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Effects of electrostatic correlations on electrokinetic phenomena  

NASA Astrophysics Data System (ADS)

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

Storey, Brian D.; Bazant, Martin Z.



Effects of electrostatic correlations on electrokinetic phenomena  

E-print Network

The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper ...

Storey, Brian D.


Electrokinetic remediation of concrete: Effect of chelating agents  

Microsoft Academic Search

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

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



Interfacial electrokinetic effects on liquid flow in microchannels  

Microsoft Academic Search

The presence of the electrical double layer near a solid–liquid interface results in the electro-viscous effect on pressure-driven liquid flow through microchannels. The objective of this paper is to examine the magnitude of the additional flow resistance caused by the electrokinetic effect in microchannels. De-ionized ultra-filtered water and aqueous KCl solutions of two different concentrations (10?4 and 10?2 M) were

Liqing Ren; Weilin Qu; Dongqing Li



Modeling forced liquid convection in rectangular microchannels with electrokinetic effects  

Microsoft Academic Search

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

Chun Yang; Dongqing Li; Jacob H. Masliyah



Analytical and Numerical Study of Joule Heating Effects on Electrokinetically Pumped Continuous Flow PCR Chips  

E-print Network

Analytical and Numerical Study of Joule Heating Effects on Electrokinetically Pumped Continuous, and the potential for integration.1-3 Joule heating is inevitable when electrokinetic pumping is used Form: December 8, 2007 Joule heating is an inevitable phenomenon for microfluidic chips involving

Le Roy, Robert J.


Electrokinetic mixing at high zeta potentials: Ionic size effects on cross stream diffusion.  


The electrokinetic phenomena at high zeta potentials may show several unique features which are not normally observed. One of these features is the ionic size (steric) effect associated with the solutions of high ionic concentration. In the present work, attention is given to the influences of finite ionic size on the cross stream diffusion process in an electrokinetically actuated Y-shaped micromixer. The method consists of a finite difference based numerical approach for non-uniform grid which is applied to the dimensionless form of the governing equations, including the modified Poisson-Boltzmann equation. The results reveal that, neglecting the ionic size at high zeta potentials gives rise to the overestimation of the mixing length, because the steric effects retard liquid flow, thereby enhancing the mixing efficiency. The importance of steric effects is found to be more intense for channels of smaller width to height ratio. It is also observed that, in sharp contrast to the conditions that the ions are treated as point charges, increasing the zeta potential improves the cross stream diffusion when incorporating the ionic size. Moreover, increasing the EDL thickness decreases the mixing length, whereas the opposite is true for the channel aspect ratio. PMID:25514643

Ahmadian Yazdi, Alireza; Sadeghi, Arman; Saidi, Mohammad Hassan



Sub-Grid Modeling of Electrokinetic Effects in Micro Flows  

NASA Technical Reports Server (NTRS)

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

Chen, C. P.



Electrokinetic decontamination of concrete  

Microsoft Academic Search

ELECTROSORB Electrokinetic Extraction Technology, developed by ISOTRON Corp., offers a cost-effective approach to treating contaminated concrete. Heavy metals\\/radionuclides trapped in concrete can be extracted using this process if they are chemically solubilized; solubilizers used are citric acid alone and a mixture of citric and nitric acids. A DC electric field is applied across the contaminated concrete to electrokinetically transport the

H. L. Lomasney; A. K. SenGupta; V. Yachmenev



Electrokinetic decontamination of concrete  

SciTech Connect

ELECTROSORB Electrokinetic Extraction Technology, developed by ISOTRON Corp., offers a cost-effective approach to treating contaminated concrete. Heavy metals/radionuclides trapped in concrete can be extracted using this process if they are chemically solubilized; solubilizers used are citric acid alone and a mixture of citric and nitric acids. A DC electric field is applied across the contaminated concrete to electrokinetically transport the solubilized contaminants from the concrete pores to a collector on the concrete surface. The collector is an extraction pad laid on the surface. The pad provides confinement for a planar electrode and solubilizer solution; it is operated under a vacuum to hold the pad against the concrete surface. Operation requires little attendance, reducing the workers` health hazards. The process incorporates a mechanism for recycling the solubilizer solution. A field demonstration of the process took place in Building 21 of DOE`s Mound facility in Miamisburg, OH, over 12 days in June 1996. The thorium species present in this building`s concrete floors included ThO{sub 2} and thorium oxalate. The nitric acid was found to facilitate Th extraction.

Lomasney, H.L.; SenGupta, A.K.; Yachmenev, V.



Effects of soil composition on the removal of chromium by electrokinetics  

Microsoft Academic Search

Electrokinetic experiments were conducted on three different types of soil: glacial till, kaolin and Na-montmorillonite, in order to investigate the effect of soil mineralogy and naturally occurring hematite (Fe2O3) on the removal of chromium from these soils. Batch tests were also performed to characterize Cr(VI) adsorption onto these soils. This study has shown that soils which contain high carbonate buffers,

Krishna R. Reddy; Usha S. Parupudi; Srinivas N. Devulapalli; Charlie Y. Xu



Effect of cosolvents on the desorption and electrokinetic transport of PAHs in soils  

SciTech Connect

This research was carried out to evaluate feasibility of using electrokinetic technique to remove hydrophobic organic pollutants from soils, with the assistance of cosolvent added to the conducting fluid. The experiments were carried out on glacial till clay with phenanthrene as the test compound. Three Organic cosolvents, n-butylamine; detrahydrofuran; and acetone were evaluated for their potential to enhance the phenanthrene desorption and transport in soil under electrical field. Results showed that the present of n-butylamine significantly enhance the desorption and electrokinetic transport of phenanthrene, about 43% of the phenanthrene added was removed after 127 days or 9 pore volumes. The effect of acetone on electrokinetic transport of phenanthrene was not as obvious as butylamine. With a constant effluent flow rate of only 0.25 ml/hr, phenanthrene was not detected after 144 days. The effluent flow in the tetrahydofuran experiments was minimal, and phenanthrene was no detected in the effluent. The use of water as conducting solution did not cause observable phenanthrene migration.

Li, A.; Cheung, K.A.; Reddy, K.R.; Wadden, R.A.



An assessment of the effectiveness and impact of electrokinetic remediation for pyrene-contaminated soil.  


The effectiveness of electrokinetic remediation for pyrene-contaminated soil was investigated by an anode-cathode separated system using a salt bridge. The applied constant voltage was 24V and the electrode gap was 24cm. Two types of soil (sandy soil and loam soil) were selected because of their different conductive capabilities. The initial concentrations of pyrene in these soil samples were 261.3mg/kg sandy soil and 259.8mg/kg loam soil. After treatment of the sandy soil and loam soil for seven days, 56.8% and 20.1% of the pyrene had been removed respectively. Under the same power supply voltage, the removal of the pollutant from the sandy soil was greater than that from the loam soil, due to the higher current and lower pH. Further analysis revealed that the effectiveness of electrokinetic remediation was affected by the energy expenditure, and was associated with changes in soil properties. PMID:25458684

Xu, Sujuan; Guo, Shuhai; Wu, Bo; Li, Fengmei; Li, Tingting



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


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

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



Electrokinetic effects in catalytic platinum-insulator Janus swimmers  

NASA Astrophysics Data System (ADS)

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

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



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

E-print Network

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.

Rafael Roa; Félix Carrique; Emilio Ruiz-Reina



Electrokinetic effect combined with surface-charge assumption: a possible generation mechanism of coseismic EM signals  

NASA Astrophysics Data System (ADS)

According to field observations, electromagnetic (EM) signals accompanying seismic waves can be recorded. The orders of magnitude of observed coseismic electric and magnetic signals associated with earthquakes are usually around 1 to 101 mV km-1 and 10-2 to 1 nT, respectively. In this paper, we carry out numerical simulation of coseismic EM signals associated with seismic waves due to electrokinetic effect and compare with field observations. The seismic source is represented by a finite fault measuring 15 × 9 km2 with a max slip displacement 1.5 m, corresponding to a Mw 5.9 earthquake. While using the EM surface boundary condition of continuous horizontal EM components, the magnetic signals only accompany the late-arriving S waves at receiver near the ground surface. This is obviously different from field observations. Thus, we adopt another EM surface boundary condition which assumes the ground surface carries surface charge. For the used half-space model, a surface-charge density magnitude |Qsc| in excess of 10-4 C m-2 is sufficient to make horizontal magnetic components clearly show up at the whole time duration of seismic waves. When |Qsc| increases, the contribution of surface-charge density to coseismic EM signals becomes more and more dominant comparing with that of the seismically induced streaming-current. We estimate the Qsc expected at the Earth's surface might be a value between -5 × 10-4 and -0.1 C m-2 by the comparison between numerical results and field observations. The vertical magnetic signals only accompany the late-arriving seismic waves, because they are theoretically only induced by SH wave. The field observation results of vertical magnetic signals may be resulted from the scattering effect or the seismic dynamo effect. We conclude that electrokinetic effect combined with surface-charge assumption is one possible generation mechanism of the observed coseismic EM signals.

Ren, Hengxin; Wen, Jian; Huang, Qinghua; Chen, Xiaofei



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

SciTech Connect

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.

Krause, T.R.; Tarman, B.



Electrokinetic behavior of two touching inhomogeneous biological cells and colloidal particles: Effects of multipolar interactions  

E-print Network

Electrokinetic behavior of two touching inhomogeneous biological cells and colloidal particles inhomogeneous colloidal particles and biological cells. These inhomogeneous particles are treated as graded ones Identification and analysis of cell populations and (micro) biological particles are essential in many practical

Huang, Ji-Ping


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

NASA Astrophysics Data System (ADS)

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

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



Electrokinetic Power Generation from Liquid Water Microjets  

SciTech Connect

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

Duffin, Andrew M.; Saykally, Richard J.



Effects of ammonioalkyl sulfonate internal salts on electrokinetic micropump performance and reversed-phase high-performance liquid chromatographic separations.  


Ammonioalkyl sulfonate internal salts are explored owing to their potential for improving electrokinetic pumps used to perform miniaturized HPLC separations. The internal salts investigated can be added at high molarity since they are net-neutral, and furthermore show potential for increasing electroosmotic pumping owing to their large positive dielectric increment. Streaming potential measurements of buffered aqueous systems with varying concentrations of ammonioalkyl sulfonate internal salts have been used to measure these dielectric increments, which increase with the length of the alkyl linker. Due to their positive dielectric increments and their decremental effect on solution conductivity, all of the measured species are predicted to improve the pressure generation (up to 85%) and efficiency performance (up to 140%) of electrokinetic pumps when added at 1 M concentration. RP-HPLC separations with an ammonioalkyl sulfonate (TMAPS) have been performed and indicate that separation performance is essentially unaffected by these species. These results indicate the potential for a variety of ammonioalkyl sulfonates to be used to improve electrokinetic pump performance for miniaturized HPLC. PMID:14604111

Reichmuth, David S; Kirby, Brian J




Microsoft Academic Search

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




Analytical modeling of electrokinetic effect on thermal transport in electrolytic flow in microchannels  

Microsoft Academic Search

A fundamental understanding of electrolytic flow in micro and nano channels is essential for the design of microfluidic devices. In this paper, an analytical investigation is carried out to study the behavior of the electrostatic potential developed at the microchannel surface with the electrokinetic distance and zeta potential. The present work also deals with finding an analytical expression for the

Abhishek Jain; Michael K. Jensen



Electrokinetic delivery of persulfate to remediate PCBs polluted soils: Effect of injection spot.  


Persulfate-based in situ chemical oxidation (ISCO) is a promising technique for the remediation of organic compounds contaminated soils. Electrokinetics (EK) provides an alternative method to deliver oxidants into the target zones especially in low permeable-soil. In this study, the flexibility of delivering persulfate by EK to remediate polychlorinated biphenyls (PCBs) polluted soil was investigated. 20% (w/w) of persulfate was injected at the anode, cathode and both electrodes to examine its transport behaviors under electrical field, and the effect of field inversion process was also evaluated. The results showed that high dosage of persulfate could be delivered into S4 section (near cathode) by electroosmosis when persulfate was injected from anode, 30.8% of PCBs was removed from the soil, and the formed hydroxyl precipitation near the cathode during EK process impeded the transportation of persulfate. In contrast, only 18.9% of PCBs was removed with the injection of persulfate from cathode, although the breakthrough of persulfate into the anode reservoir was observed. These results indicated that the electroosmotic flow is more effective for the transportation of persulfate into soil. The addition of persulfate from both electrodes did not significantly facilitate the PCBs oxidation as well as the treatment of electrical field reversion, the reinforced negative depolarization function occurring in the cathode at high current consumed most of the oxidant. Furthermore, it was found that strong acid condition near the anode favored the oxidation of PCBs by persulfate and the degradation of PCBs was in consistent with the oxidation of Soil TOC in EK/persulfate system. PMID:25193794

Fan, Guangping; Cang, Long; Fang, Guodong; Qin, Wenxiu; Ge, Liqiang; Zhou, Dongmei



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

NASA Astrophysics Data System (ADS)

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.

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



Heterogeneous Surface Charge Enhanced Micromixing for Electrokinetic Flows  

E-print Network

in microfluidic technologies. Critical to a host of applications ranging from DNA hybridization to cytometric limiting the effectiveness of mixers based on parallel lamination for electrokinetic applications.10

Erickson, David


Effect of soil chemical properties on the remediation of phenanthrene-contaminated soil by electrokinetic-Fenton process.  


The electrokinetic-Fenton (EK-Fenton) remediation of soil contaminated with phenanthrene was studied. Two different soils were chosen to investigate the effects of chemical properties, such as Fe oxide contents and acid soil buffer capacity. The H(2)O(2) concentrations in pore water, the electrical potential distributions and the electrical currents were monitored to assess the electrochemical effect in relation to the soil properties. Hadong caly had high acid buffer capacity, and thus the amount of electroosmotic flow was lager in the experiment with Hadong clay than with EPK kaolin. The major mechanism of phenanthrene removal was a degradation in the experiment with EPK Kaolin, while it was a simple transport away from the system in experiment with Hadong clay. It was mainly because of the lower acid buffering capacity and better H(2)O(2) stability in case with EPK Kaolin than with Hadong clay. PMID:16310828

Kim, Jung-Hwan; Han, Sang-Jae; Kim, Soo-Sam; Yang, Ji-Won



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

Microsoft Academic Search

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

Ahmet Altin; Mustafa Degirmenci



Electrokinetic Microfluidic Systems  

NASA Astrophysics Data System (ADS)

Microfabrication technology has enabled the application of electrokinetics as a method of performing chemical analyses and achieving liquid pumping in electronically-controlled microchip systems with no moving parts. Electrokinetics involves the interaction of solid surfaces, ionic solutions, and electric fields. Electric fields can be used to generate bulk fluid motion (electroosmosis) and to separate charged species (electrophoresis). Microfabrication technology has enabled the application of electrokinetics as a method of performing chemical analyses and achieving liquid pumping in electronically-controlled microsystems with no moving parts. This seminar reviews progress at Stanford including methods for sample stacking in capillary electrophoresis assays and fundamental studies of electrokinetic flow instabilities. Field amplified sample stacking (FASS) leverages conductivity gradients as a robust method of increasing sample concentration prior to electrophoretic separation. A major challenge to achieving robust, high-efficiency FASS is the role of electrokinetic instabilities (EKI) generated by a coupling of electric fields and ionic conductivity gradients. This coupling results in electric body forces in the bulk liquid that can generate instabilities. Suppression and/or control of electrokinetic flow instabilities is critical as they dramatically increase dispersion rates and thereby limit stacking efficiency. We have identified the key physical mechanisms in EKI; developed generalized models for electrokinetic systems; and validated the models with experiments. We have applied this understanding to the development of chip systems that achieve signal increases of more than 20,000 fold using FASS. This stacking ratio is over 200 times larger than previous on-chip FASS devices.

Santiago, Juan



Electrokinetic pumps and actuators  

SciTech Connect

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

Phillip M. Paul



Hybrid electrokinetic manipulation in high-conductivity media†  

PubMed Central

This study reports a hybrid electrokinetic technique for label-free manipulation of pathogenic bacteria in biological samples toward medical diagnostic applications. While most electrokinetic techniques only function in low-conductivity buffers, hybrid electrokinetics enables effective operation in high-conductivity samples, such as physiological fluids (~1 S m?1). The hybrid electrokinetic technique combines short-range electrophoresis and dielectrophoresis, and long-range AC electrothermal flow to improve its effectiveness. The major technical hurdle of electrode instability for manipulating high conductivity samples is tackled by using a Ti–Au–Ti sandwich electrode and a 3-parallel-electrode configuration is designed for continuous isolation of bacteria. The device operates directly with biological samples including urine and buffy coats. We show that pathogenic bacteria and biowarfare agents can be concentrated for over 3 orders of magnitude using hybrid electrokinetics. PMID:21487576

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



An electrokinetic pressure sensor  

Microsoft Academic Search

A new concept for a micro pressure sensor is demonstrated. The pressure difference between the inlet and the outlet of glass nanochannels is obtained by measuring the electrokinetically generated electric potential. To demonstrate the proposed concept, experimental investigations are performed for 100 nm wide nanochannels with sodium chloride solutions having various concentrations. The proposed pressure sensor is able to measure

Dong-Kwon Kim; Duckjong Kim; Sung Jin Kim



Electrokinetic micropumps for microfluidics  

Microsoft Academic Search

We have designed and fabricated novel electrokinetic micropumps for producing unidirectional flows in microchannels. These pumps utilize very small voltages (15 Volts) to create significant flow velocities (100 microns\\/s). Low voltages reduce the problem of electrolysis and bubble formation inside the microchannels. One type of the pump is based on DC electroosmosis and requires a DC voltage drop across a

Gaurav Soni



Electrokinetic decontamination of concrete  

Microsoft Academic Search

Concrete structures which have been contaminated with uranium and other radioisotopes may be decontaminated using in-situ electrokinetic remediation. By placing an electrode cell on the concrete surface and using the concrete`s rebar, a ground rod, or another surface cell as the counter electrode, the radioisotopes may be migrated from the concrete into this cell. The process is highly dependent upon

H. L. Lomasney; V. Yachmenev



Electrokinetic decontamination of concrete  

Microsoft Academic Search

The US Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes




Electrokinetic improvement of offshore foundations  

NASA Astrophysics Data System (ADS)

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.

Micic, Silvana


Integrated Electrokinetics-Adsorption Remediation of Saline-Sodic Soils: Effects of Voltage Gradient and Contaminant Concentration on Soil Electrical Conductivity  

PubMed Central

In this study, an integrated in situ remediation technique which couples electrokinetics with adsorption, using locally produced granular activated carbon from date palm pits in the treatment zones that are installed directly to bracket the contaminated soils at bench-scale, is investigated. Natural saline-sodic clay soil, spiked with contaminant mixture (kerosene, phenol, Cr, Cd, Cu, Zn, Pb, and Hg), was used in this study to investigate the effects of voltage gradient, initial contaminant concentration, and polarity reversal rate on the soil electrical conductivity. Box-Behnken Design (BBD) was used for the experimental design and response surface methodology (RSM) was employed to model, optimize, and interpret the results obtained using Design-Expert version 8 platform. The total number of experiments conducted was 15 with voltage gradient, polarity reversal rate, and initial contaminant concentration as variables. The main target response discussed in this paper is the soil electrical conductivity due to its importance in electrokinetic remediation process. Responses obtained were fitted to quadratic models whose R2 ranges from 84.66% to 99.19% with insignificant lack of fit in each case. Among the investigated factors, voltage gradient and initial contaminant concentration were found to be the most significant influential factors. PMID:24459439

Essa, Mohammed Hussain; Mu'azu, Nuhu Dalhat



Electrokinetic focusing and filtration of cells in a serpentine microchannel.  


Focusing cells into a single stream is usually a necessary step prior to counting and separating them in microfluidic devices such as flow cytometers and cell sorters. This work presents a sheathless electrokinetic focusing of yeast cells in a planar serpentine microchannel using dc-biased ac electric fields. The concurrent pumping and focusing of yeast cells arise from the dc electrokinetic transport and the turn-induced acdc dielectrophoretic motion, respectively. The effects of electric field (including ac to dc field ratio and ac field frequency) and concentration (including buffer concentration and cell concentration) on the cell focusing performance were studied experimentally and numerically. A continuous electrokinetic filtration of E. coli cells from yeast cells was also demonstrated via their differential electrokinetic focusing in a serpentine microchannel. PMID:20216971

Church, Christopher; Zhu, Junjie; Wang, Gaoyan; Tzeng, Tzuen-Rong J; Xuan, Xiangchun



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

SciTech Connect

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

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



Analysis of electrokinetic effects on the liquid flow in rectangular microchannels  

Microsoft Academic Search

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

Chun Yang; Dongqing Li



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

SciTech Connect

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

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



Colloidal particle deposition from electrokinetic flow in a microfluidic channel.  


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

Unni, Harikrishnan Narayanan; Yang, Chun




EPA Science Inventory

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


Enhancing Clinical Trials by Incorporating Side Effects  

ERIC Educational Resources Information Center

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

Schrag, Francis




Technology Transfer Automated Retrieval System (TEKTRAN)

The various effects of introduction of chelating agents during electrokinetic remediation of clay soil contaminated with uranium (VI) in pilot scale electrokinetic tests are reported. The combination of the DC electric field (0.7~1.8 V/cm) and citric acid (an inexpensive and environmentally benign c...


Electrokinetic transport in microchannels with random roughness  

SciTech Connect

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

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



Electrokinetic induced solute dispersion in porous media; pore network modeling  

NASA Astrophysics Data System (ADS)

Electrokinetic flow plays an important role in remediation process, separation technique, and chromatography. The solute dispersion is a key parameter to determine transport efficiency. In this study, we present the electrokinetic effects on solute dispersion in porous media at the pore scale, using a pore network model. The analytical solution of the electrokinetic coupling coefficient was obtained to quantity the fluid flow velocity in a cylinder capillary. The effect of electrical double layer on the electrokinetic coupling coefficient was investigated by applying different ionic concentration. By averaging the velocity over cross section within a single pore, the average flux was obtained. Applying such single pore relationships, in the thin electrical double layer limit, to each and every pore within the pore network, potential distribution and the induced fluid flow was calculated for the whole domain. The resulting pore velocities were used to simulate solute transport within the pore network. By averaging the results, we obtained the breakthrough curve (BTC) of the average concentration at the outlet of the pore network. Optimizing the solution of continuum scale advection-dispersion equation to such a BTC, solute dispersion coefficient was estimated. We have compared the dispersion caused by electrokinetic flow and pure pressure driven flow under different Peclet number values. In addition, the effect of microstructure and topological properties of porous media on fluid flow and solute dispersion is presented, mainly based on different pore coordination numbers.

Li, Shuai; Schotting, Ruud; Raoof, Amir



Induced-charge electrokinetic phenomena  

E-print Network

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. ...

Bazant, Martin Z.


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


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

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




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...



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 ...


Electrokinetic micropumps for microfluidics  

NASA Astrophysics Data System (ADS)

We have designed and fabricated novel electrokinetic micropumps for producing unidirectional flows in microchannels. These pumps utilize very small voltages (15 Volts) to create significant flow velocities (100 microns/s). Low voltages reduce the problem of electrolysis and bubble formation inside the microchannels. One type of the pump is based on DC electroosmosis and requires a DC voltage drop across a serpentine wire. This serpentine shaped wire is located at the bottom of a microchannel. Application of a DC potential drop produces induced charges close to the wire surface. Induced charge moves under the influence of local electric field produced by the DC voltage. The serpentine wire is based on the design reported by Gagnon et al., 05.

Soni, Gaurav



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


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

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



Electrokinetics over liquid/liquid interfaces  

NASA Astrophysics Data System (ADS)

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.

Squires, Todd M.



Acoustically and Electrokinetically Driven Transport in Microfluidic Devices  

NASA Astrophysics Data System (ADS)

Electrokinetically driven flows are widely employed as a primary method for liquid pumping in micro-electromechanical systems. Mixing of analytes and reagents is limited in microfluidic devices due to the low Reynolds number of the flows. Acoustic excitations have recently been suggested to promote mixing in the microscale flow systems. Electrokinetic flows through straight microchannels were investigated using the Poisson-Boltzmann and Nernst-Planck models. The acoustic wave/fluid flow interactions in a microchannel were investigated via the development of two and three-dimensional dynamic predictive models for flows with field couplings of the electrical, mechanical and fluid flow quantities. The effectiveness and applicability of electrokinetic augmentation in flexural plate wave micropumps for enhanced capabilities were explored. The proposed concept can be exploited to integrate micropumps into complex microfluidic chips improving the portability of micro-total-analysis systems along with the capabilities of actively controlling acoustics and electrokinetics for micro-mixer applications. Acoustically excited flows in microchannels consisting of flexural plate wave devices and thin film resonators were considered. Compressible flow fields were considered to accommodate the acoustic excitations produced by a vibrating wall. The velocity and pressure profiles for different parameters including frequency, channel height, wave amplitude and length were investigated. Coupled electrokinetics and acoustics cases were investigated while the electric field intensity of the electrokinetic body forces and actuation frequency of acoustic excitations were varied. Multifield analysis of a piezoelectrically actuated valveless micropump was also presented. The effect of voltage and frequency on membrane deflection and flow rate were investigated. Detailed fluid/solid deformation coupled simulations of piezoelectric valveless micropump have been conducted to predict the generated time averaged flow rates. Developed coupled solid and fluid mechanics models can be utilized to integrate flow-through sensors with microfluidic chips.

Sayar, Ersin


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


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

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



Electrokinetic Transport in Ionic Liquids  

E-print Network

A key difficulty in understanding electrokinetic transport in ionic liquids lies in the construction of an appropriate reference dynamics. The common assumption of modelling ion dynamics as a Langevin process is not warranted for solvent-free ionic liquids. The electrokinetic transport of ionic liquids obtained by coarse graining a simple exclusion process defined on a lattice is considered. The resulting dynamical equations can be written as a gradient flow with a degenerate mobility function. This form of the mobility function gives rise to charging behaviours that are different to the ones known in electrolytic solutions; the predicted behaviours agree qualitatively with the phenomenology observed in simulations.

