Science.gov

Sample records for incorporating electrokinetic effects

  1. Electrokinetic effects near a membrane

    NASA Astrophysics Data System (ADS)

    Lacoste, David

    2009-03-01

    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.

  2. Study of electrokinetic effects to quantify groundwater flow

    SciTech Connect

    Brown, S.R.; Haupt, R.W.

    1997-04-01

    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.

  3. Electrokinetic effects on detection time of nanowire biosensor

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    SciTech Connect

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

    2000-03-15

    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%.

  5. Electrokinetic remediation of concrete: effect of chelating agents.

    PubMed

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

    2008-05-01

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

  6. Electrokinetics of suspended charged particles taking into account the excluded volume effect.

    PubMed

    Aranda-Rascón, M J; Grosse, C; López-García, J J; Horno, J

    2009-07-15

    In two recent works [López-García et al., J. Colloid Interface Sci. 316 (2007) 196; López-García et al., J. Colloid Interface Sci. 323 (2008) 146] we presented a simple modification of the standard electrokinetic model that takes into account the finite size of ions in the electrolyte solution. In the first we presented numerical results for the equilibrium properties while, in the second, we calculated the effect of the excluded ion volume on the electrophoretic mobility. In the present work we first extend our previous results incorporating a distance of closest approach of the ions to the particle surface. We then calculate the conductivity increment and present a detailed interpretation of the mobility and conductivity increment results, based on the analysis of the equilibrium and field-induced ion concentrations and of the convective fluid flow in the neighborhood of the particle surface. We show that the inclusion of the ion size effect generally improves the predictions of the standard electrokinetic model: both the electrophoretic mobility and the conductivity increment increase. We also show that, largely due to the above-noted extension of considering a minimum approach distance between the ions and the particle surface, the excluded volume effect is not negligible even for weakly charged particles. PMID:19427641

  7. Sub-Grid Modeling of Electrokinetic Effects in Micro Flows

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    2005-01-01

    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.

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

    PubMed Central

    Haber, N

    1982-01-01

    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 PMID:6952183

  9. Electrokinetics of charged spherical colloidal particles taking into account the effect of ion size constraints.

    PubMed

    López-García, J J; Aranda-Rascón, M J; Grosse, C; Horno, J

    2011-04-01

    The electrokinetic properties of suspended spherical particles are examined using a modified standard electrokinetic model, which takes into account the finite ion size and considers that the minimum approach distance of ions to the particle surface need not be equal to their effective radius in the bulk solution. We calculate the conductivity increment and the electrophoretic mobility and present a detailed interpretation of the obtained results, based on the analysis of the equilibrium and field-induced ion concentrations, as well as the convective fluid flow in the neighborhood of the particle surface. We show that when charge reversal takes place, the sign of the concentration polarization remains unchanged while the sign of the electrophoretic mobility only changes under favorable circumstances. PMID:21281935

  10. Effects of surface roughness and electrokinetic heterogeneity on electroosmotic flow in microchannel

    NASA Astrophysics Data System (ADS)

    Masilamani, Kannan; Ganguly, Suvankar; Feichtinger, Christian; Bartuschat, Dominik; Rüde, Ulrich

    2015-06-01

    In this paper, a hybrid lattice-Boltzmann and finite-difference (LB-FD) model is applied to simulate the effects of three-dimensional surface roughness and electrokinetic heterogeneity on electroosmotic flow (EOF) in a microchannel. The lattice-Boltzmann (LB) method has been employed to obtain the flow field and a finite-difference (FD) method is used to solve the Poisson-Boltzmann (PB) equation for the electrostatic potential distribution. Numerical simulation of flow through a square cross-section microchannel with designed roughness is conducted and the results are critically analysed. The effects of surface heterogeneity on the electroosmotic transport are investigated for different roughness height, width, roughness interval spacing, and roughness surface potential. Numerical simulations reveal that the presence of surface roughness changes the nature of electroosmotic transport through the microchannel. It is found that the electroosmotic velocity decreases with the increase in roughness height and the velocity profile becomes asymmetric. For the same height of the roughness elements, the EOF velocity rises with the increase in roughness width. For the heterogeneously charged rough channel, the velocity profile shows a distinct deviation from the conventional plug-like flow pattern. The simulation results also indicate locally induced flow vortices which can be utilized to enhance the flow and mixing within the microchannel. The present study has important implications towards electrokinetic flow control in the microchannel, and can provide an efficient way to design a microfluidic system of practical interest.

  11. Ion size effects on the electrokinetics of salt-free concentrated suspensions in ac fields

    E-print Network

    Rafael Roa; Félix Carrique; Emilio Ruiz-Reina

    2012-08-01

    We analyze the influence of finite ion size effects in the response of a salt-free concentrated suspension of spherical particles to an oscillating electric field. Salt-free suspensions are just composed of charged colloidal particles and the added counterions released by the particles to the solution, that counterbalance their surface charge. In the frequency domain, we study the dynamic electrophoretic mobility of the particles and the dielectric response of the suspension. We find that the Maxwell-Wagner-O'Konski process associated with the counterions condensation layer, is enhanced for moderate to high particle charges, yielding an increment of the mobility for such frequencies. We also find that the increment of the mobility grows with ion size and particle charge. All these facts show the importance of including ion size effects in any extension attempting to improve standard electrokinetic models.

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

    SciTech Connect

    Krause, T.R.; Tarman, B.

    1993-10-01

    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 of electrically induced changes in the chemical environment of the system. Numerous factors, such as temperature, may affect each of these phenomena and, consequently, the overall process efficiency. We have begun an investigation of thermal effects in the extraction of potassium dichromate from kaolinite soils under conditions of constant saturation and dewatering. Preliminary results suggest that increasing the soil temperature from 21 to 55{degrees}C may decrease the processing time under saturated conditions. However, increasing the soil temperature under dewatering, conditions causes soil cracking, which reduces the overall process efficiency.

  13. Lattice Boltzmann simulations of electrokinetic coupling : effects of rugosity and local conductivity

    NASA Astrophysics Data System (ADS)

    Fiorentino, Eve-Agnès; Toussaint, Renaud; Jouniaux, Laurence

    2015-04-01

    Streaming-potentials are produced by electrokinetic effects in relation to fluid flow, and are used for geophysical prospecting. The electrokinetic coupling is induced by the coupling between the fluid flow and the electrical flow, which results from the presence of an electrical double layer at the rock/pore water interface. When fluid flows through a porous medium, it gives rise to an electric streaming current, counterbalanced by a conduction current, leading to a resulting measurable electrical voltage. Streaming current generation is well understood in water-saturated porous media, but the streaming potential coefficient at very-low and very-high salinities can show a non-linear behaviour. The aim of this study is to model the streaming potential coefficient using Lattice Boltzmann simulations and to quantify the effect of parameters such as fluid conductivity and rugosity. The lattice Boltzmann method is computational fluid dynamics technique that allows to solve advection and diffusion phenomena. We implement a coupled lattice Boltzmann algorithm that solves both the flow in a rock channel and the electrical diffusion to calculate the streaming potential coefficient (ratio between the created potential difference and the applied pressure gradient) in various situations. In this study, we aim at quantifying the change that is brought by taking into account the dependence of the local fluid conductivity on the local concentration. We also observe the influence of a rough surface on the behaviour of this coefficient with the fluid salinity. We try to generate non-linearities regarding the theoretical prediction of the streaming potential coefficient with a view to explaining existing experimental measurements.

  14. Effects of system variables on surfactant enhanced electrokinetic removal of polycyclic aromatic hydrocarbons from clayey soils.

    PubMed

    Saichek, R E; Reddy, K R

    2003-04-01

    Numerous polycyclic aromatic hydrocarbon (PAH)-contaminated sites threaten public health and the environment because PAHs are commonly toxins, mutagens, and/or carcinogens. PAHs are hydrophobic and resistant to degradation; therefore, conventional remediation methods are often costly or inefficient, especially when the PAHs are present in low permeability clayey soils. Electrokinetically enhanced in-situ oil flushing is an innovative technology that has the potential to greatly increase soil-solution-contaminant interaction and remedial efficiency, even under low permeability soil conditions. Although this technique is promising, many system variables may affect remedial efficiency, such as the surfactant concentration, pH control and voltage gradient. The objective of this investigation was to evaluate the effects of these system variables. Bench-scale electrokinetic experiments were conducted using various operating conditions, which included deionized water or a 3% or a 5% surfactant concentration flushing solution. Additional tests were also conducted using the 5% surfactant concentration along with a higher pH solution or a larger voltage gradient. The experiments employing the surfactant flushing solution had a lower electroosmotic flow but exhibited greater contaminant desorption, solubilization and migration. The benefits of using a higher pH solution or a larger voltage gradient were difficult to discern because changing these process variables did not significantly improve remedial efficiency. Overall, the results indicated that the surfactant flushing solution was advantageous for treating the soil near the anode region, but contaminant migration was limited by changes in the soil and/or solution chemistry that occurred with time and/or distance from the anode. PMID:12755451

  15. Electrokinetic pump

    DOEpatents

    Patel, Kamlesh D. (Dublin, CA)

    2007-11-20

    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.

  16. Electrokinetic Power Generation from Liquid Water Microjets

    SciTech Connect

    Duffin, Andrew M.; Saykally, Richard J.

    2008-02-15

    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%.

  17. Secondary flow effect on electrokinetic transport in curved channels and microfluidic mixing

    NASA Astrophysics Data System (ADS)

    Chun, Myung-Suk; Lim, Jin-Myeong

    2010-11-01

    This presentation reports the numerical framework and important new results regarding the velocity pattern, vorticity, and mixing property, with variations of channel geometry and heterogeneity of surface properties. Extending our previous studies, secondary Dean flow in curved rectangular microchannels is examined by applying the finite volume/SIMPLE algorithm for the pressure-driven electrokinetic transport coupled with the Poisson-Boltzmann/Navier-Stokes/Nernst-Planck equations. Hydrophilic glass and hydrophobic polymers with fluid slip are combined to create different channel configurations with ranging complementary aspect ratios. Simulation results show that, contrary to the case of narrow-bore channels, the streamwise axial velocity tends to shift toward the inner wall caused by a stronger effect of the spanwise pressure gradient. We observe the presence of pairs of counter-rotating vortices perpendicular to the flow direction and evaluate the circulation magnitude. The increasing rate of inner shift with increasing curvature ratio is more significant in the shallow channel, and the patterns of axial velocity and vorticity alter by the heterogeneity effect of surfaces occupying a large area. In addition, the inertial force should be considered for precise control of the micro- or nanoflows.

  18. Novel Electrokinetic Microfluidic Detector for Evaluating Effectiveness of Microalgae Disinfection in Ship Ballast Water.

    PubMed

    Maw, Myint Myint; Wang, Junsheng; Li, Fabo; Jiang, Jinhu; Song, Younan; Pan, Xinxiang

    2015-01-01

    Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a novel, simple and fast platform of methodology in evaluating the efficiency and the best parameters for ballast water treatment systems, particularly in chemical disinfection. In this study, a microfluidic chip with six sample wells and a waste well was designed, where sample transportation was controlled by electrokinetic flow. The performance of this microfluidic platform was evaluated by detecting the disinfection of Dunaliella salina (D. salina) algae in ballast water treated by sodium hypochlorite (NaClO) solution. Light-induced chlorophyll fluorescence (LICF) intensity was used to determine the viability of microalgae cells in the system, which can be operated automatically with the dimension of the detector as small as 50 mm × 24 mm × 5 mm. The 40 µL volume of sample solution was used for each treatment condition test and the validity of detection can be accomplished within about five min. The results show that the viability of microalgae cells under different treatment conditions can be determined accurately and further optimal treatment conditions including concentrations of NaClO and treatment time can also be obtained. These results can provide accurate evaluation and optimal parameters for ballast water treatment methods. PMID:26516836

  19. Depth-resolved detection of electrokinetic effects in cartilage using differential phase sensitive optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Youn, Jong-In; Akkin, Taner; Wong, Brian J. F.; Peavy, George M.; Milner, Thomas E.

    2003-06-01

    Osteoarthritis is a heterogeneous disease characterized by progressive loss of cartilage. The earliest biochemical features, which precede gross pathological changes, include non-uniform loss of proteoglycans associated with increase of water content in tissue and finally, fibrillation of the tissue's collagen network. Loss of proteoglycans decreases the ability of cartilage to withstand compressive loading and makes the tissue softer and more susceptible to wear and fibrilation. If the early loss of proteoglycans is detectable by a non-invasive optical technique, progression of the disease may be arrested using, for example, pharmacologic or surgical intervention. When an electric field is applied to cartilage by an electrical stimulator, the current-generated stress gradients are produced and stress deformation occurs. Since differential phase optical coherence tomography is very sensitive to subsurface stress deformation, we propose to stimulate cartilage electrically and detect stress gradients before gross signs of cartilage degeneration appear. Detection of depth-resolved electromechanical stress gradients in cartilage using differential phase optical coherence tomography may be useful to monitor non-invasively cartilage degeneration. Since the streaming potential and other electrokinetic effects in cartilage are directly proportional to proteoglycan density, application of an electric field in cartilage combined with depth-resolved phase sensitive optical measurements may provide a sensitive indicator of cartilage viability on the molecular-level.

  20. Novel Electrokinetic Microfluidic Detector for Evaluating Effectiveness of Microalgae Disinfection in Ship Ballast Water

    PubMed Central

    Maw, Myint Myint; Wang, Junsheng; Li, Fabo; Jiang, Jinhu; Song, Younan; Pan, Xinxiang

    2015-01-01

    Ship ballast water treatment methods face many technical challenges. The effectiveness of every treatment method usually is evaluated by using large scale equipment and a large volume of samples, which involves time-consuming, laborious, and complex operations. This paper reports the development of a novel, simple and fast platform of methodology in evaluating the efficiency and the best parameters for ballast water treatment systems, particularly in chemical disinfection. In this study, a microfluidic chip with six sample wells and a waste well was designed, where sample transportation was controlled by electrokinetic flow. The performance of this microfluidic platform was evaluated by detecting the disinfection of Dunaliella salina (D. salina) algae in ballast water treated by sodium hypochlorite (NaClO) solution. Light-induced chlorophyll fluorescence (LICF) intensity was used to determine the viability of microalgae cells in the system, which can be operated automatically with the dimension of the detector as small as 50 mm × 24 mm × 5 mm. The 40 µL volume of sample solution was used for each treatment condition test and the validity of detection can be accomplished within about five min. The results show that the viability of microalgae cells under different treatment conditions can be determined accurately and further optimal treatment conditions including concentrations of NaClO and treatment time can also be obtained. These results can provide accurate evaluation and optimal parameters for ballast water treatment methods. PMID:26516836

  1. Electrokinetics of non-Newtonian fluids: a review.

    PubMed

    Zhao, Cunlu; Yang, Chun

    2013-12-01

    This work presents a comprehensive review of electrokinetics pertaining to non-Newtonian fluids. The topic covers a broad range of non-Newtonian effects in electrokinetics, including electroosmosis of non-Newtonian fluids, electrophoresis of particles in non-Newtonian fluids, streaming potential effect of non-Newtonian fluids and other related non-Newtonian effects in electrokinetics. Generally, the coupling between non-Newtonian hydrodynamics and electrostatics not only complicates the electrokinetics but also causes the fluid/particle velocity to be nonlinearly dependent on the strength of external electric field and/or the zeta potential. Shear-thinning nature of liquids tends to enhance electrokinetic phenomena, while shear-thickening nature of liquids leads to the reduction of electrokinetic effects. In addition, directions for the future studies are suggested and several theoretical issues in non-Newtonian electrokinetics are highlighted. PMID:24148843

  2. ac electrokinetic micropumps: The effect of geometrical confinement, Faradaic current injection, and nonlinear surface capacitance

    E-print Network

    electric fields to induce electrokinetic pumping. However, classical dc electro- osmosis requires. ac electro-osmosis has recently been observed to induce fluid motion over pairs of microelectrodes 2 that for maximal pumping in the "forward" direction 11 and Ramos and co-workers observed reversal of the pumping

  3. Nanopore density effect of polyacrylamide gel plug on electrokinetic ion enrichment in a micro-nanofluidic chip

    NASA Astrophysics Data System (ADS)

    Wang, Jun-yao; Xu, Zheng; Li, Yong-kui; Liu, Chong; Liu, Jun-shan; Chen, Li; Du, Li-qun; Wang, Li-ding

    2013-07-01

    In this paper, the nanopore density effect on ion enrichment is quantitatively described with the ratio between electrophoresis flux and electroosmotic flow flux based on the Poisson-Nernst-Planck equations. A polyacrylamide gel plug is integrated into a microchannel to form a micro-nanofluidic chip. With the chip, electrokinetic ion enrichment is relatively stable and enrichment ratio of fluorescein isothiocyanate can increase to 600-fold within 120 s at the electric voltage of 300 V. Both theoretical research and experiments show that enrichment ratio can be improved through increasing nanopore density. The result will be beneficial to the design of micro-nanofluidic chips.

  4. Electrokinetic delivery of persulfate to remediate PCBs polluted soils: Effect of different activation methods.

    PubMed

    Fan, Guangping; Cang, Long; Gomes, Helena I; Zhou, Dongmei

    2016-02-01

    Persulfate-based in-situ chemical oxidation (ISCO) for the remediation of organic polluted soils has gained much interest in last decade. However, the transportation of persulfate in low-permeability soil is very low, which limits its efficiency in degrading soil pollutants. Additionally, the oxidation-reduction process of persulfate with organic contaminants takes place slowly, while, the reaction will be greatly accelerated by the production of more powerful radicals once it is activated. Electrokinetic remediation (EK) is a good way for transporting persulfate in low-permeability soil. In this study, different activation methods, using zero-valent iron, citric acid chelated Fe(2+), iron electrode, alkaline pH and peroxide, were evaluated to enhance the activity of persulfate delivered by EK. All the activators and the persulfate were added in the anolyte. The results indicated that zero-valent iron, alkaline, and peroxide enhanced the transportation of persulfate at the first stage of EK test, and the longest delivery distance reached sections S4 or S5 (near the cathode) on the 6th day. The addition of activators accelerated decomposition of persulfate, which resulted in the decreasing soil pH. The mass of persulfate delivered into the soil declined with the continuous decomposition of persulfate by activation. The removal efficiency of PCBs in soil followed the order of alkaline activation > peroxide activation > citric acid chelated Fe(2+) activation > zero-valent iron activation > without activation > iron electrode activation, and the values were 40.5%, 35.6%, 34.1%, 32.4%, 30.8% and 30.5%, respectively. The activation effect was highly dependent on the ratio of activator and persulfate. PMID:26347936

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

    PubMed

    El-Gholabzouri; Cabrerizo; Hidalgo-Álvarez

    1999-06-15

    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

  6. Electrokinetic pumps and actuators

    SciTech Connect

    Phillip M. Paul

    2000-03-01

    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.

  7. Electrokinetic improvement of offshore foundations

    NASA Astrophysics Data System (ADS)

    Micic, Silvana

    Offshore and near-shore structures for energy exploration and production, harbour work and other facilities are often situated on very soft marine clay deposits that have shear strengths of a few kilopascals. The design of foundations embedded in these soft deposits often poses a challenge for geotechnical engineers, i.e., to satisfy the bearing capacity requirement, while at the same time minimizing the embedment depth and dimensions of the foundation due to cost considerations. The present study investigates the possibility of using electrokinetics to strengthen the soil adjacent to skirted foundations embedded in soft marine deposits and, thus, to improve the load carrying capacity of the foundations. The innovative feature of this approach as compared to soil improvement methods commonly adopted in practice is that the focus of strengthening is on the interface between the soil and embedded foundation, in terms of enhancement of adhesion and cementation. The thesis presents a summary of the method and results of a series of electrokinetic tests conducted on natural and simulated marine clays in small-scale and large-scale laboratory testing facilities. Steel plates and steel cylinders are used to simulate skirted foundations. A low dc voltage is applied via steel electrodes installed around the foundation models. The effects of electrokinetics are evaluated through changes in the geotechnical properties of the soil and load carrying capacities of the foundation model after treatment. The results demonstrate that the load carrying capacity of the skirted foundation model and the undrained shear strength of the adjacent soil increase by a factor of three after electrokinetic treatment. The clay adheres strongly to the inside and outside walls of the foundation model, indicating bonding occurs between the soil and steel after treatment. The treatment increases the soil undrained modulus and also induces a preconsolidation pressure of the remoulded clay, thereby reducing potential settlement of the foundation. The new technology described in this thesis has potential application in offshore engineering for increasing the load carrying capacity of skirted foundations installed in soft clayey sediments, as well as for rehabilitation of existing offshore structures.

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

    SciTech Connect

    Vijh, A.K.

    1997-05-01

    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.

  9. Mass transport in a porous microchannel for non-Newtonian fluid with electrokinetic effects.

    PubMed

    Mondal, Sourav; De, Sirshendu

    2013-03-01

    Quantification of mass transfer in porous microchannel is of paramount importance in several applications. Transport of neutral solute in presence of convective-diffusive EOF having non-Newtonian rheology, in a porous microchannel was presented in this article. The governing mass transfer equation coupled with velocity field was solved along with associated boundary conditions using a similarity solution method. An analytical solution of mass transfer coefficient and hence, Sherwood number were derived from first principles. The corresponding effects of assisting and opposing pressure-driven flow and EOF were also analyzed. The influence of wall permeation, double-layer thickness, rheology, etc. on the mass transfer was also investigated. Permeation at the wall enhanced the mass transfer coefficient more than five times compared to impervious conduit in case of pressure-driven flow assisting the EOF at higher values of ?h. Shear thinning fluid exhibited more enhancement of Sherwood number in presence of permeation compared to shear thickening one. The phenomenon of stagnation was observed at a particular ?h (?2.5) in case of EOF opposing the pressure-driven flow. This study provided a direct quantification of transport of a neutral solute in case of transdermal drug delivery, transport of drugs from blood to target region, etc. PMID:23192435

  10. Long-time self-diffusion of charged colloidal particles: Electrokinetic and hydrodynamic interaction effects

    NASA Astrophysics Data System (ADS)

    McPhie, Mathieu G.; Nägele, Gerhard

    2007-07-01

    The authors analyze the long-time self-diffusion of charge-stabilized colloidal macroions in nondilute suspensions using a mode-coupling scheme developed for multicomponent suspensions of interacting Brownian spheres. In this scheme, all ionic species, including counterions and electrolyte ions, are treated on an equal footing as charged hard spheres undergoing overdamped Brownian motion. Hydrodynamic interactions between all ions are accounted for on the far-field level. We show that the influence on the colloidal long-time self-diffusion coefficient arising from the relaxation of the microionic atmosphere surrounding the colloids, the so-called electrolyte friction effect, is usually insignificant in comparison with the friction contributions arising from direct and hydrodynamic interactions between the colloidal particles. This finding is true even for small colloid concentrations unless the mobility difference between colloidal particles and microions is not large. Furthermore, we observe an interesting nonmonotonic density dependence of the colloidal long-time self-diffusion coefficient in suspensions with low amount of added salt. We show that this unusual density dependence is due to colloid-colloid hydrodynamic interactions.

  11. Dual opposite injection electrokinetic chromatography: nonionic microemulsion pseudostationary phase and novel approach to electrokinetic sampling bias.

    PubMed

    Zhou, Marilyn X; Foley, Joe P

    2004-02-01

    Dual opposite injection capillary electrophoresis (DOI-CE) is a family of CE techniques in which the sample is introduced into both ends of the capillary. For the analysis of compounds with widely varying pKa values using a voltage-driven separation scheme, DOI-CE is superior to conventional CE with sample introduction at only one end of the capillary due to DOI-CE's broader elution window. To enhance the DOI-CE separation, a running buffer with a microemulsion system was developed. Since DOI-CE works best under conditions of low electroosmotic flow (EOF), the suppression of EOF via the addition of a multiply charged cation (e.g., Zn2+) to the buffer was investigated, and was found to suppress the EOF effectively at moderate concentrations (2.5-10 mM). Three different dual opposite injection modes were studied: simultaneous electrokinetic injection, sequential electrokinetic injection, and sequential hydrodynamic injection. The injection bias in the first two electrokinetic injection modes was compared with the sequential hydrodynamic injection. Corrections in the bias of the electrokinetic injections were discussed, and an improved approach was suggested. Finally, the effect of the relative concentration of the multiply charged cation in the sample plug and running buffer on the peak shape of co-electroosmotic and counter-electroosmotic ions was examined, and found to be much more influential on the latter. PMID:14981693

  12. 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

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

    2010-01-01

    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

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

    PubMed

    Saichek, Richard E; Reddy, Krishna R

    2003-04-01

    Polycyclic aromatic hydrocarbon (PAH)-contaminated soils exist at numerous sites, and these sites may threaten public health and the environment because many PAH compounds are toxic, mutagenic, and/or carcinogenic. PAHs are also hydrophobic and persistent, so conventional remediation methods are often costly or inefficient, especially when the contaminants are present in low permeability and/or organic soils. An innovative technique, electrokinetically enhanced in situ flushing, has the potential to increase soil-solution-contaminant interaction and PAH removal efficiency for low permeability soils; however, the electrolysis reaction at the anode may adversely affect the remediation of low acid buffering capacity soils, such as kaolin. Therefore, the objective of this study was to improve the remediation of low acid buffering soils by controlling the pH at the anode to counteract the electrolysis reaction. Six bench-scale electrokinetic experiments were conducted, where each test employed one of three different flushing solutions, deionized water, a surfactant, or a cosolvent. For each of these solutions, tests were performed with and without a 0.01 M NaOH solution at the anode to control the pH. The test using deionized water with pH control generated a higher electroosmotic flow than the equivalent test performed without pH control, but the electroosmotic flow difference between the surfactant and cosolvent tests with and without pH control was minor compared to that observed with the deionized water tests. Controlling the pH was beneficial for increasing contaminant solubilization and migration from the soil region adjacent to the anode, but the high contaminant concentrations that resulted in the middle or cathode soil regions indicates that subsequent changes in the soil and/or solution chemistry caused contaminant deposition and low overall contaminant removal efficiency. PMID:12604079

  14. Competition between Dukhin's and Rubinstein's electrokinetic modes

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  15. Induced-charge electrokinetic phenomena

    E-print Network

    Bazant, Martin Z.

    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. ...

  16. Electrokinetic transport in microchannels with random roughness

    SciTech Connect

    Wang, Moran; Kang, Qinjun

    2008-01-01

    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.

  17. Electrokinetic remediation prefield test methods

    NASA Technical Reports Server (NTRS)

    Hodko, Dalibor (Inventor)

    2000-01-01

    Methods for determining the parameters critical in designing an electrokinetic soil remediation process including electrode well spacing, operating current/voltage, electroosmotic flow rate, electrode well wall design, and amount of buffering or neutralizing solution needed in the electrode wells at operating conditions are disclosed These methods are preferably performed prior to initiating a full scale electrokinetic remediation process in order to obtain efficient remediation of the contaminants.

  18. EMERGING TECHNOLOGY BULLETIN: ELECTROKINETIC SOIL PROCESSING

    EPA Science Inventory

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

  19. ELECTROKINETIC REMEDIATION: BASICS AND TECHNOLOGY STATUS

    EPA Science Inventory

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

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

    PubMed

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

    2013-08-01

    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

  1. Estimation of electrokinetic and hydrodynamic global properties of relevant amyloid-beta peptides through the modeling of their effective electrophoretic mobilities and analysis of their propensities to aggregation.

    PubMed

    Deiber, Julio A; Piaggio, Maria V; Peirotti, Marta B

    2014-09-01

    Neuronal activity loss may be due to toxicity caused by amyloid-beta peptides forming soluble oligomers. Here amyloid-beta peptides (1-42, 1-40, 1-39, 1-38, and 1-37) are characterized through the modeling of their experimental effective electrophoretic mobilities determined by a capillary zone electrophoresis method as reported in the literature. The resulting electrokinetic and hydrodynamic global properties are used to evaluate amyloid-beta peptide propensities to aggregation through pair particles interaction potentials and Brownian aggregation kinetic theories. Two background electrolytes are considered at 25°C, one for pH 9 and ionic strength I = 40 mM (aggregation is inhibited through NH4OH) the other for pH 10 and I = 100 mM (without NH4OH). Physical explanations of peptide oligomerization mechanisms are provided. The effect of hydration, electrostatic, and dispersion forces in the amyloidogenic process of amyloid-beta peptides (1-40 and 1-42) are quantitatively presented. The interplay among effective charge number, hydration, and conformation of chains is described. It is shown that amyloid-beta peptides (1-40 and 1-42) at pH 10, I = 100 mM and 25°C, may form soluble oligomers, mainly of order 2 and 4, after an incubation of 48 h, which at higher times evolve and end up in complex structures (protofibrils and fibrils) found in plaques associated with Alzheimer's disease. PMID:24975363

  2. Electrokinetics over liquid/liquid interfaces

    NASA Astrophysics Data System (ADS)

    Squires, Todd M.

    2011-11-01

    Since liquid-liquid interfaces flow in response to an applied stress, one might expect electrokinetic flows at liquid-liquid interfaces to be significantly higher than over liquid-solid interfaces. The earliest predictions for the electrophoretic mobility of charged mercury drops - distinct approaches by Frumkin and Levich (1946), and Booth (1951) - differed by O (a /?D) , where a is the radius of the drop and ?D is the Debye screening length. Seeking to reconcile this rather striking discrepancy, Levine (1973) showed double-layer polarization to be the key ingredient. Without a physical mechanism by which electrokinetic effects are enhanced, however, it is difficult to know how general the enhancement is - whether it holds only for liquid metal surfaces, or more generally, for all liquid/liquid surfaces. By considering a series of systems in which a planar metal strip is coated with either a liquid metal or liquid dielectric, we show that the central physical mechanism behind the enhancement predicted by Frumkin and Levich (1946) is the presence of an unmatched electrical stress upon the electrolyte-liquid interface, which establishes a Marangoni stress on the droplet surface and drives it into motion. The source of the unbalanced electrokinetic stress on a liquid metal surface is clear - metals represent equipotential surfaces, so no field exists to drive an equal and opposite force on the surface charge. This might suggest that liquid metals represent a unique system, since dielectric liquids can support finite electric fields, which might be expected to exert an electrical stress on the surface charge that balances the electric stress. We demonstrate, however, that electrical and osmotic stresses on relaxed double-layers internal to dielectric liquids precisely cancel, so that internal electrokinetic stresses generally vanish in closed, ideally polarizable liquids. The enhancement for liquid mercury drops can thus be expected quite generally over clean, ideally polarizable liquid drops. More broadly, the ability to reliably engineer liquid interfaces in microfluidic systems, then, may provide a path to significantly enhanced electrokinetic flows. Research done in collaboration with A. J. Pascall.

  3. Laboratory Experiment on Electrokinetic Remediation of Soil

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  4. Near-anode focusing phenomenon caused by the coupling effect of early precipitation and backward electromigration in electrokinetic remediation of MSWI fly ashes.

    PubMed

    Li, Dongwei; Huang, Tao; Liu, Kexiang

    2016-01-01

    As electrokinetic remediation (EKR) is used to remediate contaminated soil, the focusing phenomenon is always the inevitable problems needing to be solved during the process. In this paper, EKR was chosen to extract the heavy metals in the municipal solid waste incineration fly ashes (FAs). The focusing phenomenon of FA in the sample region of the rectangular electrolyser was comprehensively studied. The formation of the focusing band was monitored and the redistribution of concentration for Zn, Pb, Cu, and Cd were displayed. The major and minor phases of FA particles have greatly changed before and after the experiment. A variety of carbonate hydroxides and phosphate were found at the end of the test. There are two focusing bands at S2 and S5, separately for all the four elements and the focusing bands in the S2 zone forming at the early stage existed nearly throughout the entire process. The pH gradient between S1 and S2 was detected at the onset of the experiment, and until the 12 day, the gradient barrier was obviously dropped down. The coupling effect of precipitation hindering and backward electromigration of anions is considered as the dominant force for the formation of the focusing band, which is different from the pure ion-induced potential gradient well trapping effect near the anode. The FA matrix enhancing and nitric acid enhancing can alleviate the focusing phenomenon and increase the concentration ratios to some extent. PMID:26119872

  5. Effective Incorporation of Double Look-Ahead Procedures

    E-print Network

    Kuzmanov, Georgi

    Effective Incorporation of Double Look-Ahead Procedures Marijn Heule and Hans van Maaren Department of Technology marijn@heule.nl, h.vanmaaren@tudelft.nl Abstract. We introduce an adaptive algorithm to control

  6. Electrokinetic high pressure hydraulic system

    DOEpatents

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

    2000-01-01

    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.

  7. Electrokinetic techniques applied to electrochemical DNA biosensors.

    PubMed

    Mir, Mònica; Martínez-Rodríguez, Sergio; Castillo-Fernández, Oscar; Homs-Corbera, Antoni; Samitier, Josep

    2011-04-01

    Electrokinetic techniques are contact-free methods currently used in many applications, where precise handling of biological entities, such as cells, bacteria or nucleic acids, is needed. These techniques are based on the effect of electric fields on molecules suspended in a fluid, and the corresponding induced motion, which can be tuned according to some known physical laws and observed behaviours. Increasing interest on the application of such strategies in order to improve the detection of DNA strands has appeared during the recent decades. Classical electrode-based DNA electrochemical biosensors with combined electrokinetic techniques present the advantage of being able to improve the working electrode's bioactive part during their fabrication and also the hybridization yield during the sensor detection phase. This can be achieved by selectively manipulating, driving and directing the molecules towards the electrodes increasing the speed and yield of the floating DNA strands attached to them. On the other hand, this technique can be also used in order to make biosensors reusable, or reconfigurable, by simply inverting its working principle and pulling DNA strands away from the electrodes. Finally, the combination of these techniques with nanostructures, such as nanopores or nanochannels, has recently boosted the appearance of new types of electrochemical sensors that exploit the time-varying position of DNA strands in order to continuously scan these molecules and to detect their properties. This review gives an insight into the main forces involved in DNA electrokinetics and discusses the state of the art and uses of these techniques in recent years. PMID:21425177

  8. Electrokinetically pumped high pressure sprays

    SciTech Connect

    Schoeniger, Joseph S.; Paul, Phillip H.; Schoeniger, Luke

    2005-11-01

    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.

  9. Electrokinetically pumped high pressure sprays

    SciTech Connect

    Schoeniger, Joseph S.; Paul, Phillip H.; Schoeniger, Luke

    2002-01-01

    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.

  10. Electrokinetic confinement of axonal growth for dynamically configurable neural networks

    PubMed Central

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

    2013-01-01

    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. PMID:23314575

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

    SciTech Connect

    Wittle, J.K.; Pamukcu, S.

    1993-04-01

    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.

  12. Electrokinetic high pressure hydraulic system

    DOEpatents

    Paul, Phillip H.; Rakestraw, David J.; Arnold, Don W.; Hencken, Kenneth R.; Schoeniger, Joseph S.; Neyer, David W.

    2003-06-03

    An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based system. 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.

  13. Electrokinetic high pressure hydraulic system

    DOEpatents

    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

    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.

  14. 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)

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

    2013-12-01

    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.

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

    SciTech Connect

    1998-12-31

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

  16. REMOVAL OF RADIONUCLIDES BY ELECTROKINETIC SOIL PROCESSING

    EPA Science Inventory

    Electrokinetics promises to be an innovative treatment process for in-situ treatment of soils and groundwater contaminated with heavy metals and radionuclides. Electrokinetics refers to the movement of ionic liquids and charged particles relative to one another under the action ...

  17. Electrokinetic remediation of fluorine-contaminated soil and its impact on soil fertility.

    PubMed

    Zhou, Ming; Wang, Hui; Zhu, Shufa; Liu, Yana; Xu, Jingming

    2015-11-01

    Compared to soil pollution by heavy metals and organic pollutants, soil pollution by fluorides is usually ignored in China. Actually, fluorine-contaminated soil has an unfavorable influence on human, animals, plants, and surrounding environment. This study reports on electrokinetic remediation of fluorine-contaminated soil and the effects of this remediation technology on soil fertility. Experimental results showed that electrokinetic remediation using NaOH as the anolyte was a considerable choice to eliminate fluorine in contaminated soils. Under the experimental conditions, the removal efficiency of fluorine by the electrokinetic remediation method was 70.35 %. However, the electrokinetic remediation had a significant impact on the distribution and concentrations of soil native compounds. After the electrokinetic experiment, in the treated soil, the average value of available nitrogen was raised from 69.53 to 74.23 mg/kg, the average value of available phosphorus and potassium were reduced from 20.05 to 10.39 mg/kg and from 61.31 to 51.58 mg/kg, respectively. Meanwhile, the contents of soil available nitrogen and phosphorus in the anode regions were higher than those in the cathode regions, but the distribution of soil available potassium was just the opposite. In soil organic matter, there was no significant change. These experiment results suggested that some steps should be taken to offset the impacts, after electrokinetic treatment. PMID:26109225

  18. Effects of flyash incorporation in cement and concrete

    SciTech Connect

    Diamond, S.

    1981-01-01

    This symposium dealt with the properties of flyash; flyash reactions with cements and cement components including reaction kinetics and microstructure formation; the effects of flyash incorporation on the properties and performance of concretes (e.g., curing time, water requirements, temperature effects, strength properties, shrinkage, air entrainment, and wear resistance); global aspects, standardization, and practical experience in the utilization of flyash in concretes; and properties of other mineral wastes related to flyash. Separate abstracts were prepared for most of the 33 papers presented. 279 references. (CKK)

  19. The optimisation of electrokinetic remediation for heavy metals and radioactivity contamination on Holyrood-Lunas soil (acrisol species) in Sri Gading Industrial Area, Batu Pahat, Johor, Malaysia.

    PubMed

    Mohamed Johar, S; Embong, Z

    2015-11-01

    The optimisation of electrokinetic remediation of an alluvial soil, locally named as Holyrood-Lunas from Sri Gading Industrial Area, Batu Pahat, Johor, Malaysia, had been conducted in this research. This particular soil was chosen due to its relatively high level of background radiation in a range between 139.2 and 539.4 nGy h(-1). As the background radiation is correlated to the amount of parent nuclides, (238)U and (232)Th, hence, a remediation technique, such as electrokinetic, is very useful in reducing these particular concentrations of heavy metal and radionuclides in soils. Several series of electrokinetics experiments were performed in laboratory scale in order to study the influence of certain electrokinetic parameters in soil. The concentration before (pre-electrokinetic) and after the experiment (post-electrokinetic) was determined via X-ray fluorescence (XRF) analysis technique. The best electrokinetic parameter that contributed to the highest achievable concentration removal of heavy metals and radionuclides on each experimental series was incorporated into a final electrokinetic experiment. Here, High Pure Germanium (HPGe) was used for radioactivity elemental analysis. The XRF results suggested that the most optimised electrokinetic parameters for Cr, Ni, Zn, As, Pb, Th and U were 3.0 h, 90 volts, 22.0 cm, plate-shaped electrode by 8 × 8 cm and in 1-D configuration order whereas the selected optimised electrokinetic parameters gave very low reduction of (238)U and (232)Th at 0.23 ± 2.64 and 2.74 ± 23.78 ppm, respectively. PMID:25920778

  20. Dielectrophoretic concentration of particles under electrokinetic flow

    DOEpatents

    Miles, Robin R.; Bettencourt, Kerry A.; Fuller, Christopher K.

    2004-09-07

    The use of dielectrophoresis to collect particles under the conditions of electrokinetically-driven flow. Dielectrophortic concentration of particles under electrokinetic flow is accomplished by interdigitated electrodes patterned on an inner surface of a microfluid channel, a DC voltage is applied across the ends to the channel, and an AC voltage is applied across the electrodes, and particles swept down the channel electrokinetically are trapped within the field established by the electrodes. The particles can be released when the voltage to the electrodes is released.

  1. Effect of thin oxide layers incorporated in spin valve structures

    NASA Astrophysics Data System (ADS)

    Gillies, M. F.; Kuiper, A. E. T.; Leibbrandt, G. W. R.

    2001-06-01

    The enhancement of the magnetoresistance effect, induced by incorporating nano-oxide layers (NOLs) in a bottom-type spin valve, was studied for various preparation conditions. The effect of a NOL in the Co90Fe10 pinned layer was found to depend critically on the oxygen pressure applied to form the thin oxide film. Pressures over 10-3 Torr O2 yield oxides thicker than about 0.7 nm, which apparently deteriorate the biasing field which exists over the oxide. The magnetoresistance values can further be raised by forming a specular reflecting oxide on top of the sense layer. Promising results were obtained with an Al2O3 capping layer formed in a solid-state oxidation reaction that occurs spontaneously when a thin Al layer is deposited on the oxidized surface of the Co90Fe10 sense layer.

  2. Electrokinetic instability of isotachophoresis shocks

    NASA Astrophysics Data System (ADS)

    Garcia, Giancarlo; Santiago, Juan; Mani, Ali

    2013-11-01

    Isotachophoresis (ITP) is an electrokinetic focusing technique used in a variety of life science and analytical chemistry applications. In ITP, an electrokinetic shock wave forms at the interface between leading and trailing electrolytes with relatively high and low conductivities. The ITP interface is self-sharpening, as restoring electromigration fluxes counteract molecular diffusion. However, the large electric field gradient at the shock interface also gives rise to free charge and strong electrostatic body forces. At large applied currents, electrostatic forces cause recirculating flows which destabilize the ITP interface. We performed stability analysis and direct simulation of ITP shocks through numerical solutions to the coupled Nernst-Planck and Navier-Stokes equations using a quasi-electroneutral approximation. In both experiments and numerical simulations, we observe two modes of instability: 1) a distorted ITP interface which is steady in time, and 2) an oscillating perturbation which persists. In addition, at the highest simulated electric fields, we observe transition towards more chaotic oscillatory modes. We use our stability analysis and numerical simulations to characterize instability of ITP shocks using two dimensionless parameters.

  3. Electrokinetics of scalable, electric-field-assisted fabrication of vertically aligned carbon-nanotube/polymer composites

    NASA Astrophysics Data System (ADS)

    Castellano, Richard J.; Akin, Cevat; Giraldo, Gabriel; Kim, Sangil; Fornasiero, Francesco; Shan, Jerry W.

    2015-06-01

    Composite thin films incorporating vertically aligned carbon nanotubes (VACNTs) offer promise for a variety of applications where the vertical alignment of the CNTs is critical to meet performance requirements, e.g., highly permeable membranes, thermal interfaces, dry adhesives, and films with anisotropic electrical conductivity. However, current VACNT fabrication techniques are complex and difficult to scale up. Here, we describe a solution-based, electric-field-assisted approach as a cost-effective and scalable method to produce large-area VACNT composites. Multiwall-carbon nanotubes are dispersed in a polymeric matrix, aligned with an alternating-current (AC) electric field, and electrophoretically concentrated to one side of the thin film with a direct-current (DC) component to the electric field. This approach enables the fabrication of highly concentrated, individually aligned nanotube composites from suspensions of very dilute ( ? = 4 × 10 - 4 ) volume fraction. We experimentally investigate the basic electrokinetics of nanotube alignment under AC electric fields, and show that simple models can adequately predict the rate and degree of nanotube alignment using classical expressions for the induced dipole moment, hydrodynamic drag, and the effects of Brownian motion. The composite AC + DC field also introduces complex fluid motion associated with AC electro-osmosis and the electrochemistry of the fluid/electrode interface. We experimentally probe the electric-field parameters behind these electrokinetic phenomena, and demonstrate, with suitable choices of processing parameters, the ability to scalably produce large-area composites containing VACNTs at number densities up to 1010 nanotubes/cm2. This VACNT number density exceeds that of previous electric-field-fabricated composites by an order of magnitude, and the surface-area coverage of the 40 nm VACNTs is comparable to that of chemical-vapor-deposition-grown arrays of smaller-diameter nanotubes.

  4. 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...

  5. Electrokinetic properties of polymer colloids

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

  6. Induced-charge Electrokinetic Phenomena

    E-print Network

    Bazant, M Z; Bazant, Martin Z.; Squires, Todd M.

    2003-01-01

    Motivated by the recent discovery of AC electro-osmosis near micro-electrodes, we predict a broad class of nonlinear electrokinetic phenomena involving induced interfacial charge. By considering various polarizable objects (metals or dielectrics) in DC and AC applied fields, we develop a simple physical picture of `induced-charge electro-osmosis' (ICEO), the fluid slip at a surface due to an electric field acting on the diffuse charge it induces. We also discuss `induced-charge electrophoresis' (ICEP), the analogous motion of a freely-suspended polarizable particle. Both differ significantly from their classical linear counterparts. We present a mathematical theory of ICEO flows in the weakly nonlinear limit of thin double layers. As an example, we calculate the time-dependent ICEO slip around a metallic sphere with a thin dielectric coating in a suddenly-applied DC field. We briefly discuss possible applications of ICEO to microfluidics and of ICEP to colloidal manipulation.

  7. Electrokinetic Concentration of DNA Polymers in Nanofluidic Channels

    E-print Network

    Dekker, Cees

    Electrokinetic Concentration of DNA Polymers in Nanofluidic Channels Derek Stein,, Zeno Deurvorst on this understanding by demonstrating how a nanofluidic device with integrated electrodes can preconcentrate DNA. KEYWORDS Nanofluidic, DNA, electrokinetic, concentration M iniature fluidic devices are having an important

  8. Effect of thin oxide layers incorporated in spin valve structures

    SciTech Connect

    Gillies, M. F.; Kuiper, A. E. T.; Leibbrandt, G. W. R.

    2001-06-01

    The enhancement of the magnetoresistance effect, induced by incorporating nano-oxide layers (NOLs) in a bottom-type spin valve, was studied for various preparation conditions. The effect of a NOL in the Co{sub 90}Fe{sub 10} pinned layer was found to depend critically on the oxygen pressure applied to form the thin oxide film. Pressures over 10{sup {minus}3}Torr O{sub 2} yield oxides thicker than about 0.7 nm, which apparently deteriorate the biasing field which exists over the oxide. The magnetoresistance values can further be raised by forming a specular reflecting oxide on top of the sense layer. Promising results were obtained with an Al{sub 2}O{sub 3} capping layer formed in a solid-state oxidation reaction that occurs spontaneously when a thin Al layer is deposited on the oxidized surface of the Co{sub 90}Fe{sub 10} sense layer. {copyright} 2001 American Institute of Physics.

  9. Adverse effects of incorporating ketoprofen into established rodent studies.

    PubMed

    Lamon, Tennille K; Browder, Elizabeth J; Sohrabji, Farida; Ihrig, Melanie

    2008-07-01

    The use of analgesics to prevent or treat postprocedural pain in rodents is increasingly encouraged by the laboratory animal community and federal funding agencies. However, the effects of analgesics on experimental outcomes are not well-documented. In this study, we incorporated ketoprofen into a well-established experimental protocol. Of the 44 Sprague-Dawley (SD) rats obtained from vendor A that were given either ketoprofen (10 mg/kg s.c.) or saline and underwent ovariectomy, 19 that received ketoprofen died or were euthanized due to clinical illness within 3 to 7 d after surgery. Necropsy revealed gastrointestinal ulceration consistent with toxicity from nonsteroidal antiinflammatory drug. In an attempt to identify factors responsible for this unanticipated outcome, SD rats from vendors A and B were subjected to the same protocol, but no clinical signs or pathologic lesions were observed in any of these rats, regardless of source. A third experiment with rats obtained from vendor A and housed in barriers 1 and 2 was done to clarify the conflicting results and to determine whether response to ketoprofen differed at the barrier level. Three of the 6 rats from barrier 2 that received ketoprofen in the third study had gastrointestinal lesions similar to those observed in the fi rst study, whereas none of the rats from barrier 1 had any lesions. These results suggest that the adverse effects seen after administration of ketoprofen were due to differences between barriers. PMID:18702447

  10. Adverse Effects of Incorporating Ketoprofen into Established Rodent Studies

    PubMed Central

    Lamon, Tennille K; Browder, Elizabeth J; Sohrabji, Farida; Ihrig, Melanie

    2008-01-01

    The use of analgesics to prevent or treat postprocedural pain in rodents is increasingly encouraged by the laboratory animal community and federal funding agencies. However, the effects of analgesics on experimental outcomes are not well-documented. In this study, we incorporated ketoprofen into a well-established experimental protocol. Of the 44 Sprague–Dawley (SD) rats obtained from vendor A that were given either ketoprofen (10 mg/kg SC) or saline and underwent ovariectomy, 19 that received ketoprofen died or were euthanized due to clinical illness within 3 to 7 d after surgery. Necropsy revealed gastrointestinal ulceration consistent with toxicity from nonsteroidal antiinflammatory drug. In an attempt to identify factors responsible for this unanticipated outcome, SD rats from vendors A and B were subjected to the same protocol, but no clinical signs or pathologic lesions were observed in any of these rats, regardless of source. A third experiment with rats obtained from vendor A and housed in barriers 1 and 2 was done to clarify the conflicting results and to determine whether response to ketoprofen differed at the barrier level. Three of the 6 rats from barrier 2 that received ketoprofen in the third study had gastrointestinal lesions similar to those observed in the first study, whereas none of the rats from barrier 1 had any lesions. These results suggest that the adverse effects seen after administration of ketoprofen were due to differences between barriers. PMID:18702447

  11. Analysis of electrokinetic transport of a spherical particle in a microchannel.

    PubMed

    Unni, Harikrishnan N; Keh, Huan J; Yang, Chun

    2007-02-01

    Electrokinetically driven microfluidic devices that are used for biological cell/particle manipulation (e.g., cell sorting, separation) involve electrokinetic transport of these particles in microchannels whose dimension is comparable with particles' size. This paper presents an analytical study on electrokinetic transport of a charged spherical particle in a charged parallel-plate microchannel. Under the thin electric double-layer assumption, solutions in closed-form solutions for the particle velocity and disturbed electrical and fluid velocity fields are obtained for plane-symmetric (along the channel centerline) and asymmetric (off the channel centerline) motions of a sphere in a parallel-plate microchannel. The effects of relative particle size and eccentricity (i.e., off the centerline distance) on a particle's translational and rotational velocities are analyzed. PMID:17304499

  12. Impact of electrokinetic remediation on microbial communities within PCP contaminated soil.

    PubMed

    Lear, G; Harbottle, M J; Sills, G; Knowles, C J; Semple, K T; Thompson, I P

    2007-03-01

    Electrokinetic techniques have been used to stimulate the removal of organic pollutants within soil, by directing contaminant migration to where remediation may be more easily achieved. The effect of this and other physical remediation techniques on the health of soil microbial communities has been poorly studied and indeed, largely ignored. This study reports the impact on soil microbial communities during the application of an electric field within ex situ laboratory soil microcosms contaminated with pentachlorophenol (PCP; 100mg kg(-1) oven dry soil). Electrokinetics reduced counts of culturable bacteria and fungi, soil microbial respiration and carbon substrate utilisation, especially close to the acidic anode where PCP accumulated (36d), perhaps exacerbated by the greater toxicity of PCP at lower soil pH. There is little doubt that a better awareness of the interactions between soil electrokinetic processes and microbial communities is key to improving the efficacy and sustainability of this remediation strategy. PMID:17045711

  13. Investigation of the surfactant type and concentration effect on the retention factors of glutathione and its analogues by micellar electrokinetic chromatography.

    PubMed

    Kazarjan, Jana; Mahlapuu, Riina; Hansen, Mats; Soomets, Ursel; Kaljurand, Mihkel; Vaher, Merike

    2015-10-01

    In the present study, a micellar electrokinetic chromatographic method was used to determine the retention factors of hydrophilic monomeric and homodimeric forms of glutathione analogues. Ionic-liquid-based surfactant, 1-tetradecyl-3-methylimidazolium chloride, as well as cetyltrimethylammonium bromide and phosphate buffer (pH 7.4) were employed in the experiments. Since the studied peptides possess a negative charge under physiological conditions, it is expected that the peptides interact with the oppositely charged 1-tetradecyl-3-methylimidazolium chloride and cetyltrimethylammonium bromide micelles via hydrophobically assisted electrostatic forces. The dependence of the retention factor on the micellar concentration of 1-tetradecyl-3-methylimidazolium chloride and cetyltrimethylammonium bromide is nonlinear and the obtained curves converge to a limiting value. The retention factor values of GSH analogues were in the range of 0.36-2.22 for glutathione analogues and -1.21 to 0.37 for glutathione when 1-tetradecyl-3-methylimidazolium chloride was used. When cetyltrimethylammonium bromide was employed, the retention factor values were in the range of 0.27-2.17 for glutathione analogues and -1.22 to 0.06 for glutathione. If sodium dodecyl sulfate was used, the retention factor values of glutathione analogues with carnosine moiety were in the range of -1.54 to 0.38. PMID:26200325

  14. Electrokinetic Remediation: I. Modeling of simple systems

    SciTech Connect

    Wilson, D.J.; Rodriguez-Maroto, J.M.; Gomez-Lahoz, C.

    1995-09-01

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

  15. Bound soda incorporation during hydrate precipitation -- Effects of caustic, temperature and organics

    SciTech Connect

    Armstrong, L.; Hunter, J.; McCormick, K.; Warren, H.

    1996-10-01

    Soda is incorporated into aluminum tri-hydroxide (hydrate) during the precipitation stage of the Bayer Process. A review of literature shows the predominant effect is alumina supersaturation. This research extends the literature by quantifying the secondary effects of temperature, caustic and organics on soda incorporation beyond the primary effect through alumina supersaturation. This work advances industry knowledge towards better control of soda incorporation in the refinery in the pursuit of higher and more consistent product quality for smelter grade alumina.

  16. Electrokinetic treatment of hazardous wastes in soil and groundwater

    SciTech Connect

    Loo, W.W.

    1995-09-01

    Electrokinetic (EK) treatment processes are recognized by the US department of Defense, US Department of Energy, and the US EPA as the most potentially cost effective treatment of hazardous wastes. Recently, EK has attracted the attention of Dupont, General Electric, and Monsanto for various aspects of hazardous waste treatment. Electrolysis and electro-osmosis are known electrokinetic processes. Electrolysis is one of the principal industrial process used in the production of aluminum, chlorine, metal plating, welding, corrosion protection, etc. Electro-osmosis is a very well established process used to dewater and stabilize the clayey foundations of buildings and structures. These processes are very effective in the treatment of hazardous metals and organic compounds in soil, sludge, and water. Electrolysis can be applied in both permeable and impermeable media. It can be used as a neutralization process for pH control. It can also be used for the isolation or capture of metallic ions, or positively charged ions, at and near the cathode electrode. and negatively charged ions at and near the anode electrode. Electrolyis will also oxidize petroleum hydrocarbons and benzene-based organic chemicals such as PCBs, pesticides, and PAHs. Electro-osmosis can be used in the treatment of hazardous chemicals in silty and clayey material. The electro-osmotic process causes and imbalance of charge bonds in clayey material that results in clay compaction and chemical desorption. The compaction and desorption processes will reduce the cleanup time and are particularly successful in the desorption of organic chemicals and metals from clayey materials. This accelerates and improves the performance of typically inefficient pump and treat projects. Electrokinetic processes can be applied both above ground (ex situ) or in the subsurface (in situ).

  17. Nonlinear electrokinetic flow about a polarized conducting drop

    NASA Astrophysics Data System (ADS)

    Schnitzer, Ory; Yariv, Ehud

    2013-04-01

    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.

  18. Transient behavior of heavy metals in soils during electrokinetic remediation.

    PubMed

    Al-Hamdan, Ashraf Z; Reddy, Krishna R

    2008-03-01

    This paper presents a systematic bench-scale laboratory study performed to assess the transient behavior of chromium, nickel, and cadmium in different soils during electrokinetic remediation. A series of laboratory electrokinetic experiments was conducted using two different clayey soils, kaolin and glacial till. For each type of soil, four electrokinetic experiments with 1, 2, 4, and 10 d of treatment time were performed. In all tests, the contaminants were Cr(VI), Ni(II), and Cd(II) combined in the soil. A geochemical assessment was performed using the geochemical model MINEQL(+) to determine the partitioning of the heavy metals in soils as precipitated, adsorbed, and aqueous forms. Results showed that in kaolin, the extent of Ni(II) and Cd(II) migration towards the cathode increased as the treatment time increased. Unlike kaolin, in glacial till treatment time had no effect on nickel and cadmium migration because of its high buffering capacity. In both kaolin and glacial till, the extent of Cr(VI) migration towards the anode increased as the treatment time increased. However, Cr(VI) migration was higher in glacial till as compared to kaolin because of the high pH conditions that existed in glacial till. In all tests, some Cr(VI) was reduced to Cr(III), and the Cr(VI) reduction rate to Cr(III) as well as the Cr(III) migration were significantly affected by the treatment time. Overall, this study showed that the electroosmotic flow as well as the direction and extent of contaminant migration and removal depend on the polarity of the contaminant, the type of soil, and the treatment duration. PMID:18155269

  19. Enhanced electrokinetic treatment of marine sediments contaminated by heavy metals and PAHs.

    PubMed

    Colacicco, Antonio; De Gioannis, Giorgia; Muntoni, Aldo; Pettinao, Emmanuela; Polettini, Alessandra; Pomi, Raffaella

    2010-09-01

    Dredged sediments contaminated by heavy metals and PAHs were subjected to both unenhanced and enhanced electrokinetic remediation under different operating conditions, obtained by varying the applied voltage and the type of conditioning agent used at the electrode compartments in individual experiments. While metals were not appreciably mobilized as a result of the unenhanced process, metal removal was found to be significantly improved when both the anodic and cathodic reservoirs were conditioned with the chelating agent EDTA, with removal yields ranging from 28% to 84% depending on the contaminant concerned. As for the effect on organic contaminants, under the conditions tested the electrokinetic treatment displayed a poor removal capacity towards PAHs, even when a surfactant (Tween 80) was used to promote contaminant mobilization, indicating the need for further investigation on this issue. Further research on organics removal from this type of materials through electrokinetic remediation is thus required. Furthermore, a number of technical and environmental issues will also require a careful evaluation with a view to full-scale implementation of electrokinetic sediment remediation. These include controlling side effects during the treatment (such as anodic precipitation, oxidation of the conditioning agent, and evolution of toxic gases), as well as evaluating the potential ecotoxicological effects of the chemical agents used. PMID:20691460

  20. Eur. Phys. J. E 28, 243264 (2009) DOI: 10.1140/epje/i2008-10433-1 Electrostatic and electrokinetic contributions to

    E-print Network

    Lacoste, David

    2009-01-01

    .39.Wj Ion exchange, dialysis, osmosis, electro- osmosis, membrane processes ­ 05.70.Np Interface in the fluctuation spectrum, which we relate to a nonlinear (E2 ) electrokinetic effect called induced-charge electro-osmosis

  1. Modeling the electrokinetic decontamination of concrete

    SciTech Connect

    Harris, M.T.; DePaoli, D.W.; Ally, M.R.

    1997-01-01

    The decontamination of concrete is a major concern in many Department of (DOE) facilities. Numerous techniques (abrasive methods, manual methods, ultrasonics, concrete surface layer removal, chemical extraction methods, etc.) have been used to remove radioactive contamination from the surface of concrete. Recently, processes that are based on electrokinetic phenomena have been developed to decontaminate concrete. Electrokinetic decontamination has been shown to remove from 70 to over 90% of the surface radioactivity. To evaluate and improve the electrokinetic processes, a model has been developed to simulate the transport of ionic radionuclei constituents through the pores of concrete and into the anolyte and catholyte. The model takes into account the adsorption and desorption kinetics of the radionuclei from the pore walls, and ion transport by electro-osmosis, electromigration, and diffusion. A numerical technique, orthogonal collocation, is used to simultaneously solve the governing convective diffusion equations for a porous concrete slab and the current density equation. This paper presents the theoretical framework of the model and the results from the computation of the dynamics of ion transport during electrokinetic treatment of concrete. The simulation results are in good agreement with experimental data.

