at 100 V DC were observed with surfactant additives or SnakeSkin® barriers. Electrolysis bubble behaviors, visualized via video microscopy at the electrode surface and in the microchannels, were found to be influenced by surfactant function and SnakeSkin® barriers. Both SDS and Triton X-100 surfactants promoted smaller bubble diameters and faster bubble detachment from electrode surfaces via increasing gas solubility. In contrast, SnakeSkin® membranes enhanced natural convection and blocked bubbles from entering the microchannels and thus reduced current disturbances in the electric field. This data illustrated that electrode surface behaviors had substantially greater impacts on current stability than microbubbles within microchannels. Thus, physically blocking bubbles from microchannels is less effective than electrode functionalization approaches to stabilize electrokinetic microfluidic systems. PMID:24648277

Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

2014-07-01

136

Laboratory scale electrokinetic remediation and geophysical monitoring of metal-contaminated marine sediments  

NASA Astrophysics Data System (ADS)

Electrokinetic remediation is an emerging technology that can be used to remove contaminants from soils and sediments. This technique relies on the application of a low-intensity electric field to extract heavy metals, radionuclides and some organic compounds. When the electric field is applied three main transport processes occur in the porous medium: electromigration, electroosmosis and electrophoresis. Monitoring of electrokinetic processes in laboratory and field is usually conducted by means of point measurements and by collecting samples from discrete locations. Geophysical methods can be very effective in obtaining high spatial and temporal resolution mapping for an adequate control of the electrokinetic processes. This study investigates the suitability of electrokinetic remediation for extracting heavy metals from dredged marine sediments and the possibility of using geophysical methods to monitor the remediation process. Among the geophysical methods, the spectral induced polarization technique was selected because of its capability to provide valuable information about the physico-chemical characteristics of the porous medium. Electrokinetic remediation experiments in laboratory scale were made under different operating conditions, obtained by varying the strength of the applied electric field and the type of conditioning agent used at the electrode compartments in each experiment. Tap water, 0.1M citric acid and 0.1M ethylenediamine tetraacetic acid (EDTA) solutions were used respectively as processing fluids. Metal removal was relevant when EDTA was used as conditioning agent and the electric potential was increased, as these two factors promoted the electroosmotic flow which is considered to be the key transport mechanism. The removal efficiencies ranged from 9.5% to 27% depending on the contaminant concerned. These percentages are likely to be raised by a further increase of the applied electric field. Furthermore, spectral induced polarization measurements were performed on the sediments before and after the treatment in order to correlate the measured electrical parameters with the geochemical processes occurring during electrokinetic remediation. A linear relationship was found between chargeability and pH. This result opens the door to the use of spectral induced polarization method to monitor electrokinetic processes in the field.

Masi, Matteo; Pazzi, Veronica; Losito, Gabriella

2013-04-01

137

Short-term effects of cover crop incorporation on soil carbon pools and nitrogen availability  

Microsoft Academic Search

Winter cover crops are increasingly used to maintain water quality and\\u000a agoecosystem productivity. Cover crop incorporation influences transient\\u000a soil microbial dynamics and nutrient availability at an early growth\\u000a stage of subsequent crops. Short-term (less than or equal to 35 d)\\u000a effects of cover crop incorporation on soil C pools and N availability\\u000a were evaluated using sandy loam soils from organically

S Hu; NJ Grunwald; AHC vanBruggen; GR Gamble; LE Drinkwater; C Shennan; MW Demment

1997-01-01

138

In situ soil remediation using electrokinetics  

SciTech Connect

Electrokinetics is emerging as a promising technology for in situ soil remediation. This technique is especially attractive for Superfund sites and government operations which contain large volumes of contaminated soil. The approach uses an applied electric field to induce transport of both radioactive and hazardous waste ions in soil. The transport mechanisms include electroosmosis, electromigration, and electrophoresis. The feasibility of using electrokinetics to move radioactive {sup 137}Cs and {sup 60}Co at the Hanford Site in Richland, Washington, is discussed. A closed cell is used to provide in situ measurements of {sup 137}Cs and {sup 60}Co movement in Hanford soil. Preliminary results of ionic movement, along with the corresponding current response, are presented.

Buehler, M.F.; Surma, J.E.; Virden, J.W.

1994-11-01

139

Electrokinetic properties of the mammalian tectorial membrane  

PubMed Central

The tectorial membrane (TM) clearly plays a mechanical role in stimulating cochlear sensory receptors, but the presence of fixed charge in TM constituents suggests that electromechanical properties also may be important. Here, we measure the fixed charge density of the TM and show that this density of fixed charge is sufficient to affect mechanical properties and to generate electrokinetic motions. In particular, alternating currents applied to the middle and marginal zones of isolated TM segments evoke motions at audio frequencies (1–1,000 Hz). Electrically evoked motions are nanometer scaled (?5–900 nm), decrease with increasing stimulus frequency, and scale linearly over a broad range of electric field amplitudes (0.05–20 kV/m). These findings show that the mammalian TM is highly charged and suggest the importance of a unique TM electrokinetic mechanism.

Ghaffari, Roozbeh; Page, Scott L.; Farrahi, Shirin; Sellon, Jonathan B.; Freeman, Dennis M.

2013-01-01

140

A novel microfluidic driver via AC electrokinetics.  

PubMed

A novel ac electrokinetic microfluidic driver based on alternating current electro-osmosis flow induced by asymmetrically capacitance/chemistry-modulated microelectrode arrays has been successfully developed and demonstrated. Asymmetric capacitance modulation (ACM) is made of comb electrode arrays and parts of individual electrode surfaces are modulated/deposited with a SiO(2) dielectric layer. This proposed design can be utilized to shift the optimal operation frequency of maximum velocity to a higher frequency to minimize electrolytic bubble generation and enhance micropumping performance. The pumping velocity, described in this paper, is measured via the tracing of microbeads and is a function of applied potential, signal frequency, buffer concentration, and dielectric layer thickness. A maximum pumping velocity up to 290 microm s(-1) in 5 mM buffer solution with the applied potential of 10 Vpp is observed in our prototype device, and the estimated maximum flow rate is up to 26.1 microl h(-1). This is the first successful demonstration regarding bubble-free ac electrokinetic micropumping via such asymmetrically capacitance-modulated electrode arrays. Design, simulation, microfabrication, experimental result, and theoretical model are described in this paper to characterize and exhibit the performance of the proposed novel bubble-free ac electrokinetic microfluidic driver. PMID:18432342

Kuo, Ching-Te; Liu, Cheng-Hsien

2008-05-01

141

Electrokinetic and Thermodynamic Analysis of the Dyeing Process of Polyamide Fabric with Mordant Black 17.  

PubMed

An electrokinetic and thermodynamic analysis of the dyeing process of polyamide 6.6 (nylon 6.6) by the dye Palatine chrome black (PCB) is described in the present work. The electrokinetic study was performed by means of electrophoretic mobility measurements on bare and dyed fiber. The most significant result is the increase in electrokinetic potential, zeta, toward more negative values as the dye concentration in the dispersion medium is raised. Given the molecular structure of PCB, which contains a sulfonate group per molecule, it is feasible that such increase in |zeta| is due to the adsorption of the negatively charged, dissociated dye entities. The uptake of PCB by the fiber is experimentally determined at two temperatures: the strong increase in the amount of dye incorporated into the fiber as the initial concentration of PCB is larger, and also the fact that higher temperatures favor the dyeing process is an indication of the existence of strong interactions between both interfaces. From a different point of view, the efficient coverage of Nylon by PCB is also demonstrated by the changes experienced by the surface free energy of Nylon upon treatment with PCB. Copyright 2001 Academic Press. PMID:11350132

Espinosa-Jiménez, M.; Perea-Carpio, R.; Padilla-Weigand, R.; Ontiveros, A.

2001-06-01

142

Mutagenic Effect of Radionuclides Incorporated into DNA of Drosophila Melanogaster. Progress Report, 1975--1976.  

National Technical Information Service (NTIS)

Progress is reported on research in the following areas: determination of mutagenic effects of tritium incorporated into DNA using exp 32 P, exp 33 P, and exp 14 C; dosimetry studies using number of disintegrations per minute per sperm cell; effect of the...

W. R. Lee

1976-01-01

143

Field Implementation of Electrokinetic-ISCO Remediation  

NASA Astrophysics Data System (ADS)

Challenges remain in the remediation of low-permeability porous media (e.g. clays, silts) contaminated with dissolved and sorbed organic contaminants. Current remediation technologies, such as in-situ chemical oxidation (ISCO), are often ineffective and the treatment region is limited by very slow rates of groundwater flow (advection) or molecular diffusion. Several studies (e.g. Reynolds et al. 2008) have highlighted the potential at a laboratory scale for utilising electrokinetic transport, through the application of an electric field, to deliver a remediation compound (e.g. permanganate, persulfate) within heterogeneous and low-permeability sediments for ISCO (termed EK-ISCO) or other treatments. A numerical modelling approach is highly beneficial to optimise the efficacy of EK-ISCO remediation. A numerical model was developed that simulates groundwater flow and multi-species reactive transport under hydraulic and electric gradients (Wu et al. 2010). Coupled into the existing, previously verified reactive transport model PHT3D (Prommer, Barry and Zheng 2003), the model was verified against analytical and experimental studies. This study, through numerical modelling, investigated the feasibility of various factors, such as electrode configurations, applied voltage and oxidant loading, for EK-ISCO treatment at several field sites. Successful in situ oxidation is dependent upon the electrokinetic transport and dispersal of oxidant through the contaminated region, however this is limited by modelled conditions such as natural oxidant demand and contaminant phase. Electrode configurations investigated included one-dimensional or two-dimensional configurations, unidirectional, bidirectional or rotational operations, and position of oxidant injection. References Prommer, H, Barry, DA and Zheng, C 2003, 'MODFLOW/MT3DMS-Based Reactive Multicomponent Transport Modeling', Ground Water, vol. 41, no. 2, pp. 247-257. Reynolds, DA, Jones, EH, Gillen, M, Yusoff, I and Thomas, DG 2008, 'Electrokinetic migration of permanganate through low permeability porous media', Ground Water, vol. 46, no. 4, pp. 629-637. Wu, MZ, Reynolds, D, Prommer, H, Fourie, A, Thomas, D, Robertson, TJ and Hodges, D 2010, 'A Coupled Electrokinetic Transport and Geochemical Reaction Model', in Proceedings of The 9th Symposium on Electrokinetic Remediation (EREM 2010), ed. GCC Yang, National Sun-Yet Sen University, Kaohsiung, pp. 67-68.

Wu, M. Z.; Reynolds, D. A.; Fourie, A.; Thomas, D.; Prommer, H.

2010-12-01

144

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...

145

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

146

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

147

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

2013-07-01

148

Numerical Simulation of Conductivity Gradient-Induced Electrokinetic Flow Instabilities  

NASA Astrophysics Data System (ADS)

This research is focused on the electrokinetic flow instabilities observed in long, thin microchannels with conductivity gradients orthogonal to the streamwise direction and applied potential. This situation often occurs in field amplified sample stacking (FASS) and isoelectric focusing, where control of the instabilities is imperative. Alternatively, the inherently chaotic flow patterns can be leveraged to fabricate an efficient micromixer under specific conditions. These instabilities arise from fluid body forces generated by the action of applied electric fields on electrolyte concentration-based conductivity gradients. A model is developed to describe the phenomena in general and applied specifically to thin microchannels with the conductivity gradient perpendicular to the applied field (both DC and AC). A higher-order, depth averaged correlation is proposed to account for the out of plane effects. Numerical simulations performed using COMSOL 3.2 are compared to 2-D and 3-D simulations as well as experimental data for multiple geometries with good agreement.

Bradford, Stephen; Meinhart, Carl

2006-03-01

149

Induced-charge electrokinetic phenomena: theory and microfluidic applications.  

PubMed

We give a general, physical description of "induced-charge electro-osmosis" (ICEO), the nonlinear electrokinetic slip at a polarizable surface, in the context of some new techniques for microfluidic pumping and mixing. ICEO generalizes "ac electro-osmosis" at microelectrode arrays to various di-electric and conducting structures in weak dc or ac electric fields. The basic effect produces microvortices to enhance mixing in microfluidic devices, while various broken symmetries--controlled potential, irregular shape, nonuniform surface properties, and field gradients--can be exploited to produce streaming flows. Although we emphasize the qualitative picture of ICEO, we also briefly describe the mathematical theory (for thin double layers and weak fields) and apply it to a metal cylinder with a dielectric coating in a suddenly applied dc field. PMID:14995255

Bazant, Martin Z; Squires, Todd M

2004-02-13

150

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

151

Alcohol Treatment and Cognitive-Behavioral Therapy: Enhancing Effectiveness by Incorporating Spirituality and Religion  

ERIC Educational Resources Information Center

Cognitive-behavioral therapy (CBT) is an effective modality for the treatment of alcoholism. Given widespread interest in incorporating spirituality into professional treatment, this article orients practitioners to spiritually modified CBT, an approach that may enhance outcomes with some spiritually motivated clients. More specifically, by…

Hodge, David R.

2011-01-01

152

The effectiveness of incorporating a real-time oculometer system in a commercial flight training program  

NASA Technical Reports Server (NTRS)

The effectiveness on pilot and trainee performance and scanning behavior of incorporating a real time oculometer system in a commerical flight training program was assessed. Trainees received simulator training in pairs requiring the trainees to alternate the order of training within a session. The 'third day phenomenon' of performance decrement was investigated, including the role of order of training on performance.

Jones, D. H.; Coates, G. D.; Kirby, R. H.

1982-01-01

153

Incorporating external evidence in trial-based cost-effectiveness analyses: the use of resampling methods  

PubMed Central

Background Cost-effectiveness analyses (CEAs) that use patient-specific data from a randomized controlled trial (RCT) are popular, yet such CEAs are criticized because they neglect to incorporate evidence external to the trial. A popular method for quantifying uncertainty in a RCT-based CEA is the bootstrap. The objective of the present study was to further expand the bootstrap method of RCT-based CEA for the incorporation of external evidence. Methods We utilize the Bayesian interpretation of the bootstrap and derive the distribution for the cost and effectiveness outcomes after observing the current RCT data and the external evidence. We propose simple modifications of the bootstrap for sampling from such posterior distributions. Results In a proof-of-concept case study, we use data from a clinical trial and incorporate external evidence on the effect size of treatments to illustrate the method in action. Compared to the parametric models of evidence synthesis, the proposed approach requires fewer distributional assumptions, does not require explicit modeling of the relation between external evidence and outcomes of interest, and is generally easier to implement. A drawback of this approach is potential computational inefficiency compared to the parametric Bayesian methods. Conclusions The bootstrap method of RCT-based CEA can be extended to incorporate external evidence, while preserving its appealing features such as no requirement for parametric modeling of cost and effectiveness outcomes.

2014-01-01

154

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

1976-01-01

155

Effect of incorporated PVP/Ag nanoparticles on ZnPc/C60 organic solar cells.  

PubMed

Various sizes of PVP-capped Ag nanoparticles were incorporated in the PEDOT:PSS layer of ZnPc/C60-based small-molecule organic solar cells. The incorporated nanoparticles partially block the incident light, but this was offset by the scattering effect and consequent increase in path lengths through the active organic layers. As a result, the overall power conversion efficiency of the cell increased by approximately 15% when nanoparticles with an average diameter of 24 nm were used. PMID:23862493

Heo, Ilsu; Kim, Jinhyun; Yim, Sanggyu

2013-06-01

156

Electrokinetic properties of sepiolite suspensions in different electrolyte media.  

PubMed

The present paper deals with the electrokinetic characterization of sepiolite. A series of systematic zeta potential measurements have been carried out to determine the isoelectric point (iep) and potential-determining ions (pdi), and the effect of mono-, di-, and trivalent electrolytes such as NaCl, KCl, LiCl, NaNO(3), NaCH(3)COO, MgCl(2), CaCl(2), BaCl(2), CoCl(2), CuCl(2), Pb(NO(3))(2), Na(2)CO(3), Na(2)SO(4), AlCl(3), FeCl(3), and Na(3)PO(4) on the zeta potential of sepiolite. Zeta potential has been calculated with the aid of Smoluchowski's equation. Sepiolite yields an isoelectric point at pH 6.6. The zeta potential for the sepiolite has ranged from +23.3 mV at pH approximately 2 to -22.4 mV at pH approximately 8 at 20 +/- 2 degrees C in water. The valency of the ions have proven to have a great influence on the electrokinetic behavior of the suspension. Monovalent cations were found to have a weak effect, while di- and trivalent cations made the zeta potential positive. Charge reversal was observed for divalent cations at 1 x 10(-2) M and for trivalent cations at 3 x 10(-4) M. As a result, it can be said that monovalent cations are indifferent ions when di- and trivalent cations are potential-determining ions. PMID:15567402

Alkan, Mahir; Demirba?, Ozkan; Do?an, Mehmet

2005-01-01

157

Nanocapillary Membrane Devices: A Study in Electrokinetic Transport Phenomena  

NASA Astrophysics Data System (ADS)

There is considerable interest in developing micro-total analysis systems, also known as lab-on-a-chip devices, for applications in chemical and biological analysis. These devices often employ electrokinetic transport phenomena to move, mix, concentrate and separate dissolved species. The details of these phenomena in micro- and nanometer scale geometries are not fully understood; consequently, the basic principles of device operation are often unclear. For example, nanocapillary membranes (NCM) and other nanometer-sized passages can exhibit charge-selectivity and rectification effects similar to those observed in biological membranes. This dissertation addresses several issues related to ion transport in these membranes. Leading-order 1D steady-state models for diffusion-layer modulated transport through non-ideal membranes are used to study ionic rectification in geometrically asymmetric devices. These models provide qualitative explanations of the operation of a variety of fluidic rectifiers and experimentally observed hysteresis effects. By taking the first steps in the full boundary-layer analysis of the model, it is shown that non-ideal membranes do not maintain local electro-neutrality under passage of electric current. This is in contrast to the usual assumption of membrane local electro-neutrality, but is compatible with the existence of the non-equilibrium macroscopic space charge known to appear in the flanking electrolyte and the requirement of overall charge conservation. Lastly, the problem of electrokinetic instability due to non-equilibrium electro-osmotic slip is considered for the case of an electrolyte-membrane interface inside a 2D channel.

Schiffbauer, Jarrod

158

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

PubMed

A number of bench scale laboratory column tests were carried out using a newly designed and developed electrokinetic cell to investigate the fundamental behavior of zinc-spiked kaolin clay subjected to an electric field. Laboratory investigations focused on (i) zinc migration by the combined effects of electromigration and electro-osmosis and (ii) the electrically induced desorption characteristics of zinc-contaminated kaolin that occurred during processing. The correlations of the applied voltage gradient, electro-osmotic flow rate, and the development of a pH gradient were examined and evaluated. The results showed that the removal efficiency was high during the early stage of processing due to rapid desorption by electrokinetic effects in the cathode region. However, the majority of zinc migrating from the anode was precipitated due to the high pH environment in the cathode region. PMID:17530420

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

2007-08-01

159

DOES USE-OF-FORCE SIMULATION TRAINING IN CANADIAN POLICE AGENCIES INCORPORATE PRINCIPLES OF EFFECTIVE TRAINING?  

Microsoft Academic Search

Numerous police agencies in Canada incorporate use-of-force simulation training into their overall instructional regime. A prominent theory of learning, known as cognitive load theory, suggests that in order for this training to be effective, instructional methods must facilitate the acquisition and automation of task-relevant schemas without overwhelming the limited processing capacity of the learner. In this article, several instructional effects,

Craig Bennell; Natalie J. Jones; Shevaun Corey

2007-01-01

160

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

161

Application of sequential extraction analysis to electrokinetic remediation of cadmium, nickel and zinc from contaminated soils  

Microsoft Academic Search

An enhanced electrokinetic process for the removal of cadmium (Cd), nickel (Ni) and zinc (Zn) from contaminated soils was performed. The efficiency of the chelate agents nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA) and diaminocycloexanetetraacetic acid (DCyTA) was examined under constant potential gradient (1.23V\\/cm). The results showed that chelates were effective in desorbing metals at a high pH, with metal–chelate anion

Apostolos Giannis; Despina Pentari; Jing-Yuan Wang; Evangelos Gidarakos

2010-01-01

162

Electrokinetic microslit experiments to analyse the charge formation at solid\\/liquid interfaces  

Microsoft Academic Search

Electrokinetic effects play an important role in microfluidics and nanofluidics. Although the related phenomena are often utilized to control fluid flow and sample transport in lab-on-a-chip devices, their dependency on the surface charges on the channel walls often remain enigmatic. This is mainly due to the lack of adequate experimental methods to analyse the electrical charging of solid\\/liquid interfaces of

Ralf Zimmermann; Toshihisa Osaki; Rüdiger Schweiß; Carsten Werner

2006-01-01

163

Comparing the influence of electrode materials in electrokinetic experiments: Evidence from literature and laboratory measurements  

Microsoft Academic Search

In the laboratory, commonly two types of electrodes are used to measure electrokinetic effects like streaming potentials in clays and other earth materials. On the one hand, reversible Ag\\/AgCl electrodes are used, whereas in other studies, noble metal oxidation-reduction electrodes like platinum or gold are employed. This paper shortly outlines the different types of electrodes and their application in earlier

Katja Heister; Pieter J. Kleingeld; Gustav Loch

164

INFLUENCE OF SURFACTANT TYPES ON CORRELATION OF RETENTION FACTOR AND HYDROPHOBICITY OF SELECTED TRIAZOLE FUNGICIDES IN MICELLAR ELECTROKINETIC CHROMATOGRAPHY  

Microsoft Academic Search

Application of micellar electrokinetic chromatography (MEKC) in quantitative structure-retention relationship (QSRR) has been studied for selected triazole fungicides. Effect of different surfactant types and concentrations of bile salts and sodium dodecyl sulfate on the correlation between logarithm of retention factor (log k) in MEKC and logarithm of octanol-water partition coefficient (log P ow ) was investigated. Five standard fungicides (cyproconazole,

Wan Aini; Wan Ibrahim; Dadan Hermawan; Mohamed Noor Hasan; Mohd Marsin Sanagi

165

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

166

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

167

In Situ Electrokinetic Enhancement for Self-Assembled-Monolayer-Based Electrochemical Biosensing  

PubMed Central

This study reports a multifunctional electrode approach which directly implements electrokinetic enhancement on a self-assembled-monolayer-based electro-chemical sensor for point-of-care diagnostics. Using urinary tract infections as a model system, we demonstrate that electrokinetic enhancement, which involves in situ stirring and heating, can enhance the sensitivity of the strain specific 16S rRNA hybridization assay for 1 order of magnitude and accelerate the time-limiting incubation step with a 6-fold reduction in the incubation time. Since the same electrode platform is used for both electrochemical signal enhancement and electrochemical sensing, the multifunctional electrode approach provides a highly effective strategy toward fully integrated lab-on-a-chip systems for various biomedical applications.

Sin, Mandy L. Y.; Liu, Tingting; Pyne, Jeffrey D.; Gau, Vincent; Liao, Joseph C.; Kin Wong, Pak

2014-01-01

168

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

2012-11-15

169

Towards an understanding of induced-charge electrokinetics at large applied voltages in concentrated solutions.  

PubMed

The venerable theory of electrokinetic phenomena rests on the hypothesis of a dilute solution of point-like ions in quasi-equilibrium with a weakly charged surface, whose potential relative to the bulk is of order the thermal voltage (kT/e approximately 25 mV at room temperature). In nonlinear electrokinetic phenomena, such as AC or induced-charge electro-osmosis (ACEO, ICEO) and induced-charge electrophoresis (ICEP), several V approximately 100 kT/e are applied to polarizable surfaces in microscopic geometries, and the resulting electric fields and induced surface charges are large enough to violate the assumptions of the classical theory. In this article, we review the experimental and theoretical literatures, highlight discrepancies between theory and experiment, introduce possible modifications of the theory, and analyze their consequences. We argue that, in response to a large applied voltage, the "compact layer" and "shear plane" effectively advance into the liquid, due to the crowding of counterions. Using simple continuum models, we predict two general trends at large voltages: (i) ionic crowding against a blocking surface expands the diffuse double layer and thus decreases its differential capacitance, and (ii) a charge-induced viscosity increase near the surface reduces the electro-osmotic mobility; each trend is enhanced by dielectric saturation. The first effect is able to predict high-frequency flow reversal in ACEO pumps, while the second may explain the decay of ICEO flow with increasing salt concentration. Through several colloidal examples, such as ICEP of an uncharged metal sphere in an asymmetric electrolyte, we show that nonlinear electrokinetic phenomena are generally ion-specific. Similar theoretical issues arise in nanofluidics (due to confinement) and ionic liquids (due to the lack of solvent), so the paper concludes with a general framework of modified electrokinetic equations for finite-sized ions. PMID:19879552

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

2009-11-30

170

Ultraviolet irradiation effects incorporation of nitrate and nitrite nitrogen into aquatic natural organic matter  

USGS Publications Warehouse

One of the concerns regarding the safety and efficacy of ultraviolet radiation for treatment of drinking water and wastewater is the fate of nitrate, particularly its photolysis to nitrite. In this study, 15N NMR was used to establish for the first time that UV irradiation effects the incorporation of nitrate and nitrite nitrogen into aquatic natural organic matter (NOM). Irradiation of 15N-labeled nitrate in aqueous solution with an unfiltered medium pressure mercury lamp resulted in the incorporation of nitrogen into Suwannee River NOM (SRNOM) via nitrosation and other reactions over a range of pH from approximately 3.2 to 8.0, both in the presence and absence of bicarbonate, confirming photonitrosation of the NOM. The major forms of the incorporated label include nitrosophenol, oxime/nitro, pyridine, nitrile, and amide nitrogens. Natural organic matter also catalyzed the reduction of nitrate to ammonia on irradiation. The nitrosophenol and oxime/nitro nitrogens were found to be susceptible to photodegradation on further irradiation when nitrate was removed from the system. At pH 7.5, unfiltered irradiation resulted in the incorporation of 15N-labeled nitrite into SRNOM in the form of amide, nitrile, and pyridine nitrogen. In the presence of bicarbonate at pH 7.4, Pyrex filtered (cutoff below 290–300 nm) irradiation also effected incorporation of nitrite into SRNOM as amide nitrogen. We speculate that nitrosation of NOM from the UV irradiation of nitrate also leads to production of nitrogen gas and nitrous oxide, a process that may be termed photo-chemodenitrification. Irradiation of SRNOM alone resulted in transformation or loss of naturally abundant heterocyclic nitrogens.

Thorn, Kevin A.; Cox, Larry G.

2012-01-01

171

Numerical studies of electrokinetic control of DNA concentration in a closed-end microchannel.  

PubMed

A major challenge in lab-on-a-chip devices is how to concentrate sample molecules from a dilute solution, which is critical to the effectiveness and the detection limit of on-chip bio-chemical reactions. A numerical study of sample concentration control by electrokinetic microfluidic means in a closed-end microchannel is presented in this paper. The present method provides a simple and efficient way of concentration control by using electrokinetic trapping of a charged species of interest, controlling liquid flow and separating different sample molecules in the microchannel. The electrokinetic-concentration process and the controlled transport of the sample molecules are numerically studied. In this system, in addition to the electroosmotic flow and the electrophoresis, the closed-end of the chamber causes velocity variation at both ends of the channel and induces a pressure gradient and the associated fluid movement in the channel. The combined effects determine the final concentration field of the sample molecules. The influences of a number of parameters such as the channel dimensions, electrode size and the applied electric field are investigated. PMID:20191548

Daghighi, Yasaman; Li, Dongqing

2010-03-01

172

Oxygen incorporation effects in annealed epitaxial La(1-x)SrxMnO3 thin films  

NASA Astrophysics Data System (ADS)

This paper presents our results regarding oxygen incorporation effects in epitaxial La(1-x)SrxMnO3 thin films, deposited on SrTiO3 (001) single crystal substrates, by annealing in different gas mixtures of argon and oxygen. A particular emphasis is placed on the correlation of structural properties with the magnetic properties of the films, Curie temperature, and coercive field. In this sense, we demonstrate that the evolution of the diffuse part of the ?-scans performed on the films are due to oxygen excess in the film lattice, which creates cationic vacancies within the films. Also, we show that two regimes of oxygen incorporation in the films exist, one in which the films evolve toward a single phase and oxygen stoichiometry is recovered, and a second one dominated by oxygen over-doping effects. In order to support our study, XPS measurements were performed, from which we have evaluated the Mn3+/Mn4+ ionic ratio.

Petrisor, T.; Gabor, M. S.; Boulle, A.; Bellouard, C.; Tiusan, C.; Pana, O.; Petrisor, T.

2011-06-01

173

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

174

Effect of zoledronic acid on incorporation of a bioceramic bone graft substitute  

Microsoft Academic Search

Many osteoporotic fracture patients are candidates for concurrent treatment with bisphosphonates and bioceramic bone graft substitutes. Osteopromotive silica-based bioactive glasses are known to induce accelerated local bone turnover and adjunct antiresorptive agents, such as zoledronic acid, may affect the process. The current study examined the effect of adjunct zoledronic acid therapy on bioactive glass incorporation. In Harlan Sprague–Dawley rats (n = 80),

Ville-Valtteri Välimäki; Niko Moritz; Jessica J. Yrjans; Eero Vuorio; Hannu T. Aro

2006-01-01

175

TOPICAL REVIEW: Theory of electrostatics and electrokinetics of soft particles  

NASA Astrophysics Data System (ADS)

We investigate theoretically the electrostatics and electrokinetics of a soft particle, i.e. a hard particle covered with an ion-penetrable surface layer of polyelectrolytes. The electric properties of soft particles in an electrolyte solution, which differ from those of hard particles, are essentially determined by the Donnan potential in the surface layer. In particular, the Donnan potential plays an essential role in the electrostatics and electrokinetics of soft particles. Furthermore, the concept of zeta potential, which is important in the electrokinetics of hard particles, loses its physical meaning in the electrokinetics of soft particles. In this review, we discuss the potential distribution around a soft particle, the electrostatic interaction between two soft particles, and the motion of a soft particle in an electric field.

Ohshima, Hiroyuki

2009-12-01

176

Dual-asymmetry electrokinetic flow focusing for pre-concentration and analysis of catecholamines in CE electrochemical nanochannels.  