Lee, Alpha A; Goriely, Alain



Electrokinetic high pressure hydraulic system  


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

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



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


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

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



Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part I: Acidbase equilibria and pH buffersx  

E-print Network

Basic principles of electrolyte chemistry for microfluidic electrokinetics. Part I: Acid of electrolytes, and discuss the effects of ionic strength and temperature on pH calculation. More practically, we with electrolyte dynamics and electrochemistry in typical microfluidic electrokinetic systems. Introduction

Santiago, Juan G.


Electrokinetically pumped high pressure sprays  


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

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



Electrokinetically pumped high pressure sprays  


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

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



Electrokinetic ion transport through unsaturated soil:. 2. Application to a heterogeneous field site  

NASA Astrophysics Data System (ADS)

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% (m 3 m -3). Specially designed ceramic-cased electrodes maintained a steady-state moisture content and electric potential field between the electrodes during the field demonstration. Acetate, a byproduct of acetic acid neutralization of the cathode electrolysis reaction, was transported from the cathode to the anode by electromigration. Field demonstration results indicated preferential transport of acetate through soil layers exhibiting higher moisture content/electrical conductivity. These field transport results agree with theoretical predictions that electromigration velocity is proportional to a power function of the effective moisture content. A numerical model using a homogeneous moisture content/electrical conductivity domain did not adequately predict the acetate field results. Numerical model predictions using a three-layer electrical conductivity/moisture content profile agreed qualitatively with the observed acetate distribution. These results suggest that field heterogeneities must be incorporated into electrokinetic models to predict ion transport at the field-scale.

Mattson, Earl D.; Bowman, Robert S.; Lindgren, Eric R.



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


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

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



Analysis of electrokinetic sedimentation of dredged Welland River sediment.  


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

Mohamedelhassan, E; Shang, J Q



Electrokinetic confinement of axonal growth for dynamically configurable neural networks  

PubMed Central

Axons in the developing nervous system are directed via guidance cues, whose expression varies both spatially and temporally, to create functional neural circuits. Existing methods to create patterns of neural connectivity in vitro use only static geometries, and are unable to dynamically alter the guidance cues imparted on the cells. We introduce the use of AC electrokinetics to dynamically control axonal growth in cultured rat hippocampal neurons. We find that the application of modest voltages at frequencies on the order of 105 Hz can cause developing axons to be stopped adjacent to the electrodes while axons away from the electric fields exhibit uninhibited growth. By switching electrodes on or off, we can reversibly inhibit or permit axon passage across the electrodes. Our models suggest that dielectrophoresis is the causative AC electrokinetic effect. We make use of our dynamic control over axon elongation to create an axon-diode via an axon-lock system that consists of a pair of electrode `gates' that either permit or prevent axons from passing through. Finally, we developed a neural circuit consisting of three populations of neurons, separated by three axon-locks to demonstrate the assembly of a functional, engineered neural network. Action potential recordings demonstrate that the AC electrokinetic effect does not harm axons, and Ca2+ imaging demonstrated the unidirectional nature of the synaptic connections. AC electrokinetic confinement of axonal growth has potential for creating configurable, directional neural networks. PMID:23314575

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



Effect of H(2)SO(4) and HCl in the anode purging solution for the electrokinetic-Fenton remediation of soil contaminated with phenanthrene.  


The Electrokinetic-Fenton (EK-Fenton) process is a powerful technology to remediate organic-contaminated soil. The behavior of salts and acids introduced for the pH control has significant influence on the H(2)O(2) stabilization and destruction of organic contaminants. In this study, the effects of the type and concentration of acids, which were introduced at the anode, were investigated for the treatment of clayey soil contaminated with phenanthrene. In experiments with H(2)SO(4) as the anode solution, H(2)O(2) concentration in the anode reservoir decreased due to reaction between reduced species of sulfate and H(2)O(2), as time elapsed. By contrast, HCl as an electrolyte in the anode reservoir did not decrease the H(2)O(2) concentration in the anode reservoir. The reaction between the reduced species of sulfate and H(2)O(2) hindered the stabilization of H(2)O(2) in the soil and anode reservoir. In experiments with HCl for pH control, Cl(.), and Cl(2)(. -), which could be generated with mineral catalyzed Fenton-like reaction, did not significantly hinder H(2)O(2) stabilization. H(2)O(2) transportation with electro-osmotic flow and mineral catalyzed Fenton-like reaction on the soil surface resulted in the simultaneous transport and degradation of phenanthrene, which are dependent of the advancement rate of the acid front and electro-osmotic flow toward the cathode according to HCl and H(2)SO(4) concentrations in the anode purging solution. PMID:19847701

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



Electrokinetic flow focusing and valveless switching integrated with electrokinetic instability for mixing enhancement  

Microsoft Academic Search

This study performs an experimental investigation into electrokinetically-driven flow phenomena in microfluidic chips. The study commences by investigating the electrokinetic focusing\\/valveless switching of multiple sample flows in an M × N microfluidic chip, where M is the number of sample streams and N is the number of outlet channels. The experimental results show that the sample flows can be electrokinetically

Yu-Jen Pan; Chen-Ming Ren; Ruey-Jen Yang



AC Electrokinetics Facilitated Biosensor Cassette for Rapid Pathogen Identification  

PubMed Central

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

Ouyang, Mengxing; Mohan, Ruchika; Lu, Yi; Liu, Tingting; Mach, Kathleen E.; Sin, Mandy L. Y.; McComb, Mason; Joshi, Janhvi; Gau, Vincent



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

SciTech Connect

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




Incorporating Hillslope Effects Into the Geomorphologic Instantaneous Unit Hydrograph  

NASA Astrophysics Data System (ADS)

Use of gamma distributions of stream holding times, rather than the traditional exponential distributions, results in geomorphologic instantaneous unit hydrographs (GIUHs) that better fit data-based IUHs. In this paper, hillslope effects are incorporated into the gamma GIUH (GGIUH) model by assuming that the hillslope travel distance in an area of a given order is approximated by the inverse of twice the local drainage density and introducing a hillslope velocity term. A method of moments fitting procedure is developed to estimate the channel and hillslope velocity terms in the GGIUH model from the moments of rainfall input and basin discharge output. It was found that hillslope velocities are 2 orders of magnitude smaller than channel velocities. The values found for the latter are reasonable given the range of values given in the literature for channel velocities. Similarly, the hillslope velocity term found by the method of moments procedure matches macropore velocities reported in the literature.

van der Tak, Laurens D.; Bras, Rafael L.



Investigation of Electrokinetic Decontamination of Concrete  

Microsoft Academic Search

Experiments have been conducted to investigate the capabilities of electrokinetic decontamination of conceret. Batch equilibration studies have determined that the loading of cesium and strontium on concrete may be decreased using electrolyte solutions containing competing cations, while solubilization of uranium and cobalt, that precipitate at high pH, will require lixiviants containing complexing agents. Dynamic electrokinetic experiments showed greater mobility of

D. W. DePaoli; M. T. Harris; I. L. Morgan; M. R. Ally



Investigation of electrokinetic decontamination of concrete  

Microsoft Academic Search

Experiments have been conducted to investigate the capabilities of electrokinetic decontamination of concrete. Batch equilibration studies have determined that the loading of cesium and strontium on concrete may be decreased using electrolyte solutions containing competing cations, while solubilization of uranium and cobalt, that precipitate at high pH, will require lixiviants containing complexing agents. Dynamic electrokinetic experiments showed greater mobility of

D. W. DePaoli; M. T. Harris; I. L. Morgan; M. R. Ally



Modeling the Electrokinetic Decontamination of Concrete  

Microsoft Academic Search

The decontamination of concrete is a major concern in many Department of Energy (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

Michael T. Harris; David W. DePaoli; Moonis R. Ally



Electrokinetic dewatering of a phosphate clay  

Microsoft Academic Search

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

J. Q. Shang; K. Y. Lo



Nonlinear free vibration of piezoelectric nanobeams incorporating surface effects  

NASA Astrophysics Data System (ADS)

In this study, the nonlinear free vibration of piezoelectric nanobeams incorporating surface effects (surface elasticity, surface tension, and surface density) is studied. The governing equation of the piezoelectric nanobeam is derived within the framework of Euler-Bernoulli beam theory with the von Kármán geometric nonlinearity. In order to satisfy the balance conditions between the nanobeam bulk and its surfaces, the component of the bulk stress, ?zz, is assumed to vary linearly through the nanobeam thickness. An exact solution is obtained for the natural frequencies of a simply supported piezoelectric nanobeam in terms of the Jacobi elliptic functions using the free vibration mode shape of the corresponding linear problem. Then, the influences of the surface effects and the piezoelectric field on the nonlinear free vibration of nanobeams made of aluminum and silicon with positive and negative surface elasticity, respectively, have been studied for various properties of the piezoelectric field, various nanobeam sizes and amplitude ratios. It is observed that if the Young’s modulus of a nanobeam is lower, the effect of the piezoelectric field on the frequency ratios (FRs) of the nanobeam will be greater. In addition, it is seen that by increasing the nanobeam length so that the nanobeam cross section is set to be constant, the surface effects and the piezoelectric field with negative voltage values increases the FRs, whereas it is the other way around when the nanobeam cross section is assumed to be dependent on the length of the nanobeam.

Hosseini-Hashemi, Shahrokh; Nahas, Iman; Fakher, Mahmood; Nazemnezhad, Reza



Integration of electrokinetics and chemical oxidation for the remediation of creosote-contaminated clay.  


Remediation of clayey soils that are contaminated with polycyclic aromatic hydrocarbons (PAHs) is a challenging task that may require integration of several technologies. The benefits of integrating in situ electrokinetic remediation with chemical oxidation were evaluated in laboratory-scale experiments lasting for 8 weeks. A voltage gradient of 48 V/m of direct current and 4.7 V/m of alternating current and periodic additions of chemical oxidants were applied to creosote-contaminated soil. Electrokinetically enhanced oxidation with sodium persulphate resulted in better PAH removal (35%) than either electrokinetics (24%) or persulphate oxidation (12%) alone. However, the improvement was shown only within 1/3 (5 cm) of the soil compartment. Electrokinetics did not improve the performance of Fenton oxidation. Both chemical oxidants created more positive oxidation-reduction potential than electrokinetic treatment alone. On the other hand, persulphate treatment impaired the electroosmotic flow rate. Elemental analyses showed reduction in the natural Al and Ca concentrations, increase in Zn, Cu, P and S concentrations and transfer of several metal cations towards the cathode. In conclusion, the results encourage to further optimisation of an integrated remediation technology that combines the beneficial effects of electrokinetics, persulphate oxidation and Fenton oxidation. PMID:17112659

Isosaari, P; Piskonen, R; Ojala, P; Voipio, S; Eilola, K; Lehmus, E; Itävaara, M



Incorporation of Source Material: The Effect of Instruction  

ERIC Educational Resources Information Center

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

Storch, Neomy



The effect of temperature, irradiance and animal size on incorporation rates of Simocephalus vetulus  

Microsoft Academic Search

Carbon incorporation rates of Simocephalus vetulus were measured to study the effects of the physical state of the animals, size of the animal, varying temperature and light conditions. Physical state of the animal showed little effect on incorporation rates after the first hour. Incorporation rates increased in proportion to the third power of animal size. Experimental animals collected at temperatures

L. Bevan; D. G. Wallen; J. M. Winner



Determination of allantoin in biofluids using micellar electrokinetic capillary chromatography  

Microsoft Academic Search

A micellar electrokinetic chromatographic method is described for the determination and quantitation of allantoin, an end-product of purine metabolism in mammals that is applicable to biofluids of different mammal species and man. The method was optimised following a study on the effect of pH and sample preparation procedure. Final conditions were 30 mM sodium tetraborate, pH 9.5, 75 mM sodium

Luwiza N Alfazema; Sian Howells; David Perrett



Enhancing the Efficiency of Electrokinetic Remediation through Technology Integration  

NASA Astrophysics Data System (ADS)

Remediation or cleanup of soils and groundwater polluted by heavy metals remains a challenge in the field of geo-environmental engineering. Many sites, like ore dressing plants, electroplating plants and battery factories may be polluted by heavy metals. In addition, some natural factors like metal deposits or abundant metal mines, hot springs and volcanic eruptions may also cause heavy metal pollutions. Unlike organic pollutants, heavy metals do not decay naturally, and active approaches to remediation are generally necessary. Although electrokinetic method is considered to be the only technique that is highly-perspective for in situ remediation of heavy metals, and numerous bench-scale studies as well as a few pilot scale experiments illustrated its applicability, this technique has not yet been widely used in practice due to the low efficiencies and/or unacceptable long remediation periods. To enhance the total efficiency of electrokinetic remediation, a systematic approach by integrating different technologies is proposed. This systematic approach includes 1) on-site quick mapping for screening out localized pollution areas, characterizing chemical composition of polluted soils, and for examining the progress of in situ remediation; 2) electrical resistivity tomography(ERT) or electrical resistivity imaging(ERI) for predicting geological structure and hydrogeological boundaries conditions of a polluted site, and for optimizing parameters like voltage and current density for an effective remediation; 3) the use of solar energy to increase flexibility in and applicability of electrokinetic technique; 4) combination with large scale modeling tests for a pertinent evaluation of the feasibility related to electrokinetic remediation for a given soil type taken from a specific polluted site; 5) combination with risk-assessment method to determine feasible cleanup levels; and 6) recovery of heavy metals deposited on electrode plates for possible use as resources. Feasibilities of the proposed systematic approach are illustrated through practical examinations.

Zhang, M.; Komai, T.



Cosolvent-enhanced electrokinetic remediation of soils contaminated with phenanthrene  

SciTech Connect

This research was carried out to evaluate feasibility of using an electrokinetic technique to remove hydrophobic organic pollutants from soils, with the assistance of a cosolvent (n-butylamine, tetrahydrofuran, or acetone) added to the conducting fluid. The experiments were carried out on glacial till clay with phenanthrene as the test compound. Desorption equilibrium was investigated by batch tests. The electrokinetic experiments were conducted using a 19.1 cm long x 6.2 cm inside diameter column under controlled voltage. Water or 20% (volume) cosolvent solution was constantly supplied at the anode. The concentration of phenanthrene in the effluent collected at the cathode was monitored. Each experiment lasted for 100 to 145 days. Results showed that the presence of n-butylamine significantly enhanced the desorption and electrokinetic transport of phenanthrene; about 43% of the phenanthrene was removed after 127 days or 9 pore volumes. The effect of acetone was not as significant as butylamine. The effluent flow in the tetrahydrofuran experiments was minimal, and phenanthrene was not detected in the effluent. The use of water as the conducting solution did not cause observable phenanthrene migration.

Li, A.; Cheung, K.A.; Reddy, K.R.




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...


Numerical simulation of electrokinetically driven micro flows  

E-print Network

to control mixed electroosmotic/pressure driven flow in the grooved micro-channel. The controlled flow pattern enables entrapment and release of prescribed amounts of scalar species in the grooves. As another application, hydrodynamic/ electrokinetic focusing...

Hahm, Jungyoon



Demonstrating Chemical and Analytical Concepts in the Undergraduate Laboratory Using Capillary Electrophoresis and Micellar Electrokinetic Chromatography  

NASA Astrophysics Data System (ADS)

This paper describes instrumental analysis laboratory exercises that utilize capillary electrophoresis and micellar electrokinetic chromatography to demonstrate several analytical and chemical principles. Alkyl parabens (4-hydroxy alkyl benzoates), which are common ingredients in cosmetic formulations, are separated by capillary electrophoresis. The electrophoretic mobilities of the parabens can be explained on the basis of their relative size. 3-Hydroxy ethylbenzoate is also separated to demonstrate the effect of substituent position on the acid dissociation constant and the effect this has on electrophoretic mobility. Homologous series of alkyl benzoates and alkyl phthalates (common plasticizers) are separated by micellar electrokinetic chromatography at four surfactant concentrations. This exercise demonstrates the separation mechanism of micellar electrokinetic chromatography, the concept of chromatographic phase ratio, and the concepts of micelle formation. A photodiode array detector is used in both exercises to demonstrate the advantages and limitations of the detector and to demonstrate the effect of pH and substituent position on the spectra of the analytes.

Palmer, Christopher P.



Electrokinetic investigations of solid/organic liquid dispersions: Effects of temperature treatment of the solid and alkyl chain length of adsorbed amines  

SciTech Connect

Zeta potential of two oxides TiO{sub 2} and Al{sub 2}O{sub 3}, dispersed in various organic solvents were measured at room temperature. The inorganic particles were dried at temperatures ranging from 100 to 500{degree}C for several days and were allowed to cool under vacuum just before use. Electrokinetic investigations of TiO{sub 2} particles in n-alkylamine-hexane solutions with various amine chain lengths (C{sub n}H{sub 2n+1}NH{sub 2}, n=1{endash}10) were also done and allowed the determination of the shear plane position in the eventual electric double layer surrounding the solid surface. Furthermore, in order to estimate the thickness {delta} of the electrical double layer surrounding the solid surface, DLVO theory was applied to TiO{sub 2} particles dispersed in n-hexane, in the presence of butylamine. {copyright} {ital 1996 American Institute of Physics.}

Jada, A.; Siffert, B.; Eleli-Letsango, J. [Centre de Recherches sur la Physico-Chimie des Surfaces Solides 24, avenue du President Kenedy 68200 MULHOUSE (France)



Electrokinetic instability in microchannels  

NASA Astrophysics Data System (ADS)

The effect of geometric confinement on electroconvective instability due to nonequilibrium electro-osmotic slip at the interface of an electrolytic fluid and charge-selective solid is studied. It is shown that the topology of the marginal stability curves and the behavior of the critical parameters depend strongly on both channel geometry and dimensionless Debye length at low voltages for sufficiently deep channels, corresponding to the Rubinstein-Zaltzman instability mechanism, but that stability is governed almost entirely by channel depth for narrow channels at higher voltages. For shallow channels, it is shown that above a transition threshold, determined by both channel depth and Debye length, the low-voltage instability is completely suppressed.

Schiffbauer, Jarrod; Demekhin, Evgeny A.; Ganchenko, Georgy



Electrokinetics of Polar Liquids in Contact with Non-Polar Surfaces  

E-print Network

Zeta potentials of several polar protic (water, ethylene glycol, formamide) as well as polar aprotic (dimethyl sulfoxide) liquids were measured in contact with three non-polar surfaces using closed-cell electro-osmosis. The test surfaces were chemisorbed monolayers of alkyl siloxanes, fluoroalkyl siloxanes and polydimethylsiloxanes (PDMS) grafted on glass slides. All these liquids exhibited substantial electrokinetics in contact with the non-polar surfaces with these observations: the electrokinetic effect on the fluorocarbon-coated surface is the strongest; and on a PDMS grafted surface, the effect is the weakest. Even though these hygroscopic liquids contain small amounts of water, the current models of charging based on the adsorption of hydroxide ions at the interface or the dissociation of preexisting functionalities (e.g., silanol groups) appear to be insufficient to account for the various facets of the experimental observations. The results illustrate how ubiquitous the phenomenon of electro-kinetics ...

Lin, Chih-Hsiu; Chaudhury, Manoj K



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

ERIC Educational Resources Information Center

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

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



Induced-Charge Electrokinetic Phenomena: Theory and Microfluidic Applications  

Microsoft Academic Search

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

Martin Z. Bazant; Todd M. Squires



Incorporating Teacher Effectiveness into Teacher Preparation Program Evaluation  

ERIC Educational Resources Information Center

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

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



Incorporating conservation zone effectiveness for protecting biodiversity in marine planning.  


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

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



Electrokinetic treatment of hazardous wastes in soil and groundwater  

SciTech Connect

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).

Loo, W.W. [Environment & Technology Services, San Francisco, CA (United States)



Electrokinetic particle aggregation patterns in microvortices due to particle-field interaction  

E-print Network

Electrokinetic particle aggregation patterns in microvortices due to particle-field interaction effects. The focusing of the particles into bands is shown to obey negative diffusion dynamics of a long and aggregation dynamics at microflow condi- tions with negligible particle and fluid inertia. These excep- tions

Chang, Hsueh-Chia



Microsoft Academic Search

A simple and rapid capillary micellar electrokinetic chromatography (MEKC) method was developed for the separation and determination of ephedrine, gastrodin and ligustrazin in tetraborate buffer by direct UV detection at 200 nm. The effect of separation voltage, the concentration of sodium dodecyl sulfate (SDS) and the buffer pH value on separation was optimized and the following conditions was selected: 20

R. Y. Wang; W. Y. Ma; D. Y. Chen




Microsoft Academic Search

A ?-cyclodextrin (?-CD) modified micellar electrokinetic capillary chromatographic (CD-MEKC) method has been developed to separate PAH metabolites. Baseline resolution of six acidic PAH metabolites was achieved within 14 min. The effects of several separation parameters were investigated in detail. These were the ?-CD concentration, sodium dodecyl sulfate (SDS) concentration, pH of the buffer, organic modifier, and urea concentration. The apparent

Xin Xu; Robert J. Hurtubise



Nonlinear electrokinetic flow about a polarized conducting drop.  


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

Schnitzer, Ory; Yariv, Ehud



Fabrication and Characterization of Jute Fiber-Reinforced PET Composite: Effect of LLDPE Incorporation  

Microsoft Academic Search

The aim of the research was to study the effect of LLDPE incorporation in the jute fiber-reinforced PET composites (50% fiber by wt). The effect of LLDPE incorporation into PET was investigated by measuring the mechanical properties of the LLDPE blended jute fiber-reinforced PET composites. LLDPE was blended (20-80% by wt) with PET and the thin films were made by

Tanzina Huq; Avik Khan; Nazia Noor; M. Saha; Ruhul A. Khan; Mubarak A. Khan; M. Mushfequr Rahman; K. Mustafizur Tahman




PubMed Central

In this article we consider a semiparametric generalized mixed-effects model, and propose combining local linear regression, and penalized quasilikelihood and local quasilikelihood techniques to estimate both population and individual parameters and nonparametric curves. The proposed estimators take into account the local correlation structure of the longitudinal data. We establish normality for the estimators of the parameter and asymptotic expansion for the estimators of the nonparametric part. For practical implementation, we propose an appropriate algorithm. We also consider the measurement error problem in covariates in our model, and suggest a strategy for adjusting the effects of measurement errors. We apply the proposed models and methods to study the relation between virologic and immunologic responses in AIDS clinical trials, in which virologic response is classified into binary variables. A dataset from an AIDS clinical study is analyzed. PMID:20160899

Liang, Hua



Effect of melt composition on Bi incorporation in iron garnets  

NASA Astrophysics Data System (ADS)

The saturation temperature, the growth rate and the crystal composition of rare-earth iron garnet films grown from a PbO?Bi 2O 3?B 2O 3 flux were investigated. The concentrations of the garnet component oxides, the proportions of the flux oxides, B 2O 3 and Bi 2O 3, and the ratio Fe 2O 3/RE 2O 3 in the melt were systematically varied to determine their effect. The melts generally obey Van Erk's theory of solubility and growth rate. However, an increase of either the B or Bi concentration in the melt linearly decreases the rare earth activity, which results in an increase in both the garnet solubility and the effective segregation coefficient of Bi into growing garnet films. Using the rare earth activity calculated from solubility data, a Bi segregation coefficient of 0.0010 is observed that is independent of melt composition and growth temperature.

Fratello, V. J.; Licht, S. J.; Norelli, M. P.



Electrokinetics of pure clay minerals revisited  

Microsoft Academic Search

Clay minerals have long attracted the attention of colloid scientists. This paper considers, specifically, their important role in the transport of various contaminants from land to sea, e.g., metal ions and organic detrital and man-made material in watercourses. Advance in experimental techniques have enabled precise characterization of clays and then electrokinetic experiments at high electrolyte concentrations, such as in seawater.

I. Sondi; J. Biscan; V. Pravdic



Electrokinetics of Pure Clay Minerals Revisited  

Microsoft Academic Search

Clay minerals have long attracted the attention of colloid scientists. This paper considers, specifically, their important role in the transport of various contaminants from land to sea, e.g., metal ions and organic detrital and man-made material in watercourses. Advances in experimental techniques have enabled precise characterization of clays and then electrokinetic experiments at high electrolyte concentrations, such as in seawater.

Ivan Sondi; Jasenka Biš?an; Velimir Pravdi?



Opto-electrokinetic manipulation technique for highperformance  

SciTech Connect

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

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



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

NASA Astrophysics Data System (ADS)

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

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



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

SciTech Connect

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

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



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


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

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



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


We discuss the electrostatic contribution to the elastic moduli of a cell or artificial membrane placed in an electrolyte and driven by a DC electric field. The field drives ion currents across the membrane, through specific channels, pumps or natural pores. In steady state, charges accumulate in the Debye layers close to the membrane, modifying the membrane elastic moduli. We first study a model of a membrane of zero thickness, later generalizing this treatment to allow for a finite thickness and finite dielectric constant. Our results clarify and extend the results presented by D. Lacoste, M. Cosentino Lagomarsino, and J.F. Joanny (EPL 77, 18006 (2007)), by providing a physical explanation for a destabilizing term proportional to [see formula in text] in the fluctuation spectrum, which we relate to a nonlinear (E(2)) electrokinetic effect called induced-charge electro-osmosis (ICEO). Recent studies of ICEO have focused on electrodes and polarizable particles, where an applied bulk field is perturbed by capacitive charging of the double layer and drives the flow along the field axis toward surface protrusions; in contrast, we predict "reverse" ICEO flows around driven membranes, due to curvature-induced tangential fields within a nonequilibrium double layer, which hydrodynamically enhance protrusions. We also consider the effect of incorporating the dynamics of a spatially dependent concentration field for the ion channels. PMID:19184149

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



Nonlinear electrokinetic phenomena in microfluidic devices  

NASA Astrophysics Data System (ADS)

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.

Ben, Yuxing


Effectively incorporating selected multimedia content into medical publications  

PubMed Central

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



Pore network model of electrokinetic transport through charged porous media  

NASA Astrophysics Data System (ADS)

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

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



Pore network model of electrokinetic transport through charged porous media.  


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

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



The effect of dopant incorporation on the elastic properties of Ti metal  

NASA Astrophysics Data System (ADS)

The effect of dopant atoms on the structural and elastic properties of ? titanium is examined through the use of density functional theory. The effect of 66 dopant atoms, from H through the third row transition metal elements, were considered in this study. In all cases the dopant concentration was approximately 3 at%, with substitutional incorporation investigated for all atoms considered and interstitial incorporation investigated for a smaller subset of elements. Interstitial incorporation was calculated to be more energetically favourable for the elements H, B to F, S and Cl with these dopants coordinating octahedrally with the surrounding Ti atoms, while substitutional incorporation was found to be more stable for the other elements. The five independent single crystal elastic constants are calculated, along with the bulk and shear moduli. The energetics and mechanically stability associated with the alloying of various dopants is also discussed.