  2. Opto-electrokinetic manipulation technique for highperformance

    SciTech Connect

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

    2012-01-01

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

  3. Nonlinear electrokinetic phenomena in microfluidic devices

    NASA Astrophysics Data System (ADS)

    Ben, Yuxing

    This thesis addresses nonlinear electrokinetic mechanisms for transporting fluid and particles in microfluidic devices for potential applications in biomedical chips, microelectronic cooling and micro-fuel cells. Nonlinear electrokinetics have many advantages, such as low voltage, low power, high velocity, and no significant gas formation in the electrolyte. However, they involve new and complex charging and flow mechanisms that are still not fully understood or explored. Linear electrokinetic fingering that occurs when a fluid with a lower electrolyte concentration advances into one with a higher concentration is first analyzed. Unlike earlier miscible fingering theories, the linear stability analysis is carried out in the self-similar coordinates of the diffusing front. This new spectral theory is developed for small-amplitude gravity and viscous miscible fingering phenomena in general and applied to electrokinetic miscible fingering specifically. Transient electrokinetic fingering is shown to be insignificant in sub-millimeter micro-devices. Nonlinear electroosmotic flow around an ion-exchange spherical granule is studied next. When an electric field is applied across a conducting and ion-selective porous granule in an electrolyte solution, a polarized surface layer with excess counter-ions is created. The flux-induced polarization produces a nonlinear slip velocity to produce micro-vortices around this sphere. This polarization layer is reduced by convection at high velocity. Two velocity scalings at low and high electric fields are derived and favorably compared with experimental results. A mixing device based on this mechanism is shown to produce mixing efficiency 10-100 times higher than molecular diffusion. Finally, AC nonlinear electrokinetic flow on planar electrodes is studied. Two double layer charging mechanisms are responsible for the flow---one due to capacitive charging of ions from the bulk electrolyte and one due to Faradaic reactions at the electrode that consume or produce ions in the double layer. Faradaic charging is analyzed for specific reactions. From the theory, particular electrokinetic flows above the electrodes are selected for micropumps and bioparticle trapping by specifying the electrode geometry and the applied voltage and frequency.

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

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

    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.

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

    E-print Network

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

    2008-10-27

    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 in [D. Lacoste, M. Cosentino Lagomarsino, and J. F. Joanny, Europhys. Lett., {\\bf 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; in contrast, we predict "reverse" ICEO flows around driven membranes, due to curvature-induced tangential fields within a non-equilibrium 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.

  6. Pore network model of electrokinetic transport through charged porous media.

    PubMed

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

    2014-04-01

    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

  7. AC Electrokinetics of Physiological Fluids for Biomedical Applications.

    PubMed

    Lu, Yi; Liu, Tingting; Lamanda, Ariana C; Sin, Mandy L Y; Gau, Vincent; Liao, Joseph C; Wong, Pak Kin

    2015-12-01

    Alternating current (AC) electrokinetics is a collection of processes for manipulating bulk fluid mass and embedded objects with AC electric fields. The ability of AC electrokinetics to implement the major microfluidic operations, such as pumping, mixing, concentration, and separation, makes it possible to develop integrated systems for clinical diagnostics in nontraditional health care settings. The high conductivity of physiological fluids presents new challenges and opportunities for AC electrokinetics-based diagnostic systems. In this review, AC electrokinetic phenomena in conductive physiological fluids are described followed by a review of the basic microfluidic operations and the recent biomedical applications of AC electrokinetics. The future prospects of AC electrokinetics for clinical diagnostics are presented. PMID:25487557

  8. Improving electrokinetic microdevice stability by controlling electrolysis bubbles.

    PubMed

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

    2014-07-01

    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

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Masi, Matteo; Pazzi, Veronica; Losito, Gabriella

    2013-04-01

    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.

  11. Comparing micellar electrokinetic chromatography and microemulsion electrokinetic chromatography for the analysis of preservatives in pharmaceutical and cosmetic products.

    PubMed

    Huang, Hsi-Ya; Lai, Yu-Cheng; Chiu, Chen-Wen; Yeh, Jui-Ming

    2003-04-18

    In this study, separation and determination of nine preservatives ranging from hydrophilic to hydrophobic properties, which are commonly used as additives in various pharmaceutical and cosmetic products, by micellar electrokinetic chromatograpy (MEKC) and microemulsion electrokinetic chromatography (MEEKC) were compared. The effect of temperature, buffer pH, and concentration of surfactant on separation were examined. In MEKC, the separation resolution of preservatives improved markedly by changing the sodium dodecyl sulfate concentration. Temperature and pH of running buffers were used mainly to shorten the magnitude of separation time. However, in order to detect all preservatives in a single run in a MEEKC system, a microemulsion of higher pH was needed. The separation resolution was improved dramatically by changing temperature, and a higher concentration of SDS was necessary for maintaining a stable microemulsion solution, therefore the separation of the nine preservatives in MEEKC took longer than in MEKC. An optimum MEKC method for separation of the nine preservatives was obtained within 9.0 min with a running buffer of pH 9.0 containing 20 mM SDS at 25 degrees C. A separation with baseline resolution was also obtained within 16 min using a microemulsion of pH 9.5 which composed of SDS, 1-butanol, and octane, and a shorter capillary column at 34 degrees C. Finally, the developed MEKC and MEEKC methods determined successfully preservatives in various cosmetic and pharmaceutical products. PMID:12735448

  12. Quartz channel fabrication for electrokinetically driven separations

    NASA Astrophysics Data System (ADS)

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

    1998-09-01

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

  13. Quartz Channel Fabrication for Electrokinetically Driven Separations

    SciTech Connect

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

    1998-12-01

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

  14. Immersed molecular electrokinetic finite element method

    NASA Astrophysics Data System (ADS)

    Kopacz, Adrian M.; Liu, Wing K.

    2013-07-01

    A unique simulation technique has been developed capable of modeling electric field induced detection of biomolecules such as viruses, at room temperatures where thermal fluctuations must be considered. The proposed immersed molecular electrokinetic finite element method couples electrokinetics with fluctuating hydrodynamics to study the motion and deformation of flexible objects immersed in a suspending medium under an applied electric field. The force induced on an arbitrary object due to an electric field is calculated based on the continuum electromechanics and the Maxwell stress tensor. The thermal fluctuations are included in the Navier-Stokes fluid equations via the stochastic stress tensor. Dielectrophoretic and fluctuating forces acting on the particle are coupled through the fluid-structure interaction force calculated within the surrounding environment. This method was used to perform concentration and retention efficacy analysis of nanoscale biosensors using gold particles of various sizes. The analysis was also applied to a human papillomavirus.

  15. Effective potentials for 1:1 electrolyte solutions incorporating dielectric saturation and repulsive hydration

    E-print Network

    Effective potentials for 1:1 electrolyte solutions incorporating dielectric saturation and repulsive hydration Philip J. Lenart, Arben Jusufi, and Athanassios Z. Panagiotopoulosa Department Gaussian potential which represents the first hydration shell around the ions. Grand canonical Monte Carlo

  16. 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...

  17. Electrokinetic profiles of nonowoven cotton for absorbent incontinence material

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper discusses recent work on cotton/synthetic nonwovens, their electrokinetic analysis, and their potential use in incontinence materials. Electrokinetic analysis is useful in exploring fiber surface polarity properties, and it is a useful tool to render a snap shot of the role of fiber char...

  18. Effectively incorporating selected multimedia content into medical publications.

    PubMed

    Ziegler, Alexander; Mietchen, Daniel; Faber, Cornelius; von Hausen, Wolfram; Schöbel, Christoph; Sellerer, Markus; Ziegler, Andreas

    2011-01-01

    Until fairly recently, medical publications have been handicapped by being restricted to non-electronic formats, effectively preventing the dissemination of complex audiovisual and three-dimensional data. However, authors and readers could significantly profit from advances in electronic publishing that permit the inclusion of multimedia content directly into an article. For the first time, the de facto gold standard for scientific publishing, the portable document format (PDF), is used here as a platform to embed a video and an audio sequence of patient data into a publication. Fully interactive three-dimensional models of a face and a schematic representation of a human brain are also part of this publication. We discuss the potential of this approach and its impact on the communication of scientific medical data, particularly with regard to electronic and open access publications. Finally, we emphasise how medical teaching can benefit from this new tool and comment on the future of medical publishing. PMID:21329532

  19. Electrokinetic Hydrogen Generation from Liquid WaterMicrojets

    SciTech Connect

    Duffin, Andrew M.; Saykally, Richard J.

    2007-05-31

    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.

  20. High Order WENO Simulation of Electrokinetic Instability in a Cross-Shaped Microchannel

    NASA Astrophysics Data System (ADS)

    Li, Qian; Delorme, Yann; Frankel, Steven

    2013-11-01

    Electroosmotic flow with electrokinetic effects is the primary method of fluid handling in micro-total analysis systems. Knowledge of electrokinetic instabilities (EKI) is required to trigger instabilities in applications like low Reynolds number micromixing or to suppress them in applications such as sample injection, separation and controlled diffusion-limited reaction processes where the minimum sample dispersion is needed. A novel multiblock high order in-house solver based on WENO scheme is applied to simulate the EKI for multiple electrolyte solutions with different electric conductivities in a cross-shaped microchannel. 3D simulations are performed to explore the effects of variations of applied electric field, electric field ratio, and conductivity ratios on the EKI phenomena, and to determine the critical value of electric field required for instabilities. The validity of the numerical study is assessed by comparing the numerical results with the experimental data.

  1. Ion Irradiation Effects in Synthetic Garnets Incorporating Actinides Satoshi Utsunomiya1

    E-print Network

    Utsunomiya, Satoshi

    Ion Irradiation Effects in Synthetic Garnets Incorporating Actinides Satoshi Utsunomiya1 , Lu the long term radiation effects due to radioactive decay can be simulated in short term with heavy ion-irradiation[3], many irradiation experiments using heavy ions have been completed in the potential ceramics

  2. Nonlinear electrokinetic phenomena Induced-charge electro-osmosis (ICEO), induced-charge electrophoresis (ICEP), AC electro-

    E-print Network

    Bazant, Martin Z.

    Nonlinear electrokinetic phenomena Synonyms Induced-charge electro-osmosis (ICEO), induced-charge electrophoresis (ICEP), AC electro- osmosis (ACEO), electro-osmosis of the second kind, electrophoresis a capacitor skin on the surface. Electro-osmosis produces an effective slip of the liquid outside the double

  3. Selective Label-free Electrokinetic Cell Tracker (SELECT): a novel liquid platform for cell characterization

    NASA Astrophysics Data System (ADS)

    Taruvai Kalyana Kumar, Rajeshwari; de Mello Gindri, Izabelle; Kinnamon, David; Kanchustambham, Pradyotha; Rodrigues, Danieli; Prasad, Shalini; BiomaterialsOsseointegration; Novel Engineering Lab Collaboration

    2015-03-01

    Characterization and analysis of rare cells provide critical cues for early diagnosis of diseases. Electrokinetic cell separation has been previously established to have greater efficiency when compared to traditional flow cytometry methods. It has been shown by many researchers that buffer solutions in which cells are suspended in, have enormous effects on producing required dielectrophoretic (DEP) forces to characterize cells. Most commonly used suspension buffers used are deionized water and cell media. However, these solutions exhibit high level of intrinsic noise, which greatly masks the electrokinetic signals from cells under study. Ionic liquids (ILs) show promise towards the creation of conductive fluids with required electrical properties. The goal of this project is to design and test ILs for enhancing DEP forces on cells while creating an environment for preserving their integrity. We analyzed two methylimidazolium based ILs as suspension medium for cell separation. These dicationic ILs possess slight electrical and structural differences with high thermal stability. The two ILs were tested for cytotoxicity using HeLa and bone cells. The effects of electrical neutrality, free charge screening due to ILs towards enhanced electrokinetic signals from cells were studied with improved system resolution and no harmful effects.

  4. Numerical study of dc-biased ac-electrokinetic flow over symmetrical electrodes

    PubMed Central

    Yang Ng, Wee; Ramos, Antonio; Cheong Lam, Yee; Rodriguez, Isabel

    2012-01-01

    This paper presents a numerical study of DC-biased AC-electrokinetic (DC-biased ACEK) flow over a pair of symmetrical electrodes. The flow mechanism is based on a transverse conductivity gradient created through incipient Faradaic reactions occurring at the electrodes when a DC-bias is applied. The DC biased AC electric field acting on this gradient generates a fluid flow in the form of vortexes. To understand more in depth the DC-biased ACEK flow mechanism, a phenomenological model is developed to study the effects of voltage, conductivity ratio, channel width, depth, and aspect ratio on the induced flow characteristics. It was found that flow velocity on the order of mm/s can be produced at higher voltage and conductivity ratio. Such rapid flow velocity is one of the highest reported in microsystems technology using electrokinetics. PMID:22662084

  5. Influence of the finite ion size on the predictions of the standard electrokinetic model: frequency response.

    PubMed

    Aranda-Rascón, M J; Grosse, C; López-García, J J; Horno, J

    2009-08-15

    An extension into the frequency domain of our previous static and stationary works that modify the standard electrokinetic model taking into account the finite size of ions in the electrolyte solution [J.J. López-García, M.J. Aranda-Rascón, J. Horno, J. Colloid Interface Sci. 316 (2007) 196; J.J. López-García, M.J. Aranda-Rascón, J. Horno, J. Colloid Interface Sci. 323 (2008) 146; M.J. Aranda-Rascón, C. Grosse, J.J. López-García, J. Horno, J. Colloid Interface Sci., in press] is presented. It is shown that the excluded volume effect can be quite substantial in some cases and is not negligible even for weakly charged particles. Furthermore, it generally improves on the predictions of the standard electrokinetic model since the low-frequency dielectric and conductivity increments as well as the electrophoretic mobility increase with the ion size. PMID:19464016

  6. A method of producing electrokinetic power through forward osmosis

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  7. Treatment of sewage sludge using electrokinetic geosynthetics.

    PubMed

    Glendinning, Stephanie; Lamont-Black, John; Jones, Colin J F P

    2007-01-31

    The treatment and disposal of sewage sludge is one of the most problematical issues affecting wastewater treatment in the developed world. The traditional outlets for sewage sludge are to spread it on agricultural land, or to form a cake for deposit to landfill or incineration. In order to create a sludge cake, water must be removed. Existing dewatering technology based on pressure can only remove a very limited amount of this water because of the way in which water is bound to the sludge particles or flocs. Several researchers have shown that electrokinetic dewatering of sludge is more efficient than conventional hydraulically driven methods. This involves the application of a dc voltage across the sludge, driving water under an electrical gradient from positive (anode) electrode to negative (cathode) electrode. However, there have been several reasons why this technique has not been adopted in practice, not least because the, normally metallic, anode rapidly dissolves due to the acidic environment created by the electrolysis of water. This paper will describe experimentation using electrokinetic geosynthetics (EKG): polymer-based materials containing conducting elements. These have been used to minimise the problem of electrode corrosion and create a sludge treatment system that can produce dry solids contents in excess of 30%. It will suggest different options for the treatment of sludges both in situ in sludge lagoons and windrows, and ex situ as a treatment process. PMID:16635546

  8. Selenium incorporation into calcite and its effect on crystal growth: An atomic force microscopy study

    E-print Network

    Montes-Hernandez, German

    Selenium incorporation into calcite and its effect on crystal growth: An atomic force microscopy December 2012 Available online 7 January 2013 Editor: J. Fein Keywords: Calcite Atomic force microscopy Crystal growth Selenium The atomic processes leading to calcite growth are still debated. The presence

  9. Effects of arsenic incorporation on jarosite dissolution rates and reaction products

    E-print Network

    Hu, Qinhong "Max"

    Effects of arsenic incorporation on jarosite dissolution rates and reaction products Matthew R 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

  10. Effects of mechanical removal and incorporation of post-harvest residue on ratoon sugarcane yields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two studies were conducted to determine the effects of post-harvest residue management in conjunction with incorporation on sugarcane grown on heavy-textured soils in the high rainfall climate of Louisiana. For the first experiment, whole-plots consisted of full retention, complete removal by burnin...

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

    E-print Network

    Gilchrist, James F.

    Nitrogen incorporation effects on gain properties of GaInNAs lasers: Experiment and theory A April 2005; published online 12 May 2005 Gain properties of GaInNAs lasers with different nitrogen concentrations in the quantum wells are investigated experimentally and theoretically. Whereas nitrogen

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

    ERIC Educational Resources Information Center

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

    2008-01-01

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

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

    ERIC Educational Resources Information Center

    Hodge, David R.

    2011-01-01

    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…

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

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  15. Multiconfigurational nuclear-electronic orbital approach: Incorporation of nuclear quantum effects in electronic structure calculations

    E-print Network

    Hammes-Schiffer, Sharon

    Multiconfigurational nuclear-electronic orbital approach: Incorporation of nuclear quantum effects 26 March 2002; accepted 30 May 2002 The nuclear-electronic orbital NEO method for the calculation of mixed nuclear-electronic wave functions is presented. Both electronic and nuclear molecular orbitals

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

    PubMed

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

    2012-10-01

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

  17. Electrokinetic remediation of manganese and ammonia nitrogen from electrolytic manganese residue.

    PubMed

    Shu, Jiancheng; Liu, Renlong; Liu, Zuohua; Du, Jun; Tao, Changyuan

    2015-10-01

    Electrolytic manganese residue (EMR) is a solid waste found in filters after sulphuric acid leaching of manganese carbonate ore, which mainly contains manganese and ammonia nitrogen and seriously damages the ecological environment. This work demonstrated the use of electrokinetic (EK) remediation to remove ammonia nitrogen and manganese from EMR. The transport behavior of manganese and ammonia nitrogen from EMR during electrokinetics, Mn fractionation before and after EK treatment, the relationship between Mn fractionation and transport behavior, as well as the effects of electrolyte and pretreatment solutions on removal efficiency and energy consumption were investigated. The results indicated that the use of H2SO4 and Na2SO4 as electrolytes and pretreatment of EMR with citric acid and KCl can reduce energy consumption, and the removal efficiencies of manganese and ammonia nitrogen were 27.5 and 94.1 %, respectively. In these systems, electromigration and electroosmosis were the main mechanisms of manganese and ammonia nitrogen transport. Moreover, ammonia nitrogen in EMR reached the regulated level, and the concentration of manganese in EMR could be reduced from 455 to 37 mg/L. In general, the electrokinetic remediation of EMR is a promising technology in the future. PMID:26062467

  18. Electrokinetics of pH-regulated zwitterionic polyelectrolyte nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  19. Recent Advances in the Use of Electrokinetic Self-Potential Signals as an Effective Tool in Hydrogeophysics to Monitor Ground Water Flow

    NASA Astrophysics Data System (ADS)

    Revil, A.; Suski, B.; Rizzo, E.; Naudet, V.

    2003-12-01

    Ground water flow generates detectable electrical signals at the ground surface through a conversion mechanism called streaming potential. These signals can be recorded in a passive way with a set of non-polarizable electrodes and a multi-electrode digital multimeter. These signals can be inverted to image the shape of the water table and its temporal variations using new self-potential tomography (SPT) algorithms. The signal-to-noise ratio seems high enough to expect an accuracy of 10 cm in the detrmination of the depth of the water table. Then, because the sensors are cheap, we can use an important number of measurement stations and we can obtain a great amount of information to invert in a cost-effective way. In this talk, we will discuss the physics of this hydro-electric and present both forward and backward methods to interpret field data. We will show examples from three field studies in which self-potential signals are associated with hydraulic head fluctuations. We will discuss the stability of the electrodes, the sources of noise, and new challenges in combining SPT with more classical electrical resistivity tomography (ERT).

  20. Method and apparatus for electrokinetic transport

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    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.

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

    USGS Publications Warehouse

    Thorn, Kevin A.; Cox, Larry G.

    2012-01-01

    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.

  2. Geochemical assessment of metal transport in glacial till during electrokinetic remediation.

    PubMed

    Al-Hamdan, Ashraf Z; Reddy, Krishna R

    2008-04-01

    This paper presents the chemical speciation and retention behavior of chromium (Cr), nickel (Ni), and cadmium (Cd) prior to and after the electrokinetic remediation in glacial till soil. The speciation of the metals was predicted using the chemical speciation program MINEQL(+). The simulations were performed for single-contaminant with only Cr(VI) or Ni, and multi-contaminants consisting of: (1) Cr(VI), Ni, and Cd; (2) Cr(III), Ni and Cd; (3) Cr(VI), Cr(III), Ni and Cd; (4) Cr(VI), Ni, and Cd with reducing agents; and (5) Cr(III), Ni, and Cd with oxidizing agent (Mn). The results showed that the speciation and distribution of cationic metals [Ni, Cd, and Cr(III)] in glacial till soil remain unaffected or slightly affected during electrokinetics. This is attributed to the high pH buffering capacity of the glacial till, leading the metals to precipitate in the soil prior to and after electrokinetics. This study showed that during electrokinetics, Cr(VI) existed as anionic complex and migrated towards the anode and the migration is maximum in case of a single-contaminant system. The study also showed that near the anode in the absence of any reducing and oxidizing agent, Cr(VI) mostly adsorbed, and some of Cr(VI) reduced to Cr(III) and migrated towards the cathode and finally precipitated due to high pH conditions. Ni and Cd remain adsorbed or precipitated due to the high pH conditions throughout the soil. Among the reducing agents, the sulfide had significant effect on the migration of metals compared to ferrous ions. While in the presence of oxidizing agent (Mn), no noticeable Cr(VI) was found in the soil sample indicating the reduction of Cr(VI) to Cr(III) and the predominance of reducing conditions due to the presence of naturally occurring iron in the glacial till soil. Overall, this study provides a reasonable explanation of the speciation and distribution of chromium, nickel and cadmium during the electrokinetic remediation of glacial till soil. PMID:17682832

  3. Effect of silver nanoparticles incorporation on viscoelastic properties of acrylic resin denture base material

    PubMed Central

    Mahross, Hamada Zaki; Baroudi, Kusai

    2015-01-01

    Objective: The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporation on viscoelastic properties of acrylic resin denture base material. Materials and Methods: A total of 20 specimens (60 × 10 × 2 mm) of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without additives (control group). The dynamic viscoelastic test for the test specimens was performed using the computerized material testing system. The resulting deflection curves were analyzed by material testing software NEXYGEN MT. Results: The 5% nanoparticles of silver (NAg) had significantly highest mean storage modulus E’ and loss tangent Tan ? values followed by 2% NAg (P < 0.05). For 1% nanosilver incorporation (group B), there were no statistically significant differences in storage modulus E’, lost modulus E” or loss tangent Tan ? with other groups (P > 0.05). Conclusion: The AgNPs incorporation within the acrylic denture base material can improve its viscoelastic properties. PMID:26038651

  4. Journal of Chromatography A, 807 (1998) 111119 Microemulsion electrokinetic chromatography of fatty acids as

    E-print Network

    Miksik, Ivan

    1998-01-01

    Journal of Chromatography A, 807 (1998) 111­119 Microemulsion electrokinetic chromatography by microemulsion electrokinetic chromatography. Separations were done by using an untreated fused-silica capillary/w) and n-butanol (6.55%, w/w), pH 10.2. Separation by microemulsion electrokinetic chromatography

  5. Charged colloids and polyelectrolytes: from statics to electrokinetics

    NASA Astrophysics Data System (ADS)

    Löwen, H.; Esztermann, A.; Wysocki, A.; Allahyarov, E.; Messina, R.; Jusufi, A.; Hoffmann, N.; Gottwald, D.; Kahl, G.; Konieczny, M.; Likos, C. N.

    2005-01-01

    A review is given on recent studies of charged colloidal suspensions and polyelectrolytes both in static and non-equilibrium situations. As far as static equilibrium situations are concerned, we discuss three different problems: 1) Sedimentation density profiles in charged suspensions are shown to exhibit a stretched non-bariometric wing at large heights and binary suspensions under gravity can exhibit an analog of the brazil-nut effect known from granular matter, i.e. the heavier particles settle on top of the lighter ones. 2) Soft polyelectrolyte systems like polyelectrolyte stars and microgels show an ultra-soft effective interaction and this results into an unusual equilibrium phase diagram including reentrant melting transitions and stable open crystalline lattices. 3) The freezing transition in bilayers of confined charged suspensions is discussed and a reentrant behaviour is obtained. As far as nonequilibrium problems are concerned, we discuss an interface instability in oppositely driven colloidal mixtures and discuss possible approaches to simulate electrokinetic effects in charged suspensions.

  6. Electrokinetic demonstration at the unlined chromic acid pit

    SciTech Connect

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

    1998-01-01

    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.

  7. Electrokinetically modulated peristaltic transport of power-law fluids.

    PubMed

    Goswami, Prakash; Chakraborty, Jeevanjyoti; Bandopadhyay, Aditya; Chakraborty, Suman

    2016-01-01

    The electrokinetically modulated peristaltic transport of power-law fluids through a narrow confinement in the form of a deformable tube is investigated. The fluid is considered to be divided into two regions - a non-Newtonian core region (described by the power-law behavior) which is surrounded by a thin wall-adhering layer of Newtonian fluid. This division mimics the occurrence of a wall-adjacent cell-free skimming layer in blood samples typically handled in microfluidic transport. The pumping characteristics and the trapping of the fluid bolus are studied by considering the effect of fluid viscosities, power-law index and electroosmosis. It is found that the zero-flow pressure rise is strongly dependent on the relative viscosity ratio of the near-wall depleted fluid and the core fluid as well as on the power-law index. The effect of electroosmosis on the pressure rise is strongly manifested at lower occlusion values, thereby indicating its importance in transport modulation for weakly peristaltic flow. It is also established that the phenomenon of trapping may be controlled on-the-fly by tuning the magnitude of the electric field: the trapping vanishes as the magnitude of the electric field is increased. Similarly, the phenomenon of reflux is shown to disappear due to the action of the applied electric field. These findings may be applied for the modulation of pumping in bio-physical environments by means of external electric fields. PMID:26524260

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

    SciTech Connect

    Jolly Bose, R.; Kumar, R. Vinod; Sudheer, S. K.; Mahadevan Pillai, V. P.; Reddy, V. R.; Ganesan, V.

    2012-12-01

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

  9. General electrokinetic model for concentrated suspensions in aqueous electrolyte solutions: Electrophoretic mobility and electrical conductivity in static electric fields.

    PubMed

    Carrique, Félix; Ruiz-Reina, Emilio; Roa, Rafael; Arroyo, Francisco J; Delgado, Ángel V

    2015-10-01

    In recent years different electrokinetic cell models for concentrated colloidal suspensions in aqueous electrolyte solutions have been developed. They share some of its premises with the standard electrokinetic model for dilute colloidal suspensions, in particular, neglecting both the specific role of the so-called added counterions (i.e., those released by the particles to the solution as they get charged), and the realistic chemistry of the aqueous solution on such electrokinetic phenomena as electrophoresis and electrical conductivity. These assumptions, while having been accepted for dilute conditions (volume fractions of solids well below 1%, say), are now questioned when dealing with concentrated suspensions. In this work, we present a general electrokinetic cell model for such kind of systems, including the mentioned effects, and we also carry out a comparative study with the standard treatment (the standard solution only contains the ions that one purposely adds, without ionic contributions from particle charging or water chemistry). We also consider an intermediate model that neglects the realistic aqueous chemistry of the solution but accounts for the correct contribution of the added counterions. The results show the limits of applicability of the classical assumptions and allow one to better understand the relative role of the added counterions and ions stemming from the electrolyte in a realistic aqueous solution, on electrokinetic properties. For example, at low salt concentrations the realistic effects of the aqueous solution are the dominant ones, while as salt concentration is increased, it is this that progressively takes the control of the electrokinetic response for low to moderate volume fractions. As expected, if the solids concentration is high enough the added counterions will play the dominant role (more important the higher the particle surface charge), no matter the salt concentration if it is not too high. We hope this work can help in setting up the real limits of applicability of the standard cell model for concentrated suspensions by a quantitative analysis of the different effects that have been classically disregarded, showing that in many cases they can be determinant to get rigorous predictions. PMID:26051031

  10. Determination of food colorants by microemulsion electrokinetic chromatography.

    PubMed

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

    2005-02-01

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

  11. Self-consistent problem of induced polarization of electrokinetic origin

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

  12. Electrokinetic particle-electrode interactions at high frequencies

    NASA Astrophysics Data System (ADS)

    Yariv, Ehud; Schnitzer, Ory

    2013-01-01

    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.

  13. Compositional and Surface Effects of Bismuth Incorporation in GaSb Films

    NASA Astrophysics Data System (ADS)

    Tait, C. Ryan; Duzik, Adam; Millunchick, Joanna

    2014-03-01

    III-V-Bi semiconductor films represent a new class of highly mismatched alloys that exhibit interesting properties including large reduction in band gap, giant spin orbit bowing, and preserved electron mobility at the expense of hole mobility. These compounds have proven difficult to grow with most results coming from experimentation with GaAsBi with little known regarding GaSbBi. Various growth conditions were tested for GaSbBi and characterized with scanning electron microscopy, x-ray diffraction, and Rutherford backscattering spectroscopy. The films demonstrate Bi concentrations of up to 12% with as low as 3% droplet coverage. Surface Bi and Ga droplet morphology was shown to be dependent on relative flux ratios of Ga, Sb, and Bi and independent of film growth rate. Additionally it is found that As incorporates into the films with no intentional source and the incorporation being dependent on Bi incorporation. This effect is identified as an auto-compensation mechanism for the strain induced from the introduction of Bi.

  14. Effect of lead fluoride incorporation on the structure and luminescence properties of tungsten sodium phosphate glasses

    NASA Astrophysics Data System (ADS)

    Nardi, Rachel Prado Russo Delorenzo; Braz, Celso Eduardo; de Camargo, Andrea S. S.; Ribeiro, Sidney J. L.; Rocha, Lucas A.; Cassanjes, Fábia Castro; Poirier, Gael

    2015-11-01

    Tungsten phosphate glasses are known to be promising materials for several applications in optics such as non linear optical properties, lower phonon energy or photochromic effects related with tungsten oxide incorporation inside the phosphate network. In this study, lead fluoride has been incorporated in a 60NaPO3-40WO3 glass composition according to the ternary molar compositions (100 - x)[0.6NaPO3-0.4WO3]-xPbF2 with x varying from 0 to 60 mol%. The structural changes as a function of composition were investigated by thermal analysis, UV-visible absorption, Raman spectroscopy, X-ray diffraction of the crystallized samples, and Eu3+ emission in the visible. While DSC analyzes points out a strong decrease in the glass network connectivity and higher crystallization tendency with increasing PbF2 contents, Raman spectra clearly identify a progressive incorporation of PbF2 in the phosphate network with the formation of terminal Psbnd F and Wsbnd F bonds. These results are also in agreement with the crystallization of ?-PbF2 observed for the most lead fluoride concentrated samples. Investigation of Eu3+ emission data in the visible showed longer 5D0 excited state lifetime values and higher quantum efficiencies. These results are discussed in terms of the assumption of higher local symmetry around Eu3+ with increasing PbF2 contents.

  15. Incorporating cost-effectiveness data in a fair process for priority setting efforts

    PubMed Central

    Youngkong, Sitaporn

    2015-01-01

    Cost-effectiveness data is useful for use in priority setting decisions in order to improve the efficiency of resources used. This paper thereby responds to Eckard et al. which addressed the use of cost-effectiveness data in the actual prioritization decisions in the Swedish national clinical guidelines for heart diseases. Based on a set of experiences on the use of economic evaluation in priority setting processes, this paper emphasizes the potential approach to incorporating cost-effectiveness data in the prioritization process to enhance transparency of the decisions, and highlights the importance of designing a fair decision-making process that can enforce the sustained implementation of cost-effectiveness data. PMID:26188814

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  17. Effects of Incorporating Carboxymethyl Chitosan into PMMA Bone Cement Containing Methotrexate

    PubMed Central

    Liu, Bo-Ming; Li, Ming; Yin, Bao-Sheng; Zou, Ji-Yang; Zhang, Wei-Guo; Wang, Shou-Yu

    2015-01-01

    Treatment of bone metastases usually includes surgical resection with local filling of methotrexate (MTX) in polymethyl methacrylate (PMMA) cement. We investigated whether incorporating carboxymethyl chitosan (CMCS) in MTX-PMMA cement might overcome disadvantages associated with MTX. To determine the optimal CMCS+MTX concentration to suppress the viability of cancer cells, an integrated microfluidic chip culturing highly metastatic lung cancer cells (H460) was employed. The mechanical properties, microstructure, and MTX release of (CMCS+MTX)-PMMA cement were evaluated respectively by universal mechanical testing machine, scanning electron microscopy (SEM), and incubation in simulated body fluid with subsequent HPLC-MS. Implants of MTX-PMMA and (CMCS+MTX)-PMMA cement were evaluated in vivo in guinea pig femurs over time using spiral computed tomography with three-dimensional image reconstruction, and SEM at 6 months. Viability of H460 cells was significantly lowest after treatment with 57 ?g/mL CMCS + 21 ?g/mL MTX, which was thus used in subsequent experiments. Incorporation of 1.6% (w/w) CMCS to MTX-PMMA significantly increased the bending modulus, bending strength, and compressive strength by 5, 2.8, and 5.2%, respectively, confirmed by improved microstructural homogeneity. Incorporation of CMCS delayed the time-to-plateau of MTX release by 2 days, but increased the fraction released at the plateau from 3.24% (MTX-PMMA) to 5.34%. Relative to the controls, the (CMCS+MTX)-PMMA implants integrated better with the host bone. SEM revealed pores in the cement of the (CMCS+MTX)-PMMA implants that were not obvious in the controls. In conclusion, incorporation of CMCS in MTX-PMMA appears a feasible and effective modification for improving the anti-tumor properties of MTX-PMMA cement. PMID:26657526

  18. Effects of Incorporating Carboxymethyl Chitosan into PMMA Bone Cement Containing Methotrexate.

    PubMed

    Liu, Bo-Ming; Li, Ming; Yin, Bao-Sheng; Zou, Ji-Yang; Zhang, Wei-Guo; Wang, Shou-Yu

    2015-01-01

    Treatment of bone metastases usually includes surgical resection with local filling of methotrexate (MTX) in polymethyl methacrylate (PMMA) cement. We investigated whether incorporating carboxymethyl chitosan (CMCS) in MTX-PMMA cement might overcome disadvantages associated with MTX. To determine the optimal CMCS+MTX concentration to suppress the viability of cancer cells, an integrated microfluidic chip culturing highly metastatic lung cancer cells (H460) was employed. The mechanical properties, microstructure, and MTX release of (CMCS+MTX)-PMMA cement were evaluated respectively by universal mechanical testing machine, scanning electron microscopy (SEM), and incubation in simulated body fluid with subsequent HPLC-MS. Implants of MTX-PMMA and (CMCS+MTX)-PMMA cement were evaluated in vivo in guinea pig femurs over time using spiral computed tomography with three-dimensional image reconstruction, and SEM at 6 months. Viability of H460 cells was significantly lowest after treatment with 57 ?g/mL CMCS + 21 ?g/mL MTX, which was thus used in subsequent experiments. Incorporation of 1.6% (w/w) CMCS to MTX-PMMA significantly increased the bending modulus, bending strength, and compressive strength by 5, 2.8, and 5.2%, respectively, confirmed by improved microstructural homogeneity. Incorporation of CMCS delayed the time-to-plateau of MTX release by 2 days, but increased the fraction released at the plateau from 3.24% (MTX-PMMA) to 5.34%. Relative to the controls, the (CMCS+MTX)-PMMA implants integrated better with the host bone. SEM revealed pores in the cement of the (CMCS+MTX)-PMMA implants that were not obvious in the controls. In conclusion, incorporation of CMCS in MTX-PMMA appears a feasible and effective modification for improving the anti-tumor properties of MTX-PMMA cement. PMID:26657526

  19. Method for eliminating gas blocking in electrokinetic pumping systems

    DOEpatents

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

    2001-09-11

    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.

  20. Improving the Power Conversion Efficiency of Ultrathin Organic Solar Cells by Incorporating Plasmonic Effects of Spheroidal Metallic Nanoparticles

    E-print Network

    Park, Namkyoo

    Improving the Power Conversion Efficiency of Ultrathin Organic Solar Cells by Incorporating be exploited to achieve efficient harvesting of solar energy. Notably, the incorporation of plasmonic effects can allow the light harvesting capability of a solar cell to be maintained even as the thickness

  1. Effects of Pt incorporation on the isothermal oxidation behavior of chemical vapor deposition aluminide coatings

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Haynes, J. A.; Wright, G.; Pint, B. A.; Cooley, K. M.; Lee, W. Y.; Liaw, P. K.

    2001-07-01

    The effects of Pt incorporation on the isothermal oxidation and diffusion behavior of low-sulfur aluminide bond coatings were investigated. Aluminide (NiAl) coatings and Pt-modified aluminide (Ni,Pt)Al coatings were synthesized on a low-sulfur, yttrium-free single-crystal Ni-based superalloy by a high-purity, low-activity chemical vapor deposition (CVD) aluminizing procedure. The isothermal oxidation kinetics and scale adhesion behavior of CVD NiAl and (Ni,Pt)Al coatings before and after isothermal oxidation were determined by electron microprobe analysis. Platinum did not reduce oxide-scale growth kinetics. No significant differences in bulk refractory metal (W, Ta, Re, and Mo) distributions were observed as a result of Pt incorporation. Spallation of the alumina scale and the formation of large voids along the oxide-metal interface were commonly observed over the NiAl coating grain boundaries after 100 hours at 1150 °C. In contrast, no spallation of Al2O3 scales occurred on (Ni,Pt)Al coating surfaces or grain boundaries, although the sulfur content in the CVD (Ni,Pt)Al coatings was higher than that of the CVD NiAl coatings. Most significantly, no voids were observed at the oxide-metal interface on (Ni,Pt)Al coating surfaces or cross sections after 200 hours at 1150 °C. It was concluded that a major beneficial effect of Pt incorporation on an aluminide coatings oxidation resistance is the elimination of void growth at the oxide-metal interface, likely by mitigation of detrimental sulfur effects.

  2. Incorporation of solvation effects into the fragment molecular orbital calculations with the Poisson-Boltzmann equation

    NASA Astrophysics Data System (ADS)

    Watanabe, Hirofumi; Okiyama, Yoshio; Nakano, Tatsuya; Tanaka, Shigenori

    2010-11-01

    We developed FMO-PB method, which incorporates solvation effects into the Fragment Molecular Orbital calculation with the Poisson-Boltzmann equation. This method retains good accuracy in energy calculations with reduced computational time. We calculated the solvation free energies for polyalanines, Alpha-1 peptide, tryptophan cage, and complex of estrogen receptor and 17 ?-estradiol to show the applicability of this method for practical systems. From the calculated results, it has been confirmed that the FMO-PB method is useful for large biomolecules in solution. We also discussed the electric charges which are used in solving the Poisson-Boltzmann equation.

  3. Fast Myoglobin Detection Using Nanofluidic Electrokinetic Trapping Technique

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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.

  4. Generalization of electromagnetic scattering by charged grains through incorporation of interband and intraband effects.

    PubMed

    Kla?ka, Jozef; Kocifaj, Miroslav; Kundracik, František; Videen, Gorden; Kohút, Igor

    2015-11-01

    Scattering of electromagnetic radiation by electrically charged spherical particles is treated theoretically. A generalization of the approach is performed by incorporating both intraband and interband effects, while a new oscillatory term corresponding to the classical dispersion theory and the semi-quantum approach is considered. It is shown through a set of numerical experiments that interband effects may reduce the amplitude of resonant peaks for scattering, Qsca, and absorption, Qabs, and cause a shift of peak positions to longer wavelengths. In general, the resonant features due to interband and intraband effects can occur at different frequencies; thus, both together may result in qualitatively and quantitatively new optical signatures of electrically charged particles. This is a motivating factor for experimentalists who can use the particles as targeted probes, for example, in mapping the electric fields in different media based on scattering and/or absorption properties of electrified particulate systems. PMID:26512521

  5. Electrokinetic flow in a nanochannel with an overlapped electrical double layer

    NASA Astrophysics Data System (ADS)

    Song, Zhuorui

    Electrokinetic flows within an overlapped Electrical Double Layer (EDL), which are not well-understood, were theoretically investigated in this study with the particular attention on the consideration of hydronium ions in the EDL. Theoretical models for fully-developed steady pressure-driven flow for salt-free water or a binary salt solution in a slit-like nanochannel connecting to two reservoirs were developed. The transient flow in such a domain was also simulated from static state to the final steady state. In these models, the Poisson equation and the Nernst-Planck equation were solved either by analytic methods or by the finite element method. Surface adsorption-desorption equilibrium and water equilibrium were considered to account for the proton exchange at the surface and in the fluid. These models were the first to include those comprehensive processes that are uniquely important for overlapped EDL scenarios. This study improves the understanding of electrokinetic flows within an overlapped EDL by demonstrating the profound impact of hydronium ions on the EDL structure. In the steady flow of potassium chloride solutions, hydronium ions are more enriched than potassium ions by up to 2~3 orders of magnitude, making the electrokinetic effects greatly depressed. The unequal enrichment effects of counterions were omitted in the traditional theory partially because the transient is extremely slow. The simulation results show that a concentration hump of hydronium ions initially forming at the channel entrance gradually expands over the whole channel in a way similar to the concentration plug flow moving downstream. The time required for the flow to reach the steady state could be as long as thousands of times the hydraulic retention time, dependent on the degree of the EDL overlap. This study improves the fundamental understanding for nanofluidic flows.

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

    SciTech Connect

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

    1990-01-01

    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.

  7. Effect of free cholesterol on incorporation of triolein in phospholipid bilayers

    SciTech Connect

    Spooner, P.J.R.; Small, D.M.

    1987-09-08

    Triacylglycerols are the major substrates for lipolytic enzymes that act at the surface of emulsion-like particles such as triglyceride-rich lipoproteins, chylomicrons, and intracellular lipid droplets. This study examines the effect of cholesterol on the solubility of a triacylglycerol, triolein, in phospholipid surfaces. Solubilities of (carbonyl-/sup 13/C) triolein in phospholipid bilayer vesicles containing between 0 and 50 mol % free cholesterol, prepared by cosonication, were measured by /sup 13/C NMR. The carbonyl resonances from bilayer-incorporated triglyceride were shifted downfield in the /sup 13/C NMR spectra from those corresponding to excess, nonincorporated material. This enabled solubilities to be determined directly from carbonyl peak intensities at most cholesterol concentration. The bilayer solubility of triolein was inversely proportional to the cholesterol/phospholipid mole ratio. In pure phospholipid vesicles the triolein solubility was 2.2 mol %. The triglyceride incorporation decreased to 1.1 mol % at a cholesterol/phospholipid mole ratio of 0.5, and at a mole ratio of 1.0 for the bilayer lipids, the triolein solubility was reduced to just 0.15 mol %. The effects of free cholesterol were more pronounced and progressive than observed previously on the bilayer solubility of cholestery oleate. As with cholesteryl oleate, they suggest that cholesterol also displaces solubilized triglyceride to deeper regions of the bilayer.

  8. Effective supercontinuum generation by using highly nonlinear dispersion-shifted fiber incorporated with Si nanocrystals.

    PubMed

    Jeong, Seongmook; Ju, Seongmin; Kim, Youngwoong; Watekar, Pramod R; Jeong, Hyejeong; Lee, Ho-Jae; Boo, Seongjae; Kim, Dug Young; Han, Won-Taek

    2012-01-01

    The dispersion-shifted fiber (DSF) incorporated with Si nanocrystals (Si-NCs) having highly nonlinear optical property was fabricated to investigate the effective supercontinuum generation characteristics by using the MCVD process and the drawing process. Optical nonlinearity was enhanced by incorporating Si nanocrystals in the core of the fiber and the refractive index profile of a dispersion-shifted fiber was employed to match its zero-dispersion wavelength to that of the commercially available pumping source for generating effective supercontinuum. The non-resonant nonlinear refractive index, n2, of the Si-NCs doped DSF measured by the cw-SPM method was measured to be 7.03 x 10(-20) [m2/W] and the coefficient of non-resonant nonlinearity, gamma, was 7.14 [W(-1) km(-1)]. To examine supercontinuum generation of the Si-NCs doped DSF, the femtosecond fiber laser with the pulse width of 150 fs (at 1560 nm) was launched into the fiber core. The output spectrum of the Si-NCs doped DSF was found to broaden from 1300 nm to wavelength well beyond 1700 nm, which can be attributed to the enhanced optical nonlinearity by Si-NCs embedded in the fiber core. The short wavelength of the supercontinuum spectrum in the Si-NCs doped DSF showed shift from 1352 nm to 1220 nm for the fiber length of 2.5 m and 200 m, respectively. PMID:22524002

  9. Incorporation of quercetin in lipid microparticles: effect on photo- and chemical-stability.

    PubMed

    Scalia, Santo; Mezzena, Matteo

    2009-01-15

    Lipid microparticles loaded with the flavonoid, quercetin were developed in order to enhance its stability in topical formulations. The microparticles were produced using tristearin as the lipid material and phosphatidylcholine as the emulsifier. The obtained lipoparticles were characterized by release studies, scanning electron microscopy and powder X-ray diffractometry. The quercetin loading was 12.1% (w/w). Free or microencapsulated quercetin was introduced in a model cream formulation (oil-in-water emulsion) and irradiated with a solar simulator. The extent of photodegradation was measured by high-performance liquid chromatography. The light-induced decomposition of quercetin in the cream vehicle was markedly decreased by incorporation into the lipid microparticles (the extent of degradation was 23.1+/-3.6% for non-encapsulated quercetin compared to 11.9+/-2.5% for the quercetin-loaded microparticles) and this photostabilization effect was maintained over time. Moreover, the chemical instability of quercetin, during 3-month storage of the formulations at room temperature and in the dark, was almost completely suppressed by the lipid microparticle system. Therefore incorporation of quercetin in lipoparticles represents an effective strategy to enhance its stability in dermatological products. PMID:19042102

  10. Effect of Low-Level Laser Therapy on Incorporation of Block Allografts

    PubMed Central

    Valiati, Renato; Paes, Jefferson Viapiana; de Moraes, Aury Nunes; Gava, Aldo; Agostini, Michelle; Masiero, Anelise Viapiana; de Oliveira, Marilia Gerhardt; Pagnoncelli, Rogério Miranda

    2012-01-01

    Objective To assess the effect of low-level laser therapy (LLLT) on the incorporation of deep-frozen block allografts in a rabbit model. Background Data Studies have shown that LLLT has beneficial effects on tissue repair and new bone formation. Methods Bone tissue was harvested from two rabbits, processed by deep-freezing and grafted into the calvaria of 12 animals, which were then randomly allocated into two groups: experimental (L) and control (C). Rabbits in group L were irradiated with an aluminum gallium arsenide diode laser (AlGaAs; wavelength 830 nm, 4 J/cm2), applied to four sites on the calvaria, for a total dose of 16 J/cm2 per session. The total treatment dose after eight sessions was 128 J/cm2. Animals were euthanized at 35 (n = 6) or 70 days (n = 6) postoperatively. Results Deep-freeze-processed block allografts followed by LLLT showed incorporation at the graft-host interface, moderate bone remodeling, partial filling of osteocyte lacunae, less inflammatory infiltrate in the early postoperative period, and higher collagen deposition than the control group. Conclusion Optical microscopy and scanning electron microscopy showed that allograft bone processed by deep-freezing plus LLLT is suitable as an alternative for the treatment of bone defects. Use of the deep-freezing method for processing of bone grafts preserves the structural and osteoconductive characteristics of bone tissue. PMID:23155359

  11. Incorporating partial shining effects in proton pencil-beam dose calculation.

    PubMed

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

    2008-02-01

    A range modulator wheel (RMW) is an essential component in passively scattered proton therapy. We have observed that a proton beam spot may shine on multiple steps of the RMW. Proton dose calculation algorithms normally do not consider the partial shining effect, and thus overestimate the dose at the proximal shoulder of spread-out Bragg peak (SOBP) compared with the measurement. If the SOBP is adjusted to better fit the plateau region, the entrance dose is likely to be underestimated. In this work, we developed an algorithm that can be used to model this effect and to allow for dose calculations that better fit the measured SOBP. First, a set of apparent modulator weights was calculated without considering partial shining. Next, protons spilled from the accelerator reaching the modulator wheel were simplified as a circular spot of uniform intensity. A weight-splitting process was then performed to generate a set of effective modulator weights with the partial shining effect incorporated. The SOBPs of eight options, which are used to label different combinations of proton-beam energy and scattering devices, were calculated with the generated effective weights. Our algorithm fitted the measured SOBP at the proximal and entrance regions much better than the ones without considering partial shining effect for all SOBPs of the eight options. In a prostate patient, we found that dose calculation without considering partial shining effect underestimated the femoral head and skin dose. PMID:18199905

  12. Transient electrokinetic response of finely layered, fluid-filled porous media

    NASA Astrophysics Data System (ADS)

    Dietrich, M.; Delprat-Jannaud, F.; Garambois, S.

    2012-04-01

    Transient electrokinetic coupling phenomena created at the microscopic scale by the passage of seismic waves through fluid-saturated porous media generate conversions between seismic and electromagnetic (EM) energy which can be observed at the macroscopic scale. Far from being a mere scientific curiosity, transient seismoelectric or electroseismic phenomena are especially appealing to oil and gas exploration and hydrogeology as they open up the (fairly unique) possibility to characterize fluid-bearing geological formations with the resolution of seismic methods. Indeed, electrokinetic effects are likely to reconcile the sensitivity of electromagnetic exploration methods to fluids with the high resolving power of seismic prospecting techniques for structural imaging, thus naturally bridging the gap between these two important geophysical investigation means. Accounting for the electromagnetic dimension of the seismic wave propagation, or conversely, accounting for the seismic dimension of electromagnetic wave propagation gives new insights into the microstructure and physico-chemistry of fluid-filled porous or fractured media. We present full-waveform simulations of the coupled seismoelectromagnetic wave propagation in fluid-saturated, finely stratified porous media of interest to oil and gas exploration. Our simulation code uses the macroscopic governing equations derived by Pride [1994], which couple Biot's theory and Maxwell equations via flux/force transport equations. The synthetic seismoelectrograms and seismomagnetrograms are computed by extending the generalized reflection and transmission matrix method and by using a discrete wave number integration of the global reflectivity obtained in the frequency wave number domain. The theoretical signals clearly display the coseismic electric and magnetic fields travelling with the seismic disturbances as well as the seismic-to-electromagnetic conversions taking place at contrasts in solid and fluid properties. Our computer code also allows us to compute partial solutions to the full response, notably plane-wave solutions, and solutions in which particular wave conversions or multiple reflections are cancelled. Gradients of properties are simulated by considering stacks of thin layers. We first investigate the sensitivity of the electrokinetic response to the mechanical and electrical properties of thin layers whose thickness is on the order of 1/20th of the incident seismic wavelength. Unlike seismic measurements, seismo-electromagnetic signals are shown to be sensitive to very thin heterogeneities, therefore yielding a "super-resolution" of the probed structures. Next, we consider stacks of thin strata representing a sandstone hydrocarbon reservoir in order to study its response to various water, oil and gas saturations including the capillary effects. These simulations underline the potential of electrokinetic conversions to improve the characterization of fluid-filled porous rock formations.

  13. Effect of incorporation of ethylene glycol into PEDOT:PSS on electron phonon coupling and conductivity

    NASA Astrophysics Data System (ADS)

    Lin, Yow-Jon; Ni, Wei-Shih; Lee, Jhe-You

    2015-06-01

    The effect of incorporation of ethylene glycol (EG) into poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on electron phonon coupling and conductivity is investigated. It is shown that the carrier density (NC) increases significantly and the carrier mobility (?) increases slightly at 300 K. The increased intensity of the Raman spectrum between 1400 and 1450 cm-1, following EG treatment (that is, the quinoid-dominated structures of the PEDOT chain), leads to an increase in the number of polarons (bipolarons), which leads to an increase in NC. In addition, ? in PEDOT:PSS samples with or without EG addition exhibits a strong temperature dependence, which demonstrates the dominance of tunneling (hopping) at low (high) temperatures. The high conductivity of PEDOT:PSS samples with the addition of EG is attributed to the combined effect of the modification of the electron-phonon coupling and the increase in NC (?).

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

    SciTech Connect

    Sera White

    2012-04-01

    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.

  15. Probabilistic seismic hazard estimates incorporating site effects - An example from Indiana, U.S.A

    USGS Publications Warehouse

    Hasse, J.S.; Park, C.H.; Nowack, R.L.; Hill, J.R.

    2010-01-01

    The U.S. Geological Survey (USGS) has published probabilistic earthquake hazard maps for the United States based on current knowledge of past earthquake activity and geological constraints on earthquake potential. These maps for the central and eastern United States assume standard site conditions with Swave velocities of 760 m/s in the top 30 m. For urban and infrastructure planning and long-term budgeting, the public is interested in similar probabilistic seismic hazard maps that take into account near-surface geological materials. We have implemented a probabilistic method for incorporating site effects into the USGS seismic hazard analysis that takes into account the first-order effects of the surface geologic conditions. The thicknesses of sediments, which play a large role in amplification, were derived from a P-wave refraction database with over 13, 000 profiles, and a preliminary geology-based velocity model was constructed from available information on S-wave velocities. An interesting feature of the preliminary hazard maps incorporating site effects is the approximate factor of two increases in the 1-Hz spectral acceleration with 2 percent probability of exceedance in 50 years for parts of the greater Indianapolis metropolitan region and surrounding parts of central Indiana. This effect is primarily due to the relatively thick sequence of sediments infilling ancient bedrock topography that has been deposited since the Pleistocene Epoch. As expected, the Late Pleistocene and Holocene depositional systems of the Wabash and Ohio Rivers produce additional amplification in the southwestern part of Indiana. Ground motions decrease, as would be expected, toward the bedrock units in south-central Indiana, where motions are significantly lower than the values on the USGS maps.

  16. Reionization on large scales. IV. Predictions for the 21 cm signal incorporating the light cone effect

    SciTech Connect

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

    2014-07-01

    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 {sup –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.

  17. Capillary electrokinetic separations: Influence of mobile phase composition on performance

    SciTech Connect

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

    1990-01-01

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

  18. EFFICIENT BIOMOLECULE PRE-CONCENTRATION BY NANOFILTER-TRIGGERED ELECTROKINETIC

    E-print Network

    nanofluidic device that can pre-concentrate dilute protein and peptide solution by electrokinetic trapping filter, one can generate an induced space charge layer as an energy barrier for charged biomolecules In this work, we use devices made of silicon nitride (by sacrificial layer etching) / PDMS or Si / SiO2 / glass

  19. 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...

  20. Nanocomposite scaffold fabrication by incorporating gold nanoparticles into biodegradable polymer matrix: Synthesis, characterization, and photothermal effect.

    PubMed

    Abdelrasoul, Gaser N; Farkas, Balazs; Romano, Ilaria; Diaspro, Alberto; Beke, Szabolcs

    2015-11-01

    Nanoparticle incorporation into scaffold materials is a valuable route to deliver various therapeutic agents, such as drug molecules or large biomolecules, proteins (e.g. DNA or RNA) into their targets. In particular, gold nanoparticles (Au NPs) with their low inherent toxicity, tunable stability and high surface area provide unique attributes facilitating new delivery strategies. A biodegradable, photocurable polymer resin, polypropylene fumarate (PPF) along with Au NPs were utilized to synthesize a hybrid nanocomposite resin, directly exploitable in stereolithography (SL) processes. To increase the particles' colloidal stability, the Au NP nanofillers were coated with polyvinyl pyrrolidone (PVP). The resulting resin was used to fabricate a new type of composite scaffold via mask projection excimer laser stereolithography. The thermal properties of the nanocomposite scaffolds were found to be sensitive to the concentration of NPs. The mechanical properties were augmented by the NPs up to 0.16?M, though further increase in the concentration led to a gradual decrease. Au NP incorporation rendered the biopolymer scaffolds photosensitive, i.e. the presence of Au NPs enhanced the optical absorption of the scaffolds as well, leading to possible localized temperature rise when irradiated with 532nm laser, known as the photothermal effect. PMID:26249594

  1. Effective removal of humic acid using xanthan gum incorporated polyethersulfone membranes.

    PubMed

    Sathish Kumar, R; Arthanareeswaran, G; Paul, Diby; Kweon, Ji Hyang

    2015-11-01

    In this study, xanthan gum (XA) was used as a hydrophilic biopolymer additive for the modification of polyethersulfone (PES) membrane to removal of humic acid (HA). The membranes are prepared using phase inversion technique and the concentration of XA was varied from 0.5 to 1.5wt%. The prepared membranes are characterized as a function of hydrophilicity, equilibrium water content (EWC), porosity studies and functional group analysis. Membrane surface and cross-sectional morphology was studied using scanning electron microscope. The lower contact angle value 64.2° was exhibited, when 1.5wt% of XA incorporated in PES membrane and this ensures that increase of hydrophilicity in pristine PES membrane. Further, higher water permeability (PWP) of 68.9(-9)m/skPa was observed for 1.5wt% of XA/PES membrane. The effect of pH on HA removal was studied for neat PES and XA/PES membranes. The rejection performance of XA incorporated in PES membranes were compared with commercial available PES membrane. PMID:25857244

  2. Incorporation of memory effects in coarse-grained modeling via the Mori-Zwanzig formalism.

    PubMed

    Li, Zhen; Bian, Xin; Li, Xiantao; Karniadakis, George Em

    2015-12-28

    The Mori-Zwanzig formalism for coarse-graining a complex dynamical system typically introduces memory effects. The Markovian assumption of delta-correlated fluctuating forces is often employed to simplify the formulation of coarse-grained (CG) models and numerical implementations. However, when the time scales of a system are not clearly separated, the memory effects become strong and the Markovian assumption becomes inaccurate. To this end, we incorporate memory effects into CG modeling by preserving non-Markovian interactions between CG variables, and the memory kernel is evaluated directly from microscopic dynamics. For a specific example, molecular dynamics (MD) simulations of star polymer melts are performed while the corresponding CG system is defined by grouping many bonded atoms into single clusters. Then, the effective interactions between CG clusters as well as the memory kernel are obtained from the MD simulations. The constructed CG force field with a memory kernel leads to a non-Markovian dissipative particle dynamics (NM-DPD). Quantitative comparisons between the CG models with Markovian and non-Markovian approximations indicate that including the memory effects using NM-DPD yields similar results as the Markovian-based DPD if the system has clear time scale separation. However, for systems with small separation of time scales, NM-DPD can reproduce correct short-time properties that are related to how the system responds to high-frequency disturbances, which cannot be captured by the Markovian-based DPD model. PMID:26723613

  3. Incorporation of memory effects in coarse-grained modeling via the Mori-Zwanzig formalism

    NASA Astrophysics Data System (ADS)

    Li, Zhen; Bian, Xin; Li, Xiantao; Karniadakis, George Em

    2015-12-01

    The Mori-Zwanzig formalism for coarse-graining a complex dynamical system typically introduces memory effects. The Markovian assumption of delta-correlated fluctuating forces is often employed to simplify the formulation of coarse-grained (CG) models and numerical implementations. However, when the time scales of a system are not clearly separated, the memory effects become strong and the Markovian assumption becomes inaccurate. To this end, we incorporate memory effects into CG modeling by preserving non-Markovian interactions between CG variables, and the memory kernel is evaluated directly from microscopic dynamics. For a specific example, molecular dynamics (MD) simulations of star polymer melts are performed while the corresponding CG system is defined by grouping many bonded atoms into single clusters. Then, the effective interactions between CG clusters as well as the memory kernel are obtained from the MD simulations. The constructed CG force field with a memory kernel leads to a non-Markovian dissipative particle dynamics (NM-DPD). Quantitative comparisons between the CG models with Markovian and non-Markovian approximations indicate that including the memory effects using NM-DPD yields similar results as the Markovian-based DPD if the system has clear time scale separation. However, for systems with small separation of time scales, NM-DPD can reproduce correct short-time properties that are related to how the system responds to high-frequency disturbances, which cannot be captured by the Markovian-based DPD model.