PubMed

In this research, a technique incorporating dual-asymmetry electrokinetic flow (DAEKF) was applied to a nanoCE electrochemical device for the pre-concentration and detection of catecholamines. The DAEKF was constructed by first generating a zeta-potential difference between the top and bottom walls, which had been pre-treated with O2 and H2O surface plasma, respectively, yielding a 2-D gradient shear flow across the channel depth. The shear flow was then exposed to a varying zeta-potential along the downstream direction by control of the field-effect in order to cause downward rotational flow in the channel. By this mechanism, almost all of the samples were effectively brought down to the electrode surface for analysis. Simulations were carried out to reveal the mechanism of concentration caused by the DAEKF, and the results reasonably describe our experiment findings. This DAEKF technique was applied to a glass/glass CE electrochemical nanochip for the analysis of catecholamines. The optimum detection limit was determined to be 1.25 and 3.3 nM of dopamine and catechol, respectively. A detection limit at the zeptomole level for dopamine can be obtained in this device, which is close to the level released by a single neuron cell in vitro. PMID:19639573

Wu, Ren-Guei; Yang, Chung-Shi; Lian, Cheng-Kuang; Cheing, Ching-Chang; Tseng, Fan-Gang

2009-07-01

177

Herbicidal effects of extracts and residue incorporation of Datura metel against parthenium weed.  

PubMed

The present study was designed to evaluate the herbicidal activity of Datura metel against the noxious weed parthenium (Parthenium hysterophorus L.). In a laboratory bioassay, the effect of aqueous, methanol and n-hexane shoot and root extracts of 5, 10, 15 and 20% w/v (on a fresh weight basis) concentration of D. metel were tested against the germination and seedling growth of parthenium. Both aqueous and methanol extracts markedly suppressed the germination and seedling growth of parthenium. Generally, the effect of shoot extracts was more pronounced than the effect of root extracts. In foliar spray bioassay, aqueous and methanol shoot extracts of 10% w/v (on dry weight bases) concentrations were sprayed on one-week and two-week-old pot-grown parthenium seedlings. Two subsequent sprays were carried out at five day intervals each. Both the aqueous as well as the methanol extracts significantly suppressed shoot length as well as shoot and root biomass of one-week and two-week-old parthenium plants. In residue incorporation bioassay, crushed shoots of D. metel were incorporated in the soil at 1, 2, ... 5% w/w. Parthenium seeds were sown one week after residue incorporation and plants were harvested 40 days after sowing. Incorporation of 2-5% residues significantly reduced germination by 47-89%. Residues of 4 and 5% concentration significantly suppressed plant biomass by 90 and 97%, respectively. The present study concludes that root and shoots of D. metel contain herbicidal constituents for the management of parthenium weed. PMID:20812130

Javaid, Arshad; Shafique, Sobiya; Shafique, Shazia

2010-09-01

178

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

179

Electrokinetic sample injection for high-sensitivity CZE (part 2): improving the quantitative repeatability and application of electrokinetic supercharging-CZE to the detection of atmospheric electrolytes.  

PubMed

Electrokinetic supercharging (EKS) is defined as a technique that combines electrokinetic sample injection with transient ITP. Quantitative repeatability of EKS-CZE and the other CE methods using electrokinetic sample injection process is usually inferior in comparison with the CE methods using hydrodynamic or hydrostatic injection. This is due to some effects, such as the temperature change and the convection of the sample solution in the reservoir, as well as the change of the distance between an electrode and a capillary end (D(ec)). In particular, we have found that the D(ec) change might most seriously affect the repeatability, especially when the electrode is a thin Pt wire that could be unintentionally bent during sampling. By using a Teflon spacer to fix D(ec) to 1.1 mm, the RSD of peak area (n=5) was decreased from 20 to 3.4% in EKS-CZE for several metal cations. This D(ec) dependence of the sample amount injected was supported by computer simulation using CFD-ACE+ software. The improved repeatability (down to 5.1% at n=5, averaged RSD for Co(2+), Li(+), Ni(2+), Zn(2+) and Pb(2+)) was also experimentally attained by increasing the D(ec) to ca. 20 mm, which was also effective to obtain high sensitivity. Since the temperature and the convection effects on the repeatability are comparatively small in a proper laboratory environment, these effects were estimated from the EKS-CZE experiments using conditions such as warming and agitating the sample solution during EKS process. Finally, EKS-CZE was applied to the detection of ions from atmospheric electrolytes in high-purity water exposed to ambient air for 2 h. The microgram per liter levels of anions (chloride, sulfate, nitrate, formate, acetate and lactate) and cations (ammonium, calcium, sodium and magnesium) could be detected using conventional UV detector. PMID:19862736

Xu, Zhongqi; Koshimidzu, Eiji; Hirokawa, Takeshi

2009-10-01

180

[Effect of incorporating corn residues into soil on nitrogen transformation in soil-plant ecosystem].  

PubMed

Appropriate field management of crop residues can help to enhance soil productivity and nutrient recycling, and to minimize greenhouse gas emission. In this paper, a 15N tracer pot experiment was installed to study the effect of incorporating corn stalk and stubble into black soil on the nitrogen transformation in soil-plant ecosystem. The results indicated that compared with single application of N fertilizer, incorporation of corn stalk and stubble could increase soil nitrogen content and enhance its availability, and increase soil microbial nitrogen content. It also promoted the transfer of nitrogen in corn into its kernel, so as to increase the nitrogen use efficiency. Simultaneously, it reduced the content of soil NO3(-)-N, and decreased the fertilizer nitrogen loss by 4.7-5.6%. PMID:15227995

Wang, Shuping; Zhou, Guangsheng; Jiang, Yan; Liu, Xiaoyi

2004-03-01

181

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

182

Method and apparatus for electrokinetic transport  

NASA Technical Reports Server (NTRS)

Controlled electrokinetic transport of constituents of liquid media can be achieved by connecting at least two volumes containing liquid media with at least one dielectric medium with opposing dielectric surfaces in direct contact with said liquid media, and establishing at least one conduit across said dielectric medium, with a conduit inner surface surrounding a conduit volume and at least a first opening and a second opening opposite to the first opening. The conduit is arranged to connect two volumes containing liquid media and includes a set of at least three electrodes positioned in proximity of the inner conduit surface. A power supply is arranged to deliver energy to the electrodes such that time-varying potentials inside the conduit volume are established, where the superposition of said potentials represents at least one controllable traveling potential well that can travel between the opposing conduit openings.

James, Patrick Ismail (Inventor); Stejic, George (Inventor)

2012-01-01

183

Electrokinetic measurements of thin Nafion films.  

PubMed

We perform an electrokinetic characterization of ~300 nm Nafion films deposited on glass slides over a relatively unexplored region of ionic strength and pH. Owing to the small pore size of the Nafion, we probe the Nafion-fluid interface with the streaming potential measurement, and we probe ionic transport through the entire thickness of the Nafion film with the conductivity measurements. By applying a transport model for each of these measurements, we show that the inferred fixed charge density and characteristic fluid resistance length is different in each case. Analyzing our results with data from the literature, we suggest that our result is consistent with a thin Nafion film that is both nonuniform and weakly hydrated. Our regimen of experimentation and analysis may be generalized to characterize other porous and charged layers. PMID:24479374

Barbati, Alexander C; Kirby, Brian J

2014-03-01

184

Electrokinetic coupling in hydraulic fracture propagation  

NASA Astrophysics Data System (ADS)

Electrokinetic coupling is the most popular mechanism proposed to explain observed electromagnetic signals associated with the hydraulic fracturing of rocks. Measurements in both controlled laboratory and in situ conditions show clear evidence of the phenomenon. However there have been no reports on the description of the source mechanism, its relationship to a propagating crack, nor the electromagnetic field distribution due to such a source advancing through an electrically conductive medium. In this work it is shown that a surface electric current density arising on the walls of a fluid driven propagating crack can explain the measurements of electric streaming potential recorded during hydraulic fracturing experiments. The properties of the streaming current source are studied at the microscopic scale in light of the electrokinetic coupling expected at the outermost grains of the crack's surface. Expressions are derived for the average macroscopic transport equations describing the coupled fluid, and electrical current flow, at the interface between a fluid continuum and a homogeneous porous medium, where a Darcy flow regime (porous medium) competes with a rather Poiseuille type (fracture channels). The properties of the electrokinetic boundary sources are analyzed in light of the average electrical current density arising on the interface, as the fluid electrolyte flows in both the porous media and the adjacent fluid continuum. It is found that two coupling coefficients are required to describe the streaming current density. Indeed the flow is driven by both, a tangential pressure gradient, as well as by forward momentum transfer across the permeable boundary. The coupling coefficients are obtained from the spatial average of the tangential stress exerted on the pore surfaces, and they are found to be position dependent, as the tangential stress transitions from that on the porous conduits, to that on the surface of the outer most grains. Furthermore each coefficient gives rise to both a volumetric current density, due to the flow along the pore conduits, as well as a surface current density, due to the flow along the outer most surface. The latter contribution is found to dominate, as the tangential stress scales with the macroscopic characteristic length of the system. From a macroscopic stand point a source space-time function is established for the average current density prescribed by the pressure profile expected at the walls of a crack, which propagates under mobile equilibrium, in the context of linear elasticity theory. Expressions for the electromagnetic fields due to such a source are derived for a crack propagating with a constant velocity, in a homogeneous isotropic conducting medium. It is found that the spatial and temporal behavior of the fields reasonably agree with measurements performed under controlled laboratory experiments. In situ measurements are only studied qualitatively. Nevertheless, despite the obvious fact that a homogeneous whole-space medium does not appropriately describe a realistic earth model, the magnitude of the fields and the temporal behavior of the signals can be well reproduced using typical parameters of a hydraulic fracturing procedure. Electrokinetic coupling has also been proposed in the context of earthquake precursory signals, due to dilatant crack growth at depth. Several ideas have been discussed in the literature in order to justify experimental measurements of electromagnetic field which presumably appear before the onset of an earthquake. The source mechanism described in the present report, occurring at depth ranges of earthquake slip zones, yields electromagnetic signal levels which are 3 orders of magnitude smaller than the noise floor of currently available commercial instrumentation. This suggests that observing this type of phenomenon as an earthquake precursor would then be very challenging.

Cuevas, Nestor Herman

185

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

2013-10-15

186

Implementation of Electrokinetic-ISCO Remediation  

NASA Astrophysics Data System (ADS)

Significant challenges remain in the remediation of low-permeability porous media (e.g. clays, silts) contaminated with dissolved and sorbed organic contaminants. Current remediation technologies, such as in-situ chemical oxidation (ISCO), are often ineffective and the treatment region is limited by very slow rates of groundwater flow (advection) or molecular diffusion. At the laboratory-scale several studies (e.g. Reynolds et al. 2008) have highlighted the potential for utilising electrokinetic transport, as induced by the application of an electric field, to deliver a remediation compound (e.g. permanganate, persulfate) within heterogeneous and low-permeability sediments for ISCO (termed EK-ISCO) or other treatments. Process-based numerical modelling of the coupled flow, transport and reaction processes can provide important insights into the prevailing controls and feedback mechanisms and therefore guide the optimisation of EK-ISCO remediation efficacy. In this study, a numerical model was developed that simulates groundwater flow and multi-species reactive transport under both hydraulic and electric gradients (Wu et al. 2010). Coupled into the existing, previously verified reactive transport model PHT3D (Prommer et al. 2003), the model was verified against analytical solutions and data from experimental studies. Using the newly developed model, the sensitivity of electrokinetic, hydraulic and engineering parameters as well as alternative configurations of the EK-ISCO treatment process were investigated. The duration and energy required for remediation was most dependent upon the applied voltage gradient and the natural oxidant demand and all investigated parameters affected the remediation process to some extent. Investigated variants of treatment configurations included several alternative locations for oxidant injection and a series of one-dimensional and two-dimensional electrode configurations.

Wu, M. Z.; Reynolds, D.; Fourie, A.; Prommer, H.; Thomas, D.

2011-12-01

187

Time course of and effect of dietary iron level on iron incorporation into erythrocytes by infants.  

PubMed

As a part of our effort to explore various aspects of ferrokinetics in infancy, the present study was designed to determine the timing of entry of an orally ingested iron isotope into circulating erythrocytes, and the effect of the level of dietary iron [0.3 mg/100 kcal (418.4 kJ) vs. 1.8 mg/100 kcal] after isotope administration on erythrocyte incorporation of the isotope. We administered the stable isotope, (58)Fe, orally to 56-d-old and 168-d-old infants. All infants were fed a low-iron formula (LF) before and until 5 h after isotope administration. Thereafter, half the infants were fed a formula high in iron (HF group) while the remaining infants continued to receive the LF (LF group) for an additional 28 d. The quantity of (58)Fe in circulating erythrocytes increased from 14 to 28 d after isotope administration was nearly constant from 28 through 84 d of age (plateau value) and decreased between 84 and 112 d. Erythrocyte incorporation of (58)Fe was greater by the 168-d-old infants than by the 56-d-old infants, presumably because of the lesser iron stores of the older infants. In the 56-d-old infants, erythrocyte incorporation of (58)Fe was greater by the LF than by the HF group, but this difference was not significant in the 168-d-old infants. Thus, at least in younger infants, the level of iron intake after administration of an iron isotope affects erythrocyte incorporation of the isotope. The fact that less isotope was present in erythrocytes 112 d than 84 d after administration indicates that the life span of erythrocytes of infants, even beyond the immediate newborn period, is less than the 120-d life span of erythrocytes in the adult. PMID:10702582

Fomon, S J; Serfass, R E; Nelson, S E; Rogers, R R; Frantz, J A

2000-03-01

188

Impact of incorporated Al on the TiN/HfO2 interface effective work function  

NASA Astrophysics Data System (ADS)

First principles calculations of the impact of Al incorporation on the effective work function of a TiN/HfO2 interface are presented. The undoped interface has a midgap effective work function. We find that Al in the metal and Al substituting for O in the dielectric make the effective work function more n-type. More importantly, Al substituting for Hf in the oxide near the interface-the energetically stable position for most growth conditions-increases the effective work function, making it more p-type. Furthermore, the shift of the work function increases with increasing the Al concentration at the interface. The calculated results are consistent with experimental data.

Xiong, Ka; Robertson, John; Pourtois, Geoffrey; Pétry, Jasmine; Müller, Markus

2008-10-01

189

[Effect of the incorporation of additives on the aging of corn starch gels and "arepas"].  

PubMed

This research was carried out to investigate the effect of the incorporation of various additives on the ageing of corn starch and arepas. Starches were extracted from the endosperm of degerminated corn by a wet milling process, and its retrogradation, with or without the incorporation of additives was evaluated using the Brabender amilograph and by measuring the viscosity changes of the starch gels through time, using a Brookfield viscometer model RVT. The most effective additives in retarding the rate of ageing of starch gels, were used in the arepas. Likewise, trained panelists were utilized to find the levels of the additives incorporated in the arepas, by running taste threshold tests for each one of the additives. Textural changes of the arepas--maintained at two different storage temperatures, 9 degrees and 23 degrees C--were evaluated using an Instron texturometer. Preliminary tests with the corn starch allowed to choose the following additives: distilled monoglicerides, guar gum and hydrogenated vegetable oil. The effect of 15 different combinations of these additives on the texture of arepas was then studied, and findings revealed that only three of them were able to totally revert the retrogradation process, and maintain the hardness and elasticity within the expected range of a fresh-made arepa, when this is reheated until reaching a maximum temperature of 49 degrees C. A 66% of the hardening of the arepas prepared without additives can be reverted with the reheating process, but only if the product has not suffered dehydration. When stored for 24 hours at room temperature, unpacked arepas have a surface moisture loss of 47%, and even if reheated, hardening becomes irreversible in 84.6% of them. PMID:3154298

Rivero de Padua, M; Verde, O; Lucena de Orellana, M; Arias, J

1988-12-01

190

Choline incorporation into phospholipids in brain areas from spontaneously hypertensive rats: effect of oxiracetam treatment.  

PubMed

It has been demonstrated that spontaneously hypertensive rats (SHR) develop severe hypertension and cerebrovascular lesions on drinking 1% NaCl from weaning. These animals present a learning and memory impairment as well as impairment of both energy metabolism and membrane phospholipid turnover. We tested both choline uptake into the cells and incorporation into choline phosphoglyceride (CPG) by incubating slices from hippocampus and cortex. After 5 min of incubation, a noticeable decrease in free labelled choline content inside the cells as well as its incorporation into phospho-choline (PC) and CPG were found in the brain of SHR, as compared to Wistar-Kyoto (WK) rats. This may indicate that in the SHRs with cerebrovascular lesions there is a reduction in choline uptake which in turn causes a decline in CPG biosynthesis through de novo pathway. Oxiracetam treatment is able to restore the labeled choline content in the cells from SH rats, as well as the incorporation of choline into its derivatives PC and CPG, to the levels found in the WK or more. Tests performed in the presence of such a high affinity choline uptake as hemicholinium (HC) confirmed the capacity of oxiracetam to stimulate choline uptake into the cells even if the results obtained up to now are not sufficient to hypothesize a direct effect of oxiracetam on acetylcholine metabolism. In conclusion, from the results obtained it would seem reasonable to hypothesize that the effects of the drug above mentioned on the cholinergic system may be secondary to its effect on choline phosphoglycerides biosynthesis. PMID:1807290

Nardella, C; Terracina, L; Brunetti, M; Avellini, L; De Medio, G E; Gaiti, A; Belfiore, P; Mariani, O

1991-09-01

191

Photoinduced piezooptic effect in the benzene molecular crystallites incorporated within the polyvinyl alcohol matrices  

NASA Astrophysics Data System (ADS)

Optically induced elasto (piezo-)-optics effect (EOE) in the benzene large-sized nanocrystallites with sizes 80-100 nm incorporated within the polyvinyl alcohol matrices was observed for the first time. A correlation between the number of macrovacancies measured by positron annihilation and the values of EOE coefficient indicates on appearance of enhanced static dipole moments caused by defects. Simultaneously changes of time kinetics of the EOE in picosecond time regime is observed. A substantial role of electron-phonon subsystem in the observed EOE is shown.

Ozga, K.

2004-02-01

192

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

PubMed

Traditional Indian unleavened bread (chapati) was prepared by incorporating wheat bran (insoluble fiber) and oat bran (soluble fiber) at different levels into whole wheat flour. Central composite rotatable design with 2 independent variables (wheat bran and oat bran) at 5 levels (wheat bran 3-9, oat bran 6-12%) was used to design the experiments. The flour samples containing different concentration of bran were analysed for pasting and mixing characteristics. Wheat bran had a negative (p ? 0.05) effect on peak viscosity, break down and final viscosity, whereas oat bran had a positive (p ? 0.05) effect on set back and final viscosity. Among mixing characteristics, the peak value was negatively affected (p ? 0.05) with increase in the level of both variables. Both variables had positive (p ? 0.05) effect on hardness of chapati while the cohesiveness, chewiness and overall acceptability scores were negatively affected. Based on compromise optimization, it is recommended to incorporate 5.5 g wheat bran and 9.7 g oat bran per 100 g flour for making optimally acceptable fiber rich chapati. PMID:23572620

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

2010-03-01

193

Dehalorespiration model that incorporates the self-inhibition and biomass inactivation effects of high tetrachloroethene concentrations.  

PubMed

In the vicinity of dense nonaqueous phase liquid (DNAPL) contaminant source zones, aqueous concentrations of tetrachloroethene (PCE) in groundwater may approach saturation levels. In this study, the ability of two PCE-respiring strains (Desulfuromonas michiganensis and Desulfitobacterium strain PCE1) to dechlorinate high concentrations of PCE was experimentally evaluated and depended on the initial biomass concentration. This suggests high PCE concentrations permanently inactivated a fraction of biomass, which, if sufficiently large, prevented dechlorination from proceeding. The toxic effects of PCE were incorporated into a model of dehalorespirer growth by adapting the transformation capacity concept previously applied to describe biomass inactivation by products of cometabolic TCE oxidation. The inactivation growth model was coupled to the Andrews substrate utilization model, which accounts for the self-inhibitory effects of PCE on dechlorination rates, and fit to the experimental data. The importance of incorporating biomass inactivation and self-inhibition effects when modeling reductive dechlorination of high PCE concentrations was demonstrated by comparing the goodness-of-fit of the Andrews biomass inactivation and three alternate models that do capture these factors. The new dehalorespiration model should improve our ability to predict contaminant removal in DNAPL source zones and determine the inoculum size needed to successfully implement bioaugmentation of DNAPL source zones. PMID:21182287

Huang, Deyang; Becker, Jennifer G

2011-02-01

194

Genomic prediction of hybrid performance in maize with models incorporating dominance and population specific marker effects.  

PubMed

Identifying high performing hybrids is an essential part of every maize breeding program. Genomic prediction of maize hybrid performance allows to identify promising hybrids, when they themselves or other hybrids produced from their parents were not tested in field trials. Using simulations, we investigated the effects of marker density (10, 1, 0.3 marker per mega base pair, Mbp(-1)), convergent or divergent parental populations, number of parents tested in other combinations (2, 1, 0), genetic model (including population-specific and/or dominance marker effects or not), and estimation method (GBLUP or BayesB) on the prediction accuracy. We based our simulations on marker genotypes of Central European flint and dent inbred lines from an ongoing maize breeding program. To simulate convergent or divergent parent populations, we generated phenotypes by assigning QTL to markers with similar or very different allele frequencies in both pools, respectively. Prediction accuracies increased with marker density and number of parents tested and were higher under divergent compared with convergent parental populations. Modeling marker effects as population-specific slightly improved prediction accuracy under lower marker densities (1 and 0.3 Mbp(-1)). This indicated that modeling marker effects as population-specific will be most beneficial under low linkage disequilibrium. Incorporating dominance effects improved prediction accuracies considerably for convergent parent populations, where dominance results in major contributions of SCA effects to the genetic variance among inter-population hybrids. While the general trends regarding the effects of the aforementioned influence factors on prediction accuracy were similar for GBLUP and BayesB, the latter method produced significantly higher accuracies for models incorporating dominance. PMID:22733443

Technow, Frank; Riedelsheimer, Christian; Schrag, Tobias A; Melchinger, Albrecht E

2012-10-01

195

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

196

Electrokinetic Remediation. II. Amphoteric Metals and Enhancement with a Weak Acid  

Microsoft Academic Search

A One-Dimensional Modl Is Developed For The Electrokinetic Treatment Of Aquifers Contaminated With An Ionic Salt. Electrokinetic Removal Of Amphoteric Metals Such As Zinc And Lead Is Simulated. The Use Of A Weak Acid (Acetic Acid) To Neutralize A Portion Of The Oh Generated Electrolytically In The Cathode Compartment Is Explored In Connection With The Electrokinetic Removal Of Nonamphoteric Metals

David J. Wilson; José Miguel Rodríguez-Maroto; César Gómez-Lahoz

1995-01-01

197

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

198

Determining the Effectiveness of Incorporating Geographic Information Into Vehicle Performance Algorithms  

SciTech Connect

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 vehicle performance algorithms. Sacramento and San Francisco were chosen because of the availability of high resolution (1/9 arc second) digital elevation data. First, I present a method for obtaining instantaneous road slope, given a latitude and longitude, and introduce its use into common driving intensity algorithms. I show that for trips characterized by >40m of net elevation change (from key on to key off), the use of instantaneous road slope significantly changes the results of driving intensity calculations. For trips exhibiting elevation loss, algorithms ignoring road slope overestimated driving intensity by as much as 211 Wh/mile, while for trips exhibiting elevation gain these algorithms underestimated driving intensity by as much as 333 Wh/mile. Second, I describe and test an algorithm that incorporates vehicle route type into computations of city and highway fuel economy. Route type was determined by intersecting trip GPS points with ESRI StreetMap road types and assigning each trip as either city or highway route type according to whichever road type comprised the largest distance traveled. The fuel economy results produced by the geographic classification were compared to the fuel economy results produced by algorithms that assign route type based on average speed or driving style. Most results were within 1 mile per gallon ({approx}3%) of one another; the largest difference was 1.4 miles per gallon for charge depleting highway trips. The methods for acquiring and using geographic data introduced in this thesis will enable other vehicle technology researchers to incorporate geographic data into their research problems.

Sera White

2012-04-01

199

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

200

Model for incorporating fuel swelling and clad shrinkage effects in diffusion theory calculations (LWBR Development Program)  

SciTech Connect

A model has been devised for incorporating into the thermal feedback procedure of the PDQ few-group diffusion theory computer program the explicit calculation of depletion and temperature dependent fuel-rod shrinkage and swelling at each mesh point. The model determines the effect on reactivity of the change in hydrogen concentration caused by the variation in coolant channel area as the rods contract and expand. The calculation of fuel temperature, and hence of Doppler-broadened cross sections, is improved by correcting the heat transfer coefficient of the fuel-clad gap for the effects of clad creep, fuel densification and swelling, and release of fission-product gases into the gap. An approximate calculation of clad stress is also included in the model.

Schick, W.C. Jr.; Milani, S.; Duncombe, E.

1980-03-01

201

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

NASA Astrophysics Data System (ADS)

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 AgNO3 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.

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

2007-09-01

202

Reionization on Large Scales. IV. Predictions for the 21 cm Signal Incorporating the Light Cone Effect  

NASA Astrophysics Data System (ADS)

We present predictions for the 21 cm brightness temperature power spectrum during the Epoch of Reionization (EoR). We discuss the implications of the "light cone" effect, which incorporates evolution of the neutral hydrogen fraction and 21 cm brightness temperature along the line of sight. Using a novel method calibrated against radiation-hydrodynamic simulations, we model the neutral hydrogen density field and 21 cm signal in large volumes (L = 2 Gpc h -1). The inclusion of the light cone effect leads to a relative decrease of about 50% in the 21 cm power spectrum on all scales. We also find that the effect is more prominent at the midpoint of reionization and later. The light cone effect can also introduce an anisotropy along the line of sight. By decomposing the 3D power spectrum into components perpendicular to and along the line of sight, we find that in our fiducial reionization model, there is no significant anisotropy. However, parallel modes can contribute up to 40% more power for shorter reionization scenarios. The scales on which the light cone effect is relevant are comparable to scales where one measures the baryon acoustic oscillation. We argue that due to its large comoving scale and introduction of anisotropy, the light cone effect is important when considering redshift space distortions and future application to the Alcock-Paczy?ski test for the determination of cosmological parameters.

La Plante, P.; Battaglia, N.; Natarajan, A.; Peterson, J. B.; Trac, H.; Cen, R.; Loeb, A.

2014-07-01

203

Comparison of microemulsion electrokinetic chromatography and micellar electrokinetic chromatography methods for the analysis of phenolic compounds.  

PubMed

In this study, microemulsion electrokinetic chromatography (MEEKC) and micellar electrokinetic chromatography (MEKC) were compared for their abilities to separate and detect thirteen phenolic compounds (syringic acid, p-coumaric acid, vanillic acid, caffeic acid, gallic acid, 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, (+)-catechin, (-)-epigallocatechin, (-)-epicatechin gallate, (-)-epigallocatechin gallate, (-)-epicatechin, and (-)-gallocatechin), and two other ingredients (caffeine and theophylline) in teas and grapes. Separation of phenolic compounds was improved by changing the SDS concentration for MEEKC, but the SDS concentration rarely affected the resolution for MEKC. Organic modifier (acetonitrile or methanol) was found to markedly influence the resolution and selectivity for both MEEKC and MEKC systems. In addition, a higher voltage and a higher column temperature improved the separation efficiency without any noticeable reduction in resolution for MEEKC whereas they caused a poor resolution for the MEKC system. Although separations with baseline resolution were achieved by the optimized MEEKC and MEKC methods, the separation selectivity resulting from the proposed MEEKC method was completely different from that of MEKC. PMID:16013824

Huang, Hsi-Ya; Lien, Wei-Chih; Chiu, Chen-Wen

2005-06-01

204

Microfluidic device for the electrokinetic manipulation of single molecules  

NASA Astrophysics Data System (ADS)

We are developing a microfluidic device for three-dimensional electrokinetic manipulation of single fluorescent molecules in solution. The device consists of electrode pairs deposited onto glass cover slips via UV microlithography and ionic sputtering. By positioning two such electrode pairs in a tetrahedral configuration separated by 100 microns and applying appropriate digitally-controlled voltages to each, the apparatus generates an electric field of selected directionality in the central bounded region. Proof of concept is demonstrated by controlling the motion of micron-size latex beads, visualized with an EM-CCD camera. By use of a double Mach-Zehnder interferometer configuration, 40 fs Ti:Sapphire laser pulses (repetition rate 76 MHz) are split into four temporally interleaved pulses (effective rate 304 MHz), which are then focused to the vertices of a tetrahedron (approximately one micron per side) within the central electrode region to generate two-photon-excited fluorescence from single molecules. The time stamp data from this four-focus probe, collected with a custom fast-timing single-photon avalanche diode, enables characterization of particle motion through fluorescence cross-correlation spectroscopy.

King, Jason; Davis, Lloyd; Canfield, Brian; Hofmeister, William; Sampson, Philip

2009-03-01

205

Self-consistent problem of induced polarization of electrokinetic origin  

NASA Astrophysics Data System (ADS)

In the first part of the paper, with some constraints, we find the analytical solution of the self-consistent problem of induced polarization (IP) for an electrokinetically polarized sphere. The stationary (on long time intervals) solution of the self-consistent problem is a set of the potential fields that are interconnected with each other: the exciting electric field, the extraneous hydrodynamical field (electroosmotic flow of a viscous incompressible fluid), and the resulting electromagnetic IP field. The extraneous field is the field of the osmotic flow of a charged liquid and the field of the charges that emerge due to the membrane effect in the narrowed segments of the pore channels. The calculations show that the IP fields derived by solving the self-consistent problem and by the Seigel-Komarov phenomenological approach are different. In the second part of the paper, by generalization of the obtained analytical solution, we formulate the self-consistent IP problem for isotropic ?-? media of arbitrary shape, which are bounded by a smooth surface. The problem can be solved by the numerical methods.

Svetov, B. S.; Ageev, V. V.; Karinskii, S. D.; Ageeva, O. A.

2013-11-01

206

Analyses of phenolic compounds by microemulsion electrokinetic chromatography.  