Wilson, N. C.; McGregor, K.; Gibson, M. A.; Russo, S. P.



AC Electrokinetics of Physiological Fluids for Biomedical Applications.  


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

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



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

Microsoft Academic Search

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

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



Improving electrokinetic microdevice stability by controlling electrolysis bubbles.  


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

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



Ion Irradiation Effects in Synthetic Garnets Incorporating Actinides Satoshi Utsunomiya1  

E-print Network

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

Utsunomiya, Satoshi


Electrokinetically induced flocculation of Enteroaggregative Escherichia coli  

NASA Astrophysics Data System (ADS)

Enteroaggregative Escherichia coli (EAEC) is a diarrheal microbe, whose aggregative dynamics is involved in its pathogenic behavior. We investigated EAEC's electrokinetic response in miniaturized and microfluidic devices. We found a novel response of the microbe under low magnitude, uniform and oscillating electric fields. In this electrokinetically induced response, microbial adhesion to a glass substrate decreases significantly, leading to a loss of EAEC's biofilm forming abilities. Some earlier studies had indicated that that microbial adhesion and detachment at surfaces can be prompted only by charge-transfer processes at the electrode and not applied electrical potentials - such an inference is not corroborated by our work. Instead, we found that electric fields promote the formation of large mesoscopic microbial aggregations (flocs) in the solution. The presence of frequency dependent relaxation phenomena is explored and the observed results are extended to other microbes.

Kumar, Aloke; Mortensen, Ninell; Harris, Mansueta; Mukherjee, Partha; Retterer, Scott; Doktycz, Mitchel



Electrokinetic properties of the mammalian tectorial membrane  

PubMed Central

The tectorial membrane (TM) clearly plays a mechanical role in stimulating cochlear sensory receptors, but the presence of fixed charge in TM constituents suggests that electromechanical properties also may be important. Here, we measure the fixed charge density of the TM and show that this density of fixed charge is sufficient to affect mechanical properties and to generate electrokinetic motions. In particular, alternating currents applied to the middle and marginal zones of isolated TM segments evoke motions at audio frequencies (1–1,000 Hz). Electrically evoked motions are nanometer scaled (?5–900 nm), decrease with increasing stimulus frequency, and scale linearly over a broad range of electric field amplitudes (0.05–20 kV/m). These findings show that the mammalian TM is highly charged and suggest the importance of a unique TM electrokinetic mechanism. PMID:23440188

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



Electrokinetic Characterization of 'Tunable Colloidal Crystals'  

NASA Astrophysics Data System (ADS)

We present complementary electrokinetic measurements (electrophoresis, dielectric spectroscopy, and conductivity) on fluorescently labeled and sterically stabilized poly(methyl methacrylate) spheres suspended in near density matching solvents with dielectric constants between 6 and 8. The results are compared with confocal microscopy observations of the same particle suspensions, some of which exhibited low volume fraction (? < 0.01) crystal structure. Conductivity was measured as a function of volume fraction to determine the particle charge using the standard electrokinetic model. The addition of quaternary ammonium salts was used to screen charge (reducing long range particle interaction) and to induce a charge reversal as determined by electrophoresis. The dielectric constant showed significant low frequency relaxation indicating the presence of association structures, e.g. inverse micelles, formed following sample sonocation.

Hollingsworth, Andrew; Russel, William; Chaikin, Paul; Leunissen, Mirjam; van Blaaderen, Alfons



In situ soil remediation using electrokinetics  

SciTech Connect

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

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



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


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

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



Water-quality effects of incorporating poultry litter into perennial grassland soils.  


Poultry litter provides a rich source of nutrients for perennial forages, but the usual practice of surface-applying litter to pastures can degrade water quality by allowing nutrients to be transported from fields in surface runoff, while much of the NH4-N volatilizes. Incorporating litter into the soil can minimize such problems in tilled systems, but has not been used for perennial forage systems. In this study, we minimized disturbance of the crop, thatch, and soil structure by using a knifing technique to move litter into the root zone. Our objective was to determine effects of poultry litter incorporation on quantity and quality of runoff water. Field plots were constructed on a silt loam soil with well-established bermudagrass [Cynodon dactylon (L.) Pers.] and mixed grass forage. Each plot had 8 to 10% slopes, borders to isolate runoff, and a downslope trough with sampling pit. Poultry litter was applied (5.6 Mg ha(-1)) by one of three methods: surface-applied, incorporated, or surface-applied on soil-aeration cuts. There were six treatment replications and three controls (no litter). Nutrient concentrations and mass losses in runoff from incorporated litter were significantly lower (generally 80-95% less) than in runoff from surface-applied litter. By the second year of treatment, litter-incorporated soils had greater rain infiltration rates, water-holding capacities, and sediment retention than soils receiving surface-applied litter. Litter incorporation also showed a strong tendency to increase forage yield. PMID:14674565

Pote, D H; Kingery, W L; Aiken, G E; Han, F X; Moore, P A; Buddington, K



Decontamination of radioactive concrete using electrokinetic technology  

Microsoft Academic Search

The experimental results of the electrokinetic decontamination with 0.01 M of nitric acid were that the cesium ions were removed\\u000a by up to 52% from the concrete after 15 days, also the cobalt ions were only removed by up to 0.7%. The concrete should be\\u000a washed with H2SO4 as a pretreatment before electrokintic decontamination to lower its pH below 4.0. The removal

Gye-Nam Kim; Wang-Kyu Choi; Kune-Woo Lee



A novel microfluidic driver via AC electrokinetics.  


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

Kuo, Ching-Te; Liu, Cheng-Hsien



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

PubMed Central

The efficacy of controlling Meloidogyne hapla on potato with water incorporation of ethoprop was compared to physical incorporation before planting. The standard practice of aldicarb application for insect control was also evaluated for M. hapla suppression with and without ethoprop. Physical incorporation before planting by rototilling or discing reduced (P ? 0.05) tuber infection. Postplant water incorporation of ethoprop was not as effective as physical incorporation of ethoprop or postplant water incorporation of aldicarb and did not reduce (P ? 0.05) tuber infection at harvest. Ethoprop did not affect yield, whereas aldicarb increased yield in one experiment. PMID:19283186

Ingham, Russell E.; Morris, Mark; Newcomb, Gene B.




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...


Electrokinetic focusing and filtration of cells in a serpentine microchannel  

Microsoft Academic Search

Focusing cells into a single stream is usually a necessary step prior to counting and separating them in microfluidic devices such as flow cytometers and cell sorters. This work presents a sheathless electrokinetic focusing of yeast cells in a planar serpentine microchannel using dc-biased ac electric fields. The concurrent pumping and focusing of yeast cells arise from the dc electrokinetic

Christopher Church; Junjie Zhu; Gaoyan Wang; Tzuen-Rong J. Tzeng; Xiangchun Xuan



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...


Cosolvent-enhanced electrokinetic remediation of soils contaminated with phenanthrene  

Microsoft Academic Search

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

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



Field Implementation of Electrokinetic-ISCO Remediation  

NASA Astrophysics Data System (ADS)

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

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



Effects of Estradiol on Incorporation of New Cells in the Developing Zebra Finch Song System: Potential  

E-print Network

Effects of Estradiol on Incorporation of New Cells in the Developing Zebra Finch Song System masculiniza- tion of the zebra finch song system are unclear; both es- tradiol and sex-specific genes may males than females. Four studies on zebra finches were conducted using bromo- deoxyuridine (Brd

Wade, Juli


Incorporating psychosocial characteristics in cost-effectiveness modelling of Type 1 diabetes  

E-print Network

Incorporating psychosocial characteristics in cost-effectiveness modelling of Type 1 diabetes Unit of Diabetes, Endocrinology and Metabolism, School of Medicine and Biomedical Sciences, University education programme that aims to teach individuals with Type 1 diabetes to change their self-care behaviours

Oakley, Jeremy


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

ERIC Educational Resources Information Center

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

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



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

E-print Network

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

Montes-Hernandez, German


Author's personal copy Selenium incorporation into calcite and its effect on crystal growth: An atomic force  

E-print Network

Author's personal copy Selenium incorporation into calcite and its effect on crystal growth December 2012 Accepted 29 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


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

ERIC Educational Resources Information Center

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

Hodge, David R.



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

PubMed Central

Background Cost-effectiveness analyses (CEAs) that use patient-specific data from a randomized controlled trial (RCT) are popular, yet such CEAs are criticized because they neglect to incorporate evidence external to the trial. A popular method for quantifying uncertainty in a RCT-based CEA is the bootstrap. The objective of the present study was to further expand the bootstrap method of RCT-based CEA for the incorporation of external evidence. Methods We utilize the Bayesian interpretation of the bootstrap and derive the distribution for the cost and effectiveness outcomes after observing the current RCT data and the external evidence. We propose simple modifications of the bootstrap for sampling from such posterior distributions. Results In a proof-of-concept case study, we use data from a clinical trial and incorporate external evidence on the effect size of treatments to illustrate the method in action. Compared to the parametric models of evidence synthesis, the proposed approach requires fewer distributional assumptions, does not require explicit modeling of the relation between external evidence and outcomes of interest, and is generally easier to implement. A drawback of this approach is potential computational inefficiency compared to the parametric Bayesian methods. Conclusions The bootstrap method of RCT-based CEA can be extended to incorporate external evidence, while preserving its appealing features such as no requirement for parametric modeling of cost and effectiveness outcomes. PMID:24888356



Electrokinetic Hydrogen Generation from Liquid WaterMicrojets  

SciTech Connect

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

Duffin, Andrew M.; Saykally, Richard J.



Practical aspects of in-situ electrokinetic extraction  

SciTech Connect

Electrokinetic extraction in an emerging technology that can be used to remove contaminants from heterogeneous fine-grained soils in situ. Contaminants in the subsurface are removed by the application of a direct-current electric field across the contaminated soil. The primary contaminant transport and removal mechanisms are electroosmotic advection and ionic migration. However, there are many complex physicochemical reactions occurring simultaneously during the process that may enhance or retard the cleanup process. Nonetheless, the viability of the technology has been established by results obtained from many bench-scale and large-scale laboratory and pilot-scale field experiments performed on various soils. This paper will review the fundamental concepts of the technology and discuss some important practical aspects and design criteria of the technology for field implementations. An example on cost analysis of the technology is also presented to demonstrate the use of various equations presented in the paper and to illustrate the cost-effectiveness of the technology.

Alshawabkeh, A.N. [Northeastern Univ., Boston, MA (United States). Dept. of Civil and Environmental Engineering] [Northeastern Univ., Boston, MA (United States). Dept. of Civil and Environmental Engineering; Yeung, A.T. [Binnie Black and Veatch Hong Kong Ltd., Shatin (Hong Kong)] [Binnie Black and Veatch Hong Kong Ltd., Shatin (Hong Kong); Bricka, M.R. [Army Corps of Engineers, Vicksburg, MS (United States). Waterways Experiment Station] [Army Corps of Engineers, Vicksburg, MS (United States). Waterways Experiment Station



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


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

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




Microsoft Academic Search

A simple, accurate, and rapid capillary micellar electrokinetic chromatography method was developed for the determination of gastrodin in rat blood. All experiments were performed in a 47?cm (40?cm effective length)?×?75??m i.d. uncoated fused-silica capillary with UV detection at 200?nm. A running buffer composed of 50?mM sodium tetraborate, 15?mM sodium dodecyl sulfate (SDS) (pH=9.50) was found to be suitable. The method

Rongying Wang; Hua Fan; Wanyun Ma



Is the Societal Approach Wide Enough to Include Relatives?: Incorporating Relatives' Costs and Effects in a Cost-Effectiveness Analysis  

Microsoft Academic Search

It is important for economic evaluations in healthcare to cover all relevant information. However, many existing evaluations fall short of this goal, as they fail to include all the costs and effects for the relatives of a disabled or sick individual. The objective of this study was to analyse how relatives' costs and effects could be measured, valued and incorporated

Thomas Davidson; Lars-Åke Levin



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

E-print Network

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

Bazant, Martin Z.


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

SciTech Connect

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

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



Effects of carbon incorporation on doping state of YBa 2Cu 3O y  

Microsoft Academic Search

Effects of carbon incorporation on the doping state of YBa2Cu3Oy (Y-123) were investigated. Quantitative carbon analysis revealed that carbon could be introduced into Y-123 from both the precursor and the sintering gas. Nearly carbon-free (<200ppm) samples were prepared from a vacuum-treated precursor by sintered at 900°C and cooling with 20°C\\/min in flowing oxygen gas. The lower Tc (=88K) and higher

A. Yamamoto; K. Hirose; Y. Itoh; T. Kakeshita; S. Tajima



Flexible polymer photovoltaic modules with incorporated organic bypass diodes to address module shading effects  

Microsoft Academic Search

We present experimental results on large-area low-cost processed flexible organic photovoltaic (OPV) modules incorporating organic bypass diodes to eliminate the negative effects of shading on the module power output. A fully organic-based structure (organic solar module combined with an organic bypass diode) is essential to allow monolithic interconnection of the bypass diode during the solar module production within the same

Roland Steim; Pavel Schilinsky; Stelios A. Choulis; Christoph J. Brabec



Faceted design of channels for low-dispersion electrokinetic flows in microfluidic systems.  


A novel methodology for designing microfluidic channels for low-dispersion, electrokinetic flows is presented. The technique relies on trigonometric relations that apply for ideal electrokinetic flows, allowing faceted channels to be designed using common drafting software and a hand calculator. Flows are rotated and stretched along the abrupt interface between adjacent regions having differing specific permeability--a quantity with dimensions of length that we introduce to derive the governing equations. Two-interface systems are used to eliminate hydrodynamic rotation of bands injected into channels. Regions bounded by interfaces form faceted flow "prisms" with uniform velocity fields that can be combined with other prisms to obtain a wide range of turning angles and expansion ratios. Lengths of faceted prisms can be varied arbitrarily, simplifying chip layout and allowing the ability to reduce unwanted effects such as transverse diffusion and Joule heating for a given faceted prism. Designs are demonstrated using two-dimensional numerical solutions of the Laplace equation. PMID:14674450

Fiechtner, Gregory J; Cummings, Eric B



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

PubMed Central

This study reports a multifunctional electrode approach which directly implements electrokinetic enhancement on a self-assembled-monolayer-based electro-chemical sensor for point-of-care diagnostics. Using urinary tract infections as a model system, we demonstrate that electrokinetic enhancement, which involves in situ stirring and heating, can enhance the sensitivity of the strain specific 16S rRNA hybridization assay for 1 order of magnitude and accelerate the time-limiting incubation step with a 6-fold reduction in the incubation time. Since the same electrode platform is used for both electrochemical signal enhancement and electrochemical sensing, the multifunctional electrode approach provides a highly effective strategy toward fully integrated lab-on-a-chip systems for various biomedical applications. PMID:22397486

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



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


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

Javaid, Arshad; Shafique, Sobiya; Shafique, Shazia



Electrokinetic trapping at the one nanometer limit  

PubMed Central

Anti-Brownian electrokinetic traps have been used to trap and study the free-solution dynamics of large protein complexes and long chains of DNA. Small molecules in solution have thus far proved too mobile to trap by any means. Here we explore the ultimate limits on trapping single molecules. We developed a feedback-based anti-Brownian electrokinetic trap in which classical thermal noise is compensated to the maximal extent allowed by quantum measurement noise. We trapped single fluorophores with a molecular weight of < 1 kDa and a hydrodynamic radius of 6.7 ? for longer than one second, in aqueous buffer at room temperature. This achievement represents an 800-fold decrease in the mass of objects trapped in solution, and opens the possibility to trap and manipulate any soluble molecule that can be fluorescently labeled. To illustrate the use of this trap, we studied the binding of unlabeled RecA to fluorescently labeled single-stranded DNA. Binding of RecA induced changes in the DNA diffusion coefficient, electrophoretic mobility, and brightness, all of which were measured simultaneously and on a molecule-by-molecule basis. This device greatly extends the size range of molecules that can be studied by room temperature feedback trapping, and opens the door to further studies of the binding of unmodified proteins to DNA in free solution. PMID:21562206

Fields, Alexander P.; Cohen, Adam E.



Effect of membrane incorporation of 1-palmitoylcarnitine on surface charge of human erythrocytes.  


1-Palmitoylcarnitine (1-PC) reduced the electrophoretic mobility of human erythrocytes bathed in low ionic strength solution. Unlike divalent cations which appear to reduce electrophoretic mobility by screening surface negative charge, cationic 1-PC does so by being incorporated into the plasma membrane. Incorporation of 1-PC was assessed directly by measurement of the partition coefficients which are 1.18 x 10(5) and 1.38 x 10(5) in sarcoplasmic reticulum vesicles and erythrocyte ghosts, respectively. The hydrophobic nature of the amphiphile interaction with erythrocyte membrane was also evident as an antihemolytic effect at 1-PC concentrations that also reduced electrophoretic mobility. Moreover, the potency and efficacy of acylcarnitines to reduce electrophoretic mobility increased as the acyl chain length increased. 1-PC also reduced the electrophoretic mobility of guinea-pig ventricular myocytes in low ionic strength solution. Estimation of the zeta potential yielded positive shifts of 4 mV in myocytes and 5 mV on erythrocytes at 1 microM 1-PC. These voltage shifts are essentially the same as those reported for activation and inactivation of sodium and calcium currents in myocytes. Therefore, the surface charge effect of 1-PC depends upon membrane incorporation and underlies the electrophysiological actions of the amphiphile including arrhythmias. PMID:8263958

Gruver, C; Pappano, A J



Effect of fluoride on glucose incorporation and metabolism in biofilm cells of Streptococcus mutans.  


The aim of this study was two-fold: firstly, to study the effect of high fluoride concentrations on carbohydrate metabolism in Streptococcus mutans present in biofilms on hydroxyapatite; and, secondly, to evaluate the effect of fluoride-bound hydroxyapatite on lactic acid formation in growing biofilms of Strep. mutans. Biofilms of a clinical strain of Strep. mutans on saliva-coated hydroxyapatite beads were incubated with sodium fluoride over a wide range of concentrations. At high fluoride concentrations (>10 mM) the incorporation of [14C]-labeled glucose decreased by 80-85%, at both pH 7.0 and 5.6. At lower fluoride concentrations, the effect of fluoride on the incorporation of labeled glucose was pH-dependent in both biofilm cells and in planktonic cells. At pH 7.0, fluoride at concentrations < 10 mM had little or no effect. Pretreatment of hydroxyapatite discs with fluoride varnish (Fluor Protector) or fluoride solutions caused a statistically significant reduction of lactic acid formation in associated, growing biofilms of Strep. mutans. Fluoride varnish and 0.2% (47.6 mM) sodium fluoride solution exhibited a statistically significant inhibitory effect on lactate production. PMID:11456349

Balzar Ekenbäck, S; Linder, L E; Sund, M L; Lönnies, H




EPA Science Inventory

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



EPA Science Inventory

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


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

PubMed Central

We studied the effect of solar radiation on the incorporation of [(sup3)H]thymidine ([(sup3)H]TdR) and [(sup14)C]leucine ([(sup14)C]Leu) by bacterioplankton in a high mountain lake and the northern Adriatic Sea. After short-term exposure (3 to 4 h) of natural bacterial assemblages to sunlight just beneath the surface, the rates of incorporation of [(sup3)H]TdR and [(sup14)C]Leu were reduced at both sites by up to (symbl)70% compared to those for the dark control. Within the solar UV radiation (290 to 400 nm), the inhibition was caused exclusively by UV-A radiation (320 to 400 nm). However, photosynthetically active radiation (PAR) (400 to 700 nm) contributed almost equally to this effect. Experiments with samples from the high mountain lake showed that at a depth of 2.5 m, the inhibition was caused almost exclusively by UV-A radiation. At a depth of 8.5 m, where chlorophyll a concentrations were higher than those in the upper water column, the rates of incorporation of [(sup3)H]TdR were higher in those samples exposed to full sunlight or to UV-A plus PAR than in the dark control. In laboratory experiments with artificial UV light, the incorporation of [(sup3)H]TdR and [(sup14)C]Leu by mixed bacterial lake cultures was also inhibited mainly by UV-A. In contrast, in the presence of the green alga Chlamydomonas geitleri at a chlorophyll a concentration of 2.5 (mu)g liter(sup-1), inhibition by UV radiation was significantly reduced. These results suggest that there may be complex interactions among UV radiation, heterotrophic bacteria, and phytoplankton and their release of extracellular organic carbon. Our findings indicate that the wavelengths which caused the strongest inhibition of TdR and Leu incorporation by bacterioplankton in the water column were in the UV-A range. However, it may be premature to extrapolate this effect to estimates of bacterial production before more precise information on how solar radiation affects the transport of TdR and Leu into the cell is obtained. PMID:16535724

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



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

E-print Network

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

Park, Namkyoo


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

NASA Astrophysics Data System (ADS)

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.

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



Fluorescent probe studies of mixed micelles of phospholipids and bile salts. Effect of cholesterol incorporation.  


The binding of the fluorescent alkylamines, N-(2-aminoethyl)-5-dimethyl-amino-1-naphthalene sulfonamide, N-(5-aminopentyl)-5-dimethylamino-1-naphthalene sulfonamide (dansyl cadaverine) and N-(10-aminodecyl)-5-dimethylamino-1-napthalene sulfonamide with phospholipid and phospholipid-deoxycholate micelles, has been shown to increase with the length of the alkyl spacer chain. The probes bind more effectively to micelles containing unsaturated phospholipids and do not interact strongly with bile salt solutions at low concentrations. Cholesterol incorporation into mixed micelles results in a quenching of probe fluorescence due to displacement of probe molecules. The enhanced rigidity of the mixed micelles on solubilizing cholesterol is established by a decrease in pyrene excimer fluorescence and by the less effective perturbation of the micellar structure by 1-anilino-8-naphthalene sulfonate. The anionic probe 1-anilino-8-naphthalene sulfonate is also displaced from the mixed micelles when cholesterol is incorporated, suggesting a dominant role for packing and hydrophobic effects in binding both positively and negatively charged probes. PMID:7370247

Narayanan, R; Paul, R; Balaram, P



Electrokinetic concentration of charged molecules  


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

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




E-print Network

NANOCOMPOSITE CARBON-PDMS THICK ELECTRODES FOR ELECTROKINETIC MANIPULATION DURING CELL FUSION M Carbon-PDMS nanocomposite electrodes (C- PDMS), integrated in PDMS microfluidic systems to carry out electrofusion protocol was also tested. KEYWORDS: Carbon-Polydimethylsiloxane Nanocomposite, Electrokinetics

Paris-Sud XI, Université de


Journal of Power Sources 156 (2006) 677684 Thermodynamic analysis of electrokinetic energy conversion  

E-print Network

conversion Xiangchun Xuan, Dongqing Li Department of Mechanical and Industrial Engineering, University is carried out for electrokinetic energy conversion. We demonstrate that the efficiencies depend solely Elsevier B.V. All rights reserved. Keywords: Electrokinetic energy conversion; Generator; Pump; Figure

Xuan, Xiangchun "Schwann"


Hydrodynamics and electrokinetics in colloidal and microfluidic systems  

NASA Astrophysics Data System (ADS)

The bulk of this thesis investigates the role of hydrodynamic interactions and electrokinetic effects in colloidal and microfluidic systems. We study the influence of a solid wall upon the correlated diffusive motion of two Brownian spheres, and make predictions which agree with experiments performed at the University of Chicago. We examine experiments which had seemed to measure an attractive interaction between similarly-charged colloidal spheres near charged glass walls, and argue that some may have misinterpreted hydrodynamic coupling effects as an attractive equilibrium interaction. Our predictions agree quantitatively with measurements, have withstood further experimental tests, and have re-directed a nearly decade-long debate to whether or not any novel attraction exists, rather than the responsible mechanism responsible. Furthermore, we present a general method for making this non-equilibrium, kinetic interaction (which has no effect on equilibrium systems) effective in steady-state systems, so that layered crystals of like-charged colloids may be grown near walls. We present a new electrokinetic technique ('induced-charge electro-osmosis') for driving a steady microfluidic flow around conducting surfaces using an AC electric field. We present basic theory along with applications, including experiments to measure the surface chemistry and conduction of colloidal particles, and propose microfluidic pumps and mixers which operate without moving parts in AC electric fields. We present an experimental measurement of the electrophoretic mobility of carbon black particles in (non-aqueous) dodecane using heterodyne dynamic light scattering techniques. We find that the surface charge densities are quite small (˜5e/particle), and account for the measured spread in mobilities by assuming Poisson-distributed surface charges. A substantial effort is underway to create cold anti-Hydrogen atoms in order to perform the most stringent tests ever of CPT invariance. Electromagnetic field traps which simultaneously confine both charged and neutral particles are needed for this project. We present an analysis of the motion of a single charged particle in one such trap, identify stable and unstable regions, calculate frequencies and locate resonances. Lastly, we provide an analysis of Slocum and White's proposed MEMS valve whose gap can be controllably reduced down to the nanometer scale.

Squires, Todd Michael


Method and apparatus for electrokinetic transport  

NASA Technical Reports Server (NTRS)

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

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



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

SciTech Connect

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

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



Contrasting effects of arachidonic acid and docosahexaenoic acid membrane incorporation into cardiomyocytes on free cholesterol turnover.  