  4. Rapid estimation of octanol-water partition coefficients of pesticides by micellar electrokinetic chromatography.

    PubMed

    Wu, Y S; Lee, H K; Li, S F

    1998-07-01

    Micellar electrokinetic chromatography (MEKC) was evaluated as a new technique for the rapid estimation of octanol-water partition coefficient (logKow). Retention measurements for more than 40 reference pesticides with varied structural characteristics and hydrophobicity were carried out in two MEKC systems, based on sodium dodecyl sulfate (SDS) and sodium cholate (SC), respectively. To enable an accurate determination of capacity factors in the SC-MEKC system, cypermethrin (a synthetic pyrethroid insecticide) was utilized instead of Sudan III as the SC micelle tracer, since a few highly hydrophobic pesticides were found to elute after Sudan III. The linear correlation between logarithmic capacity factor (logk') and logKow in the two systems was examined. It was found that, under the typical buffer condition (10 mM sodium phosphate with 60 mM surfactant, pH 7.0), the SDS-MEKC system provided a somewhat wider dynamic range for hydrophobicity (logKow from -1.0 to 4.5). However, the correlation of logk' with logKow was not very high when all the reference pesticides were included in one single calibration set. For the SC-MEKC system, the dynamic range for logKow was in the range of 1.0-5.5, and a good linear correlation existed between logk' and logKow, even when all reference pesticides were incorporated into a single calibration group. By comparing the regression line of the reference pesticides with that of a group of simple aromatic derivatives, it was discovered that molecular size and functionality posed a less significant effect on the measurement of logKow in the SC-MEKC system than in the SDS-MEKC system. Thus, SC-MEKC shall be the system of choice for the estimation of logKow. The typical error on logKow determination using the current MEKC technique was within 0.5 units, suggesting that MEKC can be a valuable complement to reversed phase high performance liquid chromatography (RP-HPLC) for the indirect determination of logKow. Besides maintaining all the advantages of the HPLC approach, the MEKC technique showed some unique benefits, such as better inter-column reproducibility, higher throughput, and less handling of toxic pesticides and solvents. PMID:9719551

  5. Effect of hafnium-incorporation on the microstructure and dielectric properties of cobalt ferrite ceramics

    NASA Astrophysics Data System (ADS)

    Wells, Stephen Josiah

    The effect of hafnium ion (Hf4+) incorporation in cobalt ferrite (CFO) was studied. Samples of Hf substituted CFO ceramic (CoFe 2-xHfxO4), were synthesized in the laboratory with hafnium concentrations ranging from x=0.000 to x=0.200. X-ray diffraction scans show that the Hafnium CFO crystalizes in the inverse spinel phase. Inclusion of hafnium causes lattice expansion, increasing the lattice parameter from 8.374 A for pure CoFe2O4 to 8.391 A for the highest concentration of hafnium tested (x=0.020). The dielectric properties of CFO are greatly enhanced by inclusion of hafnium. The enhancement is due to the distortion on the lattice from the larger Hf-ions substituting the smaller Fe-ions. Frequency variation of the dielectric properties is well modeled by the modified Debye function, which takes into account multiple ions contributing to relaxation.

  6. The effect of fluorophore incorporation on fluorescence enhancement in colloidal photonic crystals.

    PubMed

    Eftekhari, Ehsan; Cole, Ivan S; Li, Qin

    2016-01-21

    The significant effect of photonic crystals (PhCs) on fluorophore emission has recently received intense interest. However, so far little attention has been paid on the influence of the fluorophore incorporation method on the performance of PhCs, particularly in practical applications. In this study, rhodamine B is immobilised on polystyrene spheres using a diffusion-swelling method, which are self-assembled into three-dimensional colloidal photonic crystal films. This immobilization method has resulted in 230-fold fluorescence enhancement compared to control films, the greatest fluorescence enhancement of RhB immobilised on monolithic colloidal photonic crystals compared to other immobilization methods such as infiltration and electrostatic charge-facilitated dye attachment on the particle surface. We further demonstrate the stability of dye attachment and the relationship between fluorescence intensity enhancement and the pseudo bandgap position relative to a fluorophore fluorescence peak. PMID:26674603

  7. Electrokinetic-enhanced bioaugmentation for remediation of chlorinated solvents contaminated clay

    PubMed Central

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

    2012-01-01

    Successful bioremediation of contaminated soils is controlled by the ability to deliver bioremediation additives, such as bacteria and/or nutrients, to the contaminated zone. Because hydraulic advection is not practical for delivery in clays, electrokinetic (EK) injection is an alternative for efficient and uniform delivery of bioremediation additive into low-permeability soil and heterogeneous deposits. EK–enhanced bioaugmentation for remediation of clays contaminated with chlorinated solvents is evaluated. Dehalococcoides (Dhc) bacterial strain and lactate ions are uniformly injected in contaminated clay and complete dechlorination of chlorinated ethene is observed in laboratory experiments. The injected bacteria can survive, grow, and promote effective dechlorination under EK conditions and after EK application. The distribution of Dhc within the clay suggests that electrokinetic transport of Dhc is primarily driven by electroosmosis. In addition to biodegradation due to bioaugmentation of Dhc, an EK-driven transport of chlorinated ethenes is observed in the clay, which accelerates cleanup of chlorinated ethenes from the anode side. Compared with conventional advection-based delivery, EK injection is significantly more effective forestablis hingmicrobial reductive dechlorination capacity in low-permeability soils. PMID:22365139

  8. Enhanced electrokinetic extraction of heavy metals from soils assisted by ion exchange membranes.

    PubMed

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

    2005-02-14

    The potential of electrokinetic remediation technology has been successfully demonstrated for the remediation of heavy metal contaminated fine-grained soils through laboratory scale and field application studies. Various enhancement techniques have been proposed and used in order to further improve the remediation process. However, it has been reported that such enhancement schemes can create other obstacles, such as the introduction of non-target ions into the system and thereby decrease the efficiency of the remediation process. Electrokinetic soil remediation technology enhanced by an ion exchange membrane (IEM), IEM-enhanced EK processing, was experimentally evaluated for the purpose of overcoming these obstacles. In particular, this study focused on observations of a fouling problem and its settlement using an auxiliary solution cell (ASC). In addition, the efficacies of two different types of electrode configurations, rectangular and cylindrical, were investigated. The experimental results indicate that the effectiveness of the technology was increased by an enhancement scheme using an IEM. This may be explained by the prevention of metal precipitation in the region near the cathode originating from hydroxide ions generated by the electrolysis of water in the cathode. The experimental results also imply that placement of the ASC can nullify the fouling problem within the cation exchange membranes used in IEM-enhanced EK processing, and thus improve the overall effectiveness of the process. The experimental results indicate that the cylindrical electrode configuration can be implemented in practical situations to improve the treatability of cathode effluent containing a high level of contaminants after processing. PMID:15721533

  9. Preparation,-Characterization and Anti-Glioma Effects of Docetaxel-Incorporated Albumin-Lipid Nanoparticles.

    PubMed

    Gao, Huile; Cao, Shijie; Yang, Zhi; Zhang, Shuang; Zhang, Qizhi; Jiang, Xinguo

    2015-12-01

    Poor aqueous solubility is a serious problem for most chemotherapeutics. Docetaxel (DTX), an inhibitor of microtubule depolymerization, is frequently used to treat many malignancies. However, the surfactant used in its commercial preparation (Taxotere) has proven problematic in clinical use because it has been associated with several side effects. By utilizing the high DTX-loading property of albumin, a new formulation, DTX-incorporated albumin-lipid nanoparticles (DNPs), was prepared and evaluated. DTX was bound to albumin in vitro and dispersed by egg yolk lecithin. The DNP particle size was 110.1 nm, while the average DNP zeta potential was -2.95 mV. The median lethal dose of DNPs was 180.6 mg/kg, which was 75.3% higher than that of Taxotere. DNPs could effectively inhibit the proliferation of several cell lines and induce cell apoptosis. In vivo imaging suggested that DNPs localize to and accumulate at the glioma site, which is likely due to the enhanced permeation and retention effects of DNPs. These pharmacological experiments further confirmed that DNPs can inhibit tumor growth, prolong the median survival time of mice with gliomas and induce higher levels of apoptosis. In conclusion, this novel formulation of DTX (DNPs) displayed lower toxicity and a superior anti-glioma effect relative to standard DTX preparations. PMID:26510308

  10. A transient electrochemical model incorporating the Donnan effect for all-vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Lei, Y.; Zhang, B. W.; Bai, B. F.; Zhao, T. S.

    2015-12-01

    In a typical all-vanadium redox flow battery (VRFB), the ion exchange membrane is directly exposed in the bulk electrolyte. Consequently, the Donnan effect occurs at the membrane/electrolyte (M/E) interfaces, which is critical for modeling of ion transport through the membrane and the prediction of cell performance. However, unrealistic assumptions in previous VRFB models, such as electroneutrality and discontinuities of ionic potential and ion concentrations at the M/E interfaces, lead to simulated results inconsistent with the theoretical analysis of ion adsorption in the membrane. To address this issue, this work proposes a continuous-Donnan effect-model using the Poisson equation coupled with the Nernst-Planck equation to describe variable distributions at the M/E interfaces. A one-dimensional transient VRFB model incorporating the Donnan effect is developed. It is demonstrated that the present model enables (i) a more realistic simulation of continuous distributions of ion concentrations and ionic potential throughout the membrane and (ii) a more comprehensive estimation for the effect of the fixed charge concentration on species crossover across the membrane and cell performance.

  11. Electrokinetic particle-electrode interactions at high frequencies.

    PubMed

    Yariv, Ehud; Schnitzer, Ory

    2013-01-01

    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

  12. Electrokinetic remediation of six emerging organic contaminants from soil.

    PubMed

    Guedes, Paula; Mateus, Eduardo P; Couto, Nazaré; Rodríguez, Yadira; Ribeiro, Alexandra B

    2014-12-01

    Some organic contaminants can accumulate in organisms and cause irreversible damages in biological systems through direct or indirect toxic effects. In this study the feasibility of the electrokinetic (EK) process for the remediation of 17?-oestradiol (E2), 17?-ethinyloestradiol (EE2), bisphenol A (BPA), nonylphenol (NP), octylphenol (OP) and triclosan (TCS) in soils was studied in a stationary laboratory cell. The experiments were conducted using a silty loam soil (S2) at 0, 10 and 20mA and a sandy soil (S3) at 0 and 10 mA. A pH control in the anolyte reservoir (pH>13) at 10 mA was carried out using S2, too. Photo and electrodegradation experiments were also fulfilled. Results showed that EK is a viable method for the remediation of these contaminants, both through mobilization by electroosmotic flow (EOF) and electrodegradation. As EOF is very sensible to soil pH, the control in the anolyte increased EOF rate, consequently enhancing contaminants mobilization towards the cathode end. The extent of the mobilization towards the electrode end was mainly dependent on compounds solubility and octanol-water partition coefficient. In the last 24h of experiments, BPA presented the highest mobilization rate (ca. 4 ?g min(-1)) with NP not being detected in the catholyte. At the end of all experiments the percentage of contaminants that remained in the soil ranged between 17 and 50 for S2, and between 27 and 48 for S3, with no statistical differences between treatments. The mass balance performed showed that the amount of contaminant not detected in the cell is similar to the quantity that potentially may suffer photo and electrodegradation. PMID:24997283

  13. On-line preconcentration of sodium dodecyl sulfate-protein complexes using electrokinetic supercharging method with a prefilled water plug in capillary sieving electrophoresis.

    PubMed

    Liu, Jing; Kang, Mingchao; Liu, Zhen

    2011-09-01

    An electrokinetic supercharging (EKS) method with a prefilled water plug at the head column of capillary was developed for on-line preconcentration of sodium dodecyl sulfate (SDS)-protein complexes in capillary sieving electrophoresis (CSE). Conventional EKS is a combination of electrokinetic injection with transient isotachophoresis (tr-ITP). The capillary is first filled with background electrolyte, then an appropriate amount of a leading electrolyte is filled and electro-injection is carried out for certain duration. After that, terminating electrolyte is filled, and tr-ITP is subsequently initiated, followed by capillary electrophoresis (CE) separation. In this work, the performance of EKS was evaluated by integrating multiple sub-methods step by step, and a water plug containing polymer was introduced before electrokinetic injection in order to further improve the concentration effect. The positive effects of the sub-methods were verified, including molecular sieving effect of polymer, field enhanced sample injection (FESI) with and without a water plug, and transient isotachophoretic electrophoresis-based FESI. It was observed that analyte discrimination usually encountered in conventional electrokinetic injection was eliminated due to the similar charge to mass ratios of SDS-protein complexes. Based on these results, a hybrid on-line preconcentration method, EKS with injecting a water plug containing polymer before sample electrokinetic injection, was proposed and used to indiscriminately preconcentrate SDS-protein complexes, which provided a sensitivity enhancement factor of more than 1000. It was very suitable for the analysis of low-abundance proteins, providing the information of their molecular mass. PMID:22233073

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

    SciTech Connect

    Wilson, D.J.; Rodriguez-Maroto, J.M.; Gomez-Lahoz, C.

    1995-09-01

    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.

  15. Cost-effective bioregeneration of nitrate-laden ion exchange brine through deliberate bicarbonate incorporation.

    PubMed

    Li, Qi; Huang, Bin; Chen, Xin; Shi, Yi

    2015-05-15

    Bioregeneration of nitrate-laden ion exchange brine is desired to minimize its environmental impacts, but faces common challenges, i.e., enriching sufficient salt-tolerant denitrifying bacteria and stabilizing brine salinity and alkalinity for stable brine biotreatment and economically removing undesired organics derived in biotreatment. Incorporation of 0.25 M bicarbonate in 0.5 M chloride brine little affected resin regeneration but created a benign alkaline condition to favor bio-based brine regeneration. The first-quarter sulfate-mainly enriched spent brine (SB) was acidified with carbon source acetic acid for using CaCl2 at an efficiency >80% to remove sulfate. Residual Ca(2+) was limited below 2 mM by re-mixing the first-quarter and remained SB to favor denitrification. Under [Formula: see text] system buffered pH condition (8.3-8.8), nitrate was removed at 0.90 gN/L/d by hematite-enriched well-settled activated sludge (SVI 8.5 ml/g) and the biogenic alkalinity was retained as bicarbonate. The biogenic alkalinity met the need of alkalinity in removing residual Ca(2+) after sulfate removal and in CaCl2-induced CaCO3 flocculation to remove 63% of soluble organic carbon (SOC) in biotreated brine. Carbon-limited denitrification was also operated after activated sludge acclimation with sulfide to cut SOC formation during denitrification. Overall, this bicarbonate-incorporation approach, stabilizing the brine salinity and alkalinity for stable denitrification and economical removal of undesired SOC, suits long-term cost-effective brine bioregeneration. PMID:25746960

  16. Analysis of catechins in extracts of Cistus species by microemulsion electrokinetic chromatography.

    PubMed

    Pomponio, Romeo; Gotti, Roberto; Santagati, N Alfredo; Cavrini, Vanni

    2003-03-21

    A microemulsion electrokinetic chromatographic (MEEKC) method was developed for the separation of six catechins, specific marker phytochemicals of Cistus species. The MEEKC method involved the use of sodium dodecyl sulfate (SDS) as surfactant, heptane as organic solvent and butan-1-ol as co-solvent. In order to have a better stability of the studied catechins, the separation was performed under acidic conditions (pH 2.5 phosphate buffer). The effects of SDS concentration and of the amount of organic solvent and co-solvent on the analyte resolution were evaluated. The optimized conditions (heptane 1.36% (w/v), SDS 2.31% (w/v), butan-1-ol 9.72% (w/v) and 50 mM sodium phosphate buffer (pH 2.5) 86.61% (w/v)) allowed a useful and reproducible separation of the studied analytes to be achieved. These conditions provided a different separation profile compared to that obtained under conventional micellar electrokinetic chromatography (MECK) using SDS. The method was validated and applied to the determination of catechin and gallocatechin in lyophilized extracts of Cistus incanus and Cistus monspeliensis. PMID:12685600

  17. Major ion and electrical potential distribution in soil under electrokinetic remediation.

    PubMed

    Wada, S; Umegaki, Y

    2001-06-01

    To assess the effect of pore water chemistry on the contaminant removal rate, we monitored major ion concentrations in the pore water and the electrical potential distribution of a soil during electrokinetic remediation treatment. On application of the voltage, the soil near the anode became acidic due to the electrolytic generation of H+, and the acid region gradually spread toward the cathode. The major cation in the acid region was, however, not H+ but Al3+ that arose from the acid-induced dissolution of soil minerals, and it migrated very slowly toward the cathode. The measured pH and accompanying ion concentrations indicated that the anomalously slow migration of Al3+ was due to its precipitation-dissolution reaction at the acid front. The stagnancy of Al3+ increased the ionic concentration, flattened the electrical potential profile, and in turn, diminished electromigration in the acid region. This seems to be one of the causes of the relatively low removal rate of cationic and anionic contaminants in electrokinetic treatments. PMID:11414012

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

    SciTech Connect

    Sepaniak, M.J.

    1993-10-01

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

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

    PubMed Central

    2014-01-01

    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. PMID:25024819

  20. Electrokinetic injection in capillary electrophoresis and its application to the analysis of inorganic compounds.

    PubMed

    Krivácsy, Z; Gelencsér, A; Hlavay, J; Kiss, G; Sárvári, Z

    1999-02-26

    In capillary electrophoresis, electrokinetic injection is a highly controversial sampling technique. It is a simple mode of sample introduction which is suitable for on-line preconcentration of the analytes, but its precision and accuracy are more strongly affected by experimental conditions compared to hydrodynamic injection. In the first part of this paper the features of electrokinetic and hydrodynamic injections are compared, followed by a detailed discussion on the different biases of electrokinetic injection and on how to reduce them. Finally, applications of the electrokinetic injection are reviewed with special emphasis on the analysis of inorganic compounds. PMID:10189689

  1. Downhole Measurements of Electrokinetic Potential to Monitor Flow in Oilfields

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

    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.

  2. Geochemical reconnaissance of heavy metals in kaolin after electrokinetic remediation.

    PubMed

    Al-Hamdan, Ashraf Z; Reddy, Krishna R

    2006-01-01

    The development or implementation of electrokinetic soil remediation technique requires a good knowledge of how the contaminants are retained within the soil-water system. This paper investigates the speciation and extent of migration of the heavy metals, Cr(VI), Cr(III), Ni(II), and Cd(II), during electrokinetic soil remediation. A geochemical assessment of how the contaminants are held within the kaolin soil under induced electric potential is made by using the equilibrium model MINEQL+. The study is performed for three different contaminant cases: the Cr(VI) existing alone in the soil, the Cr(VI) combined with Ni(II) and Cd(II) in the soil, and the Cr(VI) combined with Ni(II) and Cd(II) in the soil in the presence of a reducing agent (sulfide). The adsorption of the studied metals by kaolin was implemented as an electrostatic behavior. FITEQL 4.0 model was used to determine the equilibrium constants of the electrostatic adsorption model of kaolin for the studied metals by optimizing the experimental titration and adsorption data of kaolin. This study showed that the initial speciation of the contaminants in the soil prior to the electrokinetic treatment depends on the type and amounts of contaminants present as well as on the presence of the co-contaminants or any reducing agent. Moreover, the extent of migration of the contaminants is strongly dependent on their initial speciation prior electrokinetic treatment. This study also showed that adsorption and precipitation are the significant hindering mechanisms for the removal of heavy metals from kaolin soil during electrokinetic treatment. The adsorption and precipitation forms of Cr(III), Ni(II), and Cd(II) increased near the cathode and decreased near the anode, whereas the adsorption form of Cr(VI) increased near the anode as well as in the middle region. However, the precipitation form of Cr(III), Ni(II), and Cd(II) as Cr2O3 or Cr(OH)3, Ni(OH)2, and Cd(OH)2, respectively, dominates over their adsorption form as they get closer to the cathode. Overall this study demonstrates that the electrolysis reactions control contaminant speciation and distribution in the soil during electrokinetic remediation because of the generated variations in pH and redox potential in the soil as a result of these reactions. PMID:16401568

  3. Local reduced-density-matrix-functional theory: Incorporating static correlation effects in Kohn-Sham equations

    NASA Astrophysics Data System (ADS)

    Lathiotakis, Nektarios N.; Helbig, Nicole; Rubio, Angel; Gidopoulos, Nikitas I.

    2014-09-01

    We propose a scheme to bring reduced-density-matrix-functional theory into the realm of density functional theory (DFT) that preserves the accurate density functional description at equilibrium, while incorporating accurately static and left-right correlation effects in molecules and keeping the good computational performance of DFT-based schemes. The key ingredient is to relax the requirement that the local potential is the functional derivative of the energy with respect to the density. Instead, we propose to restrict the search for the approximate natural orbitals within a domain where these orbitals are eigenfunctions of a single-particle Hamiltonian with a local effective potential. In this way, fractional natural occupation numbers are accommodated into Kohn-Sham equations allowing for the description of molecular dissociation without breaking spin symmetry. Additionally, our scheme provides a natural way to connect an energy eigenvalue spectrum to the approximate natural orbitals and this spectrum is found to represent accurately the ionization potentials of atoms and small molecules.

  4. Design of reactive crystallization systems incorporating kinetics and mass-transfer effects

    SciTech Connect

    Kelkar, V.V.; Ng, K.M.

    1999-01-01

    A coherent approach for the design of reactive crystallization systems is presented by incorporating reaction and crystallization kinetics, and mass transfer, into an existing equilibrium-based conceptual design method. A generic model for a well-mixed crystallizer is developed; it is applicable to reacting systems with any number of components. The reaction, mass-transfer and dissolution Damhoehler numbers, and the nucleation and growth numbers which result from the generic model, represent the relative rates of the individual steps, and their effect on the resulting crystal-size distribution and the crystallizer productivity is discussed. Estimates are provided for the typical values of the dimensionless numbers. To describe the solubility behavior of solid-liquid systems, a generalized equation for the isothermal solubility of a solute in the presence of an arbitrary number of other components is presented. The effects of the dimensionless numbers on the process paths are shown on the phase diagrams for systems involving up to four components. The utility of this integrated approach in the design of reactive crystallization systems is discussed using examples involving single and coprecipitation systems, and a salting out crystallization system.

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

    SciTech Connect

    Nieves, L.A.

    1993-09-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    The effectiveness of incroporating a real-time oculometer system into a Boeing 737 commercial flight training program was studied. The study combined a specialized oculometer system with sophisticated video equipment that would allow instructor pilots (IPs) to monitor pilot and copilot trainees' instrument scan behavior in real-time, and provide each trainee with video tapes of his/her instrument scanning behavior for each training session. The IPs' performance ratings and trainees' self-ratings were compared to the performance ratings by IPs and trainees in a control group. The results indicate no difference in IP ratings or trainees' self-ratings for the control and experimental groups. The results indicated that the major beneficial role of a real-time oculometer system for pilots and copilots having a significant amount of flight experience would be for problem solving or refinement of instrument scanning behavior rather than a general instructional scheme. It is suggested that this line of research be continued with the incorporation of objective data (e.g., state of the aircraft data), measures of cost effectiveness and with trainees having less flight experience.

  7. Incorporating Latest Technologies in a Cost-Effective Design of Rainfall Catchment and Filtration Systems for Coastal Rhode Island Communities

    E-print Network

    Rhode Island, University of

    and storage unit. In addition, because the water quality can decrease as the water is stored, filtrationIncorporating Latest Technologies in a Cost-Effective Design of Rainfall Catchment and Filtration Latest Technologies in a Cost-Effective Design of Rainfall Catchment and Filtration Systems for Coastal

  8. Effect of strain on indium incorporation in heteroepitaxial (indium, gallium) nitride nanomaterials

    NASA Astrophysics Data System (ADS)

    Ewoldt, David A.

    2011-12-01

    One of the challenges facing LED lighting today is the achievement of low-cost true white lighting. Ideally, multiple LEDs of different colors, blue, red and green, would be utilized in order to achieve white light. Currently, the quality of green LEDs is low when compared to the red and blue counterparts. Green emission from LEDs is difficult to achieve due to phase segregation that occurs during growth of the (In,Ga)N LED structure, which separates into compositions of high and low InN concentration and prevents the moderate composition required for green emission. On the nanoscale, strain effects in the (In,Ga)N material system give rise to shifts in optical properties. Relieving strain allows for the incorporation of additional indium nitride, which shifts the wavelength of light emitted by the structure. In order to control strain effects, growth templates were fabricated by several methods (PAA, FIB, EBL). A robust process for fabrication of pores down to 25 nm in diameter has been developed in order to investigate this effect. From this process, a template using e-beam lithography has been created and then growth of (In,Ga)N on this template in a metallorganic chemical vapor deposition system was performed. As (In,Ga)N grows from the GaN substrate, it is naturally strained due to the lattice mismatch. Lateral growth out of the templates relieves strain by allowing the rods to expand as they grow out of the prepared pores. The effect of the diameter of pores on the emission characteristics has been analyzed and a strong logarithmic trend was discovered correlating emission wavelength to pore diameter. In addition to allowing control over the wavelength of emission based on pore diameter, the process that has been developed and demonstrated will allow a distribution of pore sizes that could facilitate color mixing.

  9. Testing and evaluation of electrokinetic decontamination of concrete

    SciTech Connect

    DePaoli, D.W.; Harris, M.T.; Ally, M.R.

    1996-10-01

    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.

  10. Modeling Electrokinetic Flows by the Smoothed Profile Method

    PubMed Central

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

    2010-01-01

    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. PMID:20352076

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

    PubMed

    Lim, Hayoung A; Draper, Ellary

    2011-01-01

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

  12. Antibacterial effects and biocompatibility of titanium surfaces with graded silver incorporation in titania nanotubes.

    PubMed

    Mei, Shenglin; Wang, Huaiyu; Wang, Wei; Tong, Liping; Pan, Haobo; Ruan, Changshun; Ma, Qianli; Liu, Mengyuan; Yang, Huiling; Zhang, Liang; Cheng, Yicheng; Zhang, Yumei; Zhao, Lingzhou; Chu, Paul K

    2014-05-01

    Most commercial dental implants are made of titanium (Ti) because Ti possesses excellent properties such as osseointegration. However, many types of Ti products still suffer from insufficient antibacterial capability and bacterial infection after surgery remains one of the most common and intractable complications. In this study, a dual process encompassing anodization and silver plasma immersion ion implantation (Ag PIII) is utilized to produce titania nanotubes (TiO?-NTs) containing Ag at different sites and depths. The concentration and depth of the incorporated Ag can be tailored readily by changing the PIII parameters. The Ag-embedded TiO?-NTs which retain the nanotubular morphology are capable of sterilizing oral pathogens as opposed to pure Ti plates and pristine TiO?-NTs. Biological assays indicate that the in vitro and in vivo biocompatibility of the sample plasma-implanted at a lower voltage of 0.5 kV (NT-Ag-0.5) is significantly compromised due to the large amount of surface Ag. On the other hand, the sample implanted at 1 kV (NT-Ag-1.0) exhibits unimpaired effects due to the smaller surface Ag accumulation. Sample NT-Ag-1.0 is further demonstrated to possess sustained antibacterial properties due to the large embedded depth of Ag and the technique and resulting materials have large potential in dental implants. PMID:24565524

  13. Effect of incorporating sugar beet pulp in the finisher diet on performance of geese.

    PubMed

    Arroyo, J; Brachet, M; Dubois, J P; Lavigne, F; Molette, C; Bannelier, C; Fortun-Lamothe, L

    2015-04-01

    The aim of this work was to study the effects of incorporating sugar beet pulp (SBP) into the diet on the development of the crop and performance of geese. A total of 480 1-day-old ganders were divided into three groups differing in the composition and mode of distribution of the diet offered from day 56 to 89. The following two diets were used: a standard diet (nitrogen-corrected apparent metabolizable energy, AMEn 11.44 MJ/kg; 160 g/kg CP) or a diet containing 10% of SBP (SBP diet; AMEn 11.47 MJ/kg; 160 g/kg CP). The swelling capacity (SC) hydration was higher for SBP than for the standard diet (3.62 v. 2.72 ml of H2O/g of dry matter at 60 min; P<0.05). In the Control group, birds were fed with a controlled time of access to a standard diet. Other birds were fed the SBP diet with a controlled time of access (SBPt group) or a controlled quantity offered (SBPq). From day 90 to 104, 88 birds/group were overfed with a mixture containing mainly corn. Body traits including volume of the crop were measured at day 89. Fatty liver weight and commercial grading were measured at d 104. Feed intake from day 56 to 89 was higher in the Control group than in the SBPt group (8097 v. 7545 g; P<0.05), feed intake in the SBPq group being intermediate (7801 g); however, live weights (LW) of the birds were similar in the three groups measured at day 89 (5746 g; P>0.05). At day 89, the volume of the crop tended to be higher in the SBPt compared with the Control group (52.8 v. 48.8 ml/kg of LW; P=0.101). After overfeeding, feed intake (12 922 g), weight gain (2412 g), LW (8170 g), fatty liver weight (875 g) and commercial grading of the fatty liver were similar (P>0.1) for all the three groups. Therefore, SBP could help adapt the digestive tract of waterfowl to high feed intake through an increase in the crop volume, but its method of use - that is, level of incorporation and mode of distribution - should continue to be investigated. PMID:25434525

  14. Principles of Micellar Electrokinetic Capillary Chromatography Applied in Pharmaceutical Analysis

    PubMed Central

    Hancu, Gabriel; Simon, Brigitta; Rusu, Aura; Mircia, Eleonora; Gyéresi, Árpád

    2013-01-01

    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. PMID:24312804

  15. Diagnosis of transient electrokinetic flow in microfluidic channels

    NASA Astrophysics Data System (ADS)

    Yan, Deguang; Yang, Chun; Nguyen, Nam-Trung; Huang, Xiaoyang

    2007-01-01

    Measuring the electro-osmotic velocity distributions in microchannels is usually performed for steady-state electrokinetic flows. Characterizing time-dependent electrokinetic flows is of importance to the development of microfluidic devices such as rapid capillary electrophoretic separation system, ac pumps, novel micromixers, etc. In this paper, we use a micron-resolution particle image velocimetry (micro-PIV) based phase locking technique with an ordinary PIV charge coupled device (CCD) camera to carry out an experimental study of the transient electrokinetic flow in microchannels by synchronizing different trigger signals for the laser, CCD camera, and in-house designed high-voltage switch. With the transient micro-PIV technique, we further propose a method to decouple the particle electrophoretic velocity from the micro-PIV measured velocity and to determine the zeta potential of the channel wall. The time evolution of the full-field, electro-osmotic velocity distributions in both open- and closed-end rectangular microchannels is obtained. Using the slip velocity approach and the measured channel zeta potential, the theoretical predictions of the transient electro-osmotic flow in the open- and closed-end microchannels are obtained, and they are found to be in good agreement with the experimental results.

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

    SciTech Connect

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

    2002-01-01

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

  17. Comparison of microemulsion electrokinetic chromatography and micellar electrokinetic chromatography as methods for the analysis of ten benzophenones.

    PubMed

    Huang, Hsi-Ya; Chiu, Chen-Wen; Chen, Yen-Chen; Yeh, Jui-Ming

    2005-02-01

    Microemulsion electrokinetic chromatography (MEEKC) and micellar electrokinetic chromatograpy (MEKC) were compared for their abilities to separate and detect ten similar benzophenones, which are commonly used as UV filters in various plastic and cosmetic products. Sodium dodecyl sulfate (SDS) concentration and column temperature rarely affected separation resolution for MEEKC, but separation of benzophenones could be improved by changing the SDS concentration and column temperature for MEKC. Buffer pH and ethanol (organic modifier) were found to markedly influence the separation selectivity for both MEEKC and MEKC systems. In addition, a higher electric voltage improved the separation efficiency without a noticeable reduction in separation resolution for MEEKC, whereas it caused a poor separation resolution for the MEKC system. PMID:15714549

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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.

  19. A soft-lithographed chaotic electrokinetic micromixer for efficient chemical reactions in lab-on-chips

    E-print Network

    M. Campisi; D. Accoto; F. Damiani; P. Dario

    2007-05-08

    Mixing is one of the basic functions which automated lab-on-chips require for the effective management of liquid samples. In this paper we report on the working principle, design, fabrication and experimental characterization of a soft-lithographed micromixer for microfluidic applications. The device effectively mixes two liquids by means of chaotic advection obtained as an implementation of a Linked Twisted Map (LTM). In this sense it is chaotic. The liquids are electrokinetically displaced by generating rolls through AC electroosmosis on co-planar electrodes. The device performance has been tested on dyed DI-water for several voltages, frequencies and flow-rates, displaying good mixing properties in the range of $10 \\div 100$kHz, at low peak-to-peak voltages ($\\sim15 \\div 20$ volts). Low voltage supply, small dimensions and possibility of fabrication via standard lithographic techniques make the device highly integrable in lab-on-a-chip platforms.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  1. The Effect of an Instructional Unit Incorporating Live Animals on Knowledge of Nutrition for Different Age Levels.

    ERIC Educational Resources Information Center

    Roth, Anne I.; Wunderlich, Kenneth W.

    A nutrition education unit, Rat Pak, developed by Dairy Council, Inc., is an attempt to influence students to make wise food choices. It consists of eleven lessons in an instructional sequence which incorporates the use of white rats as a means of illustrating the effect of improper diet while teaching proper diet. The purpose of this…

  2. Effects of Wheat Straw Incorporation on the Availability of Soil Nutrients and Enzyme Activities in Semiarid Areas

    PubMed Central

    Wei, Ting; Zhang, Peng; Wang, Ke; Ding, Ruixia; Yang, Baoping; Nie, Junfeng; Jia, Zhikuan; Han, Qingfang

    2015-01-01

    Soil infertility is the main barrier to dryland agricultural production in China. To provide a basis for the establishment of a soil amelioration technical system for rainfed fields in the semiarid area of northwest China, we conducted a four—year (2007–2011) field experiment to determine the effects of wheat straw incorporation on the arid soil nutrient levels of cropland cultivated with winter wheat after different straw incorporation levels. Three wheat straw incorporation levels were tested (H: 9000 kg hm-2, M: 6000 kg hm-2, and L: 3000 kg hm-2) and no straw incorporation was used as the control (CK). The levels of soil nutrients, soil organic carbon (SOC), soil labile organic carbon (LOC), and enzyme activities were analyzed each year after the wheat harvest. After straw incorporation for four years, the results showed that variable straw amounts had different effects on the soil fertility indices, where treatment H had the greatest effect. Compared with CK, the average soil available N, available P, available K, SOC, and LOC levels were higher in the 0–40 cm soil layers after straw incorporation treatments, i.e., 9.1–30.5%, 9.8–69.5%, 10.3–27.3%, 0.7–23.4%, and 44.4–49.4% higher, respectively. On average, the urease, phosphatase, and invertase levels in the 0–40 cm soil layers were 24.4–31.3%, 9.9–36.4%, and 42.9–65.3% higher, respectively. Higher yields coupled with higher nutrient contents were achieved with H, M and L compared with CK, where these treatments increased the crop yields by 26.75%, 21.51%, and 7.15%, respectively. PMID:25880452

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

    SciTech Connect

    Bernal, Susan A.; Mejia de Gutierrez, Ruby; Provis, John L.; Rose, Volker

    2010-06-15

    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.

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

    PubMed

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

    2011-01-01

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

  5. Sensitivity studies for incorporating the direct effect of sulfate aerosols into climate models

    NASA Astrophysics Data System (ADS)

    Miller, Mary Rawlings Lamberton

    2000-09-01

    Aerosols have been identified as a major element of the climate system known to scatter and absorb solar and infrared radiation, but the development of procedures for representing them is still rudimentary. This study addresses the need to improve the treatment of sulfate aerosols in climate models by investigating how sensitive radiative particles are to varying specific sulfate aerosol properties. The degree to which sulfate particles absorb or scatter radiation, termed the direct effect, varies with the size distribution of particles, the aerosol mass density, the aerosol refractive indices, the relative humidity and the concentration of the aerosol. This study develops 504 case studies of altering sulfate aerosol chemistry, size distributions, refractive indices and densities at various ambient relative humidity conditions. Ammonium sulfate and sulfuric acid aerosols are studied with seven distinct size distributions at a given mode radius with three corresponding standard deviations implemented from field measurements. These test cases are evaluated for increasing relative humidity. As the relative humidity increases, the complex index of refraction and the mode radius for each distribution correspondingly change. Mie theory is employed to obtain the radiative properties for each case study. The case studies are then incorporated into a box model, the National Center of Atmospheric Research's (NCAR) column radiation model (CRM), and NCAR's community climate model version 3 (CCM3) to determine how sensitive the radiative properties and potential climatic effects are to altering sulfate properties. This study found the spatial variability of the sulfate aerosol leads to regional areas of intense aerosol forcing (W/m2). These areas are particularly sensitive to altering sulfate properties. Changes in the sulfate lognormal distribution standard deviation can lead to substantial regional differences in the annual aerosol forcing greater than 2 W/m 2. Changes in the aerosol chemical composition can lead to regional changes in the aerosol forcing greater than 0.5 W/m2. The relative humidity is shown to greatly influence the aerosol optical properties. Given the differences in aerosol forcing found due to varying sulfate properties, this study does not encourage the use of a single aerosol distribution to represent sulfate particles of all air masses.

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

    SciTech Connect

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

    1991-03-01

    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.

  7. Electrokinetic filtration and separation of particles by size in single-spiral microchannels.

    NASA Astrophysics Data System (ADS)

    Dubose, John; Tupper, Nathaniel; Stonaker, John; Patel, Saurin; Xuan, Xiangchun

    2013-11-01

    In this talk we demonstrate the utility of single-spiral microchannels for the continuous filtration and separation of particles by size. The negative dielectrophoretic force used in manipulating particle trajectories arises from the continual non-uniformity of the imposed electric field within the curved channel. When subjected to an externally imposed direct current power supply to electrokinetically drive the flow, 5, 10, and 15 micrometer polystyrene beads in 1 mM phosphate buffer solutions are independently focused. The various experimentally determined voltages needed for complete particle focusing differ depending upon the diameter of the separate particle species, which allows for the possibility of the continuous filtration and separation of binary particle mixtures at the outlet of the single-spiral microchannel. We also demonstrate an effective separation of a ternary particle mixture by size in a single-spiral microchannel with multiple outlet reservoirs.

  8. Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils

    DOEpatents

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

    1995-01-01

    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.

  9. Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils

    DOEpatents

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

    1995-07-25

    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.

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

    PubMed

    Huang, Hsi-Ya; Hsieh, Shih-Huan

    2007-09-14

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

  11. Numerical homogenization of electrokinetic equations in porous media using lattice-Boltzmann simulations

    NASA Astrophysics Data System (ADS)

    Obliger, Amaël; Duvail, Magali; Jardat, Marie; Coelho, Daniel; Békri, Samir; Rotenberg, Benjamin

    2013-07-01

    We report the calculation of all the transfer coefficients which couple the solvent and ionic fluxes through a charged pore under the effect of pressure, electrostatic potential, and concentration gradients. We use a combination of analytical calculations at the Poisson-Nernst-Planck and Navier-Stokes levels of description and mesoscopic lattice simulations based on kinetic theory. In the absence of added salt, i.e., when the only ions present in the fluid are the counterions compensating the charge of the surface, exact analytical expressions for the fluxes in cylindrical pores allow us to validate a new lattice-Boltzmann electrokinetics (LBE) scheme which accounts for the osmotic contribution to the transport of all species. The influence of simulation parameters on the numerical accuracy is thoroughly investigated. In the presence of an added salt, we assess the range of validity of approximate expressions of the fluxes computed from the linearized Poisson-Boltzmann equation by a systematic comparison with LBE simulations.

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

    SciTech Connect

    Yang, L.; Harrata, A.K.; Lee, C.S.

    1997-05-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  15. EFFECTS OF ROCK FRAGMENTS INCORPORATED IN THE SOIL MATRIX ON CONCENTRATED FLOW HYDRAULICS AND EROSION 1836

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rock fragments can act as a controlling factor for erosional rates and patterns in the landscape. Thus, the objective of this study is to better understand the role that rock fragments incorporated into the soil matrix have on concentrated flow hydraulics and erosion . Laboratory flume experiments...

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

    SciTech Connect

    Jang, Moon Hyung; Park, Seung Jong; Lim, Dong Hyeok; Park, Sung Jin; Cho, Mann-Ho; Cho, Seong Jin; Cho, Yoon Ho; Lee, Jong-Heun

    2010-03-01

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

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

    ERIC Educational Resources Information Center

    Baumgartner, Lisa M.

    2012-01-01

    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,…

  18. The Perceived Effect of Time on HIV/AIDS Identity Incorporation

    ERIC Educational Resources Information Center

    Baumgartner, Lisa M.

    2012-01-01

    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.…

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

    SciTech Connect

    Pal, N.; Bessman, S.P.

    1988-07-15

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

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

    SciTech Connect

    T.D. Sisk; N.M. Haddad

    2002-01-01

    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.

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

    PubMed Central

    2010-01-01

    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. PMID:20459713

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

    PubMed

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

    2011-04-01

    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

  3. Low-disturbance manure incorporation effects on ammonia and nitrate loss.

    PubMed

    Dell, Curtis J; Kleinman, Peter J A; Schmidt, John P; Beegle, Douglas B

    2012-01-01

    Low-disturbance manure application methods can provide the benefits of manure incorporation, including reducing ammonia (NH3) emissions, in production systems where tillage is not possible. However, incorporation can exacerbate nitrate (NO3?) leaching. We sought to assess the trade-offs in NH3 and NO3? losses caused by alternative manure application methods. Dairy slurry (2006-2007) and liquid swine manure (2008-2009) were applied to no-till corn by (i) shallow (<10 cm) disk injection, (ii) surface banding with soil aeration, (iii) broadcasting, and (iv) broadcasting with tillage incorporation. Ammonia emissions were monitored for 72 h after application using ventilated chambers and passive diffusion samplers, and NO3? leaching to 80 cm was monitored with buried column lysimeters. The greatest NH3 emissions occurred with broadcasting (35-63 kg NH3-N ha?), and the lowest emissions were from unamended soil (<1 kg NH-N ha?¹). Injection decreased NH-N emissions by 91 to 99% compared with broadcasting and resulted in lower emissions than tillage incorporation 1 h after broadcasting. Ammonia-nitrogen emissions from banding manure with aeration were inconsistent between years, averaging 0 to 71% that of broadcasting. Annual NO3? leaching losses were small (<25 kg NO3-N ha?¹) and similar between treatments, except for the first winter when NO3? leaching was fivefold greater with injection. Because NO3? leaching with injection was substantially lower over subsequent seasons, we hypothesize that the elevated losses during the first winter were through preferential flow paths inadvertently created during lysimeter installation. Overall, shallow disk injection yielded the lowest NH3 emissions without consistently increasing NO3? leaching, whereas manure banding with soil aeration conserved inconsistent amounts of N. PMID:22565274

  4. Electrokinetic instability near charge-selective hydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Shelistov, V. S.; Demekhin, E. A.; Ganchenko, G. S.

    2014-07-01

    The influence of the texture of a hydrophobic surface on the electro-osmotic slip of the second kind and the electrokinetic instability near charge selective surfaces (permselective membranes, electrodes, or systems of microchannels and nanochannels) is investigated theoretically using a simple model based on the Rubinstein-Zaltzman approach. A simple formula is derived to evaluate the decrease in the instability threshold due to hydrophobicity. The study is complemented by numerical investigations both of linear and nonlinear instabilities near a hydrophobic membrane surface. Theory predicts a significant enhancement of the ion flux to the surface and shows a good qualitative agreement with the available experimental data.

  5. ELECTROKINETIC DENSIFICATION OF COAL FINES IN WASTE PONDS

    SciTech Connect

    E. James Davis

    1999-12-18

    The objective of this research was to demonstrate that electrokinetics can be used to remove colloidal coal and mineral particles from coal-washing ponds and lakes without the addition of chemical additives such as salts and polymeric flocculants. The specific objectives were: Design and develop a scaleable electrophoresis apparatus to clarify suspensions of colloidal coal and clay particles; Demonstrate the separation process using polluted waste water from the coal-washing facilities at the coal-fired power plants in Centralia, WA; Develop a mathematical model of the process to predict the rate of clarification and the suspension electrical properties needed for scale up.

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

    SciTech Connect

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

    1987-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  8. Electro-kinetic remediation coupled with phytoremediation to remove lead, arsenic and cesium from contaminated paddy soil.

    PubMed

    Mao, Xinyu; Han, Fengxiang X; Shao, Xiaohou; Guo, Kai; McComb, Jacqueline; Arslan, Zikri; Zhang, Zhanyu

    2016-03-01

    The objectives of this study were to investigate distribution and solubility of Pb, Cs and As in soils under electrokinetic field and examine the processes of coupled electrokinetic phytoremediation of polluted soils. The elevated bioavailability and bioaccumulation of Pb, As and Cs in paddy soil under an electro-kinetic field (EKF) were studied. The results show that the EKF treatment is effective on lowering soil pH to around 1.5 near the anode which is beneficial for the dissolution of metal(loid)s, thus increasing their overall solubility. The acidification in the anode soil efficiently increased the water soluble (SOL) and exchangeable (EXC) Pb, As and Cs, implying enhanced solubility and elevated overall potential bioavailability in the anode region while lower solubility in the cathode areas. Bioaccumulations of Pb, As and Cs were largely determined by the nature of elements, loading levels and EKF treatment. The native Pb in soil usually is not bioavailable. However, EKF treatment tends to transfer Pb to the SOL and EXC fractions improving the phytoextraction efficiency. Similarly, EKF transferred more EXC As and Cs to the SOL fraction significantly increasing their bioaccumulation in plant roots and shoots. Pb and As were accumulated more in plant roots than in shoots while Cs was accumulated more in shoots due to its similarity of chemical properties to potassium. Indian mustard, spinach and cabbage are good accumulators for Cs. Translocation of Pb, As and Cs from plant roots to shoots were enhanced by EKF. However, this study indicated the overall low phytoextraction efficiency of these plants. PMID:26650421

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

    PubMed Central

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

    2011-01-01

    The physicochemical properties and dynamics of bacterial envelope, play a major role in bacterial activity. In this study, the morphological, nanomechanical and electrohydrodynamic properties of Escherichia coli K-12 mutant cells were thoroughly investigated as a function of bulk medium ionic strength using atomic force microscopy (AFM) and electrokinetics (electrophoresis). Bacteria were differing according to genetic alterations controlling the production of different surface appendages (short and rigid Ag43 adhesins, longer and more flexible type 1 fimbriae and F pilus). From the analysis of the spatially resolved force curves, it is shown that cells elasticity and turgor pressure are not only depending on bulk salt concentration but also on the presence/absence and nature of surface appendage. In 1 mM KNO3, cells without appendages or cells surrounded by Ag43 exhibit large Young moduli and turgor pressures (?700–900 kPa and ?100–300 kPa respectively). Under similar ionic strength condition, a dramatic ?50% to ?70% decrease of these nanomechanical parameters was evidenced for cells with appendages. Qualitatively, such dependence of nanomechanical behavior on surface organization remains when increasing medium salt content to 100 mM, even though, quantitatively, differences are marked to a much smaller extent. Additionally, for a given surface appendage, the magnitude of the nanomechanical parameters decreases significantly when increasing bulk salt concentration. This effect is ascribed to a bacterial exoosmotic water loss resulting in a combined contraction of bacterial cytoplasm together with an electrostatically-driven shrinkage of the surface appendages. The former process is demonstrated upon AFM analysis, while the latter, inaccessible upon AFM imaging, is inferred from electrophoretic data interpreted according to advanced soft particle electrokinetic theory. Altogether, AFM and electrokinetic results clearly demonstrate the intimate relationship between structure/flexibility and charge of bacterial envelope and propensity of bacterium and surface appendages to contract under hypertonic conditions. PMID:21655293

  10. Electrokinetic removal of uranium from contaminated, unsaturated soils

    SciTech Connect

    Booher, W.F.; Lindgren, E.R.; Brady, P.V.

    1997-01-01

    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.

  11. Electrokinetics Enhanced Delivery of Nano-scale Zero Valent Iron

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    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.

  12. Cytotoxic effect of a lipophilic alkylating agent after incorporation into low density lipoprotein or emulsions: studies in human leukemic cells.

    PubMed

    Masquelier, Michèle; Lundberg, Bo; Peterson, Curt; Vitols, Sigurd

    2006-02-01

    The use of low density lipoprotein (LDL) as drug carrier in acute myeloblastic leukemia chemotherapy is attractive due to high LDL uptake by leukemic cells. Lipid-based formulations, such as liposomes or microemulsions are promising alternatives. In the current study, we incorporated N-trifluoroacetyl-adriamycin-14-valerate (AD32), a lipophilic derivative of daunorubicin (DNR), and WB4291, a lipophilic alkylating agent, into LDL or lipid microemulsions and evaluated their cytotoxic activities towards leukemic cell lines using as references DNR and melphalan. The incorporation of AD32 into LDL or emulsion resulted in complexes with poor cytotoxicity. WB4291-LDL and WB4291-emulsion exerted, on the other hand, promising cytotoxic effects towards parental and resistant K562 and HL60 cell lines. PMID:16085310

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

    PubMed

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

    2013-05-01

    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

  14. Effect of nitrogen incorporation in ferromagnetic (Ga,Mn)As epilayers

    NASA Astrophysics Data System (ADS)

    Oshiyama, I.; Kondo, T.; Munekata, H.

    2005-11-01

    Physical properties of ferromagnetic p-type Ga1-xMnxAs1-yNy epitaxial films (x=0.045 and y=0-0.032) grown by molecular-beam epitaxy are described. It is found that the incorporation of nitrogen gradually suppresses the metallic behavior of p-(Ga,Mn)As, especially at low temperatures. The Curie temperature TC decreases accordingly with increasing y value. The reduction in TC is discussed in terms of the suppression of hole-mediated long-range spin-exchange interaction due to the enhancement of carrier localization. Perpendicular magnetic anisotropy appears at the region around y=0.02, reflecting the reduced lattice constant due to substitutionally incorporated nitrogen. No significant change was found in the magnetic circular dichroism spectra in the photon energy region around the band gap of (Ga,Mn)As. Our experimental results show that the theoretical prediction based on the double exchange interaction [V. A. Dinh et al., Jpn. J. Appl. Phys., Part 2 42, L888 (2003)] is hardly materialized in this system.

  15. Effect of the incorporation of antimicrobial/antioxidant proteins on the properties of potato starch films.

    PubMed

    Moreno, Olga; Atarés, Lorena; Chiralt, Amparo

    2015-11-20

    Glycerol plasticized potato starch films containing bioactive proteins (lactoferrin (LF) and/or lysozyme (LZ), at 0.1 and 0.2 ratio with respect to starch) were obtained by casting method and characterized as to their microstructural, thermal and physical (water content, mechanical, water and oxygen barrier, optical) properties. The bioactive properties, named antioxidant and antimicrobial, of the proteins and the films were also characterized. The incorporation of proteins affected the structural and physical properties of potato starch films, while modifying their thermal behavior and increasing the glass transition temperature. Both proteins showed a certain degree of compatibility with starch chains through the bond formations (increase in Tg), while a part is separated and migrates to the film surface. Their incorporation, especially that of lactoferrin, greatly increased the film's brittleness, regardless of the films water content, although they enhance the water vapor and oxygen barrier properties, whatever the age of the film. Protein also reduced the film's transparency and gloss, while lactoferrin induced color changes. The thermal degradation of blend films and isolated proteins occurred at temperatures of over 250°C, which means that blend starch films can be thermoprocessed, according to their thermoplastic properties and following the usual practices of the plastics industries. A synergistic antimicrobial action against Escherichia coli and coliforms was observed when both LZ and LF were simultaneously applied. Both of these exhibited antioxidant capacity. PMID:26344291

  16. Polyphenolic extracts of edible flowers incorporated onto atelocollagen matrices and their effect on cell viability.

    PubMed

    López-García, Jorge; Kuceková, Zdenka; Humpolí?ek, Petr; Ml?ek, Ji?i; Sáha, Petr

    2013-01-01

    The phenolic extract of chives flowers (Allium schoenoprasum, Liliaceae), introduced Sage (Salvia pratensis, Lamiaceae), European elderberry (Sambucus nigra, Caprifoliaceae) and common dandelion (Taraxacum officinale, Asteraceae) were characterised by High Performance Liquid Chromatography and incorporated in different concentrations onto atelocollagen thin films. In order to assess the biological impact of these phenolic compounds on cell viability, human immortalised non-tumorigenic keratinocyte cell line was seeded on the thin films and cell proliferation was determined by using an MTT assay. In addition, their antimicrobial activity was estimated by using an agar diffusion test. Data indicated the concomitance between cell viability and concentration of polyphenols. These findings suggest that these phenolic-endowed atelocollagen films might be suitable for tissue engineering applications, on account of the combined activity of polyphenols and collagen. PMID:24177700

  17. Prioritizing urban sustainability solutions: coordinated approaches must incorporate scale-dependent built environment induced effects

    NASA Astrophysics Data System (ADS)

    Georgescu, M.; Chow, W. T. L.; Wang, Z. H.; Brazel, A.; Trapido-Lurie, B.; Roth, M.; Benson-Lira, V.

    2015-06-01

    Because of a projected surge of several billion urban inhabitants by mid-century, a rising urgency exists to advance local and strategically deployed measures intended to ameliorate negative consequences on urban climate (e.g., heat stress, poor air quality, energy/water availability). Here we highlight the importance of incorporating scale-dependent built environment induced solutions within the broader umbrella of urban sustainability outcomes, thereby accounting for fundamental physical principles. Contemporary and future design of settlements demands cooperative participation between planners, architects, and relevant stakeholders, with the urban and global climate community, which recognizes the complexity of the physical systems involved and is ideally fit to quantitatively examine the viability of proposed solutions. Such participatory efforts can aid the development of locally sensible approaches by integrating across the socioeconomic and climatic continuum, therefore providing opportunities facilitating comprehensive solutions that maximize benefits and limit unintended consequences.

  18. Effect of incorporating prebiotics in coating materials for the microencapsulation of Saccharomyces boulardii.

    PubMed

    Zamora-Vega, Rafael; Montañez-Soto, José Luis; Martínez-Flores, Héctor Eduardo; Flores-Magallón, Rebeca; Muñoz-Ruiz, Carlos Víctor; Venegas-González, José; Ariza Ortega, Teresita De Jesús

    2012-12-01

    The objective of this study was to microencapsulate Saccharomyces boulardii using the emulsion technique. To microencapsulate the yeast, alginate sodium blended with inulin and mucilage from Opuntiaficus-indica was used as a coating material. The textural properties of the gels formed by the encapsulating materials and the in vitro viability of the yeast strain in the simulated conditions were studied. Textural profile analyses of the gels revealed differences (p < 0.05) in hardness because alginate produced stronger gels, whereas the incorporation of other hydrocolloids with alginate decreased gel strength and resulted in a more uniform, cohesive gel matrix. When alginate was blended with mucilage and inulin, encapsulated yeast presented higher counts and more viable cells, as compared to free yeast following 30 days of storage at 4 °C. Encapsulated and free yeast had 76.1% and 63.3%, respectively, of cell viability after 35 days of storage. PMID:22594787

  19. Space-time resolved electrokinetics in cylindrical and semi-cylindrical microchannels

    E-print Network

    Michele Campisi

    2007-05-03

    It is shown show how to employ Bessel-Fourier series in order to obtain a complete space-time resolved description of electrokinetic phenomena in cylindrical and semi-cylindrical microfluidic channels.

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

    E-print Network

    Bazant, Martin Z.

    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 ...

  1. Research Article Electrokinetic stringency control in self-assembled monolayer-based

    E-print Network

    Wong, Pak Kin

    efficiency reveals that in situ electrokinetic stringency control is capable of discriminating single pathogens are common causes of patient morbidity and a major global healthcare challenge.1 For instance

  2. 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...

  3. Physicochemical phenomena of electro-kinetic extraction of inorganic contaminants from kaolinite 

    E-print Network

    Scott, Travis Brooks

    1994-01-01

    Experiments investigating the use of electro-kinetics for removal of inorganic chemicals from kaolinite clay were performed. Kaolinite was homogeneously saturated with a NaCl solution and consolidated to the desired void ratio. Fluid reservoir...

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

    E-print Network

    Cheow, Lih Feng

    We describe an electrokinetic concentration-enhanced aptamer affinity probe electrophoresis assay to achieve highly sensitive and quantitative detection of protein targets in a microfluidic device. The key weaknesses of ...

  5. 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 ...

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

    SciTech Connect

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

    2011-12-31

    A series of LiFe{sub 1-x}V{sub x}PO{sub 4}/C samples have been successfully prepared using a two-step solid-state reaction route. The effect of vanadium incorporation on the performance of LiFePO{sub 4} has systematically been investigated with X-ray diffraction, Raman spectroscopy, charge/discharge measurements, and cyclic voltammetry tests. It is found that V incorporation significantly enhances the electrochemical performance of LiFePO{sub 4}. Particularly, the LiFePO{sub 4}/C sample with 5 at. % vanadium doping exhibits the best performance with a specific discharge capacity of 129 mAh g{sup -1} at 5.0 C after 50 cycles; the capacity retention ratio is higher than 97.5% at all C rates from 0.1 to 5.0 C. X-ray absorption spectroscopy results show that the valence of V in LiFe{sub 0.95}V{sub 0.05}PO{sub 4}/C is between +3 and +4. It is confirmed that the samples with x {le} 0.03 are in single phase, whereas the samples with 0.05 {le} x < 1.00 contain two impurity phases: Li{sub 3}V{sub 2}(PO{sub 4}){sub 3} and LiVOPO{sub 4}. A clear feature of vanadium incorporation in LiFePO{sub 4} has been specified.

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

    SciTech Connect

    Pullen, D.L.; Emergy, R.S. ); Palmquist, D.L. )

    1989-01-01

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

  8. Development of an integrated, in-situ remediation technology: Task 2--4, electrokinetic modeling. Topical report, September 26--May 25, 1996

    SciTech Connect

    1997-05-01

    This report summarizes the work conducted in Tasks 2-4, which together make up the Electrokinetic Modeling carried out in this project. The modeling was divided into three main sections: thermal analysis, chemical species transport, and electrode geometry and soil heterogeneity issues. The thermal modeling consisted of development of the governing equations to incorporate Joule heating associated with electro-osmosis, heat conduction and convection, and temperature dependencies of electrical conductivity and electro-osmotic permeability. To model the transport of chemical species in the Lasagna{sup TM} process, a one-dimensional model was developed. This model is based on previous models, but includes additional mechanism to account for charge transfer in the double layer, pH buffering of the soil, and zeta potential dependency on pH and ionic strength. The results of this model and the corroboration by experimental measurement support some key assumptions made in the thermal model. An analysis was also conducted to compare the use of cylindrical electrodes to the plate geometry used in Phase I. In summary, cylindrical electrodes may be appropriate for anodes, because the do not intercept the flow. If used as cathodes, a planar treatment zone in their vicinity would probably be required. The cylindrical electrodes can operate at reasonable current densities without boiling water. Because the hottest region is at the electrode, cooling schemes could be used to operate at higher current densities. If iron anodes are used, they will have to be quite massive, and may not be economical compared to planar models. An example of soil heterogeneity was investigated when it was discovered that a steel pt was buried in the vicinity of the pilot test. There is some distortion of the field near the pit, but its effects on the test zone between the electrodes are minimal.

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

    PubMed Central

    2012-01-01

    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. PMID:22958501

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

  11. Enhanced electrokinetic manipulation and impedance sensing using FPGA digital signal processing

    NASA Astrophysics Data System (ADS)

    Higginbotham, Steven N.; Sweatman, Denis R.

    2006-01-01

    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.

  12. Electrokinetic demonstration at Sandia National Laboratories: Use of transference numbers for site characterization and process evaluation

    SciTech Connect

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

    1997-03-01

    Electrokinetic remediation is generally an in situ method using direct current electric potentials to move ionic contaminants and/or water to collection electrodes. The method has been extensively studied for application in saturated clayey soils. Over the past few years, an electrokinetic extraction method specific for sandy, unsaturated soils has been developed and patented by Sandia National Laboratories. A RCRA RD&D permitted demonstration of this technology for the in situ removal of chromate contamination from unsaturated soils in a former chromic acid disposal pit was operated during the summer and fall of 1996. This large scale field test represents the first use of electrokinetics for the removal of heavy metal contamination from unsaturated soils in the United States and is part of the US EPA Superfund Innovative Technology Evaluation (SITE) Program. Guidelines for characterizing a site for electrokinetic remediation are lacking, especially for applications in unsaturated soil. The transference number of an ion is the fraction of the current carried by that ion in an electric field and represents the best measure of contaminant removal efficiency in most electrokinetic remediation processes. In this paper we compare the transference number of chromate initially present in the contaminated unsaturated soil, with the transference number in the electrokinetic process effluent to demonstrate the utility of evaluating this parameter.