PubMed

In this study, a microemulsion electrokinetic chromatography (MEEKC) method was developed to analyze and detect 13 phenolic compounds (syringic acid, p-cumaric acid, vanillic acid, caffeic acid, gallic acid, 3,4-dihydroxybenzoic acid, 4-hydroxybenzoic acid, (+)-catechin, (-)-epigallocatechin, (-)-epicatechin gallate, (-)-epigallocatechin gallate, (-)-epicatechin, and (-)-gallocatechin), which are present in many plant-derived foods. The effects of cosurfactant, organic modifier, and oil were examined in order to optimize the separation of these phenolic compounds. The amounts of cosurfactant (cyclohexanol) and organic modifier (acetonitrile) were determined as the major influence on the separation selectivity, while the type of oil partially affected the separation resolution of the phenolic compounds. A highly efficient MEEKC separation method was achieved within 14 min by using a microemulsion solution of pH 2.0 containing 2.89% w/v SDS, 1.36% w/v heptane, 7.66% w/v cyclohexanol, and 2% w/v ACN. Furthermore, the present work could demonstrate that the nature of the oil phase has a significant influence on the separation selectivity of phenolic compounds. PMID:16041702

Huang, Hsi-Ya; Lien, Wei-Chih

2005-08-01

207

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

208

Imaging of Pressure- and Electrokinetically Driven Flows through Open Capillaries.  

PubMed

A new tool for imaging both scalar transport and velocity fields in liquid flows through microscale structures is described. The technique employs an ultraviolet laser pulse to write a pattern into the flow by uncaging a fluorescent dye. This is followed, at selected time delays, by flood illumination with a pulse of visible light which excites the uncaged dye. The resulting fluorescence image is collected onto a sensitive CCD camera. The instrument is designed as an oil immersion microscope to minimize beam steering effects. The caged fluorescent dye is seeded in trace quantities throughout the active fluid, thus images with high contrast and minimal distortion due to any molecular diffusion history can be obtained at any point within the microchannel by selectively activating the dye in the immediate region of interest. We report images of pressure- and electrokinetically driven steady flow within round cross section capillaries having micrometer scale inner diameters. We also demonstrate the ability to recover the velocity profile from a time sequence of these scalar images by direct inversion of the conserved scalar advection-convection equation. PMID:21644766

Paul, P H; Garguilo, M G; Rakestraw, D J

1998-07-01

209

Transport of radioactive ions in soil by electrokinetics  

SciTech Connect

An electrokinetic approach is being evaluated for in situ soil remediation at the Hanford Site in Richland, Washington. This approach uses an applied electric field to induce transport of both radioactive and hazardous waste ions in soil. The work discussed in this paper involves the development of a new method to monitor the movement of the radioactive ions within the soil during the electrokinetic process. A closed cell and a gamma counter were used to provide iii situ measurements of {sup 137}Cs and {sup 60}Co movement in Hanford soil. Preliminary results show that for an applied potential of 200 V over approximately 200 hr, {sup 137}Cs and {sup 60}60 were transported a distance of 4 to 5 in. The monitoring technique demonstrated the feasibility of using electrokinetics for soil separation applications.

Buehler, M.F.; Surma, J.E.; Virden, J.W.

1994-10-01

210

Method for eliminating gas blocking in electrokinetic pumping systems  

DOEpatents

A method for eliminating gas bubble blockage of current flow during operation of an electrokinetic pump. By making use of the ability to modify the surface charge on the porous dielectric medium used in electrokinetic pumps, it becomes possible to place electrodes away from the pressurized region of the electrokinetic pump. While gas is still generated at the electrodes they are situated such that the generated gas can escape into a larger buffer reservoir and not into the high pressure region of the pump where the gas bubbles can interrupt current flow. Various combinations of porous dielectric materials and ionic conductors can be used to create pumps that have desirable electrical, material handling, and flow attributes.

Arnold, Don W. (Livermore, CA) [Livermore, CA; Paul, Phillip H. (Livermore, CA) [Livermore, CA; Schoeniger, Joseph S. (Oakland, CA) [Oakland, CA

2001-09-11

211

Evaluation of electrode configuration and mode of DC power for improvement of electrokinetic soil remediation  

NASA Astrophysics Data System (ADS)

Electrokinetic soil remediation is also called electrokinetic soil processing, electroreclamation, and electrochemical decontamination. The electrokinetic technique needs a low-level direct current of the order of mA/cm2 between electrodes to remove contaminants. The electrokinetic technique is one of the most promising remediation processes, and offers high efficiency and time effectiveness in the decontamination of low-permeability soils contaminated with heavy metals, radionuclides, or organic compounds. The significance of this technique is attributed to its low operational cost and potential applicability to a wide range of contaminant types, and these benefits have resulted in the initiation of numerous studies into its use for waste remediation. Electrode configuration is crucial for cost-effectiveness and overall efficacy of the elelectrokinetic processing, particularly in its field implementation. We investigated the effectiveness of various electrode arrays which can be grouped into one-dimensional (1-D) and two-dimensional (2-D) ones. Normally, the DC electricity of full wave has been used to remove contaminants from soils using elelectrokinetic processing. However, application of half-wave DC power can be also taken into account to improve efficacy of the processing, because it generates pulse power and accelerates the migration of contaminants within soils. We empirically evaluated the effect of type of DC electricity on the overall performance of the electrokinetic soil processing. The 1-D configuration with 5 electrode pairs showed the least total electric power, but that consumed in only the soil cell was less in the 2-D arrays than in 1-D ones. Particularly, most of the electric power is likely to be consumed in the electrode compartments, and the electric resistance in the electrode parts should be reduced to save the electric energy cost in the whole processing. In terms of removal efficiencies of 5 heavy metal contaminants, overall efficiency was higher in the 2-D arrays than in the 1-D ones, and it is caused by the fact that the migration of heavy metals is enhanced towards cathode in the 2-D configuration because the current density increases in that direction due to nonlinear electric fields. Comparing removal efficiencies between Cu and Pb, the half-wave DC seems to be more effective in removing Pb, whereas Cu was more efficiently removed by the full-wave DC than by the half-wave DC power. This difference is likely to be caused by the two coupled reasons: difference in chemical fractionations of two heavy metals and difference in features between two kinds of DC electricity. The results suggest that the types of DC electric power as well as combination between them should be evaluated to improve overall efficacy and economy of whole electrokinetic processing for soil remediation.

Kim, Soon-Oh; Lee, Woo Chun; Lee, Sang Woo; Lee, Byung-Tae

2014-05-01

212

Release property and antioxidant effectiveness of tocopherol-incorporated LDPE/PP blend films.  

PubMed

Low-density polyethylene (LDPE)/polypropylene (PP) blend films in various blending ratios containing 3000?mg??kg?¹ of tocopherol were manufactured by an extrusion process. Tocopherol release properties were characterised and correlated with antioxidant effectiveness in retarding the oxidation of linoleic acid contacting the films at 40°C. The conditions without tocopherol (control) and with instant tocopherol addition corresponding to the amount included in the films were also prepared and compared with the film-contacting solutions. The effect of tocopherol inclusion and the blending ratio on their physical properties was also examined. A wide range of tocopherol diffusivity in 6.6?×?10?¹?-4.6?×?10?¹?m²?s?¹ were obtained by blend films. As PP content increases, the diffusivity decreased sharply at the beginning and levelled off later. The slower release of tocopherol in LDPE/PP blend films corresponding to lower tocopherol diffusivity retained the higher tocopherol concentration in the linoleic acid system providing better antioxidant effectiveness of the extended induction period in oxidation. The tocopherol inclusion reduced tensile strength and transparency significantly in an affordable range with higher tensile strength given by a higher PP ratio. LDPE/PP blending can be a useful tool to modulate the release profile of tocopherol and thus the antioxidant effectiveness of the tocopherol-incorporated antioxidant packaging film. PMID:22257167

Zhu, X; Lee, D S; Yam, K L

2012-01-01

213

Modeling Electrokinetic Flows by the Smoothed Profile Method  

PubMed Central

We propose an efficient modeling method for electrokinetic flows based on the Smoothed Profile Method (SPM) [1–4] and spectral element discretizations. The new method allows for arbitrary differences in the electrical conductivities between the charged surfaces and the the surrounding electrolyte solution. The electrokinetic forces are included into the flow equations so that the Poisson-Boltzmann and electric charge continuity equations are cast into forms suitable for SPM. The method is validated by benchmark problems of electroosmotic flow in straight channels and electrophoresis of charged cylinders. We also present simulation results of electrophoresis of charged microtubules, and show that the simulated electrophoretic mobility and anisotropy agree with the experimental values.

Luo, Xian; Beskok, Ali; Karniadakis, George Em

2010-01-01

214

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

215

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

216

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

217

Continuous flow microfluidic demixing of electrolytes by induced charge electrokinetics in structured electrode arrays.  

PubMed

A continuous flow microfluidic demixing process is realized. It utilizes high external electrical fields that are applied over electrically floating noble metal electrodes in an otherwise straight microchannel. The process converts axial electrical potential gradients into lateral molecular selective transport via a structure oriented ensemble of numerous electrodes. While the individual electrodes locally modify the electrolyte distribution by nonlinear electrokinetic effects and concentration polarization, the directed orientation of the electrode array combines the individual polarization zones to a dedicated molecular enrichment against the generated concentration gradient. A homogeneously concentrated electrolyte can be separated into arbitrarily shaped laminae of increased and depleted concentration by the presented microfluidic demixer. PMID:16503590

Leinweber, Felix C; Eijkel, Jan C T; Bomer, Johan G; van den Berg, Albert

2006-03-01

218

Effect of zoledronic acid on incorporation of a bioceramic bone graft substitute.  

PubMed

Many osteoporotic fracture patients are candidates for concurrent treatment with bisphosphonates and bioceramic bone graft substitutes. Osteopromotive silica-based bioactive glasses are known to induce accelerated local bone turnover and adjunct antiresorptive agents, such as zoledronic acid, may affect the process. The current study examined the effect of adjunct zoledronic acid therapy on bioactive glass incorporation. In Harlan Sprague-Dawley rats (n = 80), a standardized region of the proximal tibia was subjected to ablation of local bone marrow and filled with bioactive glass (BG) microspheres. Experimental animals received zoledronic acid (1.5 mug/kg, s.c., once a week, started 1 week before surgery) or doxycycline (a metalloproteinase inhibitor) (33 mg/kg, daily gavage) as a control agent. BG incorporation and geometric bone properties were followed by sequential pQCT imaging. The final outcome at 8 weeks was analyzed by digital radiography, histomorphometry, BEI-SEM, EDXA and muCT. The mRNA levels of markers for bone resorption (cathepsin K, TRACP, MMP-9, MMP-13) and synthesis (type I, II, III collagens, osteocalcin, osteonectin, osteopontin) were measured for determination of local bone turnover. Bones filled with BG microspheres produced 2.5-fold more intramedullary new bone than controls with bone marrow ablation only, but the BG filling delayed the recovery of pQCT strength strain index (SSI) of the bones. Adjunct therapy with zoledronic acid enhanced new bone formation on BG microspheres and particularly improved the SSI values of the BG-filled bones (P < 0.05). The zoledronic acid therapy alone (without BG filling) produced the highest amount of intramedullary new bone (6-fold more than in unfilled controls, P < 0.001) but did not show a similar benefit in SSI. The analyses of mRNA expression confirmed high local bone turnover in all bones with BG filling. At the 9th week of zoledronic acid treatment, bones with and without BG filling showed increased mRNA levels of bone resorption markers and decreased mRNA levels of markers for synthesis, indicating that a corrective resorption process was already in progress in response to massive accumulation of medullary new bone at earlier stages of the therapy. Adjunct antiresorptive therapy seems to be beneficial for incorporation of bioactive glass microspheres and does not block local natural remodeling processes. In the current model, the therapy even resulted in favorable remodeling of the tubular bone structure. PMID:16338190

Välimäki, Ville-Valtteri; Moritz, Niko; Yrjans, Jessica J; Vuorio, Eero; Aro, Hannu T

2006-03-01

219

Methods for incorporating effects of LWR coolant environment into ASME code fatigue evaluations.  

SciTech Connect

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Appendix I to Section HI of the Code specifies design fatigue curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Recent test data illustrate potentially significant effects of LWR environments on the fatigue resistance of carbon and low-alloy steels and austenitic stainless steels (SSs). Under certain loading and environmental conditions, fatigue lives of carbon and low-alloy steels can be a factor of {approx}70 lower in an LWR environment than in air. These results raise the issue of whether the design fatigue curves in Section III are appropriate for the intended purpose. This paper presents the two methods that have been proposed for incorporating the effects of LWR coolant environments into the ASME Code fatigue evaluations. The mechanisms of fatigue crack initiation in carbon and low-alloy steels and austenitic SSs in LWR environments are discussed.

Chopra, O. K.

1999-04-15

220

Automated Impedance-based Structural Health Monitoring Incorporating Effective Frequency Shift for Compensating Temperature Effects  

Microsoft Academic Search

This study presents an impedance-based structural health monitoring (SHM) technique considering temperature effects. The temperature variation results in significant impedance variations, particularly a frequency shift in the impedance, which may lead to erroneous diagnostic results of real structures, such as civil, mechanical, and aerospace structures. In order to minimize the effect of the temperature variation on the impedance measurements, a

Ki-Young Koo; Seunghee Park; Jong-Jae Lee; Chung-Bang Yun

2009-01-01

221

Effect of magnesium incorporation in zinc oxide films for optical waveguide applications  

NASA Astrophysics Data System (ADS)

Mg xZn 1-xO ( x=0.05-0.33) films were successfully deposited by the sol-gel spin coating method. Zinc acetate and magnesium acetate were used as starting precursors and ethanol as solvent to prepare the sol-gel. MgZnO films were deposited on silicon (1 0 0) substrate with varying molar composition and post annealed at 450 °C. Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometer (XRD), Ellipsometry, Scanning Electron Microscopy (SEM) and Energy Dispersive Analysis by X-ray (EDAX) was used to characterize the deposited films. Here, effect of Mg doping concentration on the chemical, structural, mechanical and optical properties of Mg xZn 1-xO films has been investigated. EDAX spectrum clearly shows the peak of Mg along with Zn and O indicating successful incorporation of Mg into the ZnO. From XRD spectra, it reveals that deposited film for 0.15 molar concentration was polycrystalline in nature. We succeeded in tailoring refractive index of MgZnO films from 1.44 to 1.11 corresponding to 0.05 to 0.33 Mg molar incorporation in ZnO. The refractive index was found to be decreased with an increase in Mg molar concentration and the stretching bond positions of fundamental ZnO peak was shifted from 409 to 417 cm -1. Our results explore the applicability of MgZnO as cladding layer material to form efficient heterostructure with ZnO as an active layer.

Sonawane, B. K.; Bhole, M. P.; Patil, D. S.

2010-03-01

222

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

223

Comparison of two electrokinetic methods – electroosmosis and streaming potential – to determine the zeta-potential of plane ceramic membranes  

Microsoft Academic Search

Electroosmotic flow rate and streaming potential measurements are used to characterise electrokinetic properties of plane ceramic membranes. The study is carried out at different pH, ionic strengths and electrolytes. Effects of pH and ionic strength are studied for both techniques which lead to very close values of isoelectric points. The specific adsorption of Ca2+ cations is observed with the two

A Szymczyk; P Fievet; M Mullet; J. C Reggiani; J Pagetti

1998-01-01

224

Optimization and validation of a micellar electrokinetic chromatographic method for the analysis of several angiotensin-II-receptor antagonists  

Microsoft Academic Search

We have optimized a micellar electrokinetic capillary chromatographic method for the separation of six angiotensin-II-receptor antagonists (ARA-IIs): candesartan, eprosartan mesylate, irbesartan, losartan potassium, telmisartan, and valsartan. A face-centred central composite design was applied to study the effect of the pH, the molarity of the running buffer, and the concentration of the micelle-forming agent on the separation properties. A combination of

S Hillaert; T. R. M De Beer; J. O De Beer; W Van den Bossche

2003-01-01

225

Spatial Distribution of Electrokinetically Driven Flow Measured by Micro-PIV (An Evaluation of Electric Double Layer in Microchannel)  

Microsoft Academic Search

The effect of varying pH on electrokinetically driven flow has been investigated by an optical measurement system using fluorescent submicron particles. The objectives of the present study are to establish quantitative measurements of electroosmotic velocity and zeta-potential, and to apply a spatially averaged time-resolved particle tracking velocimetry (SAT-PTV) technique to particle stacking affected by pH gradient. SAT-PTV can detect an

Mitsuhisa ICHIYANAGI; Koichiro SAIKI; Yohei SATO; Koichi HISHIDA

226

Incorporating translational research with clinical research to increase effectiveness in healthcare for better health  

PubMed Central

Background The transfer of new scientific discoveries into healthcare interventions requires that basic and clinical researchers work together with health care providers to generate team science. These innovative models require translational teams, and need to extend beyond the academic environment. The future of translational science requires partnerships with the healthcare community as well as the broader, general community. This new integrated model of effective translational teams holds promise for addressing thorny and persistent health disparities, is consistent with the nation’s strategic priority of eliminating health disparities, and bodes well for increasing healthcare effectiveness aimed at better health for all. Discussion As part of the 13th Research Centers in Minority Institutions (RCMI) International Symposium on Health Disparities, several senior academic leaders joined efforts to hold a workshop to discuss a model that considers the incorporation of two translational research strategies in research career development programs: Comparative effectiveness research (CER) and community-based participatory research (CBPR) for increasing healthcare effectiveness and eliminating healthcare disparities. Discussion included what issues may be most germane to the concept of a unified model for research workforce development through formal training and career development leading to increased effectiveness in healthcare for better health. Summary We believe that there is a gap in knowledge and skills in formal research career development programs that will enable physicians, other clinicians, and basic scientists to actively participate in these two translational research strategies. The purpose of this paper is to share the outcomes of these discussions, and encourage further discussion and possible innovation in the formulation of a new model for translational research workforce development.

2014-01-01

227

Incorporating the effects of increased atmospheric CO2 in watershed model projections of climate change impacts  

NASA Astrophysics Data System (ADS)

Simulation models such as the Hydrologic Simulation Program - FORTRAN (HSPF) and Soil-Water Assessment Tool (SWAT) are frequently used to project the responses of watershed processes to climate change, but do not always represent the effects of changes in atmospheric CO2 concentrations on plant growth. Projected increases in atmospheric CO2 concentrations may decrease the need for plants to maintain stomatal conductance to achieve sufficient CO2 inputs, thereby also reducing the transpiration of water with potentially important effects on watershed water balance. We first compare the SWAT model, which provides an option to explicitly represent the effects of increased CO2 to implementations of the SWAT model without this option and to the HSPF model, which does not include a representation of CO2 response. Both models are capable of representing watershed responses to current climatic conditions. For analysis of response to future conditions, the SWAT model with integrated plant growth response to increased CO2 predicts an increase in streamflows relative to models without the CO2 response, consistent with previous research. We then develop methods to incorporate CO2 impacts on evapotranspiration into a physically based modeling framework, such as HSPF, that does not explicitly model plant growth. With these modifications, HSPF also projects an increase in future runoff relative to simulations without accounting for the CO2 effect, although smaller than the increase predicted by SWAT with identical assumptions for stomatal conductance. The results suggest that, while the effect of reduced plant transpiration due to increased atmospheric CO2 is important, it is likely to be over-estimated by both the current formulation of the SWAT model and modified versions that reduce the stomatal conductance response for woody plants. A general approach to modifying watershed models to simulate response of plant transpiration to increased atmospheric CO2 under climate change is also proposed.

Butcher, Jonathan B.; Johnson, Thomas E.; Nover, Daniel; Sarkar, Saumya

2014-05-01

228

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

229

Economic impacts of noxious facilities: Incorporating the effects of risk aversion  

SciTech Connect

Developing new sites for noxious facilities has become a complex process with many potential pitfalls. In addition to the need to negotiate conditions acceptable to the host community, siting success may depend on the facility proposer`s ability to identify a candidate site that not only meets technical requirements, but that is located in a community or region whose population is not highly averse to the risks associated with the type of facility being proposed. Success may also depend on the proposer accurately assessing potential impacts of the facility and offering an equitable compensation package to the people affected by it. Facility impact assessments, as typically performed, include only the effects of changes in population, employment and economic activity associated with facility construction and operation. Because of their scope, such assessments usually show a short-run, net economic benefit for the host region, making the intensely negative public reaction to some types and locations of facilities seem unreasonable. The impact component excluded from these assessments is the long-run economic effect of public perceptions of facility risk and nuisance characteristics. Recent developments in psychological and economic measurement techniques have opened the possibility of correcting this flaw by incorporating public perceptions in projections of economic impacts from noxious facilities.

Nieves, L.A.

1993-09-01

230

[Separation of the effects of transmutation and radiation after incorporation of radionuclides into DNA (author's transl)].  

PubMed

Among the various methods for studying the relative effects of transmutation and radiation of incorporated nuclides, simulation of beta radiation by external gamma exposure is of practical importance. Self-irradiation and mutual irradiation of the labeled cells cannot be neglected in any case. Furthermore, additional hypothetical and experimental problems may arise from using either external beta radiation or different isotopes of an element. By means of external gamma irradiation on the other hand, this being equivalent to the internal beta radiation from a microdosimetrical point of view, the radiation effect of the nuclide alone can be observed without any modification of other experimental parameters. To determine such equivalent gamma radiation for labeled cell nuclei of Vicia faba roots, the authors applied the Monte Carlo Method to the beta spectra of 32-P, 3-H, 14-C and 131-J, to the energy-dependent LET and to different cell diameters. The existence of secondary particle equilibrium inside the nuclei during gamma exposure was assumed. For certain radionuclides and cell sizes it is possible to calculate gamma spectra which induce energy spectra in the nuclei similar to those caused by the beta particles originating in the nuclear DNA. PMID:1144670

Hamann, H J; Irskens, M

1975-01-01

231

Microemulsion and micellar electrokinetic chromatography of Hematoporphyrin D: a starting material of hematoporphyrin derivative.  

PubMed

An investigation of the basic factors which govern the microemulsion electrokinetic chromatography (MEEKC) and micellar electrokinetic chromatography (MEKC) separation of Hematoporphyrin D and its base hydrolysis product, hematoporphyrin derivative (HpD), was performed. These model compounds contain a complex mixture of porphyrin monomers, dimers and/or oligomers, and were utilized to gain insights into the MEEKC/micellar electrokinetic chromatography (MEKC) separation of samples containing highly lipophilic substances. For example, the organic modifier/cosurfactant (1-butanol) and/or oil phase (e.g., 1-octanol in comparison to ethyl acetate) were found to have an apparent influence on the separation selectivity of Hematoporphyrin D, the extent of which was dependent on the chemical nature of the surfactant employed (e.g., sodium dodecyl sulfate vs. sodium cholate). An interesting and important finding was that the presence of an organic modifier (methanol or acetonitrile at a concentration of 20% or higher) in the sample matrix as well as in the run buffer was essential for the optimal MEEKC or MEKC separation of a number of porphyrin monomers (including hematoporphyrin IX and its acetates, most likely hydroxyacetate, diacetate, and vinyl acetate, as well as its dehydration products, hydroxyethylvinyldeuteroporphyrin and protoporphyrin) contained in Hematoporphyrin D. On the other hand, the use of these optimized conditions for the MEEKC or MEKC separation of various oligomeric porphyrin species in HpD were unsatisfactory. As HpD is a well-known and effective photosensitizing agent in photodynamic therapy (a new approach for cancer treatment), the improved separation and characterization of various monomeric and oligomeric porphyrin species in HpD and its starting material, such as Hematoporphyrin D, is a challenging and important task. PMID:15669006

Li, Qi; Chang, C K; Huie, Carmen W

2005-02-01

232

Indirect laser-induced fluorescence detection of explosive compounds using capillary electrochromatography and micellar electrokinetic chromatography.  

PubMed

Mixtures of nitroaromatic and nitramine explosive compounds and their degradation products were analyzed using electrokinetically driven separations with both indirect laser-induced fluorescence (IDLIF) and UV absorption detection. Complete separations of the 14-component mixture (EPA 8330) were achieved using both capillary electrochromatography (CEC) and micellar electrokinetic chromatography (MEKC). IDLIF detection was performed using an epifluorescence system with excitation provided by a 635 nm diode laser and micromolar concentrations of the dye Cy-5 as the visualizing agent. While the sensitivity of the two detection methods was similar for the nitroaromatic compounds, the nitramines could only be detected using UV absorption due to their low fluorescence quenching efficiency of Cy-5. The detection sensitivity using IDLIF was limited by low frequency oscillations in the fluorescence background. The oscillations increased with higher electric field strength and were attributed to thermal fluctuations caused by Joule heating. Due to the more conductive running buffer and higher separation currents used in MEKC, sensitive IDLIF detection could only be achieved using low (approximately 100 V/cm) field strengths, resulting in long analysis times. CEC separations, which are typically run with low conductivity mobile phases to avoid bubble formation, are less sensitive to this effect. In CEC separations with IDLIF detection a stable fluorescence background using Cy-5 could be established using only a nonporous stationary phase. In capillaries packed with porous silica particles, anomalous migration behavior was observed with charged dye molecules and a stable fluorescence background could not be established under electrokinetic flow. This is the first demonstration of IDLIF in packed channel CEC. PMID:11001203

Bailey, C G; Wallenborg, S R

2000-09-01

233

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

PubMed

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. PMID:23113974

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

2012-11-21

234

Effects of toxic substances on natural bacterial assemblages determined by means of ( sup 3 H)thymidine incorporation  

SciTech Connect

The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were examined by means of ({sup 3}H)thymidine incorporation into trichloroacetic acid-insoluble material. Results from a large number of coastal marine and freshwater samples suggest the following. (i) The effects of the three toxicants included reductions in the bacterial cell number as well as changes in rates of ({sup 3}H)thymidine incorporation and in ({sup 3}H)thymidine incorporation per cell. The concentrations that inhibited ({sup 3}H)thymidine incorporation by 50% ranged from 3 to 11 mg liter{sup {minus}1} for 3,5-dichlorophenol, 5 to 10 mg liter{sup {minus}1} for 2,4-dinitrophenol, and 21 to 123 mg liter{sup {minus}1} for potassium dichromate, with a tendency to higher values in bacterial assemblages from more eutrophic environments. (ii) The effects of 3,5-dichlorophenol and potassium dichromate determined by ({sup 3}H) leucine incorporation into bacterial protein were similar or larger than those obtained from ({sup 3}H) thymidine incorporation. (III) Two to four hours of exposure to the toxicants was necessary before stable maximum effects were found in ({sup 3}H)thymidine incorporation. (IV) Storage of natural environmental samples should be avoided, since tests with water stored for 1 to 3 days sometimes produced results different from results obtained from in situ tests. (V) The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were relatively constant during periods with different growth rates in the assemblages, during various periods of the year, and between samples from freshwater and marine localities.

Riemann, B., Lindgaard-Jorgensen, P. (The Water Quality Institute, Horsholm (Denmark))

1990-01-01

235

The efficiency of electrokinetic pumping at a condition of maximum  

Microsoft Academic Search

Numerical methods are employed to examine the work, electric power input, and efficiency of electrokinetic pumps at a condition corresponding to maximum pump work. These analyses employ the full Poisson-Boltzmann equations and account for both convective and conductive electric currents, including surface conductance. We find that efficiencies at this condition of maximum work depend on three dimensionless parameters, the normalized

Stewart K. Griffiths; Robert H. Nilson

2004-01-01

236

Electrokinetic Property of Modified Polyacrylonitrile Membranes in the Haemodialysis  

Microsoft Academic Search

Experimental investigations of electrokinetic property of modified polyacrylonitrile membranes in the haemodialysis were performed using the streaming potential method. The zeta potentials of the membranes in the blood were estimated on the basis of Helmholtz-Smoluchowski equation. The experimental and calculation results show that the membranes are charged negatively, whose zeta potentials maintain at -20 mV around. And the aperture of

Lin Aiguo; Liu Peng

2009-01-01

237

Electrokinetic behavior and flotation of kaolinite in CTAB solution  

Microsoft Academic Search

The electrokinetics and flotation behavior of kaolinite in cetyltrimethylammonium bromide (CTAB) solution were studied. The point of zero charge (PZC) of kaolinite is 4.3. The possible mode of CTAB adsorption on kaolinite is due to Coulombic and Van der Waals forces revealed by zeta-potential and FTIR measurements. The negative zeta potential of kaolinite and the adsorption of cationic collectors on

Y Hu; H Jiang; D Wang

2003-01-01

238

Influence of Complex on Electrokinetic Remediation of Zinc Contaminated Soil  

Microsoft Academic Search

The efficiency of electrokinetic remediation of zinc contaminated soils and the influence of complex EDTA were researched by means of experiment for the complicated remediation of soil contaminated by typical heavy metal in this paper, and migration and variation characteristics of zinc were analyzed too. The experimental results indicated that the heavy metal pollutant could be enriched and removed in

Hu Hongtao

2010-01-01

239

Practical aspects of in-situ electrokinetic extraction  

Microsoft Academic Search

Electrokinetic extraction in an emerging technology that can be used to remove contaminants from heterogeneous fine-grained soils in situ. Contaminants in the subsurface are removed by the application of a direct-current electric field across the contaminated soil. The primary contaminant transport and removal mechanisms are electroosmotic advection and ionic migration. However, there are many complex physicochemical reactions occurring simultaneously during

Akram N. Alshawabkeh; Albert T. Yeung; Mark R. Bricka

1999-01-01

240

Electrokinetic extraction of heavy metals from dredged marine sediment  

Microsoft Academic Search

This study investigates the suitability of the electrokinetic process for extracting heavy metals from dredged marine sediment. Marine sediments have unique characteristics such as high alkalinity, high buffering capacity, and a large fraction of fine particles and organic contents. The target heavy metals were nickel (Ni), copper (Cu), zinc (Zn), and lead (Pb). Tap water was circulated in the anode

Kyung-Jo Kim; Do-Hyung Kim; Jong-Chan Yoo; Kitae Baek

2011-01-01

241

Numerical Simulation of Conductivity Gradient-Induced Electrokinetic Flow Instabilities  

Microsoft Academic Search

This research is focused on the electrokinetic flow instabilities observed in long, thin microchannels with conductivity gradients orthogonal to the streamwise direction and applied potential. This situation often occurs in field amplified sample stacking (FASS) and isoelectric focusing, where control of the instabilities is imperative. Alternatively, the inherently chaotic flow patterns can be leveraged to fabricate an efficient micromixer under

Stephen Bradford; Carl Meinhart

2006-01-01

242

MICELLAR ELECTROKINETIC CHROMATOGRAPHY-MASS SPECTROMETRY (R823292)  

EPA Science Inventory

The combination of micellar electrokinetic chromatography (MEKC) with mass spectrometry (MS) is very attractive for the direct identification of analyte molecules, for the possibility of selectivity enhancement, and for the structure confirmation and analysis in a MS-MS mode. The...

243

Electrokinetic demonstration at the unlined chromic acid pit.  

National Technical Information Service (NTIS)

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 e...