The preservation of a constant pool of free cholesterol (FC) is critical to ensure several functions of cardiomyocytes. We investigated the impact of the membrane incorporation of arachidonic acid (C20:4 ?6, AA) or docosahexaenoic acid (C22:6 ?3, DHA) as ?6 or ?3 polyunsaturated fatty acids (PUFAs) on cholesterol homeostasis in primary cultures of neonatal rat cardiac myocytes. We measured significant alterations to the phospholipid FA profiles, which had markedly different ?6/?3 ratios between the AA and DHA cells (13 vs. 1). The AA cells showed a 2.7-fold lower cholesterol biosynthesis than the DHA cells. Overall, the AA cells showed 2-fold lower FC masses and 2-fold higher cholesteryl ester masses than the DHA cells. The AA cells had a lower FC to phospholipid ratio and higher triglyceride levels than the DHA cells. Moreover, the AA cells showed a 40% decrease in ATP binding cassette transporter A1 (ABCA1)-mediated and a 19% decrease in ABCG1-mediated cholesterol efflux than the DHA cells. The differences in cholesterol efflux pathways induced by AA or DHA incorporation were not caused by variations in ABCs transporter expression and were reduced when ABC transporters were overexpressed by exposure to LXR/RXR agonists. These results show that AA incorporation into cardiomyocyte membranes decreased the FC turnover by markedly decreasing the endogenous cholesterol synthesis and by decreasing the ABCA1- and ABCG1-cholesterol efflux pathways, whereas DHA had the opposite effects. We propose that these observations may partially contribute to the beneficial effects on the heart of a diet containing a high ?3/?6 PUFA ratio. PMID:25019598

Doublet, Aline; Robert, Véronique; Vedie, Benoît; Rousseau-Ralliard, Delphine; Reboulleau, Anne; Grynberg, Alain; Paul, Jean-Louis; Fournier, Natalie



Implementation of Electrokinetic-ISCO Remediation  

NASA Astrophysics Data System (ADS)

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

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



Elementary framework for cold field emission: Incorporation of quantum-confinement effects  

SciTech Connect

Although the Fowler-Nordheim (FN) equation serves as the foundation of cold field emission theory, it may not be suitable for predicting the emitted current density (ECD) from emitters with a quantum-confined electron supply. This work presents an analytical framework for treating cold field emission from metals that includes the effects of a quantum-confined electron supply. Within the framework, quantum confinement in emitters is classified into transverse and normal quantum confinement based on the orientation of the confinement relative to the emission direction. The framework is used to generate equations predicting the ECD from rectangular and cylindrical emitter geometries comprised of electron supplies of reduced dimensionality. Transverse quantum confinement of the electron supply leads to a reduction in the total ECD as transverse emitter dimensions decrease and normal quantum confinement results in an oscillatory ECD as a function of the normal quantum well width. Incorporating a geometry-dependent field enhancement factor into the model reveals an optimal transverse well width for which quantum confinement of the electron supply and field enhancement equally affect the ECD and a maximum total ECD for the emitter geometry at a given applied field is obtained. As a result, the FN equation over-predicts the ECD from emitters with transverse dimensions under approximately 5?nm, and in those cases, geometry-specific ECD equations incorporating quantum-confinement effects should be employed instead.

Patterson, A. A., E-mail:; Akinwande, A. I. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Microsystems Technology Laboratories, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)



Effects of oxygen incorporation in solar cells with a-SiOx:H absorber layer  

NASA Astrophysics Data System (ADS)

The effects of oxygen incorporation on layer properties and cell performance were investigated in thin film solar cells with a-SiOx:H absorber layers. Besides the widened optical band gap and increased defect densities, a doping effect is observed upon oxygen incorporation even for the layers with wide band gap. From comparison of solar cells illuminated from either p- or n-side, we conclude that overall hole carrier collection is strongly deteriorated by increasing the oxygen concentration. The donor-like states induced by oxygen reform the electric field in the absorber. The intensified electric field near the p/i interface improves the quantum efficiency (QE) around 400 nm, which is attributed to the better carrier collection in the p-layer. The maximum of QE shows a blue shift with both p- and n-side illumination. It is consistent with the enhanced optical band gap of the absorber layer and shows the potential of usage in multi-junction solar cells.

Wang, Shuo; Smirnov, Vladimir; Chen, Tao; Holländer, Bernhard; Zhang, Xiaodan; Xiong, Shaozhen; Zhao, Ying; Finger, Friedhelm



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

NASA Astrophysics Data System (ADS)

A thin calcium phosphate film was synthesized on both commercially pure Ti and Si wafers by electron beam evaporation of hydroxyapatite as an evaporant with simultaneous Ar ion beam bombardments. Silver was introduced into an ion-beam-assisted deposition of a calcium phosphate thin film for antimicrobial effect. The amount of incorporated silver ions was controlled by immersing calcium-phosphate-coated samples in different AgNO3 concentrations, and Rutherford backscattering spectrometry (RBS) was employed to measure the amounts of substituted silver. The higher concentration of silver in the calcium phosphate film was more effective in reducing the bacteria of Escherichia coli ATCC 8739 and Streptococcus mutans OMZ 65 on contact with respect to controls.

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



Determining the Effectiveness of Incorporating Geographic Information Into Vehicle Performance Algorithms  

SciTech Connect

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

Sera White



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

E-print Network

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

Miksik, Ivan


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

SciTech Connect

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

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



Electrokinetic demonstration at the unlined chromic acid pit  

SciTech Connect

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

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



Alternating current electrokinetics enhanced in situ capacitive immunoassay.  


A rapid in situ capacitive immunoassay is presented herein. Conventional immunoassay typically relies on diffusion for transport of analytes in many cases causing long detection time and lack of sensitivity. By integrating alternating current electrokinetics (ACEK) and impedance sensing, this work provides a rapid in situ capacitive affinity biosensing. ACEK induces both fluid flow and particle motion, conveying target molecules toward electrodes immobilized with probes, resulting in rapid enrichment of target molecules and a capacitance change at the ''electrode-fluid'' interface. The benefit of ACEK enhanced immunoassay was demonstrated using the antigen and antibody from Johne's disease (JD) as an example. To clarify the importance of DEP and ACET effects for binding reaction, two different electrode pattern designs for capacitive immunoassay are studied. The asymmetric array and symmetric electrodes exhibit very similar response at lower electric field due to DEP effects, while asymmetric array has remarkable higher response at high-electric field because the convection becomes more important at high field. The disease positive and negative serum samples are distinguished in few minutes. PMID:25258204

Li, Shanshan; Ren, Yukun; Cui, Haochen; Yuan, Quan; Wu, Jie; Eda, Shigetoshi; Jiang, Hongyuan



Effects of Toxic Substances on Natural Bacterial Assemblages Determined by Means of [3H]Thymidine Incorporation  

PubMed Central

The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were examined by means of [3H]thymidine incorporation into trichloroacetic acid-insoluble material. Results from a large number of coastal marine and freshwater samples suggest the following. (i) The effects of the three toxicants included reductions in the bacterial cell number as well as changes in rates of [3H]thymidine incorporation and in [3H]thymidine incorporation per cell. The concentrations that inhibited [3H]thymidine incorporation by 50% ranged from 3 to 11 mg liter?1 for 3,5-dichlorophenol, 6 to 10 mg liter?1 for 2,4-dinitrophenol, and 21 to 123 mg liter?1 for potassium dichromate, with a tendency to higher values in bacterial assemblages from more eutrophic environments. (ii) The effects of 3,5-dichlorophenol and potassium dichromate determined by [3H]leucine incorporation into bacterial protein were similar or larger than those obtained from [3H]thymidine incorporation. (iii) Two to four hours of exposure to the toxicants was necessary before stable maximum effects were found in [3H]thymidine incorporation. (iv) Storage of natural environmental samples should be avoided, since tests with water stored for 1 to 3 days sometimes produced results different from results obtained from in situ tests. (v) The effects of 3,5-dichlorophenol, 2,4-dinitrophenol, and potassium dichromate on natural bacterial assemblages were relatively constant during periods with different growth rates in the assemblages, during various periods of the year, and between samples from freshwater and marine localities. With some precautions, [3H]thymidine incorporation can be used as a quick and sensitive method for determining the effects of toxicants on aquatic bacterial assemblages from natural environmental samples. PMID:16348108

Riemann, Bo; Lindgaard-Jørgensen, Palle



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


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

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



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


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

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



Method for eliminating gas blocking in electrokinetic pumping systems  


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

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



Transport of radioactive ions in soil by electrokinetics  

SciTech Connect

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

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



Electrolysis-reducing electrodes for electrokinetic devices.  


Direct current electrokinetic systems generally require Faradaic reactions to occur at a pair of electrodes to maintain an electric field in an electrolyte connecting them. The vast majority of such systems, e.g. electrophoretic separations (capillary electrophoresis) or electroosmotic pumps (EOPs), employ electrolysis of the solvent in these reactions. In many cases, the electrolytic products, such as H+ and OH? in the case of water, can negatively influence the chemical or biological species being transported or separated, and gaseous products such as O? and H? can break the electrochemical circuit in microfluidic devices. This article presents an EOP that employs the oxidation/reduction of the conjugated polymer poly(3,4-ethylenedioxythiophene), rather than electrolysis of a solvent, to drive flow in a capillary. Devices made with poly(3,4-ethylenedioxythiophene) electrodes are compared with devices made with Pt electrodes in terms of flow and local pH change at the electrodes. Furthermore, we demonstrate that flow is driven for applied potentials under 2?V, and the electrodes are stable for potentials of at least 100?V. Electrochemically active electrodes like those presented here minimize the disadvantage of integrated EOP in, e.g. lab-on-a-chip applications, and may open new possibilities, especially for battery-powered disposable point-of-care devices. PMID:21425174

Erlandsson, Per G; Robinson, Nathaniel D



Microfluidic devices for electrokinetic sample fractionation.  


We present three generations of microchip-based "in-space" sample fractionators and collectors for use in proteomics. The basic chip design consisted of a single channel for CE separation of analytes that then intersects a fractionation zone feed into multiple high aspect ratio microchannels for fractionation of separated components. Achievements of each generation are discussed in relation to important design criteria. CE-separated samples were electrokinetically driven to multiple collection channels in sequence without cross-contamination under the protection of sheath streams. A 36-channel fractionator demonstrated the efficacy of a high-throughput fractionator with no observed cross-contamination. A mixture of IgG and BSA was used to test the efficiency of the fractionator and collector. CE of the fractionated samples was performed on the same device to verify their purity. Our demonstration proved to be efficient and reproducible in obtaining non-contaminated samples over 15 sample injections. Experimental results were found to be in close agreement with PSpice simulation in terms of flow behavior, contamination control and device performance. The design presented here has a great potential to be integrated in proteomic platforms. PMID:20665916

Wang, Zhen; Taylor, Justine; Jemere, Abebaw B; Harrison, D Jed



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

PubMed Central

Background The transfer of new scientific discoveries into healthcare interventions requires that basic and clinical researchers work together with health care providers to generate team science. These innovative models require translational teams, and need to extend beyond the academic environment. The future of translational science requires partnerships with the healthcare community as well as the broader, general community. This new integrated model of effective translational teams holds promise for addressing thorny and persistent health disparities, is consistent with the nation’s strategic priority of eliminating health disparities, and bodes well for increasing healthcare effectiveness aimed at better health for all. Discussion As part of the 13th Research Centers in Minority Institutions (RCMI) International Symposium on Health Disparities, several senior academic leaders joined efforts to hold a workshop to discuss a model that considers the incorporation of two translational research strategies in research career development programs: Comparative effectiveness research (CER) and community-based participatory research (CBPR) for increasing healthcare effectiveness and eliminating healthcare disparities. Discussion included what issues may be most germane to the concept of a unified model for research workforce development through formal training and career development leading to increased effectiveness in healthcare for better health. Summary We believe that there is a gap in knowledge and skills in formal research career development programs that will enable physicians, other clinicians, and basic scientists to actively participate in these two translational research strategies. The purpose of this paper is to share the outcomes of these discussions, and encourage further discussion and possible innovation in the formulation of a new model for translational research workforce development. PMID:25024819



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

SciTech Connect

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

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



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

SciTech Connect

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

Nieves, L.A.



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

NASA Technical Reports Server (NTRS)

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.

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



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

PubMed Central

Current neuroscience has identified several constructs to increase the effectiveness of upper extremity rehabilitation. One is the use of progressive, skill acquisition-oriented training. Another approach emphasizes the use of bilateral activities. Building on these principles, this paper describes the design and feasibility testing of a robotic / virtual environment system designed to train the arm of persons who have had strokes. The system provides a variety of assistance modes, scalable workspaces and hand-robot interfaces allowing persons with strokes to train multiple joints in three dimensions. The simulations utilize assistance algorithms that adjust task difficulty both online and offline in relation to subject performance. Several distinctive haptic effects have been incorporated into the simulations. An adaptive master-slave relationship between the unimpaired and impaired arm encourages active movement of the subject's hemiparetic arm during a bimanual task. Adaptive anti-gravity support and damping stabilize the arm during virtual reaching and placement tasks. An adaptive virtual spring provides assistance to complete the movement if the subject is unable to complete the task in time. Finally, haptically rendered virtual objects help to shape the movement trajectory during a virtual placement task. A proof of concept study demonstrated this system to be safe, feasible and worthy of further study. PMID:19666345

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



Experimental and theoretical basis of electrokinetic phenomena in rock-water systems and its applications to geophysics  

Microsoft Academic Search

The z potentials and the streaming potential coefficients of silicate mineral-water and rock-water systems were measured for purposes of estimating the magnitude of electrokinetic effects induced by water diffusion in the earth's interior. In rock-water systems the adsorption reaction of H+ at a solid surface is proved to be a main factor determining the z potential. For typical crustal rocks

Tsuneo Ishido; Hitoshi Mizutani



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

NASA Astrophysics Data System (ADS)

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.

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



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


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

Khouryieh, H; Aramouni, F



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


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

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



Doping effects on proton incorporation and conduction in SrZrO3.  


The doping effects on the proton incorporation and protonic conductivity of perovskite-type SrZrO3 were investigated using the density functional theory (DFT) with the generalized gradient approximation (GGA). The optimized geometries, formation energies of hydrogen defect and activation energies for hydrogen diffusion in SrZrO3 doped with Al, Sc, Ga, Y, Rh, In, and Yb were calculated. It was shown that the doping leads to large local distortions around hydrogen and dopant ion, affecting the protonic conduction in these oxides. The alignment of hydrogen levels varies with the dopant introduced into the SrZrO3. In In-, Y-, Sc-, Ga-, and Al-doped SrZrO3, the H+ is the lowest energy state in all the bandgap. But for Yb- and Rh-doped SrZrO3, the H+ is the lowest energy state only when the Fermi energy below 2.37 and 2.66 eV, respectively. The estimates of the activation energy show good agreement between the measured and calculated activation energies. Also, the hydrogen diffusion seems to become more difficult as the distance between hydrogen and dopant ion decreases. PMID:16514593

Shi, Chunsheng; Morinaga, Masahiko



The effect of nitrogen incorporation in DLC films deposited by ECR Microwave Plasma CVD  

NASA Astrophysics Data System (ADS)

Diamond like carbon (DLC) and nitrogenated diamond like carbon (DLC:N) films have been deposited by electron cyclotron resonance microwave plasma chemical vapor deposition (ECR-MP CVD) on Si (1 1 0), steel and glass substrates, using CH4 and N2 as plasma source. The effect of nitrogen doping on the optical, electrical, structural and mechanical properties of films was investigated. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy results showed that sp2 bonded carbon phases increased while the sp3 bonded carbon phases decreased by nitrogen doping. Microhardness measurements showed a decrease in hardness (from 75 to 69 GPa) according to nitrogen incorporation. Average transmittance of all the films was over 90% and band gap energy (Eg) of the films decreased due to increasing nitrogen flow rate. The film morphology was studied using the atomic force microscopy (AFM). Electrical properties were characterized by Hall measurement. Undoped DLC was p-type with a conductivity of 9.81 × 10-6 (? cm)-1. DLC films became n-type by nitrogen doping. The best conductivity value for the nitrogen doped DLC films was found 2.77 × 10-5 (? cm)-1. PL spectra of DLC and DLC:N films showed three peaks at 405 nm (3.06 eV), 533 nm (2.32 eV) and 671 nm (1.84 eV).

Seker, Z.; Ozdamar, H.; Esen, M.; Esen, R.; Kavak, H.



Enhancement of the photoresponse in organic field-effect transistors by incorporating thin DNA layers.  


A mechanistic study of the DNA interfacial layer that enhances the photoresponse in n-type field-effect transistors (FET) and lateral photoconductors using a solution-processed fullerene derivative embedded with disperse-red dye, namely PCBDR, is reported. Incorporation of the thin DNA layer simultaneously leads to increasing the electron injection from non-Ohmic contacts into the PCBDR active layer in dark and to increasing the photocurrent under irradiation. Such features lead to the observation of the enhancement of the photoresponsivity in PCBDR FETs up to 10(3) . Kelvin probe microscopy displays that in the presence of the DNA layer, the surface potential of PCBDR has a greater change in response to irradiation, which is rationalized by a larger number of photoinduced surface carriers. Transient absorption spectroscopy confirms that the increase in photoinduced carriers in PCBDR under irradiation is primarily ascribed to the increase in exciton dissociation rates through the PCBDR/DNA interface and this process can be assisted by the interfacial dipole interaction. PMID:24249650

Zhang, Yuan; Wang, Mingfeng; Collins, Samuel D; Zhou, Huiqiong; Phan, Hung; Proctor, Christopher; Mikhailovsky, Alexander; Wudl, Fred; Nguyen, Thuc-Quyen



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


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

Lim, Hayoung A; Draper, Ellary



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


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

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



Effect of Chitosan Incorporation and Scaffold Geometry on Chondrocyte Function in Dense Collagen Type I Hydrogels  

PubMed Central

Tissue engineering approaches for articular cartilage (AC) repair using collagen type I (Coll)-based hydrogels are limited by their low collagen fibril density (CFD; <0.5?wt%) and their poor capacity to support chondrocyte differentiation. Chitosan (CTS) is a well-characterized polysaccharide that mimics the glycosaminoglycans (GAGs) present in native AC extracellular matrix and exhibits chondroprotective properties. Here dense Coll/CTS hydrogel discs (16?mm diameter, 140–250??m thickness) with CFD (?6?wt%) approaching that of AC were developed to investigate the effect of CTS content on the growth and differentiation of three-dimensionally seeded RCJ3.1C5.18 chondroprogenitor cells. Compared to dense Coll alone, cells seeded within Coll/CTS showed increased viability and metabolic activity, as well as a decrease in cell-mediated gel contraction. Immunohistochemistry for collagen type II, in combination with Safranin O staining and GAG quantification, indicated greater chondroprogenitor differentiation within Coll/CTS, compared to cells seeded within Coll alone. The complex interplay between scaffold geometry, microstructure, composition, mechanical properties and cell function was further evaluated by rolling dense planar sheets to prepare cylindrically shaped constructs having clinically relevant diameters (3–5?mm diameter, 9?mm height). The compressive modulus of the cylindrically shaped constructs decreased significantly after 7 days in culture, and remained unchanged up to 21 days for each scaffold composition. Unlike Coll, cells seeded within Coll/CTS showed greater viability along the entire radial extent of the cylindrical rolls and increased GAG production at each time point. While GAG content decreased over time and reduced cell viability was observed within the core region of all cylindrical rolls, the incorporation of CTS diminished both these effects. In summary, these findings provide insight into the challenges involved when scaling up scaffolds designed and optimised in vitro for tissue repair. PMID:23859275

Chicatun, Florencia; Pedraza, Claudio E.; Muja, Naser; Ghezzi, Chiara E.; McKee, Marc D.



Theoretical implications of incorporating relative biological effectiveness into radiobiological equivalence relationships  

PubMed Central

Objective: Earlier radiobiological equivalence relationships as derived for low-linear energy transfer (LET) radiations are revisited in the light of newer radiobiological models that incorporate an allowance for relative biological effectiveness (RBE). Methods: Linear-quadratic (LQ) radiobiological equations for calculating biologically effective dose at both low- and high-LET radiations are used to derive new conditions of equivalence between a variety of radiation delivery techniques. The theoretical implications are discussed. Results: The original (pre-LQ) concept of equivalence between fractionated and continuous radiotherapy schedules, in which the same physical dose is delivered in each schedule, inherently assumed that low-LET radiation would be used in both schedules. LQ-based equivalence relationships that allow for RBE and are derived assuming equal total physical dose between schedules are shown to be valid only in limited circumstances. Removing the constraint of equality of total physical dose allows the identification of more general (and more practical) relationships. Conclusion: If the respective schedules under consideration for equivalence both involve radiations of identical LET, then the original equivalence relationships remain valid. However, if the compared schedules involve radiations of differing LET, then new (and more restrictive) equivalence relationships are found to apply. Advances in knowledge: Theoretically derived equivalence relationships based on the LQ model provide a framework for the design and intercomparison of a wide range of clinical techniques including those involving high- and/or low-LET radiations. They also provide a means of testing for the validity of variously assumed tissue repair kinetics. PMID:23385996

Dale, R G



Micellar electrokinetic capillary chromatography of limonoid glucosides from citrus seeds  

Microsoft Academic Search

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

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



Capillary electrokinetic separations: Influence of mobile phase composition on performance  

SciTech Connect

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

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




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...


Effect of mode of incorporation of disintegrants on the characteristics of fluid-bed wet-granulated tablets.  


A full factorial experimental design was employed to investigate the effects of mode of disintegrant incorporation and concentration in wet-granulated paracetamol tablets manufactured by top-spray fluid-bed. Disintegrants (croscarmellose sodium, sodium starch glycolate, or crospovidone) were incorporated either intragranularly, extragranularly, or distributed equally between the two phases. The results were analysed by a general quadratic equation and response surfaces generated. On examining the results for dissolution studies the combined mode resulted in significantly faster dissolution rates than did the extragranular mode which, in turn, was superior to the intragranular mode of inclusion. These results were reflected in the disintegration studies where the combined mode exhibited the shortest disintegration times for all the disintegrants. Tablet crushing strength was not affected by the mode of incorporation of concentration of the disintegrants. Main as well as interaction effects between the types, mode of incorporation and percent disintegrant employed were significant (P < 0.05) for disintegration time and percent release at 15 min. Croscarmellose sodium exhibited the shortest while crospovidone displayed significantly (P < 0.05) longer disintegration times. Formulations containing crospovidone did not meet official compendial (USP XXII) requirements of 80% in 30 min. In general, croscarmellose sodium and sodium starch glycolate were found to be less sensitive to the mode of incorporation than crospovidone. PMID:7901364

Khattab, I; Menon, A; Sakr, A



Electrokinetic control of fluid transport in gold-coated nanocapillary array membranes in hybrid nanofluidic-microfluidic devices.  


The introduction of metallic elements into microfluidic devices that support electrokinetic transport creates several fundamental issues relative to the high conductivity of the metal, which can act as a current shunt, causing profound effects on the transport process. Here we examine the use of Au-coated nanocapillary array membranes (Au NCAMs) as electrically addressable fluid control elements in multi-layer microfluidic architectures. Three alternative methods for fluid injection across Au NCAMs are presented: electrokinetic injection across NCAMs with Au coated on one side (asymmetric NCAM), electrokinetic injection across NCAMs with an embedded Au layer (symmetric NCAM), and field-free electroosmotic flow (EOF) pumping across either type of Au NCAM. Injection efficiency across asymmetric NCAMs depends on the orientation of the asymmetric membrane relative to the driving potential. Efficient injections are enabled when the Au coating is on the receiving side of the membrane, however, some distortion of the injected volume element is observed, especially with large injection potentials. These results for asymmetric membranes agree qualitatively with two-dimensional numerical simulations of injections across a single slit pore, which suggest that the direction-selective transport behavior is related to electrophoretic transport of the anionic fluorescein probe. Reproducible, high quality injections are also achieved in symmetric Au NCAMs having an embedded gold nanoband region within the nanopores. Nanoband Au NCAMs are excellent candidates for a range of applications, including high efficiency electrochemical sensing, electrochemically catalyzed conversion or pretreatment and label free sensing utilizing extraordinary optical transmission. EOF pumping could be an alternative to electrokinetic injections in some applications, however, this approach is only useful for relatively large pore sizes (>400 nm) and presents considerably worse sample spreading via Taylor dispersion. PMID:20445875

Piruska, Aigars; Branagan, Sean P; Minnis, Alexandra B; Wang, Zhen; Cropek, Donald M; Sweedler, Jonathan V; Bohn, Paul W



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

Microsoft Academic Search

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

Joe W. Kotrlik; Heather A. Williams


Synergistic effects of dimethyloxalylglycine and butyrate incorporated into ?-calcium sulfate on bone regeneration.  


Osteogenesis is closely related to angiogenesis, and the combined delivery of angiogenic and osteogenic factors has been suggested to enhance bone regeneration. Small molecules have been explored as alternatives to growth factors for tissue regeneration applications. In this study, we examined the effects of the combined application of angiogenic and osteogenic small molecules on bone regeneration using a prolyl hydroxylase, dimethyloxalylglycine (DMOG), and a histone deacetylase inhibitor, butyrate. In a critical size bone defect model in rats, DMOG and butyrate, which were incorporated into ? calcium sulfate (?CS), resulted in synergistic enhancements in bone and blood vessel formation, eventually leading to bone healing, as confirmed by micro-CT and histological analyses. In MC4 pre-osteoblast cultures, DMOG and butyrate enhanced the pro-angiogenic responses and osteoblast differentiation, respectively, which were evaluated based on the levels of hypoxia inducible factor (HIF)-1? protein and the expression of pro-angiogenic molecules (VEGF, home oxidase-1, glucose transporter-1) and by alkaline phosphatase (ALP) activity and the expression of osteoblast phenotype marker molecules (ALP, ?1(I)col, osteocalcin, and bone sialoprotein). DMOG combined with butyrate synergistically improved osteoblast differentiation and pro-angiogenic responses, the levels of which were drastically increased in the cultures on ?CS disks. Furthermore, it was demonstrated that ?CS increased the level of HIF-1? and as a consequence VEGF expression, and supported osteoblast differentiation through the release of calcium ions from the ?CS. Altogether, the results of this study provide evidence that a combination treatment with the small molecules DMOG and butyrate can expedite the process of bone regeneration and that ?CS can be an efficient delivery vehicle for the small molecules for bone regeneration. PMID:25477166

Woo, Kyung Mi; Jung, Hong-Moon; Oh, Joung-Hwan; Rahman, Saeed Ur; Kim, Soung Min; Baek, Jeong-Hwa; Ryoo, Hyun-Mo



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

E-print Network

Phosphorus incorporation during Si,,001...:P gas-source molecular beam epitaxy: Effects on growth of Physics. DOI: 10.1063/1.2925798 I. INTRODUCTION Phosphorus is a common n-type dopant in Si-based mi desorption TPD , Auger electron spectroscopy AES , and reflection high-energy electron diffraction RHEED

Spila, Timothy P.


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

NASA Technical Reports Server (NTRS)

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

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



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

ERIC Educational Resources Information Center

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…

Roth, Anne I.; Wunderlich, Kenneth W.