  13. Electrokinetic In Situ Treatment of Metal-Contaminated Soil

    NASA Technical Reports Server (NTRS)

    Quinn, Jacqueline; Clausen, Christian A., III; Geiger, Cherie; Reinhart, Debra

    2004-01-01

    An electrokinetic technique has been developed as a means of in situ remediation of soils, sludges, and sediments that are contaminated with heavy metals. Examples of common metal contaminants that can be removed by this technique include cadmium, chromium, zinc, lead, mercury, and radionuclides. Some organic contaminants can also be removed by this technique. In the electrokinetic technique, a low-intensity direct current is applied between electrodes that have been implanted in the ground on each side of a contaminated soil mass. The electric current causes electro-osmosis and migration of ions, thereby moving aqueous-phase subsurface contaminants from one electrode to the other. The half reaction at the anode yields H+, thereby generating an acid front that travels from the anode toward the cathode. As this acid front passes through a given location, the local increase in acidity increases the solubility of cations that were previously adsorbed on soil particles. Ions are transported towards one electrode or the other which one depending on their respective electric charges. Upon arrival at the electrodes, the ionic contaminants can be allowed to become deposited on the electrodes or can be extracted to a recovery system. Surfactants and other reagents can be introduced at the electrodes to enhance rates of removal of contaminants. Placements of electrodes and concentrations and rates of pumping of reagents can be adjusted to maximize efficiency. The basic concept of electrokinetic treatment of soil is not new. What is new here are some of the details of application and the utilization of this technique as an alternative to other techniques (e.g., flushing or bioremediation) that are not suitable for treating soils of low hydraulic conductivity. Another novel aspect is the use of this technique as a less expensive alternative to excavation: The cost advantage over excavation is especially large in settings in which contaminated soil lies near and/or under industrial buildings and therefore excavation would be made even more expensive by the need to prevent damage to numerous underground pipes and cables.

  14. Proliferation kinetics of perturbed cell populations determined by the bromodeoxyuridine-33258 technique: radiotoxic effects of incorporated (3H)thymidine

    SciTech Connect

    Beck, H.P.

    1981-11-01

    A simple analytical method is described for the evaluation of flow cytometric data of perturbed cell populations obtained by applying the BrdUrd-33258 Hoechst technique. This procedure allows for determining the growth curve, the efflux from and the influx into G2 + M as well as the transit characteristics of cell cohorts through the G2 + M phase. As an example of the application of the method, the radiotoxic effects of incorporated 3H-thymidine on the proliferation of L-929 cells in vitro are described.

  15. Effect of different hydroxyapatite incorporation methods on the structural and biological properties of porous collagen scaffolds for bone repair.

    PubMed

    Ryan, Alan J; Gleeson, John P; Matsiko, Amos; Thompson, Emmet M; O'Brien, Fergal J

    2014-11-20

    Scaffolds which aim to provide an optimised environment to regenerate bone tissue require a balance between mechanical properties and architecture known to be conducive to enable tissue regeneration, such as a high porosity and a suitable pore size. Using freeze-dried collagen-based scaffolds as an analogue of native ECM, we sought to improve the mechanical properties by incorporating hydroxyapatite (HA) in different ways while maintaining a pore architecture sufficient to allow cell infiltration, vascularisation and effective bone regeneration. Specifically we sought to elucidate the effect of different hydroxyapatite incorporation methods on the mechanical, morphological, and cellular response of the resultant collagen-HA scaffolds. The results demonstrated that incorporating either micron-sized (CHA scaffolds) or nano-sized HA particles (CnHA scaffolds) prior to freeze-drying resulted in moderate increases in stiffness (2.2-fold and 6.2-fold, respectively, vs. collagen-glycosaminoglycan scaffolds, P < 0.05, a scaffold known to support osteogenesis), while enabling good cell attachment, and moderate mesenchymal stem cell (MSC)-mediated calcium production after 28 days' culture (2.1-fold, P < 0.05, and 1.3-fold, respectively, vs. CG scaffolds). However, coating of collagen scaffolds with a hydroxyapatite precipitate after freeze-drying (CpHA scaffolds) has been shown to be a highly effective method to increase the compressive modulus (26-fold vs. CG controls, P < 0.001) of scaffolds while maintaining a high porosity (~ 98%). The coating of the ligand-dense collagen structure results in a lower cell attachment level (P < 0.05), although it supported greater cell-mediated calcium production (P < 0.0001) compared with other scaffold variants after 28 days' culture. The comparatively good mechanical properties of these high porosity scaffolds is obtained partially through highly crosslinking the scaffolds with both a physical (DHT) and chemical (EDAC) crosslinking treatment. Control of scaffold microstructure was examined via alterations in freezing temperature. It was found that the addition of HA prior to freeze-drying generally reduced the pore size and so the CpHA scaffold fabrication method offered increased control over the resulting scaffolds microstructure. These findings will help guide future design considerations for composite biomaterials and demonstrate that the method of HA incorporation can have profound effects on the resulting scaffold structural and biological response. PMID:25409684

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

    SciTech Connect

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

    2013-11-04

    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.

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

    SciTech Connect

    Apte, Swapna; Sanders, David Avram

    2010-09-15

    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.

  18. Effects of straw incorporation along with microbial inoculant on methane and nitrous oxide emissions from rice fields.

    PubMed

    Liu, Gang; Yu, Haiyang; Ma, Jing; Xu, Hua; Wu, Qinyan; Yang, Jinghui; Zhuang, Yiqing

    2015-06-15

    Incorporation of straw together with microbial inoculant (a microorganism agent, accelerating straw decomposition) is being increasingly adopted in rice cultivation, thus its effect on greenhouse gas (GHG) emissions merits serious attention. A 3-year field experiment was conducted from 2010 to 2012 to investigate combined effect of straw and microbial inoculant on methane (CH4) and nitrous oxide (N2O) emissions, global warming potential (GWP) and greenhouse gas intensity (GHGI) in a rice field in Jurong, Jiangsu Province, China. The experiment was designed to have treatment NPK (N, P and K fertilizers only), treatment NPKS (NPK plus wheat straw), treatment NPKSR (NPKS plus Ruilaite microbial inoculant) and treatment NPKSJ (NPKS plus Jinkuizi microbial inoculant). Results show that compared to NPK, NPKS increased seasonal CH4 emission by 280-1370%, while decreasing N2O emission by 7-13%. When compared with NPKS, NPKSR and NPKSJ increased seasonal CH4 emission by 7-13% and 6-12%, respectively, whereas reduced N2O emission by 10-27% and 9-24%, respectively. The higher CH4 emission could be attributed to the higher soil CH4 production potential triggered by the combined application of straw and microbial inoculant, and the lower N2O emission to the decreased inorganic N content. As a whole, the benefit of lower N2O emission was completely offset by increased CH4 emission, resulting in a higher GWP for NPKSR (5-12%) and NPKSJ (5-11%) relative to NPKS. Due to NPKSR and NPKSJ increased rice grain yield by 3-6% and 2-4% compared to NPKS, the GHGI values for NPKS, NPKSR and NPKSJ were comparable. These findings suggest that incorporating straw together with microbial inoculant would not influence the radiative forcing of rice production in the terms of per unit of rice grain yield relative to the incorporation of straw alone. PMID:25756676

  19. Entropic Electrokinetics: Recirculation, Particle Separation, and Negative Mobility

    NASA Astrophysics Data System (ADS)

    Malgaretti, Paolo; Pagonabarraga, Ignacio; Rubi, J. Miguel

    2014-09-01

    We show that when particles are suspended in an electrolyte confined between corrugated charged surfaces, electrokinetic flows lead to a new set of phenomena such as particle separation, mixing for low-Reynolds micro- and nanometric devices, and negative mobility. Our analysis shows that such phenomena arise, for incompressible fluids, due to the interplay between the electrostatic double layer and the corrugated geometrical confinement and that they are magnified when the width of the channel is comparable to the Debye length. Our characterization allows us to understand the physical origin of such phenomena, therefore, shedding light on their possible relevance in a wide variety of situations ranging from nano- and microfluidic devices to biological systems.

  20. Entropic electrokinetics: recirculation, particle separation and negative mobility

    E-print Network

    Paolo Malgaretti; Ignacio Pagonabarraga; J. Miguel Rubi

    2014-09-23

    We show that when particles are suspended in an electrolyte confined between corrugated charged surfaces, electrokinetic flows lead to a new set of phenomena such as particle separation, mixing for low-Reynolds micro- and nano-metric devices and negative mobility. Our analysis shows that such phenomena arise, for incompressible fluids, due to the interplay between the electrostatic double layer and the corrugated geometrical confinement and that they are magnified when the width of the channel is comparable to the Debye length. Our characterization allows us to understand the physical origin of such phenomena therefore shading light on their possible relevance in a wide variety of situations, ranging from nano- and micro-fluidic devices to biological systems.

  1. Entropic electrokinetics: recirculation, particle separation and negative mobility

    E-print Network

    Malgaretti, Paolo; Rubi, J Miguel

    2014-01-01

    We show that when particles are suspended in an electrolyte confined between corrugated charged surfaces, electrokinetic flows lead to a new set of phenomena such as particle separation, mixing for low-Reynolds micro- and nano-metric devices and negative mobility. Our analysis shows that such phenomena arise, for incompressible fluids, due to the interplay between the electrostatic double layer and the corrugated geometrical confinement and that they are magnified when the width of the channel is comparable to the Debye length. Our characterization allows us to understand the physical origin of such phenomena therefore shading light on their possible relevance in a wide variety of situations, ranging from nano- and micro-fluidic devices to biological systems.

  2. Mechanistic studies of partial-filing micellar electrokinetic chromatography

    SciTech Connect

    Nelson, W.M.; Lee, C.S.

    1996-09-15

    The need for coupling micellar electrokinetic chromatography (MEKC) with electrospray mass spectrometry initiates the development of partial-filling MEKC. In comparison with conventional MEKC, only a small portion of the capillary is filled with a micellar solution for performing the separation in partial-filling MEKC. Analytes first migrate into the micellar plug, where the separation occurs, and then into the leading electrophoresis buffer, which is free of surfactants. A theoretical model is proposed for predicting the separation behavior of triazine herbicides in partial-filling MEKC. The comparisons between conventional and partial-filling MEKC in terms of separation efficiency and resolution of triazine herbicides are presented and discussed. The optimization techniques, possible applications, and advantages of partial-filling MEKC are similarly addressed. 11 refs., 6 figs., 5 tabs.

  3. Electrokinetic characteristics of HSA dimer and its monolayers at mica.

    PubMed

    Kujda, Marta; Adamczyk, Zbigniew; Zapotoczny, Szczepan; Kowalska, Ewa

    2015-12-01

    Human serum albumin (HSA) dimer was synthesized in a reaction of the monomer with 1,6-bis(maleimido)hexane (BMH) cross-linker. Thorough physicochemical characteristics of the dimer were performed. They comprised the diffusion coefficient, hydrodynamic diameter, electrophoretic mobility as a function of pH, isoelectric point and electrokinetic charge. The adsorption of the dimer molecules at mica was studied using the atomic force microscopy (AFM) and in situ streaming potential measurements. The kinetics of adsorption was determined by a direct AFM imaging of single molecules over various substrate areas and interpreted in terms of the random sequential adsorption model. These results were consistent with streaming potential measurements carried out for the parallel-plate channel flow. It was also shown by these measurements that the desorption of the monomer under flow conditions was negligible. In this way, the amount of irreversibly bound dimer was quantitatively evaluated to be 0.5mgm(-2) for ionic strength of 0.01 and pH 3.5 that is similar that to previous result obtained for the albumin monomer. This indicates that the dimer adsorption occurs mostly in the side-on orientation. Finally, the electrokinetic characteristics of the dimer monolayers on mica were performed by the streaming potential method. It was observed that for lower pHs the zeta potential of monolayers is much lower than the bulk zeta potential of the dimer molecules. This was attributed to a heterogeneous charge distribution. It was concluded that the well-characterized HSA dimer monolayers can be used for quantitatively determining ligand and drug binding that has an essential practical significance. PMID:26613862

  4. 46 CFR 162.017-1 - Preemptive effect; incorporation by reference.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...ENGINEERING EQUIPMENT General Provisions; Valves, Pressure-Vacuum Relief, for Tank Vessels § 162.017-1 Preemptive effect... (1) ISO 15364, Ships and Marine Technology—Pressure/Vacuum Valves for Cargo Tanks, First Edition (Sep. 1,...

  5. 46 CFR 162.017-1 - Preemptive effect; incorporation by reference.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...ENGINEERING EQUIPMENT General Provisions; Valves, Pressure-Vacuum Relief, for Tank Vessels § 162.017-1 Preemptive effect... (1) ISO 15364, Ships and Marine Technology—Pressure/Vacuum Valves for Cargo Tanks, First Edition (Sep. 1,...

  6. A METHOD TO INCORPORATE ECOLOGY INTO RESIDENCE TIME OF CHEMICALS IN EMBAYMENTS: LOCAL EFFECT TIME

    EPA Science Inventory

    Residence times are classically defined by the physical and chemical aspects of water bodies rather than by their ecological implications. Therefore, a more clear and direct connection between the residence times and ecological effects is necessary to quantitatively relate these ...

  7. Incorporation of analgesics into rodent embryo transfer protocols: assessing the effects on reproductive outcomes 

    E-print Network

    Burckhardt, Heather Ann

    2009-05-15

    Surgical embryo transfer in rodents is a common procedure in today’s research laboratory, although little is known of the effect analgesics may have on not only the recipient female but also the embryos. Two perioperative analgesics, ketoprofen...

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

    PubMed

    Bandopadhyay, Aditya; Chakraborty, Suman

    2012-05-01

    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

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

    ERIC Educational Resources Information Center

    Hilbelink, Amy J.

    2009-01-01

    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…

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

    ERIC Educational Resources Information Center

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

    2008-01-01

    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…

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

    EPA Science Inventory

    In order to avoid a bias toward highly toxic but poorly bioavailable compounds in the effect-directed analysis (EDA) of soils and sediments, approaches are discussed to consider bioavailability in EDA procedures. In parallel, complimentary approaches for making toxicity identific...

  12. Development of a set of equations for incorporating disk flexibility effects in rotordynamical analyses

    NASA Technical Reports Server (NTRS)

    Flowers, George T.; Ryan, Stephen G.

    1991-01-01

    Rotordynamical equations that account for disk flexibility are developed. These equations employ free-free rotor modes to model the rotor system. Only transverse vibrations of the disks are considered, with the shaft/disk system considered to be torsionally rigid. Second order elastic foreshortening effects that couple with the rotor speed to produce first order terms in the equations of motion are included. The approach developed in this study is readily adaptable for usage in many of the codes that are current used in rotordynamical simulations. The equations are similar to those used in standard rigid disk analyses but with additional terms that include the effects of disk flexibility. An example case is presented to demonstrate the use of the equations and to show the influence of disk flexibility on the rotordynamical behavior of a sample system.

  13. Effect of sodium incorporation into CuInSe2 from first principles

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

  14. The dilemma of hyperbolic heat conduction and its settlement by incorporating spatially nonlocal effect at nanoscale

    NASA Astrophysics Data System (ADS)

    Yu, Y. Jun; Li, Chen-Lin; Xue, Zhang-Na; Tian, Xiao-Geng

    2016-01-01

    To model transiently thermal responses of numerous thermal shock issues at nano-scale, Fourier heat conduction law is commonly extended by introducing time rate of heat flux, and comes to hyperbolic heat conduction (HHC). However, solution to HHC under Dirichlet boundary condition depicts abnormal phenomena, e.g. heat conducts from the cold to the hot, and there are two temperatures at one location. In this paper, HHC model is further perfected with the aids of spatially nonlocal effect, and the exceeding temperature as well as the discontinuity at the wave front are avoided. The effect of nonlocal parameter on temperature response is discussed. From the analysis, the importance of size effect for nano-scale heat conduction is emphasized, indicating that spatial and temporal extensions should be simultaneously made to nano-scale heat conduction. Beyond that, it is found that heat flux boundary conditions should be directly given, instead of Neumann boundary condition, which does not make sense any longer for non-classical heat conductive models. And finally, it is observed that accurate solution to such problems may be obtained using Laplace transform method, especially for the time-dependent boundary conditions, e.g. heat flux boundary condition.

  15. Incorporating anthropogenic effects into trophic ecology: predator-prey interactions in a human-dominated landscape.

    PubMed

    Dorresteijn, Ine; Schultner, Jannik; Nimmo, Dale G; Fischer, Joern; Hanspach, Jan; Kuemmerle, Tobias; Kehoe, Laura; Ritchie, Euan G

    2015-09-01

    Apex predators perform important functions that regulate ecosystems worldwide. However, little is known about how ecosystem regulation by predators is influenced by human activities. In particular, how important are top-down effects of predators relative to direct and indirect human-mediated bottom-up and top-down processes? Combining data on species' occurrence from camera traps and hunting records, we aimed to quantify the relative effects of top-down and bottom-up processes in shaping predator and prey distributions in a human-dominated landscape in Transylvania, Romania. By global standards this system is diverse, including apex predators (brown bear and wolf), mesopredators (red fox) and large herbivores (roe and red deer). Humans and free-ranging dogs represent additional predators in the system. Using structural equation modelling, we found that apex predators suppress lower trophic levels, especially herbivores. However, direct and indirect top-down effects of humans affected the ecosystem more strongly, influencing species at all trophic levels. Our study highlights the need to explicitly embed humans and their influences within trophic cascade theory. This will greatly expand our understanding of species interactions in human-modified landscapes, which compose the majority of the Earth's terrestrial surface. PMID:26336169

  16. Effects of radiation and fission product incorporation in a yttria-stabilized zirconia based inert matrix fuel

    NASA Astrophysics Data System (ADS)

    Zhu, Sha

    This work has investigated the irradiation and incorporation effects of fission products in a yttria-stabilized zirconia (YSZ) based inert matrix fuel (IMF). The concept of inert matrix fuel is based on a new strategy for disposition of plutonium generated from the reprocessing of commercial nuclear fuel and the dismantling of nuclear weapons, i.e. using uranium-free oxides to "burn" plutonium and other actinides (Np, Cm, and Am) in reactors. This approach allows direct disposal, without reprocessing, after once-through burn-up. YSZ and MgAl2O4-YSZ composites are among the potential ceramics for IMF due to their high chemical durability and radiation resistance. The research involved investigating the production, nature, and accumulation of irradiation-induced defects, the behavior of the fission products in the ceramics, the structural stability and amorphization resistance of the YSZ during implantation. Ion implantations were conducted with 200--400 keV Cs+, Sr+, I+, Xe+ and Ti+ up to fluences of 1 x 1017/cm 2 at both room temperature and temperatures of 600--700°C. Thermal annealing was subsequently completed after room temperature ion implantations. In situ and ex situ transmission electron microscopy (TEM), optical absorption spectroscopy, photo-luminescence spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy were employed to characterize the irradiation induced defect evolution and analyze the defect structures. Various irradiation effects were observed and determined in the experiments, such as point defects (F type and V type color centers), defect clusters (dislocation loops), cavities (voids and bubbles), the crystalline-to-amorphous transition, and the phase transformation from fluorite to pyrochlore structure. The ion irradiation-induced amorphization mechanism, the retention ability of the fission products, and structural stability of YSZ are discussed in terms of ion incorporation effects, implanted ion radii, and the solubility limits of the ions in the matrix.

  17. Effects of Straw Incorporation on Soil Organic Matter and Soil Water-Stable Aggregates Content in Semiarid Regions of Northwest China

    PubMed Central

    Jia, Zhikuan; Han, Qingfang; Ren, Xiaolong; Li, Yongping

    2014-01-01

    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

  18. Ultrasonically assisted drilling: A finite-element model incorporating acoustic softening effects

    NASA Astrophysics Data System (ADS)

    Phadnis, V. A.; Roy, A.; Silberschmidt, V. V.

    2013-07-01

    Ultrasonically assisted drilling (UAD) is a novel machining technique suitable for drilling in hard-to-machine quasi-brittle materials such as carbon fibre reinforced polymer composites (CFRP). UAD has been shown to possess several advantages compared to conventional drilling (CD), including reduced thrust forces, diminished burr formation at drill exit and an overall improvement in roundness and surface finish of the drilled hole. Recently, our in-house experiments of UAD in CFRP composites demonstrated remarkable reductions in thrust-force and torque measurements (average force reductions in excess of 80%) when compared to CD with the same machining parameters. In this study, a 3D finite-element model of drilling in CFRP is developed. In order to model acoustic (ultrasonic) softening effects, a phenomenological model, which accounts for ultrasonically induced plastic strain, was implemented in ABAQUS/Explicit. The model also accounts for dynamic frictional effects, which also contribute to the overall improved machining characteristics in UAD. The model is validated with experimental findings, where an excellent correlation between the reduced thrust force and torque magnitude was achieved.

  19. Experimental test of new theoretical models for the electrokinetic properties of biological membranes. The effect of UO/sup 2 + +/ and tetracaine on the electrophoretic mobility of bilayer membranes and human erythrocytes

    SciTech Connect

    Pasquale, L.; Winiski, A.; Oliva, C.; Vaio, G.; McLaughlin, S.

    1986-12-01

    For a large smooth particle with charges at the surface, the electrophoretic mobility is proportional to the zeta potential, which is related to the charge density by the Gouy-Chapman theory of the diffuse double layer. This classical model adequately describes the dependence of the electrophoretic mobility of phospholipid vesicles on charge density and salt concentration, but it is not applicable to most biological cells, for which new theoretical models have been developed. We tested these new models experimentally by measuring the effect of UO/sup 2 + +/ on the electrophoretic mobility of model membranes and human erythrocytes in 0.15 M NaCl at pH 5. We used UO/sup 2 + +/ for these studies because it should adsorb specifically to the bilayer surface of the erythrocyte and should not change the density of fixed charges in the glycocalyx. Our experiments demonstrate that it forms high-affinity complexes with the phosphate groups of several phospholipids in a bilayer but does not bind significantly to sialic acid residues. As observed previously, UO/sup 2 + +/ adsorbs strongly to egg phosphatidylcholine (PC) vesicles: 0.1 mM UO/sup 2 + +/ changes the zeta potential of PC vesicles from 0 to +40 mV. It also has a large effect on the electrophoretic mobility of vesicles formed from mixtures of PC and the negative phospholipid phosphatidylserine (PS): 0.1 mM UO/sup 2 + +/ changes the zeta potential of PC/PS vesicles (10 mol % PS) from -13 to +37 mV. In contrast, UO/sup 2 + +/ has only a small effect on the electrophoretic mobility of either vesicles formed from mixtures of PC and the negative ganglioside GM1 or erythrocytes: 0.1 mM UO/sup 2 + +/ changes the apparent zeta potential of PC/GM1 vesicles (17 mol % GM1) from -11 to +5 mV and the apparent zeta potential of erythrocytes from -12 to -4 mV.

  20. Micro and nanoscale electrochemical systems for reagent generation, coupled electrokinetic transport and enhanced detection

    NASA Astrophysics Data System (ADS)

    Contento, Nicholas M.

    Chemical analysis is being performed in devices operated at ever decreasing length scales in order to harness the fundamental benefits of micro and nanoscale phenomena while minimizing operating footprint and sample size. The advantages of moving traditional sample or chemical processing steps (e.g. separation, detection, and reaction) into micro- and nanofluidic devices have been demonstrated, and they arise from the relatively rapid rates of heat and mass transport at small length scales. The use of electrochemical methods in micro/nanoscale systems to control and improve these processes holds great promise. Unfortunately, much is still not understood about the coupling of multiple electrode driven processes in a confined environment nor about the fundamental changes in device performance that occur as geometries approach the nanoscale regime. At the nanoscale a significant fraction of the sample volume is in close contact with the device surface, i.e. most of the sample is contained within electronic or diffusion layers associated with surface charge or surface reactions, respectively. The work presented in this thesis aims to understand some fundamental different behaviors observed in micro/nanofluidic structures, particularly those containing one or more embedded, metallic electrode structures. First, a quantitative method is devised to describe the impact of electric fields on electrochemistry in multi-electrode micro/nanofluidic systems. Next the chemical manipulation of small volumes (? 10-13 L) in micro/nanofluidic structures is explored by creating regions of high pH and high dissolved gas (H 2) concentration through the electrolysis of H2O. Massively parallel arrays of nanochannel electrodes, or embedded annular nanoband electrodes (EANEs), are then studied with a focus on achieving enhanced signals due to coupled electrokinetic and electrochemical effects. In EANE devices, electroosmotic flow results from the electric field generated between the closely spaced working and counter electrode, causing beneficial convective transport to the electrode surface. Finally, redox cycling of electroactive species at recessed ring-disk nanoelectrode arrays is described with a focus on the use of finite element calculations to predict electrode performance as a function of electrode geometry. The improved understanding of electrochemistry, electrokinetics and mass transport in micrometer and nanometer scale structures presented in this thesis should guide the development of next-generation devices for combinatorial processing involving electrochemical analysis, reagent generation and heterogeneous reaction.

  1. Transient electrokinetic transport in micro/nanofluidic systems with sudden expansion and contraction cross sections

    NASA Astrophysics Data System (ADS)

    Chein, Reiyu; Liao, Yuchung

    2013-03-01

    This study numerically investigates electrokinetic transport in a micro/nanofluidic system by solving the transient Poisson, Nernst-Planck, and Navier-Stokes equations simultaneously. The considered system is a nanochannel connected to two micro channels at its ends. Under various applied electric potential biases, the concentration polarization effect on the fluid flow, induced pressure, and electric current is examined. By comparing with the Donnan equilibrium condition and electroosmotic flow in the microscale dimension, electric body force due to non-zero charge density is the mechanism for producing vortex flow and inducing a positive pressure gradient on the anodic side of the system. The diffusive boundary layer thickness is reduced due to stirring by the generated vortex flow, resulting in over-limiting current when the applied electric potential bias is high. The steady-state current voltage curve indicates that in the Ohmic regime, higher current can be obtained when the surface charge density is large due to higher fluid velocity. In the limiting and over-limiting current regimes, higher electric current can be obtained when the nanochannel is larger with smaller surface density because more ions are available for carrying the current. The nanochannel size effect on the limiting and over-limiting current magnitudes is insignificant when the surface charge density is large.

  2. Dotgain estimation using linear least squares incorporating neighboring and clustering effects

    NASA Astrophysics Data System (ADS)

    Stamm, T.; Simon, K.

    2009-01-01

    This work presents a model for dotgain prediction using repetitive patterns based on the characterization of neighboring and clustering effects of a specific printing device. Estimating dotgain is done nowadays by measuring patches of color patterns realized by a specific printing device. Current models use the information about adjacent dots to predict dotgain. However, research has shown that dotgain is influenced by the neighborhood of a dot which in general is bigger than one dot-size, in particular in connection with laser printers. The presented method predicts the dotgain of a dot considering a larger surrounding based on the observation of two main parameters affecting the luminance of a pattern which can be fitted using linear regression.

  3. On incorporating damping and gravity effects in models of structural dynamics of the SCOLE configuration

    NASA Technical Reports Server (NTRS)

    Taylor, Larry; Leary, Terry; Stewart, Eric

    1987-01-01

    The damping for structural dynamic models of flexible spacecraft is usually ignored and then added after modal frequencies and mode shapes are calculated. It is common practice to assume the same damping ratio for all modes, although it is known that damping due to bending and that due to torsion are sometimes ignored. Two methods of including damping in the modeling process from its onset are examined. First, the partial derivative equations of motion are analyzed for a pinned-pinned beam with damping. The end conditions are altered to handle bodies with mass and inertia for the Spacecraft Control Laboratory Experiment (SCOLE) configuration. Second, a massless beam approximation is used for the modes with low frequencies, and a clamped-clamped system is used to approximate the modes for arbitrarily high frequency. The model is then modified to include gravity effects and is compared with experimental results.

  4. Incorporating Cache Management Behavior into Seed Dispersal: The Effect of Pericarp Removal on Acorn Germination

    PubMed Central

    Yi, Xianfeng; Zhang, Mingming; Bartlow, Andrew W.; Dong, Zhong

    2014-01-01

    Selecting seeds for long-term storage is a key factor for food hoarding animals. Siberian chipmunks (Tamias sibiricus) remove the pericarp and scatter hoard sound acorns of Quercus mongolica over those that are insect-infested to maximize returns from caches. We have no knowledge of whether these chipmunks remove the pericarp from acorns of other species of oaks and if this behavior benefits seedling establishment. In this study, we tested whether Siberian chipmunks engage in this behavior with acorns of three other Chinese oak species, Q. variabilis, Q. aliena and Q. serrata var. brevipetiolata, and how the dispersal and germination of these acorns are affected. Our results show that when chipmunks were provided with sound and infested acorns of Quercus variabilis, Q. aliena and Q. serrata var. brevipetiolata, the two types were equally harvested and dispersed. This preference suggests that Siberian chipmunks are incapable of distinguishing between sound and insect-infested acorns. However, Siberian chipmunks removed the pericarp from acorns of these three oak species prior to dispersing and caching them. Consequently, significantly more sound acorns were scatter hoarded and more infested acorns were immediately consumed. Additionally, indoor germination experiments showed that pericarp removal by chipmunks promoted acorn germination while artificial removal showed no significant effect. Our results show that pericarp removal allows Siberian chipmunks to effectively discriminate against insect-infested acorns and may represent an adaptive behavior for cache management. Because of the germination patterns of pericarp-removed acorns, we argue that the foraging behavior of Siberian chipmunks could have potential impacts on the dispersal and germination of acorns from various oak species. PMID:24647670

  5. Incorporation of Mean Stress Effects into the Micromechanical Analysis of the High Strain Rate Response of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  6. A two-scale non-local model of swelling porous media incorporating ion size correlation effects

    NASA Astrophysics Data System (ADS)

    Le, T. D.; Moyne, C.; Murad, M. A.; Lima, S. A.

    2013-12-01

    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.

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

    SciTech Connect

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

    2014-06-16

    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 C{sub 60}. 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.

  8. Incorporating the effect of fractionation in the evaluation of proton plan robustness to setup errors.

    PubMed

    Lowe, Matthew; Albertini, Francesca; Aitkenhead, Adam; Lomax, Antony J; MacKay, Ranald I

    2016-01-01

    To ensure the safe delivery of proton therapy treatments it is important to evaluate the effect of potential uncertainties, such as patient mispositioning, on the intended dose distribution. However, it can be expected that the uncertainty resulting from patient positioning is reduced in a fractionated treatment due to the convergence of random variables with the delivery of repeated treatments. This is neglected by current approaches to robustness analysis resulting in an overly conservative assessment of the robustness which can lead to sub-optimal plans. Here, a fast method of accounting for this reduced uncertainty is presented. An estimated bound to the error in the dose distribution resulting from setup uncertainty over a specified number of fractions is calculated by considering the distribution of values for each voxel across 14 initial error scenarios. The bound on the error in a given voxel is estimated using a 99.9% confidence limit assuming a convergence towards a normal distribution in line with the central limit theorem, and a correction of [Formula: see text] accounting for the reduction in the standard deviation over n fractions. The proposed method was validated in 5 patients by comparison to Monte Carlo simulations of 300 treatment courses. A voxelwise and volumetric analysis of the estimated and simulated bounds to the uncertainty in the dose distribution demonstrate that the proposed technique can be used to assess proton plan robustness more accurately allowing for less conservative treatment plans. PMID:26675133

  9. A Novel Nanoprobe for Multimodal Imaging Is Effectively Incorporated into Human Melanoma Metastatic Cell Lines.

    PubMed

    Aasen, Synnøve Nymark; Pospisilova, Aneta; Eichler, Tilo Wolf; Panek, Jiri; Hruby, Martin; Stepanek, Petr; Spriet, Endy; Jirak, Daniel; Skaftnesmo, Kai Ove; Thorsen, Frits

    2015-01-01

    To facilitate efficient drug delivery to tumor tissue, several nanomaterials have been designed, with combined diagnostic and therapeutic properties. In this work, we carried out fundamental in vitro and in vivo experiments to assess the labeling efficacy of our novel theranostic nanoprobe, consisting of glycogen conjugated with a red fluorescent probe and gadolinium. Microscopy and resazurin viability assays were used to study cell labeling and cell viability in human metastatic melanoma cell lines. Fluorescence lifetime correlation spectroscopy (FLCS) was done to investigate nanoprobe stability. Magnetic resonance imaging (MRI) was performed to study T? relaxivity in vitro, and contrast enhancement in a subcutaneous in vivo tumor model. Efficient cell labeling was demonstrated, while cell viability, cell migration, and cell growth was not affected. FLCS showed that the nanoprobe did not degrade in blood plasma. MRI demonstrated that down to 750 cells/?L of labeled cells in agar phantoms could be detected. In vivo MRI showed that contrast enhancement in tumors was comparable between Omniscan contrast agent and the nanoprobe. In conclusion, we demonstrate for the first time that a non-toxic glycogen-based nanoprobe may effectively visualize tumor cells and tissue, and, in future experiments, we will investigate its therapeutic potential by conjugating therapeutic compounds to the nanoprobe. PMID:26370983

  10. Effect of incorporation of Moringa oleifera leaves extract on quality of ground pork patties.

    PubMed

    Muthukumar, M; Naveena, B M; Vaithiyanathan, S; Sen, A R; Sureshkumar, K

    2014-11-01

    Present study was conducted to evaluate the effect of addition of different levels of Moringa oleifera leaves extract (MLE) and butylated hydroxytoluene (BHT) in raw and cooked pork patties during refrigerated storage. Five treatments evaluated include: Control (without MLE/BHT), MLE 300 (300 ppm equivalent M. oleifera leaves phenolics), MLE 450 (450 ppm equivalent M. oleifera leaves phenolics), MLE 600 (600 ppm equivalent M. oleifera leaves phenolics) and BHT 200 (200 ppm BHT). Total phenolic content ranged from 60.78 to 70.27 mg per gram. A concentration dependent increase in reducing power and 1,1-diphenyl 2-picrylhydrazyl (DPPH) radical scavenging activity of both MLE and BHT was noticed. Higher (P?

  11. Effect of transglutaminase on properties of tilapia scale gelatin films incorporated with soy protein isolate.

    PubMed

    Weng, Wuyin; Zheng, Huibin

    2015-02-15

    The effect of transglutaminase (TGase) on the properties of tilapia scale gelatin films in the presence of soy protein isolate (SPI) was investigated. When 3% TGase was added into gelatin films, the total soluble matter and protein solubility of films were decreased from 89.36% and 92.78% to 35.83% and 40.05%, respectively, and the decline was promoted by adding 5% SPI. The strength of the films was increased by adding 1% TGase irrespective of SPI addition, but decreased when the TGase concentration was further raised. No obvious colour change was observed in the films with or without TGase and SPI. Based on the results of SDS-PAGE, DSC and SEM, it was revealed that the movement of low molecular weight hydrophilic protein was depressed by the cross-linking network structure induced by TGase and SPI during film drying, indicating that adding SPI is essential to improve the thermal stability and water resistance properties of TGase-induced gelatin films. PMID:25236224

  12. Effect of annealing on graphene incorporated poly-(3-hexylthiophene):CuInS2 photovoltaic device

    NASA Astrophysics Data System (ADS)

    Kumari, Anita; Singh, Inderpreet; Dixit, Shiv Kumar

    2014-10-01

    The effect of thermal annealing on the power conversion efficiency (PCE) of poly(3-hexylthiophene) (P3HT):CuInS2 quantum dot:graphene photovoltaic device has been studied by analyzing optical characteristics of composite films and electrical characteristics of the device with structure indium tin oxide/poly[ethylene dioxythiophene]:poly[styrene sulfonate] (ITO/PEDOT:PSS)/P3HT:CIS:graphene/LiF/aluminum. It was observed that after annealing at 120°C for 15 min a typical device containing 0.005 % w/w of graphene shows the best performance with a PCE of 1.3%, an open-circuit voltage of 0.44V, a short-circuit current density of 7.6 mA/cm2, and a fill factor of 0.39. It is observed that the thermal annealing considerably enhances the efficiency of solar cells. However, an annealing at higher temperature such as at 140°C results in a decrease in the device efficiency.

  13. A Novel Nanoprobe for Multimodal Imaging Is Effectively Incorporated into Human Melanoma Metastatic Cell Lines

    PubMed Central

    Aasen, Synnøve Nymark; Pospisilova, Aneta; Eichler, Tilo Wolf; Panek, Jiri; Hruby, Martin; Stepanek, Petr; Spriet, Endy; Jirak, Daniel; Skaftnesmo, Kai Ove; Thorsen, Frits

    2015-01-01

    To facilitate efficient drug delivery to tumor tissue, several nanomaterials have been designed, with combined diagnostic and therapeutic properties. In this work, we carried out fundamental in vitro and in vivo experiments to assess the labeling efficacy of our novel theranostic nanoprobe, consisting of glycogen conjugated with a red fluorescent probe and gadolinium. Microscopy and resazurin viability assays were used to study cell labeling and cell viability in human metastatic melanoma cell lines. Fluorescence lifetime correlation spectroscopy (FLCS) was done to investigate nanoprobe stability. Magnetic resonance imaging (MRI) was performed to study T1 relaxivity in vitro, and contrast enhancement in a subcutaneous in vivo tumor model. Efficient cell labeling was demonstrated, while cell viability, cell migration, and cell growth was not affected. FLCS showed that the nanoprobe did not degrade in blood plasma. MRI demonstrated that down to 750 cells/?L of labeled cells in agar phantoms could be detected. In vivo MRI showed that contrast enhancement in tumors was comparable between Omniscan contrast agent and the nanoprobe. In conclusion, we demonstrate for the first time that a non-toxic glycogen-based nanoprobe may effectively visualize tumor cells and tissue, and, in future experiments, we will investigate its therapeutic potential by conjugating therapeutic compounds to the nanoprobe. PMID:26370983

  14. Incorporating the effect of DEM resolution and accuracy for improved flood inundation mapping

    NASA Astrophysics Data System (ADS)

    Saksena, Siddharth; Merwade, Venkatesh

    2015-11-01

    Topography plays a major role in determining the accuracy of flood inundation areas. However, many areas in the United States and around the world do not have access to high quality topographic data in the form of Digital Elevation Models (DEM). For such areas, an improved understanding of the effects of DEM properties such as horizontal resolution and vertical accuracy on flood inundation maps may eventually lead to improved flood inundation modeling and mapping. This study attempts to relate the errors arising from DEM properties such as spatial resolution and vertical accuracy to flood inundation maps, and then use this relationship to create improved flood inundation maps from coarser resolution DEMs with low accuracy. The results from the five stream reaches used in this study show that water surface elevations (WSE) along the stream and the flood inundation area have a linear relationship with both DEM resolution and accuracy. This linear relationship is then used to extrapolate the water surface elevations from coarser resolution DEMs to get water surface elevations corresponding to a finer resolution DEM. Application of this approach show that improved results can be obtained from flood modeling by using coarser and less accurate DEMs, including public domain datasets such as the National Elevation Dataset and Shuttle Radar Topography Mission (SRTM) DEMs. The improvement in the WSE and its application to obtain better flood inundation maps is dependent on the study reach characteristics such as land use, valley shape, reach length and width. Application of the approach presented in this study on more reaches may lead to development of guidelines for flood inundation mapping using coarser resolution and less accurate topographic datasets.

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

    SciTech Connect

    Fan, Donghua; Zhang, Rong; Wang, Xianghu

    2011-04-15

    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.

  16. Effect of Glass Fiber Incorporation on Flexural Properties of Experimental Composites

    PubMed Central

    Fonseca, Rodrigo Borges; Marques, Aline Silva; Bernades, Karina de Oliveira; Carlo, Hugo Lemes; Naves, Lucas Zago

    2014-01-01

    This study evaluated the effect of fiber addiction in flexural properties of 30?wt% silica filled BisGMA resin (FR) or unfilled Bis-GMA (UR). Ten groups were created (N = 10) varying the resin (FR or UR) and quantity of glass fibers (wt%: 0, 10, 15, 20, and 30). Samples (10?×?2?×?1?mm) were submitted to flexural strength test following SEM examination. Data were analyzed by two-way ANOVA, Tukey, and Student t-test (? = 0.05). Results for flexural strength (MPa) were FR-groups: 0% (442.7 ± 140.6)C, 10% (772.8 ± 446.3)ABC, 15% (854.7 ± 297.3)AB, 20% (863.4 ± 418.0)A, 30% (459.5 ± 140.5)BC; UR-groups: 0% (187.7 ± 120.3)B, 10% (795.4 ± 688.1)B, 15% (1999.9 ± 1258.6)A, 20% (1911.5 ± 596.8)A, and 30% (2090.6 ± 656.7)A, and for flexural modulus (GPa) FR-groups: 0% (2065.63 ± 882.15)B, 10% (4479.06 ± 3019.82)AB, 15% (5694.89 ± 2790.3)A, 20% (6042.11 ± 3392.13)A, and 30% (2495.67 ± 1345.86)B; UR-groups: 0% (1090.08 ± 708.81)C, 10% (7032.13 ± 7864.53)BC, 15% (19331.57 ± 16759.12)AB, 20% (15726.03 ± 8035.09)AB, and 30% (29364.37 ± 13928.96)A. Fiber addiction in BisGMA resin increases flexural properties, and the interaction between resin and fibers seems better in the absence of inorganic fillers increasing flexural properties. PMID:25136595

  17. Effects of Non-Natural Amino Acid Incorporation into the Enzyme Core Region on Enzyme Structure and Function

    PubMed Central

    Wong, H. Edward; Kwon, Inchan

    2015-01-01

    Techniques to incorporate non-natural amino acids (NNAAs) have enabled biosynthesis of proteins containing new building blocks with unique structures, chemistry, and reactivity that are not found in natural amino acids. It is crucial to understand how incorporation of NNAAs affects protein function because NNAA incorporation may perturb critical function of a target protein. This study investigates how the site-specific incorporation of NNAAs affects catalytic properties of an enzyme. A NNAA with a hydrophobic and bulky sidechain, 3-(2-naphthyl)-alanine (2Nal), was site-specifically incorporated at six different positions in the hydrophobic core of a model enzyme, murine dihydrofolate reductase (mDHFR). The mDHFR variants with a greater change in van der Waals volume upon 2Nal incorporation exhibited a greater reduction in the catalytic efficiency. Similarly, the steric incompatibility calculated using RosettaDesign, a protein stability calculation program, correlated with the changes in the catalytic efficiency. PMID:26402667

  18. Thrombin Production and Human Neutrophil Elastase Sequestration by Modified Cellulosic Dressings and Their Electrokinetic Analysis

    PubMed Central

    Edwards, Judson Vincent; Prevost, Nicolette

    2011-01-01

    Wound healing is a complex series of biochemical and cellular events. Optimally, functional material design addresses the overlapping acute and inflammatory stages of wound healing based on molecular, cellular, and bio-compatibility issues. In this paper the issues addressed are uncontrolled hemostasis and inflammation which can interfere with the orderly flow of wound healing. In this regard, we review the serine proteases thrombin and elastase relative to dressing functionality that improves wound healing and examine the effects of charge in cotton/cellulosic dressing design on thrombin production and elastase sequestration (uptake by the wound dressing). Thrombin is central to the initiation and propagation of coagulation, and elastase is released from neutrophils that can function detrimentally in a stalled inflammatory phase characteristic of chronic wounds. Electrokinetic fiber surface properties of the biomaterials of this study were determined to correlate material charge and polarity with function relative to thrombin production and elastase sequestration. Human neutrophil elastase sequestration was assessed with an assay representative of chronic wound concentration with cotton gauze cross-linked with three types of polycarboxylic acids and one phosphorylation finish; thrombin production, which was assessed in a plasma-based assay via a fluorogenic peptide substrate, was determined for cotton, cotton-grafted chitosan, chitosan, rayon/polyester, and two kaolin-treated materials including a commercial hemorrhage control dressing (QuickClot Combat Gauze). A correlation in thrombin production to zeta potential was found. Two polycarboxylic acid cross linked and a phosphorylated cotton dressing gave high elastase sequestration. PMID:24956451

  19. Simultaneous determination of five phytohormones in mungbean sprouts of China by micellar electrokinetic chromatography.

    PubMed

    Sun, Yue-Na; Qin, Xin-Ying; Lv, Yun-Kai; Li, Shan-Ze; Wei, Chen

    2014-08-01

    A simple and rapid micellar electrokinetic chromatography method was developed for simultaneous determination of indole-3-acetic acid, indole-3-butyric acid, gibberellic acid, abscisic acid and naphthylacetic acid in mungbean sprouts for monitoring plant growth and development. The effects of several parameters related to the separation and determination were investigated in detail. The analysis was carried out using 10 mM borax, 10 mM sodium dihydrogen phosphate, 90 mM sodium dodecyl sulfate and 5% acetonitrile as running buffer (pH 9.0). Under optimum conditions, the method demonstrated good performance concerning linearity (r, 0.9954-0.9991), precision (0.77-4.97%), the method limit of detection (LOD) and the method limit of quantitation (LOQ) (LOD, 0.011-0.177 mg/kg; LOQ, 0.035-0.590 mg/kg) and accuracy (83.62-102.56%). The results confirmed that the method is rapid, convenient and of low cost for the determination of the phytohormones. PMID:23845886

  20. Holistic Analysis of Seven Active Ingredients by Micellar Electrokinetic Chromatography from Three Medicinal Herbs Composing Shuanghuanglian.

    PubMed

    Zhou, Xian-Jing; Chen, Juan; Li, Ying-Dong; Jin, Ling; Shi, Yan-Ping

    2015-11-01

    A simple and reliable method has been developed with a new strategy named holistic analysis of multiple constituents to evaluate the quality of the well-known traditional Chinese medicine (TCM) Shuanghuanglian (SHL) oral liquid and soft capsule. Seven main constituents of the medicine, i.e., baicalein, baicalin, chlorogenic acid, wogonin, scutellarin, forsythin and hyperin, were selected as the evaluation markers and analyzed by micellar electrokinetic chromatography. The effects of buffer pH, concentration of electrolyte, organic modifier and applied voltage on migration behavior were studied systematically. The optimum conditions for the separation were achieved in a 12.5 mM borate-10 mM sodium dihydrogen phosphate-10 mM sodium dodecyl sulfate buffer at pH 9.1 containing 10% (v/v) acetonitrile under 15 kV. The analytes were identified by their relative time with regard to para-hydroxybenzoic acid migration time used as an internal standard. The method was validated in terms of linearity, limit of detection and quantification, precision, accuracy and recoveries. The correlation coefficient ranged from 0.9962 to 0.9992. The limits of detection (S/N = 3) were from 0.15 to 3.95 ?g mL(-1). Recoveries of seven analytes in the SHL samples ranged from 89.00 to 103.04%. The proposed method was successfully applied for the quality control of complicated TCM SHL. PMID:26060213

  1. [Determination of benzene, toluene and xylene in marine sediment samples by micellar electrokinetic capillary chromatography].

    PubMed

    Wang, S H; Shi, X Y; Ma, W Y; Chen, D Y; Liu, J A

    2000-01-01

    The analysis and determination of the contents of benzene series compounds in marine sediment are important in chemical exploration of petroleum resources. In the present study a method has been developed for this purpose by using micellar electrokinetic capillary chromatography (MECC). A fused silica capillary of 45 cm x 75 microns i.d. (effective length 40 cm) was used. Running buffer was 2 mmol/L aqueous solution of sodium tetraborate containing 75 mmol/L sodium dodecyl sulfate (pH 9.16) and 20% methanol. The applied voltage was 25 kV and detection wavelength was 200 nm. The benzene, toluene and xylene were separated well within 20 min. Peak area was used for quantitative analysis. The calibration curves were linear in the range 4-50 mg/L. The relative standard deviation was within 6.2%. The contents of benzene series in sediments were between 3.79 and 17.36 micrograms/g. PMID:12541464

  2. Simultaneous determination of lovastatin and citrinin in red yeast rice supplements by micellar electrokinetic capillary chromatography.

    PubMed

    Nigovi?, Biljana; Serti?, Miranda; Mornar, Ana

    2013-05-01

    Lovastatin is a main component of Monascus purpureus fermented red rice contributing to the lipid-lowering effect. Citrinin is a toxic fermentation by-product which can be found as a contaminant. An accurate, simple and rapid micellar electrokinetic capillary chromatographic method was developed for the first time for simultaneous determination of lovastatin present in lactone and hydroxy acid forms and citrinin in red rice products provided by different manufacturers and formulated in various dosage forms. Separation was achieved within only 2 min using 20 mM of phosphate buffer at pH 7.0 and 30 mM of sodium dodecyl sulphate at an applied voltage of 25 kV. Sensitivity crucial for detecting citrinin was enhanced by using an extended light path capillary. The results showed that the content of lovastatin and its acid form in dietary supplements were considerably different indicating the need for improved standardization in order to ensure efficiency and safety of these products. PMID:23265521

  3. Mixing of non-Newtonian fluids in wavy serpentine microchannel using electrokinetically driven flow.

    PubMed

    Cho, Ching-Chang; Chen, Chieh-Li; Chen, Cha'o-Kuang

    2012-03-01

    A numerical investigation is performed into the mixing performance of electrokinetically driven non-Newtonian fluids in a wavy serpentine microchannel. The flow behavior of the non-Newtonian fluids is described using a power-law model. The simulations examine the effects of the flow behavior index, the wave amplitude, the wavy-wall section length, and the applied electric field strength on the mixing performance. The results show that the volumetric flow rate of shear-thinning fluids is higher than that of shear-thickening fluids, and therefore results in a poorer mixing performance. It is shown that for both types of fluid, the mixing performance can be enhanced by increasing the wave amplitude, extending the length of the wavy-wall section, and reducing the strength of the electric field. Thus, although the mixing efficiency of shear-thinning fluids is lower than that of shear-thickening fluids, the mixing performance can be improved through an appropriate specification of the flow and geometry parameters. For example, given a shear-thinning fluid with a flow behavior index of 0.8, a mixing efficiency of 87% can be obtained by specifying the wave amplitude as 0.7, the wavy-wall section length as five times the characteristic length, the nondimensional Debye-Huckel parameter as 100, and the applied electric field strength as 43.5 V/cm. PMID:22522530

  4. Recovery of Drug Delivery Nanoparticles from Human Plasma Using an Electrokinetic Platform Technology.

    PubMed

    Ibsen, Stuart; Sonnenberg, Avery; Schutt, Carolyn; Mukthavaram, Rajesh; Yeh, Yasan; Ortac, Inanc; Manouchehri, Sareh; Kesari, Santosh; Esener, Sadik; Heller, Michael J

    2015-10-01

    The effect of complex biological fluids on the surface and structure of nanoparticles is a rapidly expanding field of study. One of the challenges holding back this research is the difficulty of recovering therapeutic nanoparticles from biological samples due to their small size, low density, and stealth surface coatings. Here, the first demonstration of the recovery and analysis of drug delivery nanoparticles from undiluted human plasma samples through the use of a new electrokinetic platform technology is presented. The particles are recovered from plasma through a dielectrophoresis separation force that is created by innate differences in the dielectric properties between the unaltered nanoparticles and the surrounding plasma. It is shown that this can be applied to a wide range of drug delivery nanoparticles of different morphologies and materials, including low-density nanoliposomes. These recovered particles can then be analyzed using different methods including scanning electron microscopy to monitor surface and structural changes that result from plasma exposure. This new recovery technique can be broadly applied to the recovery of nanoparticles from high conductance fluids in a wide range of applications. PMID:26274918

  5. Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

    DOEpatents

    Ramirez, A.L.; Cooper, J.F.; Daily, W.D.

    1996-02-27

    This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination. 1 fig.

  6. Using electrokinetic phenomena and electrical resistance tomography to characterize the movement of subsurface fluids

    DOEpatents

    Ramirez, Abelardo L. (Pleasanton, CA); Cooper, John F. (Oakland, CA); Daily, William D. (Livermore, CA)

    1996-01-01

    This invention relates generally to the remote detections of subsurface liquid contaminants using in combination a geophysical technique known as ERT and an EKS. Electrokinetic transport is used to enhance the ability of electrical resistance tomography (ERT) to detect position and movement of subsurface contaminant liquids, particles or ions. ERT images alone are difficult to interpret because of natural inhomogeneities in soil composition and electrical properties. By subtracting two or more ERT images obtained before and after field induced movement, a high contrast image of a plume of distinct electrokinetic properties can be seen. The invention is applicable to important subsurface characterization problems including, as examples, (1) detection of liquid-saturated plumes of contaminants such as those associated with leaks from underground storage tanks containing hazardous concentrated electrolytes, (2) detection and characterization of soils contaminated with organic pollutants such as droplets of gasoline; and (3) monitoring the progress of electrokinetic containment or clean up of underground contamination.

  7. Enhanced electrokinetic treatment of different marine sediments contaminated by heavy metals.

    PubMed

    De Gioannis, Giorgia; Muntoni, Aldo; Polettini, Alessandra; Pomi, Raffaella

    2008-07-01

    In the present work, the application of an assisted electrokinetic process for the removal of heavy metals from real contaminated sediments was investigated. The process made use of both chemical and physical methods, including addition of chelating and acid agents, as well as application of a hydraulic gradient. Lab-scale electrokinetic runs were applied on two different dredged sediments varying the applied voltage gradient and the treatment duration. The use of EDTA significantly improved the overall performance of the electrokinetic treatment for sediment V (more than 60% mobilized for each metal), while only aggressive acid conditioning with nitric acid was able to remove significant amounts of heavy metals (up to 40.5% for Pb) from sediment S due to the strong buffering capacity of this material. This clearly assesses that the specific characteristics of the materials under concern and the reactions occurring at the electrodes must be carefully evaluated when applying an electroremediation process. PMID:18569295

  8. Incorporation of lapatinib into human serum albumin nanoparticles with enhanced anti-tumor effects in HER2-positive breast cancer.

    PubMed

    Wan, Xu; Zheng, Xiaoyao; Pang, Xiaoying; Zhang, Zheming; Zhang, Qizhi

    2015-12-01

    Lapatinib, a selective small-molecule dual-tyrosine kinase inhibitor of HER2 and EGFR, is effective in HER2-positive patients with advanced metastatic breast cancer. However, its low and variable oral absorption, large required daily dose and serious gastrointestinal side effects all limit its clinical use. Intravenous administration offers a good option to overcome these disadvantages. However, the poor solubility of lapatinib in water and organic solvents causes lapatinib to fail in a common injectable preparation. Considering lapatinib's high albumin binding ability (>99%), in this study, we developed human serum albumin nanoparticles loaded with lapatinib (LHNPs) by Nab technology for intravenous administration and investigated its efficacy against HER2-positive breast cancer. Raman shift, X-ray diffraction and X-ray photoelectron spectroscopy studies demonstrated that lapatinib was successfully incorporated into nanoparticles, and LHNPs exhibited good stability and sustained-release effect in vitro. LHNPs could be effectively taken up by SKBr3 cells in a concentration- and time-dependent manner, and the uptake was mediated by energy-dependent endocytosis, which involved clathrin-dependent pinocytosis. Furthermore, in vitro and in vivo data indicated that LHNPs presented the strong ability to induce apoptosis and superior anti-tumor efficacy in tumor-bearing mice to the commercial tablet Tykerb through the inhibition of HER2 phosphorylation. Subchronic toxicity assays indicated that LHNPs had no hepatic or kidney toxicity. With mature technology for industrial production and enhanced therapeutic effects, LHNPs are likely to have great potential as a safe therapeutic candidate against HER2-positive breast cancer in the clinic. PMID:26539808

  9. Propagation of electro-kinetic waves in magnetized GaN semiconductor with nano-sized ion colloids

    NASA Astrophysics Data System (ADS)

    Saxena, Ajay; Sharma, Giriraj; Jat, K. L.; Rishi, M. P.

    2015-07-01

    Based on hydrodynamic model of multi-component plasma, an analytical study on propagation of longitudinal electro-kinetic (LEK) waves in wurtzite and zincblende structures of GaN is carried out. Nano-sized ion colloids (NICs) are embedded in the sample by the technique of ion-implantation. The implanted NICs are considered massive by an order as compared to the host lattice points and do not participate in Based LEK perturbations. Though, the NICs are continuously bombarded by the electrons as well as the holes yet, the former acquires a net negative charge owing to relatively higher mobility of electrons and consequently results into depletion of electron density in the medium. It i s found that the presence of charged NICs significantly modifies the dispersion and amplification characteristics of LEK waves in magnetized GaN semiconductor plasma and their role becomes increasingly effective as the fraction of charge on them increases.

  10. Analysis of in vitro oxidized human LDL phospholipids by solid-phase extraction and micellar electrokinetic capillary chromatography.

    PubMed

    Yang, Ying-Ling; Chong, Chin-Pong; Tsai, Ming-Hua; Liu, Mine-Yine

    2012-04-01

    Phospholipids of in vitro oxidized human low-density lipoproteins (LDL) were separated by two different solid-phase extraction (SPE) methods. One of the two methods was designed to test the effects of gradient elution. This SPE method isolated more phospholipids from in vitro oxidized LDL than the other one according to the results of liquid chromatography and electrospray ionization mass spectrometry (LC ESI-MS) analysis. A micellar electrokinetic capillary chromatography (MEKC) method was also used to analyze phospholipids separated by SPE. The results of MEKC and LC ESI-MS were consistent for the major phospholipid classes, including PC, lysoPC, PE, PI and PS. The MEKC profiles showed significant differences for native and oxidized LDL phospholipids. Therefore, the unique combination of SPE and MEKC methods showed dramatic distinctions between native and in vitro oxidized human LDL phospholipids. The combination also shows great potential for rapid analysis of in vivo oxidized human LDL phospholipids in the future. PMID:22392513

  11. Enhanced transport of materials into enamel nanopores via electrokinetic flow.

    PubMed

    Gan, H Y; Sousa, F B; Carlo, H L; Maciel, P P; Macena, M S; Han, J

    2015-04-01

    The ability to infiltrate various molecules and resins into dental enamel is highly desirable in dentistry, yet transporting materials into dental enamel is limited by the nanometric scale of their pores. Materials that cannot be infiltrated into enamel by diffusion/capillarity are often considered molecules with sizes above a critical threshold, which are often considered to be larger than the pores of enamel. We challenge this notion by reporting the use of electrokinetic flow to transport solutions with molecules with sizes above a critical threshold-namely, an aqueous solution with a high refractive index (Thoulet's solution) and a curable fluid resin infiltrant (without acid etching)-deep into the normal enamel layer. Volume infiltration by Thoulet's solution is increased by 5- to 6-fold, and resin infiltration depths as large as 600 to 2,000 µm were achieved, in contrast to ~10 µm resulting from diffusion/capillarity. Incubation with demineralization solution for 192 h resulted in significant demineralization at noninfiltrated histologic points but not at resin infiltrated. These results open new avenues for the transport of materials in dental enamel. PMID:25691072

  12. A new generalization of the standard electrokinetic model.

    PubMed

    López-García, J J; Grosse, C; Horno, J

    2007-08-01

    We present a new generalization of the standard electrokinetic model based on the assumption that there is a thin layer surrounding the suspended particle where the equilibrium ion density is not determined by the Gouy-Chapman distribution, while the standard model applies outside this layer. Our approach differs from existing models in that we consider that the surface layer is made both of free ions (mostly counterions) and of the fixed ions that constitute the charge of the particle. Furthermore, the free ion density is determined by appropriate boundary conditions without considering any adsorption isotherms. Finally, the fluid is allowed to freely flow inside the layer, only hindered by the presence of the fixed charges and the adhesion condition on the surface of the particle. We show that this generalization leads to results that qualitatively differ from those obtained using existing models: instead of always decreasing, the electrophoretic mobility can actually increase with the anomalous surface conductivity. This could make it possible to use our model for the interpretation of a broader set of experimental data, including those cases when the measured mobility is higher than predicted by the standard model. PMID:17602518

  13. Electrokinetic properties of soil minerals and soils modified with polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Kurochkina, G. N.; Pinskii, D. L.; Haynos, M.; Sokolowska, Z.; Tsesla, I.

    2014-07-01

    The formation features of nanoadsorption polyelectrolyte (PE) layers with the formation of a mineral-organic matrix on the surface of clay minerals and soils (kaolinite, montmorillonite, quartz sand, gray forest soil, and chernozemic soil) have been elucidated by direct adsorption measurements. It has been found that the experimental values for the limit adsorption of polyacrylamide (PAM) and polyacrylic acid (PAA) on all the minerals are significantly higher than the calculated values for the formation of a monolayer. This indicates adsorption on the surface of not only separate macromolecules but also secondary PE structures as packets or fibrils determining the cluster-matrix structure of the modified surface. The study of the electro-surface properties (electrophoretic mobility, electrokinetic potential, pH, and electroconductivity) of mineral and soil particles adsorption-modified with PEs has confirmed the differences in the adsorption mechanisms (from physical sorption to chemisorption) with the formation of surface compounds depending on the different polar groups of PEs and the mineral type.