E. R. Lindgren M. G. Hankins E. D. Mattson P. M. Duda

1998-01-01

244

Influence of elevated temperature and pore fluid chemistry on electrokinetic signals generated during the deformation of sandstone  

NASA Astrophysics Data System (ADS)

Electrokinetic signals have been used at a crustal scale to infer fluid movement associated with rock deformation and in sub-surface reservoirs. While aspects of the electrokinetic phenomenon are well understood, the thermo-chemo-mechanical effects due to rock deformation under crustal conditions have been little explored. Here we present results from laboratory experiments where the combined influences of temperature, pore fluids and deformation strain rate on the generation of electrical potential signals are investigated. Sandstone samples were deformed in triaxial deformation with up to temperatures of 1250C using a range pore fluids with different chemistries, including deionised water and simulated reservoir formation waters (SFW's). We find that the most likely mechanism to generate electrical signals is the electrokinetic effect. The magnitude of the signals is influenced by temperature and pore fluid chemistry; however, the dependence on temperature requires sufficient time for thermal equilibrium to be reached to manifest itself. With the addition of ionic pore fluids, the magnitude of the electrical signals decreases with increasing temperature. Extrapolation shows that at temperatures above 2000C, no electrical potential signals would be observed. Projecting to a crustal scale, these results suggest that an earthquake at a depth of greater than 4 km with characteristic crustal fluids would not produce electrical signals distinguishable from background electrical noise.

Sammonds, P.; Eccles, D.; Meredith, P.

2012-04-01

245

Effect of flaxseed flour incorporation on the physical properties and consumer acceptability of cereal bars.  

PubMed

Extensive research has revealed numerous nutritional and health benefits of flaxseed due primarily to its nutrients content. The objective of this study was to evaluate the effect of flaxseed flour addition on the physical and sensory characteristics of cereal bars. Four formulations of the flaxseed cereal bars were prepared by partially replacing oats with flaxseed flour added at levels of 0 (control), 6%, 12% and 18%. There were no significant differences (p?>?0.05) in water activity, moisture and firmness values between the flaxseed bars and control. Flaxseed addition significantly (p??0.05) between the 12% flax cereal bars and the control with respect to sensory attributes and overall acceptability. The overall acceptability for both 12% flax bars and the control was in between 'like moderately' and 'like slightly' on the 9-point hedonic scale. The overall acceptability was most highly correlated with flavor acceptability for both control (r?=?0.80) and 12% flax (r?=?0.82) cereal bars. Flaxseed bars provided 12% dietary fiber of the daily recommended value. These results indicated that flaxseed flour incorporation up to 12% substantially enhanced the nutritional qualities of the cereal bars without affecting their sensory and quality properties. PMID:23733813

Khouryieh, H; Aramouni, F

2013-12-01

246

Effects of bFGF incorporated into a gelatin sheet on wound healing.  

PubMed

Basic fibroblast growth factor (bFGF) is well known to promote the proliferation of almost all cells associated with wound healing. However, as the activation duration of bFGF is very short in vivo, we incorporated bFGF into an acidic gelatin hydrogel and studied the sustained release of bFGF in vivo. In addition, we investigated the effects of the acidic gelatin sheet containing bFGF on wound healing. To distinguish wound contraction from neoepithelialization, we measured both the wound area and neoepithelium length. Other histological parameters such as thickness of granulation tissue and number of capillaries were also determined as indices of wound healing. Fibrous tissue was assessed using an Elastica van Gieson and Azan stain. A skin defect (1.5 x 1.5 cm) of full thickness was created on the back of each test mouse and the wound was covered with an acidic gelatin hydrogel, referred to as a gelatin sheet in this study (2 x 2 cm), with bFGF (100 microg/site) (A) or without bFGF (B). 1, 2, 3, 5, 7 and 14 days after covering, mice were killed and an enzyme-linked immunosorbent assay (ELISA) was performed to estimate the concentration of bFGF in the plasma. In another experiment, each wound was covered with (A), (B) or a hydrogel dressing (control group, C) and the wound area was measured 1 or 2 weeks postoperatively with a computer planimeter. The histological parameters, as mentioned above, were assessed using a light microscope. Sustained release of bFGF from the gelatin sheet was observed and the gelatin sheet containing bFGF promoted neoepithelialization, granulation, neovascularization and wound closure. This gelatin sheet containing bFGF was concluded to be effective for wound healing and promising for clinical use. PMID:16128295

Miyoshi, Michiyo; Kawazoe, Takeshi; Igawa, Hiroharu H; Tabata, Yasuhiko; Ikada, Yoshito; Suzuki, Shigehiko

2005-01-01

247

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

248

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

2013-01-01

249

Effects of Bi Incorporation on Cu(In1-x,Gax)Se2 Thin Films and Solar Cells  

NASA Astrophysics Data System (ADS)

The effects of bismuth (Bi) incorporation into Cu(In1-x,Gax)Se2 (CIGS) thin films and solar cells have been investigated. 10--50-nm-thick Bi thin layers were deposited onto Mo-coated soda-lime glass (SLG) and SiOx-coated SLG substrates by vacuum evaporation. CIGS thin films were then deposited by a three-stage process at substrate temperatures of 450--550 °C. The grain growth of CIGS thin films was enhanced, and the open-circuit voltage and hence the conversion efficiency was improved by the Bi incorporation when the SLG substrates were used. However, little effect was observed when the alkali barrier SiOx layer was deposited on SLG substrates. As a result, we found that the Bi incorporation is beneficial for improving the cell performance when sodium exists simultaneously in CIGS layers.

Nakakoba, Hiroya; Yatsushiro, Yuta; Mise, Takahiro; Kobayashi, Taizo; Nakada, Tokio

2012-10-01

250

The Incorporation of Effect Size in The Incorporation of Effect Size in Information Technology, Learning, Information Technology, Learning, and Performance Research and Performance Research  

Microsoft Academic Search

Research manuscripts published in the Information Technology, Learning, and Performance Journal are expected to adhere to the publication guidelines of the American Psychological Association (2001) and generally accepted research and statistical methodology. This manuscript describes the rationale supporting the reporting of effect size in quantitative research and also provides examples of how to calculate effect size for some of the

Joe W. Kotrlik; Heather A. Williams

251

Analysis of Governing Parameters for Silver-Silver Chloride Electrodes in Microfluidic Electrokinetic Devices  

Microsoft Academic Search

Electrokinetics has become a popular method of both particulate and fluidic control in microdevices. In an effort to address the problems associated with conventional electrokinetic control, we use silver-silver chloride electrodes for low-voltage, spatially localized electrokinetic control in microfluidic devices. This work presents an analysis of the electric fields generated by silver-silver chloride electrodes and establishes a nondimensional design parameter

Katherine A. Dunphy; Rohit N. Karnik; Christine Trinkle; Arun Majumdar

2005-01-01

252

Electrokinetic remediation. II. Amphoteric metals and enhancement with a weak acid  

SciTech Connect

A one-dimensional model is developed for the electrokinetic treatment of aquifers contaminated with an ionic salt. Electrokinetic removal of amphoteric metals such as zinc and lead is simulated. The use of a weak acid (acetic acid) to neutralize a portion of the OH{sup {minus}} generated electrolytically in the cathode compartment is explored in connection with the electrokinetic removal of nonamphoteric metals such as copper and cadmium.

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

1995-09-01

253

Effect of fO2 on the incorporation and diffusivity of Li in olivine  

NASA Astrophysics Data System (ADS)

Over the last decade the geochemical behaviour of Li has become of special interest since it was speculated that Li stable isotopes could be a promising tracer for subduction zone processes. However, there have been many studies of natural samples but our experimental and theoretical basis for interpreting these data is still lacking. Two diffusion mechanisms were identified for Li in olivine [1]. Their contribution to the net flux of Li in olivine depends on the vacancy concentration on the metal sites, which is sensitive to the fO2. Therefore we have studied the effect of fO2 on Li solubility and diffusion in olivine. Experimental approach: thin plates of crushed, natural olivine single crystals were embedded into two different kind of powders, ground plagioclase with about 2.5 ppm Li or a pre-annealed powder mixture of San Carlos olivine and isotopically enriched Li. All runs were performed in a gas-mixing furnace with fO2 controlled by flowing CO/CO2 mixture. In each run we simultaneously annealed about 100 micrometer-sized samples of Pakistan olivine and San Carlos olivine. In addition we have added to each run a mm sized crystallographically oriented parallelepiped of San Carlos olivine. For each powder reservoir we have performed a set of three anneals at 1200 C and different fO2. Cross sections of the run products were polished and analyzed with LA-ICP-MS. Results: In all cases the Li isotopes and concentrations were homogeneous in the 100 micrometer sized grains with one exception, the experiment at 1.e-10 bar with the highly enriched Li reservoir. The final Li concentration was slightly lower in the Pakistan than San Carlos olivine and was much lower in general if buffered by the plagioclase powder. Most importantly, the Li concentration increased systematically with increasing oxygen fugacity, indicating that the incorporation of Li in olivine is fO2 dependent. The mm-sized, oriented crystal was in most cases zoned and the extent of zoning depends on the diffusion direction. In addition the profiles became systematically longer with decreasing fugacity and at the most reducing conditions the crystal was almost homogenous. However, the isotopes were in all cases completely homogenized and equilibrated with the isotopically enriched reservoir. Thermodynamic model: We extended the quantitative point defect model for olivine [2] and reproduced the effect of fO2 on the solubility of Li when we assume it is mainly on the metal site and charge balanced by the formation of Fe3+ on the metal site. Conclusions: Our results strongly indicate that incorporation of Li is dependent on the fO2, less dependent on the trace element content. Diffusion of Li in olivine is anisotropic and dependent on fO2. Our quantitative point defect model for olivine underpins the experimental results. This will allow us to develop a multi-component diffusion model considering relevant point defects, e.g. Fe3+ and metal vacancies. Such a model will hopefully help us to simulate diffusion of Li at various natural circumstances including fO2 as a critical parameter. References: [1] Dohmen et al. (2010) Geochim Cosmochim Acta 74, 274-292; [2] Dohmen and Chakraborty (2007), Phys Chem Minerals 34, 597- 598.

Dohmen, R.; Coogan, L. A.

2012-12-01

254

Effect of silicate modulus and metakaolin incorporation on the carbonation of alkali silicate-activated slags  

SciTech Connect

Accelerated carbonation is induced in pastes and mortars produced from alkali silicate-activated granulated blast furnace slag (GBFS)-metakaolin (MK) blends, by exposure to CO{sub 2}-rich gas atmospheres. Uncarbonated specimens show compressive strengths of up to 63 MPa after 28 days of curing when GBFS is used as the sole binder, and this decreases by 40-50% upon complete carbonation. The final strength of carbonated samples is largely independent of the extent of metakaolin incorporation up to 20%. Increasing the metakaolin content of the binder leads to a reduction in mechanical strength, more rapid carbonation, and an increase in capillary sorptivity. A higher susceptibility to carbonation is identified when activation is carried out with a lower solution modulus (SiO{sub 2}/Na{sub 2}O ratio) in metakaolin-free samples, but this trend is reversed when metakaolin is added due to the formation of secondary aluminosilicate phases. High-energy synchrotron X-ray diffractometry of uncarbonated paste samples shows that the main reaction products in alkali-activated GBFS/MK blends are C-S-H gels, and aluminosilicates with a zeolitic (gismondine) structure. The main crystalline carbonation products are calcite in all samples and trona only in samples containing no metakaolin, with carbonation taking place in the C-S-H gels of all samples, and involving the free Na{sup +} present in the pore solution of the metakaolin-free samples. Samples containing metakaolin do not appear to have the same availability of Na{sup +} for carbonation, indicating that this is more effectively bound in the presence of a secondary aluminosilicate gel phase. It is clear that claims of exceptional carbonation resistance in alkali-activated binders are not universally true, but by developing a fuller mechanistic understanding of this process, it will certainly be possible to improve performance in this area.

Bernal, Susan A., E-mail: susana.bernal@gmail.co [Materials Engineering Department, Composite Materials Group, CENM, Universidad del Valle, Cali (Colombia); Mejia de Gutierrez, Ruby [Materials Engineering Department, Composite Materials Group, CENM, Universidad del Valle, Cali (Colombia); Provis, John L., E-mail: jprovis@unimelb.edu.a [Department of Chemical and Biomolecular Engineering, University of Melbourne, Victoria 3010 (Australia); Rose, Volker [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2010-06-15

255

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

256

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

PubMed Central

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.

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

2009-01-01

257

Single cell antimicrobial susceptibility testing by confined microchannels and electrokinetic loading  

PubMed Central

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 one hour compared to days in standard culture-based AST techniques.

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

2014-01-01

258

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

2013-04-16

259

On the behavior of electrokinetic streaming potential during protein filtration with fully and partially retentive nanopores.  

PubMed

An experimental investigation of the electrokinetic streaming potentials of both fully and partially retentive nanopores as compared with the filtration progress of dilute globular protein solution under different surface charge conditions was performed using hollow fibers. The streaming potential is generated by the electrokinetic flow effect within the electric double layer of the charged surface. Depending on the solution pH, both the protein and the pore wall can be either repulsive or attractive due to the long-range electrostatic interaction. The repulsive electrostatic interaction allows the protein particles to stay in a suspended state above the outer surface of hollow fibers instead of being deposited. The apparent streaming potential value at partially retentive pores is larger than that at fully retentive pores for the oppositely charged case; however, the opposite behavior is shown for the same-charged case. The axial-position-dependent streaming potential was also observed in order to explore the development of a concentration polarization layer during the cross-flow filtration. The time evolution of the streaming potential during the filtration of protein particles is related to the filtrate flux, from which it can be found to provide useful real-time information on particle deposition onto the outer surfaces of hollow fibers. PMID:12885535

Sung, Jun Hee; Chun, Myung-Suk; Choi, Hyoung Jin

2003-08-01

260

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

261

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

262

Simultaneous incorporation of carbonate and fluoride in synthetic apatites: Effect on crystallographic and physico-chemical properties  

Microsoft Academic Search

The mineral in bone is an impure hydroxyapatite, with carbonate as the chief minor substituent. Fluoride has been shown to stimulate osteoblastic activity and inhibit osteoclastic resorption in vitro. CO3- and F-substituted apatite (CFA) has been considered as potential bone graft material for orthopedic and dental applications. The objective of this study was to determine the effects of simultaneously incorporated

Fang Yao; John P LeGeros; Racquel Z LeGeros

2009-01-01

263

Effect of filler incorporation route on the properties of polysulfone–silver nanocomposite membranes of different porosities  

Microsoft Academic Search

Flat sheet porous polysulfone–silver nanocomposite membranes were synthesized by the wet phase inversion process. The effects of casting mixture composition and nanoparticle incorporation route on the morphological and separation properties of prepared membranes were studied by comparing nanocomposites of different preparations with silver-free controls. Silver nanoparticles were either synthesized ex situ and then added to the casting solution as an

Julian S. Taurozzi; Hari Arul; Volodymyr Z. Bosak; Anatoliy F. Burban; Thomas C. Voice; Merlin L. Bruening; Volodymyr V. Tarabara

2008-01-01

264

Development of a comprehensive free radical photopolymerization model incorporating heat and mass transfer effects in thick films  

Microsoft Academic Search

A comprehensive kinetic model describing photopolymerization is developed which allows variation of temperature, species concentrations, and light intensity through the thickness of a photopolymerized film. Heat and mass transfer effects are included, as is the generation of heat by both reaction and light absorption. In addition to initiation, propagation, and termination mechanisms, both primary radical termination and inhibition are incorporated

Michael D. Goodner; Christopher N. Bowman

2002-01-01

265

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

266

The Effect of Incorporation of HNO(sub 3) Into Liquid Sulfuric Acid on Heterogeneous Reaction Probabilities  

NASA Technical Reports Server (NTRS)

Using a fast-flow reactor coupled to a quadrupole mass spectrometer, the heterogeneous reactions of C1ONO2 + HCl and HOCl + HCl as well as hydrolysis of N2O5 and C1ONO2 were investigated on liquid sulfuric acid, with particular emphasis on the effect of incorporation of HNO3 on the reaction probabilities.

Zhang, R.; Leu, M-T.; Keyser, L.

1994-01-01

267

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

268

Blood cultures incorporating antibiotic absorbing resins as an index of effective chemotherapy  

Microsoft Academic Search

During a mean time of eight days, blood cultures made in duplicate with and without resins from nine patients with septicemia were evaluated. Data supporting the usefulness of blood cultures incorporating antibiotic absorbing resins as an index of chemotherapy are presented and discussed. The authors propose that this resin system be used not only to increase the sensitivity of blood

Domenico Colombrita; Giuseppe Ravizzola; Franco Pirali; Giovanna Meloni; Filomena Minelli; Nicoló Narbone; Adolfo Turano

1985-01-01

269

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

270

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

271

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

272

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

273

Numerical simulation of electrokinetic potentials associated with subsurface fluid flow  

SciTech Connect

A postprocessor has been developed to calculate space/time distributions of electrokinetic potentials resulting from histories of underground conditions (pressure, temperature, flowrate, etc.) computed by multi-phase multicomponent unsteady multidimensional geothermal reservoir simulations. Electrokinetic coupling coefficients are computed by the postprocessor using formulations based on experimental work reported by Ishido and Mzutani (1981). The purpose of the present study is to examine whether or not self-potential anomalies actually observed in real geothermal fields are consistent with quantitative mathematical reservoir models constructed using conventional reservoir engineering data. The most practical application of the postprocessor appears to be modeling self-potential changes induced by field-wide geothermal fluid production. Repeat self-potential surveying appears to be promising as a geophysical monitoring technique to provide constraints on mathematical reservoir models, in a similar fashion to the use of repeat microgravity surveys.

Ishido, Tsuneo; Pritchett, John W.

1996-01-24

274

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

275

Nuclear decontamination of cementitious materials by electrokinetics: An experimental study  

SciTech Connect

The objective of this paper is to evaluate the efficiency of an electrokinetic method of radionuclide removal from a cement-based material. This work is a two-part process. In the first part, a sample of mortar was uniformly contaminated for use as a reference. In order to ensure a uniform contamination, the ingress of the radioelement (cesium) was controlled by an external electrical field. The second part of this work concerns the removal of cesium from the contaminated mortar samples. This second, decontamination, phase was driven by the same electrical field. No electroosmosis was detected. Both phases were characterized by analyses of cesium and calcium concentrations in cathodic and anodic solutions, and by measurements of cesium content in the samples at the end of each phase. In addition to the electrical current, pH, and conductivity were measured during the experiments. Finally, the efficiency of the electrokinetic method was described in terms of decontamination factor, leading to promising results.

Frizon, F. [Laboratoire Materiaux et Durabilite des Constructions, INSA-UPS, Complexe Scientifique de Rangueil, 135 Avenue de Rangueil, 31077 Toulouse (France); CEA Marcoule, DEN/VRH/DTCD/SPDE/L2ED, Bat 37, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Lorente, S. [Laboratoire Materiaux et Durabilite des Constructions, INSA-UPS, Complexe Scientifique de Rangueil, 135 Avenue de Rangueil, 31077 Toulouse (France)]. E-mail: lorente@insa-toulouse.fr; Auzuech, C. [Laboratoire Materiaux et Durabilite des Constructions, INSA-UPS, Complexe Scientifique de Rangueil, 135 Avenue de Rangueil, 31077 Toulouse (France); CEA Cadarache, DEN/DED/SEP/LETD, Bat 352, 13108 St Paul-lez-Durance Cedex (France)

2005-10-01

276

Memory Effects in MetalOxideSemiconductor Capacitors Incorporating Dispensed Highly Monodisperse One-Nanometer Silicon Nanoparticles  

Microsoft Academic Search

MOS capacitors incorporating ex-situ produced, colloidal, highly mono-disperse, spherical, 1 nm Si nanoparticles were fabricated and evaluated for potential use as charge storage elements in future non-volatile memory devices. The CV characteristics are well behaved and agree with similarly fabricated zero-nanoparticle control samples and with an ideal simulation. Unlike larger particle systems, the demonstrated memory effect exhibits effectively pure hole

O. M. Nayfeh; D. A. Antoniadis; K. Mantey; M. H. Nayfeh

2007-01-01

277

Separation of natural pyrethrum extracts using micellar electrokinetic chromatography  

Microsoft Academic Search

The separation of the six pyrethrin esters in a technical pyrethrum extract (Riedel-de-Haën, Cresent Chemical Co. Inc. Hauppauge, NY, USA) by micellar electrokinetic chromatography (MEKC) using both sodium dodecyl sulfate (SDS) and a polymerized surfactant as pseudo-stationary phases has been investigated and optimized. Parameters such as pH, SDS and polymerized sodium N-undecyl sulfate (poly-SUS) concentration, type and concentration of background

Charles W Henry III; Shahab A Shamsi; Isiah M Warner

1999-01-01

278

Liposome Electrokinetic Chromatography: An in vitro Approach for Predicting Ecotoxicity  

Microsoft Academic Search

Liposome electrokinetic chromatography (LEKC) is a powerful tool for the study of drug membrane interactions. An investigation\\u000a of the use of the retention in LEKC as an in vitro approach to predict the ecotoxicity is proposed. The ecotoxicity parameters\\u000a (LC50 in fish, daphnia and mysid shrimp, EC50 in green algae and daphnia, and values of chronic ecotoxicity in fish and

DeLing Xian; KeLong Huang; SuQin Liu; JingYi Xiao

2008-01-01

279

Numerical simulation of electrokinetic focusing in microfluidic chips  

Microsoft Academic Search

In this paper, we adopt the Nernst–Planck equation and the full Navier–Stokes equation in the modeling of electro-osmotic flow in microfluidic chips. A voltage control model is proposed, which achieves electrokinetic focusing in a pre-focused cross injection system and which allows the volume of the sample to be controlled. In addition to the traditional cross system, we also present a

J-Y Lin; L-M Fu; R-J Yang

2002-01-01

280

Evaluation of Electrokinetic Technique for Industrial Waste Decontamination  

Microsoft Academic Search

Several industrial activities produce large amounts of metal-polluted sludge, disposal of which could pose serious environmental and ecological problems because of the usual high content of mobile metals. In this work, an electrokinetic technique was used to reduce the high metal content of two industrial wastes: sludges from mining (SM) and from the iron-steel (SIS) industry. Initially, a physical-chemical characterization

M. Pazos; M. T. Alcántara; C. Cameselle; M. A. Sanromán

2009-01-01

281

Phytolith assaying using a micron-scale electrokinetic sorting ring  

Microsoft Academic Search

A particularly useful indicator of past vegetation are phytoliths, glassy products of plant metabolism which have distinctive\\u000a size and morphology based on the plant taxa which produced them; however, their analysis is a time-consuming task. Building\\u000a on investigations into mobilizing and sorting of synthetic polystyrene microspheres using a closed loop rectangular microelectromechanical\\u000a systems (MEMS) electrokinetic array, we investigate these devices’

Kevin G. Stanley; Elizabeth Cornelia Robertson; Rene d’Entremont; Ted Hubbard; Marek Kujath

282

Electrokinetically Pumped Liquid Propellant Microthrusters for Orbital Station Keeping  

Microsoft Academic Search

For most orbital maneuvers, small satellites in the sub-10 kg range require thrusters capable of spanning the micro-Newton to milli-Newton force range. At this scale, electrokinetic (EK) pumping offers precise metering of monergolic or hypergolic liquid propellants under purely electrical control at pressures and flow rates well-suited to microthruster applications. We have demonstrated direct and indirect EK pumping for delivery

Michael S. Bartsch; M. H. McCrink; R. W. Crocker; B. P. Mosier; K. A. Peterson; K. Wally; K. D. Patel

2007-01-01

283

Electrokinetic dewatering of Turkish glass sand plant tailings  

Microsoft Academic Search

In this study, the dewatering of glass sand plant tailings from Mersin, Turkey was investigated using an electrokinetic technique. The particle size (d80) of the solid waste material tested was less than 0.020mm and consisted mainly of silica, orthoclase, alumina, potassium and iron oxides. In current plant practice, Larox high-pressure filters are used to produce a filter cake containing 22–25%

O. Bayat; O. Kilic; B. Bayat; M. Anil; H. Akarsu; C. Poole

2006-01-01

284

Hydrodynamics and electrokinetics of spherical liposomes with coatings of terminally anchored poly(ethylene glycol): Numerically exact electrokinetics with self-consistent mean-field polymer  

NASA Astrophysics Data System (ADS)

A detailed theoretical model is presented to interpret electrokinetic experiments performed on colloids with uncharged polymer layers. The methodology removes many of the degrees of freedom that otherwise have to be accounted for by adopting multiple empirical fitting parameters. Furthermore, the level of detail provides a firm basis for future studies examining liposome surface chemistry and charge, surface-charge mobility, and the dynamics of adsorbed polymer on fluidlike membranes. The model predictions are compared with experimental measurements of the electrophoretic mobility of stealth liposomes with molecular weights of terminally anchored poly(ethylene glycol) (PEG) in the range 0.35-10kgmol-1 [J. A. Cohen and V. A. Khorosheva, Colloids Surf. A 195, 113 (2001)]. The experimental data are interpreted by drawing upon self-consistent mean-field calculations of the polymer segment density distributions and numerically exact solutions of the governing transport equations [R. J. Hill, D. A. Saville, and W. B. Russel, J. Colloid Interface Sci. 258, 56 (2003)]. The approach leads to excellent agreement between theory and experiment with one adjustable parameter—the hydrodynamic size (Stokes radius) as?0.175Å of the statistical PEG segments with (Kuhn) length l=7.1Å . The remarkably small Stokes radius is demonstrated to be consistent with other applications of the well-known Debye-Brinkman model and, consequently, this work reveals important limitations of the mean-field hydrodynamic model. Despite such limitations, the “full” electrokinetic model is robust in its predictive capacity. The molecular weights of the terminally anchored PEG span the range where the coatings undergo a transition from mushroomlike to brushlike conformations, and the hydrodynamic size and electrophoretic mobility of the liposomes are demonstrated to be sensitive to the PEG chain length and the effects of double-layer polarization.

Hill, Reghan J.

2004-11-01

285

Hydrodynamics and electrokinetics of spherical liposomes with coatings of terminally anchored poly(ethylene glycol): numerically exact electrokinetics with self-consistent mean-field polymer.  

PubMed

A detailed theoretical model is presented to interpret electrokinetic experiments performed on colloids with uncharged polymer layers. The methodology removes many of the degrees of freedom that otherwise have to be accounted for by adopting multiple empirical fitting parameters. Furthermore, the level of detail provides a firm basis for future studies examining liposome surface chemistry and charge, surface-charge mobility, and the dynamics of adsorbed polymer on fluidlike membranes. The model predictions are compared with experimental measurements of the electrophoretic mobility of stealth liposomes with molecular weights of terminally anchored poly(ethylene glycol) (PEG) in the range 0.35-10 kg mol(-1) [J.A. Cohen and V.A. Khorosheva, Colloids Surf. A 195, 113 (2001)]. The experimental data are interpreted by drawing upon self-consistent mean-field calculations of the polymer segment density distributions and numerically exact solutions of the governing transport equations [R.J. Hill, D.A. Saville, and W.B. Russel, J. Colloid Interface Sci. 258, 56 (2003)]. The approach leads to excellent agreement between theory and experiment with one adjustable parameter--the hydrodynamic size (Stokes radius) a(s) approximately equal to 0.175 A of the statistical PEG segments with (Kuhn) length l=7.1 A . The remarkably small Stokes radius is demonstrated to be consistent with other applications of the well-known Debye-Brinkman model and, consequently, this work reveals important limitations of the mean-field hydrodynamic model. Despite such limitations, the "full" electrokinetic model is robust in its predictive capacity. The molecular weights of the terminally anchored PEG span the range where the coatings undergo a transition from mushroomlike to brushlike conformations, and the hydrodynamic size and electrophoretic mobility of the liposomes are demonstrated to be sensitive to the PEG chain length and the effects of double-layer polarization. PMID:15600617

Hill, Reghan J

2004-11-01

286

Effect of crop residue incorporation on soil organic carbon (SOC) and greenhouse gas (GHG) emissions in European agricultural soils  

NASA Astrophysics Data System (ADS)

Soil organic matter (SOM) improves soil physical (e.g. increased aggregate stability), chemical (e.g. cation exchange capacity) and biological (e.g. biodiversity, earthworms) properties. The sequestration of soil organic carbon (SOC) may mitigate climate change. However, as much as 25-75% of the initial SOC in world agricultural soils may have been lost due to intensive agriculture (Lal, 2013). The European Commission has described the decline of organic matter (OM) as one of the major threats to soils (COM(2006) 231). Incorporation of crop residues may be a sustainable and cost-efficient management practice to maintain the SOC levels and to increase soil fertility in European agricultural soils. Especially Mediterranean soils that have low initial SOC concentrations, and areas where stockless croplands predominate may be suitable for crop residue incorporation. In this study, we aim to quantify the effects of crop residue incorporation on SOC and GHG emissions (CO2 and N2O) in different environmental zones (ENZs, Metzger et al., 2005) in Europe. Response ratios for SOC and GHG emissions were calculated from pairwise comparisons between crop residue incorporation and removal. Specifically, we investigated whether ENZs, clay content and experiment duration influence the response ratios. In addition, we studied how response ratios of SOM and crop yields were correlated. A total of 718 response ratios (RR) were derived from a total of 39 publications, representing 50 experiments (46 field and 4 laboratory) and 15 countries. The SOC concentrations and stocks increased by approximately 10% following crop residue incorporation. In contrast, CO2 emissions were approximately six times and N2O emissions 12 times higher following crop residue incorporation. The effect of ENZ on the response ratios was not significant. For SOC concentration, the >35% clay content had significantly approximately 8% higher response ratios compared to 18-35% clay content. As the duration of the experiment rose, RR for SOC concentration and stock increased. For N2O emissions, RR was significantly higher in <5 years experiment duration compared to 11-15 years experiment duration. For GHG emissions, the RRs were significantly higher when vegetable crop residues were incorporated instead of cereal crop residues. No significant correlations were found between RR for SOC concentration and yields, but differences between sites could be detected. We conclude that crop residue incorporation is an important management practice for maintaining SOC concentrations and stocks. Its influence in increasing GHG emissions should not be overlooked as the data availability from field experiments on GHG emissions is still scarce.