Electrokinetic-enhanced bioaugmentation for remediation of chlorinated solvents contaminated clay  

PubMed Central

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

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



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

NASA Astrophysics Data System (ADS)

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

Honegger, Thibault; Peyrade, David



Electrokinetic remediation of six emerging organic contaminants from soil.  


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 10mA. A pH control in the anolyte reservoir (pH>13) at 10mA 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?gmin(-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

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



The effect of aluminum oxide incorporation on the material and electrical properties of hafnium oxide on Ge  

Microsoft Academic Search

Hafnium aluminate thin films were synthesized by atomic layer deposition (ALD) to assess the effect of aluminum oxide incorporation on the dielectric\\/Ge interfacial properties. In these HfxAlyOz thin films, the Hf to Al cation ratio was effectively controlled by changing the ratio of hafnium oxide to aluminum oxide ALD cycles, while their short range order was changed upon increasing aluminum

Monica Sawkar-Mathur; Ya-Chuan Perng; Jun Lu; Hans-Olof Blom; John Bargar; Jane P. Chang



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

Microsoft Academic Search

Hafnium aluminate thin films were synthesized by atomic layer deposition (ALD) to assess the effect of aluminum oxide incorporation on the dielectric\\/Ge interfacial properties. In these HfAl{sub y}O{sub z} thin films, the Hf to Al cation ratio was effectively controlled by changing the ratio of hafnium oxide to aluminum oxide ALD cycles, while their short range order was changed upon

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



Single cell antimicrobial susceptibility testing by confined microchannels and electrokinetic loading  

PubMed Central

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

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



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

NASA Astrophysics Data System (ADS)

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

Thompson, I.; Lear, G.



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

SciTech Connect

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

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



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...


Effect of incorporation of distillers' dried grain with solubles (DDGS) on quality of cornbread  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recent increase in biofuel production creates a sizable stockpile of its co-product in the form of Distiller’s Dried Grain with Solubles (DDGS) that needs to be utilized beyond animal feeds. We evaluated cornbreads, which were formulated incorporating 0, 5, 10, 15, 20, 25, and 30% corn DDGS into co...


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

PubMed Central

Background Immediate recognition of life-threatening conditions and injuries is the key to trauma management. To date, the impact of focused assessment with computed tomography in trauma (FACTT) has not been formally assessed. We aimed to find out whether the concept of using FACTT during primary trauma survey has a negative or positive effect on survival. Methods In a retrospective, multicentre study, we compared our time management and probability of survival (Ps) in major trauma patients who received FACTT during trauma resuscitation with the trauma registry of the German Trauma Society (DGU). FACTT is defined as whole-body computed tomography (WBCT) during primary trauma survey. We determined the probability of survival according to the Trauma and Injury Severity Score (TRISS), the Revised Injury Severity Classification score (RISC) and the standardized mortality ratio (SMR). Results We analysed 4.817 patients from the DGU database from 2002 until 2004, 160 (3.3%) were from our trauma centre at the Ludwig-Maximilians-University (LMU) and 4.657 (96.7%) from the DGU group. 73.2% were male with a mean age of 42.5 years, a mean ISS of 29.8. 96.2% had suffered from blunt trauma. Time from admission to FAST (focused assessment with sonography for trauma)(4.3 vs. 8.7 min), chest x-ray (8.1 vs. 16.0 min) and whole-body CT (20.7 vs. 36.6 min) was shorter at the LMU compared to the other trauma centres (p < 0.001). SMR calculated by TRISS was 0.74 (CI95% 0.40-1.08) for the LMU (p = 0.24) and 0.92 (CI95% 0.84-1.01) for the DGU group (p = 0.10). RISC methodology revealed a SMR of 0.69 (95%CI 0.47-0.92) for the LMU (p = 0.043) and 1.00 (95%CI 0.94-1.06) for the DGU group (p = 0.88). Conclusion Trauma management incorporating FACTT enhances a rapid response to life-threatening problems and enables a comprehensive assessment of the severity of each relevant injury. Due to its speed and accuracy, FACTT during primary trauma survey supports rapid decision-making and may increase survival. PMID:20459713



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

NASA Astrophysics Data System (ADS)

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

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



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

SciTech Connect

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

Pal, N.; Bessman, S.P.



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


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

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



The Effects of Incorporating Classroom Pets into the Fourth Grade Science Curriculum  

NASA Astrophysics Data System (ADS)

The purpose of this study was to identify and promote successful teaching strategies that incorporate classroom pets in order to influence student engagement, achievement, and perceptions of animals. This was a small action research study conducted in a fourth grade science classroom. Both quantitative and qualitative data were obtained including, pre- and post-assessments, student interviews, researcher field notes, researcher journal, and student work. The results of this study revealed an increased academic achievement from the pre- to post-assessment, increased student observations and descriptions when discussing the animals, and increased student empathy toward the animals. The results also revealed that the teacher's incorporation of the animals within the science curriculum grew in ease over time, and that the animals provided the educator with opportunities to teach non-content related lessons and also a concrete experience for the teacher to apply and extend the science content.

Admire, Maegan


Effects of chemical environment on the solubility and incorporation mechanism for hydrogen in olivine  

Microsoft Academic Search

To investigate the solubility and the sites of incorporation of hydrogen in olivine as a function of point defect concentration, two-stage high-temperature annealing experiments have been carried out. The first annealing stage (the dry preannealing stage) was conducted at a total pressure of 0.1 MPa, a temperature of 1300° C and various oxygen fugacities in the range 10-11–10-4 MPa for

Quan Bai; D. L. Kohlstedt



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

SciTech Connect

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

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



Effect of radioactivity on stent-graft incorporation after endovascular treatment of aneurysms: An animal study.  


Poor stent-graft (SG) incorporation into the vessel wall, following endovascular repair of abdominal aortic aneurysms (EVAR), can lead to endoleaks and SG migration. Low-dose radiation can prevent aneurysm recurrence after coil embolization, and has been associated with a "paradoxical" increase in neointima formation after stenting in a few studies. It was hypothesized that in situ beta radiation emitted from SG could improve its incorporation by preventing the persistence of circulating channels between the implant and the vessel wall and increasing neointima formation around the SG. Phosphorus 32 ((32)P, 200 or 400 kBq per SG (n = 6 each)) was ion implanted on the external surface of balloon-expandable SGs. Twelve radioactive and six non-radioactive SGs were deployed in iliac arteries of nine Mongrel dogs. Neointima formation inside the graft and the persistence of circulating flow through an artificial groove created during the endovascular procedure were assessed by follow-up imaging and by blinded, computerized histomorphometric analysis after animal sacrifice at 3 months. Occlusion occurred in four radioactive SGs. A lesser number of patent grooves was observed along high-activity SGs than along control SGs (1/3 versus 4/4). No difference in neointima formation was observed in radioactive and non-radioactive SGs. Alteration of external graft surface was observed after ion implantation. Ion implantation of (32)P on SGs does not seem to be a viable strategy to improve incorporation and prevent type-I endoleak after EVAR. PMID:16958041

Lerouge, Sophie; Raymond, Jean; Schloesser, Klaus; Gaboury, Louis; Soulez, Gilles



Incorporation of \\  

Microsoft Academic Search

After the simultaneous injection of trace amounts of 75Se-seleno- methionine and 35S-methionine into the wing vein of the hen, the extent and mode of incorporation of both amino acids into the egg white proteins was studied. The results obtained appear to indicate that the selenomethionine is incorporated in a manner indistinguishable from that of methionine. All of the 75Se associated



Feasibility of electrokinetic soil remediation in horizontal Lasagna cells.  


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

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



Testing and evaluation of electrokinetic decontamination of concrete  

SciTech Connect

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

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



Separation and determination of podophyllum lignans by micellar electrokinetic chromatography  

Microsoft Academic Search

A micellar electrokinetic chromatography method was established for the quantitative analysis of seven podophyllum lignans in Podophyllum emodi Wall. var. chinesis sprague. The optimum buffer system was 10 mM NaH2PO4–5 mM borate–100 mM sodium dodecylsulfate–30% isopropanol (pH 7.20). Voltage was 18 kV and detection at 214 nm. The second derivative chromatogram was used to determine a low-content component and those

Shuhui Liu; Xuan Tian; Xingguo Chen; Zhide Hu



Electrokinetic pumping of liquid propellants for small satellite microthruster applications  

Microsoft Academic Search

For most orbital maneuvers, small satellites weighing less than 10kg require propulsion systems capable of producing thrust in the micro-Newton to milli-Newton force range. At this scale, electrokinetic (EK) pumping offers a method to precisely meter liquid propellants under purely electrical control at pressures and flow rates well-suited for microthruster applications. After exploring a variety of materials and surface treatments

Kamlesh D. Patel; Michael S. Bartsch; Matthew H. McCrink; Jennifer S. Olsen; Bruce P. Mosier; Robert W. Crocker



Electrokinetically Pumped Liquid Propellant Microthrusters for Orbital Station Keeping  

Microsoft Academic Search

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

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



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


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

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



Optimization of an electrokinetic mixer for microfluidic applications  

PubMed Central

This work is concerned with the investigation of the concentration fields in an electrokinetic micromixer and its optimization in order to achieve high mixing rates. The mixing concept is based on the combination of an alternating electrical excitation applied to a pressure-driven base flow in a meandering microchannel geometry. The electrical excitation induces a secondary electrokinetic velocity component, which results in a complex flow field within the meander bends. A mathematical model describing the physicochemical phenomena present within the micromixer is implemented in an in-house finite-element-method code. We first perform simulations comparable to experiments concerned with the investigation of the flow field in the bends. The comparison of the complex flow topology found in simulation and experiment reveals excellent agreement. Hence, the validated model and numerical schemes are employed for a numerical optimization of the micromixer performance. In detail, we optimize the secondary electrokinetic flow by finding the best electrical excitation parameters, i.e., frequency and amplitude, for a given waveform. Two optimized electrical excitations featuring a discrete and a continuous waveform are discussed with respect to characteristic time scales of our mixing problem. The results demonstrate that the micromixer is able to achieve high mixing degrees very rapidly. PMID:22712034

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



Principles of Micellar Electrokinetic Capillary Chromatography Applied in Pharmaceutical Analysis  

PubMed Central

Since its introduction capillary electrophoresis has shown great potential in areas where electrophoretic techniques have rarely been used before, including here the analysis of pharmaceutical substances. The large majority of pharmaceutical substances are neutral from electrophoretic point of view, consequently separations by the classic capillary zone electrophoresis; where separation is based on the differences between the own electrophoretic mobilities of the analytes; are hard to achieve. Micellar electrokinetic capillary chromatography, a hybrid method that combines chromatographic and electrophoretic separation principles, extends the applicability of capillary electrophoretic methods to neutral analytes. In micellar electrokinetic capillary chromatography, surfactants are added to the buffer solution in concentration above their critical micellar concentrations, consequently micelles are formed; micelles that undergo electrophoretic migration like any other charged particle. The separation is based on the differential partitioning of an analyte between the two-phase system: the mobile aqueous phase and micellar pseudostationary phase. The present paper aims to summarize the basic aspects regarding separation principles and practical applications of micellar electrokinetic capillary chromatography, with particular attention to those relevant in pharmaceutical analysis. PMID:24312804

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



Analysis of flavonoids by capillary zone electrophoresis with electrokinetic supercharging.  


On-line concentration via Electrokinetic Supercharging (EKS) was used to enhance the sensitivity of the capillary electrophoretic separation of the four flavonoids naringenin, hesperetin, naringin and hesperidin. Separation conditions, including the background electrolyte pH and concentration, the length and choice of terminator and the electrokinetic injection time were optimized. The optimum conditions were: a background electrolyte of 30 mM sodium tetraborate (pH 9.5) containing 5% (v/v) of methanol, electrokinetic injection of the sample (130 s, -10 kV) followed by hydrodynamic injecting of 100 mM 2-(cyclohexylamino)ethanesulfonic acid (CHES) (17 s, 0.5 psi) as terminator, and separation with -20 kV. Under these conditions the four flavonoids could be separated with a sample-to-sample time of 15 min and detection limits from 2.0 to 6.8 ng mL(-1). When compared to a conventional hydrodynamic injection the sensitivity was enhanced between 824 and 1515 times which is 7.6-16 times higher than other CE methods for the on-line concentration of flavonoids. The applicability of the developed method was demonstrated by the detection of the four flavonoids in an aqueous extract of Clematis hexapetala pall. PMID:21949941

Zhong, Hao; Yao, Qingqiang; Breadmore, Michael C; Li, Yumei; Lu, Yuanqi



Cytotoxic Effect of Paclitaxel Incorporated in Nanoparticles Based on Lactic and Glycolic Acid Copolymer  

Microsoft Academic Search

Paclitaxel dosage form on nanoparticles of 200–300 nm based on lactic and glycolic acid copolymer was obtained by the co-precipitation\\u000a method. The possibility of controlled release of paclitaxel at pH 7.4 for 24 h was studied in vitro. Studies on Jurkat\\/WT human T-lymphoblastic leukemia cells showed that incorporation of paclitaxel in the nanoparticles led\\u000a to a 4-fold increase of its cytotoxicity (6.8?×?10?6 M)

V. Bojat; D. S. Baranov; E. A. Oganesyan; Y. M. Hamdy; V. Yu. Balaban’yan; R. N. Alyautdin



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

USGS Publications Warehouse

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

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



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

USGS Publications Warehouse

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

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



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

NASA Technical Reports Server (NTRS)

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

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



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


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

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



A Liposomal Formulation Able to Incorporate a High Content of Paclitaxel and Exert Promising Anticancer Effect  

PubMed Central

A liposome formulation for paclitaxel was developed in this study. The liposomes, composed of naturally unsaturated and hydrogenated phosphatidylcholines, with significant phase transition temperature difference, were prepared and characterized. The liposomes exhibited a high content of paclitaxel, which was incorporated within the segregated microdomains coexisting on phospholipid bilayer of liposomes. As much as 15% paclitaxel to phospholipid molar ratio were attained without precipitates observed during preparation. In addition, the liposomes remained stable in liquid form at 4°C for at least 6 months. The special composition of liposomal membrane which could reduce paclitaxel aggregation could account for such a capacity and stability. The cytotoxicity of prepared paclitaxel liposomes on the colon cancer C-26 cell culture was comparable to Taxol. Acute toxicity test revealed that LD50 for intravenous bolus injection in mice exceeded by 40?mg/kg. In antitumor efficacy study, the prepared liposomal paclitaxel demonstrated the increase in the efficacy against human cancer in animal model. Taken together, the novel formulated liposomes can incorporate high content of paclitaxel, remaining stable for long-term storage. These animal data also demonstrate that the liposomal paclitaxel is promising for further clinical use. PMID:21490755

Kan, Pei; Tsao, Chih-Wan; Wang, Ae-June; Su, Wu-Chou; Liang, Hsiang-Fa



Electrokinetic-flow-induced viscous drag on a tethered DNA inside a nanopore  

E-print Network

Recent work has shown that the resistive force arising from viscous effects within the pore region could explain [Ghosal, S. Phys. Rev. E. vol. 71, 051904 (2006) and Phys. Rev. Lett. vol. 98, 238104 (2007)] observed translocation times in certain experiments involving voltage driven translocations of DNA through nanopores. The electrokinetic flow inside the pore and the accompanying viscous effects also play a crucial role in the interpretation of experiments where the DNA is immobilized inside a nanopore[U. Keyser, et al., Nature Physics vol. 2, 473 (2006)]. In this paper the viscous force is explicitly calculated for a nanopore of cylindrical geometry. It is found that the reduction of the tether force due to viscous drag and due to charge reduction by Manning condensation are of similar size. The result is of importance in the interpretation of experimental data on tethered DNA.

Sandip Ghosal



Electrokinetic-flow-induced viscous drag on a tethered DNA inside a nanopore  

E-print Network

Recent work has shown that the resistive force arising from viscous effects within the pore region could explain [Ghosal, S. Phys. Rev. E. vol. 71, 051904 (2006) and Phys. Rev. Lett. vol. 98, 238104 (2007)] observed translocation times in certain experiments involving voltage driven translocations of DNA through nanopores. The electrokinetic flow inside the pore and the accompanying viscous effects also play a crucial role in the interpretation of experiments where the DNA is immobilized inside a nanopore[U. Keyser, et al., Nature Physics vol. 2, 473 (2006)]. In this paper the viscous force is explicitly calculated for a nanopore of cylindrical geometry. It is found that the reduction of the tether force due to viscous drag and due to charge reduction by Manning condensation are of similar size. The result is of importance in the interpretation of experimental data on tethered DNA.

Ghosal, Sandip



High electrokinetic energy conversion efficiency in charged nanoporous nitrocellulose/sulfonated polystyrene membranes.  


The synthesis, characterization, and electrokinetic energy conversion performance have been investigated experimentally in a charged polymeric membrane based on a blend of nitrocellulose and sulfonated polystyrene. The membrane is characterized by a moderate ion exchange capacity and a relatively porous structure with average pore diameter of 11 nm. With electrokinetic energy conversion, pressure can be converted directly into electric energy and vice versa. From the electrokinetic transport properties, a remarkably large intrinsic maximum efficiency of 46% is found. It is anticipated that the results are an experimental verification of theoretical models that predict high electrokinetic energy conversion efficiency in pores with high permselectivity and hydrodynamic slip flow. Furthermore, the result is a promising step for obtaining efficient low-cost electrokinetic generators and pumps for small or microscale applications. PMID:25555128

Haldrup, Sofie; Catalano, Jacopo; Hansen, Michael Ryan; Wagner, Manfred; Jensen, Grethe Vestergaard; Pedersen, Jan Skov; Bentien, Anders



High figure of merit for electrokinetic energy conversion in Nafion membranes  

NASA Astrophysics Data System (ADS)

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

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



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


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

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



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

SciTech Connect

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.

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



Design of lipid matrix particles for fenofibrate: effect of polymorphism of glycerol monostearate on drug incorporation and release.  


The effect of polymorphism of glycerol monostearate (GMS) on drug incorporation and release from lipid matrix particles (LMPs) was investigated using fenofibrate as a model drug. X-ray powder diffraction and differential scanning calorimetry were used to study the polymorphism change of GMS and the drug incorporation in GMS matrix. When medium-chain triglycerides (MCT) was absent, melted GMS was frozen to ?-form of GMS with drug molecularly dispersed, whereas ?-form of GMS was formed with part of drug crystallized out when the ratio of GMS/MCT in the lipid matrix was 2:1 (w/w). For LMP composed of GMS/MCT (2:1, w/w) prepared, GMS was in ?-form when the particles were in nanometer range, whereas GMS was in ?-form when lipid particles were in micrometer range. The model drug was molecularly dispread in ?-form lipid nanoparticles, whereas part of drug was expulsed out from microparticles because of the denser crystalline packing than ?-form of GMS, and caused a faster drug release from lipid microparticles than that from nanoparticles. During the storage, the transformation of GMS from ?-form into the more stable ?-form promoted drug expulsion and caused drug precipitation. In conclusion, the polymorphism of GMS is an important factor determining particle stability, drug incorporation, and the release of the drug from LMP. Critical attention should be paid on the investigation as well as control of the lipid polymorphism when formulating lipid-based matrix particles. PMID:24375427

Xia, Dengning; Cui, Fude; Gan, Yong; Mu, Huiling; Yang, Mingshi



Removal of Pb from a calcareous soil during EDTA-enhanced electrokinetic extraction.  


Electrokinetic extraction has been tested to remove lead from an Algerian contaminated soil ([Pb] = 4.432 +/- 0.275 mg g(-1)) sited near a battery plant. The effect of EDTA at various concentrations (0.05-0.20 M) on the enhancement of lead transport has been studied by applying a constant voltage corresponding to a nominal electric field strength of 1 V cm(-1) (duration: 240 h). Results of contaminant distribution across the experimental cell have shown efficient transport of lead toward the anode despite the presence of calcite (25%) and the high acid/base buffer capacity of the soil. To avoid ligand loss, which would be anodically oxidized, the cell was modified by adding extra compartments and inserting cation exchange membranes (Neosepta CMX). Thus, simultaneous recovery of EDTA and lead from their chelated solutions has been made possible using the same set-up and by controlling fluids chemistry. PMID:16198669

Amrate, S; Akretche, D E; Innocent, C; Seta, P



Electrokinetic remediation and microbial community shift of ?-cyclodextrin-dissolved petroleum hydrocarbon-contaminated soil.  


Electrokinetic (EK) migration of ?-cyclodextrin (?-CD), which is inclusive of total petroleum hydrocarbon (TPH), is an economically beneficial and environmentally friendly remediation process for oil-contaminated soils. Remediation studies of oil-contaminated soils generally prepared samples using particular TPHs. This study investigates the removal of TPHs from, and electromigration of microbial cells in field samples via EK remediation. Both TPH content and soil respiration declined after the EK remediation process. The strains in the original soil sample included Bacillus sp., Sporosarcina sp., Beta proteobacterium, Streptomyces sp., Pontibacter sp., Azorhizobium sp., Taxeobacter sp., and Williamsia sp. Electromigration of microbial cells reduced the biodiversity of the microbial community in soil following EK remediation. At 200 V?m(-1) for 10 days, 36% TPH was removed, with a small population of microbial cells flushed out, demonstrating that EK remediation is effective for the present oil-contaminated soils collected in field. PMID:21052991

Wan, Chunli; Du, Maoan; Lee, Duu-Jong; Yang, Xue; Ma, Wencheng; Zheng, Lina



Electrokinetic and surface chemical characterizations of an irradiated microfiltration polysulfone membrane: comparison of two irradiation doses.  


The effect of ionizing radiation on the surface and electrokinetic characteristic parameters for a porous membrane of pore size 0.2 mum is determined and correlated with the irradiation dose (10 and 80 J/kg). Changes in NaCl permeability and membrane system electrical resistance determined from diffusion and impedance spectroscopy measurements are consistent with the increase of membrane pore radii/porosity, in agreement with SEM micrographs and reported results. Low irradiation dose seems to clean the membrane surface of impurities, according to XPS results, but the increase of irradiation doses could affect surface roughness. Due to the relatively high pore radius, ion transport numbers are practically independent of radiation and dose, but irradiation slightly modifies the membrane solution interface by increasing its weakly electronegative character, which could be of interest in the ultrafiltration of proteins or macromolecules. PMID:17349653

de Lara, R; Benavente, J



Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils  


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

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



Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils  


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

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



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

SciTech Connect

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

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



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

NASA Astrophysics Data System (ADS)

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.

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



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

PubMed Central

The effect of trimethoprim [2,4-diamino-5(2?,4?,5?trimethoxybenzyl)-pyrimidine] in the presence of thymine on Escherichia coli B temperature-sensitive and non-temperature-sensitive Thy? strains and a phosphodeoxyribomutase-negative mutant was studied. The inhibitory effect of 5 ?g of trimethoprim per ml on the growth of E. coli B was not overcome by thymine, thymidine, or thymidylate even in the presence of one-carbon metabolites and related metabolites. Deoxyribonucleic acid (DNA) and protein synthesis were more severely inhibited than ribonucleic acid (RNA) synthesis. The inhibition of DNA synthesis was partially reversed by addition of deoxyadenosine to increase the incorporation of exogenous thymine. By contrast, the inhibition of protein was not reversed even with one-carbon metabolites present, in keeping with the requirement for formylmethionyl-transfer RNAF for initiation. However, the inhibition of both DNA and protein synthesis in a phosphodeoxyribomutase-negative strain by 1 ?g of trimethoprim per ml with thymine present was partially reversed by deoxyadenosine and one-carbon metabolites, and nearly normal growth occurred. 5-Fluorodeoxyuridine added at the time of addition of trimethoprim prevented the inhibition. Sulfadiazine in the presence of thymine inhibited both Thy+ and Thy? strains whereas trimethoprim (with thymine) did not inhibit Thy? organisms. The effect of trimethoprim on the incorporation of labeled thymine into DNA was also studied. These experiments support the concept that trimethoprim in conjunction with the action of thymidylate synthetase inhibits the growth of Thy+ cells because of a depletion of tetrahydrofolate. DNA synthesis is inhibited initially by a limitation of thymine nucleotide precursor, resulting from the indirect inhibition of thymidylate synthetase and the poor incorporation of exogenous thymine. PMID:4260561

Dale, Beverly A.; Greenberg, G. Robert



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

SciTech Connect

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

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



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

NASA Astrophysics Data System (ADS)

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

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



Single-layer triplet white polymer light-emitting diodes incorporating polymer oxides: Effect of charge trapping at phosphorescent dopants  

NASA Astrophysics Data System (ADS)

This paper describes the effects of charge trapping on the device performances of triplet polymer light-emitting diodes (PLEDs) after the cathode contact had been improved through the blending of poly(ethylene glycol) (PEG) into the active layer. The external quantum efficiency (EQE) was enhanced when the dopant tended to trap electrons. In contrast, we observed no EQE enhancement for the device featuring a hole-trapping dopant. Because PEG promoted electron injection, more electrons were trapped in the triplet molecules, thereby enhancing the probability of recombination. Finally, after incorporating PEG, we further achieved white PLEDs exhibiting both high EQE and high power efficiency.