  14. AC electrokinetic manipulation of selenium nanoparticles for potential nanosensor applications

    SciTech Connect

    Mahmoodi, Seyed Reza; Bayati, Marzieh; Hosseinirad, Somayeh; Foroumadi, Alireza; Gilani, Kambiz; Rezayat, Seyed Mahdi

    2013-03-15

    Highlights: ? Se nanoparticles were synthesized using a reverse-microemulsion process. ? AC osmotic fluid flow repulses the particles from electrode edges. ? Dielectrophoretic force attracts the particles to electrode edges. ? Dielectrophoresis electrode showed non-ohmic behavior. ? The device can potentially be used as a nanosensor. - Abstract: We report the AC electrokinetic behavior of selenium (Se) nanoparticles for electrical characterization and possible application as micro/nano devices. selenium Se nanoparticles were successfully synthesized using a reverse-microemulsion process and investigated structurally using X-ray diffraction and transmission electron microscope. Interdigitated castellated ITO and non-castellated platinum electrodes were employed for manipulation of suspended materials in the fluid. Using ITO electrodes at low frequency limits resulted in deposition of Se particles on electrode surface. When Se particles exposed to platinum electrodes in the 10 Hz–1 kHz range and V {sub p?p}> 8, AC osmotic fluid flow repulses the particles from electrode edges. However, in 10 kHz–10 MHz range and V {sub p?p}> 5, dielectrophoretic force attracts the particles to electrode edges. As the Se particle concentration increased, the trapped Se particles were aligned along the electric field line and bridged the electrode gap. The device was characterized and can potentially be useful in making micro/nano electronic devices.

  15. Synthesis and carbonic anhydrase isoenzymes I, II, IX, and XII inhibitory effects of dimethoxybromophenol derivatives incorporating cyclopropane moieties.

    PubMed

    Bozta?, Murat; Çetinkaya, Yasin; Topal, Meryem; Gülçin, ?lhami; Menzek, Abdullah; ?ahin, Ertan; Tanc, Muhammet; Supuran, Claudiu T

    2015-01-22

    Cyclopropylcarboxylic acids and esters and cyclopropylmethanols incorporating bromophenol moieties were investigated as inhibitors of the carbonic anhydrase enzyme (CA; EC 4.2.1.1). The cis- and trans-esters 5 and 6 were obtained from the reaction of 4-allyl-1,2-dimethoxybenzene (4) with ethyl diazoacetate, which after bromination with Br2 gave two isomeric monobromides (11 and 15), four isomeric dibromides (12, 13, 16, and 17), and two isomeric tribromides (14 and 18). The carboxylic acids 7, 8, and 19-26 were thereafter obtained by hydrolysis of the synthesized esters. All these bromophenol derivatives were tested against human (h) CA isoenzymes I and II (cytosolic, ubiquitous isoforms) and hCA IX and XII (transmembrane, tumor-associated enzymes). All tested bromophenols exhibited excellent inhibitory effects, in the low nanomolar range, with Ki values in the range of 0.54-59 nM against hCA I and in the range of 0.97-12.14 nM against hCA II, whereas they were low micromolar inhibitors against hCA IX and XII. The best hCA I inhibition was observed in new bromophenol derivative 20 (Ki = 0.54 nM). On the other hand, new bromophenol derivative 12 showed a powerful inhibition effect against hCA II (Ki = 0.97 nM). PMID:25432060

  16. On benchmark problems, challenges, and competitions in electrokinetics-A review.

    PubMed

    Hurák, Zden?k; Foret, František

    2015-07-01

    In this critical review, we comment on the absence of widely shared benchmark problems and relevant challenges or even attractive competitions in the field of electrokinetics. We argue that in some other scientific domains that are, similarly as electrokinetics, strongly multidisciplinary, the existence of these tools is very beneficial because it stimulates the discussion about what constitutes the bottleneck of further progress, allows easier exploitation of results provided by other scientific and engineering disciplines, and, last but not least, makes the research domain attractive and visible to a broader public, including students. The goal of this review is to provoke some discussion that might perhaps lead to compensating for these shortcomings. PMID:25820420

  17. Experimental and numerical evidences of the observation of the Biot slow wave thanks to its electrokinetic conversion

    NASA Astrophysics Data System (ADS)

    Bordes, C.; Garambois, S.; Brito, D.; Dietrich, M.; Holzhauer, J.

    2013-12-01

    As originally described by Biot in 1956, seismic propagation in fluid-filled porous media should include two longitudinal contributions: the fast and slow P waves, the latest being commonly referred to as the ';Biot slow wave'. This seismic wave has been seldom observed in natural rocks at laboratory frequencies due to its low amplitude properties and has never been recognized at seismic frequencies due to its diffusive properties. In porous media, a part of seismic energy may also be converted into electromagnetic fields by a coupling phenomenon of electrokinetic nature: the so-called seismoelectric effect. Most seismoelectric studies focus on the observation of co-seismic or depth-converted electric fields generated by the propagation of fast P-waves, mainly to detect or to image new physico-chemical contrasts. Based on Pride's theory (1994), numerical modeling of seismo-electromagnetic wave propagation suggests that the observation of the Biot slow wave could be boosted by its electrokinetic conversion, i.e. that it would be easier to record the electric fields accompanying Biot slow waves generated by a mechanical source rather than the seismic fields. In order to confirm these numerical predictions, we designed a specific laboratory experiment involving a silica sand tank excited by using a homemade pneumatic seismic source. The investigated frequency range [0.5-5kHz] contains the Biot (transition) frequency separating the diffusive from the propagation regimes of the slow wave. Numerical seismoelectromagnetic experiments were also performed at this scale to compute the seismoelectric response in homogeneous and partially saturated sand with this acquisition configuration. The comparison of these experimental data to numerical results provides new perspectives for the detection, study and potential use of the Biot slow wave.

  18. The effect of nitrogen incorporation in Ge-In-Ga-O semiconductor and the associated thin film transistors

    NASA Astrophysics Data System (ADS)

    Ahn, Byung Du; Lee, Kwang Ho; Park, Jozeph; Park, Jin-Seong

    2015-11-01

    The effect of nitrogen doping in Ge-In-Ga-O (GIGO) semiconductors was investigated via thin film characterization and the evaluation of the associated thin film transistor (TFT) properties. As the nitrogen content [N2/(Ar + O2 + N2)] increases from 0% to 40% during the sputter deposition, the threshold voltage (Vth) of the corresponding TFT devices shifts toward positive values (from -1.88 to 3.08 V) and the subthreshold swing decreases (from 0.40 to 0.18 V/decade) accordingly, while the amount of Vth shift (?Vth) by hysteresis is suppressed (from 1.33 to 0.22 V). In particular, the device stability under negative gate bias (-20 V) stress for 3 h improves considerably with total threshold voltage shift (?Vth) values of -6.25 V and -0.69 V. As the amount of nitrogen incorporated in the semiconductor increase, the device ?FE decreases significantly (from 19.3 to 5.76 cm2/V s). Temperature dependent analyses suggest that Coulombic scattering of the carriers near the nitrogen species is the major mechanism of such mobility degradation.

  19. The effect of incorporating RGD adhesive peptide in polyethylene glycol diacrylate hydrogel on osteogenesis of bone marrow stromal cells.

    PubMed

    Yang, Fan; Williams, Christopher G; Wang, Dong-An; Lee, Hyukjin; Manson, Paul N; Elisseeff, Jennifer

    2005-10-01

    Advances in tissue engineering require biofunctional scaffolds that can not only provide cells with structural support, but also interact with cells in a biological manner. To achieve this goal, a frequently used cell adhesion peptide Arg-Gly-Asp (RGD) was covalently incorporated into poly(ethylene glycol) diacrylate (PEODA) hydrogel and its dosage effect (0.025, 1.25 and 2.5 mm) on osteogenesis of marrow stromal cells in a three-dimensional environment was examined. Expression of bone-related markers, osteocalcin (OCN) and Alkaline phosphatase (ALP), increased significantly as the RGD concentration increased. Compared with no RGD, 2.5 mm RGD group showed a 1344% increase in ALP production and a 277% increase in OCN accumulation in the medium. RGD helped MSCs maintain cbfa-1 expression when shifted from a two-dimensional environment to a three-dimensional environment. Soluble RGD was found to completely block the mineralization of marrow stromal cells, as manifested by quantitative calcium assay, phosphorus elemental analysis and Von Kossa staining. In conclusion, we have demonstrated that RGD-conjugated PEODA hydrogel promotes the osteogenesis of MSCs in a dosage-dependent manner, with 2.5 mm being optimal concentration. PMID:15878198

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

    SciTech Connect

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

    2013-12-28

    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 T{sub C} and the effective Mn content x{sub eff} with increasing Sb content. The incorporation of low Sb content is of benefit to increasing x{sub eff}, thus, increasing T{sub C}. However, higher Sb content degrades the crystal quality, resulting in a decrease of x{sub eff}. Experimental results show that T{sub C} is proportional to the product of x{sub eff} and p{sup 1/3}, which is consistent with the Zener Model. The exchange energy N{sub 0}? is calculated to be ?1.09 eV, which is similar to that of (Ga, Mn)As.

  1. Binary electrokinetic separation of target DNA from background DNA primers.

    SciTech Connect

    James, Conrad D.; Derzon, Mark Steven

    2005-10-01

    This report contains the summary of LDRD project 91312, titled ''Binary Electrokinetic Separation of Target DNA from Background DNA Primers''. This work is the first product of a collaboration with Columbia University and the Northeast BioDefense Center of Excellence. In conjunction with Ian Lipkin's lab, we are developing a technique to reduce false positive events, due to the detection of unhybridized reporter molecules, in a sensitive and multiplexed detection scheme for nucleic acids developed by the Lipkin lab. This is the most significant problem in the operation of their capability. As they are developing the tools for rapidly detecting the entire panel of hemorrhagic fevers this technology will immediately serve an important national need. The goal of this work was to attempt to separate nucleic acid from a preprocessed sample. We demonstrated the preconcentration of kilobase-pair length double-stranded DNA targets, and observed little preconcentration of 60 base-pair length single-stranded DNA probes. These objectives were accomplished in microdevice formats that are compatible with larger detection systems for sample pre-processing. Combined with Columbia's expertise, this technology would enable a unique, fast, and potentially compact method for detecting/identifying genetically-modified organisms and multiplexed rapid nucleic acid identification. Another competing approach is the DARPA funded IRIS Pharmaceutical TIGER platform which requires many hours for operation, and an 800k$ piece of equipment that fills a room. The Columbia/SNL system could provide a result in 30 minutes, at the cost of a few thousand dollars for the platform, and would be the size of a shoebox or smaller.

  2. Simulation-based design of a strained graphene field effect transistor incorporating the pseudo magnetic field effect

    SciTech Connect

    Souma, Satofumi Ueyama, Masayuki; Ogawa, Matsuto

    2014-05-26

    We present a numerical study on the performance of strained graphene-based field-effect transistors. A local strain less than 10% is applied over a central channel region of the graphene to induce the shift of the Dirac point in the channel region along the transverse momentum direction. The left and the right unstrained graphene regions are doped to be either n-type or p-type. By using the atomistic tight-binding model and a Green's function method, we predict that the gate voltage applied to the central strained graphene region can switch the drain current on and off with an on/off ratio of more than six orders of magnitude at room temperature. This is in spite of the absence of a bandgap in the strained channel region. Steeper subthreshold slopes below 60?mV/decade are also predicted at room temperature because of a mechanism similar to the band-to-band tunneling field-effect transistors.

  3. Rapid analysis of caffeine in ``smart drugs'' and ``energy drinks'' by microemulsion electrokinetic chromatography (MEEKC)

    E-print Network

    Miksik, Ivan

    chromatography (MEEKC) Eloisa Liotta a , Rossella Gottardo a , Catia Seri b , Claudia Rimondo b , Ivan Miksik c: gas chromatography­mass spectrometry (GC­MS) [10,11] and HPLC­MS [12,13]. Unfortunately Keywords: Caffeine Energy drink Smart drug Microemulsion electrokinetic chromatography A B S T R A C

  4. Concentration Polarization and Nonlinear Electrokinetic Flow near a Nanofluidic Channel Sung Jae Kim,1

    E-print Network

    Concentration Polarization and Nonlinear Electrokinetic Flow near a Nanofluidic Channel Sung Jae within nanofluidic channels, with critical dimensions of 10­100 nm, have drawn a lot of attention,3], nanofluidic channels can be an ideal, well-controlled experimental platform to study nanoscale molecular

  5. 42 CFR 137.48 - What is the effect of incorporating a Title I provision into a compact or funding agreement?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...incorporating a Title I provision into a compact or funding agreement? 137.48 Section 137.48 Public...AND HUMAN SERVICES TRIBAL SELF-GOVERNANCE Funding Agreements Terms in A Funding Agreement § 137.48 What is the effect...

  6. Electrokinetically enhanced flow and dewatering characteristics of concentrated black coal-water suspensions in pipes

    SciTech Connect

    Rozakeas, P.K.; Snow, R.J.

    1997-07-01

    The transportability and dewatering of coal-water mixtures flowing in a pipe may be enhanced by the application of electrokinetic techniques. Previous experimental work by other workers shows a significant reduction in the wall shear stress, and consequently a decrease in pumping energy requirements for the flow of coal-water mixtures in pipes combined with electrodewatering. In this process the pipe wall acts as the cathode and a centrally aligned tube as the anode. The effects of {open_quote}In-pipe electrodewatering{close_quote} on the flow properties and stability of concentrated coal-water mixtures flowing in various alternative anode-cathode arrangements are presented in this paper. The application of an electrical energy flux at the electrode surface (< 6.1 kW/m{sup 2}) in a dewatering section of pipe (L{sub e}=1m) effectively reduces the pumping energy requirements by as much as one order of magnitude. The stability of flow conditions is investigated in a concentric anode-cathode pipe arrangement consisting of a dewatering and a non-dewatering section (L{sub o}). In this system (L{sub o}/L{sub e}) < 4.0. A microscopic study of dilute coal-water suspensions in the presence of a DC electric field revealed the migration of coal particles towards the anode and the structural formation of coal particle chains. The electrorheological behaviour of concentrated coal-water suspensions is examined with the use of a modified coaxial rheometer. The coal fines (d{sub 50}=17.7{mu}m) used in all experiments were produced by milling a low rank bituminous black coal which was followed by a sieving process that eliminated coal particles that were greater than 75{mu}m in size.

  7. Geochemical characterization and heavy metal migration in a coastal polluted aquifer incorporating tidal effects: field investigation in Chongming Island, China.

    PubMed

    Liu, Shuguang; Tan, Bo; Dai, Chaomeng; Lou, Sha; Tao, An; Zhong, Guihui

    2015-12-01

    The occurrence and migration of heavy metal in coastal aquifer incorporating tidal effects were investigated in detail by the field geological survey and observation. The continuous groundwater sampling, field observation (for groundwater potentiometric surface elevation, pH, dissolved oxygen, temperature, and salinity), and laboratory analysis (for Cr, Ni, Cu, Zn, Cd, and Pb concentration) were conducted through eight monitoring wells located around the landfill in the northern part of Chongming Island, China. The results showed that the unconfined aquifer medium was estuary-littoral facies deposit of Holocene, mainly gray clayey silt and grey sandy silt, and the groundwater flow was mainly controlled by topography condition of the aquifer formation strike. The background values of Cr, Ni, Cu, Zn, Cd, and Pb in Chongming Island were 3.10?±?3.09, 0.81?±?0.25, 1.48?±?1.09, 43.32?±?33.06, 0.08?±?0.16, and 0.88?±?1.74 ?g/L, respectively. Compared with the groundwater samples around the study area, the drinking water was qualified and was free from the seawater intrusion/estuarine facies contaminant encroachment. Pollutant discharge was reflected in water quality parameters, the Cr and Cu concentrations elevated to the peak of 50.07 and 46.00 ?g/L, respectively, and meanwhile specific migration regularity was embodied in observation time series as well as other elements. This migration regularity was not fully identical according to correlations between these analyzed elements. Ambient watery environment, anthropogenic disturbance, regional hydrogeological condition, and biogeochemical reactivity on heavy metals reduced/altered the significance of elements correlation in the migration pathway in coastal aquifer. PMID:26300351

  8. Effect of dietary adherence on the body weight plateau: a mathematical model incorporating intermittent compliance with energy intake prescription123

    PubMed Central

    Thomas, Diana M; Martin, Corby K; Redman, Leanne M; Heymsfield, Steven B; Lettieri, Steven; Levine, James A; Bouchard, Claude; Schoeller, Dale A

    2014-01-01

    Background: Clinical weight loss in individuals typically stabilizes at 6 mo. However, validated models of dynamic energy balance have consistently shown weight plateaus between 1 and 2 y. The cause for this discrepancy is unclear. Objective: We developed 2 mathematical models on the basis of the first law of thermodynamics to investigate plausible explanations for reaching an early weight plateau at 6 mo. Design: The first model was an energy-expenditure adaptation model and was applied to determine the degree of metabolic adaptation required to generate this plateau. The second model was an intermittent lack-of-adherence model formulated by using a randomly fluctuating energy intake term accounting for intermittent noncompliance in dietary intake to reach this plateau. To set model variables, validate models, and compare free-living weight-loss patterns to in-residence supervised programs, we applied the following 4 different studies: The US NHANES 1999–2004, Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) weight-loss study, the Bouchard Twin overfeeding study, and the Minnesota Starvation Experiment. Results: The metabolic adaptation model increased final weight but did not affect the predicted plateau time point. The intermittent lack-of-adherence model generated oscillating weight graphs that have been frequently observed in weight-loss studies. The model showed that a 6-mo weight-loss plateau can be attained despite what can be considered as high diet adherence. The model was programmed as a downloadable application. Conclusions: An intermittent lack of diet adherence, not metabolic adaptation, is a major contributor to the frequently observed early weight-loss plateau. The new weight-loss prediction software, which incorporates an intermittent lack of adherence, can be used to guide and inform patients on realistic levels of adherence on the basis of patient lifestyle. The CALERIE study was registered at clinicaltrials.gov as NCT00099151. PMID:25080458

  9. Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity

    USGS Publications Warehouse

    Frankel, Arthur D.; Stephenson, William J.; Carver, David L.; Williams, Robert A.; Odum, Jack K.; Rhea, Susan

    2007-01-01

    This report presents probabilistic seismic hazard maps for Seattle, Washington, based on over 500 3D simulations of ground motions from scenario earthquakes. These maps include 3D sedimentary basin effects and rupture directivity. Nonlinear site response for soft-soil sites of fill and alluvium was also applied in the maps. The report describes the methodology for incorporating source and site dependent amplification factors into a probabilistic seismic hazard calculation. 3D simulations were conducted for the various earthquake sources that can affect Seattle: Seattle fault zone, Cascadia subduction zone, South Whidbey Island fault, and background shallow and deep earthquakes. The maps presented in this document used essentially the same set of faults and distributed-earthquake sources as in the 2002 national seismic hazard maps. The 3D velocity model utilized in the simulations was validated by modeling the amplitudes and waveforms of observed seismograms from five earthquakes in the region, including the 2001 M6.8 Nisqually earthquake. The probabilistic seismic hazard maps presented here depict 1 Hz response spectral accelerations with 10%, 5%, and 2% probabilities of exceedance in 50 years. The maps are based on determinations of seismic hazard for 7236 sites with a spacing of 280 m. The maps show that the most hazardous locations for this frequency band (around 1 Hz) are soft-soil sites (fill and alluvium) within the Seattle basin and along the inferred trace of the frontal fault of the Seattle fault zone. The next highest hazard is typically found for soft-soil sites in the Duwamish Valley south of the Seattle basin. In general, stiff-soil sites in the Seattle basin exhibit higher hazard than stiff-soil sites outside the basin. Sites with shallow bedrock outside the Seattle basin have the lowest estimated hazard for this frequency band.

  10. Polymer adsorption and electrokinetic potential of dispersed particles in weak and strong electric fields.

    PubMed

    Barany, Sandor

    2015-08-01

    A review on the effects of adsorbed non-ionic polymers and polyelectrolytes on the electrophoresis of dispersed particles is given. The variety of changes in the electrical double layer (EDL) structure and, in particular, electrokinetic potential in weak electric fields as a result of polymer adsorption is discussed. Examples on the dependence of zeta potential of particles on the adsorbed amount of polymers are described. An analysis of the influence of various complicating factors, namely polarization of the EDL, curvature of the surface and the presence of electrolytes, on the calculation of polymer layer thickness from electrophoretic data has been performed. Results of electrophoretic measurements in suspensions of non-conventional particles (TiC, SiC and Si3N4) having adsorbed polyethylene oxide are presented. Regularities of the effect of anionic and cationic polyelectrolytes (PEs) and their binary mixtures on the electrokinetic potential of dispersed particles (polystyrene, silica, bentonite and kaolin) as a function of the polymer dose, pH, charge density (CD) of the polyelectrolyte, as well as the mixture composition and the sequence of component addition are described. It has been shown that addition of increasing amount of anionic PEs increases the absolute value of the negative zeta potential of particles, while adsorption of cationic PEs results in a significant decrease in the negative ?-potential and overcharging the particle surface; changes in the ?-potential are more pronounced for samples with higher CD. In mixtures of cationic and anionic PEs, in a wide range of their composition, the ?-potential of negatively charged particles is determined by the adsorbed amount of the anionic polymer independently of the CD of polyelectrolyte and the sequence of the mixture component addition. The role of coulombic and non-coulombic forces in the mechanism of polyelectrolyte adsorption and structure of adsorbed layers formed is discussed. The results of comparative investigations on the effect of adsorbed polymers on the electrophoresis of dispersed particles in weak and strong electric fields are presented. It is shown that adsorption of non-ionic polymers only slightly (by about 20-50%) decreases the electrophoretic velocity (V(ef)) of polystyrene, graphite and aluminium-oxide particles in strong fields (100-400 V/cm). This is in contrast to the electrophoresis in weak fields (5-20 V/cm) in which adsorption of these polymers gives a drop in V(ef) by an order of magnitude or even more. In line with our theoretical predictions, it means that the non-linear ("cubic") electrophoresis, that arises in strong electric fields, is independent of the position of the shear plane, i.e. the zeta potential value. It is determined mainly by the surface conductivity of particles, i.e. by the Dukhin number that characterizes the polarization of the electric double layer. PMID:25456453

  11. Dose and time dependent effects of morphine on the incorporation of (3H)valine into soluble brain and liver proteins

    SciTech Connect

    Roennbaeck, L.; Hansson, E.; Cupello, A.

    1983-03-01

    Morphine (10(-6)-10(-5) M) causes an increase in incorporation of (/sup 3/H)valine into soluble proteins during 4 hr in rat brain cortical slices, liver slices and cultivated astroglial cells. The effects are dose-dependent. They are neither cell specific nor strictly related to classical opiate receptors. Pulse-labeling with (/sup 3/H)valine for 60 min after incubation in 10(-6)-10(-5) M morphine, resolves time-dependent changes in incorporation, with both increases and decreases in protein metabolism.

  12. Fluid flow monitoring in oilfields using downhole measurements of electrokinetic potential

    NASA Astrophysics Data System (ADS)

    Jackson, M. D.; Saunders, J. H.; Pain, C. C.

    2006-12-01

    Permanently installed downhole sensors are increasingly being deployed to provide `real-time' reservoir data during hydrocarbon production, which helps to reduce uncertainty in the reservoir description and contributes to reservoir management decisions. Where wells are equipped with inflow control valves (so called `intelligent' wells), it is possible to develop a feedback loop between measurement and control to optimize production. We suggest that measurements of electrokinetic potential during production, using permanently installed downhole electrodes, could be used to detect water encroachment towards an intelligent oil well. Downhole electrodes mounted at the production well on the outside of insulated casing, have been successfully applied in subsurface resistivity surveys during oil production. Similar technology could be used to measure electrokinetic potential. Moreover, recent and ongoing work has changed our understanding of electrokinetic coupling under two-phase conditions. We present the results of numerical simulations of fluid movement during hydrocarbon production, using a new formulation which captures both the changing fluid distributions and the resulting electrical potentials. We suggest that encroaching water causes changes in electrokinetic potential at the production well which could be resolved above background electrical noise; indeed, changes in water saturation could be detected several 10's to 100's of metres away from the well. This contrasts with most other downhole monitoring techniques, which sample only the region immediately adjacent to the wellbore. Signal resolution is improved if the water has a relatively low salinity, and the pressure gradient into the well is large. However, significant uncertainties remain concerning the nature of electrokinetic coupling during the flow of oil and water, particularly in mixed and oil-wet reservoirs.

  13. Incorporating Climate Change Effects into Next-Generation Coastal Inundation Decision Support Systems: An Integrated and Community-Based Approach

    NASA Astrophysics Data System (ADS)

    Sheng, Y.; Davis, J. R.; Paramygin, V. A.; LaRow, T.; Chassignet, E.; Stefanova, L. B.; Lu, J.; Xie, L.; Montalvo, S.; Liu, J.; Liu, B.

    2012-12-01

    75% of the world population lives within 100 km from the coastline. Coastal communities are subject to increasing coastal inundation risk due to the combined effects of hurricane-induced storm surge, tsunami, climate change, and sea level rise. This study is developing the next generation decision support systems (DSS) for storm surge and coastal inundation by incorporating the climate change impacts on hurricanes and sea level rise (SLR) along the Florida and North Carolina coast. Using a new methodology (instead of the "bath tub" approach) enhanced by the Institute for Sustainable Coastal Environment and Infrastructure (InSCEI) at University of Florida (UF), highly accurate and efficient coastal inundation maps (Base Flood Elevations and Surge Atlas) are being produced for current climate conditions. Atmospheric and climate scientists at Florida State University (FSU) and North Carolina State University (NCSU) are using global (FSU/COAPS) and regional (WRF) atmospheric models to estimate the range in hurricane activities during 2020-2040 and 2080-2100, using projected SSTs from the IPCC CMIP5 climate scenarios as lower boundary conditions. SLR experts at NCSU and FSU are analyzing historical sea level data and conducting numerical modeling to estimate the SLR at the coastal boundaries for the same IPCC scenarios. UF and NCSU are using the hurricane ensembles and the SLR scenarios provided by FSU and NCSU as input to storm surge and inundation models (CH3D-SSMS and CMAEPS, respectively) to produce high resolution inundation maps which include climate change effects. These future-climate coastal inundation maps will be much more accurate than the current ones and greatly improve the stakeholders' ability to mitigate coastal inundation risk throughout the U.S. and the world. These inundation maps for current and future climates will be communicated to a wide spectrum of stakeholders for feedback and further improvement. A national workshop will be held in January 2013 to engage stakeholders, researchers, and managers (federal, state, and local) of coastal inundation to develop strategies to improve communications among the various entities and to gather inputs on the development of the next -generation coastal inundation decision support system.

  14. TRACE ANALYSIS OF FLUORESCEIN-DERIVATIZED PHENOXY ACID HERBICIDES BY MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH LASER-INDUCTED FLUORESCENCE DETECTION

    EPA Science Inventory

    Micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence (LIF) detection was used for the trace analysis of phenoxy acid herbicides. Capillary electrophoresis (CE) with LIF detection, which has not previously been used for pesticide analysis, overcomes the po...

  15. Bench-scale electrokinetic remediation for cesium-contaminated sediment at the Hanford Site, USA

    SciTech Connect

    Jung, Hun Bok; Yang, Jungseok; Um, Wooyong

    2015-05-01

    Electrokinetic (EK) remediation has been applied to extract various contaminants such as radionuclides, heavy metals, and organic compounds from contaminated sediment and soil using electric currents. We conducted a laboratory experiment to investigate the efficiency of EK remediation method for Hanford sediment (76% sand and 24% silt-clay) after artificial contamination with nonradioactive 133Cs (0.01 M CsNO3) as a surrogate for radioactive 137Cs. The initial 133Cs concentration in the bulk sediment was 668 mg kg-1, with a higher 133Cs concentration for the silt-clay fraction (867 mg kg-1) than for the sand fraction (83 mg kg-1). A significant removal of cationic 133Cs from the sediment occurred from the cathode side (-), whereas the removal was negligible from the anode side (+) during the EK remediation process for 68 days. Based on microwave-assisted total digestion, 312 mg kg-1 of 133Cs was removed from the bulk sediment, which corresponds to the removal efficiency of 47%. The EK method was significantly more efficient for the silt-clay fraction than for the sand fraction. X-ray diffraction (XRD) and scanning electron microscopy-electron dispersive spectroscopy (SEM-EDS) analyses indicate that change in major crystalline mineral phases was insignificant during the EK remediation and the removal of 133Cs from the Hanford sediment by the EK method is attributed mainly to cation exchange with K in clay minerals. The experimental results suggest that the EK method can effectively remove radioactive Cs from the surface or subsurface sediment contaminated by radioactive materials in the Hanford Site, Washington, USA.

  16. Evaluation of newly synthesized and commercially available charged cyclomaltooligosaccharides (cyclodextrins) for capillary electrokinetic chromatography.

    PubMed

    Culha, Mustafa; Schell, Fred M; Fox, Shannon; Green, Thomas; Betts, Thomas; Sepaniak, Michael J

    2004-01-22

    A highly new charged cyclodextrin (CD) derivatives, (6-O-carboxymethyl-2,3-di-O-methyl)cyclomaltoheptaoses (CDM-beta-CDs), was synthesized and characterized as anionic reagents for capillary electrophoresis (CE) in an electrokinetic chromatography mode of separation. Substitution with dimethyl groups at the secondary hydroxyl sites of the CD is aimed at influencing the magnitude and selectivity of analyte-CD interactions, while substitution by carboxymethyl groups at the primary hydroxyl sites provides for high charge and electrophoretic mobility. Full regioselective methylation at the secondary hydroxyl sites was achieved in this work, while substitution at the primary hydroxyl sites generated a mixture of multiply charged products. The separation performance of CDM-beta-CD was evaluated using a variety of analyte mixtures. The results obtained from commercially available negatively charged cyclodextrins, heptakis(2,3-di-O-methyl-6-O-sulfo)cyclomaltoheptaose (HDMS-beta-CD) and O-(carboxymethyl)cyclomaltoheptaose (CM-beta-CD) with an average degree of substitution one (DS 1), were compared to CDM-beta-CD using a sample composed of eight positional isomers of dihydroxynaphthalene. Four hydroxylated polychlorobiphenyl derivatives, a group of chiral and isomeric catchecins, and chiral binaphthyl compounds were also separated with CDM-beta-CD. The effect of adding neutral beta-cyclodextrin (beta-CD) into the running buffer containing charged cyclodextrins was investigated and provided evidence of significant inter-CD interactions. Under certain running buffer conditions, the charged cyclodextrins also appear to adsorb to the capillary walls to various degrees. PMID:14698882

  17. Effect of liquid swine manure rate, incorporation, and timing of rainfall on phosphorus loss with surface runoff

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excessive manure P application increases risk of P loss from fields. This study assessed total (TPR), bioavailable (BAP), and dissolved reactive (DRP) P concentrations and loads in surface runoff following liquid swine (Sus scrofa domesticus) manure application with or without incorporation into soi...

  18. Assessment of electrokinetic removal of heavy metals from soils by sequential extraction analysis.

    PubMed

    Reddy, K R; Xu, C Y; Chinthamreddy, S

    2001-06-29

    Electrokinetic remediation of metal-contaminated soils is strongly affected by soil-type and chemical species of contaminants. This paper investigates the speciation and extent of migration of heavy metals in soils during electrokinetic remediation. Laboratory electrokinetic experiments were conducted using two diverse soils, kaolin and glacial till, contaminated with chromium as either Cr(III) or Cr(VI). Initial total chromium concentrations were maintained at 1000mg/kg. In addition, Ni(II) and Cd(II) were used in concentrations of 500 and 250mg/kg, respectively. The contaminated soils were subjected to a voltage gradient of 1 VDC/cm for over 200h. The extent of migration of contaminants after the electric potential application was determined. Sequential extractions were performed on the contaminated soils before and after electrokinetic treatment to provide an understanding of the distribution of the contaminants in the soils. The initial speciation of contaminants was found to depend on the soil composition as well as the type and amounts of different contaminants present. When the initial form of chromium was Cr(III), exchangeable and soluble fractions of Cr, Ni, and Cd ranged from 10 to 65% in kaolin; however, these fractions ranged from 0 to 4% in glacial till. When the initial form of chromium was Cr(VI), the exchangeable and soluble fractions of Cr, Ni and Cd ranged from 66 to 80% in kaolin. In glacial till, however, the exchangeable and soluble fraction for Cr was 38% and Ni and Cd fractions were 2 and 10%, respectively. The remainder of the contaminants existed as the complex and precipitate fractions. During electrokinetic remediation, Cr(VI) migrated towards the anode, whereas Cr(III), Ni(II) and Cd(II) migrated towards the cathode. The speciation of contaminants after electrokinetic treatment showed that significant change in exchangeable and soluble fractions occurred. In kaolin, exchangeable and soluble Cr(III), Ni(II), and Cd(II) decreased near the anode and increased near the cathode, whereas exchangeable and soluble Cr(VI) decreased near the cathode and increased near the anode. In glacial till, exchangeable and soluble Cr(III), Ni(II), and Cd(II) were low even before electrokinetic treatment and no significant changes were observed after the electrokinetic treatment. However, significant exchangeable and soluble Cr(VI) that was present in glacial till prior to electrokinetic treatment decreased to non-detectable levels near the cathode and increased significantly near the anode. In both kaolin and glacial till, low migration rates occurred as a result of contaminants existing as immobile complexes and precipitates. The overall contaminant removal efficiency was very low (less than 20%) in all tests. PMID:11406312

  19. Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kim, Jeomoh; Ji, Mi-Hee; Detchprohm, Theeradetch; Dupuis, Russell D.; Fischer, Alec M.; Ponce, Fernando A.; Ryou, Jae-Hyun

    2015-09-01

    Unintentional incorporation of gallium (Ga) in InAlN layers grown with different molar flow rates of Group-III precursors by metalorganic chemical vapor deposition has been experimentally investigated. The Ga mole fraction in the InAl(Ga)N layer was increased significantly with the trimethylindium (TMIn) flow rate, while the trimethylaluminum flow rate controls the Al mole fraction. The evaporation of metallic Ga from the liquid phase eutectic system between the pyrolized In from injected TMIn and pre-deposited metallic Ga was responsible for the Ga auto-incorporation into the InAl(Ga)N layer. The theoretical calculation on the equilibrium vapor pressure of liquid phase Ga and the effective partial pressure of Group-III precursors based on growth parameters used in this study confirms the influence of Group-III precursors on Ga auto-incorporation. More Ga atoms can be evaporated from the liquid phase Ga on the surrounding surfaces in the growth chamber and then significant Ga auto-incorporation can occur due to the high equilibrium vapor pressure of Ga comparable to effective partial pressure of input Group-III precursors during the growth of InAl(Ga)N layer.

  20. A three-scale model for ionic solute transport in swelling clays incorporating ion-ion correlation effects

    NASA Astrophysics Data System (ADS)

    Le, Tien Dung; Moyne, Christian; Murad, Marcio A.

    2015-01-01

    A new three-scale model is proposed to describe the movement of ionic species of different valences in swelling clays characterized by three separate length scales (nano, micro, and macro) and two levels of porosity (nano- and micropores). At the finest (nano) scale the medium is treated as charged clay particles saturated by aqueous electrolyte solution containing monovalent and divalent ions forming the electrical double layer. A new constitutive law is constructed for the disjoining pressure based on the numerical resolution of non-local problem at the nanoscale which, in contrast to the Poisson-Boltzmann theory for point charge ions, is capable of capturing the short-range interactions between the ions due to their finite size. At the intermediate scale (microscale), the two-phase homogenized particle/electrolyte solution system is represented by swollen clay clusters (or aggregates) with the nanoscale disjoining pressure incorporated in a modified form of Terzaghi's effective principle. At the macroscale, the electro-chemical-mechanical couplings within clay clusters is homogenized with the ion transport in the bulk fluid lying in the micro pores. The resultant macroscopic picture is governed by a three-scale model wherein ion transport takes place in the bulk solution strongly coupled with the mechanics of the clay clusters which play the role of sources/sinks of mass to the bulk fluid associated with ion adsorption/desorption in the electrical double layer at the nanoscale. Within the context of the quasi-steady version of the multiscale model, wherein the electrolyte solution in the nanopores is assumed at instantaneous thermodynamic equilibrium with the bulk fluid in the micropores, we build-up numerically the ion-adsorption isotherms along with the constitutive law of the retardation coefficients of monovalent and divalent ions. In addition, the constitutive law for the macroscopic swelling pressure is reconstructed numerically showing patterns of attractive forces between particles for bivalent ions for particular ranges of bulk concentrations. The three-scale model is applied to numerically simulate ion diffusion in a compacted clay liner underneath a sanitary landfill. Owing to the distinct constitutive behavior of the swelling pressure and partition coefficient for each ionic species, different compaction regimes and diffusion/adsorption patterns, with totally different characteristic time scales, are observed for sodium and calcium migration in the clay liner.

  1. Incorporation of vitamin E in poly(3hydroxybutyrate)/Bioglass composite films: effect on surface properties and cell attachment.

    PubMed

    Misra, Superb K; Philip, Sheryl E; Chrzanowski, Wojciech; Nazhat, Showan N; Roy, Ipsita; Knowles, Jonathan C; Salih, Vehid; Boccaccini, Aldo R

    2009-04-01

    This study investigated the possibility of incorporating alpha-tocopherol (vitamin E) into poly(3hydroxybutyrate) (P(3HB))/Bioglass composites, which are being developed for bone tissue engineering matrices. P(3HB) films with 20 wt% Bioglass and 10 wt% vitamin E were prepared using the solvent casting technique. Addition of vitamin E significantly improved the hydrophilicity of the composites along with increasing the total protein adsorption. The presence of protein adsorbed on the composite surface was further confirmed using X-ray photoelectron spectroscopy analysis. Preliminary cell culture studies using MG-63 human osteoblasts showed that the addition of vitamin E in the P(3HB)/20 wt% Bioglass films significantly increased cell proliferation. The results achieved in this study confirmed the possibility of incorporating vitamin E as a suitable additive in P(3HB)/Bioglass composites to engineer the surface of the composites by promoting higher protein adsorption and increasing the hydrophilicity. PMID:18765336

  2. Effects of sodium incorporation in Co-evaporated Cu2ZnSnSe4 thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Li, Jian V.; Kuciauskas, Darius; Young, Matthew R.; Repins, Ingrid L.

    2013-04-01

    Sodium incorporation into Cu2ZnSnSe4 (CZTSe) substantially improves the device efficiency by enhancing the open-circuit voltage (VOC) and fill factor. Sodium increases hole density, makes the acceptor shallower, shifts the Fermi level lower, and leads to higher built-in voltage and, consequently, higher VOC. Sodium reduces the concentration of certain deep recombination centers, which further benefits VOC. The increase of hole density and mobility enhances the CZTSe conductivity leading to higher fill factor. Sodium causes smaller depletion width, hence, lower short-circuit current. The minority-carrier lifetime decreases slightly after sodium is incorporated via the Mo-coated soda-lime glass, although adding NaF provides some amelioration.

  3. Effects of rice residue incorporation on the speciation, potential bioavailability and risk of mercury in a contaminated paddy soil.

    PubMed

    Zhu, Huike; Zhong, Huan; Evans, Douglas; Hintelmann, Holger

    2015-08-15

    To reduce air pollution, straw return instead of burning is being strongly encouraged in China, including some mercury polluted areas. Nevertheless, the possible influences of straw return on methylation, bioavailability and exposure risk of mercury were relatively unknown. In this study, different amounts of rice straw or root were added into a mercury contaminated soil. Potential bioavailability of soil-bound mercury to crops/deposit-feeders was assessed by quantifying extraction rates of mercury (%) by calcium chloride (CaCl2)/bovine serum albumin (BSA). Extraction rates of inorganic mercury (IHg) or methylmercury (MMHg) decreased significantly in rice residue amended soils, possibly due to the strong binding of mercury with organic matter in root/straw. Meanwhile, MMHg concentrations increased by 2-8 times in amended soils. Such increases were attributed to enhanced microbial activities and/or formation of Hg-S-DOM complexes after rice residue incorporation and decomposition. Consequently, potential exposure risk of IHg (quantified as concentration of potentially bioavailable mercury in soil) decreased significantly while that of MMHg increased up to 4 times. To our knowledge, this is the first study demonstrating that rice residue incorporation could significantly affect biogeochemistry of both IHg and MMHg in soils, which should be considered in straw incorporation activities in mercury polluted areas. PMID:25827269

  4. Effect of Substrate Orientation on the Growth Rate, Surface Morphology and Silicon Incorporation on GaSb Grown by Metal-Organic Vapor Phase Epitaxy

    SciTech Connect

    Jian Yu; Ishwara B. Bhat

    2004-01-12

    The growth and dopant incorporation during metal-organic vapor phase epitaxy (MOVPE) strongly depends on the orientation of the starting substrates. MOVPE of Si-doped GaSb layers on (100), (111)B and (111)A substrates were used to investigate the effect of orientation on the growth rate, the surface morphology and the silicon incorporation. orientation dependence of growth rates was studied as a function of temperature and V/III ratio. As the V/III ratios increases, the growth rate on the (111)B oriented substrate decreases, whereas that on the (111)A oriented substrate increases. The surface morphology on different substrates was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Flat-top hexagonal hillocks were observed on (111)B surface, and the growth was by step-flow on these facets. A surface kinetic growth model has been proposed to describe the growth features observed on (111)B surfaces. Finally, the orientation dependence of silicon incorporation was studied by secondary ion mass spectrometry (SIMS) and Hall measurements. It was found that the silicon incorporation rate was four times higher on (100) oriented surface than on (111)B oriented substrates. Although no conduction type switch was found on (111)B oriented substrate, throughout the Si doping range studied, a Ga slightly rich growth condition might be one of the factors accounting for the discrepancy between theoretical prediction and experimental results.

  5. Effect of interface incorporation of cadmium nanocrystallites on the photovoltaic performance of solar cells based on CdS/Si multi-interface nanoheterojunction

    NASA Astrophysics Data System (ADS)

    Li, Yong; Wang, Xiao Bo; Tian, Yong Tao; Li, Xin Jian

    2014-11-01

    A non-planar and multi-interface CdS/Si nanoheterojunction was prepared by growing CdS nanocrystallites (nc-CdS) onto silicon nanoporous pillar array (Si-NPA) using a chemical bath deposition (CBD) method. Utilizing the surface reducibility of Si-NPA, small quantities of Cd nanocrystallites (nc-Cd) were incorporated naturally into the CdS-Si interface during the CBD process. Solar cells with a device construction of ITO/CdS/Si-NPA/Al were prepared based on CdS/Si-NPA and their photovoltaic performances, including open circuit voltage, short circuit current density, external quantum efficiency and energy conversion efficiency, were measured under simulated AM 1.5 G illumination. Compared with CdS/Si-NPA cells without nc-Cd incorporation, an energy conversion efficiency promotion by two orders of magnitude was achieved, which was ascribed to the reduction of the series resistance resulted from the nc-Cd incorporation at the interface. Our results show that the incorporation of nc-Cd at CdS-Si interface might be an effective path for obtaining high-efficiency solar cells based on CdS/Si multi-interface nanoheterojunctions.

  6. An electrokinetic/Fe0 permeable reactive barrier system for the treatment of nitrate-contaminated subsurface soils.

    PubMed

    Suzuki, Tasuma; Oyama, Yukinori; Moribe, Mai; Niinae, Masakazu

    2012-03-01

    Effective nitrate removal by Fe(0) permeable reactive barriers (Fe(0) PRB) has been recognized as a challenging task because the iron corrosion product foamed on Fe(0) hinders effective electron transfer from Fe(0) to surface-bound nitrate. The objectives of this study were (i) to demonstrate the effectiveness of an electrokinetic/Fe(0) PRB system for remediating nitrate-contaminated low permeability soils using a bench-scale system and (ii) to deepen the understanding of the behavior and fate of nitrate in the system. Bench-scale laboratory experiments were designed to investigate the influence of the Fe(0) content in the permeable reactive barrier, the pH in the anode well, and the applied voltage on remediation efficiency. The experimental results showed that the major reaction product of nitrate reduction by Fe(0) was ammonium and that nitrate reduction efficiency was significantly influenced by the variables investigated in this study. Nitrate reduction efficiency was enhanced by either increasing the Fe(0) content in the Fe(0) reactive barrier or decreasing the initial anode pH. However, nitrate reduction efficiency was reduced by increasing the applied voltage from 10 V to 40 V due to the insufficient reaction time during nitrate migration through the Fe(0) PRB. For all experimental conditions, nearly all nitrate nitrogen was recovered in either anode or cathode wells as nitrate or ammonium within 100 h, demonstrating the effectiveness of the system for remediating nitrate-contaminated subsurface soils. PMID:22153957

  7. Electrokinetic secondary-flow behavior in a curved microchannel under dissimilar surface conditions.

    PubMed

    Chun, Myung-Suk

    2011-03-01

    The curved channel appears to be indispensable for the lab-on-chips systems because it provides a convenient scheme for increasing the channel length per unit chip area in the direction of net flow. A secondary Dean flow in curved rectangular microchannels is examined by applying the finite-volume scheme with a semi-implicit method for pressure-linked equations (SIMPLE) algorithm for the pressure-driven electrokinetic transport. This framework is based on the theoretical model coupled with the full Poisson-Boltzmann, Navier-Stokes, and the Nernst-Planck principles of net charge conservation [Yun et al., Phys. Fluids 22, 052004 (2010)]. The effect of a dissimilar wall condition on the secondary flow at the turn is explored by considering different configurations of channel wall having complementary aspect ratios (i.e., ratio of the channel height to the channel width, H/W = 0.25 and 4.0) with combinations of hydrophilic glass and hydrophobic polydimethylsiloxane surfaces. Simulation results exhibit that, contrary to the case of general narrow-bore channels, the streamwise axial velocity tends to shift toward the inner wall caused by a stronger effect of the spanwise pressure gradient, according to a sufficiently low Dean number. The increasing rate of this shift with increasing curvature ratio is more significant in the shallow (or low-aspect-ratio) channel, due to the effect of greater distance traveled by the fluid along the outer wall. The curvature introduces the presence of pairs of counter-rotating vortices perpendicular to the flow direction. Comparing between shallow and deep (or high-aspect-ratio) channels allows us to identify that the patterns of axial velocity and vorticity are altered by the heterogeneity effect of surfaces occupying a large area. The total magnitude of vorticity at the cross section of the channel increases with increasing slip length, due to the contribution of enhanced axial velocity driven by the slip, while there is no fluid-slip dependency for the slip length of less than about 50 nm. PMID:21517592

  8. Electrokinetic secondary-flow behavior in a curved microchannel under dissimilar surface conditions

    NASA Astrophysics Data System (ADS)

    Chun, Myung-Suk

    2011-03-01

    The curved channel appears to be indispensable for the lab-on-chips systems because it provides a convenient scheme for increasing the channel length per unit chip area in the direction of net flow. A secondary Dean flow in curved rectangular microchannels is examined by applying the finite-volume scheme with a semi-implicit method for pressure-linked equations (SIMPLE) algorithm for the pressure-driven electrokinetic transport. This framework is based on the theoretical model coupled with the full Poisson-Boltzmann, Navier-Stokes, and the Nernst-Planck principles of net charge conservation [Yun , Phys. FluidsPFLDAS0031-917110.1063/1.3427572 22, 052004 (2010)]. The effect of a dissimilar wall condition on the secondary flow at the turn is explored by considering different configurations of channel wall having complementary aspect ratios (i.e., ratio of the channel height to the channel width, H/W = 0.25 and 4.0) with combinations of hydrophilic glass and hydrophobic polydimethylsiloxane surfaces. Simulation results exhibit that, contrary to the case of general narrow-bore channels, the streamwise axial velocity tends to shift toward the inner wall caused by a stronger effect of the spanwise pressure gradient, according to a sufficiently low Dean number. The increasing rate of this shift with increasing curvature ratio is more significant in the shallow (or low-aspect-ratio) channel, due to the effect of greater distance traveled by the fluid along the outer wall. The curvature introduces the presence of pairs of counter-rotating vortices perpendicular to the flow direction. Comparing between shallow and deep (or high-aspect-ratio) channels allows us to identify that the patterns of axial velocity and vorticity are altered by the heterogeneity effect of surfaces occupying a large area. The total magnitude of vorticity at the cross section of the channel increases with increasing slip length, due to the contribution of enhanced axial velocity driven by the slip, while there is no fluid-slip dependency for the slip length of less than about 50 nm.

  9. A modeling and simulation framework for electrokinetic nanoparticle treatment

    NASA Astrophysics Data System (ADS)

    Phillips, James

    2011-12-01

    The focus of this research is to model and provide a simulation framework for the packing of differently sized spheres within a hard boundary. The novel contributions of this dissertation are the cylinders of influence (COI) method and sectoring method implementations. The impetus for this research stems from modeling electrokinetic nanoparticle (EN) treatment, which packs concrete pores with differently sized nanoparticles. We show an improved speed of the simulation compared to previously published results of EN treatment simulation while obtaining similar porosity reduction results. We mainly focused on readily, commercially available particle sizes of 2 nm and 20 nm particles, but have the capability to model other sizes. Our simulation has graphical capabilities and can provide additional data unobtainable from physical experimentation. The data collected has a median of 0.5750 and a mean of 0.5504. The standard error is 0.0054 at alpha = 0.05 for a 95% confidence interval of 0.5504 +/- 0.0054. The simulation has produced maximum packing densities of 65% and minimum packing densities of 34%. Simulation data are analyzed using linear regression via the R statistical language to obtain two equations: one that describes porosity reduction based on all cylinder and particle characteristics, and another that focuses on describing porosity reduction based on cylinder diameter for 2 and 20 nm particles into pores of 100 nm height. Simulation results are similar to most physical results obtained from MIP and WLR. Some MIP results do not fall within the simulation limits; however, this is expected as MIP has been documented to be an inaccurate measure of pore distribution and porosity of concrete. Despite the disagreement between WLR and MIP, there is a trend that porosity reduction is higher two inches from the rebar as compared to the rebar-concrete interface. The simulation also detects a higher porosity reduction further from the rebar. This may be due to particles aggregating before reaching the rebar that can easily be seen in the graphical representation of the simulation cylinders. The dissertation author has created a web based framework to allow an interdisciplinary team to work in concert with access to the simulation and the results generated. The results are stored into a MySQL database. The database currently holds 271 simulation runs. Simulation requests can be entered into a web interface and will automatically be processed in the order entered and the results stored into the database. Results can also be retrieved from the database and filtered based on any simulation parameter. Statistical analysis can be completed on the data points stored in the database by using version of Rweb modified by the dissertation author. The result is a collaborative framework that can be extended to address future investigations into pore packing and chloride blocking.

  10. The capture and destruction of chlorinated solvents via electrokinetic pumping: The LASAGNA{trademark} process

    SciTech Connect

    Salvo, J.J.; Ho, S.V.; Shoemaker, S.H.

    1995-12-31

    Remediating soils and groundwater that have been contaminated with chlorinated solvents is a significant challenge for current environmental technology. Soils with a high proportion of fine silts and clays have been especially recalcitrant due to their low permeability. Recently, electrokinetics has shown great promise in gaining access to these contaminated zones that fail to yield with traditional pumping methods. An integrated approach using electrokinetics combined with in situ capture and destruction zones (LASAGNA{sup trademark}) is being developed and field tested by Monsanto, DuPont and GE under the auspices of the EPA`s Remediation Technology Development Forum and with financial support from the Department of Energy. To speed implementation and encourage partnering, royalty-free cross-licensing of the developed technology is available to consortium members for use on their sites.

  11. Field Testing of Rapid Electrokinetic Nanoparticle Treatment for Corrosion Control of Steel in Concrete

    NASA Technical Reports Server (NTRS)

    Cardenas, Henry E.; Alexander, Joshua B.; Kupwade-Patil,Kunal; Calle, Luz Marina

    2009-01-01

    This work field tested the use of electrokinetics for delivery of concrete sealing nanoparticles concurrent with the extraction of chlorides. Several cylinders of concrete were batched and placed in immersion at the Kennedy Space Center Beach Corrosion Test Site. The specimens were batched with steel reinforcement and a 4.5 wt.% (weight percent) content of sodium chloride. Upon arrival at Kennedy Space Center, the specimens were placed in the saltwater immersion pool at the Beach Corrosion Test Site. Following 30 days of saltwater exposure, the specimens were subjected to rapid chloride extraction concurrent with electrokinetic nanoparticle treatment. The treatments were operated at up to eight times the typical current density in order to complete the treatment in 7 days. The findings indicated that the short-term corrosion resistance of the concrete specimens was significantly enhanced as was the strength of the concrete.

  12. Electrokinetic remediation of inorganic and organic pollutants in textile effluent contaminated agricultural soil.

    PubMed

    Annamalai, Sivasankar; Santhanam, Manikandan; Sundaram, Maruthamuthu; Curras, Marta Pazos

    2014-12-01

    The discharge from the dyeing industries constitutes unfixed dyes, inorganic salts, heavy metal complexes etc., which spoil the surrounding areas of industrial sites. The present article reports the use of direct current electrokinetic technique for the treatment of textile contaminated soil. Impressed direct current voltage of 20 V facilitates the dye/metal ions movement in the naturally available dye contaminated soil towards the opposite electrode by electromigration. IrO2–RuO2–TiO2/Ti was used as anode and Ti used as cathode. UV–Visible spectrum reveals that higher dye intensity was nearer to the anode. Ni, Cr and Pb migration towards the cathode and migration of Cu, SO42? and Cl? towards anode were noticed. Chemical oxygen demand in soil significantly decreased upon employing electrokinetic. This technology may be exploited for faster and eco-friendly removal of dye in soil environment. PMID:25461934

  13. TiO2 thin films with rutile phase prepared by DC magnetron co-sputtering at room temperature: Effect of Cu incorporation

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Li, Yujie; Ba, Xin; Huang, Lin; Yu, Ying

    2015-08-01

    The thin films for pure TiO2 and that incorporated with Cu ion were deposited by DC magnetron co-sputtering with Ar gas. The crystal texture, surface morphology, energy gap and optical properties of the prepared films have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectrometer (XPS), UV-vis spectrophotometer, and Raman spectroscopy. The results show that as-deposited TiO2 film mainly possesses anatase structure at room temperature with pure Ar gas, but the introduction of Cu can alter the phase structure of crystallite TiO2. XRD patterns and Raman spectra indicate that the Cu incorporation with high concentration (ACu/ATi + ACu ? 20%) favors the formation of rutile phase. Moreover, the Cu incorporation into TiO2 lattice induces band gap narrowing. Band structures and density of states have been analyzed based on density functional theory (DFT) and periodic models in order to investigate the influence of the Cu incorporation on the electronic structure of TiO2. Both experimental data and electronic structure calculations evidence the fact that the change in film structure from the anatase to the rutile phase can be ascribed to the possible incorporation of Cu1+ in the sites previously occupied by Ti4+, and the presence of Cu results in important effect on the electronic states, which is mainly related to the 3d Cu orbitals in the gap and in the vicinity of the valence band edges for TiO2.

  14. Separation of diastereomeric anthrone-C-glucosyls of aloes by micellar electrokinetic capillary chromatography.

    PubMed

    Liebold, T; Strahler, S; Rauwald, H W

    2007-12-01

    The anthrone-C-glucosyls aloin A and B, 5-hydroxyaloin A, 10-hydroxyaloin A and B were separated by micellar electrokinetic capillary chromatography (MECC) with sodium dodecyl sulfate in borate buffer pH 9 within less than 7 min. The method has been successfully transferred to the analysis of the two European Pharmacopoeia drugs Cape aloes and Curaçao aloes. A comparison of the peak areas received by HPLC and MECC indicated the transferability of the measured contents. PMID:18214350

  15. Micromotors: Trajectory Control of Self-Propelled Micromotors Using AC Electrokinetics (Small 42/2015).

    PubMed

    Yoshizumi, Yoshitaka; Honegger, Thibault; Berton, Kevin; Suzuki, Hiroaki; Peyrade, David

    2015-11-01

    Three-dimensional control over the motion of self-powered Janus micromotors is demonstrated by T. Honegger and co-workers using AC electrokinetics, by applying AC electric fields on transparent indium-tin-oxide electrodes. On page 5630, they show how micromotor direction can be regulated for single or collective motion, applicable to in vitro cell manipulation or drug delivery by chemically modifying micromotors without complicated equipment. PMID:26544801

  16. Simulation of concentration polarization in electrokinetic processes by network thermodynamic methods.

    PubMed Central

    Horno, J; González-Fernández, C F; Hayas, A; González-Caballero, F

    1989-01-01

    Simple techniques of network thermodynamics are used to study the influence of concentration polarization on the determination of electrokinetic properties of physical and biological membrane systems. A network model of the polarization phenomenon resulting from discontinuities in transport numbers between the membrane and their adjacent solutions is proposed. The concentration profiles and potential drop across the membrane in plugs of monodisperse polystyrene particles and in giant algal cells have been simulated using the electrical circuit simulation program SPICE. PMID:2930833

  17. Simulation of concentration polarization in electrokinetic processes by network thermodynamic methods.

    PubMed

    Horno, J; González-Fernández, C F; Hayas, A; González-Caballero, F

    1989-03-01

    Simple techniques of network thermodynamics are used to study the influence of concentration polarization on the determination of electrokinetic properties of physical and biological membrane systems. A network model of the polarization phenomenon resulting from discontinuities in transport numbers between the membrane and their adjacent solutions is proposed. The concentration profiles and potential drop across the membrane in plugs of monodisperse polystyrene particles and in giant algal cells have been simulated using the electrical circuit simulation program SPICE. PMID:2930833

  18. A multiscale theoretical investigation of electric measurements in living bone : piezoelectricity and electrokinetics.

    PubMed

    Lemaire, T; Capiez-Lernout, E; Kaiser, J; Naili, S; Rohan, E; Sansalone, V

    2011-11-01

    This paper presents a theoretical investigation of the multiphysical phenomena that govern cortical bone behaviour. Taking into account the piezoelectricity of the collagen-apatite matrix and the electrokinetics governing the interstitial fluid movement, we adopt a multiscale approach to derive a coupled poroelastic model of cortical tissue. Following how the phenomena propagate from the microscale to the tissue scale, we are able to determine the nature of macroscopically observed electric phenomena in bone. PMID:21347811

  19. Concentric-flow electrokinetic injector enables serial crystallography of ribosome and photosystem II.

    PubMed

    Sierra, Raymond G; Gati, Cornelius; Laksmono, Hartawan; Dao, E Han; Gul, Sheraz; Fuller, Franklin; Kern, Jan; Chatterjee, Ruchira; Ibrahim, Mohamed; Brewster, Aaron S; Young, Iris D; Michels-Clark, Tara; Aquila, Andrew; Liang, Mengning; Hunter, Mark S; Koglin, Jason E; Boutet, Sébastien; Junco, Elia A; Hayes, Brandon; Bogan, Michael J; Hampton, Christina Y; Puglisi, Elisabetta V; Sauter, Nicholas K; Stan, Claudiu A; Zouni, Athina; Yano, Junko; Yachandra, Vittal K; Soltis, S Michael; Puglisi, Joseph D; DeMirci, Hasan

    2016-01-01

    We describe a concentric-flow electrokinetic injector for efficiently delivering microcrystals for serial femtosecond X-ray crystallography analysis that enables studies of challenging biological systems in their unadulterated mother liquor. We used the injector to analyze microcrystals of Geobacillus stearothermophilus thermolysin (2.2-Å structure), Thermosynechococcus elongatus photosystem II (<3-Å diffraction) and Thermus thermophilus small ribosomal subunit bound to the antibiotic paromomycin at ambient temperature (3.4-Å structure). PMID:26619013

  20. Influence of steric interactions on the dielectric and electrokinetic properties in colloidal suspensions.

    PubMed

    López-García, José Juan; Horno, José; Grosse, Constantino

    2015-11-15

    One of the main assumptions of the standard electrokinetic model is that ions behave as point like entities. In this work we remove this assumption and analyze the main consequences of finite ionic size on the dielectric and electrokinetic properties of colloidal suspensions. We represent the steric interactions by means of the Bikerman and the Carnahan-Starling equations and solve numerically the standard linearized electrokinetic equations in the stationary and the frequency domains, for surface charge density and electrolyte solution concentration values typically encountered in colloidal suspensions. In all cases the steric interactions improve upon the predictions of the standard model since the surface potential, the electrophoretic mobility, and the conductivity and permittivity increments increase. However, the corrections introduced by the Bikerman equation are generally small: less than 10% as compared to the standard model. On the contrary, the Carnahan-Starling equation leads to corrections to the surface potential versus surface charge and the electrophoretic mobility values that easily surpass 10% and can attain values as high as 50%. Corrections to the conductivity and permittivity increments are smaller but still non negligible. PMID:26233558

  1. Skin moisturizing effect and skin penetration of ascorbyl palmitate entrapped in solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) incorporated into hydrogel.