Lehtinen, Taru; Schlatter, Norman; Baumgarten, Andreas; Bechini, Luca; Krüger, Janine; Grignani, Carlo; Zavattaro, Laura; Costamagna, Chiara; Spiegel, Heide

2014-05-01

287

Principles of Micellar Electrokinetic Capillary Chromatography Applied in Pharmaceutical Analysis  

PubMed Central

Since its introduction capillary electrophoresis has shown great potential in areas where electrophoretic techniques have rarely been used before, including here the analysis of pharmaceutical substances. The large majority of pharmaceutical substances are neutral from electrophoretic point of view, consequently separations by the classic capillary zone electrophoresis; where separation is based on the differences between the own electrophoretic mobilities of the analytes; are hard to achieve. Micellar electrokinetic capillary chromatography, a hybrid method that combines chromatographic and electrophoretic separation principles, extends the applicability of capillary electrophoretic methods to neutral analytes. In micellar electrokinetic capillary chromatography, surfactants are added to the buffer solution in concentration above their critical micellar concentrations, consequently micelles are formed; micelles that undergo electrophoretic migration like any other charged particle. The separation is based on the differential partitioning of an analyte between the two-phase system: the mobile aqueous phase and micellar pseudostationary phase. The present paper aims to summarize the basic aspects regarding separation principles and practical applications of micellar electrokinetic capillary chromatography, with particular attention to those relevant in pharmaceutical analysis.

Hancu, Gabriel; Simon, Brigitta; Rusu, Aura; Mircia, Eleonora; Gyeresi, Arpad

2013-01-01

288

Successful Incorporation of Pseudo-Ceramides into Emulsions at Effective Concentrations  

Microsoft Academic Search

The incorporation of pseudo-ceramide (SLE), analogous in structure to natural occurring ceramide Type II, into an emulsion for skincare treatment was investigated. As SLE is water insoluble and not sufficiently oil soluble, resulting concentrations in emulsions were only 1.25%—too low for skin treatment. Stable lamellar structures formed with stearic acid did not have sufficient affinity for water to allow emulsification.

Hidetaka Iwai; Junichi Fukasawa; Toshiyuki Suzuki

1997-01-01

289

Nitrogen incorporation effects on gain properties of GaInNAs lasers : experiment and theory.  

SciTech Connect

Gain properties of GaInNAs lasers with different nitrogen concentrations in the quantum wells are investigated experimentally and theoretically. Whereas nitrogen incorporation induces appreciable modifications in the spectral extension and the carrier density dependence of the gain, it is found that the linewidth enhancement factor is reduced by inclusion of nitrogen, but basically unaffected by different nitrogen content due to the balancing between gain and index changes.

Thranhardt, A. (Fachbereich Physik, Marburg, Germany); Mawst, L. J. (University of Wisconsin-Madison, Madison, WI); Hader, J. (University of Arizona, Tucson, AZ); Schlichenmaier, C. (Fachbereich Physik, Marburg, Germany); Tansu, N. (Lehigh Unversity, Bethlehem, PA); Yeh, J. -Y. (University of Wisconsin-Madison, Madison, WI); Belenky, G. (State University of New York at Stony Brook, Stony Brook, NY); Chow, Weng Wah; Shterengas, L. (State University of New York at Stony Brook, Stony Brook, NY); Moloney, Jerome V. (University of Arizona, Tucson, AZ); Koch, S. W. (Fachbereich Physik, Marburg, Germany); Kuznetsova, I. (Fachbereich Physik, Marburg, Germany)

2005-05-01

290

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

291

Incorporating the effects of habitat edges into landscape models: Effective area models for cross-boundary management.  

SciTech Connect

Sisk, T.D., and N.M. Haddad. 2002. Incorporating the effects of habitat edges into landscape models: Effective area models for cross-boundary management. Chapter 8, Pp. 208-240 in J. Liu and W.W. Taylor, Integrating landscape ecology into natural resource management, Cambridge University Press, Cambridge, UK. Abstract: Natural resource managers are increasingly charged with meeting multiple, often conflicting goals in landscapes undergoing significant change due to shifts in land use. Conservation from native to anthropogenic habitats typically fragments the landscape, reducing the size and increasing the isolation of the resulting patches, with profound ecological impacts. These impacts occur both within and adjacent to areas under active management, creating extensive edges between habitat types. Boundaries established between management areas, for example, between timber harvest units or between reserves and adjacent agricultural fields, inevitably lead to differences in the quality of habitats on either side of the boundary, and a habitat edge results. Although edges are common components of undisturbed landscapes, the amount of edge proliferates rapidly as landscapes are fragmented. Insightful analysis of the complex issues associated with cross-boundary management necessitates an explicit focus on habitat quality in the boundary regions.

T.D. Sisk; N.M. Haddad

2002-01-01

292

Electrokinetic settling and sedimentation behavior of cohesive soils in dilute suspension.  

PubMed

In this study, the electrokinetic (EK) effects on settling behavior of clayey soils under different electrolyte solution, electric field strength, and moisture content were evaluated using kaolin and natural marine clay. A number of laboratory-scale column experiment were carried out in order to examine the effects of electrophoresis and electro-osmosis during settling processes. The settling velocity under different electrolyte solution was found to become faster resulting from the formation of floc due to the contraction of electrical double layer. The electrically induced surface settlement was faster in settling rate and greater in magnitude by comparison with that under the conventional gravitational sedimentation. The effects of electrophoresis on settling behavior become significant from the beginning of hindered settling stage due to the influence of electrochemical interactions between the charged clay particles. PMID:18569311

Kim, Soo Sam; Lee, Myungho; Kim, Dae-Ho

2008-07-01

293

Antifungal effectiveness of potassium sorbate incorporated in edible coatings against spoilage molds of apples, cucumbers, and tomatoes during refrigerated storage.  

PubMed

Predominant spoilage molds of fresh apples, cucumbers, and tomatoes stored at 4 °C were isolated and examined for resistance to potassium sorbate (PS) incorporated in polysaccharide edible coatings. The isolated molds were?Penicillium expansum, Cladosporium herbarum, and?Aspergillus niger?from apples.?P. oxalicum?and?C. cucumerinum?were isolated from cucumbers and?P. expansium?and?C. fulvum?from tomatoes. Guar gum edible coating incorporated with PS was the most effective mold inhibitor, significantly (P<0.05) reducing the isolated spoilage molds for 20, 15, and 20 d of storage at 4 °C on apples, cucumbers, and tomatoes, respectively. PS incorporated into pea starch edible coating was less effective and selectively inhibited the isolated mold species, causing significant (P<0.05) reduction in mold on apples, cucumbers, and tomatoes counts for 20, 10 to 15, and 15 to 20 d of storage at 4 °C, respectively. The isolated mold species exhibited different resistances to PS incorporated in the edible coatings. The greatest inhibition (2.9 log CFU/g) was obtained with?C. herbarum?on apples and the smallest (1.1 log CFU/g) was with?P.?oxalicum?on cucumbers and the other isolated mold species exhibited intermediate resistance. The coatings tested, in general, inhibited molds more effectively on apples than on tomatoes and cucumbers. Addition of PS to pea starch and guar gum, edible coatings improved the antifungal activity of PS against isolated spoilage molds on apples, cucumbers, and tomatoes. PS inhibition was most effective against?C. herbarum?on apples and least effective against?P.?oxalicum?on cucumbers. PMID:21535846

Mehyar, Ghadeer F; Al-Qadiri, Hamzah M; Abu-Blan, Hifzi A; Swanson, Barry G

2011-04-01

294

An Improved Method for Calculating Zeta-Potentials from Measurements of the Electrokinetic Sonic Amplitude  

Microsoft Academic Search

The surface electric properties of the commercially available silica, Monospher 1000 (Fa. Merck), have been studied by conductivity and ESA (electrokinetic sonic amplitude) experiments. It could be shown that accounting for the contribution of the stagnant layer to surface conductivity is indispensable in the interpretation of electrokinetic data at low ionic strength. A general method has been put forward which

Mario Löbbus; Jürgen Sonnfeld; Herman P. van Leeuwen; Wolfram Vogelsberger; Johannes Lyklema

2000-01-01

295

Removal of chromium, nickel and cadmium from clays by in?situ electrokinetic remediation  

Microsoft Academic Search

This article presents the results of a research study that investigated the use of the in situ electrokinetic process for removing chromium, nickel, and cadmium from contaminated clays. For this study, electrokinetic experiments were conducted on two types of clays: kaolin, a commercial?grade soil consisting mainly of kaolinite clay mineral, and glacial till, a fíeld derived clay that possesses a

Krishna R. Reddy; Usha S. Parupudi

1997-01-01

296

Stability and electrokinetic potential of silicon carbide suspensions in aqueous organic media  

NASA Technical Reports Server (NTRS)

The method of electroosmosis was used to study the dependence of the electrokinetic potential of silicon carbide suspensions in mixtures of water -n. alcohol. The reasons for the dependence of the electrokinetic potential on the composition of the intermicellar liquid are discussed.

Yeremenko, B. V.; Lyubchenko, I. N.; Skobets, I. Y.

1984-01-01

297

Mitigation of methane emissions from rice fields: Possible adverse effects of incorporated rice straw  

NASA Astrophysics Data System (ADS)

Increased world demand for rice production may lead to an increase in methane emission to the atmosphere and future global warming. One suggested way to reduce methane emission is to discourage the practice of incorporating previous crop residue prior to planting rice, since the residue may enhance methane emission from flooded rice fields. This concept is supported by data from a 2-year study of flooded rice fields on two different soil types in Texas. In 1990, rice stubble from 1989 was incorporated into both soils. Seasonal methane emission from a Lake Charles clay field increased from 15.9 g m-2 in 1989 to 31.0 g m-2 in 1990. In the Beaumont clay field, seasonal methane emission increased from 4.5 to 11.4 g m-2. While methane emission increased between 1989 and 1990, grain yield dropped by 2100 and 840 kg ha-1 in the Lake Charles and Beaumont fields, respectively. Visual inspection at harvest indicated that the 1990 rice yield decrease resulted from grain abortion, presumably caused by the rice cultivar's sensitivity to soil anaerobiosis. The calculated amount of organic carbon not translocated to grain was comparable to the estimated amount of organic carbon required for the increased methane emission. We hypothesize that labile carbon in straighthead susceptible rice cultivars can "leak" from roots damaged by excessively anaerobic soil and be metabolized to its equivalent in methane. These data suggest that minimizing incorporation of crop residue prior to planting can decrease methane emission from flooded rice and reduce the potential for yield loss, particularly with some cultivars and in soils with low rates of seepage and percolation.

Sass, R. L.; Fisher, F. M.; Harcombe, P. A.; Turner, F. T.

1991-09-01

298

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

299

Tissue lead distribution and hematologic effects in american kestrels Falco sparverius fed biologically incorporated lead  

USGS Publications Warehouse

American kestrels were fed a diet containing 0.5, 120, 212 and 448 ppm (dry wt) biologically incorporated Pb for 60 days. The diet consisted of homogenized 4-wk-old cockerels raised on feed mixed with and without Pb. No kestrels died and weights did not differ among treatment groups. The control group (0.5 ppm Pb) had the lowest mean concentration of Pb and the high dietary group had the highest for the following tissues: kidney, liver, femur, brain and blood. Concentrations of Pb were significantly correlated among tissues. Treatment groups did not differ in packed cell volume, Hb concentration or erythrocyte count.

Custer, T. W.; Franson, J. C.; Pattee, O. H.

1984-01-01

300

Tissue lead distribution and hematologic effects in American kestrels (Falco sparverius) fed biologically incorporated lead  

USGS Publications Warehouse

American kestrels were fed a diet containing 0.5, 120, 212, and 448 ppm (dry wt) biologically incorporated lead (Pb) for 60 days. The diet consisted of homogenized 4-wk-old cockerels raised on feed mixed with and without lead. No kestrels died and weights did not differ among treatment groups. The control group (0.5 ppm Pb) had the lowest mean concentration of lead and the high dietary group had the highest for the following tissues: Kidney, liver, femur, brain, and blood. Concentrations of lead were significantly correlated among tissues. There were no differences among treatment groups for packed cell volume, hemoglobin concentration, or erythrocyte count.

Custer, T.W.; Franson, J.C.; Pattee, O.H.

1984-01-01

301

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

302

The effect of grinding process on mechanical properties and alkali–silica reaction resistance of fly ash incorporated cement mortars  

Microsoft Academic Search

The effect of fineness of fly ash on mechanical properties and alkali–silica reaction resistance of cement mortar mixtures incorporating fly ash has been investigated within the scope of this study. Blaine fineness of fly ash has been increased to 907m2\\/kg from its original 290m2\\/kg value by a ball mill. Test samples were prepared by replacing cement 20, 40 and 60%,

Serdar Ayd?n; Çaglayan Karatay; Bülent Baradan

2010-01-01

303

Phosphorus incorporation during Si(001):P gas-source molecular beam epitaxy: Effects on growth kinetics and surface morphology  

Microsoft Academic Search

The effects of P doping on growth kinetics and surface morphological evolution during Si(001):P gas-source molecular beam epitaxy from Si2H6 and PH3 at temperatures Ts=500-900 °C have been investigated. With increasing PH3\\/Si2H6 flux ratio JP\\/Si at constant Ts, we observe a decrease in the film growth rate R and an increase in the incorporated P concentration CP, both of which

B. Cho; J. Bareño; Y. L. Foo; S. Hong; T. Spila; I. Petrov; J. E. Greene

2008-01-01

304

Annealing Effect of W Incorporated Diamond-Like Carbon Fabricated by Ga Focused Ion Beam Chemical Vapor Deposition  

Microsoft Academic Search

The effects of thermal annealing of W incorporated diamond-like carbon (W-DLC) films fabricated with focused ion beam chemical vapor deposition (FIB-CVD) were investigated using X-ray absorption fine structure near the carbon K-edge (C-K NEXAFS) and the combination of Rutherford backscattering (RBS) and elastic recoil detection analysis (ERDA). W-DLC films were annealed for 32 h at temperatures, Ta, between 673 and

Akira Wada; Tsuneo Suzuki; Masahito Niibe; Haruhiko Ito; Kazuhiro Kanda

2011-01-01

305

High figure of merit for electrokinetic energy conversion in Nafion membranes  

NASA Astrophysics Data System (ADS)

Based on measurements of the streaming potential coefficient, hydraulic permeability and ion conductivity the electrokinetic energy conversion of nanoporous ion conductive Nafion®117 polymer membrane has been evaluated. A high figure-of-merit of 1.1 ± 0.2 has been found in 0.03 M aqueous LiCl solution that corresponds to an electrokinetic energy conversion efficiency of approximately 18 ± 2%. To the best of our knowledge, this is the first study in the literature designated to the electrokinetic energy conversion in materials where the pores have high surface charge density. The initial results are promising with respect to future electrokinetic generator or pump applications and highly charged polymer membranes might be a future pathway for low-cost high-efficiency electrokinetic energy conversion.

Kilsgaard, Bjørn Sjøgren; Haldrup, Sofie; Catalano, Jacopo; Bentien, Anders

306

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

2013-05-01

307

Effects of incorporating germinated brown rice on the antioxidant properties of wheat flour chapatti.  

PubMed

Brown rice after germinating for 24 and 48?h was milled into flour and incorporated in whole wheat flour at a level of 10% to prepare chapattis. The objective was to use chapatti as a delivery vehicle for germinated brown rice. The flour blends and chapattis made from the flour blends were evaluated for their antioxidant properties. Incorporating germinated brown rice flour increased the total phenolic content of the flour blend from 1897 to 2144?µg FAE/g. The total flavonoids content increased significantly from 632.3 to1770.9?µg CAE/g and metal chelating activity significantly increased by 71.62%. Antioxidant activity increased significantly by the addition of brown rice flour and addition of 24- and 48-h germinated brown rice flour further increased the antioxidant activity significantly. The total phenolic content and total flavonoids content decrease significantly in all the blends after baking the flour into chapatti. A decrease of 3% to 29% was observed in the total phenolic content and a decrease of 25% to 42% was observed in the total flavonoids content. However, baking of the flour blends into chapatti increased the reducing power, metal chelating activity by three folds and antioxidant activity from 64% to 104%. PMID:22328119

Gujral, H Singh; Sharma, P; Bajaj, R; Solah, V

2012-02-01

308

Quantitative Determination of Lattice Fluoride Effects on the Solubility and Crystallinity of Carbonated Apatites with Incorporated Fluoride  

PubMed Central

The purpose of this study was to evaluate quantitatively the effects of fluoride on the solubility and crystallinity of carbonated apatites (CAPs) after its incorporation into the crystal lattice using the metastable equilibrium solubility (MES) distribution method. Fluoride incorporated CAPs (F-CAPs) of two different carbonate levels (3% and 5%) and fluoride contents from 0 to 20,000 ?g/g were synthesized. X-ray diffraction experiments and Rietveld analysis were conducted to obtain crystallite microstrain and unit cell parameters. Acetate buffer MES solution media were prepared at two solution fluoride concentrations (0.2 mg/L and 2.0 mg/L) and at two pHs (5.0 and 5.7). The unit cell a-axis values of the F-CAPs were found to decrease as the fluoride content increased; consistent with the fluoride being incorporated into the crystal lattice. The fluoride concentrations in the MES solution media were high enough to provide a “swamping” effect such that the fluoride released from the F-CAPs during dissolution was minimal in changing the solution fluoride concentration. Employing the MES distribution superposition method, it was shown that the surface complex possessing the fluorapatite (FAP) stoichiometry (Ca10(PO4)6F2) accounted for the MES distribution behavior of all experiments. In addition, the mean pIFAP [the value of ?log(aca 10PO46aF2) calculated from ionic activity product based on FAP stoichiometry of the MES dissolution media in which 50% of the F-CAP had dissolved] correlated well with the crystallite microstrain parameters of the F-CAPs. The incorporated fluoride in the F-CAPs showed only modest effects on F-CAP crystallinity and solubility.

Yan, Guang; Moribe, Kunikazu; Otsuka, Makoto; Papangkorn, Kongnara; Higuchi, William I.

2013-01-01

309

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

310

Effects of nucleoside analog incorporation on DNA binding to the DNA binding domain of the GATA-1 erythroid transcription factor.  

PubMed

We investigate here the effects of the incorporation of the nucleoside analogs araC (1-beta-D-arabinofuranosylcytosine) and ganciclovir (9-[(1,3-dihydroxy-2-propoxy)methyl] guanine) into the DNA binding recognition sequence for the GATA-1 erythroid transcription factor. A 10-fold decrease in binding affinity was observed for the ganciclovir-substituted DNA complex in comparison to an unmodified DNA of the same sequence composition. AraC substitution did not result in any changes in binding affinity. 1H-15N HSQC and NOESY NMR experiments revealed a number of chemical shift changes in both DNA and protein in the ganciclovir-modified DNA-protein complex when compared to the unmodified DNA-protein complex. These changes in chemical shift and binding affinity suggest a change in the binding mode of the complex when ganciclovir is incorporated into the GATA DNA binding site. PMID:10037146

Foti, M; Omichinski, J G; Stahl, S; Maloney, D; West, J; Schweitzer, B I

1999-02-01

311

Effect of thickness on the microstructure, surface morphology and optical properties of N-incorporated ?-Ga2O3 films  

NASA Astrophysics Data System (ADS)

To investigate the effect of thickness on the microstructure, surface morphology and optical properties of N-incorporated ?-Ga2O3 films, a series of N-incorporated ?-Ga2O3 samples with different thicknesses were prepared by radio frequency (RF) magnetron sputtering method. X-ray diffraction measurements show that the crystallinity quality was improved by increasing the film thickness. Atomic force microscopy results show that the surface exhibits hillock and island morphology under different film thicknesses. The optical transmittance of all samples is more than 80% in the visible range. The UV absorption edge shifts to longer wavelength, and the small change in the optical band gap value is due to the improved crystallinity of the films.

Sun, Rui; Zhang, Hua-Yu; Wang, Gui-Gen; Han, Jie-Cai; Wang, Xin-Zhong; Cui, Lin; Kuang, Xu-Ping; Zhu, Can; Jin, Lei

2014-01-01

312

Annealing Effect of W Incorporated Diamond-Like Carbon Fabricated by Ga Focused Ion Beam Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

The effects of thermal annealing of W incorporated diamond-like carbon (W-DLC) films fabricated with focused ion beam chemical vapor deposition (FIB-CVD) were investigated using X-ray absorption fine structure near the carbon K-edge (C-K NEXAFS) and the combination of Rutherford backscattering (RBS) and elastic recoil detection analysis (ERDA). W-DLC films were annealed for 32 h at temperatures, Ta, between 673 and 1073 K. Comparing the Ta dependences of Ga and H contents obtained from RBS-ERDA and the sp2/(sp2 + sp3) ratios from C-K NEXAFS, it was found that even a trace amount of W incorporation into DLC films fabricated by Ga+ FIB-CVD may cause a significant sp3 ? sp2 structural change.

Wada, Akira; Suzuki, Tsuneo; Niibe, Masahito; Ito, Haruhiko; Kanda, Kazuhiro

2011-06-01

313

Modulation of the effective work function of a TiN metal gate for NMOS requisition with Al incorporation  

NASA Astrophysics Data System (ADS)

The effect of Al incorporation on the effective work function (EWF) of TiN metal gate was systematically investigated. Metal—oxide—semiconductor (MOS) capacitors with W/TiN/Al/TiN gate stacks were used to fulfill this purpose. Different thickness ratios of Al to TiN and different post metal annealing (PMA) conditions were employed. Significant shift of work function towards to Si conduction band was observed, which was suitable for NMOS and the magnitude of shift depends on the processing conditions.

Kai, Han; Xueli, Ma; Hong, Yang; Wenwu, Wang

2013-07-01

314

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

315

Electrokinetic characteristic and coagulation behavior flocculant polyaluminum silicate chloride (PASiC).  

PubMed

The electrokinetic characteristics and coagulation behaviors of polyaluminum silicate chloride (PASiC) and polyaluminum chloride (PAC) were studied and compared by streaming current (SC) measurement and jar test method. The experimental results showed that the interaction between polysilicic acid characterized negative charge and hydrolyzed aluminum species result in a decrease of the charge-neutralizing ability of PASiC, compared to PAC. The decrease has a close relationship with the basicity (B) and Al/Si molar ratio in PASiC. The less the B value and the Al/Si molar ratio, the lower the charge-neutralizing ability of PASiC is. In contrast, the preparation technique for PASiC affects the charge - neutralization of PASiC to a smaller extent. In addition, compared with PAC, PASiC may enhance aggregating efficiency and give better coagulating effects. PMID:12602606

Yue, Qin-Yan; Gao, Bao-Yu; Wang, Bing-Jian

2003-01-01

316

Microemulsion electrokinetic chromatographic determination of bufadienolides in toad venom and in traditional Chinese medicine.  

PubMed

A microemulsion electrokinetic chromatographic (MEEKC) method has been developed and validated for determination of resibufogenin and cinobufagin in toad venom and in traditional Chinese medicine prepared from the venom. The MEEKC method involved use of sodium dodecyl sulfate (SDS) as surfactant, heptane as organic solvent, and butan-1-ol as co-solvent. To improve the separation, the effect of temperature and running buffer pH were evaluated. The optimized conditions (heptane 0.81% (w/w), SDS 3.31% (w/w), butan-1-ol 6.61% (w/w), and 10 mmol L(-1) sodium tetraborate buffer, pH 9.2, and 298 nm as the detection wavelength) enabled useful and repeatable separation of the analytes. PMID:16477424

Xingping, Luo; Zongde, Zhai; Yanfang, Zhao; Liren, Chen; Yongmin, Li

2006-03-01

317

Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils  

DOEpatents

An electrokinetic electrode assembly is described for use in extraction of soil contaminants from unsaturated soil in situ. The assembly includes a housing for retaining a liquid comprising an electrolyte solution, pure water, and soil water, the housing being in part of porous material capable of holding a vacuum. An electrode is mounted in the housing. The housing is provided with a vacuum orifice for effecting a vacuum within the housing selectively to control flow of soil water through the housing into the chamber and to control outflow of the liquid from the chamber. The assembly further includes conduit means for removing the liquid from the housing and returning the electrolyte solution to the housing, and a conduit for admitting pure water to the housing. An electrode system and method are also revealed for extraction of soil contaminants. The system and method utilize at least two electrode assemblies as described above. 5 figs.

Lindgren, E.R.; Mattson, E.D.

1995-07-25

318

Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils  

DOEpatents

There is presented an electrokinetic electrode assembly for use in extraction of soil contaminants from unsaturated soil in situ. The assembly includes a housing for retaining a liquid comprising an electrolyte solution, pure water, and soil water, the housing being in part of porous material capable of holding a vacuum. An electrode is mounted in the housing. The housing is provided with a vacuum orifice for effecting a vacuum within the housing selectively to control flow of soil water through the housing into the chamber and to control outflow of the liquid from the chamber. The assembly further includes conduit means for removing the liquid from the housing and returning the electrolyte solution to the housing, and a conduit for admitting pure water to the housing. There is further presented an electrode system and method for extraction of soil contaminants, the system and method utilizing at least two electrode assemblies as described above.

Lindgren, Eric R. (Albuquerque, NM); Mattson, Earl D. (Albuquerque, NM)

1995-01-01

319

Comparative study of the effect of incorporated individual wheat storage proteins on mixing properties of rice and wheat doughs.  

PubMed

The aim of this work was to compare the effects of incorporated wheat storage proteins on the functional properties of rice and wheat flours. The advantage of rice as a base flour compared to wheat is that it does not contain any wheat flour components and, therefore, has no interactive effect between wheat glutenin proteins. The incorporation of individual HMW glutenin subunit proteins (Bx6, Bx7, and By8) in different ratios had significant positive effects on the mixing requirements of both rice and wheat doughs. Reconstitution experiments using two x+y type HMW-GS pairs together with a bacterially expressed LMW-GS have been also carried out in this study. The largest effects of polymer formation and mixing properties of rice flour dough were observed when Bx and By subunits were used in a 1:1 ratio and HMW and LMW glutenin subunits in a 1:3 ratio. However, using the same subunit ratios in wheat as the base flour, these synergistic effects were not observed. PMID:21815607

Oszvald, Mária; Balázs, Gábor; Tömösközi, Sándor; Békés, Ferenc; Tamás, László

2011-09-14

320

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

321

Effect of nickel incorporation on microstructural and optical properties of electrodeposited diamond like carbon (DLC) thin films  

NASA Astrophysics Data System (ADS)

A simple electrodeposition technique was used to synthesize diamond like carbon (DLC) and nickel incorporated diamond like carbon (Ni-DLC) thin films on ITO coated glass substrates. Initial concentration of nickel in the electrolyte was kept fixed at 4.76 × 10-4 M for all depositions of Ni-DLC films. Growth process of the films was studied by synthesizing films with variation of deposition time. With nickel addition to DLC the band gap and the Urbach energy varied from 2.67 eV to 2.48 eV and 1.0803 eV to 1.452 eV, respectively as estimated from UV-vis-NIR spectrophotometry of DLC and Ni-DLC. Results indicated that the metal incorporation effectively increased the graphitization of DLC films. Microstructural studies by SEM and AFM revealed that the particles in the Ni-DLC films were evenly distributed and the packing density of particles increased with increased time of deposition. XRD pattern exhibited the presence of Ni crystallites in an amorphous carbon network along with the phases of diamond and graphite in the Ni-DLC film. The FTIR spectrum showed peaks accountable for both CH3 and CH2 bonding. It was also apparent that nickel incorporation significantly modulated the FTIR spectrum of DLC film, as several new peaks appeared only in the case of Ni-DLC film at ˜776 cm-1, 745 cm-1 and 668 cm-1.

Pandey, B.; Pal, P. P.; Bera, S.; Ray, S. K.; Kar, A. K.

2012-11-01

322

Electrokinetic concentration of DNA polymers in nanofluidic channels.  

PubMed

DNA molecules can be concentrated in a narrow region of a nanochannel when driven electrokinetically in submillimolar salt solutions. Transport experiments and theoretical modeling reveal the interplay of electrophoresis, electro-osmosis, and the unique statistical properties of confined polymers that lead to DNA aggregation. A finite conductance through the bulk of the device also plays a crucial role by influencing the electric fields in the nanochannel. We build on this understanding by demonstrating how a nanofluidic device with integrated electrodes can preconcentrate DNA at selected locations and at physiological salt concentrations that are relevant to lab-on-a-chip applications. PMID:20151696

Stein, Derek; Deurvorst, Zeno; van der Heyden, Frank H J; Koopmans, Wiepke J A; Gabel, Alan; Dekker, Cees

2010-03-10

323

Separation of xylidine isomers by micellar electrokinetic chromatography.  

PubMed

Xylidines are important precursors for the production of dyes, drugs, and various other products. Because of the high carcinogenic nature of some xylidine isomers it becomes very essential and relevant to develop suitable analytical procedures to separate isomers as well as enhance detection at very low concentrations. Micellar electrokinetic chromatography has been standardized at various influencing parameters such as pH, ionic strength, and micelle modifiers, and the optimum conditions have been ascertained for the best separation and sensitivity of standard mixtures. The applicability of the procedure in environmental samples is studied. PMID:11513275

Jeevan, R J; Chandrasekar, R; Bhaskar, M; Radhakrishana, G

2001-08-01

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

Effects of incorporation of fluorocarbon and hydrocarbon surfactants into perfluorosulfonic acid (Nafion) membranes  

SciTech Connect

Perfluorinated ionomer membranes such as Nafion have numerous uses in both industrial chemical practice and in chemical research. Applications include the chloralkali process, H[sub 2]/O[sub 2] fuel cells, biomedical sensing, and other types of chemical sensors based on modified electrodes. Significant permeability improvements can be made to perfluorinated ionomer films by incorporating sulfonated surfactants of suitable size into the membrane microstructure. A variety of 20-[mu]m composite Nafion/surfactant membranes were prepared from DMF casting solutions containing Nafion and the sodium salts of perfluoro-1-butanesulfonic acid (perf-ButSO[sub 3]Na), perfluoro-1-octanesulfonic acid (perf-OctSO[sub 3]Na) and 1-octanesulfonic acid (OctSO[sub 3]Na). The time required for 50% extraction of the surfactants from the membranes into water was 1 min for OctSO[sub 3]Na, 5 min for perf-ButSO[sub 3]Na, and approximately 3 days for perf-OctSO[sub 3]Na. Extraction of perf-OctSO[sub 3]Na into isooctane contacting solutions was not observable over periods of days. For membranes containing surfactants and exchanged with silver(I) ion, 3-fold permeability improvements can be obtained for the separation of 1,5-hexadiene from 1-hexene and n-hexane without any decreases in separation factors. Observed flux improvements are larger than the increase in ion-exchange site density and are attributed to increased mobility of olefins between carrier sites due to the presence of specific surfactants. Results indicate that movement of olefins in Nafion occurs primarily through an interfacial region of the film structure. The ability of a surfactant to improve transport performance is dependent on its ability to partition into the interfacial region. 27 refs., 3 figs., 2 tabs.