Chen, Fang-Chung; Chien, Shang-Chieh; Chen, Yung-Shiuan



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

SciTech Connect

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

Zheng, Haisheng; Ramalingam, Balavinayagam; Korampally, Venumadhav; Gangopadhyay, Shubhra, E-mail: [Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65201 (United States)] [Department of Electrical and Computer Engineering, University of Missouri, Columbia, Missouri 65201 (United States)



Effect of specific energy consumption on fineness of portland cement incorporating amine or glycol-based grinding aids  

Microsoft Academic Search

A comprehensive research project was undertaken to evaluate the effect of specific energy consumption (Ec) on variations of\\u000a portland cement fineness measured by the Blaine test and sieve analysis. Amine and glycol-based grinding aids (GA) were incorporated\\u000a at various concentrations of 0.04, 0.06, and 0.08% of the cement weight. At Ec values lower than around 20 kWh\\/ton, test results\\u000a have shown

Joseph J. Assaad; Salim E. Asseily; Jacques Harb



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


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

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



Separation and on-line preconcentration by stacking and sweeping of charged analytes in the plant by microemulsion electrokinetic chromatography with nonionic surfactants  

Microsoft Academic Search

A novel on-line technique for stacking and sweeping of long sample plugs with simultaneous determination of charged analytes in the plant (protocatechuic aldehyde, rosmarinic acid, danshensu, salvianolic acid B, and protocatechuic acid) by the nonionic microemulsion electrokinetic chromatography (MEEKC) is presented. The preconcentration efficiency provided about 9–28-fold for stacking and 7–14-fold for sweeping in the enhancements of LOD. The effects

Jun Cao; Lian-Wen Qi; E-Hu Liu; Wei-dong Zhang; Ping Li



Effect of silver nanoparticles incorporated with samarium-doped magnesium tellurite glasses  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (Ag NPs) are incorporated in samarium doped tellurite glass of a composition (89-x)TeO2-10MgO-1Sm2O3-xAgCl, where 0.0?x?0.6 mol%, by a melt quenching technique. It is found that all the glasses are amorphous in nature, and the existence of Ag NPs with an average size of 16.94 nm is confirmed by Transmission Electron Microscopy. Meanwhile, their physical properties such as glass density, molar volume and ionic packing density are computed utilizing the normal method. The density and ionic packing density are observed to decrease with increasing Ag NPs, but increase when the Ag NPs are beyond 0.2 mol%. On the other hand, the molar volume behaves exactly opposite to the increase in Ag NPs content. It decreases when the Ag NPs content value is more than 0.2 mol%. The optical energy band gap and Urbach energy are evaluated from the absorption spectra in the range of 200-900 nm at room temperature. It is also observed that the direct and indirect optical energy band gaps reduce with Ag NPs content, but enhance when the Ag NPs are beyond 0.2 mol%. Meanwhile, the Urbach energy is found to increase as the Ag NPs content is increased but decreases when Ag NPs is 0.2 mol%. The refractive index is deduced from indirect optical energy band gap. Meanwhile, molar refraction and electronic polarizability have been calculated from the Lorentz-Lorentz relation. Refractive index and electronic polarizability are also observed to raise with Ag NPs content, but drop off when Ag NPs content is more than 0.2 mol%. In this paper, all properties are discussed with respect to the Ag NPs concentration.

Yusoff, N. M.; Sahar, M. R.



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

SciTech Connect

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

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




EPA Science Inventory

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


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


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

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



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


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

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



Separation of diastereoisomers of podophyllum lignans by micellar electrokinetic chromatography  

Microsoft Academic Search

Seven pairs of diastereoisomers of podophyllum lignans at 2-position, including two pairs of spin-labeled compounds, were separated by micellar electrokinetic chromatography with 5 mM sodium tetraborate–20 mM NaH2PO4–120 mM sodium dodecylsulfate–30% (v\\/v) 2-propanol (pH 6.5–7) within 35 min. The migration behaviors of the compounds with different types and concentrations of organic modifiers were studied. The method can be used to

Shuhui Liu; Xuan Tian; Xingguo Chen; Zhide Hu



Electrokinetic instability near charge-selective hydrophobic surfaces.  


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. PMID:25122363

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



Electrokinetic instability near charge-selective hydrophobic surfaces  

NASA Astrophysics Data System (ADS)

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.

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




SciTech Connect

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.

E. James Davis



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

E-print Network

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...

Burckhardt, Heather Ann




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 ...


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

PubMed Central

Clinical data indicate that secondary caries and restoration fracture are the most common problems facing tooth restorations. Our ultimate goal was to develop mechanically-strong and caries-inhibiting dental composites. The specific goal of this pilot study was to understand the relationships between composite properties and the ratio of reinforcement filler/releasing filler. Nanoparticles of monocalcium phosphate monohydrate (MCPM) were synthesized and incorporated into a dental resin for the first time. Silicon carbide whiskers were fused with silica nanoparticles and mixed with the MCPM particles at MCPM/whisker mass ratios of 1:0, 2:1, 1:1, 1:2, and 0:1. The composites were immersed for 1–56 days to measure Ca and PO4 release. When the MCPM/whisker ratio was changed from 0:1 to 1:2, the composite flexural strength (mean ± SD; n = 5) decreased from 174 ± 26 MPa to 138 ± 9 MPa (p < 0.05). A commercial nonreleasing composite had a strength of 112 ± 14 MPa. When the MCPM/whisker ratio was changed from 1:2 to 1:1, the Ca concentration at 56 days increased from 0.77 ± 0.04 mmol/L to 1.74 ± 0.06 mmol/L (p < 0.05). The corresponding PO4 concentration increased from 3.88 ± 0.21 mmol/L to 9.95 ± 0.69 mmol/L (p < 0.05). Relationships were established between the amount of release and the MCPM volume fraction vMCPM in the resin: [Ca]= 42.9 vMCPM2.7, and [PO4] = 48.7 vMCPM1.4. In summary, the method of combining nanosized releasing fillers with reinforcing fillers yielded Ca- and PO4-releasing composites with mechanical properties matching or exceeding a commercial stress-bearing, nonreleasing composite. This method may be applicable to the use of other Ca–PO4 fillers in developing composites with high stress-bearing and caries-preventing capabilities, a combination not yet available in any dental materials. PMID:16924611

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



Effects of high frequency ultrasound irradiation on incorporation of SiO2 particles within polypyrrole films.  


This paper deals with the effect of ultrasound on polypyrrole/SiO2 composite film elaboration through various steps (particle dispersion, electrosynthesis). Experiments were carried out on stainless steel in phosphoric acid solution. An efficient method for dispersion of SiO2 particles prior to electropolymerization, based on low frequency irradiation (20kHz), was proposed. It was shown that mechanical effects of high frequency ultrasound (i.e. mass transfer improvement) led to enhancement of electropolymerization kinetics. Scanning electron microscopy imaging and glow discharge optical emission spectroscopy revealed localization of SiO2 particles in the outer region of the films as well as better incorporation of particles under high frequency ultrasound irradiation. Finally, anticorrosion behavior of formed films was investigated in sodium chloride solution by Open Circuit Potential and anodic polarization methods. The results showed that polypyrrole/SiO2 films elaborated under ultrasound irradiation exhibit the best protective performances. PMID:24835022

Grari, O; Dhouibi, L; Lallemand, F; Buron, C C; Et Taouil, A; Hihn, J Y



Effect of Control-released Basic Fibroblast Growth Factor Incorporated in ?-Tricalcium Phosphate for Murine Cranial Model  

PubMed Central

Background: ?-Tricalcium phosphate (?-TCP) is used clinically as a bone substitute, but complete osteoinduction is slow. Basic fibroblast growth factor (bFGF) is important in bone regeneration, but the biological effects are very limited because of the short half-life of the free form. Incorporation in gelatin allows slow release of growth factors during degradation. The present study evaluated whether control-released bFGF incorporated in ?-TCP can promote bone regeneration in a murine cranial defect model. Methods: Bilateral cranial defects of 4?mm in diameter were made in 10-week-old male Sprague-Dawley rats treated as follows: group 1, 20 ?l saline as control; group 2, ?-TCP disk in 20 ?l saline; group 3, ?-TCP disk in 50 ?g bFGF solution; and group 4, ?-TCP disk in 50 ?g bFGF-containing gelatin hydrogel (n = 6 each). Histological and imaging analyses were performed at 1, 2, and 4 weeks after surgery. Results: The computed tomography value was lower in groups 3 and 4, whereas the rate of osteogenesis was higher histologically in group 4 than in the other groups. The appearance of tartrate-resistant acid phosphate–positive cells and osteocalcin-positive cells and disappearance of osteopontin-positive cells occurred earlier in group 4 than in the other groups. Conclusions: These findings suggest that control-released bFGF incorporated in ?-TCP can accelerate bone regeneration in the murine cranial defect model and may be promising for the clinical treatment of cranial defects. PMID:25289319

Shimizu, Azusa; Tajima, Satoshi; Tobita, Morikuni; Tanaka, Rica; Tabata, Yasuhiko



Extinction-effective population index: incorporating life-history variations in population viability analysis.  


Viability status of populations is a commonly used measure for decision-making in the management of populations. One of the challenges faced by managers is the need to consistently allocate management effort among populations. This allocation should in part be based on comparison of extinction risks among populations. Unfortunately, common criteria that use minimum viable population size or count-based population viability analysis (PVA) often do not provide results that are comparable among populations, primarily because they lack consistency in determining population size measures and threshold levels of population size (e.g., minimum viable population size and quasi-extinction threshold). Here I introduce a new index called the "extinction-effective population index," which accounts for differential effects of demographic stochasticity among organisms with different life-history strategies and among individuals in different life stages. This index is expected to become a new way of determining minimum viable population size criteria and also complement the count-based PVA. The index accounts for the difference in life-history strategies of organisms, which are modeled using matrix population models. The extinction-effective population index, sensitivity, and elasticity are demonstrated in three species of Pacific salmonids. The interpretation of the index is also provided by comparing them with existing demographic indices. Finally, a measure of life-history-specific effect of demographic stochasticity is derived. PMID:17918411

Fujiwara, Masami



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

ERIC Educational Resources Information Center

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

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



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

ERIC Educational Resources Information Center

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

Hilbelink, Amy J.



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

E-print Network

, Auto-Searched Orographic and Atmospheric Effects Detrended Kriging (ASOADeK), is introduced to map. The spatially detrended gauge data are further interpolated by ordinary kriging to generate a residual precipitation surface. The precipitation map is then constructed by adding the regression surface to the kriged

Texas at San Antonio, University of


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


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

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



An improved analytical model of 4H-SiC MESFET incorporating bulk and interface trapping effects  

NASA Astrophysics Data System (ADS)

An improved analytical model for the current—voltage (I–V) characteristics of the 4H-SiC metal semiconductor field effect transistor (MESFET) on a high purity semi-insulating (HPSI) substrate with trapping and thermal effects is presented. The 4H-SiC MESFET structure includes a stack of HPSI substrates and a uniformly doped channel layer. The trapping effects include both the effect of multiple deep-level traps in the substrate and surface traps between the gate to source/drain. The self-heating effects are also incorporated to obtain the accurate and realistic nature of the analytical model. The importance of the proposed model is emphasised through the inclusion of the recent and exact nature of the traps in the 4H-SiC HPSI substrate responsible for substrate compensation. The analytical model is used to exhibit DC I–V characteristics of the device with and without trapping and thermal effects. From the results, the current degradation is observed due to the surface and substrate trapping effects and the negative conductance introduced by the self-heating effect at a high drain voltage. The calculated results are compared with reported experimental and two-dimensional simulations (Silvaco®-TCAD). The proposed model also illustrates the effectiveness of the gate—source distance scaling effect compared to the gate—drain scaling effect in optimizing 4H-SiC MESFET performance. Results demonstrate that the proposed I–V model of 4H-SiC MESFET is suitable for realizing SiC based monolithic circuits (MMICs) on HPSI substrates.

Hema Lata Rao, M.; Narasimha Murty, N. V. L.



Effect of sodium incorporation into CuInSe2 from first principles  

NASA Astrophysics Data System (ADS)

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

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



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

Microsoft Academic Search

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

Werner Brack; Robert M. Burgess


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

Microsoft Academic Search

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

P. Watson; T. H. Topper



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


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

Cooley, Brian C; Herrera, Anthony J



Electrokinetics Enhanced Delivery of Nano-scale Zero Valent Iron  

NASA Astrophysics Data System (ADS)

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

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



Electrokinetic shape changes of cochlear outer hair cells.  


Rapid mechanical changes have been associated with electrical activity in a variety of non-muscle excitable cells. Recently, mechanical changes have been reported in cochlear hair cells. Here we describe electrically evoked mechanical changes in isolated cochlear outer hair cells (OHCs) with characteristics which suggest that direct electrokinetic phenomena are implicated in the response. OHCs make up one of two mechanosensitive hair cell populations in the mammalian cochlea; their role may be to modulate the micromechanical properties of the hearing organ through mechanical feedback mechanisms. In the experiments described here, we applied sinusoidally modulated electrical potentials across isolated OHCs; this produced oscillatory elongation and shortening of the cells and oscillatory displacements of intracellular organelles. The movements were a function of the direction and strength of the electrical field, were inversely related to the ionic concentration of the medium, and occurred in the presence of metabolic uncouplers. The cylindrical shape of the OHCs and the presence of a system of membranes within the cytoplasm--laminated cisternae--may provide the anatomical substrate for electrokinetic phenomena such as electro-osmosis. PMID:3736662

Kachar, B; Brownell, W E; Altschuler, R; Fex, J


Feasibility of electrokinetic oxygen supply for soil bioremediation purposes.  


This paper studies the possibility of providing oxygen to a soil by an electrokinetic technique, so that the method could be used in future aerobic polluted soil bioremediation treatments. The oxygen was generated from the anodic reaction of water electrolysis and transported to the soil in a laboratory-scale electrokinetic cell. Two variables were tested: the soil texture and the voltage gradient. The technique was tested in two artificial soils (clay and sand) and later in a real silty soil, and three voltage gradients were used: 0.0 (control), 0.5, and 1.0Vcm(-1). It was observed that these two variables strongly influenced the results. Oxygen transport into the soil was only available in the silty and sandy soils by oxygen diffusion, obtaining high dissolved oxygen concentrations, between 4 and 9mgL(-1), useful for possible aerobic biodegradation processes, while transport was not possible in fine-grained soils such as clay. Electro-osmotic flow did not contribute to the transport of oxygen, and an increase in voltage gradients produced higher oxygen transfer rates. However, only a minimum fraction of the electrolytically generated oxygen was efficiently used, and the maximum oxygen transport rate observed, approximately 1.4mgO2L(-1)d(-1), was rather low, so this technique could be only tested in slow in-situ biostimulation processes for organics removal from polluted soils. PMID:25173714

Mena Ramírez, E; Villaseñor Camacho, J; Rodrigo Rodrigo, M A; Cañizares Cañizares, P



Electrokinetic particle separation in a single-spiral microchannel  

NASA Astrophysics Data System (ADS)

The efficient separation of discrete particle species is a topic of interest in numerous research fields for its practical application to problems encountered in both academia and industry. We have recently developed an electrokinetic technique that exploits the curvature-induced dielectrophoresis (C-iDEP) to continuously sort particles by inherent properties in asymmetric double-spiral microchannels. Herein we demonstrate that a single-spiral microchannel is also sufficient for a continuous-flow sheathless electrokinetic particle separation. This method relies on C-iDEP to focus particles to a tight stream and the wall-induced electric lift to manipulate the aligned particles to size-dependent equilibrium positions, both of which happen simultaneously inside the spiral. A theoretical model is developed to understand this size-based separation, which has been implemented for both a binary mixture and a ternary mixture of colloidal particles. The obtained analytical formulae predict with a close agreement both the experimentally measured particle center–wall distance and the necessary electric field for a complete particle focusing in the spiral.

DuBose, John; Zhu, Junjie; Patel, Saurin; Lu, Xinyu; Tupper, Nathaniel; Stonaker, John M.; Xuan, Xiangchun



Research on the Heavy Metal Recovery using the Electrokinetic Phenomenon  

NASA Astrophysics Data System (ADS)

Recently, the pollution of the soil by heavy metal elution from industrial effluents and so on becomes serious with the development of the industry. Until now, many techniques such as diffusion prevention and elution prevention, extraction and removal, decomposition and decontamination have been proposed in the method of processing of polluted soil. In recent years, especially the method for using the electrokinetic phenomenon is noticed. In this method, the paired electrode is inserted in the soil, and the DC voltage is applied. Then, the electrokinetic phenomenon by the procedure of the superscription, namely electrophoresis, electroendosmose, electrolysis, is utilized. However, in the conventional research, recovery quantity of the heavy metal ion is low, and the improvement in the recovery efficiency is desired in order to use this technique for the repair of the polluted soil. Following fact is mentioned as the reason why the recovery efficiency of the heavy metal ion lowers. When the heavy metal ion has moved from the anode to the cathode, it combines with hydroxide ion made by the electrolysis of the water at the cathode, and it has precipitated as a hydroxide. The purpose of this study is prevention of the alkalinization by adding the acid at the proper quantity, and improves the recovery efficiency of the heavy metal ion.

Suzuki, Masafumi; Shoji, Tomoyoshi; Yoshimura, Noboru


Concentration polarization of interface and non-linear electrokinetic phenomena.  


The review addresses the peculiarities of concentration polarization caused by an electric current passing through conducting and around nonconducting charged materials. The conditions of emergence of an induced space charge of large density and thickness behind an electrical double layer, leading to strong non-linearity of electroosmosis and electrophoresis, are analyzed. Basic findings about concentration polarization, its theoretical modeling and experimental investigations, as well as its influence on electrokinetic phenomena and mass transfer through ion-exchange materials are discussed from the point of view of the fundamental knowledge about polarization processes and from the perspective of their practical application. The analysis focuses on the main properties of concentration polarization, electroosmotic flow of liquid around single fixed particles and through the system of particles, and electrophoresis of particles suspended in aqueous medium and current through flat, spherical and cylindrical interfaces and membranes with heterogeneous conductivity. The paper also presents the general ideas of concentration polarization and non-linear electrokinetic phenomena in case of nonconducting particles and their dependence on particle surface electroconductivity. Existing theoretical models describing polarization of nonconducting particles at high and low Peclet numbers are analyzed, with appropriate experimental data being provided to validate the theory. A joint analysis of polarization of conducting and nonconducting particles completes the review. PMID:20810097

Mishchuk, Nataliya A



Effect of incorporating rape seed oil on quality of ice cream  

Microsoft Academic Search

A study was carried out to determine the effects of use of rape seed oil in the production of ice cream. The basic ice cream,\\u000a i.e., control (C) had 4.5% milk fat, 11.75% MSNF, 1.25% whey protein concentrate-70 (WPC-70), 15% sucrose, 0.2% sodium alginate,\\u000a and 0.2% glycerol monostearate with a total solids content of 32.9%, vanilla flavored ice cream was

M. Nadeem; M. Abdullah; M. Y. Ellahi



VBEFP: a valence bond approach that incorporates effective fragment potential method.  


An ab initio explicit solvation valence bond (VB) method, called VBEFP, is presented. The VBEFP method is one type of QM/MM approach in which the QM part of system is treated within the ab initio valence bond scheme and the solvent water molecules are accounted by the effective fragment potential (EFP) method, which is a polarized force field approach developed by Gordon et al. (J. Chem. Phys. 1996, 105, 1968). This hybrid method enables one to take the first-solvation shell and heterogeneous solvation effects into account explicitly with VB wave function. Therefore, the nature of chemical bonding and the mechanism of chemical reactions with explicit solvent environments can be explored at the ab inito VB level. In this paper, the hydrated metal-ligand complexes [M(2+)L](H(2)O)(n) (M(2+): Mg(2+), Zn(2+); L: NH(3), CH(2)O) are studied by the VBEFP method. Resonance energy and bond order are computed, and the influence of the solvent coordination and hydrogen bonding to the metal-ligand bonding are explored in the paper. PMID:22276645

Ying, Fuming; Chang, Xin; Su, Peifeng; Wu, Wei



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

NASA Astrophysics Data System (ADS)

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.

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



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

PubMed Central

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

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



Annealing effect of platinum-incorporated nanowires created by focused ion/electron-beam-induced deposition  

NASA Astrophysics Data System (ADS)

Focused ion-beam-induced deposition (FIBID) and focused electron-beam-induced deposition (FEBID) are convenient and useful in nanodevice fabrication. Since the deposition is from the organometallic platinum precursor, the conductive lines directly written by focused ion-beam (FIB) and focused electron-beam (FEB) are carbon-rich materials. We discuss an alternative approach to enhancing the platinum content and improving the conductivity of the conductive leads produced by FIBID and FEBID, namely an annealing treatment. Annealing in pure oxygen at 500 °C for 30 min enhances the platinum content values from ~18% to 30% and ~ 50% to 90% of FIBID and FEBID, respectively. Moreover, we find that thin films will be formed in the FIBID and FEBID processes. The annealing treatment is helpful to avoid the current leakage caused by these thin films. A single electron transistor is fabricated by FEBID and the current—voltage curve shows the Coulomb blockade effect.

Fang, Jing-Yue; Qin, Shi-Qiao; Zhang, Xue-Ao; Liu, Dong-Qing; Chang, Sheng-Li



Sensitive enantioanalysis of ?-blockers via field-amplified sample injection combined with water removal in microemulsion electrokinetic chromatography.  


In this study, an on-line sample preconcentration technique, field-amplified sample injection combined with water removal by electroosmotic flow (EOF) pump, was applied to realize a highly sensitive chiral analysis of ?-blocker enantiomers by MEEKC. The introduction of a water plug in capillary before the electrokinetic injection provided the effective preconcentration of chiral compounds. And then the water was moving out of the column from the injection end under the effect of the EOF, which avoided dilution of the stacked ?-blocker enantiomers concentration suffering from the presence of water in separation buffer. Moreover, the addition of H3 PO4 and methanol in the sample solution greatly improved the enhancement efficiency further. Under optimized conditions, more than 2700-fold enhancement in sensitivity was obtained for each enantiomer of bupranolol (BU), alprenolol (AL), and propranolol (PRO) via electrokinetic injection. LODs were 0.10, 0.10, 0.12, 0.11, 0.02, and 0.02 ng/mL for S-BU, R-BU, S-AL, R-AL, S-PRO, and R-PRO, respectively. Eventually, the proposed method was successfully applied to the determination of BU, AL, and PRO in serum samples with good recoveries ranging from 93.4 to 98.2%. PMID:24798241

Ma, Yanhua; Zhang, Huige; Rahman, Zia Ur; Wang, Weifeng; Li, Xi; Chen, Hongli; Chen, Xingguo



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

E-print Network

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 ...

Bazant, Martin Z.


Electrokinetic Delivery of Biomolecules into Living Cells for Analysis of Cellular Regulation  

NASA Astrophysics Data System (ADS)

Current biomolecule-delivery systems, which function via pressure-driven flow, possess several significant limitations. We herein present a novel delivery method for biomolecules based on electrokinetic flow. The electrokinetic flow method uses capillaries to more easily deliver solutions than the pressure-driven flow method, which enables controllable injection of biomolecules into living cells. We characterized the electrokinetic flow of molecules to determine the parameters required for reproducible injections. Then, we successfully demonstrated the electrokinetic injection of a fluorescent DNA and dye solution into a living HeLa cell through a glass needle (1 µm in diameter). The monitoring of changes in ion current during the delivery process also allowed for the precise detection of penetration through the cell membrane with the tip of the needle.

Nagai, Moeto; Torimoto, Tatsuro; Miyamoto, Tokuma; Kawashima, Takahiro; Shibata, Takayuki



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

E-print Network

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.

Michele Campisi




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 ...



EPA Science Inventory

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


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

SciTech Connect

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




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

SciTech Connect

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

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



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

NASA Astrophysics Data System (ADS)

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.

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



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


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

Weng, Wuyin; Zheng, Huibin



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

SciTech Connect

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.

Menke, S. Matthew; Lindsay, Christopher D.; Holmes, Russell J. [Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455 (United States)



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

NASA Astrophysics Data System (ADS)

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

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



Incorporation of Solid Solution Alloying Effects into Polycrystal Modeling of Mg Alloys  

NASA Astrophysics Data System (ADS)

Discrepancies between the strength of slip systems determined directly from Mg single-crystal studies and those estimated from polycrystal simulations of Mg alloys are known to exist. These discrepancies have prohibited the direct use of single-crystal data within polycrystal models, ultimately leading to an increase in the number of adjustable parameters in such models and, accordingly, difficulties in extending such models to Mg alloys of industrial and technological relevance. In this work, a framework is introduced that eliminates these differences by accounting for continuum mechanical and physical metallurgical effects. With respect to the former, it is shown that a stiffer self-consistent grain-matrix interaction scheme than that commonly used better captures the behavior of textured Mg alloy AZ31. With respect to the latter, the impact of grain size and solute concentration on individual deformation modes is considered. Because of a lack of sufficient experimental data describing all possible deformation modes, only basal slip and prismatic slip are treated quantitatively. Of particular note is the strong solid solution strengthening of the basal slip mode and the moderate solute softening of the prismatic slip mode by the common alloying elements Al and Zn. An empirical model describing the Zn solute and temperature dependence of thermally activated prismatic slip is presented. The presented methodology provides a first attempt to eliminate the need for trial-and-error-based approach for determining the slip system flow stress parameters of polycrystal models. Areas where advances in the presented analysis may be attained are highlighted.

Raeisinia, Babak; Agnew, Sean R.; Akhtar, Ainul



Effectiveness of phototherapy incorporated into an exercise program for osteoarthritis of the knee: study protocol for a randomized controlled trial  

PubMed Central

Background Osteoarthritis is a chronic disease with a multifactor etiology involving changes in bone alignment, cartilage, and other structures necessary to joint stability. There is a need to investigate therapeutic resources that combine different wavelengths as well as different light sources (low-level laser therapy and light-emitting diode therapy) in the same apparatus for the treatment of osteoarthritis. The aim of the proposed study is to analyze the effect of the incorporation of phototherapy into a therapeutic exercise program for individuals with osteoarthritis of the knee. Methods/Design A double-blind, controlled, randomized clinical trial will be conducted involving patients with osteoarthritis of the knee. Evaluations will be performed using functional questionnaires before and after the treatment protocols, in a reserved room with only the evaluator and participant present, and no time constraints placed on the answers or evaluations. The following functional tests will also be performed: stabilometry (balance assessment), dynamometry (muscle strength of gluteus medius and quadriceps), algometry (pain threshold), fleximeter (range of motion), timed up-and-go test (functional mobility), and the functional reach test. The participants will then be allocated to three groups through a randomization process using opaque envelopes: exercise program, exercise program?+?phototherapy, or exercise program?+?placebo phototherapy, all of which will last for eight weeks. Discussion The purpose of this randomized clinical trial is to analyze the effect of the incorporation of phototherapy into a therapeutic exercise program for osteoarthritis of the knee. The study will support the practice based on evidence to the use of phototherapy in individuals with a diagnosis of osteoarthritis of the knee. Data will be published after the study is completed. Trial registration The protocol for this study has been submitted to Clinical Trials, registration number NCT02102347, on 29 March 2014. PMID:24919587



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

NASA Technical Reports Server (NTRS)

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

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



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

SciTech Connect

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

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



Recommendations for incorporating patient-reported outcomes into clinical comparative effectiveness research in adult oncology.  