    PubMed

    Uner, M; Wissing, S A; Yener, G; Müller, R H

    2005-10-01

    This study was performed as a complimentary to our previous study regarding the chemical stability of ascorbyl palmitate (AP) in solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and for comparison, in nanoemulsion (NE) incorporated into a hydrogel produced by high pressure homogenization. AP is known as an effective antioxidant that protects tissue integrity similar to vitamin C. Recently, its moisturizing activity in conventional topical formulations was found to be high. The aim of the present study was to investigate the moisturizing potential of AP in SLN and NLC incorporated into hydrogel as colloidal carrier systems. It has been known that SLN and NLC have occlusive effects, but AP incorporation moisturized skin significantly better than placebo in short-term (p < 0.001) and long-term trials (p < 0.01) for both SLN and NLC. In the second part of the study, SLN and NLC were found to sustain the penetration of AP through excised human skin about 1/2 and 2/3 times compared to NE (p < 0.001 and p < 0.01), respectively, due to the solid state of Witepsol E85 in the lipid phase. PMID:16259122

  2. Effects of Ta incorporation in La{sub 2}O{sub 3} gate dielectric of InGaZnO thin-film transistor

    SciTech Connect

    Qian, L. X.; Lai, P. T.; Tang, W. M.

    2014-03-24

    The effects of Ta incorporation in La{sub 2}O{sub 3} gate dielectric of amorphous InGaZnO thin-film transistor are investigated. Since the Ta incorporation is found to effectively enhance the moisture resistance of the La{sub 2}O{sub 3} film and thus suppress the formation of La(OH){sub 3}, both the dielectric roughness and trap density at/near the InGaZnO/dielectric interface can be reduced, resulting in a significant improvement in the electrical characteristics of transistor. Among the samples with different Ta contents, the one with a Ta/(Ta?+?La) atomic ratio of 21.7% exhibits the best performance, including high saturation carrier mobility of 23.4?cm{sup 2}/V·s, small subthreshold swing of 0.177?V/dec, and negligible hysteresis. Nevertheless, excessive incorporation of Ta can degrade the device characteristics due to newly generated Ta-related traps.

  3. High Mg effective incorporation in Al-rich Al x Ga1 - x N by periodic repetition of ultimate V/III ratio conditions

    PubMed Central

    2014-01-01

    According to first-principles calculations, the solubility of Mg as a substitute for Ga or Al in Al x Ga1 – x N bulk is limited by large, positive formation enthalpies. In contrast to the bulk case, the formation enthalpies become negative on Al x Ga1 – x N surface. In addition, the N-rich growth atmosphere can also be favorable to Mg incorporation on the surface by changing the chemical potentials. On the basis of these special features, we proposed a modified surface engineering technique that applies periodical interruptions under an ultimate V/III ratio condition (extremely N-rich), to enhance Mg effective incorporation. By optimizing the interruption conditions (2 nm interruption interval with 2 s interruption time), the enhancement ratio can be up to about 5 in the Al0.99Ga0.01N epilayer. PMID:24444104

  4. Effects of Ti incorporation on the interface properties and band alignment of HfTaO{sub x} thin films on sulfur passivated GaAs

    SciTech Connect

    Das, T.; Mahata, C.; Maiti, C. K.; Miranda, E.; Sutradhar, G.; Bose, P. K.

    2011-01-10

    Thin HfTaO{sub x} and HfTaTiO{sub x} gate dielectrics ({approx}7-8 nm) have been rf sputter-deposited on sulfur passivated GaAs. Our experimental results suggest that the formation of Ga-O at GaAs surface and As diffusion in dielectric may be effectively controlled by Ti incorporation. Possibility of tailoring of band alignment via Ti incorporation is shown. Valence band offsets of 2.6{+-}0.05 and 2.68{+-}0.05 eV and conduction-band offsets of 1.43{+-}0.05 and 1.05{+-}0.05 eV were found for HfTaO{sub x} (E{sub g{approx}}5.45 eV) and HfTaTiO{sub x} (E{sub g{approx}}5.15 eV), respectively.

  5. Effect of heat treatment on the structure of incorporated oxalate species and photoluminescent properties of porous alumina films formed in oxalic acid

    NASA Astrophysics Data System (ADS)

    Vrublevsky, I.; Jagminas, A.; Hemeltjen, S.; Goedel, W. A.

    2008-09-01

    The present work focuses on the use of IR spectroscopy and photoluminescence spectral measurements for studying the treatment temperature effect on the compositional and luminescent properties of oxalic acid alumina films. In line with the recent researches we have also found that heat treatment of porous alumina films formed in oxalic acid leads to considerable changes in their photoluminescence properties: upon annealing the intensity of photoluminescence (PL) increases reaching a maximum at the temperature of around 500 °C and then decreases. IR spectra of as-grown and heat-treated films have proved that PL emission in the anodic alumina films is related with the state of 'structural' oxalate species incorporated in the oxide lattice. These results allowed us to conclude that PL behavior of oxalic acid alumina films can be explained through the concept of variations in the bonding molecular orbitals of incorporated oxalate species including ?- and ?-bonds.

  6. The effect of Ce{sup 4+} incorporation on structural, morphological and photocatalytic characters of ZnO nanoparticles

    SciTech Connect

    Kannadasan, N.; Shanmugam, N. Cholan, S.; Sathishkumar, K.; Viruthagiri, G.; Poonguzhali, R.

    2014-11-15

    We report a simple chemical precipitation method for the preparation of undoped and cerium doped ZnO nanocrystals. The concentration of cerium in the products can be controlled in the range of 0.025–0.125 mol. The structure and chemical compositions of the products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy; energy dispersive spectrum and Fourier transform infrared spectroscopy. The results demonstrate that Ce{sup 4+} ions were successfully incorporated into the lattice position of Zn{sup 2+} ions in ZnO. The morphology of the products was analyzed by field emission scanning electron microscopy and confirmed by high resolution transmission electron microscope analysis. The optical properties of the products were studied by ultraviolet–visible and room temperature photoluminescence measurements. The photoluminescence emission spectra of Ce-doped ZnO showed enhanced visible emissions as a result of 5d ? 4f transition of cerium. In particular, a novel photocatalytic activity of the products was assessed using methylene blue. The obtained result reveals that Ce-doped products show higher reduction efficiency for methylene blue than the undoped ZnO. - Highlights: • Nanocrystals of ZnO and ZnO:Ce{sup 4+} were grown. • XPS results confirmed the incorporated cerium in tetravalence. • PL emission exhibited 5d ? 4f transition on cerium doping. • Doped ZnO decolorizes MB faster than undoped ZnO.

  7. Effect of a Smartphone Application Incorporating Personalized Health-Related Imagery on Adherence to Antiretroviral Therapy: A Randomized Clinical Trial

    PubMed Central

    Perera, Anna I.; Thomas, Mark G.; Moore, John O.; Faasse, Kate

    2014-01-01

    Abstract Poor adherence to combination antiretroviral therapy (ART) is a major global challenge. In this study we examined the efficacy of a smartphone application incorporating personalized health-related visual imagery that provided real-time information about the level of medication and the patient's level of immunoprotection, in order to improve adherence to ART. We randomized 28 people on ART to either a standard or augmented version of the smartphone application. The augmented version contained components that illustrated participants' current estimated plasma concentrations of antiretroviral drugs and the immune protection provided by ART. Adherence to ART was assessed at baseline and at 3 months using self-reported adherence, pharmacy dispensing records, and HIV viral load. Information was also collected on illness and medication beliefs and use of the application. Participants who received the augmented application showed a significantly higher level of self-reported adherence to ART at 3 months (p=0.03) and decreased viral load (p=0.023) as compared to individuals using the standard version. Greater usage of the extra components of the augmented application was associated with greater perceived understanding of HIV infection and increased perceived necessity for ART. Smartphone applications that incorporate personalized health-related visual imagery may have potential to improve adherence to ART. PMID:25290556

  8. Evaluation of sintering effects on SiC incorporated UO2 kernels under Ar and Ar-4%H2 environments

    SciTech Connect

    Silva, Chinthaka M; Lindemer, Terrence; Hunt, Rodney Dale; Collins, Jack Lee; Terrani, Kurt A; Snead, Lance Lewis

    2013-01-01

    Silicon carbide (SiC) is suggested as an oxygen getter in UO2 kernels used for TRISO particle fuels to lower oxygen potential and prevent kernel migration during irradiation. Scanning electron microscopy and X-ray diffractometry analyses performed on sintered kernels verified that internal gelation process can be used to incorporate SiC in urania fuel kernels. Sintering in either Ar or Ar-4%H2 at 1500 C lowered the SiC content in the UO2 kernels to some extent. Formation of UC was observed as the major chemical phase in the process, while other minor phases such as U3Si2C2, USi2, U3Si2, and UC2 were also identified. UC formation was presumed to be occurred by two reactions. The first was the SiC reaction with its protective SiO2 oxide layer on SiC grains to produce volatile SiO and free carbon that subsequently reacted with UO2 to form UC. The second process was direct UO2 reaction with SiC grains to form SiO, CO, and UC, especially in Ar-4%H2. A slightly higher density and UC content was observed in the sample sintered in Ar-4%H2, but the use of both atmospheres produced kernels with ~95% of theoretical density. It is suggested that incorporating CO in the sintering gas would prevent UC formation and preserve the initial SiC content.

  9. Incorporation effect of nanosized perovskite LaFe?.?Co?.?O? on the electrochemical activity of Pt nanoparticles-multi walled carbon nanotube composite toward methanol oxidation

    SciTech Connect

    Noroozifar, Meissam; Khorasani-Motlagh, Mozhgan; Khaleghian-Moghadam, Roghayeh; Ekrami-Kakhki, Mehri-Saddat; Shahraki, Mohammad

    2013-05-01

    Nanosized perovskite LaFe?.?Co?.?O? (LFCO) is synthesized through conventional co-precipitation method and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. The incorporation effect of the mentioned perovskite to catalytic activity of the PtNPs-MWCNTs-nafion (or -chitosan) catalyst toward methanol oxidation has been studied by cyclic voltammetry. Based on the electrochemical studies, all MWCNTs-PtNPs-nafion (or chitosan) and MWCNTs-PtNPs-LFCO-nafion (or chitosan) catalysts show a considerable activity for methanol oxidation. However, a synergistic effect is observed when LFCO is added to the catalyst by decreasing the poisoning rate of the Pt catalyst. - Graphical abstract: Nanosized perovskite LaFe?.?Co?.?O? is synthesized and characterized. The incorporation effect of the mentioned perovskite to catalytic activity of the PtNPS-MWCNTs-nafion (or -chitosan) catalyst toward methanol oxidation is studied. Highlights: • Nanocrystalline LaFe?.?Co?.?O? (LFCO) is prepared by a new simple co-precipitation method. • Effect of LFCO to catalytic activity of PtNPS for methanol oxidation is studied. • A synergistic effect is observed when LFCO is added to the Pt catalyst. • Oxygen of LFCO could be considered as active oxygen to remove CO intermediates.

  10. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier.

    PubMed

    Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

    2015-01-01

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR?+?PRB showed the lowest leaching value for each HM in the S2 and S3 regions. PMID:26486449

  11. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier

    PubMed Central

    Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

    2015-01-01

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR?+?PRB showed the lowest leaching value for each HM in the S2 and S3 regions. PMID:26486449

  12. Application of biosurfactants and periodic voltage gradient for enhanced electrokinetic remediation of metals and PAHs in dredged marine sediments.

    PubMed

    Ammami, M T; Portet-Koltalo, F; Benamar, A; Duclairoir-Poc, C; Wang, H; Le Derf, F

    2015-04-01

    Dredged harbor sediment co-contaminated by heavy metals and polycyclic aromatic hydrocarbons (PAHs) was subjected to enhanced electrokinetic treatments, using a mixture of a chelating agent (citric acid CA) and a surfactant as additives in the processing fluids. We tested various operating conditions (at 1 V cm(-1)): different CA concentrations, applying a periodic voltage gradient, pre-conditioning the sediment with the additives, and replacing the synthetic surfactant Tween 20 (TW20) by biosurfactants. Increasing the CA concentration was favorable for both metal and PAH removal. Applying a periodic voltage gradient associated to a low concentration of CA and TW20 provided the best results for Zn, Cd and Pb removal and also for removal of the 16 priority PAHs. Promising results were obtained with solutions containing rhamnolipids (0.028%) and a viscosin-like biosurfactant produced by Pseudomonas fluorescens Pfa7B (0.025%), associated to a periodic voltage gradient. Although the rhamnolipid and the viscosin-like compounds involved a higher electrical current than TW20, metals were less removed from the sediment. The electroosmotic flow was lower when we used biosurfactants, hence a less effective effect on PAH removal. PMID:25644703

  13. Heavy metal removal from MSWI fly ash by electrokinetic remediation coupled with a permeable activated charcoal reactive barrier

    NASA Astrophysics Data System (ADS)

    Huang, Tao; Li, Dongwei; Kexiang, Liu; Zhang, Yuewei

    2015-10-01

    This paper presents the investigations into the feasibility of the application of a remediation system that couples electrokinetic remediation (EKR) with the permeable reactive barrier (PRB) concept for municipal solid waste incineration (MSWI) fly ash with activated charcoal as the PRB material. The experimental results of this study showed that the proposed combined method can effectively improve the remediation efficiency and that the addition of the oxalic acid to the PRB media before the coupled system can further enhance the remediation process. In the optimization tests, the maximum removals of Zn, Pb, Cu and Cd were achieved under different experimental conditions. The voltage gradient and processing time were shown to have significant effects on the removal of Cu and Cd, whereas the addition of the oxalic acid had a more significant influence on the removal of Pb. Generally, the processing time is the most significant factor in changing the removal rates of HMs in the enhanced coupled system. In terms of the leaching toxicity, the specimen remediated by ENEKR?+?PRB showed the lowest leaching value for each HM in the S2 and S3 regions.

  14. In situ consolidation of offshore petroleum well structural casings by electrokinetic methods

    NASA Astrophysics Data System (ADS)

    Wrixon, Robert Christopher

    Offshore drilling operations encounter cement wash-out problems while setting the initial structural casing (0--200 ft depth) due to the soft, unconsolidated nature of the sea-bed. Structural casings set by alternative methods have failed in up to 50% of cases due to insufficient frictional bearing capacity. This dissertation presents a method of increasing the bearing capacity of a jet-drilled or slick-drilled casing in-situ by applying a potential difference such that the casing is anodic compared to a remote cathode. It has been shown experimentally that clayey formations will swell and stick to a simulated anodic casing by the combined electrokinetic processes of electroosmosis and electrophoresis. Any cavities around the "casing" are eliminated and the formation is flush against the metal surface, increasing bearing capacity. The formation around the "casing" dries out due to electroosmotic migration of water away from the anode, increasing the shear strength of the surrounding soil. Corrosion products at the anode can further increase the soil shear strength by a process known as electrochemical hardening. This investigation has shown that the bearing capacity of anodic casings can potentially be increased by a factor of up to 1,000% in soft clays and silty clays. The existence of an optimal level of electrokinetic consolidation, beyond which the soil shear strength begins to degrade, has been demonstrated. The difficulties of applying electrokinetic methods to saline soil environments have been addressed and the process has been shown to be successful, as long as the requisite electric field strength is maintained. The efficiency of the electrokinetic consolidation technique has been shown to be affected by the soil water content, soil mineralogy, power supplied, time of treatment and the choice of anode material. Experiments in marine sediment show that increases in bearing capacities of about 300% can be achieved at optimal treatment conditions. With likely current and power restrictions, increases of 50% to 100% are realistic. This level of increase still makes offshore electrokinetic casing consolidation a viable process, given that it is attainable quickly and at a modest power requirement and given the enormous cost of a structural casing collapse.

  15. Effects of dicyclohexylamine on polyamine biosynthesis and incorporation into turnip yellow mosaic virus in Chinese cabbage protoplasts infected in vitro

    SciTech Connect

    Balint, R.; Cohen, S.S.

    1985-07-15

    The authors have reported that protoplasts from plants infected with turnip yellow mosaic virus (TYMV) continue to produce virus in culture and that newly formed virus particles contained predominantly newly synthesized spermidine and spermine. They now report similar results with healthy protoplasts infected in vitro, in which essentially all of the virus is newly formed. Again, newly synthesized spermidine and spermine were preferentially incorporated into virus. DCHA inhibited spermidine synthesis by 85%, leading in 20 hr to a 60% depletion of the cellular spermidine and a 30% reduction in the amount of spermidine per virion. Spermine synthesis increased, however, producing a 40% increase in cellular spermine and 50-100% increase in the amount of spermine per virion. Thus, in spite of spermidine depletion, the total positive charge contributed by polyamines to the virus was essentially conserved.

  16. What dental educators need to understand about emerging technologies to incorporate them effectively into the educational process.

    PubMed

    Stein, Corey D; Eisenberg, Elise S; O'Donnell, Jean A; Spallek, Heiko

    2014-04-01

    Many dental schools are currently struggling with the adoption of emerging technologies and the incorporation of these technologies into the educational process. Dental students exhibit an increasing degree of digital comfort when using social networking, mobile devices, search engines, or e-textbooks. Although the majority of students might consider themselves to be very skilled at using information technology, many faculty members would claim the opposite when evaluating their own knowledge and skills in the use of technology. As the use of technology, both formally and informally, continues to increase, dental educators are faced with many questions, such as: Does students' digital comfort disguise a lack of information literacy? What is the appropriate path of implementing technology into teaching and learning, and how can institutions support such an implementation? This article surveys a series of myths that exist about the use of technology in education and raises questions about their validity and how dental educators can avoid being misled by them. PMID:24706681

  17. Microemulsion electrokinetic chromatography: an application for the simultaneous determination of suspected fragrance allergens in rinse-off products.

    PubMed

    Furlanetto, Sandra; Orlandini, Serena; Giannini, Iacopo; Pasquini, Benedetta; Pinzauti, Sergio

    2010-11-15

    A mixture of 18 neutral UV-active compounds with different characteristics of polarity was determined by capillary electrophoresis using a pseudostationary phase constituted by a microemulsion. The test analytes were volatile fragrance compounds, included in a list of 24 chemicals classified as suspected allergens according to Directive 2003/15/CE. The considered compounds were detected at 195 nm and p-anisaldehyde was chosen as internal standard. The background electrolyte consisted of a standard microemulsion made of 90.95% 10mM borax buffer, pH 9.2, 1.05% n-heptane, 8.00% SDS/n-butanol in 1:2 ratio, to which 40 mM methyl-?-cyclodextrin was added. Temperature and voltage were set at 20 °C and 25 kV, respectively. These experimental conditions allowed separation of the compounds to be obtained in about 20 min. The method was applied to real samples made up of rinse-off scented products. The results obtained using the standard microemulsion as pseudostationary phase showed its high resolution power, capable of effectively separating a complex mixture of analytes. Microemulsion electrokinetic chromatography was confirmed to have a great potential for different analytical challenges, holding up the possibility of using this technique as a good and complementary alternative to HPLC methods for routine analysis. PMID:21035646

  18. Rapid Particle Patterning in Surface Deposited Micro-Droplets of Low Ionic Content via Low-Voltage Electrochemistry and Electrokinetics

    PubMed Central

    Sidelman, Noam; Cohen, Moshik; Kolbe, Anke; Zalevsky, Zeev; Herrman, Andreas; Richter, Shachar

    2015-01-01

    Electrokinetic phenomena are a powerful tool used in various scientific and technological applications for the manipulation of aqueous solutions and the chemical entities within them. However, the use of DC-induced electrokinetics in miniaturized devices is highly limited. This is mainly due to unavoidable electrochemical reactions at the electrodes, which hinder successful manipulation. Here we present experimental evidence that on-chip DC manipulation of particles between closely positioned electrodes inside micro-droplets can be successfully achieved, and at low voltages. We show that such manipulation, which is considered practically impossible, can be used to rapidly concentrate and pattern particles in 2D shapes in inter-electrode locations. We show that this is made possible in low ion content dispersions, which enable low-voltage electrokinetics and an anomalous bubble-free water electrolysis. This phenomenon can serve as a powerful tool in both microflow devices and digital microfluidics for rapid pre-concentration and particle patterning. PMID:26293477

  19. Rapid Particle Patterning in Surface Deposited Micro-Droplets of Low Ionic Content via Low-Voltage Electrochemistry and Electrokinetics

    NASA Astrophysics Data System (ADS)

    Sidelman, Noam; Cohen, Moshik; Kolbe, Anke; Zalevsky, Zeev; Herrman, Andreas; Richter, Shachar

    2015-08-01

    Electrokinetic phenomena are a powerful tool used in various scientific and technological applications for the manipulation of aqueous solutions and the chemical entities within them. However, the use of DC-induced electrokinetics in miniaturized devices is highly limited. This is mainly due to unavoidable electrochemical reactions at the electrodes, which hinder successful manipulation. Here we present experimental evidence that on-chip DC manipulation of particles between closely positioned electrodes inside micro-droplets can be successfully achieved, and at low voltages. We show that such manipulation, which is considered practically impossible, can be used to rapidly concentrate and pattern particles in 2D shapes in inter-electrode locations. We show that this is made possible in low ion content dispersions, which enable low-voltage electrokinetics and an anomalous bubble-free water electrolysis. This phenomenon can serve as a powerful tool in both microflow devices and digital microfluidics for rapid pre-concentration and particle patterning.

  20. The effects of atmospheric [CO2] on carbon isotope fractionation and magnesium incorporation into biogenic marine calcite

    NASA Technical Reports Server (NTRS)

    Vieira, Veronica

    1997-01-01

    The influences of atmospheric carbon dioxide on the fractionation of carbon isotopes and the magnesium incorporation into biogenic marine calcite were investigated using samples of the calcareous alga Amphiroa and benthic foraminifer Sorites grown in the Biosphere 2 Ocean system under variable atmospheric CO2 concentrations (approximately 500 to 1200 ppm). Carbon isotope fractionation was studied in both the organic matter and the skeletal carbonate. Magnesium analysis was to be performed on the carbonate removed during decalcification. These data have not been collected due to technical problems. Carbon isotope data from Amphiroa yields a linear relation between [CO2] and Delta(sup 13)C(sub Corg)values suggesting that the fractionation of carbon isotopes during photosynthesis is positively correlated with atmospheric [CO2]. [CO2] and Delta(sup 13)C(sub Corg) values for Sorites produce a relation that is best described by a hyperbolic function where Delta(sup 13)C(sub Corg) values increase between 300 and 700 ppm and decrease from 700 to 1200 ppm. Further investigation of this relation and Sorites physiology is needed.

  1. Palmitoylation of the feline immunodeficiency virus envelope glycoprotein and its effect on fusion activity and envelope incorporation into virions

    SciTech Connect

    Gonzalez, Silvia A.; Paladino, Monica G.; Affranchino, Jose L.

    2012-06-20

    The feline immunodeficiency virus (FIV) envelope glycoprotein (Env) possesses a short cytoplasmic domain of 53 amino acids containing four highly conserved cysteines at Env positions 804, 811, 815 and 848. Since palmitoylation of transmembrane proteins occurs at or near the membrane anchor, we investigated whether cysteines 804, 811 and 815 are acylated and analyzed the relevance of these residues for Env functions. Replacement of cysteines 804, 811 and 815 individually or in combination by serine residues resulted in Env glycoproteins that were efficiently expressed and processed. However, mutations C804S and C811S reduced Env fusogenicity by 93% and 84%, respectively, compared with wild-type Env. By contrast, mutant C815S exhibited a fusogenic capacity representing 50% of the wild-type value. Remarkably, the double mutation C804S/C811S abrogated both Env fusion activity and Env incorporation into virions. Finally, by means of Click chemistry assays we demonstrated that the four FIV Env cytoplasmic cysteines are palmitoylated.

  2. Analysis of illicit drugs in human urine by micellar electrokinetic capillary chromatography with on-column fast scanning polychrome absorption detection.

    PubMed

    Wernly, P; Thormann, W

    1991-12-15

    Using micellar electrokinetic capillary chromatography (MECC) with a borate/phosphate buffer containing 75 mM SDS (pH 9.1), common drugs of abuse and/or their metabolites, including opioids, benzoylecgonine, amphetamines, and methaqualone, can easily be analyzed. After solid-phase extraction of 5 mL of urine, drug concentrations down to about 100 ng/mL can be unambiguously monitored with on-column multiwavelength detection. Peak assignment is achieved through comparison of retention times and absorption spectra of eluting peaks with those of computer-stored model runs. The effectiveness of the approach is demonstrated with data obtained from different patient urines which tested positively for one or several drugs using nonisotopic immunoassays. Results suggest that MECC of illicit drugs is a highly specific and sensitive instrumental approach suitable for confirmation testing following a positive response of a toxicological screening procedure. PMID:1789451

  3. A comparative analysis of XV-15 tiltrotor hover test data and WOPWOP predictions incorporating the fountain effect

    NASA Technical Reports Server (NTRS)

    Rutledge, Charles K.; Coffen, Charles D.; George, Albert R.

    1991-01-01

    Acoustic measurements from a hovering full scale XV-15 tilt rotor with the advanced technology blades are presented which show the directionality of fountain effect noise. Predicted acoustic directivity results are also presented which show agreement with the measured data. The aeroacoustic code, WOPWOP, was used in conjunction with a mathematical model which simulated the fountain recirculation aerodynamic effect on the rotor blade surface pressures. The predictions were used to identify the spike character in the measured data as fountain effect associated noise. The directivity of the fountain effect noise was observed to be dominant at the rear of the aircraft with increased intensities 45 degrees below the rotor disk planes.

  4. The effect of incorporated self-lubricated BN(h) particles on the tribological properties of Ni-P/BN(h) composite coatings

    NASA Astrophysics Data System (ADS)

    Hsu, Chih-I.; Hou, Kung-Hsu; Ger, Ming-Der; Wang, Gao-Liang

    2015-12-01

    Ni-P/BN(h) composite coatings are prepared by means of the conventional electroless plating from the bath containing up to 10.0 g/l of hexagonal boron nitride particles with size 0.5 ?m. The Ni-P coating is also prepared as a comparison. Cationic surfactant cetyltrimethylammonium bromide (CTAB) is used to stabilize the electrolyte, and the optimum CTAB concentration resulting in a nonagglomerated dispersion of particles is obtained using a dispersion stability analyzer. Morphology of the coatings and the effect of incorporated particles on coating structure and composition are investigated via scanning electron microscopy, field emission electron probe micro-analyzer and X-ray diffraction analysis. Hardness, roughness, friction coefficient and wear resistance of the coatings are also evaluated using Vickers microhardness tester, atomic force microscopy and ball-on disk machine. The presence of CTAB in the depositing bath has a positive effect on the surface roughness and performance of Ni-P/BN(h) composite coatings. The friction and wear tests results show that incorporation of 14.5 vol% BN(h) particles into the Ni-P coating lowers the coating friction coefficient by about 75% and the wear resistance of the Ni-P composites is approximately 10 times higher than Ni-P coating.

  5. Nutrient digestibility of Mucuna (Mucuna pruriens var. utilis) bean in guinea fowl (Numida meleagris, L): Effects of heat treatment and levels of incorporation in diets.

    PubMed

    Dahouda, M; Toléba, S S; Youssao, A K I; Hambuckers, A; Dangou-Sapoho, R; Martin, G B; Fillet, M; Hornick, J-L

    2009-09-01

    1. Mucuna pruriens var. utilis is a legume, the seeds of which are scarcely used in animal diets owing to their high content of 3,4-dihydroxy-L-phenylalanine (L-Dopa). 2. Experiments were conducted on guinea fowl to assess the effects of two types of heat processing (cooking and toasting) on chemical composition and nutrient digestibility of Mucuna seeds offered alone or incorporated at three concentrations (40, 120 or 200 g/kg) in complete diets. 3. Diets containing 200 g/kg seeds had more crude fibre and less ether extract. L-Dopa content increased with the amount of Mucuna inclusion. Cooking reduced markedly L-Dopa content while toasting had no effect. When fed alone, Mucuna seeds dramatically decreased feed intake. 4. Feed intake (FI) and body weight gain (BWG) were not influenced by the complete diets. Cooking significantly increased crude fibre digestibility. 5. It is suggested that cracked and cooked Mucuna bean can be incorporated at a safe level of 120 g/kg in complete diets for guinea fowl production. PMID:19904635

  6. Monte Carlo model incorporating many-body effects for determining the gain spectra of quantum dot lasers

    NASA Astrophysics Data System (ADS)

    Peyvast, Negin; Shahid, Hifsa; Hogg, Richard A.; Childs, David T. D.

    2015-12-01

    We present a Monte Carlo model that simulates the gain spectra of a QD laser material that empirically includes free-carrier effects. We compare simulation results of both Fermi–Dirac and random carrier populations, and compare them with experimental data. The free-carrier effects are highlighted as being more important than the choice of carrier statistics, and routes to improve this simple model are discussed.

  7. The Electrokinetic Mechanism of Hydrothermal-Circulation-Related and Production-Induced Self-Potentials

    SciTech Connect

    Ishido, T.; Kikuchi, T.; Sugihara, M.

    1987-01-20

    Self-potential (SP) surveys were carried out on a number of geothermal areas in Japan during the last decade. In most cases SP anomalies of positive polarity are found to overlie high temperature upflow zones. Streaming potential generated by hydrothermal circulation (Ishido, 1981) is considered to be the most likely cause of the observed positive anomalies. Repeated surveys conducted on the Nigorikawa caldera in Japan detected a change in SP induced by production of geothermal fluids. The observed change is dipolar in waveform and can also be attributed to an electrokinetic mechanism. 6 figs., 14 refs.

  8. A multiphase electrokinetic flow model for electrolytes with liquid/liquid interfaces

    SciTech Connect

    Berry, J.D. Davidson, M.R. Harvie, D.J.E.

    2013-10-15

    A numerical model for electrokinetic flow of multiphase systems with deformable interfaces is presented, based on a combined level set-volume of fluid technique. A new feature is a multiphase formulation of the Nernst–Planck transport equation for advection, diffusion and conduction of individual charge carrier species that ensures their conservation in each fluid phase. The numerical model is validated against the analytical results of Zholkovskij et al. (2002) [1], and results for the problem of two drops coalescing in the presence of mobile charge carriers are presented. The time taken for two drops containing ions to coalesce decreases with increasing ion concentration.

  9. Evaluation of micellar electrokinetic capillary chromatography for the analysis of selected tobacco alkaloids.

    PubMed

    Yang, S S; Smetena, I; Goldsmith, A I

    1996-10-01

    Micellar electrokinetic capillary chromatography was evaluated for simultaneous determination of several tobacco alkaloids with similar molecular structure. Satisfactory separation of nicotine, nornicotine, myosmine, anatabine and anabasine extracted from tobacco was achieved by introducing an ionic surfactant, sodium dodecyl sulfate, into the buffer system at a concentration of 100 mM. Sample preparation involved a single extraction with water containing 1% triethanolamine. Separation was performed on a 72 cm long, uncoated fused-silica capillary. Experimental parameters such as applied voltage, pH value, buffer composition and surfactant concentration were optimized. Enhancement of UV absorption of alkaloids in the presence of micelles was also studied. PMID:8885385

  10. Evaluation of the separation mechanism of electrokinetic chromatography with a microemulsion and cyclodextrins using NMR and molecular modeling.

    PubMed

    Melani, Fabrizio; Giannini, Iacopo; Pasquini, Benedetta; Orlandini, Serena; Pinzauti, Sergio; Furlanetto, Sandra

    2011-11-01

    Electrokinetic chromatography (EKC) allows the separation of closely related substances by the detection of fine effects in analyte-separation system interactions. With the goal of understanding the fine effects involved in separation using a dual cyclodextrin-microemulsion EKC system, an integrated study of NMR and molecular modeling was carried out. The above dual cyclodextrin-microemulsion system was previously used in the separation of clemastine and its related substances and was prepared by the addition of methyl-?-cyclodextrin (M?CD) and heptakis(2,6-di-O-methyl)-?-cyclodextrin (DM?CD) to an oil-in-water microemulsion. The use of DM?CD was shown to be essential in the separation of clemastine from one of its related substance (I(B) ). A molecular modeling study allowed the different affinities of clemastine and I(B) for the two cyclodextrins to be explained. Furthermore, rotating-frame Overhauser effect spectroscopy NMR experiments clearly indicated that besides the primary pseudostationary phase, namely the ionic microemulsion, cyclodextrins acted as a secondary pseudostationary phase. In addition, it was shown that inclusion complexation of sodium dodecyl sulfate (SDS) monomers into the cyclodextrins cavity occurs; differently, the oil (n-heptane) used in the preparation of microemulsion system resulted to be not included into the macrocycle cavity. These experimental results were supported by molecular modeling, which highlighted the preferential inclusion of SDS into DM?CD. On the basis of these results, it was confirmed that, besides its primary role as the ionic carrier in EKC, SDS is involved in inclusion equilibria toward CDs, which can be effective in increasing the system selectivity. PMID:22002863

  11. Effect of acid or alkaline catalyst and of different capping agents on the optical properties of CdS nanoparticles incorporated within a diureasil hybrid matrix

    NASA Astrophysics Data System (ADS)

    Gonçalves, Luis F. F. F.; Silva, Carlos J. R.; Kanodarwala, Fehmida K.; Stride, John A.; Pereira, Mario R.

    2015-11-01

    CdS nanoparticles (NPs) were synthesized using colloidal methods and incorporated within a diureasil hybrid matrix. The surface capping of the CdS NPs by 3-mercaptopropyltrimethoxysilane (MPTMS) and 3-aminopropyltrimethoxysilane (APTMS) organic ligands during the incorporation of the NPs within the hybrid matrix has been investigated. The matrix is based on poly(ethylene oxide)/poly(propylene oxide) chains grafted to a siliceous skeleton through urea bonds and was produced by sol-gel process. Both alkaline and acidic catalysis of the sol-gel reaction were used to evaluate the effect of each organic ligand on the optical properties of the CdS NPs. The hybrid materials were characterized by absorption, steady-state and time-resolved photoluminescence spectroscopy and High Resolution Transmission Electron Microscopy (HR-TEM). The preservation of the optical properties of the CdS NPs within the diureasil hybrids was dependent on the experimental conditions used. Both organic ligands (APTMS and MPTMS) demonstrated to be crucial in avoiding the increase of size distribution and clustering of the NPs within the hybrid matrix. The use of organic ligands was also shown to influence the level of interaction between the hybrid host and the CdS NPs. The CdS NPs showed large Stokes shifts and long average lifetimes, both in colloidal solution and in the xerogels, due to the origin of the PL emission in surface states. The CdS NPs capped with MPTMS have lower PL lifetimes compared to the other xerogel samples but still larger than the CdS NPs in the original colloidal solution. An increase in PL lifetimes of the NPs after their incorporation within the hybrid matrix is related to interaction between the NPs and the hybrid host matrix.

  12. IMMUNOSTIMULATING COMPLEXES INCORPORATING E. TENELLA ANTIGENS AND PLANT SAPONINS AS AN EFFECTIVE DELIVERY SYSTEM FOR COCCIDIA VACCINE IMMUNIZATION.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Immunostimulating complexes (ISCOMs) are a unique, multimolecular structure formed by encapsulating antigens, lipids and triterpene saponins of plant origin and are an effective delivery system for various kinds of antigens. The uses of ISCOMs formulated with saponins from plants native to Kazakhs...

  13. Fish protein substrates can substitute effectively for poultry by-product meal when incorporated in high quality senior dog diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An experiment was conducted to analytically define several novel fish substrates and determine the effects of feeding diets containing these substrates on total tract nutrient digestibility and on immune status of senior dogs. The control diet contained poultry by-product meal while test diets cont...

  14. Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hans, M.; to Baben, M.; Music, D.; Ebenhöch, J.; Primetzhofer, D.; Kurapov, D.; Arndt, M.; Rudigier, H.; Schneider, J. M.

    2014-09-01

    Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds.

  15. Effect of oxygen incorporation on the structure and elasticity of Ti-Al-O-N coatings synthesized by cathodic arc and high power pulsed magnetron sputtering

    SciTech Connect

    Hans, M. Baben, M. to; Music, D.; Ebenhöch, J.; Schneider, J. M.; Primetzhofer, D.; Kurapov, D.; Arndt, M.; Rudigier, H.

    2014-09-07

    Ti-Al-O-N coatings were synthesized by cathodic arc and high power pulsed magnetron sputtering. The chemical composition of the coatings was determined by means of elastic recoil detection analysis and energy dispersive X-ray spectroscopy. The effect of oxygen incorporation on the stress-free lattice parameters and Young's moduli of Ti-Al-O-N coatings was investigated by X-ray diffraction and nanoindentation, respectively. As nitrogen is substituted by oxygen, implications for the charge balance may be expected. A reduction in equilibrium volume with increasing O concentration is identified by X-ray diffraction and density functional theory calculations of Ti-Al-O-N supercells reveal the concomitant formation of metal vacancies. Hence, the oxygen incorporation-induced formation of metal vacancies enables charge balancing. Furthermore, nanoindentation experiments reveal a decrease in elastic modulus with increasing O concentration. Based on ab initio data, two causes can be identified for this: First, the metal vacancy-induced reduction in elasticity; and second, the formation of, compared to the corresponding metal nitride bonds, relatively weak Ti-O and Al-O bonds.

  16. Analysis of Improved Government Geological Map Information for Mineral Exploration: Incorporating Efficiency, Productivity, Effectiveness, and Risk Considerations

    USGS Publications Warehouse

    Bernknopf, R.L.; Wein, A.M.; St-Onge, M. R.; Lucas, S.B.

    2007-01-01

    This bulletin/professional paper focuses on the value of geoscientific information and knowledge, as provided in published government bedrock geological maps, to the mineral exploration sector. An economic model is developed that uses an attribute- ranking approach to convert geological maps into domains of mineral favourability. Information about known deposits in these (or analogous) favourability domains allow the calculation of exploration search statistics that provide input into measures of exploration efficiency, productivity, effectiveness, risk, and cost stemming from the use of the published geological maps. Two case studies, the Flin Flon Belt (Manitoba and Saskatchewan) and the south Baffin Island area (Nunavut), demonstrate that updated, finer resolution maps can be used to identify more exploration campaign options, and campaigns thats are more efficient, more effective, and less risky than old, coarser resolution maps when used as a guide for mineral exploration. The Flin Flon Belt study illustrates that an updated, coarser resolution bedrock map enables improved mineral exploration efficiency, productivity, and effectiveness by locating 60% more targets and supporting an exploration campaign that is 44% more efficient. Refining the map resolution provides an additional 17% reduction in search effort across all favourable domains and a 55% reduction in search effort in the most favourable domain. The south Baffin Island case study projects a 40% increase in expected targets and a 27% reduction in search effort when the updated, finer resolution map is used in lieu of the old, coarser resolution map. On southern Baffin Island, the economic value of the up dated map ranges from CAN$2.28 million to CAN$15.21 million, which can be compared to the CAN$1.86 million that it cost to produce the map (a multiplier effect of up to eight).

  17. Effective DQE (eDQE) for monoscopic and stereoscopic chest radiography imaging systems with the incorporation of anatomical noise

    SciTech Connect

    Boyce, Sarah J.; Choudhury, Kingshuk Roy; Samei, Ehsan; Carl E. Ravin Advanced Imaging Laboratories, Department of Biomedical Engineering, Duke University, Durham, North Carolina 27705; Carl E. Ravin Advanced Imaging Laboratories, Department of Physics, Duke University, Durham, North Carolina 27705

    2013-09-15

    Purpose: Stereoscopic chest biplane correlation imaging (stereo/BCI) has been proposed as an alternative modality to single view chest x-ray (CXR). The metrics effective modulation transfer function (eMTF), effective normalized noise power spectrum (eNNPS), and effective detective quantum efficiency (eDQE) have been proposed as clinically relevant metrics for assessing clinical system performance taking into consideration the magnification and scatter effects. This study compared the metrics eMTF, eNNPS, eDQE, and detectability index for stereo/BCI and single view CXR under isodose conditions at two magnifications for two anthropomorphic phantoms of differing sizes.Methods: Measurements for the eMTF were taken for two phantom sizes with an opaque edge test device using established techniques. The eNNPS was measured at two isodose conditions for two phantoms using established techniques. The scatter was measured for two phantoms using an established beam stop method. All measurements were also taken at two different magnifications with two phantoms. A geometrical phantom was used for comparison with prior results for CXR although the results for an anatomy free phantom are not expected to vary for BCI.Results: Stereo/BCI resulted in improved metrics compared to single view CXR. Results indicated that magnification can potentially improve the detection performance primarily due to the air gap which reduced scatter by ?20%. For both phantoms, at isodose, eDQE(0) for stereo/BCI was ?100 times higher than that for CXR. Magnification at isodose improved eDQE(0) by ?10 times for stereo/BCI. Increasing the dose did not improve eDQE. The detectability index for stereo/BCI was ?100 times better than single view CXR for all conditions. The detectability index was also not improved with increased dose.Conclusions: The findings indicate that stereo/BCI with magnification may improve detectability of subtle lung nodules compared to single view CXR. Results were improved with magnification for the smaller phantom but not for the larger phantom. The effective DQE and the detectability index did not improve with increasing dose.

  18. Free vibration analysis of multi-layer graphene nanoribbons incorporating interlayer shear effect via molecular dynamics simulations and nonlocal elasticity

    NASA Astrophysics Data System (ADS)

    Nazemnezhad, Reza; Hosseini-Hashemi, Shahrokh

    2014-09-01

    Free vibration of cantilever multi-layer graphene nanoribbons (MLGNRs) with interlayer shear effect is investigated using molecular dynamics simulations (MD) and nonlocal elasticity. Because of similarity of MLGNRs to sandwich structures, sandwich formulations are expressed in the nonlocal form. By comparing the first two frequencies of MLGNRs with various layers and lengths obtained using MD simulations with those of the nonlocal sandwich formulation; the nonlocal parameter is calibrated to match the results of two methods. The results reveal that the calibrated nonlocal parameter for predicting the second frequencies is dependent on the number of MLGNR layers, and it increases by increasing the number of layers.

  19. Electrokinetic probes for single-step screening of polyol stereoisomers: the virtues of ternary boronate ester complex formation.

    PubMed

    Kaiser, Claire; Segui-Lines, Giselle; D'Amaral, Jason C; Ptolemy, Adam S; Britz-McKibbin, Philip

    2008-01-21

    Electrokinetic probes based on the differential migration of ternary boronate ester complexes permit the selective analysis of micromolar levels of UV-transparent polyol stereoisomers in urine samples via dynamic complexation-capillary electrophoresis that is applicable to single-step screening of in-born errors of sugar metabolism, such as galactosemia. PMID:18399200

  20. Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part I: Acidbase equilibria and pH buffersx

    E-print Network

    Santiago, Juan G.

    ­base equilibria and pH buffersx Alexandre Persat, Robert D. Chambers and Juan G. Santiago* Received 1st April 2009 electrokinetics. We present elements of acid­base equilibrium reactions and derive rules for pH calculation for simple buffers. We also present a general formulation to calculate pH of more complex, arbitrary mixtures

  1. Resolving distinct conformations of spectrally similar silver-DNA nanoclusters using electrokinetic flows

    NASA Astrophysics Data System (ADS)

    Del Bonis-O'Donnell, Jackson; Fygenson, Deborah; Pennathur, Sumita

    2012-11-01

    Silver-DNA nanoclusters (Ag:DNA) are hybrid fluorescent macromolecules in which a silver superatom is stabilized by segments of single stranded DNA in aqueous solution. Recently, electrokinetic separations in microchannels have proven useful for measuring the size and charge of different Ag:DNA emitters stabilized by the same sequence of DNA. Small (50-100pL) fluorescent sample plugs are electrokinetically injected down a 30 mm long, 20 ?m deep silica channel in the presence of a buffered background-electrolyte. Fluorophores contained within the injected plug travel at different velocities and thus separate down the length of the channel due to their differences in electrophoretic mobility. Diffusion measurements are also performed in situ by watching the time evolution of a stationary fluorescent sample plug. In the current work, the above techniques are applied to Ag:DNA stabilized by different sequences of DNA designed to adopt similar structures: a 12 cytosine single-stranded loop. Microfluidic separation measurements reveal the presence of multiple, spectrally similar Ag:DNA for different sequences, distinguished by their electrophoretic mobilities. Our results show that both versions of the 12C hairpin motif produce multiple fluorescent species each with different.

  2. DNA Motion Induced by Electrokinetic Flow near an Au Coated Nanopore Surface as Voltage Controlled Gate

    PubMed Central

    Sugimoto, Manabu; Kato, Yuta; Ishida, Kentaro; Hyun, Changbae; Li, Jiali

    2014-01-01

    The diffusion and drift motion of ? DNA molecules on Au coated membrane surface near nanopores prior to their translocation through solid-state nanopores are investigated using fluorescence microscopy. With the capability of controlling electric potential at the Au surface as a gate voltage, Vgate, the motions of DNA molecules vary dramatically near the nanopores in our observations, presumably generated by electrokinetic flow. We carefully investigate theses DNA motions with different values of Vgate in order to alter the densities and polarities of counterions; which are expected to change the flow speed or direction, respectively. Depending on Vgate, our observations have revealed the critical distance from a nanopore for DNA molecules to be attracted or to be repelled, DNA’s anisotropic and unsteady drifting motions and accumulations of DNA molecules near the nanopore entrance. Further finite element method (FEM) numerical simulations indicate that the electrokinetic flow could explain these unusual DNA motions near metal collated gated nanopores qualitatively. Finally, we demonstrate the possibility to control the speed and direction of DNA motion near or through a nanopore, for example, recapturing a single DNA molecule multiple times with AC voltages on the Vgate. PMID:25611963

  3. Selecting enhancing solutions for electrokinetic remediation of dredged sediments polluted with fuel.

    PubMed

    Rozas, F; Castellote, M

    2015-03-15

    In this paper a procedure for selecting the enhancing solutions in electrokinetic remediation experiments is proposed. For this purpose, dredged marine sediment was contaminated with fuel, and a total of 22 different experimental conditions were tested, analysing the influence of different enhancing solutions by using three commercial non-ionic surfactants, one bio-surfactant, one chelating agent, and one weak acid. Characterisation, microelectrophoretic and electrokinetic remediation trials were carried out. The results are explained on the basis of the interactions between the fuel, the enhancing electrolytes and the matrix. For one specific system, the electrophoretic zeta potential, (?), of the contaminated matrix in the solution was found to be related to the electroosmotic averaged ? in the experiment and not to the efficiency in the extraction. This later was correlated to a parameter accounting for both contributions, the contaminant and the enhancing solution, calculated on the basis of differences in the electrophoretic ? in different conditions which has allowed to propose a methodology for selection of enhancing solutions. PMID:25559497

  4. Monolayers of poly-L-lysine on mica--Electrokinetic characteristics.

    PubMed

    Morga, Maria; Adamczyk, Zbigniew; Gödrich, Sebastian; O?wieja, Magdalena; Papastavrou, Georg

    2015-10-15

    Physicochemical properties of poly-l-lysine and its monolayers on mica were thoroughly investigated by dynamic light scattering, electrokinetic methods and atomic force microscopy. The hydrodynamic diameter of PLL was equal to 25.5 nm within a wide range of pH and ionic strength. The electrophoretic measurements revealed that the molecules are positively charged for pH<10.5. By exploiting the electrophoretic mobility data, theelectrokinetic charge on the PLL molecules and their zeta potential were calculated. PLL monolayers of controlled coverage were deposited on mica under diffusion-controlled conditions by varying PLL bulk concentration and adsorption time. The electrokinetic characteristics of the monolayers were acquired in situ via streaming potential measurements. These studies allowed to uniquely determine the zeta potential of the monolayers as a function of pH and ionic strength. In this way the isoelectric point of the monolayers can be determined in a more convenient way compared to bulk measurements disturbed by the PLL molecule interactions. The stability of the monolayers under flow conditions was quantitatively evaluated via streaming potential measurements. The adsorption constant and the binding energy depth of PLL molecules were determined for different ionic strengths. These parameters indicate that the PLL monolayers remain stable over prolonged times. PMID:26115031

  5. Pore-scale dispersion in electrokinetic flow through a random sphere packing.

    PubMed

    Hlushkou, Dzmitry; Khirevich, Siarhei; Apanasovich, Vladimir; Seidel-Morgenstern, Andreas; Tallarek, Ulrich

    2007-01-01

    The three-dimensional velocity field and corresponding hydrodynamic dispersion in electrokinetic flow through a random bulk packing of impermeable, nonconducting spheres are studied by quantitative numerical analysis. First, a fixed bed with interparticle porosity of 0.38 is generated using a parallel collective-rearrangement algorithm. Then, the interparticle velocity field is calculated using the lattice-Boltzmann (LB) method, and a random-walk particle-tracking method is finally employed to model advection-diffusion of an inert tracer in the LB velocity field. We demonstrate that the pore-scale velocity profile for electroosmotic flow (EOF) is nonuniform even under most ideal conditions, including a negligible thickness of the electrical double layer compared to the mean pore size, a uniform distribution of the electrokinetic potential at the solid-liquid interface, and the absence of applied pressure gradients. This EOF dynamics is caused by a nonuniform distribution of the local electrical field strength in the sphere packing and engenders significant hydrodynamic dispersion compared to pluglike EOF through a single straight channel. Both transient and asymptotic dispersion behaviors are analyzed for EOF in the context of packing microstructure and are compared to pressure-driven flow in dependence of the average velocity through the bed. A better hydrodynamic performance of EOF originates in a still much smaller amplitude of velocity fluctuations on a mesoscopic scale (covering several particle diameters), as well as on the microscopic scale of an individual pore. PMID:17194128

  6. Removal of PAHs and pesticides from polluted soils by enhanced electrokinetic-Fenton treatment.

    PubMed

    Bocos, Elvira; Fernández-Costas, Carmen; Pazos, Marta; Sanromán, M Ángeles

    2015-04-01

    In this study, electrokinetic-Fenton treatment was used to remediate a soil polluted with PAHs and the pesticide pyrimethanil. Recently, this treatment has emerged as an interesting alternative to conventional soil treatments due to its peculiar advantages, namely the capability of treating fine and low-permeability materials, as well as that of achieving a high yield in the removals of salt content and inorganic and organic pollutants. In a standard electrokinetic-Fenton treatment, the maximum degradation of the pollutant load achieved was 67%, due to the precipitation of the metals near the cathode chamber that reduces the electro-osmotic flow of the system and thus the efficiency of the treatment. To overcome this problem, different complexing agents and pH control in the cathode chamber were evaluated to increase the electro-osmotic flux as well as to render easier the solubilization of the metal species present in the soil. Four complexing agents (ascorbic acid, citric acid, oxalic acid and ethylenediaminetetraacetic acid) in the Fenton-like treatment were evaluated. Results revealed the citric acid as the most suitable complexing agent. Thereby its efficiency was tested as pH controller by flushing it in the cathode chamber (pH 2 and 5). For the latter treatments, near total degradation was achieved after 27 d. Finally, phytotoxicity tests for polluted and treated samples were carried out. The high germination levels of the soil treated under enhanced conditions concluded that nearly complete restoration was achieved. PMID:25577698

  7. A production-inventory model with permissible delay incorporating learning effect in random planning horizon using genetic algorithm

    NASA Astrophysics Data System (ADS)

    Kar, Mohuya B.; Bera, Shankar; Das, Debasis; Kar, Samarjit

    2015-10-01

    This paper presents a production-inventory model for deteriorating items with stock-dependent demand under inflation in a random planning horizon. The supplier offers the retailer fully permissible delay in payment. It is assumed that the time horizon of the business period is random in nature and follows exponential distribution with a known mean. Here learning effect is also introduced for the production cost and setup cost. The model is formulated as profit maximization problem with respect to the retailer and solved with the help of genetic algorithm (GA) and PSO. Moreover, the convergence of two methods—GA and PSO—is studied against generation numbers and it is seen that GA converges rapidly than PSO. The optimum results from methods are compared both numerically and graphically. It is observed that the performance of GA is marginally better than PSO. We have provided some numerical examples and some sensitivity analyses to illustrate the model.

  8. Polymer/clay/wood nanocomposites: The effect of incorporation of nanoclay into the wood/polymer composites

    NASA Astrophysics Data System (ADS)

    Hetzer, Max E.

    Thermoplastic composites play an important role in our society. The uses of these composites range from cookware to components for the space shuttle. In recent years, researchers at Toyota developed numerous methods of preparation for composites made from olefins and inorganic fillers such as clay and calcium carbonate. Wood fibers have been used as reinforcing filler in polymer matrices for the past several decades. The advantages of using wood fibers as reinforcing fillers are: the low cost of the fibers (or flour), low density, and resistance to breakage. The disadvantage of using wood as a filler is the thermal instability of wood above 200 °C. The majority of thermoplastics exhibit melting points between 160 and 220 °C, which is in the range of thermal decomposition of wood. Nanoclay was first successfully used as a filler in polyolefin materials by the Toyota research team in early 90s. It was found that the addition of a small amount (< 5 wt.%) of nanoclay increased the mechanical properties of a Nylon-6 matrix dramatically. Since Nylon-6 is a hydrophilic material no compatibilizer was necessary to exfoliate the nanoclay. The use of compatibilizers such as maleic modified polyethylenes (MAPEs) is necessary upon addition of nanoclay to a hydrophobic polyolefin systems such polyethylene (PE) or polypropylene (PP). Few researchers have attempted to reinforce the polymer matrix via the use of the nanoclay for use as a matrix in wood/polymer composites. High molecular weight and low molecular weight MAPEs have been used to enhance the bonding between the nanoclay and the polymer matrix as well as between the wood flour and the polymer matrix. The effects of combinations of the high and low molecular weight MAPEs on the mechanical and thermal properties of polymer/clay nanocomposites (PCNs) and of wood/polymer/clay composites (WPCs) were investigated. The effects of adding nanoclay to wood/polymer systems on the mechanical and thermal properties of the composites were also investigated. A model based on the Halpin-Tsai model was developed that predicts the (Young's) modulus-temperature relationship of the composites based on discontinuous fillers. It was found that the molecular weight of the compatibilizer significantly affects the exfoliation/dispersion of the nanoclay within the polymer matrix. A compatibilizer containing a high Mw fraction based on high density polyethylene (HDPE) and a low Mw fraction based on linear low density polyethylene (LLDPE) was found to be the most effective at enhancing the thermal and mechanical properties of PCNs and WPCs. A compatibilizer containing greater than 60 wt.% high Mw fraction resulted in a 30% increase of the modulus and a 15°C increase of the heat deflection temperature (HDT). The addition of the nanoclay had a detrimental effect on the moduli of PCNs and WPCs when a low Mw compatibilizer based on LLDPE was used. The moduli of these composites increased with increasing high Mw content of the compatibilizer and increasing nanoclay content. The addition of the nanoclay to wood/polymer composites resulted in an increased modulus of elasticity and HDT of these composites. The developed model quantitatively predicts the modulus-temperature relationship of the fiber containing composites. It was found that the modulus of the composites varies linearly with temperature and was highly dependent on the exfoliation of the nanoclay within the polymer matrix.

  9. Effects of fluorine incorporation on the properties of Ge p -MOS capacitors with HfTiON dielectric

    NASA Astrophysics Data System (ADS)

    Li, C. X.; Leung, C. H.; Lai, P. T.; Xu, J. P.

    2010-07-01

    In this work, Ge p-MOS capacitors with HfTiON gate dielectric were fabricated by sputtering method. Pre-deposition fluorine plasma treatment and post-deposition fluorine plasma annealing were used to improve the electrical and reliability properties of Ge p-MOS capacitors. Experimental results showed that both methods could improve the interface quality with lower interface-state density, less frequency dispersion, and also enhance the reliability properties with smaller increases of oxide charge and gate leakage after high-field stressing. Compared with pre-deposition fluorine-plasma treatment, post-deposition fluorine plasma annealing achieved higher quality of high- k/Ge interface such as lower interface-state density, higher dielectric constant and lower stress-induced gate leakage current. By XPS and AFM analyses, the improvements should be due to the passivation effects of fluorine on oxygen vacancies, dangling bonds and the dielectric surface.

  10. Effects of nitrogen incorporation in InSb{sub 1-x}N{sub x} grown using radio frequency plasma-assisted molecular beam epitaxy

    SciTech Connect

    Pham, H. T.; Yoon, S. F.; Tan, K. H.; Boning, D.

    2007-02-26

    InSb{sub 1-x}N{sub x} was grown by radio frequency plasma-assisted molecular beam epitaxy. The effect of nitrogen plasma power (200-500 W) and growth temperature (330-420 deg. C) on nitrogen incorporation was investigated. A combined analysis involving x-ray diffraction, x-ray photoelectron spectroscopy, and secondary ion mass spectroscopy measurements indicates that the dominant nitrogen defect is interstitial N-Sb. Increasing the plasma power resulted in increase in the interstitial N-Sb amount rather than the substitutional N{sub Sb} amount. For fixed plasma power, decreasing the growth temperature helped reduce the interstitial N-Sb defect. Under the experimental conditions, the average value of substitutional N is approximately 1.6%-2%.

  11. Enhanced photovoltaic effect in BiVO4 semiconductor by incorporation with an ultrathin BiFeO3 ferroelectric layer.

    PubMed

    Dong, Wen; Guo, Yiping; Guo, Bing; Li, Hua; Liu, Hezhou; Joel, Thia Weikang

    2013-08-14

    The photovoltaic effect of BiVO4 semiconductor was investigated by incorporating an ultrathin BiFeO3 ferroelectric layer. It is found that the ultrathin ferroelectric layer with strong self-polarization and high carrier density is desirable to enhance the photovoltaic effect and to manipulate the photovoltaic polarity of the semiconductors. The photovoltage increases by 5-fold to 1 V, and the photocurrent density increases by 2-fold to 140 ?A/cm(2), in which the photovoltage is the highest compared with the reported values in polycrystalline and epitaxial ferroelectric thin film solar cells. The mechanism for the observed effect is discussed on the basis of a polarization-induced Schottky-like barrier at the BiFeO3/fluorine doped tin oxide interface. Our work provides good guidance for fabrication of cost-effective semiconductor photovoltaic devices with high performance, and this kind of ultrathin ferroelectric film may also have promising applications in copper indium gallium selenide solar cell, dye-sensitized TiO2 solar cell, lighting emitting diode, and other photoelectron related devices. PMID:23865621

  12. Network meta-analysis incorporating randomized controlled trials and non-randomized comparative cohort studies for assessing the safety and effectiveness of medical treatments: challenges and opportunities.