Rabago, R.; Noble, R.D.; Koval, C.A. (Univ. of Colorado, Boulder, CO (United States))

1994-07-01

326

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

NASA Astrophysics Data System (ADS)

This work describes the composition and bonding structure of hydrogenated carbon nitride (a-CNx: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-CNx:H films with N/C contents varying from 0.06 to 0.49 were obtained. Remarkably, the H content of the films (~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.; Gómez-Aleixandre, C.; Gago, R.; Caretti, I.; Jiménez, I.

2007-03-01

327

Effect of the Folic Acid Analogue, Trimethoprim, on Growth, Macromolecular Synthesis, and Incorporation of Exogenous Thymine in Escherichia coli1  

PubMed Central

The effect of trimethoprim [2,4-diamino-5(2?,4?,5?trimethoxybenzyl)-pyrimidine] in the presence of thymine on Escherichia coli B temperature-sensitive and non-temperature-sensitive Thy? strains and a phosphodeoxyribomutase-negative mutant was studied. The inhibitory effect of 5 ?g of trimethoprim per ml on the growth of E. coli B was not overcome by thymine, thymidine, or thymidylate even in the presence of one-carbon metabolites and related metabolites. Deoxyribonucleic acid (DNA) and protein synthesis were more severely inhibited than ribonucleic acid (RNA) synthesis. The inhibition of DNA synthesis was partially reversed by addition of deoxyadenosine to increase the incorporation of exogenous thymine. By contrast, the inhibition of protein was not reversed even with one-carbon metabolites present, in keeping with the requirement for formylmethionyl-transfer RNAF for initiation. However, the inhibition of both DNA and protein synthesis in a phosphodeoxyribomutase-negative strain by 1 ?g of trimethoprim per ml with thymine present was partially reversed by deoxyadenosine and one-carbon metabolites, and nearly normal growth occurred. 5-Fluorodeoxyuridine added at the time of addition of trimethoprim prevented the inhibition. Sulfadiazine in the presence of thymine inhibited both Thy+ and Thy? strains whereas trimethoprim (with thymine) did not inhibit Thy? organisms. The effect of trimethoprim on the incorporation of labeled thymine into DNA was also studied. These experiments support the concept that trimethoprim in conjunction with the action of thymidylate synthetase inhibits the growth of Thy+ cells because of a depletion of tetrahydrofolate. DNA synthesis is inhibited initially by a limitation of thymine nucleotide precursor, resulting from the indirect inhibition of thymidylate synthetase and the poor incorporation of exogenous thymine.

Dale, Beverly A.; Greenberg, G. Robert

1972-01-01

328

Field Testing of High Current Electrokinetic Nanoparticle Treatment for Corrosion Mitigation in Reinforced Concrete  

NASA Technical Reports Server (NTRS)

Electrokinetic Nanoparticle (EN) treatment was used as a rapid repair measure to mitigate chloride induced corrosion of reinforced concrete in the field. EN treatment uses an electric field to transport positively charged nanoparticles to the reinforcement through the concrete capillary pores. Cylindrical reinforced concrete specimens were batched with 4.5 wt % salt content (based on cement mass). Three distinct electrokinetic treatments were conducted using high current density (up to 5 A/m2) to form a chloride penetration barrier that was established in 5 days, as opposed to the traditional 6-8 weeks, generally required for electrochemical chloride extraction (ECE). These treatments included basic EN treatment, EN with additional calcium treatment, and basic ECE treatment. Field exposures were conducted at the NASA Beachside Corrosion Test Site, Kennedy Space Center, Florida, USA. The specimens were subjected to sea water immersion at the test site as a posttreatment exposure. Following a 30-day post-treatment exposure period, the specimens were subjected to indirect tensile testing to evaluate treatment impact. The EN treated specimens exhibited 60% and 30% increases in tensile strength as compared to the untreated controls and ECE treated specimens respectively. The surfaces of the reinforcement bars of the control specimens were 67% covered by corrosion products. In contrast, the EN treated specimens exhibited corrosion coverage of only 4%. Scanning electron microscopy (SEM) revealed a dense concrete microstructure adjacent to the bars of the treated specimens as compared to the control and ECE specimens. Energy dispersive spectroscopic (EDS) analysis of the polished EN treated specimens showed a reduction in chloride content by a factor of 20 adjacent to the bars. This study demonstrated that EN treatment was successful in forming a chloride penetration barrier rapidly. This work also showed that the chloride barrier was effective when samples were exposed to field conditions at one of the most severely corrosive environments in North America.

Cardenas, Henry; Alexander, Joshua; Kupwade-Patil, Kunal; Calle, Luz marina

2010-01-01

329

Large sensitivity enhancement in semiconducting organic field effect transistor sensors through incorporation of ultra-fine platinum nanoparticles  

NASA Astrophysics Data System (ADS)

We report remarkable improvement in sensitivity of pentacene-based field effect transistor devices towards trace nitro-aromatic explosive vapors through the incorporation of high density, sub-2 nm platinum nanoparticles (NPs) within these structures. Exploiting the unique electronic properties of these NPs, we have demonstrated a detection limit of 56.6 parts per billion of 2,4-dinitrotoluene (DNT) vapor while control samples without any embedded NPs showed no observable sensitivity to DNT vapor. We attribute this remarkable enhancement in sensitivity to the ability of these NPs to function as discrete nodes, participating in the charge transfer with adsorbed nitro-aromatic molecules.

Zheng, Haisheng; Ramalingam, Balavinayagam; Korampally, Venumadhav; Gangopadhyay, Shubhra

2013-11-01

330

A chemical mechanical polishing model incorporating both the chemical and mechanical effects  

Microsoft Academic Search

A comprehensive model for the material removal in a chemical mechanical polishing (CMP) process is presented in which both chemical and mechanical effects are taken into consideration. The chemical effects come into play through the formation of chemically modified surface layer on the wafer surface that, in turn, is removed mechanically by the plastic deformation induced by slurry particles. This

Kuide Qin; Brij Moudgil; Chang-Won Park

2004-01-01

331

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 ...

332

Rapid and label-free separation of Burkitt's lymphoma cells from red blood cells by optically-induced electrokinetics.  

PubMed

Early stage detection of lymphoma cells is invaluable for providing reliable prognosis to patients. However, the purity of lymphoma cells in extracted samples from human patients' marrow is typically low. To address this issue, we report here our work on using optically-induced dielectrophoresis (ODEP) force to rapidly purify Raji cells' (a type of Burkitt's lymphoma cell) sample from red blood cells (RBCs) with a label-free process. This method utilizes dynamically moving virtual electrodes to induce negative ODEP force of varying magnitudes on the Raji cells and RBCs in an optically-induced electrokinetics (OEK) chip. Polarization models for the two types of cells that reflect their discriminate electrical properties were established. Then, the cells' differential velocities caused by a specific ODEP force field were obtained by a finite element simulation model, thereby established the theoretical basis that the two types of cells could be separated using an ODEP force field. To ensure that the ODEP force dominated the separation process, a comparison of the ODEP force with other significant electrokinetics forces was conducted using numerical results. Furthermore, the performance of the ODEP-based approach for separating Raji cells from RBCs was experimentally investigated. The results showed that these two types of cells, with different concentration ratios, could be separated rapidly using externally-applied electrical field at a driven frequency of 50 kHz at 20 Vpp. In addition, we have found that in order to facilitate ODEP-based cell separation, Raji cells' adhesion to the OEK chip's substrate should be minimized. This paper also presents our experimental results of finding the appropriate bovine serum albumin concentration in an isotonic solution to reduce cell adhesion, while maintaining suitable medium conductivity for electrokinetics-based cell separation. In short, we have demonstrated that OEK technology could be a promising tool for efficient and effective purification of Raji cells from RBCs. PMID:24608811

Liang, Wenfeng; Zhao, Yuliang; Liu, Lianqing; Wang, Yuechao; Dong, Zaili; Li, Wen Jung; Lee, Gwo-Bin; Xiao, Xiubin; Zhang, Weijing

2014-01-01

333

Effects of Incorporating Nanosized Calcium Phosphate Particles on Properties of Whisker-Reinforced Dental Composites  

PubMed Central

Clinical data indicate that secondary caries and restoration fracture are the most common problems facing tooth restorations. Our ultimate goal was to develop mechanically-strong and caries-inhibiting dental composites. The specific goal of this pilot study was to understand the relationships between composite properties and the ratio of reinforcement filler/releasing filler. Nanoparticles of monocalcium phosphate monohydrate (MCPM) were synthesized and incorporated into a dental resin for the first time. Silicon carbide whiskers were fused with silica nanoparticles and mixed with the MCPM particles at MCPM/whisker mass ratios of 1:0, 2:1, 1:1, 1:2, and 0:1. The composites were immersed for 1–56 days to measure Ca and PO4 release. When the MCPM/whisker ratio was changed from 0:1 to 1:2, the composite flexural strength (mean ± SD; n = 5) decreased from 174 ± 26 MPa to 138 ± 9 MPa (p < 0.05). A commercial nonreleasing composite had a strength of 112 ± 14 MPa. When the MCPM/whisker ratio was changed from 1:2 to 1:1, the Ca concentration at 56 days increased from 0.77 ± 0.04 mmol/L to 1.74 ± 0.06 mmol/L (p < 0.05). The corresponding PO4 concentration increased from 3.88 ± 0.21 mmol/L to 9.95 ± 0.69 mmol/L (p < 0.05). Relationships were established between the amount of release and the MCPM volume fraction vMCPM in the resin: [Ca]= 42.9 vMCPM2.7, and [PO4] = 48.7 vMCPM1.4. In summary, the method of combining nanosized releasing fillers with reinforcing fillers yielded Ca- and PO4-releasing composites with mechanical properties matching or exceeding a commercial stress-bearing, nonreleasing composite. This method may be applicable to the use of other Ca–PO4 fillers in developing composites with high stress-bearing and caries-preventing capabilities, a combination not yet available in any dental materials.

Xu, Hockin H. K.; Sun, Limin; Weir, Mike D.; Takagi, Shozo; Chow, Laurence C.; Hockey, Bernard

2009-01-01

334

Effect of ambient storage on the quality characteristics of aerobically packaged fish curls incorporated with different flours.  

PubMed

The present study was conducted to evaluate the effect of ambient storage on the quality attributes of aerobically packaged fish curls incorporated with optimum levels of different flours. The curls were developed by extrusion technology using fish meat (Catla catla). The fish curls containing optimum levels of different flours viz. 20 percent corn flour, 10 percent black gram flour and 10 percent peanut flour were compared with the control snacks containing 30 percent rice flour and assessed for storage quality and shelf life at ambient temperature. The curls were aerobically packaged in LDPE (low density polyethylene) pouches and evaluated for various physicochemical, microbiological and sensory parameters. Mean values of pH of all the curls showed significantly (p?incorporated samples, 6.36?±?0.01 on day 0 and 6.14?±?0.01 on day 28 for black gram flour incorporated samples, 6.57?±?0.007 on day 0 and 6.34?±?0.01 on day 28 for peanut flour incorporated samples). TBARS (mg malonaldehyde/kg), total plate count (log cfu/g) and yeast and mould count (log cfu/g) for the control as well as treatment samples showed significantly (p?incorporated with optimum level of different flours were acceptable up to 21 days of ambient storage within the LDPE pouches. PMID:24624316

Raja, Waseem Hussain; Kumar, Sunil; Bhat, Zuhaib Fayaz; Kumar, Pavan

2014-01-01

335

Effects of Irradiation on Frozen Corticocancellous Bone Allograft Incorporation and Immunogenicity.  

National Technical Information Service (NTIS)

Although irradiation has been associated with deleterious effects on preserved bone graft in animals in the past, no report has suggested improvement in graft healing. The decrease in immunogenicity of frozen specimens associated with irradiation is not s...

S. Pellet D. M. Strong A. Temesi J. G. Matthews

1983-01-01

336

Prototype Acoustic Battlefield Decision Aid Incorporating Atmospheric Effects and Arbitrary Sensor Layouts.  

National Technical Information Service (NTIS)

The Acoustic Battlefield Aid (ABFA) is a prototype decision aid for assessing the performance of acoustic sensors in different environments. ABFA combines accurate modeling of atmospheric effects on acoustic signals with newly developed methods for determ...

K. Wilson

1998-01-01

337

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

338

Geostatistical Mapping of Mountain Precipitation Incorporating Autosearched Effects of Terrain and Climatic Characteristics  

Microsoft Academic Search

Hydrologic and ecologic studies in mountainous terrain are sensitive to the temporal and spatial distri- bution of precipitation. In this study a geostatistical model, Auto-Searched Orographic and Atmospheric Effects Detrended Kriging (ASOADeK), is introduced to map mountain precipitation using only precipi- tation gauge data. The ASOADeK model considers both precipitation spatial covariance and orographic and atmospheric effects in estimating precipitation

Huade Guan; John L. Wilson; Oleg Makhnin

2005-01-01

339

Incorporating a hybrid urease-carbon nanotubes sensitive nanofilm on capacitive field-effect sensors for urea detection.  

PubMed

The ideal combination among biomolecules and nanomaterials is the key for reaching biosensing units with high sensitivity. The challenge, however, is to find out a stable and sensitive film architecture that can be incorporated on the sensor's surface. In this paper, we report on the benefits of incorporating a layer-by-layer (LbL) nanofilm of polyamidoamine (PAMAM) dendrimer and carbon nanotubes (CNTs) on capacitive electrolyte-insulator-semiconductor (EIS) field-effect sensors for detecting urea. Three sensor arrangements were studied in order to investigate the adequate film architecture, involving the LbL film with the enzyme urease: (i) urease immobilized directly onto a bare EIS [EIS-urease] sensor; (ii) urease atop the LbL film over the EIS [EIS-(PAMAM/CNT)-urease] sensor; and (iii) urease sandwiched between the LbL film and another CNT layer [EIS-(PAMAM/CNT)-urease-CNT]. The surface morphology of all three urea-based EIS biosensors was investigated by atomic force microscopy (AFM), while the biosensing abilities were studied by means of capacitance-voltage (C/V) and dynamic constant-capacitance (ConCap) measureaments at urea concentrations ranging from 0.1 mM to 100 mM. The EIS-urease and EIS-(PAMAM/CNT)-urease sensors showed similar sensitivity (?18 mV/decade) and a nonregular signal behavior as the urea concentration increased. On the other hand, the EIS-(PAMAM/CNT)-urease-CNT sensor exhibited a superior output signal performance and higher sensitivity of about 33 mV/decade. The presence of the additional CNT layer was decisive to achieve a urea based EIS sensor with enhanced properties. Such sensitive architecture demonstrates that the incorporation of an adequate hybrid enzyme-nanofilm as sensing unit opens new prospects for biosensing applications using the field-effect sensor platform. PMID:24814256

Siqueira, José R; Molinnus, Denise; Beging, Stefan; Schöning, Michael J

2014-06-01

340

The effects of hyaluronic acid incorporated as a wetting agent on lysozyme denaturation in model contact lens materials.  

PubMed

Conventional and silicone hydrogels as models for contact lenses were prepared to determine the effect of the presence of hyaluronic acid on lysozyme sorption and denaturation. Hyaluronic acid was loaded into poly(2-hydroxyethyl methacrylate) and poly(2-hydroxyethyl methacrylate)/TRIS--methacryloxypropyltris (trimethylsiloxy silane) hydrogels, which served as models for conventional and silicone hydrogel contact lens materials. The hyaluronic acid was cross-linked using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide in the presence of dendrimers. Active lysozyme was quantified using a Micrococcus lysodeikticus assay while total lysozyme was determined using 125-I radiolabeled protein. To examine the location of hyaluronic acid in the gels, 6-aminofluorescein labeled hyaluronic acid was incorporated into the gels using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide chemistry and the gels were examined using confocal laser scanning microscopy. Hyaluronic acid incorporation significantly reduced lysozyme sorption in poly(2-hydroxyethyl methacrylate) (p?incorporated as a wetting agent has the potential to reduce lysozyme sorption and denaturation in contact lens applications. The distribution of hyaluronic acid within hydrogels appears to affect denaturation, with more surface mobile, lower molecular weight hyaluronic acid being more effective in preventing denaturation. PMID:22561981

Weeks, Andrea; Boone, Adrienne; Luensmann, Doerte; Jones, Lyndon; Sheardown, Heather

2013-09-01

341

The art and science of incorporating cost effectiveness into evidence-based recommendations for clinical preventive services.  

PubMed

As medical technology continues to expand and the cost of using all effective clinical services exceeds available resources, decisions about health care delivery may increasingly rely on assessing the cost-effectiveness of medical services. Cost-effectiveness is particularly relevant for decisions about how to implement preventive services, because these decisions typically represent major investments in the future health of large populations. As such, decisions regarding the implementation of preventive services frequently involve, implicitly if not explicitly, consideration of costs. Cost-effectiveness analysis summarizes the expected benefits, harms, and costs of alternative strategies to improve health and has become an important tool for explicitly incorporating economic considerations into clinical decision making. Acknowledging the usefulness of this tool, the third U.S. Preventive Services Task Force (USPSTF) has initiated a process for systematically reviewing cost-effectiveness analyses as an aid in making recommendations about clinical preventive services. In this paper, we provide an overview and examples of roles for using cost-effectiveness analyses to inform preventive services recommendations, discuss limitations of cost-effectiveness data in shaping evidence-based preventive health care policies, outline the USPSTF approach to using cost-effectiveness analyses, and discuss the methods the USPSTF is developing to assess the quality and results of cost-effectiveness studies. While this paper focuses on clinical preventive services (i.e., screening, counseling, immunizations, and chemoprevention), the framework we have developed should be broadly portable to other health care services. PMID:11306230

Saha, S; Hoerger, T J; Pignone, M P; Teutsch, S M; Helfand, M; Mandelblatt, J S

2001-04-01

342

Amplified electrokinetic response by concentration polarization near nanofluidic channel.  

PubMed

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 toward 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 nonuniform 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. PMID:19358584

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

2009-07-01

343

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

344

Quantitative structure-retention (property) relationships in micellar electrokinetic chromatography.  

PubMed

Quantitative structure-retention relationships (QSRRs) attempt to quantitatively understand the relationship between structure and retention and quantitative structure-property relationships (QSPRs) to explore the prediction of molecular properties from retention in chromatography. The application of these techniques to micellar electrokinetic chromatography (MEKC) and microemulsion electrokinetic chromatography (MEEKC) using surfactants, vesicles and liposomes is reviewed. A database of system constants for the solvation parameter model is assembled and critically discussed with respect to the interpretation of solvation properties of micellar pseudophases and their use to identify correlation models for the estimation of physicochemical and environmental properties from retention in MEKC and MEEKC. The use of structure-generated descriptors to model retention in MEKC is discussed and compared with experimental-based techniques. It is shown that the possibilities of exploiting the collection of tools that underpin QSRRs and QSPRs studies are only just starting to be realized in MEKC and more work is needed to convert from these possibilities to the realization of reliable and robust models for compounds of diverse structure. PMID:18207156

Poole, Salwa K; Poole, Colin F

2008-02-22

345

Electrokinetic shape changes of cochlear outer hair cells  

NASA Astrophysics Data System (ADS)

Rapid mechanical changes have been associated with electrical activity in a variety of non-muscle excitable cells1-5. Recently, mechanical changes have been reported in cochlear hair cells6-8. Here we describe electrically evoked mechanical changes in isolated cochlear outer hair cells (OHCs) with characteristics which suggest that direct electrokinetic phenomena are implicated in the response. OHCs make up one of two mechanosensitive hair cell populations in the mammalian cochlea; their role may be to modulate the micromechanical properties of the hearing organ through mechanical feedback mechanisms6-10. In the experiments described here, we applied sinusoidally modulated electrical potentials across isolated OHCs; this produced oscillatory elongation and shortening of the cells and oscillatory displacements of intracellular organdies. The movements were a function of the direction and strength of the electrical field, were inversely related to the ionic concentration of the medium, and occurred in the presence of metabolic uncouplers. The cylindrical shape of the OHCs and the presence of a system of membranes within the cytoplasm-laminated cisternae11-may provide the anatomical substrate for electrokinetic phenomena such as electro-osmosis12,13.

Kachar, Bechara; Brownell, William E.; Altschuler, Richard; Fex, Jörgen

1986-07-01

346

Electrokinetics Enhanced Delivery of Nano-scale Zero Valent Iron  

NASA Astrophysics Data System (ADS)

Nano-scale zero valent iron (NZVI) has shown promising results for remediation of a wide range of chlorinated hydrocarbons in the subsurface. Although rapid aggregation and subsequent sedimentation limit bare NZVI migration in subsurface systems, surface modifications have improved the colloidal stability of NZVI, enhancing NZVI migration through porous media in lab-scale experiments. However, delivery of NZVI through low permeability soil is still an unresolved challenge. Electrokinetics (EK) has been used extensively in low permeability porous media for the remediation of a variety of hazardous wastes and in particular heavy metals. Since NZVI has a net negative surface charge electrokinetics has been proposed to enhance NZVI transport in the subsurface. However, increased dissolved oxygen and lower pH, due to electrolysis of water at the anode, oxidizes Fe0 particles to Fe2+/Fe3+ and thus affects the remediation potential. This study focuses on minimization of NZVI oxidation and quantification of NZVI migration enhancement due to the EK application. Application of 50 and 100 mA currents delivered 6.0 and 4.8 times more NZVI through coarse sand, respectively, when compared to no EK application. This ratio increased to 21 and 31 at 50 and 100 mA currents when finer sand was used. In addition, a numerical model based on traditional colloidal filtration theory (CFT) fit the experimental results well.

Chowdhury, A. I.; O'Carroll, D. M.; Xu, Y.; Sleep, B. E.

2010-12-01

347

Numerical simulation of electrokinetic potentials associated with subsurface fluid flow  

NASA Astrophysics Data System (ADS)

A postprocessor has been developed to calculate space/time distributions of electrokinetic potentials resulting from histories of underground conditions (pressure, temperature, vapor saturation, concentrations of dissolved species, flow rate, etc.) computed by unsteady multidimensional geothermal reservoir simulations. Electrokinetic coupling coefficients are computed by the postprocessor using formulations based on experimental work reported by Ishido and Mizutani [1981]. The postprocessor was applied to both numerical modeling of natural self-potential (SP) anomalies in geothermal fields and production-induced SP changes. The essential features of the SP anomalies and SP changes which have actually been observed in real geothermal fields are reproduced reasonably well in these calculations for both single-phase (liquid) and two-phase (vapor/liquid) geothermal reservoirs. The postprocessor was also applied to predicting the magnitude of electrical earthquake precursory signals caused by dilatant strains taking place within a narrow vertical fault zone. If the rate of porosity increase is high enough to induce substantial pore pressure decrease, two-phase flow develops in the fault zone and produces observable signals at the ground surface if a high conductivity channel connects the near-surface region and the deep fault zone.

Ishido, Tsuneo; Pritchett, John W.

1999-07-01

348

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 (-10 kV, 20 s) was introduced in this MEEKC system and this yielded about 25-fold sensitivity enhancement compared with hydrodynamic injection (1 psi, 10 s). During method validation, calibration curves were linear (r?0.99), within a range of 75-500 ng/mL for DBP and 150-1000 ng/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 453.67 ng/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

2013-12-15

349

Electrokinetic potentials of clay surfaces modified by polymers  

SciTech Connect

This paper describes the influence of two polymers, fulvic acid (FA) and polyacrylic acids (PAAs) of comparable molecular mass, on the electrokinetic potential of model surfaces encountered in clay minerals: silica (SiO{sub 2}), aluminum oxide ({gamma}-Al{sub 2}O{sub 3}), and gibbsite [{gamma}-Al(OH){sub 3}]. Measurements at pH 6.5 {+-} 0.2 show that FA and PAAs modify the potentials of aluminum oxide and gibbsite, but leave the silica surface unchanged. A chlorite clay mineral (ripidolite), milled to increase the numbers of oxy-hydroxy groups at newly created surfaces, was exposed to FA and PAAs, carriers of carboxylic groups, to study their influence on electrokinetic potential. The key to the interaction is that polymers hold metal ions (Al, Mg, Fe) in the edge surfaces, while siloxane groups show limited interaction or none at all. The results offer an explanation of why clay mineral particles are always negatively charged in natural waters.

Sondi, I.; Pravdic, V. [Ruder Boskovic Inst., Zagreb (Croatia). Center for Marine Research] [Ruder Boskovic Inst., Zagreb (Croatia). Center for Marine Research; Milat, O. [Inst. of Physics, Zagreb (Croatia)] [Inst. of Physics, Zagreb (Croatia)

1997-05-01

350

Importance of Electrokinetic Phenomena in Contamination Control during Semiconductor Wet Processing.  

NASA Astrophysics Data System (ADS)

The adsorption of metanil yellow (3- {{4-(phenylamino) phenyl }azo} benzene sulfonate) and colloidal silica on a commercially available, positively charge-modified nylon 66 membrane (N66 Posidyne) with an isoelectric point (IEP) of 7.6 was investigated. Challenge testing of N66 Posidyne with a 2.3 ppm colloidal silica dispersion has shown that the membrane adsorbed 0.015 mug of colloidal silica per cm ^2. At a pH of 5.1, the adsorption of metanil yellow was found to increase with its solution concentration and reached a saturation value of 2.2 times 10^{14} ions/cm ^2 at a solution concentration of 1.49 times 10^{ -5}M. A technique to incorporate positively charged groups onto the surface of microporous polypropylene and polyvinylidene fluoride membrane filters for the filtration of liquids used in the semiconductor industry has been developed using gamma-irradiation. The electrical characteristics of prepared membranes were measured by streaming potential and dye challenge tests. The compatibility of these charge-modified membranes with ultrapure water was investigated. Results show that these charge-modified membranes are characterized by a positive zeta potential in the pH range from 4 to 9.3. From the dye challenge tests at a pH of 5.0, the density of positively charged sites on charge-modified membranes was calculated to be approximately five times larger than that of unmodified membranes. The modified membranes released less than 1 ppb of total organic carbon (TOC) into ultrapure water and thus appear to have potential for use in DI water system. The electrokinetic characteristics of silicon, silicon dioxide and silicon nitride wafers subjected to different cleaning procedures were measured using a streaming potential technique. A streaming potential cell for handling 5^{''} wafers was designed and fabricated to make these measurements. The isoelectric point of silicon, silicon dioxide and silicon nitride was dependent on the cleaning method. Polystyrene latex (PSL) and aminopropyl/silica particle deposition from aqueous solutions onto silicon nitride was investigated and correlated with the electrokinetic potential data.

Jan, Der-E.

351

Photon assisted growth of nitrogen-doped CdTe and the effects of hydrogen incorporation during growth  

NASA Astrophysics Data System (ADS)

Nitrogen doping in CdTe epilayers grown by photo-assisted molecular beam epitaxy was demonstrated using an rf plasma source. The effect of the presence of atomic hydrogen during growth of undoped and nitrogen-doped CdTe was investigated. The layers were characterized using photoluminescence spectros-copy (PL), Hall effect, secondary ion mass spectroscopy (SIMS), Fourier transform infrared spectroscopy, and atomic force microscopy. PL confirmed the incorporation of nitrogen as acceptors. While p-type carrier concentrations greater than 1018 cm-3 were easily obtained, SIMS measurements indicated that nitrogen was concentrated near the undoped-doped and epilayer-substrate interfaces which complicates interpretation of activation efficiency. Hydrogen incorporation was found to be enhanced by the presence of nitrogen. Infrared absorption measurements strongly suggested the formation of N-H complexes. Hall measurements indicated that complexes are formed which are donor-like in nature. The presence of atomic hydrogen during growth radically changed the low temperature photoluminescence in both undoped and nitrogen-doped layers. Exciton-related luminescence was quenched at low temperature. Nitrogenrelated donor-acceptor pair luminescence was also absent from the N-doped hydrogenated layers, consistent with complex formation. Copper (a cation-site acceptor) donor-acceptor pair luminescence appeared to be enhanced by hydrogenation.

Yu, Zhonghai; Buczkowski, S. L.; Petcu, M. C.; Giles, N. C.; Myers, T. H.; Richards-Babb, M.

1996-08-01

352

Creating a Ripple Effect: Incorporating Multimedia-Assisted Project-Based Learning in Teacher Education  

ERIC Educational Resources Information Center

This article explores the effects of multimedia-assisted, project-based learning in teacher education. We conducted pre- and post-surveys to investigate how the experience of developing multimedia projects influenced preservice teachers' knowledge and self-efficacy in (a) technology, (b) subject matter, and (c) teaching. Forty-two preservice…

Seo, Kay Kyeongju; Templeton, Rosalyn; Pellegrino, Debra

2008-01-01

353

A Measure of the Effectiveness of Incorporating 3D Human Anatomy into an Online Undergraduate Laboratory  

ERIC Educational Resources Information Center

Results of a study designed to determine the effectiveness of implementing three-dimensional (3D) stereo images of a human skull in an undergraduate human anatomy online laboratory were gathered and analysed. Mental model theory and its applications to 3D relationships are discussed along with the research results. Quantitative results on 62 pairs…

Hilbelink, Amy J.

2009-01-01

354

Competition Between Egress Transport Modes: Stated Choice Model Incorporating Availability Effects  

Microsoft Academic Search

This paper describes the results of a stated choice experiment that was conducted to understand better the substitution and synergy effects among various options for egress transport modes. The stated choice experiment that was designed varies the availability of alternative transport modes and makes it possible to identify which modes compete for the same market share. The survey consisted of

Eric J E Molin; Diana M VonkNoordegraaf; Fieke Mol; Harry J P Timmermans

2006-01-01

355

Ramp-rate limits in unit commitment and economic dispatch incorporating rotor fatigue effect  

Microsoft Academic Search

In this study, a rigorous mathematical method is proposed for dealing with the ramp-rate limits in unit commitment and the rotor fatigue effect in economic dispatch. An iterative procedure is employed to coordinate the unit commitment and the power dispatch for obtaining an economical solution within a reasonable time. The Lagrangian relaxation method is used to generate the unit commitment

C. Wang; S. M. Shahidehpour

1994-01-01

356

Herbicidal effects of extracts and residue incorporation of Datura metel against parthenium weed  

Microsoft Academic Search

The present study was designed to evaluate the herbicidal activity of Datura metel against the noxious weed parthenium (Parthenium hysterophorus L.). In a laboratory bioassay, the effect of aqueous, methanol and n-hexane shoot and root extracts of 5, 10, 15 and 20% w\\/v (on a fresh weight basis) concentration of D. metel were tested against the germination and seedling growth

Arshad Javaid; Sobiya Shafique; Shazia Shafique

2010-01-01

357

Sustained antibacterial effect of a hand rub gel incorporating chlorhexdine-loaded nanocapsules (Nanochlorex).  