Examining the patient's subjective experience in prospective clinical comparative effectiveness research (CER) of oncology treatments or process interventions is essential for informing decision making. Patient-reported outcome (PRO) measures are the standard tools for directly eliciting the patient experience. There are currently no widely accepted standards for developing or implementing PRO measures in CER. Recommendations for the design and implementation of PRO measures in CER were developed via a standardized process including multistakeholder interviews, a technical working group, and public comments. Key recommendations are to include assessment of patient-reported symptoms as well as health-related quality of life in all prospective clinical CER studies in adult oncology; to identify symptoms relevant to a particular study population and context based on literature review and/or qualitative and quantitative methods; to assure that PRO measures used are valid, reliable, and sensitive in a comparable population (measures particularly recommended include EORTC QLQ-C30, FACT, MDASI, PRO-CTCAE, and PROMIS); to collect PRO data electronically whenever possible; to employ methods that minimize missing patient reports and include a plan for analyzing and reporting missing PRO data; to report the proportion of responders and cumulative distribution of responses in addition to mean changes in scores; and to publish results of PRO analyses simultaneously with other clinical outcomes. Twelve core symptoms are recommended for consideration in studies in advanced or metastatic cancers. Adherence to methodologic standards for the selection, implementation, and analysis/reporting of PRO measures will lead to an understanding of the patient experience that informs better decisions by patients, providers, regulators, and payers. PMID:23071244

Basch, Ethan; Abernethy, Amy P; Mullins, C Daniel; Reeve, Bryce B; Smith, Mary Lou; Coons, Stephen Joel; Sloan, Jeff; Wenzel, Keith; Chauhan, Cynthia; Eppard, Wayland; Frank, Elizabeth S; Lipscomb, Joseph; Raymond, Stephen A; Spencer, Merianne; Tunis, Sean



Experimental investigation of electrokinetically generated in-plane vorticity in a microchannel  

Microsoft Academic Search

Electrokinetic generation of micro-flow patterns has advanced in recent years and received significant attention due to promising applications in biotechnology. Basic flow fields like bi-directional shear and out-of-plane vortices have been generated electrokinetically in microchannel liquid flow using various surface-charge patterns. In-plane vortex flows present a higher challenge since positive and negative charge regions on the same surface are required.

W. L. W. Hau; L. M. Lee; Y.-K. Lee; Man Wong; Y. Zohar



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

NASA Astrophysics Data System (ADS)

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

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



Transport of nanoparticles and reacting biomolecules in micro- and nanofluidic electrokinetic systems  

NASA Astrophysics Data System (ADS)

Micro and nanofluidic systems are ideal platforms for breakthrough bioanalytical tools. In particular, transport in nanoscale channels has been shown to be different than microscale systems because of unique coupled physics associated with wall interactions, electrokinetic surface phenomena and hydrodynamic confinement. Furthermore, understanding the effects of reaction kinetics during capillary electrophoresis is necessary for reliable bioanalytical tools with reacting species. We present experimental data and numerical simulation to elucidate the dominant physics at these lengths scales toward enabling nanofluidic bioanalytical devices. First, we present an experimental study to measure the effect channel height and ionic strength on the electrophoretic mobility of spherical nanoparticles and short single strand (ss) and double strand (ds) DNA with channel depths ranging from 20 microns to 100 nm. We find increased hydrodynamic drag in confinement, nanoparticle rotation effects for spherical analytes in sheer flows, non-uniform electro-osmotic velocity profiles, and electrostatic repulsion of thick electric double layers to be important effects on transport. Second, we present an experimental study of electrokinetic separations of short, complementary ss and dsDNA in microchannels. We find different phenomena are significant for the three different DNA lengths in the study (10nt, 20nt, and 50nt). Reaction kinetic effects are significant for the shortest length DNA, where the melting temperature is comparable to room temperature. For longer 20 and 50nt DNA, the melting temperatures are sufficiently high and reaction kinetic effects are constant. In addition, the 50 nt ssDNA contour length is greater than the persistence length and we find changes in electrophoretic mobility with ionic strength resulting from changes in conformation. Finally, we present numerical simulations of the previous study on separations of reacting DNA. Reaction kinetics can affect the equilibrium ratio of ss to dsDNA which influences transport by shifting the observed electrophoretic mobility of the dsDNA peak away from the true electrophoretic mobility. We perform parametric simulations of relevant parameters and find the initial plug width, analyte concentration and kinetic rate constants are the important parameters on the observed dsDNA peak. In addition, we use our model to determine reaction kinetic parameters (ie KD) of experimental data.

Wynne, Thomas Mikio


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

SciTech Connect

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

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



Micellar electrokinetic chromatographic determination of rosuvastatin in rabbit plasma and evaluation of its pharmacokinetics and interaction with niacin.  


A specific, accurate, precise and reproducible micellar electrokinetic chromatographic method was developed for in vitro and in vivo estimation of rosuvastatin, a synthetic and potent HMG-CoA inhibitor, in rabbit plasma. Further, its pharmacokinetics in the presence of niacin, which could be co-administered for monitoring of severe hypercholestremia, was investigated. The assay procedures involved simple liquid-liquid extraction of rosuvastatin and internal standard, atorvastatin, from a small plasma volume directly into acetonitrile. The organic layer was separated and evaporated under a gentle stream of nitrogen. The residue was reconstituted in the mobile phase and injected electrokinetically into electropherosis system. The background electrolyte consisted of borate buffer (25.0?mm, pH?9.5), 10.0% organic modifier (5.0% methanol?+?5.0% acetonitrile) and 25.0?mm sodium dodecyl sulfate at 20.0?kV applied voltage and 215.0?nm detection wavelength for the effective separation of rosuvastatin, niacin and atorvastatin. PMID:24828212

El-Kommos, Michael E; Mohamed, Niveen A; Ali, Hassan R H; Abdel Hakiem, Ahmed F



A combination of electrokinetics and Pd/Fe PRB for the remediation of pentachlorophenol-contaminated soil  

NASA Astrophysics Data System (ADS)

Electrokinetic (EK) remediation of pentachlorophenol (PCP)-contaminated soil is difficult because PCP dissociates at different pH values along soil column and shows different transport behaviors near anode and cathode. In the present study, a permeable reactive barrier (PRB) filled with reactive Pd/Fe particles was installed between anode and cathode to reach the dechlorination of PCP during its EK movement. When PRB was installed at the position of 0.3 (normalized distance from anode), PCP in the section from anode to PRB could transport through PRB, while PCP in the section from cathode to PRB was accumulated near PRB. PCP was hardly dechlorinated by PRB wherein high pH was reached. When PRB was installed at the position of 0.5 and the pH in the PRB was decreased by periodical injection of HAc, 49% of PCP was removed, and 22.9% was recovered as phenol which was mostly collected in catholyte. The mechanism of PCP removal was proposed as the EK movement of PCP into the PRB compartment, the complete dechlorination of PCP to phenol by Pd/Fe in the PRB compartment, and the subsequent removal of phenol by electroosmosis. This study proved that the combination of electrokinetics and Pd/Fe PRB was effective for the remediation of PCP-contaminated soil.

Li, Zhirong; Yuan, Songhu; Wan, Jinzhong; Long, Huayun; Tong, Man



Evaluation of a dual-cyclodextrin phase variant of capillary electrokinetic chromatography for separations of nonionizable solutes  

SciTech Connect

A capillary electrokinetic chromatography technique is described that employs neutral cyclodextrins (CDs) as a primary phase, transported with electroosmotic flow, and charged CDs as an electrophoretically mediated secondary phase. Neutral, hydrophobic solutes are separated on the basis of their differential distribution between these CD phases. The technique resembles micellar electrokinetic capillary chromatography (MECC) with regard to instrumentation and the fundamental relationships for resolution and capacity factor, which are influenced by the existence of a finite elution window. Conversely, the CD technique offers unique and beneficial characteristics when compared to MECC. Efficiency, selectivity, and system retention are evaluated on the basis of separations of polyaromatic hydrocarbons (PAHs). Efficiency is comparable to that of MECC (> 10{sup 5} plates/m). The specificity associated with solute-CD inclusion complexation provides elution orders for PAHs that do not follow the hydrophobicity trends of MECC. Moreover, since the CD phases are largely noninteractive, complex CD systems can be used to enhance selectivity. Capacity factors can be altered in a convenient and predictable fashion simply by changing the CD phase ratio. The technique is rather robust with regard to the use of running buffers containing organic solvents; the effects or organic modifier and pH on system retention are demonstrated. 19 refs., 4 figs., 1 tab.

Sepaniak, M.J.; Copper, C.L.; Whitaker, K.W.; Anigbogu, V.C. [Univ. of Tennessee, Knoxville, TN (United States)



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

NASA Astrophysics Data System (ADS)

One of the greatest sources of uncertainty in the science of anthropogenic climate change is from aerosol-cloud interactions. The activation of aerosols into cloud droplets is a direct microphysical linkage between aerosols and clouds; parameterizations of this process link aerosol with cloud condensation nuclei (CCN) and the resulting indirect effects. Small differences between parameterizations can have a large impact on the spatiotemporal distributions of activated aerosols and the resulting cloud properties. In this work, we incorporate a series of aerosol activation schemes into the Community Atmosphere Model version 5.1.1 within the Community Earth System Model version 1.0.5 (CESM/CAM5) which include factors such as insoluble aerosol adsorption and giant cloud condensation nuclei (CCN) activation kinetics to understand their individual impacts on global-scale cloud droplet number concentration (CDNC). Compared to the existing activation scheme in CESM/CAM5, this series of activation schemes increase the computation time by ~10% but leads to predicted CDNC in better agreement with satellite-derived/in situ values in many regions with high CDNC but in worse agreement for some regions with low CDNC. Large percentage changes in predicted CDNC occur over desert and oceanic regions, owing to the enhanced activation of dust from insoluble aerosol adsorption and reduced activation of sea spray aerosol after accounting for giant CCN activation kinetics. Comparison of CESM/CAM5 predictions against satellite-derived cloud optical thickness and liquid water path shows that the updated activation schemes generally improve the low biases. Globally, the incorporation of all updated schemes leads to an average increase in column CDNC of 150% and an increase (more negative) in shortwave cloud forcing of 12%. With the improvement of model-predicted CDNCs and better agreement with most satellite-derived cloud properties in many regions, the inclusion of these aerosol activation processes should result in better predictions of radiative forcing from aerosol-cloud interactions.

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



Growth Rate Dependence of Mg, Sr, and U Incorporation Into Aragonite: Experimental Constraints on the Origin of Vital Effects  

NASA Astrophysics Data System (ADS)

The elemental composition of biogenic carbonates provides an increasingly significant proportion of the climate proxy data used to understand Earth's climate history. However, there is abundant evidence to indicate that factors other than temperature influence the incorporation of trace elements into the skeletons of marine invertebrates. Understanding the origin of these "vital effects" is, therefore, one important goal of biomineralization studies. Here we present results from precipitation experiments designed to elucidate the role of variations in crystal growth rate (extension rate) on the composition of biogenic aragonite. While our experimental results show clear evidence for growth rate dependence on the incorporation of both Mg and U into abiogenic aragonite, comparisons with biogenic aragonite demonstrate that this effect does not have a major influence on the composition of the skeletons of scleractinian corals. Sr and Mg partitioning between aragonite and seawater was studied at 25°C. U partitioning between aragonite and solution of NH4-Mg-Ca-U-Cl was determined at 22°C. Linear growth rates of the crystals were constrained by addition of ^{84}Sr, ^{88}Sr or Dy spikes into the growth solution at different times during each experiment. Location of spikes within crystals was determined to within ±5 microns by SIMS ion microprobe. Our data indicate that the Mg exchange coefficient (Kd^{Mg}=[Mg/Ca] ^{crystal}/[Mg/Ca]^{fluid}) increased from 3×10-4 to 12×10-4 as crystal growth rate increased from 2 to 117 microns/day. Kd^{U} increased from 3.5±1.5×10-2 to 0.95±0.1 as crystal growth rate increased from 3.1 to 5.5 microns/day and then remained approximately constant up to growth rates of at least 15.4 microns/day. In contrast KdSr was independent of crystal growth rate over the studied range (Kd^{Sr} = 1.2±0.1). Comparisons of our experimental results with the compositional variations found in scleractinian corals indicate that changes in Kd related to variations in growth rate are not sufficient to explain "vital effects" in coral skeleton. For example, Sinclair (2005) reported Sr, Mg, and U variations in Porites skeleton that cannot be explained by temperature. These variations are strongly correlated with one another. Because Kd^{Sr} shows no significant dependence on growth rate, compositional variations such as these are not explicable in terms of variations in crystal growth rate. References: Sinclair, D. J. (2005) Geochim Cosmochim Acta 69, 3265-3284.

Gabitov, R. I.; Cohen, A. L.; Gaetani, G. A.; Holcomb, M.; Watson, E. B.



Modeling EDTA enhanced electrokinetic remediation of lead contaminated soils.  


Electrokinetic extraction has been tested for lead removal from Algerian contaminated soils. For this purpose, a chelating reagent (EDTA, 0.1M) has been injected into the catholyte. This procedure is expected to enhance the process by desorption of the contaminant and formation of new mobile species negatively charged. A mathematical model based on Nernst-Planck theory has also been developed to predict the evolution of lead distribution across the soil as a function of time. The results of several experiments carried out on various duration (10, 20 and 40 days) have shown the importance on treatment efficiency of pollution age and contaminant speciation as determined by sequential chemical extraction. PMID:16054906

Amrate, S; Akretche, D E



Electrokinetic treatment of firing ranges containing tungsten-contaminated soils.  


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

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



Entropic Electrokinetics: Recirculation, Particle Separation, and Negative Mobility  

NASA Astrophysics Data System (ADS)

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.

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



Mechanistic studies of partial-filing micellar electrokinetic chromatography  

SciTech Connect

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

Nelson, W.M.; Lee, C.S. [Ames National Lab., IA (United States)] [Ames National Lab., IA (United States); [Iowa State Univ., Ames, IA (United States)



Synthesis and Carbonic Anhydrase Isoenzymes I, II, IX, and XII Inhibitory Effects of Dimethoxybromophenol Derivatives Incorporating Cyclopropane Moieties.  


Cyclopropylcarboxylic acids and esters and cyclopropylmethanols incorporating bromophenol moieties were investigated as inhibitors of the carbonic anhydrase enzyme (CA; EC 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

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



Effect of P Incorporation on Aggregation of Nanocrystallites in Amorphous and Nanocrystalline Mixed-Phase Silicon Thin Films  

SciTech Connect

We report the effects of P incorporation on the nanometer-scale structural and electrical properties of amorphous and nanocrystalline mixed-phase Si:H films. In the intrinsic and weakly P-doped (3 x 10{sup 18}at/cm{sup 3}) films, the nanocrystallites aggregate to cone-shaped structures. Conductive atomic force microscopy images showed high current flows through the nanocrystalline cones and a distinct two-phase structure in the micrometer range. Adding PH{sub 3} into the processing gas moved the amorphous/nanocrystalline transition to a higher hydrogen dilution ratio required for achieving a similar Raman crystallinity. In a heavily P-doped (2 x 10{sup 21} at/cm{sup 3}) film, the nanocrystalline aggregation disappeared, where isolated grains of nanometer sizes were distributed throughout the amorphous matrix. The heavily doped mixed-phase film with 5-10% crystal volume fraction showed a dramatic increase in conductivity. We offer an explanation for the nanocrystalline cone formation based on atomic hydrogen enhanced surface diffusion model, and propose that the coverage of P-related radicals on the existing nanocrystalline surface during film growth and the P segregation in grain boundaries are responsible for preventing new nucleation on the surface of the existing nanocrystallites, resulting in nanocrystallites dispersed throughout the amorphous matrix.

Jiang, C.-S.; Yan, B.; Yan, Y.; Teplin, C. W.; Reedy, R.; Mountinho, H. R.; Al-Jassim, M. M.; Yang, J.; Guha, S.



[Effects of long-term manure and crop residues incorporation on yield and phosphorus saturation in a paddy soil].  


An 8-year field experiment was conducted in the Taihu Lake region of eastern China to investigate the effects of incorporation of straw and manure on the yield and phosphorus (P) accumulation in the paddy soil, and to evaluate the potential risk of P loss from soil to environment. The experiment had four fertilization treatments, i. e., chemical fertilizers alone (NPK), chemical fertilizers plus rice/wheat straw (NPK + S), chemical fertilizers plus 7.5 t x (hm2 x a)(-1) wet pig manure (NPK + M7.5), and chemical fertilizers plus 15.0 t x (hm2 x a)(-1) wet pig manure (NPK + M15). Among the four treatments, no significant differences were observed in the yield of rice or wheat. Long-term application of chemical fertilizers plus pig manure significantly increased the soil total P, the degree of P saturation (DPS), and the concentration of extractable P forms, including Olsen-P, Mehlich 3 extractable P, CaCl2 extractable P, and water extractable P, which became a potential source of eutrophication in Taihu Lake. In contrast to chemical fertilizers plus pig manure, there were no significant differences in the concentrations of extractable P forms between the NPK + S and NPK treatments. We concludes that chemical fertilizers [P 45 kg x (hm2 x a)(-1)] plus rice/wheat straw should be recommended in the paddy soil in the Taihu Lake region under the rice-wheat rotation system. PMID:24191569

Yan, Xiao; Wang, De-Jian; Zhang, Gang; Ran, Jing; Zheng, Ji-Cheng



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

NASA Astrophysics Data System (ADS)

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

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



An experimental test of new theoretical models for the electrokinetic properties of biological membranes. The effect of UO2++ and tetracaine on the electrophoretic mobility of bilayer membranes and human erythrocytes  

PubMed Central

For a large smooth particle with charges at the surface, the electrophoretic mobility is proportional to the zeta potential, which is related to the charge density by the Gouy-Chapman theory of the diffuse double layer. This classical model adequately describes the dependence of the electrophoretic mobility of phospholipid vesicles on charge density and salt concentration, but it is not applicable to most biological cells, for which new theoretical models have been developed. We tested these new models experimentally by measuring the effect of UO2++ on the electrophoretic mobility of model membranes and human erythrocytes in 0.15 M NaCl at pH 5. We used UO2++ for these studies because it should adsorb specifically to the bilayer surface of the erythrocyte and should not change the density of fixed charges in the glycocalyx. Our experiments demonstrate that it forms high-affinity complexes with the phosphate groups of several phospholipids in a bilayer but does not bind significantly to sialic acid residues. As observed previously, UO2++ adsorbs strongly to egg phosphatidylcholine (PC) vesicles: 0.1 mM UO2++ changes the zeta potential of PC vesicles from 0 to +40 mV. It also has a large effect on the electrophoretic mobility of vesicles formed from mixtures of PC and the negative phospholipid phosphatidylserine (PS): 0.1 mM UO2++ changes the zeta potential of PC/PS vesicles (10 mol % PS) from -13 to +37 mV. In contrast, UO2++ has only a small effect on the electrophoretic mobility of either vesicles formed from mixtures of PC and the negative ganglioside GM1 or erythrocytes: 0.1 mM UO2++ changes the apparent zeta potential of PC/GM1 vesicles (17 mol % GM1) from -11 to +5 mV and the apparent zeta potential of erythrocytes from -12 to -4 mV. The new theoretical models suggest why UO2++ has a small effect on PC/GM1 vesicles and erythrocytes. First, large groups (e.g., sugar moieties) protruding from the surface of the PC/GM1 vesicles and erythrocytes exert hydrodynamic drag. Second, charges at the surface of a particle (e.g., adsorbed UO2++) exert a smaller effect on the mobility than charges located some distance from the surface (e.g., sialic acid residues). PMID:3794637



Electrokinetic Phenomena in Nano-Colloids and Nano-Fluidics All lectures will be held at the  

E-print Network

Electrokinetic Phenomena in Nano-Colloids and Nano-Fluidics All lectures will be held:00-15:30 Steffen Hardt Isotachophoresis in Microchannels: Electrokinetic Transport at the Interface between Two and Dielectric Fluid Suspensions 18:15-19:30 Reception hosted by the Center for Mathematical Sciences Monday ­ 20


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

NASA Astrophysics Data System (ADS)

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.

Contento, Nicholas M.


Electrokinetic desalination using honeycomb carbon nanotubes (HC-CNTs): a conceptual study by molecular simulation.  


A new concept of electrokinetic desalination using a CNT honeycomb is presented through molecular dynamics simulation. The preferential translocation of ions towards the outlets near two electrodes was realized by applying an electric field perpendicular to bulk fluid flow in a CNT network, which, in the meantime, generated deionized water flux discharged from the central outlets. The effects of the major factors such as electric field strength, numbers of separation units, diameter of CNT, and ion concentration on the desalination were examined. It was shown that over 95% salt rejection and around 50% fresh water recovery were achieved by the presented module by applying an electric field of 0.8 V nm(-1). CNT diameter, which is critical to ion rejection without the electric field, had a marginal effect on the desalination of this new module when a strong electric field was applied. The desalination was also not sensitive to ion concentration, indicating its excellent workability for a wide range of water salinity, e.g. from brackish water to seawater. A potential of mean force profile revealed a free energy barrier as large as 2.0-6.0 kcal mol(-1) for ions to move opposite to the implemented electrical force. The simulation confirmed the high potential of the CNT honeycomb in water desalination. PMID:25092215

Chen, Qile; Kong, Xian; Li, Jipeng; Lu, Diannan; Liu, Zheng



Effects of magnetic nanoparticle-incorporated human bone marrow-derived mesenchymal stem cells exposed to pulsed electromagnetic fields on injured rat spinal cord.  


Transplanting mesenchymal stem cells into injured lesions is currently under study as a therapeutic approach for spinal cord injury. In this study, the effects of a pulsed electromagnetic field (PEMF) on injured rat spinal cord were investigated in magnetic nanoparticle (MNP)-incorporated human bone marrow-derived mesenchymal stem cells (hBM-MSCs). A histological analysis revealed significant differences in MNP-incorporated cell distribution near the injured site under the PEMF in comparison with that in the control group. We confirmed that MNP-incorporated cells were widely distributed in the lesions under PEMF. The results suggest that MNP-incorporated hBM-MSCs were guided by the PEMF near the injured site, and that PEMF exposure for 8 H per day over 4 weeks promoted behavioral recovery in spinal cord injured rats. The results show that rats with MNP-incorporated hBM-MSCs under a PEMF were more effective on the Basso, Beattie, and Bresnahan behavioral test and suggest that the PEMF enhanced the action of transplanted cells for recovery of the injured lesion. PMID:24033637

Cho, Hyunjin; Choi, Yun-Kyong; Lee, Dong Heon; Park, Hee Jung; Seo, Young-Kwon; Jung, Hyun; Kim, Soo-Chan; Kim, Sung-Min; Park, Jung-Keug



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

SciTech Connect

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.

Souma, Satofumi, E-mail:; Ueyama, Masayuki; Ogawa, Matsuto [Department of Electrical and Electronic Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan)



Biosynthetic incorporation of tryptophan analogues into staphylococcal nuclease: effect of 5-hydroxytryptophan and 7-azatryptophan on structure and stability.  

PubMed Central

5-Hydroxytryptophan (5HW) and 7-azatryptophan (7AW) are analogue of tryptophan that potentially can be incorporated biosynthetically into proteins and used as spectroscopic probes for studying protein-DNA and protein-protein complexes. The utility of these probes will depend on the extent to which they can be incorporated and the demonstration that they cause minimal perturbation of a protein's structure and stability. To investigate these factors in a model protein, we have incorporated 5HW and 7AW biosynthetically into staphylococcal nuclease A, using a trp auxotroph Escherichia coli expression system containing the temperature-sensitive lambda cI repressor, Both tryptophan analogues are incorporated into the protein with good efficiency. From analysis of absorption spectra, we estimate approximately 95% incorporation of 5HW into position 140 of nuclease, and we estimate approximately 98% incorporation of 7AW, CD spectra of the nuclease variants are similar to that of the tryptophan-containing protein, indicating that the degree of secondary structure is not changed by the tryptophan analogues. Steady-state fluorescence data show emission maxima of 338 nm for 5HW-containing nuclease and 355 nm for 7AW-containing nuclease. Time-resolved fluorescence intensity and anisotropy measurements indicate that the incorporated 5HW residue, like tryptophan at position 140, has a dominant rotational correlation time that is approximately the value expected for global rotation of the protein. Guanidine-hydrochloride-induced unfolding studies show the unfolding transition to be two-state for 5HW-containing protein, with a free energy change for unfolding that is equal to that of the tryptophan-containing protein. In contrast, the guanidine-hydrochloride-induced unfolding of 7AW-containing nuclease appears to show a non-two-state transition, with the apparent stability of the protein being less than that of the tryptophan form. PMID:9070451

Wong, C. Y.; Eftink, M. R.



Incorporation of genetic model parameters for cost-effective designs of genetic association studies using DNA pooling  

PubMed Central

Background Studies of association methods using DNA pooling of single nucleotide polymorphisms (SNPs) have focused primarily on the effects of "machine-error", number of replicates, and the size of the pool. We use the non-centrality parameter (NCP) for the analysis of variance test to compute the approximate power for genetic association tests with DNA pooling data on cases and controls. We incorporate genetic model parameters into the computation of the NCP. Parameters involved in the power calculation are disease allele frequency, frequency of the marker SNP allele in coupling with the disease locus, disease prevalence, genotype relative risk, sample size, genetic model, number of pools, number of replicates of each pool, and the proportion of variance of the pooled frequency estimate due to machine variability. We compute power for different settings of number of replicates and total number of genotypings when the genetic model parameters are fixed. Several significance levels are considered, including stringent significance levels (due to the increasing popularity of 100 K and 500 K SNP "chip" data). We use a factorial design with two to four settings of each parameter and multiple regression analysis to assess which parameters most significantly affect power. Results The power can increase substantially as the genotyping number increases. For a fixed number of genotypings, the power is a function of the number of replicates of each pool such that there is a setting with maximum power. The four most significant parameters affecting power for association are: (1) genotype relative risk, (2) genetic model, (3) sample size, and (4) the interaction term between disease and SNP marker allele probabilities. Conclusion For a fixed number of genotypings, there is an optimal number of replicates of each pool that increases as the number of genotypings increases. Power is not substantially reduced when the number of replicates is close to but not equal to the optimal setting. PMID:17634103

Ji, Fei; Finch, Stephen J; Haynes, Chad; Mendell, Nancy R; Gordon, Derek



Tumoricidal effects of etoposide incorporated into solid lipid nanoparticles after intraperitoneal administration in Dalton's lymphoma bearing mice.  