    PubMed

    Cameron, Chris; Fireman, Bruce; Hutton, Brian; Clifford, Tammy; Coyle, Doug; Wells, George; Dormuth, Colin R; Platt, Robert; Toh, Sengwee

    2015-01-01

    Network meta-analysis is increasingly used to allow comparison of multiple treatment alternatives simultaneously, some of which may not have been compared directly in primary research studies. The majority of network meta-analyses published to date have incorporated data from randomized controlled trials (RCTs) only; however, inclusion of non-randomized studies may sometimes be considered. Non-randomized studies can complement RCTs or address some of their limitations, such as short follow-up time, small sample size, highly selected population, high cost, and ethical restrictions. In this paper, we discuss the challenges and opportunities of incorporating both RCTs and non-randomized comparative cohort studies into network meta-analysis for assessing the safety and effectiveness of medical treatments. Non-randomized studies with inadequate control of biases such as confounding may threaten the validity of the entire network meta-analysis. Therefore, identification and inclusion of non-randomized studies must balance their strengths with their limitations. Inclusion of both RCTs and non-randomized studies in network meta-analysis will likely increase in the future due to the growing need to assess multiple treatments simultaneously, the availability of higher quality non-randomized data and more valid methods, and the increased use of progressive licensing and product listing agreements requiring collection of data over the life cycle of medical products. Inappropriate inclusion of non-randomized studies could perpetuate the biases that are unknown, unmeasured, or uncontrolled. However, thoughtful integration of randomized and non-randomized studies may offer opportunities to provide more timely, comprehensive, and generalizable evidence about the comparative safety and effectiveness of medical treatments. PMID:26537988

  13. Effect of incorporation of silane in the bonding agent on the repair potential of machinable esthetic blocks

    PubMed Central

    Zaghloul, Hanaa; Elkassas, Dina Wafik; Haridy, Mohamed Fouad

    2014-01-01

    Objective: To investigate the repair potential of CAD/CAM (computer-aided design/computer-aided manufacturing) ceramic and composite blocks using a silane-containing bonding agent with different repair protocols. Materials and Methods: Twenty-four discs were constructed from CAD/CAM ceramic and composite blocks. The discs were divided into six groups according to surface pre-treatment employed; GI: Diamond stone roughening (SR), GII: SR+ silanization (SR+S), GIII: Hydrofluoric acid etching (HF), GIV: HF+ silanization (HF+S), GV: Silica coating (SC), GVI: SC+ silanization (SC+S). Silane-containing bonding agent (Single Bond Universal adhesive, 3M ESPE) was applied to the pre-treated discs. Prior to light curing, irises were cut from tygon tubes (internal diameter = 0.8 mm and height = 0.5 mm) and mounted on each treated surface. Nanofilled resin composite (Filtek Z350XT, 3M ESPE) was packed into the cylinder lumen and light-cured (n = 10). The specimens were subjected to microshear bond strength testing (?-SBS) using universal testing machine. Failure modes of the fractured specimens were analyzed using field emission scanning electron microscope (FESEM). Eight representative discs were prepared to analyze the effect of surface treatments on surface topography using FESEM. ?-SBS results were analyzed using ANOVA and Tukeys post-hoc test. Results: Three-way ANOVA results showed that the materials, surface pre-treatment protocols, and silanization step had a statistically significant effect on the mean ?-SBS values at P ? 0.001. For ceramic discs, the groups were ranked; GIV (24.45 ± 7.35)> GVI ((20.18 ± 2.84)> GV (7.14 ± 14)= GII (6.72 ± 1.91)=GI (6.34 ± 2.21)=GIII (5.72 ± 2.18). For composite discs, groups were ranked; GI (24.98 ± 7.69)=GVI (24.84 ± 7.00) >GII (15.85 ± 5.29) =GV (14.65 ± 4.5)= GIV (14.24 ± 2.95)? GIII ((9.37 ± 2.78). Conclusion: The additional silanization step cannot be omitted if the repair protocol comprises of either hydrofluoric acid etching or silica coating for both CAD/CAM esthetic restorative materials. However, this step can be suppressed by using silane-containing adhesive with diamond stone roughened repair protocol. PMID:24966745

  14. Effect of Al incorporation on the structural, morphological, optoelectronic and transport properties of PbS thin films

    NASA Astrophysics Data System (ADS)

    Preetha, K. C.; Remadevi, T. L.

    2012-11-01

    Doping of PbS thin films with different metal atoms produce considerable changes in structural and material properties that make them useful in the technology of thin film devices. The goal of this work is to study the effects of doping on the structural, morphological, optoelectronic and transport properties of PbS thin films as a function of Al3+ concentration. Thin films of pure and Al doped PbS nanoparticles are prepared on soda lime glass substrates by chemical bath deposition technique. The Al content in aqueous solution is varied from 0 to 20 mg. XRD analysis of the films revealed significant enhancement in crystallinity and crystallite size up to an optimum concentration of doping. Films are polycrystalline with crystallite size 19-32 nm, having face centered cubic structure. The optical band gap energy exhibits a decreasing trend and is shifted from 2.41 to 1.34 eV with increasing Al content. The room temperature conductivity of the as-deposited PbS films is in the range of 0.78×10-8 to 0.67×10-6(? cm)-1 with a maximum for optimum Al content. The Al doped PbS thin film, which we synthesize with optimum Al concentration of 15 mg is found to be a most suitable material for solar control coating applications.

  15. Effect of enzymatic (thermostable ?-amylase) treatment on the physicochemical and antioxidant properties of extruded rice incorporated with soybean flour.

    PubMed

    Xu, Enbo; Wu, Zhengzong; Pan, Xiaowei; Long, Jie; Wang, Fang; Xu, Xueming; Jin, Zhengyu; Jiao, Aiquan

    2016-04-15

    In order to determine the effect of enzymatic extrusion on the physicochemical and antioxidant properties of rice/soybean mixture, different mass ratios (100/0, 95/5, 85/15, 70/30, 50/50 and 25/75%, w/w) were treated with thermostable ?-amylase. The reduced special mechanical energy and the enhanced product temperature were closely and regularly linked with the increase of soybean content. The bulk density and water solubility index increased, and the water absorption index and viscosities decreased remarkably after enzymatic extrusion, however, the modification caused by ?-amylase were dramatically eliminated with the increase of soybean content to ?50%. Moreover, the addition of enzyme exhibited an improvement of the total phenolic/flavonoid content (TPC/TFC) and antioxidant capacities compared to traditional extrusion. The TPC/TFC retention of extrudate (ratios of 85/15 and 70/30%) attained over 90%, but dramatically decreased (72.91 and 67.81%, respectively) with soybean added to 75%, probably due to the great reduction of starch substrate for enzymatic hydrolysis. PMID:26616931

  16. Effect of annealing on graphene incorporated poly-(3-hexylthiophene):CuInS{sub 2} photovoltaic device

    SciTech Connect

    Kumari, Anita Dixit, Shiv Kumar; Singh, Inderpreet

    2014-10-15

    The effect of thermal annealing on the power conversion efficiency (PCE) of poly(3-hexylthiophene) (P3HT):CuInS{sub 2} quantum dot:graphene photovoltaic device has been studied by analyzing optical characteristics of composite films and electrical characteristics of the device with structure indium tin oxide/poly[ethylene dioxythiophene]:poly[styrene sulfonate] (ITO/PEDOT:PSS)/P3HT:CIS:graphene/LiF/aluminum. It was observed that after annealing at 120°C for 15 min a typical device containing 0.005 % w/w of graphene shows the best performance with a PCE of 1.3%, an open-circuit voltage of 0.44V, a short-circuit current density of 7.6 mA/cm{sup 2}, and a fill factor of 0.39. It is observed that the thermal annealing considerably enhances the efficiency of solar cells. However, an annealing at higher temperature such as at 140°C results in a decrease in the device efficiency.

  17. Effect of photoperiod on the rate of 3H-thymidine incorporation of epididymal principal cells in adult Syrian hamsters

    SciTech Connect

    Johnson, L.; Bartke, A. )

    1991-04-01

    Photoperiod-induced cycles of gonadal regression and recrudescence in the Syrian hamster were used to determine if epididymal growth in adults involves mitotic activity of principal cells. In Experiment 1, the following groups of adult hamsters were examined: induced recrudescing (5L:19D (5 hr light and 19 hr dark) for 13 wk followed by 14L:10D for at least 3 wk), spontaneous recrudescing (5L:19D for 25 wk), and active gonadal state (14:10D). In Experiment 2, adult hamsters were divided into the following groups: induced recrudescing, active, and regressed (5L:19D for 16 wk). Hamsters received subcutaneous injections of 0.5 microCi 3H-thymidine/g body weight three times/wk for 3 wk. The epididymis was fixed in a glutaraldehyde followed by osmium, embedded in Epon 812, and sectioned at 1 micron. Slides were dipped in Kodak NTB-3 emulsion, exposed for 2 or 3 months, developed, and evaluated for isotopic labeling of principal and basal cell nuclei by scoring 500 to 1,000 nuclei. In Experiment 1, the percentages of labeled principal cell nuclei for the induced recrudescing, spontaneous recrudescing, and active groups were 26 {plus minus} 2%, 23 {plus minus} 5%, and 9 {plus minus} 1%, respectively. Considering the intermittent availability of 3H-thymidine during 21 days, this represents daily recruitment of 6.3%, 5.6%, and 2.2%, respectively. In Experiment 2, the percentages of labeled principal cell nuclei for induced recrudescing, active, and regressed groups were 12 {plus minus} 4%, 3 {plus minus} 1%, and 4 {plus minus} 1%, respectively. There was no effect of photoperiod on labeling pattern of basal cells (1.5 {plus minus} 0.6%, 1.2 {plus minus} 0.1%, 0.4 {plus minus} 0.1% for the three photoperiod groups, respectively).

  18. Electrokinetic and acoustic manipulations of colloidal and biological particles 

    E-print Network

    Park, Seungkyung

    2009-05-15

    Recent advances in microfluidic technologies have enabled integration of the functional units for biological and chemical analysis onto miniaturized chips, called Labon- a-Chip (LOC). However, the effective manipulation and control of colloidal...

  19. The effect of a polyurethane coating incorporating both a thrombin inhibitor and nitric oxide on hemocompatibility in extracorporeal circulation

    PubMed Central

    Major, Terry C.; Brisbois, Elizabeth J.; Jones, Anna M.; Zanetti, Margaux E.; Annich, Gail M.; Bartlett, Robert H.; Handa, Hitesh

    2014-01-01

    Nitric oxide (NO) releasing (NORel) materials have been extensively investigated to create localized increases in NO concentration by the proton driven diazeniumdiolate-containing polymer coatings and demonstrated to improve extracorporeal circulation (ECC) hemocompatibility. In this work, the NORel polymeric coating composed of a diazeniumdiolated dibutylhexanediamine (DBHD-N2O2)-containing hydrophobic Elast-eon™ (E2As) polyurethane was combined with a direct thrombin inhibitor, argatroban (AG), and evaluated in a 4 h rabbit thrombogenicity model without systemic anticoagulation. In addition, the immobilizing of argatroban to E2As polymer was achieved by either a polyethylene glycol-containing (PEGDI) or hexane methylene (HMDI) diisocyanate linker. The combined polymer film was coated on the inner walls of ECC circuits to yield significantly reduced ECC thrombus formation compared to argatroban alone ECC control after 4 h blood exposure (0.6 ± 0.1 AG/HMDI/NORel vs 1.7 ± 0.2 cm2 AG/HMDI control). Platelet count (2.8 ± 0.3 AG/HMDI/NORel vs 1.9 ± 0.1 × 108/ml AG/HMDI control) and plasma fibrinogen levels were preserved after 4 h blood exposure with both the NORel/argatroban combination and the AG/HMDI control group compared to baseline. Platelet function as measured by aggregometry remained near normal in both the AG/HMDI/NORel (63 ± 5%) and AG/HMDI control (58 ± 7%) groups after 3 h compared to baseline (77 ± 1%). Platelet P-selectin mean fluorescence intensity (MFI) as measured by flow cytometry also remained near baseline levels after 4 h on ECC to ex vivo collagen stimulation (16 ± 3 AG/HMDI/NORel vs 11 ± 2 MFI baseline). These results suggest that the combined AG/HMDI/NORel polymer coating preserves platelets in blood exposure to ECCs to a better degree than AG/PEGDI/NORel, NORel alone or AG alone. These combined antithrombin, NO-mediated antiplatelet effects were shown to improve thromboresistance of the AG/HMDI/NORel polymer-coated ECCs and move potential nonthrombogenic polymers closer to mimicking vascular endothelium. PMID:24927680

  20. The effect of a polyurethane coating incorporating both a thrombin inhibitor and nitric oxide on hemocompatibility in extracorporeal circulation.

    PubMed

    Major, Terry C; Brisbois, Elizabeth J; Jones, Anna M; Zanetti, Margaux E; Annich, Gail M; Bartlett, Robert H; Handa, Hitesh

    2014-08-01

    Nitric oxide (NO) releasing (NORel) materials have been extensively investigated to create localized increases in NO concentration by the proton driven diazeniumdiolate-containing polymer coatings and demonstrated to improve extracorporeal circulation (ECC) hemocompatibility. In this work, the NORel polymeric coating composed of a diazeniumdiolated dibutylhexanediamine (DBHD-N2O2)-containing hydrophobic Elast-eon™ (E2As) polyurethane was combined with a direct thrombin inhibitor, argatroban (AG), and evaluated in a 4 h rabbit thrombogenicity model without systemic anticoagulation. In addition, the immobilizing of argatroban to E2As polymer was achieved by either a polyethylene glycol-containing (PEGDI) or hexane methylene (HMDI) diisocyanate linker. The combined polymer film was coated on the inner walls of ECC circuits to yield significantly reduced ECC thrombus formation compared to argatroban alone ECC control after 4 h blood exposure (0.6 ± 0.1 AG/HMDI/NORel vs 1.7 ± 0.2 cm(2) AG/HMDI control). Platelet count (2.8 ± 0.3 AG/HMDI/NORel vs 1.9 ± 0.1 × 10(8)/ml AG/HMDI control) and plasma fibrinogen levels were preserved after 4 h blood exposure with both the NORel/argatroban combination and the AG/HMDI control group compared to baseline. Platelet function as measured by aggregometry remained near normal in both the AG/HMDI/NORel (63 ± 5%) and AG/HMDI control (58 ± 7%) groups after 3 h compared to baseline (77 ± 1%). Platelet P-selectin mean fluorescence intensity (MFI) as measured by flow cytometry also remained near baseline levels after 4 h on ECC to ex vivo collagen stimulation (16 ± 3 AG/HMDI/NORel vs 11 ± 2 MFI baseline). These results suggest that the combined AG/HMDI/NORel polymer coating preserves platelets in blood exposure to ECCs to a better degree than AG/PEGDI/NORel, NORel alone or AG alone. These combined antithrombin, NO-mediated antiplatelet effects were shown to improve thromboresistance of the AG/HMDI/NORel polymer-coated ECCs and move potential nonthrombogenic polymers closer to mimicking vascular endothelium. PMID:24927680

  1. Bayesian methodology incorporating expert judgment for ranking countermeasure effectiveness under uncertainty: example applied to at grade railroad crossings in Korea.

    PubMed

    Washington, Simon; Oh, Jutaek

    2006-03-01

    Transportation professionals are sometimes required to make difficult transportation safety investment decisions in the face of uncertainty. In particular, an engineer may be expected to choose among an array of technologies and/or countermeasures to remediate perceived safety problems when: (1) little information is known about the countermeasure effects on safety; (2) information is known but from different regions, states, or countries where a direct generalization may not be appropriate; (3) where the technologies and/or countermeasures are relatively untested, or (4) where costs prohibit the full and careful testing of each of the candidate countermeasures via before-after studies. The importance of an informed and well-considered decision based on the best possible engineering knowledge and information is imperative due to the potential impact on the numbers of human injuries and deaths that may result from these investments. This paper describes the formalization and application of a methodology to evaluate the safety benefit of countermeasures in the face of uncertainty. To illustrate the methodology, 18 countermeasures for improving safety of at grade railroad crossings (AGRXs) in the Republic of Korea are considered. Akin to "stated preference" methods in travel survey research, the methodology applies random selection and laws of large numbers to derive accident modification factor (AMF) densities from expert opinions. In a full Bayesian analysis framework, the collective opinions in the form of AMF densities (data likelihood) are combined with prior knowledge (AMF density priors) for the 18 countermeasures to obtain 'best' estimates of AMFs (AMF posterior credible intervals). The countermeasures are then compared and recommended based on the largest safety returns with minimum risk (uncertainty). To the author's knowledge the complete methodology is new and has not previously been applied or reported in the literature. The results demonstrate that the methodology is able to discern anticipated safety benefit differences across candidate countermeasures. For the 18 at grade railroad crossings considered in this analysis, it was found that the top three performing countermeasures for reducing crashes are in-vehicle warning systems, obstacle detection systems, and constant warning time systems. PMID:16288710

  2. Investigating electrokinetics application for in-situ inorganic oil field scale control

    NASA Astrophysics Data System (ADS)

    Hashaykeh, Manal A. I. Albadawi

    Oil well scale formation and deposition is an expensive problem and could be a nightmare for any production engineer if the rate of deposition is rapid as in the case of North Sea oil fields. Inorganic scales accumulate in surface and subsurface equipment causing a reduction in oil production and severe damage for production equipment. The major components of most oil field scale deposits are BaSO4, CaSO4 and SrSO4, which are formed due to incompatible mixing of reservoir formation water and sea water flooded in secondary enhanced oil recovery (EOR) processes. This work focuses on BaSO4 scale as it is one of the toughest scale components to be removed either by chemical means or mechanical means. Scale control methods usually involve complicated treatment using chemical dissolution methods as primary attempt and mechanical scrapping or jetting methods in case of failure of the chemical means. In this work, we devised a novel in-situ scale control method benefiting from the application of direct current (DC) which involves some of the electrokinetic (EK) phenomena. The applications of EK has been proved in our laboratories yielding high efficiency in capturing barium and separating it from sulfate before reaching the production well, thus preventing deposition in the production wellbore or wellbore formation. This objective was evaluated in our lab designed EK apparatus in three parts. In part-1, an 18.5 cm unconsolidated sand core was used which produced inconsistent results. This problem was overcome in part-2, where the porous media involved 46 cm consolidated sandcore. This also partly fulfilled the purpose of upscaling. In part-3, the porous media was extended to a 100 cm spatial distance between the injection and production wells. For all the experiments the reservoir models were made of 125 µm uniform sand particles and followed a final consolidation pressure of 30 psi. The EK-reservoir model contains 2 basic junctions; one of them injecting a 500 ppm SO4 2- solution, representing sulfate rich sea water and the other injecting a 500 ppm Ba2+ solution representing divalent cations rich in formation water and an outlet for water production. In part-1, there were 4 locations for the electrodes, while in part-2 and part-3 there were 5 electrode locations distributed along the spatial distance. Salinity of injection and formation water was varied within a range of 0 to 40,000 ppm. The flow rates of injection and formation water were constant throughout each experiment. In part-1 experiments, the flow rate was 1 ml/min, in part-2 this was increased to 2 ml/min, finally in part-3 this was further increased to 4.3 ml/min. 2 V/cm voltage gradient was applied for all of the experiments. On a real time basis the current, pressure, temperature, and pH of production water were all monitored. Finally, solid samples with scale deposits within were collected from different locations of the flow tubes. To be analyzed using an ICP-MS. The results have demonstrated up to 90% scale mitigation by the application of EK. In addition, there was pressure reduction in the flow tube, which could be justified due to chlorine gas generation at the locations sides creating a stimulation effect due to increased acidity. The observations from this study concluded that the application of EK will attribute to the production efficiency due to less scaling and reducing corrosion of surface equipment. This will attempt to demonstrate the world's first promising technique that could be used to replace expensive solutions which require well closure and incur production interruption loss. However, it is recommended that further extensive studies need to be done to confirm the results and finally design a pilot scale project to validate the lab work.

  3. Girls Incorporated of Pinellas

    E-print Network

    Meyers, Steven D.

    Girls Incorporated® of Pinellas 7700 61st Street, Pinellas Park, FL 33781 727.544.6230 · info@girlsinc-pinellas.org · girlsinc-pinellas.org Inspiring all girls to be strong, smart and bold AFTER SCHOOL PROGRAMS THAT COUNT! Girls Incorporated of Pinellas is a member of a national organization that provides a unique out

  4. Effect of epidermal growth factor (EGF) on (/sup 3/H)TdR incorporation into DNA in ad lib fed and fasted CD2F1 mice

    SciTech Connect

    Scheving, L.A.; Tsai, T.H.; Scheving, L.E.; Hoke, W.S.

    1987-03-01

    The effect of EGF on the incorporation of (/sup 3/H)TdR into DNA (DNA synthesis) was determined in the esophagus, liver, pancreas, and kidney in mice standardized to 12 hours (hr) of light alternating with 12 hr of darkness. A question asked was whether intraperitoneally administered EGF could alter the circadian patterns of DNA synthesis in these organs. The most marked effects of EGF were: an increase in DNA synthesis but only after a specific duration of time after treatment, ranging from 8 to 23 hr, which differed for each tissue, a similarity in the response of the esophagus in both ad lib fed and fasted mice, but not in the response of the liver, where the stimulatory effect of EGF observed in fed mice was dramatically reduced in fasted ones, and an advance in the phasing of the circadian rhythm in DNA synthesis of the esophagus by about 12 hr. In addition, no sex differences in fasted animals were found under the conditions of this study.

  5. Experimental evidence for kinetic effects on B/Ca in synthetic calcite: Implications for potential B(OH)4- and B(OH)3 incorporation

    NASA Astrophysics Data System (ADS)

    Uchikawa, Joji; Penman, Donald E.; Zachos, James C.; Zeebe, Richard E.

    2015-02-01

    The boron to calcium ratio (B/Ca) in biogenic CaCO3 is being increasingly utilized as a proxy for past ocean carbonate chemistry. However, B/Ca of cultured and core-top foraminifers show dependence on multiple physicochemical seawater properties and only a few of those have been inorganically tested for their impacts. Accordingly, our understanding of the controls on foraminiferal B/Ca and thus how to interpret B/Ca in fossil shells is incomplete. To gain a clearer understanding of the B incorporation mechanism, we performed inorganic calcite precipitation experiments using a pH-stat system. As previously reported, we confirm that B/Ca in calcite increases with both fluid pH and total B concentration (denoted as [BT], where [BT] = [B(OH)3] + [B(OH)4-]). We provide the first evidence that B/Ca also increases with the concentration of total dissolved inorganic carbon (DIC) and calcium ion. With the exception of the [BT] experiments, these chemical manipulations were accompanied by an increase in calcite saturation, and accordingly precipitation rate (denoted as R). But when pH and [Ca2+] were jointly varied at a fixed saturation level to maintain relatively constant R at different pH and [Ca2+] combinations, B/Ca was insensitive to both pH and [Ca2+] changes. These experimental results unequivocally suggest kinetic effects related to R on B/Ca. Furthermore, with a suite of chemical manipulations we found that the B/Ca variability is explicable by just R and the [BT]/[DIC] ratio in the parent fluids. This observation was particularly robust for relatively rapidly precipitated samples, whereas for relatively slowly precipitated samples, it was somewhat ambiguous whether the [BT]/[DIC] or [B(OH)4-]/[HCO3-] ratio provides a better fit to the experimental data. Nonetheless, our experimental results can be considered as indirect evidence for incorporation of both B(OH)4- and B(OH)3 into calcite. We propose a simple mathematical expression to describe the mode of B incorporation into synthetic calcite that depends only on the fluid [BT]/[DIC] ratio and the precipitation rate R. This novel finding has important implications for future calibrations and applications of the B/Ca proxy as well as the ?11B paleo-pH proxy.

  6. Combined use of a transformed red mud reactive barrier and electrokinetics for remediation of Cr/As contaminated soil.

    PubMed

    Cappai, G; De Gioannis, G; Muntoni, A; Spiga, D; Zijlstra, J J P

    2012-01-01

    A reactive barrier (RB) of transformed red mud (TRM), a by-product of the refinement of bauxite in alumina production, was placed adjacent to the anode of an electrokinetic (EK) system with the aim of enhancing removal of chromium or arsenic, added singly to a low permeability clayey soil, and favouring entrapment. The innovative study focused on evaluation of the synergic interaction between the EK system and the RB, and of the efficiency when compared to traditional EK remediation (control tests). The results obtained underlined the successful outcome of treatment of the Cr(VI)-contaminated soil. In presence of the TRM RB, 19.4% wt. of total Cr content was detected in the anolyte and 20.6% wt. trapped in the anodic RB after 6d, versus 6.6% wt. in the anolyte and 8.8% wt. in the soil adjacent to the anode following the control run without RB. On increasing duration of treatment up to 12d, 60.8% wt. of total initial Cr was found in the anolyte and 25.5% wt. trapped in the RB, versus 9.1% wt. and 5.3% wt., respectively, after a control run of the same duration. Finally, on increasing the mass of TRM in the RB, 60.6% wt. of initial Cr content was found to have accumulated in the RB, with Cr being completely absent from the anodic chamber. Conversely, combined treatment was much less effective on As contaminated soil, at least under the operative conditions applied. Low initial As concentration and interference with iron oxides in the soil were likely the reasons underlying low efficiency while attempting As decontamination. PMID:22119416

  7. Effect of Na Incorporation on the Growth and Properties of CdTe/CdS Devices OF CdTe/CdS DEVICES

    SciTech Connect

    Dhere, R.; Ramanathan, K.; Keane, J.; Zhou, J.; Moutinho, H.; Asher, S.; Noufi, R.

    2005-02-01

    Sodium is known to enhance p-type doping in copper indium diselenide (CIS)-based devices fabricated on soda-lime glass substrates, and similar amounts of Na are present in commercial cadmium telluride (CdTe) devices. We present the results on the effects of Na incorporation on the properties of CdTe/CdS solar cells prepared on borosilicate glass substrates. A NaF layer 10 to 30 nm thick was incorporated at either the CdS/CdTe interface or on the CdTe surface, as a source of Na. CdTe layers were deposited by close-spaced sublimation at substrate temperatures from 425 C (LT) to 620 C (HT), followed by heat-treatment in the presence of CdCl2 vapor. Atomic force microscopy analysis showed that the samples with NaF at the CdS/CdTe interface deposited in He ambient have larger grains with a sub-grain structure that disappears after CdCl2 heat treatment accompanied by an increase in grain size. Samples deposited in O2 ambient have smaller grains without a sub-grain structure. For samples with NaF deposited on the CdTe surface, LT samples with CdCl2 heat treatment showed a morphology similar to samples without NaF layers; but samples heat-treated in He ambient at 500 C prior to CdCl2 treatment showed a different microstructure with platelets on the surface.

  8. Electrokinetics Label-Free Attomolar Detection of Proteins Using

    E-print Network

    Gong, Jian Ru

    . Electrically addres- sable silicon nanowire field-effect transistors and electrodes for electroki- netic transport are integrated onto a common sensor chip platform, and the nanowire devices are subsequently functionalized with receptors for selective biomarker detection. Nanowire devices modified with monoclonal

  9. Glucocorticoid effect on melphalan cytotoxicity, cell-cycle position, cell size, and (/sup 3/H)uridine incorporation in one of three human melanoma cell lines

    SciTech Connect

    Benckhuijsen, C.; Osman, A.M.; Hillebrand, M.J.; Smets, L.A.

    1987-09-15

    Three human melanoma cell lines of known content of specific glucocorticoid-binding sites were studied for colony formation after a microM dose of glucocorticoid combined with melphalan. In one of the three cell lines, M-5A, subcloned from M-5 (formerly designated RPMI 8322), the effect of combined treatment was markedly increased compared to that of melphalan even if the glucocorticoid was applied for 1 h only, 10 h before the melphalan. Semilogarithmic dose-effect plots for a reduction of final plating efficiency by glucocorticoid were curvilinear, according to a receptor-mediated process. The effects of glucocorticoid, melphalan, and their combination were linearized by bilogarithmic median-effect plotting which allowed the quantitation of a synergism which was more marked in case of glucocorticoid pretreatment, for 1 or 24 h, than on simultaneous exposure. According to sequential DNA per cell cytophotometry, melphalan abolished in M-5A a glucocorticoid-induced arrest in the G1 phase of the cell cycle. The cytotoxic synergism correlated with an apparent stimulation by glucocorticoid of the rate of acid-insoluble incorporation of (/sup 3/H)uridine and (/sup 14/C)leucine and an increase in cell size and protein content in M-5A cells but not in the other two cell lines. The way in which glucocorticoids induce an enhanced susceptibility to melphalan is not clear. Our results appear compatible with a hypothesis that chromatin in a transcriptionally activated state is more vulnerable to cytotoxic attack by an alkylating agent than under average conditions.

  10. Thermally driven electrokinetic energy conversion with liquid water microjets

    NASA Astrophysics Data System (ADS)

    Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; Saykally, Richard J.

    2015-11-01

    A goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.

  11. The electrokinetic behavior of calcium oxalate monohydrate in macromolecular solutions

    NASA Technical Reports Server (NTRS)

    Curreri, P. A.; Onoda, G. Y., Jr.; Finlayson, B.

    1988-01-01

    Electrophoretic mobilities were measured for calcium oxalate monohydrate (COM) in solutions containing macromolecules. Two mucopolysaccharides (sodium heparin and chrondroitin sulfate) and two proteins (positively charged lysozyme and negatively charged bovine serum albumin) were studied as adsorbates. The effects of pH, calcium oxalate surface charge (varied by calcium or oxalate ion activity), and citrate concentration were investigated. All four macromolecules showed evidence for chemical adsorption. The macromolecule concentrations needed for reversing the surface charge indicated that the mucopopolysacchrides have greater affinity for the COM surface than the proteins. The amount of proteins that can chemically adsorb appears to be limited to approximately one monomolecular layer. When the surface charge is high, an insufficient number of proteins can chemically adsorb to neutralize or reverse the surface charge. The remaining surface charge is balanced by proteins held near the surface by longer range electrostatic forces only. Citrate ions at high concentrations appear to compete effectively with the negative protein for surface sites but show no evidence for competing with the positively charged protein.

  12. BIODIVERSITY Incorporating sociocultural adaptive

    E-print Network

    BIODIVERSITY VIEWPOINT Incorporating sociocultural adaptive capacity in conservation hotspot's refinement of his biodiversity hotspot analysis (Myers et al., 2000) and the observation that human population density is 71% higher in hotspots than outside of them (Cincotta et al. 2000), conservation

  13. Alternating current electrokinetic properties of gold-coated microspheres.

    PubMed

    García-Sánchez, Pablo; Ren, Yukun; Arcenegui, Juan J; Morgan, Hywel; Ramos, Antonio

    2012-10-01

    We present dielectrophoresis (DEP) and electrorotation (ROT) measurements of gold-coated polystyrene microspheres as a function of frequency and for several electrolyte conductivities. Particle rotation was counterfield with a maximum rotation rate observed at a single characteristic frequency. Negative DEP was observed for frequencies lower than this characteristic frequency and positive DEP for signal frequencies higher than this. These experimental observations are in agreement with predictions for the force and torque on the induced dipole of a perfectly polarizable metal sphere. We present a theoretical model for this case, and good agreement is found for both ROT and DEP measurements if we take into account the viscous friction for a spherical particle near a wall. From the characteristic frequency for rotation, we obtain the capacitance of the electrical double layer at the electrolyte-particle interface. Remarkably, no effect of induced charge electroosmosis around the particles can be inferred from DEP measurements. PMID:22931290

  14. Resolving Anomalies in Predicting Electrokinetic Energy Conversion Efficiencies of Nanofluidic Devices.

    PubMed

    Majumder, Sagardip; Dhar, Jayabrata; Chakraborty, Suman

    2015-01-01

    We devise a new approach for capturing complex interfacial interactions over reduced length scales, towards predicting electrokinetic energy conversion efficiencies of nanofluidic devices. By embedding several aspects of intermolecular interactions in continuum based formalism, we show that our simple theory becomes capable of representing complex interconnections between electro-mechanics and hydrodynamics over reduced length scales. The predictions from our model are supported by reported experimental data, and are in excellent quantitative agreement with molecular dynamics simulations. The present model, thus, may be employed to rationalize the discrepancies between low energy conversion efficiencies of nanofluidic channels that have been realized from experiments, and the impractically high energy conversion efficiencies that have been routinely predicted by the existing theories. PMID:26437925

  15. Resolving Anomalies in Predicting Electrokinetic Energy Conversion Efficiencies of Nanofluidic Devices

    NASA Astrophysics Data System (ADS)

    Majumder, Sagardip; Dhar, Jayabrata; Chakraborty, Suman

    2015-10-01

    We devise a new approach for capturing complex interfacial interactions over reduced length scales, towards predicting electrokinetic energy conversion efficiencies of nanofluidic devices. By embedding several aspects of intermolecular interactions in continuum based formalism, we show that our simple theory becomes capable of representing complex interconnections between electro-mechanics and hydrodynamics over reduced length scales. The predictions from our model are supported by reported experimental data, and are in excellent quantitative agreement with molecular dynamics simulations. The present model, thus, may be employed to rationalize the discrepancies between low energy conversion efficiencies of nanofluidic channels that have been realized from experiments, and the impractically high energy conversion efficiencies that have been routinely predicted by the existing theories.

  16. Numerical modeling of surface reaction kinetics in electrokinetically actuated microfluidic devices.

    PubMed

    Sadeghi, Arman; Amini, Younes; Saidi, Mohammad Hassan; Chakraborty, Suman

    2014-08-01

    We outline a comprehensive numerical procedure for modeling of species transport and surface reaction kinetics in electrokinetically actuated microfluidic devices of rectangular cross section. Our results confirm the findings of previous simplified approaches that a concentration wave is created for sufficiently long microreactors. An analytical solution, developed for the wave propagation speed, shows that, when normalizing with the fluid mean velocity, it becomes a function of three parameters comprising the channel aspect ratio, the relative adsorption capacity, and the kinetic equilibrium constant. Our studies also reveal that the reactor geometry idealized as a slit, instead of a rectangular shape, gives rise to the underestimation of the saturation time. The extent of this underestimation increases by increasing the Damkohler number or decreasing the dimensionless Debye-Hückel parameter. Moreover, increasing the values of the Damkohler number, the dimensionless Debye-Hückel parameter, the relative adsorption capacity, and the velocity scale ratio results in lower saturation times. PMID:25064245

  17. Resolving Anomalies in Predicting Electrokinetic Energy Conversion Efficiencies of Nanofluidic Devices

    PubMed Central

    Majumder, Sagardip; Dhar, Jayabrata; Chakraborty, Suman

    2015-01-01

    We devise a new approach for capturing complex interfacial interactions over reduced length scales, towards predicting electrokinetic energy conversion efficiencies of nanofluidic devices. By embedding several aspects of intermolecular interactions in continuum based formalism, we show that our simple theory becomes capable of representing complex interconnections between electro-mechanics and hydrodynamics over reduced length scales. The predictions from our model are supported by reported experimental data, and are in excellent quantitative agreement with molecular dynamics simulations. The present model, thus, may be employed to rationalize the discrepancies between low energy conversion efficiencies of nanofluidic channels that have been realized from experiments, and the impractically high energy conversion efficiencies that have been routinely predicted by the existing theories. PMID:26437925

  18. Biomedical Evaluation of Cortisol, Cortisone, and Corticosterone along with Testosterone and Epitestosterone Applying Micellar Electrokinetic Chromatography

    PubMed Central

    B?czek, Tomasz; Ol?dzka, Ilona; Konieczna, Lucyna; Kowalski, Piotr; Plenis, Alina

    2012-01-01

    The validated micellar electrokinetic chromatography (MEKC) was proposed for the determination of five steroid hormones in human urine samples. That technique allowed for the separation and quantification of cortisol, cortisone, corticosterone, testosterone, and epitestosterone and was sensitive enough to detect low concentrations of these searched steroids in urine samples at the range of 2–300?ng/mL. The proposed MEKC technique with solid-phase extraction (SPE) procedure was simple, rapid, and has been successfully applied as a routine procedure to analyze steroids in human urine samples. The MEKC method offered a potential in clinical routine practice because of the short analysis time (8?min), low costs, and simultaneous analysis of five endogenous hormones. Due to its simplicity, speed, accuracy, and high recovery, the proposed method could offer a tool to determine steroid hormones as potential biomarkers in biomedical investigations, what was additionally revealed with healthy volunteers. PMID:22536129

  19. Capillary electrokinetic separations with optical detection. Technical progress report, February 1, 1994--January 31, 1995

    SciTech Connect

    Sepaniak, M.J.

    1995-05-01

    This multifarious research program is dedicated to the development of capillary electrokinetic separation techniques and associated optical methods of detection. Currently, research is directed at three general objectives. First, fundamental studies of pertinent separation and band broadening mechanisms are being conducted, with the emphasis on achieving rapid separations and understanding separation systems that include highly-ordered assemblies as running buffer additives. Second, instrumentation and methodologies associated with these capillary separation techniques are being advanced. Third, applications of these separation and detection systems should fill current voids in the capabilities of capillary separation techniques. In particular, it should be possible to perform rapid, highly efficient, and selective separations of hydrophobic compounds (e.g., higher MW polycyclic aromatic hydrocarbons (PAHs) and fullerenes), certain optical isomers, DNA fragments, and various pollutants including certain heavy metals.

  20. Computational simulation of microfluidics, electrokinetics, and particle transport in biological MEMS devices

    NASA Astrophysics Data System (ADS)

    Giridharan, M. G.; Krishnamoorthy, Soumya; Krishnan, Anantha

    1999-03-01

    Biological MEMS devices are being developed for applications in collection, monitoring, diagnostics and drug delivery. The objective of this work is to develop a simulation tool for the design, analysis and optimization of these devices. Simulations of biological MEMS devices are challenging due to the non-Newtonian behavior of biological fluids, coupling of flow with electric fields in electrophoretic separations, transport of non-homogeneous cellular structures and mixing between Newtonian and non-Newtonian fluids. This paper presents Computational Fluid Dynamic (CFD) simulations of biological fluid flow, mixing, electro-kinetics and transport of particles in microfluidic systems. A commercial CFD code, CFD-ACE+, that solves the full Navier-Stokes equations using a finite-volume approach has been adapted to perform these simulations of biological MEMS devices. Model predictions are validated through comparisons with experimental data.

  1. Electrokinetic Delivery of Single Fluorescent Biomolecules in Fluidic Nanochannels

    SciTech Connect

    Davis, Lloyd M; Canfield, Brian K; Li, Xiaoxuan; Hofmeister, William; Shen, Guoqing; Lescano, Isaac; Bomar, Bruce W; Wikswo, John P; Markov, Dmitry P; Samson, Philip C; Daniel, Claus; Sikorski, Zbigniew; Robinson, William N

    2008-01-01

    We describe the fabrication of sub-100-nanometer-sized channels in a fused silica lab-on-a-chip device and experiments that demonstrate detection of single fluorescently labeled proteins in buffer solution within the device with high signal and low background. The fluorescent biomolecules are transported along the length of the nanochannels by electrophoresis and/or electro-osmosis until they pass into a two-focus laser irradiation zone. Pulse-interleaved excitation and time-resolved single-photon detection with maximum-likelihood analysis enables the location of the biomolecule to be determined. Diffusional transport of the molecules is found to be slowed within the nanochannel, and this facilitates fluidic trapping and/or prolonged measurements on individual biomolecules. Our goal is to actively control the fluidic transport to achieve rapid delivery of each new biomolecule to the sensing zone, following the completion of measurements, or the photobleaching of the prior molecule. We have used computer simulations that include photophysical effects such as triplet crossing and photobleaching of the labels to design control algorithms, which are being implemented in a custom field-programmable-gate-array circuit for the active fluidic control.

  2. An electric stimulation system for electrokinetic particle manipulation in microfluidic devices

    NASA Astrophysics Data System (ADS)

    Lopez-de la Fuente, M. S.; Moncada-Hernandez, H.; Perez-Gonzalez, V. H.; Lapizco-Encinas, B. H.; Martinez-Chapa, S. O.

    2013-03-01

    Microfluidic devices have grown significantly in the number of applications. Microfabrication techniques have evolved considerably; however, electric stimulation systems for microdevices have not advanced at the same pace. Electric stimulation of micro-fluidic devices is an important element in particle manipulation research. A flexible stimulation instrument is desired to perform configurable, repeatable, automated, and reliable experiments by allowing users to select the stimulation parameters. The instrument presented here is a configurable and programmable stimulation system for electrokinetic-driven microfluidic devices; it consists of a processor, a memory system, and a user interface to deliver several types of waveforms and stimulation patterns. It has been designed to be a flexible, highly configurable, low power instrument capable of delivering sine, triangle, and sawtooth waveforms with one single frequency or two superimposed frequencies ranging from 0.01 Hz to 40 kHz, and an output voltage of up to 30 Vpp. A specific stimulation pattern can be delivered over a single time period or as a sequence of different signals for different time periods. This stimulation system can be applied as a research tool where manipulation of particles suspended in liquid media is involved, such as biology, medicine, environment, embryology, and genetics. This system has the potential to lead to new schemes for laboratory procedures by allowing application specific and user defined electric stimulation. The development of this device is a step towards portable and programmable instrumentation for electric stimulation on electrokinetic-based microfluidic devices, which are meant to be integrated with lab-on-a-chip devices.

  3. Comparison of the effects of central and peripheral aluminum administration on regional 2-deoxy-D-glucose incorporation in the rat brain

    SciTech Connect

    Lipman, J.J.; Tolchard, S. )

    1989-01-01

    Intracerebroventricular (ICV) Injection of aluminum tartrate (ALT 205.7 mcg) in the rat induces a progressive encephalopathy characterized by neurobehavioral derangements. The condition is associated with a reduced ability of cerebral synaptosomes to incorporate radiolabeled 2-Deoxy-D-glucose (2DG) in vitro. The present study surveyed and compared the in vivo regional cerebral glucose uptake (rCGlu) capacity of rats injected with ALT 7 or 14 days previously either by the ICV or intraperitoneal routes. ICV injection produces transient rCGlu depression in caudate-putamen, geniculate bodies and periaquaeductal gray, resolving by day 14. Thalamic nuclei exhibit depressed rCGlu by the 7th day undergoing further depression by day 14. The rCGlu of occipitoparietal cortices, normal at day 7, was increased by day 14. In contrast, peripheral aluminum administration produced transient rCGlu depression in olfactory bulbs, frontal and occipitoparietal cortices, nucleus accumbens and cerebellum, and transiently increased rCGlu in the geniculate nuclei. These effects, present by day 7, had resolved by day 14 when rCGlu has increased in the previously normal pontine nuclei and decreased in the previously normal hippocampus.

  4. Role of Surface Chemistry in Nanoscale Electrokinetic Transport

    NASA Astrophysics Data System (ADS)

    Atalay, Selcuk

    This dissertation work presents the efforts to study the electrofluidics phenomena, with a focus on surface charge properties in nanoscale systems with the potential applications in imaging, energy conversion, ultrafiltration, DNA analysis/sequencing, DNA and protein transport, drug delivery, biological/chemical agent detection and micro/nano chip sensors. Since the ion or molecular or particle transport and also liquid confinement in nano-structures are strongly dominated by the surface charge properties, in regards of the fundamental understanding of electrofluidics at nanoscale, we have used surface charge chemistry properties based on 2-pK charging mechanism. Using this mechanism, we theoretically and analytically showed the surface charge properties of silica nanoparticles as a function of their size, pH level and salt ionic strength of aqueous solution. For a fixed particle size, the magnitude of the surface charge typically increases with an increase in pH or background salt concentration. Furthermore, we investigated the surface charge properties of a charged dielectric nanoparticle and flat wall in electrostatic interactions. According to the theoretical results strong interactions cause a non-uniform surface charge density on the nanoparticle and the plate as a result of the enhancement of proton concentration in the gap between the particle and the plate. This effect increases with decreased separation distance (Kh). We moreover investigated the ion confinement inside the nanospaces and using a continuum model, we showed the proton enhancement in extended nanochannels. The proton enrichment at the center of the nanochannel is significant when the bulk pH is medium high and the salt concentration is relatively low. The results gathered are informative for the development of biomimetic nanofluidic apparatuses and the interpretation of relevant experimental data. Later, we have developed an analytical model for electroosmotic ion transport inside pH-regulated nanoslits and compared the results with the numerical study. We showed the influences of background salt concentration, pH level and the length of nanoslit on EOF velocity. The predictions show that the EOF velocity increases first and then decrease with background salt concentration increasing and the EOF velocity increases with pH level of aqueous solution.

  5. Capillary liquid chromatography using laser-based and mass spectrometric detection. [Capillary zone electrophoresis (CZE); micellar electrokinetic capillary kchromatography (MECC)

    SciTech Connect

    Sepaniak, M.J.; Cook, K.D.

    1992-01-01

    In the years following the 1986 seminal paper (J. Chromatogr. Sci., 24, 347-352) describing modern capillary zone electrophoresis (CZE), the prominence of capillary electrokinetic separation techniques has grown. A related electrochromatographic technique is micellar electrokinetic capillary chromatography (MECC). This report presents a brief synopsis of research efforts during the current 3-year period. In addition to a description of analytical separations-based research, results of efforts to develop and expand spectrometric detection for the techniques is reviewed. Laser fluorometric detection schemes have been successfully advanced. Mass spectrometric research was less fruitful, largely owing to personnel limitations. A regenerable fiber optic sensor was developed that can be used to remotely monitor chemical carcinogens, etc. (DLC)

  6. SIMS investigations into the effect of growth conditions on residual impurity and silicon incorporation in GaN and Al{sub x}Ga{sub 1{minus}x}N

    SciTech Connect

    Parish, G.; Keller, S.; Denbaars, S.P.; Mishra, U.K.

    2000-01-01

    The authors have investigated the effect of metal-organic chemical vapor deposition growth conditions on impurity incorporation in GaN and AlGaN. Secondary ion mass spectrometry depth profile analyses were performed on GaN and AlGaN wafers with multiple layers in which temperature, V/III ratio, growth rate, carrier gas, Al content, and Si doping were varied. Trends in oxygen, carbon, and silicon concentrations were studied. Similar trends were observed for both GaN and AlGaN. Growth temperature, composition and V/III ratio had the largest effect on impurity incorporation. Silicon and oxygen incorporation were less susceptible to growth conditions than that of carbon.

  7. Structural rearrangement of mesostructured silica nanoparticles incorporated with ZnO catalyst and its photoactivity: Effect of alkaline aqueous electrolyte concentration

    NASA Astrophysics Data System (ADS)

    Jusoh, N. W. C.; Jalil, A. A.; Triwahyono, S.; Karim, A. H.; Salleh, N. F.; Annuar, N. H. R.; Jaafar, N. F.; Firmansyah, M. L.; Mukti, R. R.; Ali, M. W.

    2015-03-01

    ZnO-incorporated mesostructured silica nanoparticles (MSN) catalysts (ZM) were prepared by the introduction of Zn ions into the framework of MSN via a simple electrochemical system in the presence of various concentrations of NH4OH aqueous solution. The physicochemical properties of the catalysts were studied by XRD, 29Si MAS NMR, nitrogen adsorption-desorption, FE-SEM, TEM, FTIR, and photoluminescence spectroscopy. Characterization results demonstrated that the alkaline aqueous electrolyte simply generated abundant silanol groups on the surface of the catalysts as a consequence of desilication to form the hierarchical-like structure of the MSN. Subsequent restructuring of the silica network by the creation of oxygen vacancies and formation of Si-O-Zn during the electrolysis, as well as formation of new Si-O-Si bonds during calcination seemed to be the main factors that enhanced the catalytic performance of photodecolorization of methyl orange. A ZM prepared in the presence of 1.0 M NH4OH (ZM-1.0) was determined to be the most effective catalyst. The catalyst displays a higher first-order kinetics rate of 3.87 × 10-1 h-1 than unsupported ZnO (1.13 × 10-1 h-1) that prepared under the same conditions in the absence of MSN. The experiment on effect of scavengers showed that hydroxyl radicals generated from the three main sources; reduced O2 at the conduction band, decomposed water at the valence band and irradiated H2O2 in the solution, are key factors that influenced the reaction. It is also noted that the recycled ZM-1.0 catalyst maintained its activity up to five runs without serious catalyst deactivation.

  8. Imidazolium-based ionic liquid-type surfactant as pseudostationary phase in micellar electrokinetic chromatography of highly hydrophilic urinary nucleosides.

    PubMed

    Rageh, Azza H; Pyell, Ute

    2013-11-01

    Ionic liquid (IL)-type surfactants have been shown to interact more strongly with polar compounds than traditionally used quaternary ammonium cationic surfactants. The aim of this study is to provide an alternative micellar electrokinetic chromatographic method (MEKC) for the analysis of urinary nucleosides in their ionic form at low surfactant concentration. This approach could overcome the use of high surfactant concentrations typically associated with the analysis of these highly hydrophilic metabolites as neutral species, which is frequently accompanied by high electric current, Joule heating and long analysis time. The investigated IL-type surfactant; 1-tetradecyl-3-methylimidazolium bromide (C14MImBr) is similar to the commonly employed cationic surfactant; tetradecyltrimethylammonium bromide (TTAB) but it provides a different separation selectivity. We employed C14MImBr micelles for the MEKC analysis of seven urinary nucleosides. The studied analytes possess a negative charge at pH 9.38 (exceptions are adenosine and cytidine which are neutral at this pH value). Borate imparts an additional negative charge to these compounds after complexation with the cis-diol functionality of the ribose unit, which in turn enables them to interact with the oppositely charged C14MImBr micelles via electrostatic (Coulomb) forces. The effect of the concentration of borate (the complexing, competing and buffering ion) on the effective electrophoretic mobilities and on the retention factors was investigated. The effective electrophoretic mobility data show that complexation between these nucleosides and borate occurs with high degree of complexation even at very low borate concentration (2.5 mmol L(-1) disodium tetraborate). In addition, we found that the retention factors are strongly dependent on the borate concentration being the highest when using the lowest borate concentration and they can be regulated by variation of either tetraborate concentration or the pH of the background electrolyte using only 20 mmol L(-1) C14MImBr. We confirmed also that the main mode of interaction between these analytes and the C14MImBr micelles is electrostatic interaction. Our experimental results reveal that the cationic surfactant C14MImBr exhibits superior selectivity and higher reproducibility relative to that of TTAB, which makes this surfactant a promising cationic surfactant for the MEKC separation of other hydrophilic polar analytes. PMID:24119753

  9. Electrokinetic Locomotion

    NASA Astrophysics Data System (ADS)

    Moran, Jeffrey Lawrence

    The past decade has seen the rapid development of synthetic particles capable of propelling themselves at the micro- and nanometer scale through aqueous media. Several groundbreaking experiments have shown these so-called "nanomotors" to be capable of performing several useful microscale tasks. However, alongside this progress, the need has arisen to understand the physical mechanisms governing their motion, as well as the limitations on their capabilities. Explanations of the propulsion mechanisms driving synthetic nanomotors are critical not only for providing insight into novel physical phenomena, but also to guide and inform the design and implementation of nanomotors and nanomachines. Bimetallic rods, 2 microns in length, were first shown to move autonomously using hydrogen peroxide fuel in 2004. Since then, a number of theories have been proposed to explain how these particles convert chemical energy in the hydrogen peroxide to kinetic energy of motion. The leading theory states that the rod functions as a short-circuited electrochemical cell, with electrochemical reactions occurring asymmetrically on its surface. These reactions are thought to generate an electric field, which propels the particle via electrophoresis. However, until now, this mechanism has not received a rigorous theoretical treatment as it applies to bimetallic rods, hindering the development of these particles for practical applications. The goals of this dissertation are (i) to understand physically the motion of self-propelling metallic particles with electrochemical surface reactions, and (ii) to characterize the limitations on the propulsion mechanism. To accomplish these goals, I construct a complete numerical model for the motors using the finite-element method. The model includes the coupled Poisson-Nernst-Planck-Stokes equations with Frumkin-corrected Butler-Volmer boundary conditions to represent the surface reactions. I devote special attention to the transport phenomena occurring in the interfacial layer near the particle/solution interface, which play a key role in the locomotion. The model enables one to understand how the rods' motion depends on the properties of their environment, such as hydrogen peroxide concentration, solution electrical conductivity, and solution viscosity. The numerical simulations are complemented with a scaling analysis based on the governing equations, which makes definite, verifiable predictions of these dependences. One of the most important trends that has been observed experimentally is the significant decrease in speed induced by adding sub-millimolar concentrations of inert electrolyte. It is important to understand the physical reasons for the electrolyte-induced speed decrease, in order to know whether it is fundamental to this propulsion mechanism, or if there is some feasible means to circumvent it. Successful completion of this research will result in an improved understanding of the capabilities, as well as the risks and limits of applicability, of the bimetallic nanomotors for applications in nanotechnology and nanomedicine. Potential applications of the rods include the targeted delivery of drugs in the human body, sensing of chemical impurities in drinking water, and as engines to drive fabrication of microscale structures.

  10. The effect of warm-ups incorporating different volumes of dynamic stretching on 10- and 20-m sprint performance in highly trained male athletes.

    PubMed

    Turki, Olfa; Chaouachi, Anis; Behm, David G; Chtara, Hichem; Chtara, Moktar; Bishop, David; Chamari, Karim; Amri, Mohamed

    2012-01-01

    Recently, athletes have transitioned from traditional static stretching during warm-ups to incorporating dynamic stretching routines. However, the optimal volume of dynamic drills is yet to be identified. The aim of this repeated-measures study was to examine varying volumes (1, 2, and 3 sets) of active dynamic stretching (ADS) in a warm-up on 10- and 20-m sprint performance. With a within-subject design, 16 highly trained male participants (age: 20.9 ± 1.3 years; height: 179.7 ± 5.7 cm; body mass: 72.7 ± 7.9 kg; % body fat: 10.9 ± 2.4) completed a 5-minute general running warm-up before performing 3 preintervention measures of 10- to 20-m sprint. The interventions included 1, 2, and 3 sets of active dynamic stretches of the lower-body musculature (gastrocnemius, gluteals, hamstrings, quadriceps, and hip flexors) performed approximately 14 times for each exercise while walking (ADS1, ADS2, and ADS3). The active dynamic warm-ups were randomly allocated before performing a sprint-specific warm-up. Five minutes separated the end of the warm-up and the 3 postintervention measures of 10- to 20-m sprints. There were no significant time, condition, and interaction effects over the 10-m sprint time. For the 0- to 20-m sprint time, a significant main effect for the pre-post measurement (F = 10.81; p < 0.002), the dynamic stretching condition (F = 6.23; p = 0.004) and an interaction effect (F = 41.19; p = 0.0001) were observed. A significant decrease in sprint time (improvement in sprint performance) post-ADS1 (2.56%, p = 0.001) and post-ADS2 (2.61%, p = 0.001) was observed. Conversely, the results indicated a significant increase in sprint time (sprint performance impairment) post-ADS3 condition (2.58%, p = 0.001). Data indicate that performing 1-2 sets of 20 m of active dynamic stretches in a warm-up can enhance 20-m sprint performance. The results delineated that 3 sets of ADS repetitions could induce acute fatigue and impair sprint performance within 5 minutes of the warm-up. PMID:22158260

  11. SU-D-16A-03: A Radiation Pneumonitis Dose-Response Model Incorporating Non- Local Radiation-Induced Bystander Effect

    SciTech Connect

    Gordon, J; Snyder, K; Zhong, H; Chetty, I

    2014-06-01

    Purpose: Dose-response models that can reliably predict radiation pneumonitis (RP) to guide radiation therapy (RT) for lung cancer presently do not exist. A model is proposed that incorporates non-local radiationinduced bystander effect (RIBE). Methods: A single sigmoid response function, derived from published data for whole lung irradiation, relates RP probability to cumulative lung damage, regardless of fractionation scheme. Lung damage is assumed to be caused by direct local radiation damage, quantified via the linear-quadratic (LQ) model, and RIBE. Based on published data, RIBE is assumed to be activated when per-fraction dose rises above ?0.6 Gy, but is constant with dose above that threshold. Integral RIBE damage is assumed proportional to lung volume irradiated above ?0.6 Gy per fraction. Key model parameters include LQ ? and ?, and two RIBE parameters: the single-fraction probability ? of damage, and a proportionality parameter ? that relates the potential for RIBE damage to irradiated lung volume. All parameters are tentatively fitted from published data, the RIBE parameters from published RP rates for conventionally fractionated RT (CFRT) and stereotactic body RT (SBRT). Results: The model predicts dose-response curves that are consistent with clinical experience. It provides a tentative explanation for why V20 (33 fractions), V13 (20 fractions) and V5 (<10 fractions) are observed to be correlated with RP. It also provides a plausible explanation for the success of SBRT — RIBE damage increases with the number of fractions, so penalizes CFRT relative to SBRT. Conclusion: The proposed model is relatively simple, extrapolates from published data, plausibly explains several clinical observations, and produces dose-response curves that are consistent with clinical experience. While capable of elaboration, its ability to explain doseresponse experience with different fractionation schemes using a small number of assumptions and parameters is an advantage.

  12. Incorporating kinetic aspects of

    E-print Network

    Tutorial: Incorporating kinetic aspects of RF current drive in MHD simulation J. Pratt, E kinetic aspects of RF current drive in MHD simulation with a focus on ECCD stabilization of tearing modes J. Pratt, E. Westerhof Lorentz Workshop: Modeling Kinetic Aspects of Global MHD Modes 4 Dec 2013

  13. Web content incorporates user

    E-print Network

    Bove Jr., V. Michael

    Web content commonly incorporates user profile and tracking data to personalize information in response to various audience-related factors. C onsumers of Internet-mediated content increasingly expect a high degree of responsiveness in their online experiences. Responsive media sense and react usefully

  14. Robust analysis of the hydrophobic basic analytes loratadine and desloratadine in pharmaceutical preparations and biological fluids by sweeping-cyclodextrin-modified micellar electrokinetic chromatography.

    PubMed

    El-Awady, Mohamed; Belal, Fathalla; Pyell, Ute

    2013-09-27

    The analysis of hydrophobic basic analytes by micellar electrokinetic chromatography (MEKC) is usually challenging because of the tendency of these analytes to be adsorbed onto the inner capillary wall in addition to the difficulty to separate these compounds as they exhibit extremely high retention factors. A robust and reliable method for the simultaneous determination of loratadine (LOR) and its major metabolite desloratadine (DSL) is developed based on cyclodextrin-modified micellar electrokinetic chromatography (CD-MEKC) with acidic sample matrix and basic background electrolyte (BGE). The influence of the sample matrix on the reachable focusing efficiency is studied. It is shown that the application of a low pH sample solution mitigates problems associated with the low solubility of the hydrophobic basic analytes in aqueous solution while having advantages with regard to on-line focusing. Moreover, the use of a basic BGE reduces the adsorption of these analytes in the separation compartment. The separation of the studied analytes is achieved in less than 7min using a BGE consisting of 10mmolL(-1) disodium tetraborate buffer, pH 9.30 containing 40mmolL(-1) SDS and 20mmolL(-1) hydroxypropyl-?-CD while the sample solution is composed of 10mmolL(-1) phosphoric acid, pH 2.15. A full validation study of the developed method based on the pharmacopeial guidelines is performed. The method is successfully applied to the analysis of the studied drugs in tablets without interference of tablet additives as well as the analysis of spiked human urine without any sample pretreatment. Furthermore, DSL can be detected as an impurity in LOR bulk powder at the stated pharmacopeial limit (0.1%, w/w). The selectivity of the developed method allows the analysis of LOR and DSL in combination with the co-formulated drug pseudoephedrine. It is shown that in CD-MEKC with basic BGE, solute-wall interactions are effectively suppressed allowing the development of efficient and precise methods for the determination of hydrophobic basic analytes, whereas the use of a low pH sample solution has a positive impact on the attainable sweeping efficiency without compromising peak shape and resolution. PMID:23953618

  15. Origins of unintentional incorporation of gallium in InAlN layers during epitaxial growth, part II: Effects of underlying layers and growth chamber conditions

    NASA Astrophysics Data System (ADS)

    Kim, Jeomoh; Lochner, Zachary; Ji, Mi-Hee; Choi, Suk; Kim, Hee Jin; Kim, Jin Soo; Dupuis, Russell D.; Fischer, Alec M.; Juday, Reid; Huang, Yu; Li, Ti; Huang, Jingyi Y.; Ponce, Fernando A.; Ryou, Jae-Hyun

    2014-02-01

    We systematically study the origins and mechanisms for unintentional incorporation of gallium (Ga) during epitaxial growth of ternary InAlN thin-film layers. The origins of auto-incorporation of Ga have been investigated by using different underlying layers, regrown layers, and growth chamber conditions. It is shown that Ga-containing deposition on a wafer susceptor/carrier and on surrounding surfaces of uncooled parts in a growth chamber can be responsible for Ga in the InAl(Ga)N layers, while a GaN underlying layer below an InAl(Ga)N layer does not contribute to the auto-incorporation of Ga in the InAl(Ga)N layers. Especially, the Ga-containing deposition on the surfaces inside the chamber is believed to be the dominant source of auto-incorporated Ga, possibly due to the high vapor pressure of a liquid phase as a result of eutectic system formation between indium (In) and Ga. The pressure of liquid-phase Ga, pGa=~3.67×10-4 Torr, can be significant as compared to precursor partial pressures with pTMAl=3.7×10-4 Torr and pTMIn=2.4×10-5 Torr. In addition, magnesium (Mg) or magnesium precursor (Cp2Mg) in the growth chamber is shown to promote the auto-incorporation of Ga in the InAl(Ga)N layers.

  16. Efficient delivery to human lung fibroblasts (WI-38) of pirfenidone incorporated into liposomes modified with truncated basic fibroblast growth factor and its inhibitory effect on collagen synthesis in idiopathic pulmonary fibrosis.