PubMed

In the present study, an original chlorhexidine-loaded nanocapsule-based gel (Nanochlorex) was tested as hand rub gel against the resident skin flora in comparison with 2-propanol 60% (v/v) and 62% (v/v) ethanol-based gel (Purell). After 30-s hand rub, the immediate bactericidal effect of Nanochlorex was found comparable to 2-propanol 60% (v/v) (reduction factor, RF: 0.30+/-0.35 versus 0.38+/-0.55, P>0.05) against aerobic bacteria, whereas the post-values of surviving anaerobes were shown significantly lower from Nanochlorex (P<0.001) and insignificant from 2-propanol 60% (v/v) (P>0.05). Sustained antibacterial effect of Nanochlorex was confirmed against the resident and transient hand flora in two sets of experiment. In the first, the results obtained with the glove-juice technique showed that the bactericidal effect induced by Nanochlorex hand rub persisted throughout 3-h period, while Purell failed to reduce significantly the post-values of surviving bacteria. In the second, repeated artificial contaminations with Staphylococcus epidermidis was carried out onto ex vivo human skin pre-treated by either Nanochlorex or Purell for 5min, then maintained in cell diffusion apparatus for 4h. The log(10) reduction of surviving bacteria was significantly higher with Nanochlorex than that determined with Purell after three successive contaminations (from approximately 5.5 to 1.5 log(10) reduction for Nanochlorex between the first and the third contamination; approximately 1log(10) reduction for Purell throughout the experiment), confirming the sustained antibacterial effect of chlorhexidine-loaded nanocapsule-based gel. The immediate and sustained antibacterial effect of Nanochlorex was explained by chlorhexidine carrier system which improved the drug targeting to bacteria and reduced from osmotic gel further bacterial growth on the skin. Nanochlorex) might constitute a promising approach for hygienic hand disinfection in care practice performing multiple procedures. PMID:17113253

Nhung, Dang Thi Tuyet; Freydiere, Anne-Marie; Constant, Hélène; Falson, Françoise; Pirot, Fabrice

2007-04-01

358

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

359

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

360

Effects of Processing on Nutritional and Sensory Qualities of Beef Burgers Incorporated With Palm Fats  

Microsoft Academic Search

A study was undertaken to investigate the effects of processing on the nutritional and sensory qualities of beef burgers formulated with palm fats as animal fat analogues. After processing, a-tocopherol and a-tocotrienol levels were significantly decreased, ranging from 46-48% to 36-44% respectively, in beef burgers made with red palm fat (RPF35) and fat blend. The changes in the levels of

Wan Rosli WI; Babji AS; Aminah A; Foo SP; Abd Malik O

361

Reducing effect of softball-to-head impact by incorporating slip-surface in helmet  

Microsoft Academic Search

In this study we explore the effect of head-helmet interaction, in an effort to better understand the contributing factors that lead to mild traumatic brain injury (MTBI). A Hybrid III anthropomorphic head-form, fit with a Major League Baseball (MLB) approved helmet, was laterally struck with a softball at the center of gravity (CG), at 50.8mm above the CG, and at

Matthew B. Robinson; Tyler Stousland; Muhammad Baqui; Ghodrat Karami; Mariusz Ziejewski

2011-01-01

362

Memory effects in metal-oxide-semiconductor capacitors incorporating dispensed highly monodisperse 1 nm silicon nanoparticles  

Microsoft Academic Search

Metal-oxide-semiconductor capacitors containing various densities of ex situ produced, colloidal, highly monodisperse, spherical, 1 nm silicon nanoparticles were fabricated and evaluated for potential use as charge storage elements in future nonvolatile memory devices. The capacitance-voltage characteristics are well behaved and agree with similarly fabricated zero-nanoparticle control samples and with an ideal simulation. Unlike larger particle systems, the demonstrated memory effect

Osama M. Nayfeh; Dimitri A. Antoniadis; Kevin Mantey; Munir H. Nayfeh

2007-01-01

363

Effect of antimony incorporation on structural properties of CuInS 2 crystals  

Microsoft Academic Search

CuInS2 (CIS) single crystals doped with 1, 2, 3 and 4 atomic percent (at.%) of antimony (Sb) were grown by the horizontal Bridgman method. The effect of Sb doping on the structural properties of CIS crystal was studied by means of X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and PL measurements. X-ray diffraction data suggests

M. Ben Rabeh; N. Chaglabou; M. Kanzari

2010-01-01

364

Promotion and computation of inhibitory effect on tyrosinase activity of herbal cream by incorporating indigenous medicinal plants.  

PubMed

Herbal cream imparts a chief role in regulating melanin production of skin. The phytoconstituents present in herbal cream impact biological functions of skin and contribute nutrients required for the healthy skin. In the present study, it was envisaged to prepare three batches of herbal cream (HC1, HC2 and HC3) containing ethanol extracts of Emblica officinalis (fruits), Daucus carota (root), Mangifera indica (leaves), Mentha arvensis (leaves), Terminalia arjuna (bark) and Cucumis sativus (fruits) and investigated the prepared cream for inhibitory effect on tyrosinase activity. The herbal cream was formulated by incorporating different ratio of extracts, by using cream base. Each formulation HC1, HC2 and HC3 were segregated into three different formulations (HC1.1, HC1.2, HC1.3, HC2.1, HC2.2, HC2.3, HC3.1, HC3.2 and HC3.3) by incorporating increasing ratio of extract in formulation. The HC3.2 cream produces highest tyrosinase inhibitory effect 65.23 +/- 0.07%, while the HC2.1 exhibited minimum tyrosinase inhibitory effect 26.19 +/- 0.08% compared to other prepared cream. Comparison of the inhibitory activity of the formulations demonstrated that the rank order was HC3.2 > HC3.3 > HC1.2 > HC1.3 > HC3.1 > HC1.1 > HC2.3 > HC2.2 > HC2.1. It has been observed from the result that the formulations of antityrosinase activity were not concentrate dependent. This finding suggests that decrease in antityrosinase activity of HC1 and HC3 might be considering that the incompatibility of the higher extract content with the base of cream. The HC3 produce the maximum inhibitory effects on tyrosinase activity might be due to higher level of polyphenol and flavonoids present in extracts. PMID:24783796

Sahu, Ram Kumar; Roy, Amit; Dwivedi, Jaya; Jha, Arvind Kumar

2014-01-01

365

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 ...

366

MICELLAR ELECTROKINETIC CHROMATOGRAPHY: A NEW TOOL FOR FIELD SCREENING OF SEMIVOLATILES  

EPA Science Inventory

Capillary electrophoresis (CE) and the related techniques of micellar electrokinetic chromatography (MEKC) are relatively new to environmental analysis. E is better known in the biomedical and pharmaceutical fields where it is employed for protein and drug separations, respective...

367

Effect of combined treatment with the epirubicin-incorporating micelles (NC-6300) and 1,2-diaminocyclohexane platinum (II)-incorporating micelles (NC-4016) on a human gastric cancer model.  

PubMed

Anticancer agent-incorporating polymeric micelles accumulate effectively in tumors via the enhanced permeability and retention effect to exert potent antitumor effects. However, combined use of such micelles has not been elucidated. We compared the effect of combining the epirubicin-incorporating micelle NC-6300 and 1,2-diaminocyclohexane platinum (II) (oxaliplatin parent complex)-incorporating micelle NC-4016 (NCs) with that of epirubicin and oxaliplatin (E/O) in 44As3Luc cells using the combination index method. The in vivo antitumor activities of NCs and E/O were evaluated in mice bearing 44As3Luc xenografts. Pharmacokinetic analysis was performed by high-performance liquid chromatography and mass spectrometry. Cardiotoxicity of NC-6300 and epirubicin was assessed by echocardiography. Neurotoxicity of NC-4016 and oxaliplatin was evaluated by examining the paw withdrawal response to noxious mechanical stimuli. NCs showed a highly synergistic activity equivalent to E/O. In vivo, NCs exhibited higher antitumor activity in the subcutaneous tumor model and longer overall survival in the orthotopic tumor model than E/O (p?

Yamamoto, Yoshiyuki; Hyodo, Ichinosuke; Takigahira, Misato; Koga, Yoshikatsu; Yasunaga, Masahiro; Harada, Mitsunori; Hayashi, Tatsuyuki; Kato, Yasuki; Matsumura, Yasuhiro

2014-07-01

368

Effect of nitrogen incorporation on electrical properties of Ti/Au/GaAsN Schottky diodes  

NASA Astrophysics Data System (ADS)

Electrical I-V and C-V-F measurements have used to investigate the behaviour of Ti/Au/GaAsN Schottky diodes, deposited by Molecular Beam Epitaxy, with various nitrogen percent contents. Ideality factor and series resistance were found to increase with increasing N% dilution in GaAs. This was accompanied by a decrease in Schottky barrier height (I-V). The discrepancy found between Schottky barrier heights estimated from I-V and C-V measurements is attributed to a difference in measurements methods and inhomogeneities in barrier height. The peak capacitance behaviour and its dependence on frequency for Schottky diodes with 0.8% N and 1.2% N content was attributed to annihilation of trap levels below midgap. These traps levels associated with those above midgap are responsible for the nondependence of peak capacitance on frequency for Schottky diodes with 0.2% N content. A compensation effect between traps below and above midgap is believed to be taking place. The dependency reappears for Schottky diodes without nitrogen content and is attributed to trap levels below midgap. Capacitance and conductance at high frequency were corrected to eliminate series resistance effect. Interface states density significantly increased when we increased dilute nitride concentration and may play an important role in Ti/Au/GaAsN Schottky diodes at low frequency.

Bachir Bouiadjra, Wadi; Saidane, Abdelkader; Mostefa, Abdelkader; Henini, Mohamed; Shafi, M.

2014-07-01

369

Separation and analysis of cis-diol-containing compounds by boronate affinity-assisted micellar electrokinetic chromatography.  

PubMed

Cis-diol-containing compounds (CDCCs) are usually highly hydrophilic compounds and are therefore difficult to separate by conventional reversed-phase-based micellar electrokinetic chromatography (MEKC) due to poor selectivity. Here, we report a new method, called boronate affinity-assisted micellar electrokinetic chromatography (BAA-MEKC), to solve this issue. A boronic acid with a hydrophobic alkyl chain was added to the background electrolyte, which acted as a modifier to adjust the selectivity. CDCCs can covalently react with the boronic acid to form negatively charged surfactant-like complexes, which can partition into micelles formed with a cationic surfactant. Thus, CDCCs can be separated according to the differential partition constants of their boronic acid complexes between the micellar phase and the surrounding aqueous phase. To verify this method, eight nucleosides were employed as the test compounds and their separation confirmed that the combination of boronate affinity interaction with MEKC can effectively enhance the separation of CDCCs. The effects of experimental conditions on the separation were investigated. Finally, the BAA-MEKC method was applied to the separation and analysis of nucleosides extracted from human urine. BAA-MEKC exhibited better selectivity and improved separation as compared with conventional MEKC and CZE. Successful quantitative analysis of urinary nucleosides by BAA-MEKC was demonstrated. PMID:23907689

Wang, Heye; Lü, Chenchen; Li, Hengye; Chen, Yang; Zhou, Min; Ouyang, Jian; Liu, Zhen

2013-10-01

370

Effect of multi-walled carbon nanotubes incorporation into benzyl methacrylate monolithic columns in capillary liquid chromatography.  

PubMed

This work describes the preparation of polymer based monolithic materials and their use as stationary phases in capillary liquid chromatography. Multi-walled carbon nanotubes (MWCNT) were incorporated into a mixture containing benzyl methacrylate (BMA) and ethylene dimethacrylate (EDMA) as co-monomers. The optimized porogenic mixture was a ternary solution composed of cyclohexanol, 1,4-butandiol and butanol which resulted in a stable and homogeneous suspension. Six capillary columns with increasing amounts of MWCNT, from 0 to 0.4 mg mL(-1), were prepared by thermal polymerization in 0.32 mm (i.d.) and 150 mm length fused silica tubing. The chromatographic evaluation showed that the synthesized monolithic beds were mechanically stable while their porosity and permeability increased with the MWCNT content. The prepared capillary columns were tested for the separation of mixtures of ketones and phenols at an optimum flow rate of 2 ?L min(-1). The results showed that incorporation of MWCNT slightly affected the retention while it enhanced the column efficiency by increasing the column efficiency by a factor of up to 9. This effect corresponded also to an improved resolution and full separation of the solutes. PMID:22847179

Aqel, Ahmad; Yusuf, Kareem; Al-Othman, Zeid A; Badjah-Hadj-Ahmed, A Yacine; Alwarthan, Abdulrahman A

2012-09-21

371

Confinement Effects on the Dynamic Behavior of Poly(d,l-lactic Acid) upon Incorporation in ?-Cyclodextrin.  

PubMed

Inclusion complexes (ICs) composed of ?-cyclodextrin (?-CD) and poly(d,l-lactic acid) (PDLLA), with 10/24 (IC1) and 15/46 (IC2) (% w/w) of PDLLA incorporated/initial PDLLA weight percentage, were prepared and characterized mainly by dielectric relaxation spectroscopy (DRS). Bulk PDLLA was also analyzed for comparison. DRS was revealed to be a suitable tool to distinguish the dynamical response of the PDLLA regions constrained in between ?-CD channels from the fraction incorporated inside channels. While the cooperative ?-process undergoes a dramatic depletion shifting to higher temperatures (?4.5 °C) for the PDLLA interchannels portion, it is suppressed for PDLLA chains inside pores. It was demonstrated that the broad secondary relaxation of bulk PDLLA is the Johari-Goldstein process (?JG-process). The detection of its analogue in the ICs at higher frequencies, to a greater extent in IC1, is interpreted as a true confinement effect where the dimensions of the ?-CD channels interfere with the length scale of the ?JG-process. The limit predicted in the framework of the coupling model, where the ?-relaxation transforms in the ?JG-process, seems to be reached in the ICs. Furthermore, it was found that the length scale of the additional ? process only detected in the ICs is inferior to inter- or intrachannel dimensions. PMID:24899144

Viciosa, M T; Alves, N M; Oliveira, T; Dionísio, M; Mano, J F

2014-06-19

372

The effects of iron oxide incorporation on the chondrogenic potential of three human cell types.  

PubMed

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. PMID:22396122

Saha, Sushmita; Yang, Xuebin B; Tanner, Steven; Curran, Stephen; Wood, David; Kirkham, Jennifer

2013-06-01

373

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

374

Recent progress in the development, characterization and application of polymeric pseudophases for electrokinetic chromatography.  

PubMed

This review article details the development, characterization and application of polymeric materials as pseudostationary phases for electrokinetic chromatography over the past two years. Recent developments in cationic polymers and anionic siloxane, acrylamide and polymerized surfactants (micelle polymers) are reviewed. Also reviewed is recent progress in the development and characterization of chiral polymeric phases for chiral separations by electrokinetic chromatography, and application of a polymeric pseudophase with electrospray ionization mass spectrometric detection. PMID:12481289

Palmer, Christopher P

2002-11-01

375

Characterization of anacardic acids by micellar electrokinetic chromatography and mass spectrometry  

Microsoft Academic Search

A possibility of using capillary electrophoresis for separation of anacardic acids (6-alkylsalicylic acids) has been studied. Conventional micellar electrokinetic chromatography (MEKC) in non-coated fused silica capillaries and reversed-flow micellar electrokinetic chromatography (RF-MEKC) in capillaries coated with polydimethylacrylamide was applied for separation of anacardic acids extracted from cashew nuts. Influence of the composition of background electrolyte on the resolution of anacardic

Petr ?esla; Lars Blomberg; Mats Hamberg; Pavel Jandera

2006-01-01

376

Effectiveness of chitosan-coated plastic films incorporating antimicrobials in inhibition of Listeria monocytogenes on cold-smoked salmon.  

PubMed

The objective of this study was to evaluate the efficacy of chitosan-coated plastic films incorporating five Generally Recognized as Safe (GRAS) antimicrobials (nisin, sodium lactate (SL), sodium diacetate (SD), potassium sorbate (PS) and sodium benzoate (SB)) against Listeria monocytogenes on cold-smoked salmon. Salmon samples were surface-inoculated with a five-strain cocktail of L. monocytogenes and packaged in chitosan-coated plastic films containing 500 IU/cm(2) of nisin, 9 mg/cm(2) of SL, 0.5 mg/cm(2) of SD, 0.6 mg/cm(2) of PS, or 0.2 mg/cm(2) of SB, and stored at room temperature (ca. 20 degrees C) for 10 days. The film incorporating SL was the most effective, completely inhibiting the growth of L. monocytogenes during 10 days of storage. L. monocytogenes in samples packaged in the other four antimicrobial films grew, but the increase in counts was lower than the control. The antilisterial efficacy of films containing lower concentrations of SL (2.3 mg/cm(2) and 4.5 mg/cm(2)) and binary combinations SL, PS, SD, SB and nisin were subsequently evaluated. Among all the treatments, chitosan-coated plastic films with 4.5 mg/cm(2) SL, 4.5 mg/cm(2) SL-0.6 mg/cm(2) PS and 2.3 mg/cm(2) SL-500 IU/cm(2) nisin were the most effective. These three most effective antimicrobial films were then tested at refrigerated temperature. They completely inhibited the growth of L. monocytogenes on smoked salmon for at least 6 weeks. Chitosan-coated plastic films containing 4.5 mg/cm(2) SL can potentially assist the smoked-salmon processing industry in their efforts to control L. monocytogenes. PMID:18707789

Ye, Mu; Neetoo, Hudaa; Chen, Haiqiang

2008-10-31

377

Incorporating cumulative effects into environmental assessments of mariculture: Limitations and failures of current siting methods  

SciTech Connect

Assessing and evaluating the cumulative impacts of multiple marine aquaculture facilities has proved difficult in environmental assessment. A retrospective review of 23 existing mariculture farms in southwestern New Brunswick was conducted to determine whether cumulative interactions would have justified site approvals. Based on current scientific evidence of cumulative effects, six new criteria were added to a set of far-field impacts and other existing criteria were expanded to include regional and cumulative environmental impacts in Hargrave's [Hargrave BT. A traffic light decision system for marine finfish aquaculture siting. Ocean Coast Manag 2002; 45:215-35.] Traffic Light Decision Support System (DSS) presently used in Canadian aquaculture environmental assessments. Before mitigation, 19 of the 23 sites failed the amended set of criteria and after considering mitigation, 8 sites failed. Site and ecosystem indices yielded varying site acceptability scores; however, many sites would not have been approved if siting decisions had been made within a regional management framework and cumulative impact criteria were considered in the site evaluation process.

King, Sarah C. [Greenpeace Canada, 1726 Commercial Drive, Vancouver, B.C., V5N 4A3 (Canada)], E-mail: scoldwellking@hotmail.com; Pushchak, Ronald [School of Urban and Regional Planning, Ryerson University, 350 Victoria Street, Toronto, Ontario, M5B 2K3 (Canada)], E-mail: pushchak@ryerson.ca

2008-11-15

378

PCL films incorporated with paclitaxel/5-fluorouracil: Effects of formulation and spacial architecture on drug release.  

PubMed

The bi/tri-layered poly(?-caprolactone) (PCL)-based films co-loaded with 5-fluorouracil (5-FU) and paclitaxel (PTX) are presented for biodegradable film-based stent application. A gradient elution HPLC analytical method was used for simultaneous quantification of 5-FU and PTX. Scanning electron microscopy (SEM) was performed to observe the microscopic architecture and morphologies, and X-ray diffraction (XRD) was employed for analyzing the physical state of the components in the single layer film. Horizontal cells diffusion test results indicated that the multi-layered structure endowed the film with drug release in unidirectional pattern. The in vitro release results showed that drug release was dependent on the drug loading, the ratio of 5-FU/PTX, the composition of surface layer, as well as the addition of hydrophilic PEG. The cytotoxicity results indicated that the PCL-based films co-loaded with 5-FU and PTX could effectively inhibit the proliferation of Eca-109 cells. The in vivo drug release results showed that the in vivo drug release was highly correlative with the in vitro drug releases. This study provided PCL-based films co-loaded with 5-FU and PTX with great potential for anti-tumor stent application, due to their unidirectional and rate-tunable drug release characteristics and dual drug loading capacity. PMID:22349052

Rong, Hao-Jun; Chen, Wei-Luan; Guo, Sheng-Rong; Lei, Lei; Shen, Yuan-Yuan

2012-05-10

379

Optical spacing effect in organic photovoltaic cells incorporating a dilute acceptor layer  

NASA Astrophysics Data System (ADS)

The addition of spacing layers in organic photovoltaic cells (OPVs) can enhance light absorption by optimizing the spatial distribution of the incident optical field in the multilayer structure. We explore the optical spacing effect in OPVs achieved using a diluted electron acceptor layer of C60. While optical spacing is often realized by optimizing buffer layer thickness, we find that optical spacing via dilution leads to cells with similar or enhanced photocurrent. This is observed despite a smaller quantity of absorbing molecules, suggesting a more efficient use of absorbed photons. In fact, dilution is found to concentrate optical absorption near the electron donor-acceptor interface, resulting in a marked increase in the exciton diffusion efficiency. Contrasting the use of changes in thickness to engineer optical absorption, the use of dilution does not significantly alter the overall thickness of the OPV. Optical spacing via dilution is shown to be a viable alternative to more traditional optical spacing techniques and may be especially useful in the continued optimization of next-generation, tandem OPVs where it is important to minimize competition for optical absorption between individual sub-cells.

Menke, S. Matthew; Lindsay, Christopher D.; Holmes, Russell J.

2014-06-01

380

Effect of antimony incorporation on structural properties of CuInS 2 crystals  

NASA Astrophysics Data System (ADS)

CuInS 2 (CIS) single crystals doped with 1, 2, 3 and 4 atomic percent (at.%) of antimony (Sb) were grown by the horizontal Bridgman method. The effect of Sb doping on the structural properties of CIS crystal was studied by means of X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and PL measurements. X-ray diffraction data suggests that the doping of Sb in the CIS single crystals does not affect the tetragonal (chalcopyrite) crystal structure and exhibited a (1 1 2) preferred orientation. In addition, with increasing Sb concentration, the X-ray diffraction analysis show that Sb doped CIS crystals are more crystallized and the diffraction peaks of the CuInS 2 phase were more pronounced in particular the (1 1 2) plane. EDAX study revealed that Sb atoms can occupy the indium site and/or occupying the sulfur site to make an acceptor. PL spectra of undoped and Sb doped CIS crystals show two emission peaks at 1.52 and 1.62 eV, respectively which decreased with increasing atomic percent antimony. Sb doped CIS crystals show p-type conductivity.

Ben Rabeh, M.; Chaglabou, N.; Kanzari, M.

2010-02-01

381

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

382

Effects of incorporation of HA/ZrO(2) into glass ionomer cement (GIC).  

PubMed

Glass ionomer cements (GICs) are a class of bioactive cements that bond directly to bone. In this paper, a new bioactive hydroxyapatite (HA)/zirconia (ZrO(2))-filled GIC composite was developed to improve the biocompatibility and bioactivity of the GICs with the surrounding bone and connective tissues. Nano-sized HA/30 wt% ZrO(2) powders were heat treated at 700 degrees Celsius and 800 degrees Celsius for 3 h to elucidate the influence of the crystallinity of composite powders on the performance of HA/ZrO(2)-GICs. The effects of different volume percentages of HA/ZrO(2) powders (4, 12, 28 and 40 vol%) substituted within GICs were investigated based on their microhardness, compressive strength and diametral tensile strength. The HA/ZrO(2)-GICs composite was soaked in distilled water for 1 day and 1 week before subjecting the samples to mechanical testing. Results showed that the glass and HA/ZrO(2) particles were distributed uniformly in the GIC matrix. The substitution of highly crystalline HA/ZrO(2) improved the mechanical properties of the HA/ZrO(2)-GICs due to the slow resorption rate for highly crystalline powders in distilled water. The mechanical properties of HA/ZrO(2)-GICs increased with increasing soak time due to the continuous formation of aluminium salt bridges, which improved the final strength of the cements. The compositions 4 and 12 vol% HA/ZrO(2)-GICs exhibited superior mechanical properties than the original GICs. The mechanical properties of HA/ZrO(2)-GICs were found to be much better than those of HA-GICs because ZrO(2) has the attributes of high strength, high modulus, and is significantly harder than glass and HA particles. Furthermore, ZrO(2) does not dissolve with increasing soaking time. PMID:15350775

Gu, Y W; Yap, A U J; Cheang, P; Khor, K A

2005-03-01

383

Effect of phosphorus incorporation on morphology and optical properties of ZnO nanorods  

SciTech Connect

Graphical abstract: XPS spectra of the P-doped ZnO nanorods: (a) Zn 2p, (b) O 1s, and (c) P 2p spectra. The red curve in c is the Gauss-fitting curve. (d) Raman spectra of P-doped (curve 1) and pure (curve 2) ZnO nanorods. Research highlights: {yields} P-doped ZnO nanorods have been prepared on Si substrates without any catalyst. {yields} The introduction of phosphorus leads to the growth of tapered tip in the nanorods. {yields} The formation of tapered tip is attributed to the relaxation of the lattice strain along the radial direction. {yields} The strong ultraviolet peak is connected with the phosphorus acceptor-related emissions. -- Abstract: Phosphorus-doped ZnO nanorods have been prepared on Si substrates by thermal evaporation process without any catalyst. X-ray photoelectron spectroscopy and Raman spectra indicate that phosphorus entering into ZnO nanorods mainly occupies Zn site rather than O one. The introduction of phosphorus leads to the morphological changes of nanorods from hexagonal tip to tapered one, which should be attributed to the relaxation of the lattice strain caused by phosphorus occupying Zn site along the radial direction. Transmission electron microscopy shows that phosphorus-doped ZnO nanorods still are single crystal and grow along [0 0 0 1] direction. The effect of phosphorous dopant on optical properties of ZnO nanorods also is studied by the temperature-dependent photoluminescence spectra, which indicates that the strong ultraviolet emission is connected with the phosphorus acceptor-related emissions.

Fan, Donghua, E-mail: donghua_fan@126.com [School of Applied Physics and Materials, Wuyi University, Jiangmen 529020 (China)] [School of Applied Physics and Materials, Wuyi University, Jiangmen 529020 (China); Zhang, Rong [Department of Physics, Shanghai Maritime University, 1550 Pudong Avenue, Shanghai 200135 (China)] [Department of Physics, Shanghai Maritime University, 1550 Pudong Avenue, Shanghai 200135 (China); Wang, Xianghu [Shanghai Dianji University, Shanghai 200240 (China)] [Shanghai Dianji University, Shanghai 200240 (China)

2011-04-15

384

Effect of Sb incorporation on structure and magnetic properties of quaternary ferromagnetic semiconductor (Ga, Mn)(As, Sb) thin films  

NASA Astrophysics Data System (ADS)

GaAs-based quaternary ferromagnetic semiconductor (Ga, Mn)(As, Sb) has been successfully prepared by molecular-beam epitaxy. High-resolution x-ray diffraction measurements indicate that the lattice constant has a notable alteration with changing Sb content. Magnetic measurements demonstrate the same evolution of the Curie temperature TC and the effective Mn content xeff with increasing Sb content. The incorporation of low Sb content is of benefit to increasing xeff, thus, increasing TC. However, higher Sb content degrades the crystal quality, resulting in a decrease of xeff. Experimental results show that TC is proportional to the product of xeff and p1/3, which is consistent with the Zener Model. The exchange energy N0? is calculated to be -1.09 eV, which is similar to that of (Ga, Mn)As.

Deng, J. J.; Che, J. T.; Chen, J.; Wang, W. J.; Hu, B.; Wang, H. L.; Zhao, J. H.

2013-12-01

385

A stoichiometric producer-grazer model incorporating the effects of excess food-nutrient content on consumer dynamics.  

PubMed

There has been important progress in understanding ecological dynamics through the development of the theory of ecological stoichiometry. For example, modeling under this framework allows food quality to affect consumer dynamics. While the effects of nutrient deficiency on consumer growth are well understood, recent discoveries in ecological stoichiometry suggest that consumer dynamics are not only affected by insufficient food nutrient content (low phosphorus (P): carbon (C) ratio) but also by excess food nutrient content (high P:C). This phenomenon is known as the stoichiometric knife edge, in which animal growth is reduced not only by food with low P content but also by food with high P content, and needs to be incorporated into mathematical models. Here we present a Lotka-Volterra type model to investigate the growth response of Daphnia to algae of varying P:C ratios capturing the mechanism of the stoichiometric knife edge. PMID:23684950

Peace, Angela; Zhao, Yuqin; Loladze, Irakli; Elser, James J; Kuang, Yang

2013-08-01

386

A novel nano hydroxyapatite-incorporated Ni-P coating as an effective inter layer for biological applications.  

PubMed

Hydroxyapatite (HA) coatings are normally made directly on orthopaedic implants and they possess many demerits such as cracks, irregular phase composition and poor adhesion. The present study had a novel approach of providing a nano-HA and phosphorous-rich electroless nickel (EN) coating as an interlayer on stainless steel (SS) prior to electrodeposition of pure HA coating. The interlayer had the merits of having incorporated with nano HA with rich phosphorous content. The outermost HA coating had excellent adherence and it was found to be free from any defects since it was formed only on the interlayer and not on the direct substrate. The overall coating system revealed high bioactivity when immersed in simulated body fluid (SBF). The present study also highlights the scope of using cost effective SS as the implant substrate instead of titanium as against the current trend of substrate selection. PMID:18987947

Shibli, S M A; Jayalekshmi, A C

2009-03-01

387

Self-Consistent Approach to Global Charge Neutrality in Electrokinetics: A Surface Potential Trap Model  

NASA Astrophysics Data System (ADS)

In this work, we treat the Poisson-Nernst-Planck (PNP) equations as the basis for a consistent framework of the electrokinetic effects. The static limit of the PNP equations is shown to be the charge-conserving Poisson-Boltzmann (CCPB) equation, with guaranteed charge neutrality within the computational domain. We propose a surface potential trap model that attributes an energy cost to the interfacial charge dissociation. In conjunction with the CCPB, the surface potential trap can cause a surface-specific adsorbed charge layer ?. By defining a chemical potential ? that arises from the charge neutrality constraint, a reformulated CCPB can be reduced to the form of the Poisson-Boltzmann equation, whose prediction of the Debye screening layer profile is in excellent agreement with that of the Poisson-Boltzmann equation when the channel width is much larger than the Debye length. However, important differences emerge when the channel width is small, so the Debye screening layers from the opposite sides of the channel overlap with each other. In particular, the theory automatically yields a variation of ? that is generally known as the "charge regulation" behavior, attendant with predictions of force variation as a function of nanoscale separation between two charged surfaces that are in good agreement with the experiments, with no adjustable or additional parameters. We give a generalized definition of the ? potential that reflects the strength of the electrokinetic effect; its variations with the concentration of surface-specific and surface-nonspecific salt ions are shown to be in good agreement with the experiments. To delineate the behavior of the electro-osmotic (EO) effect, the coupled PNP and Navier-Stokes equations are solved numerically under an applied electric field tangential to the fluid-solid interface. The EO effect is shown to exhibit an intrinsic time dependence that is noninertial in its origin. Under a step-function applied electric field, a pulse of fluid flow is followed by relaxation to a new ion distribution, owing to the diffusive counter current. We have numerically evaluated the Onsager coefficients associated with the EO effect, L21, and its reverse streaming potential effect, L12, and show that L12=L21 in accordance with the Onsager relation. We conclude by noting some of the challenges ahead.

Wan, Li; Xu, Shixin; Liao, Maijia; Liu, Chun; Sheng, Ping

2014-01-01

388

Effectiveness of strategies incorporating training and support of traditional birth attendants on perinatal and maternal mortality: meta-analysis  

PubMed Central

Objective To assess the effectiveness of strategies incorporating training and support of traditional birth attendants on the outcomes of perinatal, neonatal, and maternal death in developing countries. Design Systematic review with meta-analysis. Data sources Medline, Embase, the Allied and Complementary Medicine database, British Nursing Index, Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, BioMed Central, PsycINFO, Latin American and Caribbean Health Sciences Literature database, African Index Medicus, Web of Science, Reproductive Health Library, and Science Citation Index (from inception to April 2011), without language restrictions. Search terms were “birth attend*”, “traditional midwife”, “lay birth attendant”, “dais”, and “comadronas”. Review methods We selected randomised and non-randomised controlled studies with outcomes of perinatal, neonatal, and maternal mortality. Two independent reviewers undertook data extraction. We pooled relative risks separately for the randomised and non-randomised controlled studies, using a random effects model. Results We identified six cluster randomised controlled trials (n=138?549) and seven non-randomised controlled studies (n=72?225) that investigated strategies incorporating training and support of traditional birth attendants. All six randomised controlled trials found a reduction in adverse perinatal outcomes; our meta-analysis showed significant reductions in perinatal death (relative risk 0.76, 95% confidence interval 0.64 to 0.88, P<0.001; number needed to treat 35, 24 to 70) and neonatal death (0.79, 0.69 to 0.88, P<0.001; 98, 66 to 170). Meta-analysis of the non-randomised studies also showed a significant reduction in perinatal mortality (0.70, 0.57 to 0.84, p<0.001; 48, 32 to 96) and neonatal mortality (0.61, 0.48 to 0.75, P<0.001; 96, 65 to 168). Six studies reported on maternal mortality and our meta-analysis showed a non-significant reduction (three randomised trials, relative risk 0.79, 0.53 to 1.05, P=0.12; three non-randomised studies, 0.80, 0.44 to 1.15, P=0.26). Conclusion Perinatal and neonatal deaths are significantly reduced with strategies incorporating training and support of traditional birth attendants.

2011-01-01

389

Effects of straw incorporation on soil organic matter and soil water-stable aggregates content in semiarid regions of Northwest China.  

PubMed

The soil degradation caused by conventional tillage in rain-fed areas of northwest China is known to reduce the water-use efficiency and crop yield because of reduced soil porosity and the decreased availability of soil water and nutrients. Thus, we investigated the effects of straw incorporation on soil aggregates with different straw incorporation rates in semiarid areas of southern Ningxia for a three-year period (2008-2010). Four treatments were tested: (i) no straw incorporation (CK); (ii) incorporation of maize straw at a low rate of 4 500 kg ha-1 (L); (iii) incorporation of maize straw at a medium rate of 9000 kg ha-1 (M); (iv) incorporation of maize straw at a high rate of 13 500 kg ha-1 (H). The results in the final year of treatments (2010) showed that the mean soil organic carbon storage of the 0-60 cm soil layers were significantly (P<0.05) increased with H, M, and L, by 21.40%, 20.38% and 8.21% compared with CK, respectively. Straw incorporation increased >0.25 mm water-stable macroaggregates level, geometric mean diameter, mean weight diameter and the aggregate stability, which were ranked in order of increasing straw incorporation rates: H/M > L > CK. Straw incorporation significantly (P<0.05) reduced the fractal dimension in the 0-40 cm soil layers compared with CK. Our results suggest that straw incorporation is an effective practice for improving the soil aggregate structure and stability. PMID:24663096

Zhang, Peng; Wei, Ting; Jia, Zhikuan; Han, Qingfang; Ren, Xiaolong; Li, Yongping

2014-01-01

390

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

391

Incorporation of Mean Stress Effects Into the Micromechanical Analysis of the High Strain Rate Response of Polymer Matrix Composites  

NASA Technical Reports Server (NTRS)

The results presented here are part of an ongoing research program, to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. A micromechanics approach is employed in this work, in which state variable constitutive equations originally developed for metals have been modified to model the deformation of the polymer matrix, and a strength of materials based micromechanics method is used to predict the effective response of the composite. In the analysis of the inelastic deformation of the polymer matrix, the definitions of the effective stress and effective inelastic strain have been modified in order to account for the effect of hydrostatic stresses, which are significant in polymers. Two representative polymers, a toughened epoxy and a brittle epoxy, are characterized through the use of data from tensile and shear tests across a variety of strain rates. Results computed by using the developed constitutive equations correlate well with data generated via experiments. The procedure used to incorporate the constitutive equations within a micromechanics method is presented, and sample calculations of the deformation response of a composite for various fiber orientations and strain rates are discussed.

Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

2002-01-01

392

Surface Charge Development on Transition Metal Sulfides: An Electrokinetic Study  

Microsoft Academic Search

The isoelectric points, pHi.e.p., of ZnS, PbS, CuFeS2, FeS, FeS2, NiS2, CoS2, and MnS2 in NaCl supported electrolyte solutions are estimated to be between pH 3.3 and 0.6, with most of the isoelectric points below pH 2. The first electrokinetic measurements on NiS2, CoS2, and MnS2 are reported here. Below pHi.e.p. the metal-sulfide surfaces are positively charged, above pHi.e.p. the

Joakim Bebie; Martin A. A. Schoonen; Mark Fuhrmann; Daniel R. Strongin

1998-01-01

393

High ionic strength electrokinetics of melamine-formaldehyde latex.  

PubMed

The electrokinetic potential of melamine-formaldehyde latex at high ionic strengths was measured by means of two different instruments. The present study confirms that the zeta potentials in 1 M 1-1 electrolyte solutions can be as high as +/-20 mV. The IEP of latex at low ionic strengths was at pH 11. The increase in the electrolyte concentration induced a shift in the IEP to low pH for all studied salts, and this indicates specific adsorption of the anions. The magnitude of the shift depends chiefly on the nature of the anion and increases in the series Cl < NO(3) = Br < I, and the nature of the cation (Li, Na, K, Cs) plays a rather insignificant role. PMID:16797575

Kosmulski, Marek; Dahlsten, Per; Próchniak, Piotr; Rosenholm, Jarl B

2006-09-15

394

Monolayers of cationic polyelectrolytes on mica--electrokinetic studies.  

PubMed

Physicochemical properties of cationic polyelectrolytes: poly(allylamine hydrochloride) (PAH), poly(ethylene imine) (PEI), and poly(dimethyldiallylammonium chloride) (PDDA), having molar mass of 70,000, 75,000, and 120,000, respectively, were examined and compared. The bulk characteristics comprised the diffusion coefficient and electrophoretic mobility determined as a function of pH (3.5-9) and ionic strengths (10(-4) M to 0.15 M NaCl). These measurements allowed one to determine theamount of electrokinetic charge of the polyelectrolyte molecules and their isoelectric points. On the other hand, formation of polyelectrolyte monolayers on mica and their properties were investigated using the in situ streaming potential method. Additionally, using this method, the stability of monolayers, evaluated via desorption kinetic measurements, was determined. The investigations showed that PAH molecules form the most stable monolayers, which can be used as supporting layers for particle deposition and multilayer formation. PMID:23849822

Morga, Maria; Adamczyk, Zbigniew

2013-10-01

395

Polymeric reagents for derivatizations in micellar electrokinetic chromatography.  

PubMed

A polymer immobilized o-nitrobenzophenone reagent was prepared for analysis of amine drugs in micellar electrokinetic chromatography (MEKC). A model compound, propylamine, was used to characterize the reagent's performance in MEKC. Derivatizations were performed on the CE instrument with reagent in the sample vial. The yielded derivative was directly sampled from the reaction mixture, and directly injected onto the MEKC system. The derivatization reagent was also applied to the derivatization of n-alkyl amine mixtures and amino acids. The method was validated for adamantanamine in urine and in plasma by single-blind spike analysis. Precisions and accuracies for all samples were less than 6.0% for urine samples and 10% for plasma samples. The procedure was a direct injection technique requiring minimal sample preparation for the analysis of drugs in biofluids. PMID:7841764

Szulc, M; Krull, I S

1994-01-01

396

Electrokinetic treatment of firing ranges containing tungsten-contaminated soils.  

PubMed

Tungsten-based alloys and composites are being used and new formulations are being considered for use in the manufacturing of different types of ammunition. The use of tungsten heavy alloys (WHA) in new munitions systems and tungsten composites in small caliber ammunition could potentially release substantial amounts of this element into the environment. Although tungsten is widely used in industrial and military applications, tungsten's potential environmental and health impacts have not been thoroughly addressed. This necessitates the research and development of remedial technologies to contain and/or remove tungsten from soils that may serve as a source for water contamination. The current work investigates the feasibility of using electrokinetics for the remediation of tungsten-contaminated soils in the presence of other heavy metals of concern such as Cu and Pb with aim to removing W from the soil while stabilizing in situ, Pb and Cu. PMID:17686582

Braida, Washington; Christodoulatos, Christos; Ogundipe, Adebayo; Dermatas, Dimitris; O'Connor, Gregory

2007-11-19

397

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

2013-07-01

398

Effect of Broccoli (Brassica oleracea) Tissue, Incorporated at Different Depths in a Soil Column, on Meloidogyne incognita  

PubMed Central

Brassicas have been used frequently for biofumigation, a pest-management strategy based on the release of biocidal volatiles during decomposition of soil-incorporated tissue. However, the role of such volatiles in control of plant-parasitic nematodes is unclear. The goal of this study was to determine the direct localized and indirect volatile effects of amending soil with broccoli tissue on root-knot nematode populations. Meloidogyne incognita-infested soil in 50-cm-long tubes was amended with broccoli tissue, which was mixed throughout the tube or concentrated in a 10-cm layer. After three weeks at 28°C, M. incognita populations in the amended tubes were 57 to 80% smaller than in non-amended tubes. Mixing broccoli throughout the tubes reduced M. incognita more than concentrating broccoli in a 10-cm layer. Amending a 10-cm layer reduced M. incognita in the non-amended layers of those tubes by 31 to 71%, probably due to a nematicidal effect of released volatiles. However, the localized direct effect was much stronger than the indirect effect of volatiles. The strong direct effect may have resulted from the release of non-volatile nematicidal compounds. Therefore, when using biofumigation with broccoli to control M. incognita, the tissue should be thoroughly and evenly mixed through the soil layer(s) where the target nematodes occur. Effects on saprophytic nematodes were the reverse. Amended soil layers had much greater numbers of saprophytic nematodes than non-amended layers, and there was no indirect effect of amendments on saprophytic nematodes in adjacent non-amended layers.

Roubtsova, Tatiana; Lopez-Perez, Jose-Antonio; Edwards, Scott; Ploeg, Antoon

2007-01-01

399

Effects of elemental composition on the incorporation of dietary nitrogen and carbon isotopic signatures in an omnivorous songbird  

SciTech Connect

Pearson, S.F., D.J. Levey, C.H. Greenberg, and C.M. del Rio. 2003. Effects of elemental composition on the incorporation of dietary nitrogen and carbon isotopic signatures in an omnivorous songbird. Oecologia. 135:516-523. The use of stable isotopes to infer diet requires quantifying the relationship between diet and tissues and, in particular, knowing of how quickly isotopes turnover in different tissues and how isotopic concentrations of different food components change (discriminate) when incorporated into consumer tissues. We used feeding trials with wild-caught yellow-rumped warblers (Dendroica coronata) to determine d15N and d13C turnover rates for blood, d15N and d13C diet-tissue discrimination factors, and diet-tissue relationships for blood and feathers. After 3 weeks on a common diet, 36 warblers were assigned to one of four diets differing in the relative proportion of fruit and insects. Plasma half-life estimates ranged from 0.4 to 0.7 days for d13C and from 0.5 to 1.7 days for d15N. Half-life did not differ among diets. Whole blood half-life for d13C ranged from 3.9 to 6.1 days. Yellow-rumped warbler tissues were enriched relative to diet by 1.7.3.6% for nitrogen isotopes and by 1.2 to 4.3% for carbon isotopes, depending on tissue and diet. Consistent with previous studies, feathers were the most enriched and whole blood and plasma were the least enriched or, in the case of carbon, slightly depleted relative to diet. In general, tissues were more enriched relative to diet for birds with high percentages of insects. For all tissues, carbon and nitrogen isotope discrimination factors increased with carbon and nitrogen concentrations of diets. The isotopic signature of plasma increased linearly with the sum of the isotopic signature of the diet and the discrimination factor. Because the isotopic signature of tissues depends on both elemental concentration and isotopic signature of the diet, attempts to reconstruct diet from stable isotope signatures require mixing models that incorporate elemental concentration.

Pearson, Scott, F.; Levey, Douglas, J.; Greenberg, Catheryn, H.; Martinez del Rio, Carlos

2003-02-28

400

Anomalous skin effect in a Drude-type model incorporating the spatial dispersion for systems with conductivity of metal  

NASA Astrophysics Data System (ADS)

Simple semiclassical model of the Drude-model type has been complemented recently by incorporation of the dependence on spatial variables. The model is rather encouraging in interpretation of novel high frequency effects induced by the spatial dispersion in high-Tc and ordinary superconductors. Anomalous skin effect, which is characteristic manifestation of the spatial dispersion in the microwave response of cooled conductors, is explored as a trial problem to estimate the potentialities of the model. A complex value of the surface impedance Z˜ = R + iX with the phase of ?/3 and with the dependence of the module on the microwave frequency |Z˜| ~ ?2/3 characteristic for an extremely anomalous regime is interpreted for modelling media (one-dimensional conductivity). The model describes these main features and indicates the manifestation: (i) of the spatial-resonance type effect resulting in the ?/3 value of the phase and (ii) of the excitation of additional waves in metal, which explains the dependence |Z˜| ~ ?2/3.

Karuzskii, A. L.; Perestoronin, A. V.; Volchkov, N. A.; Zherikhina, L. N.; Chernyaev, A. P.

2012-12-01

401

Studies on the effect of pilocarpine incorporation into a submicron emulsion on the stability of the drug and the vehicle.  

PubMed

In order to obtain a novel ocular formulation with a potential for prolonging pilocarpine activity, the drug (2.0%) was incorporated into a submicron emulsion containing soya-bean oil and lecithin as emulgator. The effect of drug incorporation into the emulsion on its physical stability and on the other hand, the potential of the vehicle to reduce drug degradation at pH higher than 5.0 was studied. The pH was adjusted to 6.5 or 5.0 and the physicochemical stability of the formulations was observed. The mean diameter of oily particles in the resulting emulsions measured by a laser diffractometer was 0.6-0.7 micron and this was larger than in a drug-free emulsion where a 0.33 micron value was measured. The formulations were physically stable for 6 months at 4 degrees C, but progressing chemical degradation of pilocarpine was noted at pH 6.5. At that pH nearly 8% of pilocarpine was degraded to isopilocarpine and pilocarpic acid, both in the emulsion and in the solution. Thus, it may be concluded that pilocarpine in submicron emulsion is not protected against degradation. The presence of pilocarpine changes the physical stability of the vehicle since the formulation was easily destabilized during autoclaving or at room temperature. In the presence of higher concentration of lecithin (2.4%) or co-emulgators (poloxamer 2.0% or Tween 80 0.5%) the mean droplet size in the emulsions was the same as in a drug-free system. However the emulsions containing poloxamer were not stable during storage. Viscosity of pilocarpine emulsions can be increased by addition of methylcellulose or sodium carmellose (1.0%), but an intensive creaming occurs in these systems. Pilocarpine base is less suitable for emulsion preparation than hydrochloride salt, and emulsions prepared at pH 5.0 show the most satisfying stability. PMID:10382109

Zurowska-Pryczkowska, K; Sznitowska, M; Janicki, S

1999-05-01

402

Electrokinetically induced alterations in dynamic response of viscoelastic fluids in narrow confinements.  

PubMed

We investigate a dynamical interplay between interfacial electrokinetics and a combined dissipative and elastic behavior of flow through narrow confinements, in analogy with spatiotemporal hydrodynamics of porous media. In particular, we investigate the effects of streaming potential on the pertinent dynamic responses, by choosing a Maxwell fluid model for representing the consequent electro-hydrodynamic characteristics. We transform the pertinent governing equation to the frequency domain, so that a dynamic generalization of Darcy's law in the presence of streaming potential effects can be effectively realized. We show that the frequencies corresponding to local maxima in the dynamic permeability also correspond to local maxima in the induced streaming potential. We also bring out the effects of Stern layer conductivity on the dynamic permeability. Our analytical estimates do reveal that serious overestimations in the commonly portrayed notion of massive amplifications of dynamic permeability at resonating frequencies may be possible, if interactions between spontaneous electrochemical interfacial phenomena and pulsating pressure-gradient-driven viscoelastic transport are trivially ignored. PMID:23004858

Bandopadhyay, Aditya; Chakraborty, Suman

2012-05-01

403

Incorporation of advanced aerosol activation treatments into CESM/CAM5: model evaluation and impacts on aerosol indirect effects  

NASA Astrophysics Data System (ADS)

One of the greatest sources of uncertainty in the science of anthropogenic climate change is from aerosol-cloud interactions. The activation of aerosols into cloud droplets is a direct microphysical link between aerosols and clouds; parameterizations of this process realistically link aerosol with cloud condensation nuclei (CCN) and the resulting indirect effects. Small differences between parameterizations can have a large impact on the spatiotemporal distributions of activated aerosols and the resulting cloud properties. In this work, we incorporate a series of aerosol activation schemes into the Community Atmosphere Model version 5.1.1 within the Community Earth System Model version 1.0.5 (CESM/CAM5), which include factors such as insoluble aerosol adsorption, giant cloud condensation nuclei (CCN) activation kinetics, and entrainment to understand their individual impacts on global scale cloud droplet number concentrations (CDNCs). Compared to the existing simple activation scheme in CESM/CAM5, this series of schemes predict CDNCs that are typically in better agreement with satellite-derived and observed values. The largest changes in predicted CDNCs occur over desert and oceanic regions, owing to the enhanced activation of dust from insoluble aerosol adsorption and reductions in cloud supersaturation from the intense absorption of water vapor in regions of strong giant CCN emissions (e.g., sea-salt). Comparison of CESM/CAM5 against satellite-derived cloud optical thickness and liquid water path shows that the updated activation schemes improve the low biases in their predictions. Globally, the incorporation of all updated schemes leads to an average increase in column CDNCs of 155%, an increase in shortwave cloud forcing of 13%, and a decrease in surface shortwave radiation of 4%. In terms of meteorological impacts, these updated aerosol activation schemes result in a slight decrease in near-surface temperature of 0.9 °C and precipitation of 0.04 mm day-1, respectively. With the improvement of model-predicted CDNCs and better agreement with most satellite-derived cloud properties, the inclusion of these aerosol activation processes should result in better predictions of the aerosol indirect effects.

Gantt, B.; He, J.; Zhang, X.; Zhang, Y.; Nenes, A.

2013-12-01

404

Hydrodynamics and electrokinetics of spherical liposomes with coatings of terminally anchored poly(ethylene glycol): Numerically exact electrokinetics with self-consistent mean-field polymer  

Microsoft Academic Search

A detailed theoretical model is presented to interpret electrokinetic experiments performed on colloids with uncharged polymer layers. The methodology removes many of the degrees of freedom that otherwise have to be accounted for by adopting multiple empirical fitting parameters. Furthermore, the level of detail provides a firm basis for future studies examining liposome surface chemistry and charge, surface-charge mobility, and

Reghan J. Hill

2004-01-01

405

Effect of incorporation of nanoscale bioactive glass and hydroxyapatite in PCL/chitosan nanofibers for bone and periodontal tissue engineering.  

PubMed

A biomimetic scaffold which can very closely mimic the extracellular matrix of the bone was fabricated by incorporating nano-bioceramic particles such as nano bioglass (nBG) and nano hydroxyapatite (nHAp) within electrospun nanofibrous scaffold. A comparative study between nHAp incorporated poly(caprolactone) (PCL)-chitosan (CS) and nBG incorporated PCL-CS nanofibrous scaffolds was carried out and their feasibility in tissue engineering was investigated. All the samples were optimized to obtain fibers of similar diameter from 100-200 nm for the ease of comparison between the samples. Protein adsorption studies showed that PCL-CS incorporated with 3 wt% nHAp and 3 wt% nBG adsorbed more proteins on their surface than other samples. Cell attachment and proliferation studies using human periodontal ligament fibroblast cells (hPLFs) and osteoblast like cells (MG-63 cell lines) showed that nBG incorporated samples are slightly superior to nHAp incorporated counterparts. Cell viability test using alamar blue assay and live/dead staining confirms that the scaffolds are cytocompatible. ALP activity confirmed the osteoblastic behavior of hPDLFs. Also the presence of nHAp and nBG enhanced the ALP activity of hPDLF on the PCH3 and PCB3 scaffolds. These studies indicate that nBG incorporated electrospun scaffolds are comparatively better candidates for orthopedic and periodontal tissue engineering applications. PMID:23620999

Shalumon, K T; Sowmya, S; Sathish, D; Chennazhi, K P; Nair, Shantikumar V; Jayakumar, R

2013-03-01

406

Incorporating social network effects into cost-effectiveness analysis: a methodological contribution with application to obesity prevention  

PubMed Central

Objectives To develop a methodology for integrating social networks into traditional cost-effectiveness analysis (CEA) studies. This will facilitate the economic evaluation of treatment policies in settings where health outcomes are subject to social influence. Design This is a simulation study based on a Markov model. The lifetime health histories of a cohort are simulated, and health outcomes compared, under alternative treatment policies. Transition probabilities depend on the health of others with whom there are shared social ties. Setting The methodology developed is shown to be applicable in any healthcare setting where social ties affect health outcomes. The example of obesity prevention is used for illustration under the assumption that weight changes are subject to social influence. Main outcome measures Incremental cost-effectiveness ratio (ICER). Results When social influence increases, treatment policies become more cost effective (have lower ICERs). The policy of only treating individuals who span multiple networks can be more cost effective than the policy of treating everyone. This occurs when the network is more fragmented. Conclusions (1) When network effects are accounted for, they result in very different values of incremental cost-effectiveness ratios (ICERs). (2) Treatment policies can be devised to take network structure into account. The integration makes it feasible to conduct a cost-benefit evaluation of such policies.

Konchak, Chad; Prasad, Kislaya

2012-01-01

407

Effects of Na incorporated at different periods of deposition on Cu(In,Ga)Se2 films.  

PubMed

Sodium was incorporated into Cu(In,Ga)Se(2) (CIGS) thin films by evaporating NaF before the second and third stages and after the third stage of CIGS deposition. The Na-doping dosage was precisely controlled by a light-controlling method based on reflected light signals. X-ray diffraction and scanning electron microscopy results reveal that CIGS crystalline growth and microstructure can be strongly influenced by periods of Na incorporation, which leads to different device performance characteristics. Based on the analysis of results, incorporating Na before the second stage of the standard three-stage process is suggested. PMID:20517377

Tan, Xiao Hui; Ye, Sheng Lin; Fan, Bin; Tang, Ken; Liu, Xu

2010-06-01

408

Effect of incorporation of Brassica napus L. residues in soils on mycorrhizal fungus colonisation of roots and phosphorus uptake by maize ( Zea mays L.)  

Microsoft Academic Search

Plants in the Brassicaceae family are known to contain thioglucoside compounds that produce isothiocyanates when tissues are disrupted. These chemicals have a negative effect on soil-borne fungal pathogens, and possibly on vesicular–arbuscular mycorrhizal (AM) fungi. We investigated the effect of incorporation of Brassica napus L. residues in a soil on mycorrhizal colonisation of roots, P uptake and growth of following

Sylvain Pellerin; Alain Mollier; Christian Morel; Christian Plenchette

2007-01-01

409

The effect of ethanol and/or acetaldehyde on the incorporation of U/sup 14/C-glucose into human umbilical artery lipids  

SciTech Connect

The effect of ethanol, acetaldehyde and a combination of ethanol and acetaldehyde added in vitro was determined on their abilities to alter conversion of glucose to lipid. When human umbilical arteries were perfused with acetaldehyde at a 0.5% concentration, a significant reduction (p less than 0.05) of /sup 14/C incorporation into lipid was observed. This reduction was found to be the result of depressed incorporation of glucose into phospholipid (PL) and triacylglycerides (TG). Acetaldehyde at a concentration of 0.25% appeared to depress incorporation; however, this was not significant. Acetaldehyde plus ethanol at final equal concentrations of 0.25%, 0.5% and 1.0% had no effect on incorporation of U/sup 14/ C-glucose into lipid. Ethanol at concentrations of 0.5%, 0.25% and 0.125% had no effect on the incorporation of U/sup 14/ C-glucose into lipid. The study suggests that acetaldehyde can depress the conversion of glucose into umbilical artery lipids. However, acetaldehyde in the presence of equal concentrations of ethanol does not exhibit this ability to depress conversion of glucose to lipids suggesting some cellular counter effect of these two agents.

Dupont, J.; Nelson, A.W.; Clow, D.J.

1982-01-01

410

Effects of germanium incorporation on optical performances of silicon germanium passive devices for group-IV photonic integrated circuits  

NASA Astrophysics Data System (ADS)

Optical interconnect in integrated optoelectronic circuits is one of the promising next-generation technologies for replacing metalized interconnect. Efforts have been made to use silicon (Si)-compatible materials such as germanium (Ge) and Ge-buffered III-V compound semiconductors, along with Si, as optical sources for Si and group-IV integrated optoelectronic systems. This opens the possibility that higher fraction of Ge with its high refractive index (n) can be incorporated in Si waveguide for optical interconnect and the graftability between Si and group-IV or III-V materials would be improved in silicon photonics. In this work, advantageous features of nano-structured silicon germanium (Si1-xGex) optical waveguide with different Ge fraction (x) were evaluated by both optical simulations and theoretical calculations, which are mainly found in the enhanced optical confinement and better interfacing capability. Along with the SiGe waveguide, performance of Si1-xGex microring resonator under material loss in the effect of extinction coefficient (k) has been investigated to suggest the necessity of optimizing the Ge content in Si1-xGex passive devices. While carrying out the establish design criteria, n and k have been modelled in closed-form functions of Ge fraction at 1550 nm. Furthermore, by examining high-resolution transmission electron microscopy (HR-TEM) images, process compatibility of Ge with either group-IV alloys or III-V compound semiconductors is confirmed for the monolithically integrated photonic circuits.

Cho, Seongjae; Park, Joonsuk; Kim, Hyungjin; Sinclair, Robert; Park, Byung-Gook; Harris, James S.

2014-02-01

411

Can neutral analytes be concentrated by transient isotachophoresis in micellar electrokinetic chromatography and how much?  

PubMed

Transient isotachophoresis (tITP) is a versatile sample preconcentration technique that uses ITP to focus electrically charged analytes at the initial stage of CE analysis. However, according to the ruling principle of tITP, uncharged analytes are beyond its capacity while being separated and detected by micellar electrokinetic chromatography (MEKC). On the other hand, when these are charged micelles that undergo the tITP focusing, one can anticipate the concentration effect, resulting from the formation of transient micellar stack at moving sample/background electrolyte (BGE) boundary, which increasingly accumulates the analytes. This work expands the enrichment potential of tITP for MEKC by demonstrating the quantitative analysis of uncharged metal-based drugs from highly saline samples and introducing to the BGE solution anionic surfactants and buffer (terminating) co-ions of different mobility and concentration to optimize performance. Metallodrugs of assorted lipophilicity were chosen so as to explore whether their varying affinity toward micelles plays the role. In addition to altering the sample and BGE composition, optimization of the detection capability was achieved due to fine-tuning operational variables such as sample volume, separation voltage and pressure, etc. The results of optimization trials shed light on the mechanism of micellar tITP and render effective determination of selected drugs in human urine, with practical limits of detection using conventional UV detector. PMID:24797392

Matczuk, Magdalena; Foteeva, Lidia S; Jarosz, Maciej; Galanski, Markus; Keppler, Bernhard K; Hirokawa, Takeshi; Timerbaev, Andrei R

2014-06-01

412

Effects of calcium ion incorporation on bone healing of Ti6Al4V alloy implants in rabbit tibiae.  

PubMed

The biocompatibility of calcium ion (Ca)-incorporated Ti6Al4V alloy implants, produced by hydrothermal treatment using a Ca-containing solution, was investigated. The surface characteristics were evaluated by scanning electron microscopy, thin-film X-ray diffractometry, Auger electron spectroscopy, and stylus profilometry. The viability of MC3T3-E1 cells on Ca-incorporated machined Ti6Al4V surfaces with different oxide thicknesses was compared with that on untreated machined Ti6Al4V surfaces with MTT assay. The osteoconductivity of the Ca-incorporated Ti6Al4V implants was evaluated by removal torque testing and histomorphometric analysis after 6 weeks of implantation in rabbit tibiae. Our results show that hydrothermal treatment with a Ca-containing solution produced a crystalline CaTiO(3) layer on Ti6Al4V surfaces, and calcium ions were gradually incorporated throughout the oxide layer. After immersion in Hank's balanced salt solution, a considerable apatite deposition was observed on all surfaces of the Ca-incorporated samples. Significant increases in cell viability (p<0.001), removal torque forces, and bone-to-implant contact values (p<0.05) were observed for Ca-incorporate