    PubMed

    Togami, Kohei; Miyao, Aki; Miyakoshi, Kei; Kanehira, Yukimune; Tada, Hitoshi; Chono, Sumio

    2015-01-01

    In the present in vitro study, we assessed the delivery of pirfenidone incorporated into liposomes modified with truncated basic fibroblast growth factor (tbFGF) to lung fibroblasts and investigated the anti-fibrotic effect of the drug. The tbFGF peptide, KRTGQYKLC, was used to modify the surface of liposomes (tbFGF-liposomes). We used the thin-layer evaporation method, followed by sonication, to prepare tbFGF-liposomes containing pirfenidone. The cellular accumulation of tbFGF-liposomes was 1.7-fold greater than that of non-modified liposomes in WI-38 cells used as a model of lung fibroblasts. Confocal laser scanning microscopy showed that tbFGF-liposomes were widely localized in WI-38 cells. The inhibitory effects of pirfenidone incorporated into tbFGF-liposomes on transforming growth factor-?1 (TGF-?1)-induced collagen synthesis in WI-38 cells were evaluated by measuring the level of intracellular hydroxyproline, a major component of the protein collagen. Pirfenidone incorporated into tbFGF-liposomes at concentrations of 10, 30, and 100 µM significantly decreased the TGF-?1-induced hydroxyproline content in WI-38 cells. The anti-fibrotic effect of pirfenidone incorporated into tbFGF-liposomes was enhanced compared with that of pirfenidone solution. These results indicate that tbFGF-liposomes are a useful drug delivery system of anti-fibrotic drugs to lung fibroblasts for the treatment of idiopathic pulmonary fibrosis. PMID:25747986

  17. Mitigation of chloride and sulfate based corrosion in reinforced concrete via electrokinetic nanoparticle treatment

    NASA Astrophysics Data System (ADS)

    Kupwade-Patil, Kunal

    Concrete is a porous material which is susceptible to the migration of highly deleterious species such as chlorides and sulfates. Various external sources, including sea salt spray, direct seawater wetting, deicing salts and chlorides can contaminate reinforced concrete. Chlorides diffuse into the capillary pores of concrete and come into contact with the reinforcement. When chloride concentration at the reinforcement exceeds a threshold level it breaks down the passive oxide layer, leading to chloride induced corrosion. The application of electrokinetics using positively charged nanoparticles for corrosion protection in reinforced concrete structures is an emerging technology. This technique involves the principle of electrophoretic migration of nanoparticles to hinder chloride diffusion in the concrete. The return of chlorides is inhibited by the electrodeposited assembly of the nanoparticles at the reinforcement interface. This work examined the nanoparticle treatment impact on chloride and sulfate induced corrosion in concrete. Electrokinetic Nanoparticle (EN) treatments were conducted on reinforced cylindrical concrete, rectangular ASTM G109 specimens that simulate a bridge deck and full scale beam specimens. EN treatment to mitigate external sulfate attack in concrete was performed on cylindrical concrete specimens. Corrosion results indicated lower corrosion potentials and rates as compared to the untreated specimens. Scanning electron microscopy (SEM) showed a dense microstructure within the EN treated specimens. Chemical analysis (Raman spectroscopy, X ray-diffraction, and Fourier transform infrared spectroscopy FTIR) showed the presence of strength enhancing phases such as calcium aluminate hydrate (C-A-H) and increased amounts of calcium silicate hydrate (C-S-H) within the EN treated specimens. Strength and porosity results showed an increase in strength and a reduction in porosity among the EN treated specimens. EN treatment acted as a protective barrier that formed primarily at the reinforcement surface where it inhibited the ingress of chlorides. When applied to sulfate attack, EN treatment was found to extract sulfate ions. This treatment also reduced porosity and increased concrete strength. The strength increases were limited by the accumulation of spallation damage that was accrued during the sulfate exposure period of the work. This demonstrated that treatment for sulfate attack was best suited to early stages of degradation or as a preventive measure.

  18. Electrokinetic movement and biodegradation of 2,4-dichlorophenoxyacetic acid in silt soil.

    PubMed

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

    2001-07-01

    The coupling of electrokinetic movement of an organic contaminant, 2,4-dichlorophenoxyacetic acid (2,4-D), through soil and its biodegradation in situ has been demonstrated. In a first experiment, the direction and rate of movement of 2,4-D were determined using homogeneously contaminated soil (864 mg 2,4-D/kg dry weight soil) compacted into six individual compartments, 6 cm long, 3 cm wide, and 4 cm deep. Each compartment was bordered by a carbon felt anode and a stainless steel cathode. The application of a current density of 3.72 A/m(2) led to migration of 2,4-D towards the anode at a rate of approximately 4 cm/day. In a second experiment, electrokinetic movement and biodegradation were combined in situ. Sterilized silt soil contaminated with ring-labeled 14C-2,4-D (811 mg 2,4-D/kg dry weight soil) was compacted into a single soil compartment, 22 cm long, 7 cm wide, and 4 cm deep, in a 4.5 cm region adjacent to the cathode. The remainder of the compartment was filled with sterilized soil (to a total weight of 1,015 g). Burkholderia spp. RASC c2 (1.88 x 10(11) cells), a tetracycline-resistant bacterium with chromosomally encoded degradative genes for 2,4-D, was inoculated into the soil at a position 14-16 cm from the cathode. The reactor was placed within a sealed perspex box, with a constant air flow connected to sodium hydroxide traps. Under an applied current density of 0.89 A/m(2), the pollutant moved towards the bacteria. As it reached the inoculated region, its concentration decreased in the soil and 14CO2 was recovered in the traps. At the end of the experiment, 87.1% of radiolabel had been removed from the soil, 5.8% of which was recovered as 14CO2. A third, control, experiment showed a significant contrast in the absence of an electric current, where a slow rate of diffusion controlled the movement of both 2,4-D and bacteria in the soil and biodegradation occurred at the interface between the diffusing fronts. PMID:11353409

  19. Shell structure of natural rubber particles: evidence of chemical stratification by electrokinetics and cryo-TEM.

    PubMed

    Rochette, Christophe N; Crassous, Jérôme J; Drechsler, Markus; Gaboriaud, Fabien; Eloy, Marie; de Gaudemaris, Benoît; Duval, Jérôme F L

    2013-11-26

    The interfacial structure of natural rubber (NR) colloids is investigated by means of cryogenic transmission electron microscopy (cryo-TEM) and electrokinetics over a broad range of KNO3 electrolyte concentrations (4-300 mM) and pH values (1-8). The asymptotic plateau value reached by NR electrophoretic mobility (?) in the thin double layer limit supports the presence of a soft (ion- and water-permeable) polyelectrolytic type of layer located at the periphery of the NR particles. This property is confirmed by the analysis of the electron density profile obtained from cryo-TEM that evidences a ?2-4 nm thick corona surrounding the NR polyisoprene core. The dependence of ? on pH and salt concentration is further marked by a dramatic decrease of the point of zero electrophoretic mobility (PZM) from 3.6 to 0.8 with increasing electrolyte concentration in the range 4-300 mM. Using a recent theory for electrohydrodynamics of soft multilayered particles, this "anomalous" dependence of the PZM on electrolyte concentration is shown to be consistent with a radial organization of anionic and cationic groups across the peripheral NR structure. The NR electrokinetic response in the pH range 1-8 is indeed found to be equivalent to that of particles surrounded by a positively charged ?3.5 nm thick layer (mean dissociation pK ? 4.2) supporting a thin and negatively charged outermost layer (0.6 nm in thickness, pK ? 0.7). Altogether, the strong dependence of the PZM on electrolyte concentration suggests that the electrostatic properties of the outer peripheral region of the NR shell are mediated by lipidic residues protruding from a shell containing a significant amount of protein-like charges. This proposed NR shell interfacial structure questions previously reported NR representations according to which the shell consists of either a fully mixed lipid-protein layer, or a layer of phospholipids residing exclusively beneath an outer proteic film. PMID:24152085

  20. Zinc Incorporation Into Hydroxylapatite

    SciTech Connect

    Tang, Y.; Chappell, H; Dove, M; Reeder, R; Lee, Y

    2009-01-01

    By theoretical modeling and X-ray absorption spectroscopy, the local coordination structure of Zn incorporated into hydroxylapatite was examined. Density function theory (DFT) calculations show that Zn favors the Ca2 site over the Ca1 site, and favors tetrahedral coordination. X-ray absorption near edge structure (XANES) spectroscopy results suggest one dominant coordination environment for the incorporated Zn, and no evidence was observed for other Zn-containing phases. Extended X-ray absorption fine structure (EXAFS) fitting of the synthetic samples confirms that Zn occurs in tetrahedral coordination, with two P shells at 2.85-3.07 {angstrom}, and two higher Ca shells at 3.71-4.02 {angstrom}. These fit results are consistent with the most favored DFT model for Zn substitution in the Ca2 site.

  1. In vivo and in vitro effects of growth hormone on the incorporation of ( UC)leucine into protein of liver and muscle of the eel

    SciTech Connect

    Inui, Y.; Ishioka, H.

    1985-08-01

    In vivo administration of ovine GH (2 micrograms/g body wt) increased ( UC)leucine incorporation into protein of the liver, skeletal muscle, and opercular muscle of hypophysectomized eels. Addition of ovine GH into the medium slightly increased ( UC)leucine incorporation into protein of liver slices during 5 hr in vitro incubation, but did not affect protein synthesis from ( UC)leucine in opercular muscle. In vivo pretreatment with ovine GH 48 hr prior to tissue preparation clearly increased ( UC)leucine incorporation into protein of liver slices in vitro. However, no statistically significant change was observed for in vitro incorporation of ( UC)leucine into protein of opercular muscle of hypophysectomized eels which had been previously treated with ovine GH. These results indicate that ovine GH has a protein anabolic action in the liver and muscle of the eel and that compared to mammals a rather long lag period is needed to elicit such protein anabolic actions of GH in these animals.

  2. Hollow fiber based liquid-liquid-liquid microextraction combined with sweeping micellar electrokinetic chromatography for the sensitive determination of second-generation antidepressants in human fluids.

    PubMed

    Zhou, Xiaoqing; He, Man; Chen, Beibei; Hu, Bin

    2015-03-01

    An effective dual preconcentration method involving off-line hollow fiber liquid-liquid-liquid microextraction (HF-LLLME) and on-line sweeping micellar electrokinetic chromatography (sweeping-MEKC) was proposed for the determination of five second-generation antidepressants, including fluoxetine, sertraline, paroxetine, fluvoxamine and citalopram. In HF-LLLME, the analytes were extracted from the sample solution into phenetole impregnated in the pores of the hollow fiber and then back-extracted into 10 ?L 0.1 mol L(-1) HAc inside the hollow fiber. Then, the acceptor phase was spiked with 2.8 ?L isopropanol (IPA) and introduced into CE for sweeping. In the sweeping-MEKC process, five target analytes were separated in less than 15 min with a background electrolyte consisting of 76% (v/v) 50 mmol L(-1) citric acid (pH 2.2) containing 100 mmol L(-1) sodium dodecyl sulfate (SDS) and 24% (v/v) IPA. The hydrodynamic injection was performed at 50 mbar for 140 s. Under optimized conditions, the limits of detection were in the range of 0.40-1.55 ?g L(-1) with enrichment factors of 1897- to 5952-fold for target analytes, with a dynamic linear range of 0.6/5.0-200 ?g L(-1). The developed method demonstrated excellent clean-up ability and high enrichment factors and was successfully applied to the analysis of target analytes in human urine and plasma samples. PMID:25620069

  3. Effect of cerium incorporation into zirconia on the activity ofCu/ZrO2 for methanol synthesis via CO hydrogenation

    SciTech Connect

    Pokrovski, Konstantin A.; Rhodes, Michael D.; Bell, Alexis T.

    2005-08-24

    The effects of Ce incorporation into ZrO2 on the catalyticperformance of Cu/ZrO2 for the hydrogenation of CO have beeninvestigated. A Ce0.3Zr0.7O2 solid solution was synthesized by forcedhydrolysis at low pH. After calcination at 873 K, XRD and Ramanspectroscopy characterization indicated that the Ce0.3Zr0.7O2 had a t''crystal structure. 1.2 wt percent Cu/Ce0.3Zr0.7O2 exhibited H2consumption peaks at low temperature (<473 K) during H2-TPRindicating a significant fraction (~; 70 percent) of Ce4+ is reduced toCe3+. 1.2 wt percent Cu/Ce0.3Zr0.7O2 is 2.7 times more active formethanol synthesis than 1.2 wt percent Cu/m-ZrO2 at 3.0 MPa attemperatures between 473 and 523 K and exhibits a higher selectivity tomethanol. In-situ infrared spectroscopy shows that, analogous toCu/m-ZrO2, the primary surface species on Cu/Ce0.3Zr0.7O2 during COhydrogenation are formate and methoxide species. A shift in the bandposition of the bridged methoxide species indicated that some of thesegroups were bonded to both Zr4+ and Ce3+ cations. For both catalysts, therate-limiting step for methanol synthesis is the reductive elimination ofmethoxide species. The higher rate of methanol synthesis onCu/Ce0.3Zr0.7O2 relative to Cu/m-ZrO2 was primarily due to a ~; 2.4 timeshigher apparent rate constant, kapp, for methoxide hydrogenation, whichis attributed to the higher surface concentration of H atoms on theformer catalyst. The increased capacity of the Ce-containing catalyst isattributed to interactions of H atoms with Ce-O pairs present at thesurface of the oxide phase.

  4. A case of biliary stones and anastomotic biliary stricture after liver transplant treated with the rendez - vous technique and electrokinetic lithotritor

    PubMed Central

    Pisa, Marta Di; Traina, Mario; Miraglia, Roberto; Maruzzelli, Luigi; Volpes, Riccardo; Piazza, Salvatore; Luca, Angelo; Gridelli, Bruno

    2008-01-01

    The paper studies the combined radiologic and endoscopic approach (rendez vous technique) to the treatment of the biliary complications following liver transplant. The “rendez-vous” technique was used with an electrokinetic lithotripter, in the treatment of a biliary anastomotic stricture with multiple biliary stones in a patient who underwent orthotopic liver transplant. In this patient, endoscopic or percutaneous transhepatic management of the biliary complication failed. The combined approach, percutaneous transhepatic and endoscopic treatment (rendez-vous technique) with the use of an electrokinetic lithotritor, was used to solve the biliary stenosis and to remove the stones. Technical success, defined as disappearance of the biliary stenosis and stone removal, was obtained in just one session, which definitively solved the complications. The combined approach of percutaneous transhepatic and endoscopic (rendez-vous technique) treatment, in association with an electrokinetic lithotritor, is a safe and feasible alternative treatment, especially after the failure of endoscopic and/or percutaneous trans-hepatic isolated procedures. PMID:18473423

  5. Comparison of microstructures of microemulsion and swollen micelle in electrokinetic chromatography.

    PubMed

    Cao, Yuhua; Ni, Xinjiong; Sheng, Jianwei

    2011-05-01

    Recently, 1-butanol modified MEKC was proven to be similar to MEEKC in separation performance. In the present work, typical microemulsion containing 0.8% n-octane/3.3% SDS/6.6% 1-butanol/20 mM borax buffer and corresponding swollen micelle without n-octane were used to compare their microdroplet structures including hydrodynamic radius, electrokinetic potential ? and charge density at the hydrodynamic shear surface, as well as microenvironment polarity in the interior of the microdroplets. Three kinds of corticosteroids were separated with MEEKC and 1-butanol modified MEKC to assess their separation performances. The experiment results showed that both microstructure and separation performance in microemulsion and in swollen micelle systems were alike, no matter whether oil phase n-octane was present. The environment polarity in the core of swollen micelle was slightly higher than in the microemulsions, and both of them were higher than in n-octane medium. Furthermore, the influences of SDS and 1-butanol concentration on microstructures were measured in details. Increasing the amount of SDS, hydrodynamic radius decreased in microemulsion but increased in swollen micelle. On the contrary, ? and shear surface charge density changed in the reverse trends. With increment of 1-butanol concentration, the hydrodynamic radius increased dramatically in microemulsions, whereas decreased slightly in swollen micelle. Even though using n-octane as oil core was not a key factor, microemulsions and swollen micelle as pseudostationary phase in EKC should not be exactly the same. PMID:21439571

  6. Electrokinetic device for three-dimensional trapping of single fluorescent emitters

    NASA Astrophysics Data System (ADS)

    King, Jason K.; Canfield, Brian K.; Davis, Lloyd M.

    2013-03-01

    Trapping by use of actively controlled electric fields is a valuable tool for studies of single biological molecules and nanoparticles. Devices have been developed to trap in one and two dimensions, but these rely on physically constraining the molecule along one or more directions. However, behavior of trapped molecules may be perturbed due to high collision rates with walls. Here we report on the development of a three-dimensional (3D) electrokinetic trap to counteract Brownian motion. Two pairs of electrodes arranged in a crossed configuration on separate planes allow generation of an electric field of variable orientation and magnitude. A custom forward-illuminated microscope with astigmatism introduced to the tube lens is used to determine the nanoparticle's 3D position in real time. This device has demonstrated the capability to manipulate and confine single 40 nm fluorescent latex beads in glycerol-water solution. The use of an electron-multiplying CCD camera allows for faster detection rates (>100 Hz) and single-photon sensitivity. Characterization of particle motion and performance analysis of trapping methods is investigated. The use of alternative 3D detection methods is discussed, as well as applications to studies of single biomolecules and nanoparticles.

  7. Relevance of electrokinetic theory for "soft" particles to bacterial cells: implications for bacterial adhesion.

    PubMed

    de Kerchove, Alexis J; Elimelech, Menachem

    2005-07-01

    Bacterial cells and other biological particles carry charged macromolecules on their surface that form a "soft" ion-permeable layer. In this paper, we test the applicability of an electrokinetic theory for soft particles to characterize the electrophoretic mobility (EPM) and adhesion kinetics of bacterial cells. The theory allows the calculation of two parameters--the electrophoretic softness and the fixed charged density--that define the characteristics of the polyelectrolyte layer at the soft particle surface. The theory also allows the calculation of an outer-surface potential that may better predict the electrostatic interaction of soft particles with solid surfaces. To verify its relevance for bacterial cells, the theory was applied to EPM measurements of two well-characterized Escherichia coli K12 mutants having lipopolysaccharide (LPS) layers of different lengths and molecular compositions. Results showed that the obtained softness and fixed charge density were not directly related to the known characteristics of the LPS of the selected strains. Interaction energy profiles calculated from Derjaguin-Landau-Verwey-Overbeek (DLVO) theory were used to interpret bacterial deposition (adhesion) rates on a pure quartz surface. The outer surface potential failed to predict the low attachment efficiencies of the two bacterial strains. The lack of success in the application of the theory for soft particles to bacterial cells is attributed to chemical and physical heterogeneities of the polyelectrolyte layer at the cell surface. PMID:15982054

  8. A PDMS sample pretreatment microdevice to enable downstream electrokinetic manipulations in bovine serum

    NASA Astrophysics Data System (ADS)

    Abram, Timothy J.; Clague, David S.

    2010-02-01

    The notion of sample preconditioning, or pretreatment, as a micro-unit operation in a Lab on a Chip (LOC) system has yet to be realized in commercial practice. As is well known, Biomarker detection in complex, biological samples, such as blood, requires a series of pretreatment steps to enable detection of specific markers. On chip, such a process usually relies on "off-chip" sample pretreatment prior to "on-chip" analyte manipulations and detection. Presented in this paper is a PDMS, pretreatment chip based on the design of Oddy et al.1 with a view to enable a self-contained LOC platform. The chip was designed to directly manipulate the suspended species while adjusting fluid properties using buffer volumes less than 1 ml. Using previous literature related to capillary electrophoresis, a bench-scale pretreatment protocol was developed to tune specific fluidic parameters to an optimal range, namely pH, conductivity, and viscosity. A PDMS device was fabricated and used to combine a raw, bovine serum sample with specific buffer solutions. Off-chip electrodes were used to induce DC-electrokinetic micro-mixing of the target analyte in the mixing chamber, where a homogeneous analyte distribution was achieved in less than one second using an 800V DC pulse wave. Additionally, the desired solution viscosity and pH were achieved using less than 1 ml of buffer solution. Adjustment of sample conductivity, which is driven by sample fluid volume, remains an open area of research.

  9. Simultaneous Determination of Two Amino Bisphosphonates Drugs by Micellar Electrokinetic Chromatography.

    PubMed

    Wu, Di; Yang, Jiajia; Cai, Yuanli; Lin, Xia; Yan, Jin; Li, Hui

    2015-11-01

    A sensitive micellar electrokinetic chromatographic method with laser-induced fluorescence detection was developed for the determination of alendronate sodium (ALN) and pamidronate disodium (PAM) after derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole. The developed method was first used for the determination of ALN and PAM in pharmaceutical preparations. After optimization, baseline separation of the analytes could be obtained in <10 min in a running buffer composed of 10 mM sodium borate and 30 mM sodium dodecyl sulfate (pH 9.0) at a voltage of 15 kV with 25°C cartridge temperature and the samples were injected by pressure (3447.5 Pa × 3 s). The method has linearity range of 0.05-70 µg/mL for the analytes (correlation coefficients: 0.9995 and 0.9997), the detection limits were 4 and 10 ng/mL for ALN and PAM, respectively. In intraday precision experiment, the relative standard deviation (RSD) values for migration time were 0.30% (ALN) and 0.27% (PAM), and the RSD values for peak areas were 1.19% (ALN) and 1.32% (PAM). The ranges of recovery were 95.5-101.8 and 94.6-105.3% for ALN and PAM, respectively. This method is not only rapid and accurate but also has the potential to be used for the quality control in pharmaceutical preparations of the two drugs. PMID:26113636

  10. Potentiometric and electrokinetic signatures of iron(ii) interactions with (?,?)-Fe2O3.

    PubMed

    Toczyd?owska, Diana; K?dra-Królik, Karolina; Nejbert, Krzysztof; Preo?anin, Tajana; Rosso, Kevin M; Zarzycki, Piotr

    2015-09-30

    The electrochemical signatures of Fe(ii) interactions with iron(iii) oxides are poorly understood, despite their importance in controlling the amount of mobilized iron. Here, we report the potentiometric titration of ?,?-Fe2O3 oxides exposed to Fe(ii) ions. We monitored in situ surface and ? potentials, the ratio of mobilized ferric to ferrous, and the periodically analyzed nanoparticle crystal structure using X-ray diffraction. Electrokinetic potential reveals weak but still noticeable specific sorption of Fe(ii) to the oxide surface under acidic conditions, and pronounced adsorption under alkaline conditions that results in a surface potential reversal. By monitoring the aqueous iron(ii/iii) fraction, we found that the addition of Fe(ii) ions produces platinum electrode response consistent with the iron solubility-activity curve. Although, XRD analysis showed no evidence of ?-Fe2O3 transformations along the titration pathway despite iron cycling between aqueous and solid reservoirs, the magnetite formation cannot be ruled out. PMID:26384152

  11. Fabrication and validation of a multi-channel type microfluidic chip for electrokinetic streaming potential devices.

    PubMed

    Chun, Myung-Suk; Shim, Min Suk; Choi, Nak Won

    2006-02-01

    To elaborate on the applicability of the electrokinetic micro power generation, we designed and fabricated the silicon-glass as well as the PDMS-glass microfluidic chips with the unique features of a multi-channel. Besides miniaturizing the device, the key advantage of our microfluidic chip utilization lies in the reduction in water flow rate. Both a distributor and a collector taking the tapered duct geometry are positioned aiming the uniform distribution of water flow into all individual channels of the chip, in which several hundreds of single microchannels are assembled in parallel. A proper methodology is developed accompanying the deep reactive ion etching as well as the anodic bonding, and optimum process conditions necessary for hard and soft micromachining are presented. It has been shown experimentally and theoretically that the silicon-based microchannel leads to increasing streaming potential and higher external current compared to those of the PDMS-based one. A proper comparison between experimental results and theoretical computations allows justification of the validity of our novel devices. It is useful to recognize that a material inducing a higher magnitude of zeta potential has an advantage for obtaining higher power density under the same external resistance. PMID:16450042

  12. Analysis of Dyes Extracted from Millimeter-Size Nylon Fibers by Micellar Electrokinetic Chromatography

    SciTech Connect

    Lewis, L.A.

    2001-07-30

    The Learning Objective is to present to the forensic community a potential qualitative/quantitative method for trace-fiber color comparisons using micellar electrokinetic chromatography (MEKC). Developing a means of analyzing extracted dye constituents from millimeter-size nylon fiber samples was the objective of this research initiative. Aside from ascertaining fiber type, color evaluation and source comparison of trace-fiber evidence plays a critical role in forensic-fiber examinations. Literally thousands of dyes exist to date, including both natural and synthetic compounds. Typically a three-color-dye combination is employed to affect a given color on fiber material. The result of this practice leads to a significant number of potential dye combinations capable of producing a similar color and shade. Since a typical forensic fiber sample is 2 mm or less in length, an ideal forensic dye analysis would qualitatively and quantitatively identify the extracted dye constituents from a sample size of 1 mm or smaller. The goal of this research was to develop an analytical method for comparing individual dye constituents from trace-fiber evidence with dyes extracted from a suspected source, while preserving as much of the original evidence as possible.

  13. Investigation of the electrokinetic properties of paraffin suspension. 2. In cationic and anionic surfactant solutions.

    PubMed

    Chibowski, Emil; Wiacek, Agnieszka; Holysz, Lucyna; Terpilowski, Konrad

    2005-08-16

    Electrical phenomena at nonionogenic hydrophobic surfaces (solid or liquid) in water, electrolyte, and/or surfactant solutions still attract research. In part 1 of this paper we described the electrokinetic behavior of paraffin wax suspension in water and electrolyte solutions (NaCl or LaCl3). On the basis of the latest data of water structure near hydrophobic surfaces it was concluded that immobilized water dipoles at the interface can play an essential role in the zeta potential formation. In this paper were investigated the zeta potentials of paraffin wax in cationic surfactants cetyltrimethylammonium bromide, C16H33(CH3)3NBr, and octadecyltrimethylammonium chloride, C18H37(CH3)3NCl, and anionic surfactant sodium dodecyl sulfate, C12H25SO4Na. Also changes in wettability of the paraffin surface due to the surfactant's adsorption were studied via wetting contact angle measurements and calculation of the surface free energy. It was concluded that at a low surfactant concentration (10(-6) M) the water dipole structure still contributes to the zeta potential, but at a higher one the zeta potential is determined by the surfactant molecules' adsorption. A special role of OH- ions is also clearly seen. Moreover, a functional relationship was found between the surface free energy of the surfactant-covered paraffin surface and the zeta potential. PMID:16089367

  14. Determination of phthalates in food packing materials by electrokinetic chromatography with polymeric pseudostationary phase.

    PubMed

    Ni, Xinjiong; Xing, Xiaoping; Cao, Yuhua; Cao, Guangqun

    2016-01-01

    Polymeric pseudostationary phase (PSP), formed by random copolymer poly (stearyl methacrylate-co-methacrylic acid) (P(SMA-co-MAA)), was used in electrokinetic chromatography (EKC) to separate 15 kinds of phthalates (PAEs). The organic solvent modifier is a key factor for the separation of PAEs. Without organic solvents, only four kinds of PAEs with smaller molecular weight could be separated in the running buffer containing 1% P(SMA-co-MAA). The other eleven kinds of PAEs with larger molecular weight could be separated within 25 min by adding 40% (v/v) methanol and 2% (v/v) 1-butanol in the running buffer. The linear ranges of 15 kinds of PAEs were between 2 and 200mg/L, and the limit of detection based on the ratio of signal to noise of 3 were between 1 and 3mg/L. The method was applied to determination of PAEs in 6 kinds of food packing materials. The recoveries were between 81% and 118% with the RSD less than 4%. PMID:26212987

  15. Simultaneous determination of ten preservatives in ten kinds of foods by micellar electrokinetic chromatography.

    PubMed

    Ding, Xiao-Jing; Xie, Na; Zhao, Shan; Wu, Yu-Chen; Li, Jiang; Wang, Zhi

    2015-08-15

    An improved micellar electrokinetic capillary chromatography method (MEKC) for the simultaneous determination of ten preservatives in ten different kinds of food samples was reported. An uncoated fused-silica capillary with 50 ?m i.d. and 70 cm total length was used. Under the optimized conditions, the linear response was observed in the range of 1.2-200mg/L for the analytes. The limits of detection (LOD, S/N=3) and limits of quantitation (LOQ, S/N=10) ranging from 0.4 to 0.5mg/L and 1.2 to 1.5mg/L, respectively were obtained. The method was used for the determination of sorbic and benzoic acids in two FAPAS® (Food Analysis Performance Assessment Scheme) proficiency test samples (jam and chocolate cake). The results showed that the current method with simple sample pretreatment and small reagent consumption could meet the needs for routine analysis of the ten preservatives in ten types of food products. PMID:25794741

  16. Selective and quantitative analysis of 4-hydroxybenzoate preservatives by microemulsion electrokinetic chromatography.

    PubMed

    Mahuzier, P E; Altria, K D; Clark, B J

    2001-07-27

    A microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for the determination of 4-hydroxybenzoates and their impurities. These materials are commonly known as parabens and are widely used as preservatives in foods, cosmetics and pharmaceuticals. The method was shown to be selective and quantitative for the methyl, ethyl, propyl and butyl esters of 4-hydroxybenzoic acid. An internal standard, 4-hydroxyacetophenone, was employed to improve injection precision and detector linearity. In addition, 4-hydroxybenzoic acid, the major degradent, could also be monitored at the 0.1% (m/m) level. The method was successfully validated for assay and detection of the impurities in 4-hydroxybenzoic acid methyl ester and 4-hydroxybenzoic acid propyl ester samples and for the determination of 4-hydroxybenzoic acid methyl ester in a liquid pharmaceutical formulation. The determination of paraben content by MEEKC in a liquid sample was consistent with HPLC analysis. This work is the first reported validated MEEKC method and shows that the methodology can be successfully implemented into routine quality control testing. PMID:11521898

  17. Quantitative determination of S-alk(en)ylcysteine-S-oxides by micellar electrokinetic capillary chromatography.

    PubMed

    Kubec, Roman; Dadáková, Eva

    2008-11-28

    A novel method for determination of S-alk(en)ylcysteine-S-oxides by capillary electrophoresis has been developed and validated. The method is based on extraction of these sulfur amino acids by methanol, their derivatization by fluorenylmethyl chloroformate and subsequent separation by micellar electrokinetic capillary chromatography. Main advantages of the new method are simplicity, sensitivity, high specificity and very low running costs, making it suitable for routine analysis of a large number of samples. Employing this method, the content of S-alk(en)ylcysteine-S-oxides was determined in 12 commonly consumed alliaceous and cruciferous vegetables (e.g. garlic, onion, leek, chive, cabbage, radish, cauliflower and broccoli). The total content of these amino acids in the Allium species evaluated varied between 0.59 and 12.3mg g(-1) fresh weight. Whereas alliin was found only in garlic, isoalliin was the major S-alk(en)ylcysteine-S-oxide in onion, leek, chive and shallot. On the other hand, the cruciferous species analyzed contained only methiin in the range of 0.06-2.45mg g(-1) fresh weight. PMID:18952220

  18. Electrokinetic and Hemostatic Profiles of Nonwoven Cellulosic/Synthetic Fiber Blends with Unbleached Cotton

    PubMed Central

    Edwards, J. Vincent; Graves, Elena; Bopp, Alvin; Prevost, Nicolette; Santiago, Michael; Condon, Brian

    2014-01-01

    Greige cotton contains waxes and pectin on the outer surface of the fiber that are removed when bleached, but these components present potential wound dressing functionality. Cotton nonwovens blended with hydrophobic and hydrophilic fibers including viscose, polyester, and polypropylene were assessed for clotting activity with thromboelastography (TEG) and thrombin production. Clotting was evaluated based on TEG measurements: R (time to initiation of clot formation), K (time from end of R to a 20 mm clot), ? (rate of clot formation according to the angle tangent to the curve as K is reached), and MA (clot strength). TEG values correlate to material surface polarity as measured with electrokinetic parameters (?plateau, ?? and swell ratio). The material surface polarity (?plateau) varied from ?22 to ?61 mV. K values and thrombin concentrations were found to be inversely proportional to ?plateau with an increase in material hydrophobicity. An increase in the swell ratios of the materials correlated with decreased K values suggesting that clotting rates following fibrin formation increase with increasing material surface area due to swelling. Clot strength (MA) also increased with material hydrophobicity. Structure/function implications from the observed clotting physiology induced by the materials are discussed. PMID:25459983

  19. Headspace in-tube microextraction coupled with micellar electrokinetic chromatography of neutral aromatic compounds.

    PubMed

    Cho, Sung Min; Park, Bum Su; Jung, Woo Sung; Lee, Sang Won; Jung, Yunhwan; Chung, Doo Soo

    2016-02-01

    Headspace (HS) extraction can be carried out easily and aptly via single drop microextraction coupled with capillary electrophoresis (CE). However, one drawback is the difficulty of keeping the single drop stably at the capillary tip. To solve this problem, we have recently demonstrated HS in-tube microextraction (ITME) of acidic compounds such as chlrophenols in an acidic sample using a basic run buffer plug in the separation capillary for CE as an acceptor phase. In this report, an organic acceptor plug in a capillary was used to extract neutral organic volatile pollutants such as BTEX (benzene, toluene, ethylbenzene, and m-xylene). After extraction, the analytes enriched in the organic acceptor plug were analyzed with micellar electrokinetic chromatography (MEKC). The enrichment factors for BTEX in a standard solution were up to 350 under an optimal condition of 25°C for 20min. As an application, BTEX spiked into bottled water were analyzed with HS-ITME-MEKC, and the enrichment factors for BTEX were up to 320. The limits of detections were 1-4ppb, which are at least 200 times lower than the US Environmental Protection Agency guidelines for drinking water, except benzene. The entire procedure of HS-ITME-MEKC was carried out automatically using a commercial CE instrument. PMID:26653509

  20. Label-free biomolecular detection at electrically displaced liquid interfaces using interfacial electrokinetic transduction (IET).

    PubMed

    Mavrogiannis, Nicholas; Crivellari, Francesca; Gagnon, Zachary R

    2016-03-15

    Biosensors require a biorecognition element that specifically binds to a target analyte, and a signal transducer, which converts this targeted binding event into a measurable signal. While current biosensing methods are capable of sensitively detecting a variety of target analytes in a laboratory setting, there are inherent difficulties in developing low-cost portable biosensors for point-of-care diagnostics using traditional optical, mass, or electroanalytical-based signal transducers. It is therefore important to develop new biosensing transducer elements for recognizing binding events at low cost and in portable environments. Here, we demonstrate a novel electrokinetic liquid biosensing method for the sensitive label-free detection of a model biomolecule against a background of serum protein. The biosensor is based on the motion of a microfluidic-generated electrical liquid interface when subjected to an external alternating current electrical field. We demonstrate that the electric field-induced motion of the interface can be used as a sensitive and specific transducer for the detection of avidin at femtomolar concentrations in solution. This new detection strategy does not require surface functionalization or fluorescent labels, and has the potential to serve as a sensitive low-cost method for portable biomarker detection. PMID:26513285

  1. Electrokinetic self-Propulsion of a Catalytic Nanomotor; a Perturbation Analysis

    NASA Astrophysics Data System (ADS)

    Nourhani, Amir; Lammert, Paul; Borhan, Ali; Crespi, Vincent

    2011-11-01

    The development of bimetallic catalytic nanomotors has been one of many attempts to mimic the behavior of bionanomotors and micro-organisms. Recent experimental analysis has shown that electrokinetic self-propulsion is the dominant mechanism for autonomous motion of these nanomotors in hydrogen peroxide. In this work, we propose a mathematical model for the steady state locomotion of an axisymmetric spherical nanomotor in a symmetric binary electrolyte. The asymmetric production and consumption of hydrogen ions on the surface of the particle is modeled by a general position-dependent flux. The flux of negative ions on the surface is zero. Using perturbation analysis and the method of matched asymptotic expansion, we solve the model for the velocity of the particle to the leading order in Debye length and to the first order in the intensity of hydrogen ions flux. The velocity depends linearly on the interfacial potential of the surface of the particle and the intensity of hydrogen ions flux. It also inversely depends on the viscosity of fluid, the ion concentration in electrolyte and the diffusion coefficient of the hydrogen ions. The predicted behavior is consistent with experimental results and numerical calculations. The work is funded by MRSEC at Penn State University.

  2. Separation and determination of nimesulide related substances for quality control purposes by micellar electrokinetic chromatography.

    PubMed

    Zacharis, Constantinos K; Tzanavaras, Paraskevas D; Notou, Maria; Zotou, Anastasia; Themelis, Demetrius G

    2009-02-20

    A micellar electrokinetic chromatography (MEKC) method has been developed and validated for the determination of nimesulide related compounds in pharmaceutical formulations. Electrophoretic separation of six European Pharmacopoeia (EP) impurities (A-F) was performed using a fused silica capillary (L(eff.)=50 cm, L(tot.)=57 cm, 50 microm i.d.) with a background electrolyte (BGE) containing 25 mM borate buffer (pH 9.5), 30 mM sodium dodecyl sulphate and phi=3% (v/v) acetonitrile. The influence of several factors (surfactant and buffer concentration, pH, organic modifier, applied voltage, capillary temperature and injection time) was studied. The method was suitably validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. The calibration curves obtained for the six compounds were linear over the range 5-12 microgml(-1) (0.05-0.12%). The relative standard deviations (s(r)) of intra- and inter-day experiments were less than 5.0%. The detection limits ranged between 0.7 and 1.6 microgml(-1) depending on the impurity. The proposed method was applied successfully to the quantification of nimesulide impurities in its pharmaceutical formulation. PMID:19062217

  3. Combination of bioremediation and electrokinetics for the in-situ treatment of diesel polluted soil: A comparison of strategies.

    PubMed

    Mena Ramírez, Esperanza; Villaseñor Camacho, José; Rodrigo, Manuel A; Cañizares, Pablo

    2015-11-15

    The aim of this work is to compare different strategies based on electrokinetic soil flushing and bioremediation for the remediation of diesel-polluted soil. Four options were tested at the laboratory scale: single bioremediation (Bio), performed as a control test; a direct combination of electrokinetic soil flushing and biological technologies (EKSF-Bio); EKSF-Bio with daily polarity reversal of the electric field (PR-EKSF-Bio); and a combination of electrokinetic soil flushing and a permeable reactive biological barrier (EKSF-BioPRB). Four batch experiments of 14 days duration were carried out for comparing technologies at room temperature with an electric field of 1.0 V cm(-1) (in EKSF). A diesel degrading microbial consortium was used. The experimental procedure and some specific details, such as the flushing fluids used, varied depending on the strategy. When using the EKSF-Bio option, a high buffer concentration was required to control the pH, causing soil heating, which negatively affected the biological growth and thus the diesel removal. The PR-EKSF-Bio and the EKSF-BioPRB options attained suitable operating conditions and improved the transport processes for biological growth. Polarity reversal was an efficient option for pH, moisture and temperature control. Homogeneous microbial growth was observed, and approximately 20% of the diesel was removed. The BioPRB option was not as efficient as PR-EKSF-Bio in controlling the operating conditions, but the central biobarrier protected the biological activity. Microbial growth was observed not only in the biobarrier but also in a large portion of the soil, and 29% of the diesel was removed in the short remediation test. PMID:26172598

  4. Engineering Urban Green Space Projects Incorporating

    E-print Network

    Yasuda, Masami

    Engineering Urban Green Space Projects Incorporating the Therapeutic Effects of Plants Associate Professor, Graduate School of Horticulture Yutaka Iwasaki The functions required of urban green spaces have in the course of our daily lives. To that end, as well as test for the remedial effects that urban green spaces

  5. Equilibrium properties of charged spherical colloidal particles suspended in aqueous electrolytes: finite ion size and effective ion permittivity effects.

    PubMed

    López-García, José Juan; Horno, José; Grosse, Constantino

    2012-08-15

    The equilibrium properties of a charged spherical colloidal particle immersed in an aqueous electrolyte solution are examined using an extension of the Standard Electrokinetic Model that takes into account the finite ion size by modeling the aqueous electrolyte solution as a suspension of polarizable insulating spheres in water. We find that this model greatly amplifies the steric effects predicted by the usual modified Poisson-Boltzmann equation, which only imposes a restriction on the ability of ions to approach one another. This suggests that a solution of the presented model under nonequilibrium conditions could have important consequences in the interpretation of dielectric and electrokinetic data in colloidal suspensions. PMID:22683215

  6. Dispersive liquid-liquid microextraction for the determination of phenols by acetonitrile stacking coupled with sweeping-micellar electrokinetic chromatography with large-volume injection.

    PubMed

    He, Hui; Liu, Shuhui; Meng, Zhaofu; Hu, Shibing

    2014-09-26

    The current routes to couple dispersive liquid-liquid microextraction (DLLME) with capillary electrophoresis (CE) are evaporation of water immiscible extractants and backextraction of analytes. The former is not applicable to extractants with high boiling points, the latter being effective only for acidic or basic analytes, both of which limit the further application of DLLME-CE. In this study, with 1-octanol as a model DLLME extractant and six phenols as model analytes, a novel method based on acetonitrile stacking and sweeping is proposed to accomplish large-volume injection of 1-octanol diluted with a solvent-saline mixture before micellar electrokinetic chromatography. Brij-35 and ?-cyclodextrin were employed as pseudostationary phases for sweeping and also for improving the compatibility of sample zone and aqueous running buffer. A short solvent-saline plug was used to offset the adverse effect of the water immiscible extractant on focusing efficiency. The key parameters affecting separation and concentration were systematically optimized; the effect of Brij-35 and 1-octanol on focusing mechanism was discussed. Under the optimized conditions, with ? 30-fold concentration enrichment by DLLME, the diluted extractant (8×) was then injected into the capillary with a length of 21 cm (42% of the total length), which yielded the overall improvements in sensitivity of 170-460. Limits of detection and qualification ranged from 0.2 to 1.0 ng/mL and 1.0 to 3.4 g/mL, respectively. Acceptable repeatability lower than 3.0% for migration time and 9.0% for peak areas were obtained. The developed method was successfully applied for analysis of the phenol pollutants in real water samples. PMID:25155065

  7. Revealing fibrinogen monolayer conformations at different pHs: electrokinetic and colloid deposition studies.

    PubMed

    Nattich-Rak, Ma?gorzata; Adamczyk, Zbigniew; Wasilewska, Monika; Sadowska, Marta

    2015-07-01

    Adsorption mechanism of human fibrinogen on mica at different pHs is studied using the streaming potential and colloid deposition measurements. The fibrinogen monolayers are produced by a controlled adsorption under diffusion transport at pH of 3.5 and 7.4. Initially, the electrokinetic properties of these monolayers and their stability for various ionic strength are determined. It is shown that at pH 3.5 fibrinogen adsorbs irreversibly on mica for ionic strength range of 4×10(-4) to 0.15 M. At pH 7.4, a partial desorption is observed for ionic strength below 10(-2) M. This is attributed to the desorption of the end-on oriented molecules whereas the side-on adsorbed molecules remain irreversibly bound at all ionic strengths. The orientation of molecules and monolayer structure is evaluated by the colloid deposition measurements involving negatively charged polystyrene latex microspheres, 820 nm in diameter. An anomalous deposition of negative latex particles on substrates exhibiting a negative zeta potential is observed. At pH 3.5 measurable deposition of latex is observed even at low ionic strength where the approach distance of latex particles exceeded 70 nm. At pH 7.4 this critical distance is 23 nm. This confirms that fibrinogen monolayers formed at both pHs are characterized by the presence of the side-on and end-on oriented molecules that prevail at higher coverage range. It is also shown that positive charge is located at the end parts of the ?A chains of the adsorbed fibrinogen molecules. Therefore, it is concluded that the colloid deposition method is an efficient tool for revealing protein adsorption mechanisms at solid/electrolyte interfaces. PMID:25453169

  8. Modified micellar electrokinetic chromatography in the analysis of catechins and xanthines in chocolate.

    PubMed

    Gotti, Roberto; Fiori, Jessica; Mancini, Francesca; Cavrini, Vanni

    2004-10-01

    Modified micellar electrokinetic chromatography (MEKC) analysis of monomeric flavanols (catechin and epicatechin) and methylxanthines (caffeine and theobromine) in chocolate and cocoa was performed by using sodium dodecyl sulfate (SDS) as a principal component of the running buffer. Because of the reported poor stability of catechins in alkaline solutions, acidic conditions (pH 2.5) were chosen and consequently the electroosmotic flow (EOF) was significantly suppressed; this resulted in a fast anodic migration of the analytes partitioned into the SDS micelles. Under these conditions, variations of either pH value in acidic range or SDS concentration, showed to be not suitable to modulate the selectivity. To overcome this limit, use of additives to the SDS-based running buffer was successfully applied and three different systems were optimized for the separation of (+)-catechin, (-)-epicatechin, caffeine, and theobromine in chocolate and cocoa powder samples. In particular, two mixed micelle systems were applied; the first consisted of a mixture of SDS and 3-[(3-cholamidopropyl)dimethylammonio]-1-propansulfonate (CHAPS) with a composition of 90 mM and 10 mM, respectively; the second was SDS and taurodeoxycholic acid sodium salt (TDC) with a composition of 70 mM and 30 mM, respectively. A further MEKC approach was developed by addition of 10 mM hydroxypropyl-beta-cyclodextrin (HP-beta-CD) to the SDS solution (90 mM); it provided a useful cyclodextrin(CD)-modified MEKC. By applying the optimized conditions, different separation profiles of the flavanols and methylxanthines were obtained showing interesting potential of these combined systems; their integrated application showed to be useful for the identification of the low level of (+)-catechin in certain real samples. The CD-MEKC approach was validated and applied to the determination of catechins and methylxanthines in aqueous extracts from four different commercial chocolate types (black and milk) and two cocoa powders. PMID:15472952

  9. Effect of the growth temperature and the AlN mole fraction on In incorporation and properties of quaternary III-nitride layers grown by molecular beam epitaxy

    SciTech Connect

    Fernandez-Garrido, S.; Pereiro, J.; Munoz, E.; Calleja, E.; Gago, R.; Bertram, F.; Christen, J.; Luna, E.; Trampert, A.

    2008-10-15

    Indium incorporation into wurtzite (0001)-oriented In{sub x}Al{sub y}Ga{sub 1-x-y}N layers grown by plasma-assisted molecular beam epitaxy was studied as a function of the growth temperature (565-635 deg. C) and the AlN mole fraction (0.01incorporation decreased continuously with increasing growth temperature due to thermally enhanced dissociation of In-N bonds and for increasing AlN mole fractions. High resolution x-ray diffraction and transmission electron microscopy (TEM) measurements did not show evidence of phase separation. The mosaicity of the quaternary layers was found to be mainly determined by the growth temperature and independent on alloy composition within the range studied. However, depending on the AlN mole fraction, nanometer-sized composition fluctuations were detected by TEM. Photoluminescence spectra showed a single broad emission at room temperature, with energy and bandwidth S- and W-shaped temperature dependences typical of exciton localization by alloy inhomogeneities. Cathodoluminescence measurements demonstrated that the alloy inhomogeneities, responsible of exciton localization, occur on a lateral length scale below 150 nm, which is corroborated by TEM.

  10. Creating sub-50 nm nanofluidic junctions in a PDMS microchip via self-assembly process of colloidal silica beads for electrokinetic concentration of biomolecules.

    PubMed

    Syed, A; Mangano, L; Mao, P; Han, J; Song, Y-A

    2014-12-01

    In this work we describe a novel and simple self-assembly process of colloidal silica beads to create a nanofluidic junction between two microchannels. The nanoporous membrane was used to induce ion concentration polarization inside the microchannel and this electrokinetic preconcentration system allowed rapid concentration of DNA samples by ~1700 times and of protein samples by ~100 times within 5 minutes. PMID:25254651

  11. MicrofluIdic circuit designs for performing electrokinetic manipulations that reduce the number of voltage sources and fluid reservoirs

    DOEpatents

    Jacobson, Stephen C. (Knoxville, TN); Ramsey, J. Michael (Knoxville, TN)

    2000-01-01

    A microfabricated device and method for proportioning and mixing electrokinetically manipulated biological or chemical materials is disclosed. The microfabricated device mixes a plurality of materials in volumetric proportions controlled by the electrical resistances of tributary reagent channels through which the materials are transported. The microchip includes two or more tributary reagent channels combining at one or more junctions to form one or more mixing channels. By varying the geometries of the channels (length, cross section, etc.), a plurality of reagent materials can be mixed at a junction such that the proportions of the reagent materials in the mixing channel depend on a ratio of the channel geometries and material properties. Such an approach facilitates voltage division on the microchip without relying on external wiring schemes and voltage division techniques external to the microchip. Microchannel designs that provide the necessary voltage division to accomplish electrokinetic valving operations using a single voltage source and a switch are also described. In addition, microchannel designs that accomplish fluidic operation utilizing a minimal number of fluidic reservoirs are disclosed.

  12. Rapid (<5?min) Identification of Pathogen in Human Blood by Electrokinetic Concentration and Surface-Enhanced Raman Spectroscopy

    PubMed Central

    I-Fang Cheng; Chang, Hsien-Chang; Chen, Tzu-Ying; Hu, Chenming; Yang, Fu-Liang

    2013-01-01

    This study reports a novel microfluidic platform for rapid and long-ranged concentration of rare-pathogen from human blood for subsequent on-chip surface-enhanced Raman spectroscopy (SERS) identification/discrimination of bacteria based on their detected fingerprints. Using a hybrid electrokinetic mechanism, bacteria can be concentrated at the stagnation area on the SERS-active roughened electrode, while blood cells were excluded away from this region at the center of concentric circular electrodes. This electrokinetic approach performs isolation and concentration of bacteria in about three minutes; the density factor is increased approximately a thousand fold in a local area of ~5000 ?m2 from a low bacteria concentration of 5 × 103?CFU/ml. Besides, three genera of bacteria, S. aureus, E. coli, and P. aeruginosa that are found in most of the isolated infections in bacteremia were successfully identified in less than one minute on-chip without the use of any antibody/chemical immobilization and reaction processes. PMID:23917638

  13. Study of a novel sample injection method (floating electrokinetic supercharging) for high-performance microchip electrophoresis of DNA fragments.

    PubMed

    Hirokawa, Takeshi; Takayama, Yoichi; Arai, Akihiro; Xu, Zhongqi

    2008-05-01

    Aiming to achieve high-performance analysis of DNA fragments using microchip electrophoresis, we developed a novel sample injection method, which was given the name of floating electrokinetic supercharging (FEKS). In the method, electrokinetic injection (EKI) and ITP preconcentration of samples was performed in a separation channel, connecting two reservoir ports (P3 and P4) on a cross-geometry microchip. At these two stages, side channels, crossing the separation channel, and their ports (P1 and P2) were electrically floated. After the ITP-stacked zones passed the cross-part, they were eluted for detection by using leading ions from P1 and P2 that enabled electrophoresis mode changing rapidly from ITP to zone electrophoresis (ZE). Possible sample leakage at the cross-part toward P1 and P2 was studied in detail on the basis of computer simulation using a CFD-ACE+ software and real experiments, through which it was validated that the analyte recovery to the separation channel was almost complete. The FEKS method successfully contributed to higher resolution and shorter analysis time of DNA fragments on the cross-microchip owing to more rapid switching from ITP status to ZE separation in comparison with our previous EKS procedure realized on a single-channel microchip. Without any degradation of resolution, the achieved LODs were on average ten times better than using conventional pinched injection. PMID:18393341

  14. Rapid (<5 min) Identification of Pathogen in Human Blood by Electrokinetic Concentration and Surface-Enhanced Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    I-Fang Cheng; Chang, Hsien-Chang; Chen, Tzu-Ying; Hu, Chenming; Yang, Fu-Liang

    2013-08-01

    This study reports a novel microfluidic platform for rapid and long-ranged concentration of rare-pathogen from human blood for subsequent on-chip surface-enhanced Raman spectroscopy (SERS) identification/discrimination of bacteria based on their detected fingerprints. Using a hybrid electrokinetic mechanism, bacteria can be concentrated at the stagnation area on the SERS-active roughened electrode, while blood cells were excluded away from this region at the center of concentric circular electrodes. This electrokinetic approach performs isolation and concentration of bacteria in about three minutes; the density factor is increased approximately a thousand fold in a local area of ~5000 ?m2 from a low bacteria concentration of 5 × 103 CFU/ml. Besides, three genera of bacteria, S. aureus, E. coli, and P. aeruginosa that are found in most of the isolated infections in bacteremia were successfully identified in less than one minute on-chip without the use of any antibody/chemical immobilization and reaction processes.

  15. Electrokinetic remediation of plutonium-contaminated nuclear site wastes: results from a pilot-scale on-site trial.

    PubMed

    Agnew, Kieran; Cundy, Andrew B; Hopkinson, Laurence; Croudace, Ian W; Warwick, Phillip E; Purdie, Philip

    2011-02-28

    This paper examines the field-scale application of a novel low-energy electrokinetic technique for the remediation of plutonium-contaminated nuclear site soils, using soil wastes from the Atomic Weapons Establishment (AWE) Aldermaston site, Berkshire, UK as a test medium. Soils and sediments with varying composition, contaminated with Pu through historical site operations, were electrokinetically treated at laboratory-scale with and without various soil pre-conditioning agents. Results from these bench-scale trials were used to inform a larger on-site remediation trial, using an adapted containment pack with battery power supply. 2.4 m(3) (ca. 4t onnes) of Pu-contaminated soil was treated for 60 days at a power consumption of 33 kWh/m(3), and then destructively sampled. Radiochemical data indicate mobilisation of Pu in the treated soil, and migration (probably as a negatively charged Pu-citrate complex) towards the anodic compartment of the treatment cell. Soil in the cathodic zone of the treatment unit was remediated to a level below free-release disposal thresholds (1.7 Bq/g, or <0.4 Bq/g above background activities). The data show the potential of this method as a low-cost, on-site tool for remediation of radioactively contaminated soils and wastes which can be operated remotely on working sites, with minimal disruption to site infrastructure or operations. PMID:21227583

  16. Electrokinetic in situ oxidation remediation: assessment of parameter sensitivities and the influence of aquifer heterogeneity on remediation efficiency.

    PubMed

    Wu, Ming Zhi; Reynolds, David A; Fourie, Andy; Prommer, Henning; Thomas, David G

    2012-08-01

    A newly developed groundwater and electrokinetic (EK) flow and reactive transport numerical model was applied to simulate electrokinetic in situ chemical oxidation (EK-ISCO) remediation. Scenario simulations that considered the oxidation of a typical organic contaminant (tetrachloroethene) by permanganate were used to gain a better understanding of the key processes and parameters that control remediation efficiency. In a first step a sensitivity analysis was carried out to investigate a range of EK, hydraulic and engineering parameters on the performance of EK-ISCO. While all investigated parameters affected the remediation process to some extent, the duration and energy required for remediation were shown to be most dependent upon the applied voltage gradient, the natural oxidant demand and the concentration of the injected oxidant. Secondly, the efficacy of EK-induced oxidant transport was further examined for a heterogeneous aquifer system with random permeability fields. Oxidant migration under EK was slower in low-permeability media due to the increased oxidant consumption of competing reductants. Instead of injecting oxidant only at the cathode, locating injection wells between the electrodes greatly increased the contaminant degradation by decreasing the distance the amendment had to migrate before reaching the contaminant. PMID:22684143

  17. Incorporation of thieno[3,2-b]thiophene moieties as novel electropolymerizable groups in a conducting metallopolymer and study of the effect on photostability.

    PubMed

    Caraway, Jennifer D; Nguyen, Minh T; Mitchell, Lauren A; Holliday, Bradley J

    2015-04-01

    A novel nickel(II)-containing conducting metallopolymer utilizing thieno[3,2-b]thiophene moieties as the electropolymerizable groups is synthesized and characterized. A metal-free polymer is also obtained via electropolymerization of the title ligand allowing comparative studies of the electrochemical and spectroscopic properties of the polymer system in the presence and absence of nickel(II) metal ions. Photodegradation of the two polymers is studied along with an analogous system incorporating bithiophene as the electropolymerizable groups. Stability is found to be comparable between the metal-free thieno[3,2-b]thiophene- and bithio-phene-based polymers; however, significant enhancement is observed in the thieno[3,2-b]thiophene-based nickel(II) conducting metallopolymer. PMID:25648116

  18. Effect of the nitrogen incorporation and fast carrier dynamics in (In,Ga)AsN/GaP self-assembled quantum dots

    SciTech Connect

    Gauthier, J.-P.; Almosni, S.; Léger, Y.; Perrin, M.; Even, J.; Cornet, C. Durand, O.; Robert, C.; Balocchi, A.; Carrère, H.; Marie, X.

    2014-12-15

    We report on the structural and optical properties of (In,Ga)AsN self-assembled quantum dots grown on GaP (001) substrate. A comparison with nitrogen free (In,Ga)As system is presented, showing a clear modification of growth mechanisms and a significant shift of the photoluminescence spectrum. Low temperature carrier recombination dynamics is studied by time-resolved photoluminescence, highlighting a drastic reduction of the characteristic decay-time when nitrogen is incorporated in the quantum dots. Room temperature photoluminescence is observed at 840?nm. These results reveal the potential of (In,Ga)AsN as an efficient active medium monolithically integrated on Si for laser applications.

  19. Effect of Fe incorporation on the optical behavior of ZnO thin films prepared by sol-gel derived spin coating techniques

    NASA Astrophysics Data System (ADS)

    Rakkesh, R. Ajay; Malathi, R.; Balakumar, S.

    2013-02-01

    In this work, Fe doped Zinc Oxide (ZnO) thin films were fabricated on the glass substrate by sol-gel derived spin coating technique. X-ray Diffraction studies revealed that the obtained pure and Fe doped ZnO thin films were in the wurtzite and spinel phase respectively. The three well defined Raman lines at 432, 543 and 1091 cm-1 also confirmed the lattice structure of the ZnO thin film has wurtzite symmetry. While doping Fe atoms in the ZnO, there was a significant change in the phase from wurtzite to spinel structure; owing to Fe (III) ions being incorporated into the lattice through substitution of Zn (II) ions. Room temperature PL spectra showed that the role of defect mediated red emissions at 612 nm was due to radial recombination of a photogenerated hole with an electron that belongs to the Fe atoms, which were discussed in detail.

  20. The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N2O emissions from an intensively managed vegetable field in southeastern China

    NASA Astrophysics Data System (ADS)

    Li, B.; Fan, C. H.; Xiong, Z. Q.; Li, Q. L.; Zhang, M.

    2015-03-01

    An experiment was conducted to study the influences of nitrification inhibitor (NI) and biochar incorporation on yield-scaled N2O using the static chamber method and gas chromatography in an intensively managed vegetable field with seven consecutive vegetable crops from 2012 to 2014 in southeastern China. With an equal annual nitrogen (N) application rate (1217 kg N ha-1 yr-1), six treatments under three biochar amendment rates - namely, 0 t ha-1 (C0), 20 t ha-1 (C1) and 40 t ha-1 (C2) - with compound fertilizer (CF) or urea mixed with NI of nitrapyrin as chlorinated pyridine (CP) were studied in these field experiments. The results showed that, although there was no significant influence on soil organic carbon (SOC) content or total nitrogen (TN), nitrapyrin could result in a significant increase in soil pH during the experimental period. Nitrapyrin significantly decreased cumulative N2O emissions by 15.9-32.1% while increasing vegetable yield by 9.8-41.9%. Thus, it also decreased yield-scaled N2O emissions significantly. In addition to the differential responses of the soil pH, biochar amendment significantly increased SOC and TN. Compared with the treatments without biochar addition, the cumulative N2O emissions showed no significant difference in the CF or the CP group treatments but increased slightly (not significantly) by 7.9-18.3% in the CP group treatments. Vegetable yield was enhanced by 7.1-49.5% in the CF group treatments compared with the treatments without biochar amendment, while there was no significant difference in the CP group treatments, and the yield-scaled N2O emissions were thus decreased significantly. Furthermore, treatments involving with nitrapyrin and biochar incorporation slightly increased yield-scaled N2O emissions by 9.4%, on average, compared with CP-C0. Therefore, the application of nitrapyrin could serve as an appropriate practice for increasing vegetable yield and mitigating N2O emissions in intensively managed vegetable fields and should be further examined in various agroecosystems.