The tumoricidal effects of etoposide incorporated into lipid nanoparticles after single-dose administration were investigated in Dalton's lymphoma ascites bearing mice. Etoposide and its nanoparticle formulations were administered intraperitoneally, and the cell cycle perturbation, cytogenetic damage, cell death (apoptosis), tumor regression, and animal survival were investigated as parameters of response with time. The tumor burden of mice treated with etoposide and its nanoparticle formulations decreased significantly (P < .001) compared with the initial up to 4 to 6 days, followed by an increase at later time intervals. Of the 3 different formulations, the survival time of mice was higher when treated with etoposide-loaded tripalmitin (ETP) nanoparticles, followed by etoposide-loaded glycerol monostearate (EGMS) (27.3%) and etoposide-loaded glycerol distearate (EGDS) (27.3%) compared with free etoposide. Cell cycle analysis revealed the hypodiploid peak (sub G0/G1 cell population) as well as G2 arrest in mice treated with etoposide and its nanoparticle formulations. The frequency of dead cells treated with the nanoparticle formulations remained high even after 8 days of treatment compared with free etoposide. The mice treated with nanoparticle formulations exhibited hypodiploid peaks and reduced S phase even 8 days after treatment, whereas the free etoposide-treated mice showed decrease in apoptosis after 3 days of treatment. The apoptotic frequency in cells 17 days after treatment was in the order of ETP > EGMS > EGDS > etoposide. The experimental results indicated that among the 3 nanoparticle formulations studied, the ETP nanoparticles showed greater and prolonged apoptotic induction properties, resulting in the higher increase in survival time of tumor bearing mice. PMID:16796375

Reddy, Lakkireddy Harivardhan; Adhikari, Jawahar Singh; Dwarakanath, Bilikere Srinirasa Rao; Sharma, Rakesh Kumar; Murthy, Rayasa Ramachandra



Effect of iodide on glucose oxidation and /sup 32/P incorporation into phospholipids stimulated by different agents in dog thyroid slices  

SciTech Connect

Since iodide (I-) inhibits TSH stimulation of cAMP formation, which mediates most of the effects of the hormone, it has been assumed that this accounts for the inhibitory action of iodide on the thyroid. However, TSH stimulation of 32P incorporation into phospholipids and stimulation of thyroid metabolism by other agonists, such as carbachol, phorbol esters, and ionophore A23187, is not cAMP mediated. The present studies examined the effect of iodide on stimulation of glucose oxidation and 32P incorporation into phospholipids by TSH and other agonists to determine if the inhibition of cAMP formation was responsible for the action of iodide. Preincubation of dog thyroid slices for 1 h with iodide (10(-4) M) inhibited TSH-, (Bu)2cAMP-, carbachol-, methylene blue-, 12-O-tetradecanoyl phorbol-13-acetate-, ionophore A23187-, prostaglandin E1-, and cholera toxin-stimulated glucose oxidation. I- also inhibited the stimulation by TSH, 12-O-tetradecanoyl phorbol-13-acetate, carbachol, and ionophore A23187 of 32P incorporation into phospholipids. The inhibition was similar whether iodide was added 2 h before or simultaneously with the agonist. I- itself sometimes stimulated basal glucose oxidation, but had no effect on basal 32P incorporation into phospholipids. The effects of iodide on basal and agonist-stimulated thyroid metabolism were blocked by methimazole (10(-3) M). When dog thyroid slices were preloaded with 32PO4 or (1-14C)glucose, the iodide inhibition of agonist stimulation disappeared, suggesting that the effect of iodide involves the transport process. In conclusion, I- inhibited stimulation of glucose oxidation and 32P incorporation into phospholipids by all agonists, indicating that the effect is independent of the cAMP system and that iodide autoregulation does not only involve this system. Oxidation and organification of iodide are necessary for the inhibition.

Tseng, F.Y.; Rani, C.S.; Field, J.B.



In vitro effect of liposome-incorporated valinomycin on growth and macromolecular synthesis of normal and ras -transformed 3T3 cells  

Microsoft Academic Search

Summary Valinomycin is a depsipeptide antibiotic that selectively translocates potassium ion across biologic membranes. This drug has been reported to display antitumor effects, but its use has been limited by its extreme toxicity. However, its incorporation into lipid vesicles (liposomes) has resulted in a reduction in toxicity and in the enhancement of the drug's therapeutic index [4]. As a preliminary

Sayed S. Daoud; R. L. Juliano



Interactions of arbuscular-mycorrhizal fungi and Bacillus strains and their effects on plant growth, microbial rhizosphere activity (thymidine and leucine incorporation) and fungal biomass (ergosterol and chitin)  

Microsoft Academic Search

The effects of two Bacillus strains (Bacillus pumillus and B. licheniformis) on Medicago sativa plants were determined in single or dual inoculation with three arbuscular-mycorrhizal (AM) fungi and compared to P-fertilization. Shoot and root plant biomass, values of thymidine and leucine incorporation as well as ergosterol and chitin in rhizosphere soil were evaluated to estimate metabolic activity and fungal biomass,

A Medina; A Probanza; F. J Gutierrez Mañero; R Azcón



The effect of the method of incorporation of Trifolium resupinatum L. and Vicia villosa Roth. Residues in the Soil on the Performance of a Succeeding Cereal Crop  

Microsoft Academic Search

In this study, roots, shoots and whole crop stand of persian clover and hairy vetch grown as green fallow were incorporated in the soil either in a conventional manner (autumn ploughing) or following conservation tillage methods (stubble cultivation, minimum tillage). The after-effect on cereal crop performance was followed for two successive years. The impact on grain yield, grain characteristics and

R. T. Poutala; A. Hannukkala



The effects of guided inquiry instruction incorporating a cooperative learning approach on university students' achievement of acid and bases concepts and attitude toward guided inquiry instruction  

Microsoft Academic Search

The purpose of this study was to investigate the effects of guided inquiry instruction incorporating with cooperative learning environment on University students' achievement of acid and bases concepts and attitude toward guided inquiry instruction. The subject of this study consisted of 55 first year University students from two intact classes of a Chemistry Course instructed by the same teacher. One

Ibrahim Bilgin


Effect of Hyaluronic Acid Incorporation Method on the Stability and Biological Properties of Polyurethane-Hyaluronic Acid Biomaterials  

PubMed Central

The high failure rate of small diameter vascular grafts continues to drive the development of new materials and modification strategies that address this clinical problem, with biomolecule incorporation typically achieved via surface-based modification of various biomaterials. In this work, we examined whether the method of biomolecule incorporation (i.e., bulk vs. surface modification) into a polyurethane (PU) polymer impacted biomaterial performance in the context of vascular applications. Specifically, hyaluronic acid (HA) was incorporated into a poly(ether urethane) via bulk copolymerization or covalent surface tethering, and the resulting PU-HA materials characterized with respect to both physical and biological properties. Modification of PU with HA by either surface or bulk methods yielded materials that, when tested under static conditions, possessed no significant differences in their ability to resist protein adsorption, platelet adhesion, and bacterial adhesion, while supporting endothelial cell culture. However, only bulk-modified PU-HA materials were able to fully retain these characteristics following material exposure to flow, demonstrating a superior ability to retain the incorporated HA and minimize enzymatic degradation, protein adsorption, platelet adhesion, and bacterial adhesion. Thus, despite bulk methods rarely being implemented in the context of biomolecule attachment, these results demonstrate improved performance of PU-HA upon bulk, rather than surface, incorporation of HA. Although explored only in the context of PU-HA, the findings revealed by these experiments have broader implications for the design and evaluation of vascular graft modification strategies. PMID:24276670

Ruiz, Amaliris; Rathnam, Kashmila R.; Masters, Kristyn S.



Effect of hyaluronic acid incorporation method on the stability and biological properties of polyurethane-hyaluronic acid biomaterials.  


The high failure rate of small diameter vascular grafts continues to drive the development of new materials and modification strategies that address this clinical problem, with biomolecule incorporation typically achieved via surface-based modification of various biomaterials. In this work, we examined whether the method of biomolecule incorporation (i.e., bulk versus surface modification) into a polyurethane (PU) polymer impacted biomaterial performance in the context of vascular applications. Specifically, hyaluronic acid (HA) was incorporated into a poly(ether urethane) via bulk copolymerization or covalent surface tethering, and the resulting PU-HA materials characterized with respect to both physical and biological properties. Modification of PU with HA by either surface or bulk methods yielded materials that, when tested under static conditions, possessed no significant differences in their ability to resist protein adsorption, platelet adhesion, and bacterial adhesion, while supporting endothelial cell culture. However, only bulk-modified PU-HA materials were able to fully retain these characteristics following material exposure to flow, demonstrating a superior ability to retain the incorporated HA and minimize enzymatic degradation, protein adsorption, platelet adhesion, and bacterial adhesion. Thus, despite bulk methods rarely being implemented in the context of biomolecule attachment, these results demonstrate improved performance of PU-HA upon bulk, rather than surface, incorporation of HA. Although explored only in the context of PU-HA, the findings revealed by these experiments have broader implications for the design and evaluation of vascular graft modification strategies. PMID:24276670

Ruiz, Amaliris; Rathnam, Kashmila R; Masters, Kristyn S



Effect of hypoxia on the incorporation of (2-3H) glycerol and (1-14C(-palmitate into lipids of various brain regions  

SciTech Connect

The lipid metabolism in guinea pig brain after intermittent hypoxia, prolonged for 80 hrs, was markedly impaired. The in vivo incorporation of (2-3H) glycerol and (1-14C) palmitate into lipids of microsomes, mitochondria, myelin, and synaptosomes, purified form cerebral hemispheres, was significantly lower in the hypoxic animals than in the controls. The same effect was observed on the incorporation of labeled precursors into lipids of mitochondria purified from cerebellum and brainstem. In particular, the labeling of th major phospholipids present - ie, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) - in the mitochondria of the three brain regions examined decreased after hypoxic treatment.

Alberghina, M.; Giuffrida, A.M.



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

SciTech Connect

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

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



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


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

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



Scalable surface area characterization by electrokinetic analysis of complex anion adsorption.  


By means of the in situ electrokinetic assessment of aqueous particles in conjunction with the addition of anionic adsorbates, we develop and examine a new approach to the scalable characterization of the specific accessible surface area of particles in water. For alumina powders of differing morphology in mildly acidic aqueous suspensions, the effective surface charge was modified by carboxylate anion adsorption through the incremental addition of oxalic and citric acids. The observed zeta potential variation as a function of the proportional reagent additive was found to exhibit inverse hyperbolic sine-type behavior predicted to arise from monolayer adsorption following the Grahame-Langmuir model. Through parameter optimization by inverse problem solving, the zeta potential shift with relative adsorbate addition revealed a nearly linear correlation of a defined surface-area-dependent parameter with the conventionally measured surface area values of the powders, demonstrating that the proposed analytical framework is applicable for the in situ surface area characterization of aqueous particulate matter. The investigated methods have advantages over some conventional surface analysis techniques owing to their direct applicability in aqueous environments at ambient temperature and the ability to modify analysis scales by variation of the adsorption cross section. PMID:25495551

Hanaor, Dorian A H; Ghadiri, Maliheh; Chrzanowski, Wojciech; Gan, Yixiang



A Novel Micellar Electrokinetic Chromatographic Method for Separation of Metal-DDTC Complexes  

PubMed Central

Micellar electrokinetic chromatography (MEKC) was examined for the separation and determination of Mo(VI), Cr(VI), Ni(II), Pd(II), and Co(III) as diethyl dithiocarbamate (DDTC) chelates. The separation was achieved from fused silica capillary (52?cm?×?75??m?id) with effective length 40?cm, background electrolyte (BGE) borate buffer pH?9.1 (25?mM), CTAB 30% (100?mM), and 1% butanol in methanol (70?:?30?:?5?v/v/v) with applied voltage of ?10?kV using reverse polarity. The photodiode array detection was achieved at 225?nm. The linear calibration for each of the element was obtained within 0.16–10??g/mL with a limit of detection (LOD) 0.005–0.0167??g/mL. The separation and determination was repeatable with relative standard deviation (RSD) within 2.4–3.3% (n = 4) in terms of migration time and peak height/peak area. The method was applied for the determination of Mo(VI) from potatoes and almond, Ni(II) from hydrogenated vegetable oil, and Co(III) from pharmaceutical preparations with RSD within 3.9%. The results obtained were checked by standard addition and rechecked by atomic absorption spectrometry. PMID:22649320

Mallah, Arfana; Memon, Saima Q.; Solangi, Amber R.; Memon, Najma; Abbassi, Kulsoom; Khuhawar, Muhammad Yar



Improved protein detection on an AC electrokinetic quartz crystal microbalance (EKQCM).  


Microscale electrodes supplied with an AC field can generate rotational fluid patterns known as AC electroosmosis. In the present study, this effect was used to improve antibody binding on a biosensor surface. Antibodies, like many other large, slow moving biomolecules, tend to suffer from transport limitations during a reaction with a surface-bound receptor. Stirring such reactions with AC electroosmosis can alleviate this transport limitation by bringing fresh reagent to the surface. For the first time, the use of this phenomenon was used to improve the capture of protein on a sensor. Directly adsorbed antibodies were bound to the surface of specially modified quartz crystal microbalances, known as electrokinetic QCMs (EKQCMs) and the signal was enhanced by about 5.6 times. Modification of the QCM resulted in little reduction of quality factor (from ? 5.3 k to ? 4.6k) and an increased sensitivity to viscosity changes (151%). Full immunoassays performed on electrodes fabricated on glass surfaces were used to ensure antibody function was not significantly degraded by the enhancement technique. PMID:21353520

Hart, Robert; Ergezen, Erten; Lec, Ryszard; Noh, Hongseok Moses



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


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

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



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

PubMed Central

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

Edwards, Judson Vincent; Prevost, Nicolette



Highly efficient separation of isomeric epoxy fatty acids by micellar electrokinetic chromatography.  


A capillary electrophoresis (CE) method has been developed for simple and direct separation of cis- and trans-12,13-epoxy-9(Z)-octadecenoic acid and 9,10-epoxy-12(Z)-octadecenoic acid isomers. Separation was performed in micellar electrokinetic capillary chromatography (MEKC) using a buffer consisting of 25 mM borate (pH 9.20), 10 mM sodium dodecyl sulfate (SDS) and 10% v/v acetonitrile. The key variables, concentrations of SDS and organic modifier, were optimized by the application of a factorial experimental design. The use of a low micellar concentration, just above critical micelle concentration (CMC), in a background electrolyte containing an organic modifier not only made it possible to dissolve and separate highly hydrophobic fatty acid isomers, but also resulted in improved separation efficiency and selectivity. Separation efficiency up to 4 x 10(5) theoretical plates/m was achieved under an optimized condition. Also investigated were the influence of temperature on separation and the effect of organic modifier concentration on the dynamic exchange of the analytes between micelles and the bulk of the buffer solution. Direct UV was applied for detection of the fatty acids. PMID:10065969

Wan, H; Blomberg, L G; Hamberg, M



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


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. PMID:23944561

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



Field-enhanced electrokinetic charge separation induced by thermocapillarity-driven flow in a liquid film  

NASA Astrophysics Data System (ADS)

Thermocapillary stresses acting tangentially to the interface of a thin liquid film in a wide slot subjected to a lateral thermal gradient induce a rotational flow pattern. We demonstrate analytically and numerically for an electrolyte as working fluid that this flow can be used to separate charges and induce a streaming potential based on the electrokinetic effect, converting thermal to electric energy. The charge separation efficiency is commonly spoiled by the circumstance that the excess ions accumulate in direct vicinity of the wall where frictional losses are highest. As an alternative, we impose a traverse electric field across the film so that excess ions also accumulate at the gas-liquid interface where the highest flow velocities occur. No power is needed to maintain the external field if the deformation of the interface remains negligibly small, requiring in turn sufficiently small applied thermal and electric gradients below critical values of hydrodynamic and electrostatic instabilities. We estimate the increase and the upper limit of the streaming potential as well as of the overall conversion efficiency as a function of the applied voltage and the film thickness scaled to the Debye length.

Dietzel, Mathias; Hardt, Steffen



Atmospheric pressure photoionization for enhanced compatibility in on-line micellar electrokinetic chromatography-mass spectrometry.  


Atmospheric pressure photoionization (APPI) is presented as a novel means for the combination of micellar electrokinetic chromatography (MEKC) and mass spectrometry (MS). The on-line coupling is achieved using an adapted sheath flow interface installed on an orthogonal APPI source. Acetone or toluene is added as dopant to the sheath liquid to enhance analyte photoionization. It is demonstrated that with APPI signal suppression and interferences by the surfactant sodium dodecyl sulfate (SDS) and nonvolatile buffers can be circumvented. This implies that MEKC conditions can be selected independently from MS detection. Moreover, it is shown that both polar and apolar compounds can be photoionized, thereby also facilitating the analysis of compounds that are not amenable to electrospray ionization. Consequently, the MEKC-APPI-MS system can provide effective separation and detection of compounds of diverse character in one run using background electrolytes containing up to 50 mM SDS. Concentration limits of detection derived from extracted-ion traces (full scan mode) of test compounds were approximately 1 microg/mL, and the detection sensitivity remained unaffected during 1 day of continuous use. Overall, the system features are very favorable for applications such as drug impurity profiling as is illustrated by the analysis of mebeverine and related compounds (both charged and neutral) at the 0.25% (w/w) level. PMID:16097769

Mol, Roelof; de Jong, Gerhardus J; Somsen, Govert W



Chiral micellar electrokinetic chromatography (CMEKC)-atmospheric pressure photoionization of benzoin derivatives using mixed molecular micelles  

PubMed Central

In the present work we report, for the first time, the successful on-line coupling of chiral micellar electrokinetic chromatography (CMEKC) to atmospheric pressure photo-ionization mass spectrometry (APPI-MS). Four structurally similar neutral test solutes (e.g., benzoin derivatives) were successfully ionized by APPI-MS. The mass spectra in the positive ion mode showed that the protonated molecular ions of benzoins are not the most abundant fragment ions. Simultaneous enantioseparation by CMEKC and on-line APPI-MS detection of four photoinitiators: hydrobenzoin (HBNZ), benzoin (BNZ), benzoin methyl ether (BME), benzoin ethyl ether (BEE), were achieved using an optimized molar ratio of mixed molecular micelle of two polymeric chiral surfactants (polysodium N-undecenoxy carbonyl-L-leucinate and polysodium N-undecenoyl-L,L-leucylvalinate). The CMEKC conditions, such as voltage, chiral polymeric surfactant concentration, buffer pH, and BGE concentration, were optimized using a multivariate central composite design (CCD). The sheath liquid composition (involving % v/v methanol, dopant concentration, electrolyte additive concentration, and flow rate) and spray chamber parameters (drying gas flow rate, drying gas temperature, and vaporizer temperature) were also optimized with CCD. Models built based on the CCD results and response surface method was used to analyze the interactions between factors and their effects on the responses. The final overall optimum conditions for CMEKC-APPI-MS were also predicted and found in agreement with the experimentally optimized parameters. PMID:21500208

He, Jun; Shamsi, Shahab A.



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


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

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



Separation and determination of nitrofuran antibiotics in turbot fish by microemulsion electrokinetic chromatography.  


A microemulsion electrokinetic chromatography (MEEKC) method has been developed for the determination of four nitrofuran antibiotics (furazolidone (FZD), furaltadone (FTD), nitrofurazone (NFZ) and nitrofurantoin (NFT)) in turbot fish. The effect of buffer the pH, the concentration of SDS and the concentrations of octane and butan-1-ol were studied systematically. With the optimized experimental conditions (octane, 0.82% (w/w); SDS, 3.48% (w/w); butan-1-ol, 6.48% (w/w); and 10 mM sodium tetraborate buffer (pH 9.70), with 30 kV as the applied voltage) all four analytes were baseline-separated within 8 min. Regression equations revealed a good linear relationship between the peak area of each compound and its concentration. The correlation coefficients of the four analytes were from 0.9945 to 0.9999. The relative standard deviations of the migration times and the peak areas were <1.84 and 5.16% (intra-day). The obtained recovery ranged between 97 and 104%. Moreover, the method was successfully validated and applied to the determination of nitrofuran antibiotics in contaminated fish. PMID:19609023

Jiang, Ting-Fu; Lv, Zhi-Hua; Wang, Yuan-Hong; Yue, Mei-E; Lian, Shuai



Simultaneous determination of eleven preservatives in cosmetics by micellar electrokinetic chromatography.  


A new method for the simultaneous quantitation of 11 preservatives-imidazolidinyl urea, benzyl alcohol, dehydroacetic acid, sorbic acid, phenoxyethanol, benzoic acid, salicylic acid, and four parabens (methyl, ethyl, propyl, and butyl)-in cosmetics by micellar electrokinetic capillary chromatography was established and validated. The separation was performed using an uncoated fused-silica capillary (50 pm id x 60.2 cm, effective length 50 cm) with a running buffer consisting of 15 mmol/L sodium tetraborate, 60 mmol/L boric acid, and 100 mmol/L sodium dodecyl sulfate. A 1:10 dilution of the running buffer was used as the sample buffer to extract the cosmetic samples. The key factors, such as the concentration and pH of the running and sample buffers, which influence quantitative analysis of the above 11 preservatives in cosmetic samples, were investigated in detail. The linear ranges of the calibration curves for imidazolidinyl urea and the other 10 preservatives were 50-1000 and 10-200 mg/L, respectively. The correlation coefficients of the standard curves were all higher than 0.999. The recoveries at the concentrations studied ranged from 93.0 to 102.7%. RSDs were all less than 5%. The new method with simple sample pretreatment met the needs for routine analysis of the 11 preservatives in cosmetics. PMID:22970574

Wang, Ping; Ding, Xiaojing; Li, Yun; Yang, Yuanyuan



The effects of functional magnetic nanotubes with incorporated nerve growth factor in neuronal differentiation of PC12 cells  

NASA Astrophysics Data System (ADS)

In this in vitro study the efficiency of magnetic nanotubes to bind with nerve growth factor (NGF) and the ability of NGF-incorporated magnetic nanotubes to release the bound NGF are investigated using rat pheochromocytoma cells (PC12 cells). It is found that functional magnetic nanotubes with NGF incorporation enabled the differentiation of PC12 cells into neurons exhibiting growth cones and neurite outgrowth. Microscope observations show that filopodia extending from neuron growth cones were in close proximity to the NGF-incorporated magnetic nanotubes, at times appearing to extend towards or into them. These results show that magnetic nanotubes can be used as a delivery vehicle for NGF and thus may be exploited in attempts to treat neurodegenerative disorders such as Parkinson's disease with neurotrophins. Further neurite outgrowth can be controlled by manipulating magnetic nanotubes with external magnetic fields, thus helping in directed regeneration.

Xie, Jining; Chen, Linfeng; Varadan, Vijay K.; Yancey, Justin; Srivatsan, Malathi



Effect of Ca incorporation on the dielectric nonlinear behavior of (Ba, Ca)TiO3 multi layer ceramic capacitors  

NASA Astrophysics Data System (ADS)

The difference in the dielectric nonlinearity was investigated by contrasting BaTiO3 and (Ba0.925Ca0.075)TiO3 multilayer ceramic capacitors utilizing the first order reversal curve (FORC) distribution based on the Preisach model. Ca incorporation caused a decrease of the dielectric constants in the low field but little differences in the high field region resulting in a steep ac field dependence, which became more significant with the decrease of temperature. Such behavior can be correlated with a decrease of the reversible and an increase of the irreversible FORC distribution near origin by Ca incorporation. These results suggest that Ca incorporation, which is known to cause the asymmetric off-center displacement at Ba-site, has the role of weakly pinning centers that increase the portion of irreversible domain walls that are immobile at low field but can contribute to polarization beyond a threshold field.

Yoon, Seok-Hyun; Park, Yunjung; Kim, Chang-Hoon; Kim, Doo-Young



Soft particle analysis of electrokinetics of biological cells and their model systems  

NASA Astrophysics Data System (ADS)

In this article, we review the applications of a novel theory (Ohshima 2009 Sci. Technol. Adv. Mater. 10 063001) to the analysis of electrokinetic data for various soft particles, that is, particles covered with an ion-permeable surface layer of polyelectrolytes. Soft particles discussed in this review include various biological cells and hydrogel-coated particles as a model of biological cells. Cellular transformations increase the concentration of sialic acid of glycoproteins and are associated with blocked biosynthesis of glycolipids and aberrant expression of the developmentally programmed biosynthetic pathway. The change in shape or biological function of cells may affect their surface properties and can be detected by electrokinetic measurements. The experimental results were analyzed with Ohshima's electrokinetic formula for soft particles and soft surfaces. As a model system, hydrogel surfaces that mimic biological surfaces were also prepared and their surface properties were studied.

Makino, Kimiko; Ohshima, Hiroyuki



Electrokinetic properties of soil minerals and soils modified with polyelectrolytes  

NASA Astrophysics Data System (ADS)

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.

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



Qualitative analysis of mycotoxins using micellar electrokinetic capillary chromatography  

SciTech Connect

Naturally occurring mycotoxins are separated using micellar electrokinetic capillary chromatography. Trends in the retention of these toxins, resulting from changes in mobile-phase composition and pH, are reported and presented as a means of alleviating coelution problems. Two sets of mobile-phase conditions are determined that provide unique separation selectivity. The facile manner by which mobile-phase conditions can be altered, without changes in instrumental configuration, allowed the acquisition of two distinctive, fully resolved chromatograms of 10 mycotoxins in a period of approximately 45 min. By adjusting retention times, using indigenous or added components in mycotoxin samples as normalization standards, it is possible to obtain coefficients of variation in retention time that average less than 1%. The qualitative capabilities of this methodology are evaluated by separating randomly generated mycotoxin-interferent mixtures. In this study, the utilization of normalized retention times applied to separations obtained with two sets of mobile-phase conditions permitted the identification of all the mycotoxins in five unknown samples without any misidentifications. 24 refs., 3 figs., 2 tabs.

Holland, R.D.; Sepaniak, M.J. (Univ. of Tennessee, Knoxville (United States))



Separation of some chiral flavanones by micellar electrokinetic chromatography.  


Micellar electrokinetic chromatography (MEKC) was applied for enantioseparation of selected flavanones, including naringin, hesperidin, neohesperidin, naringenin, hesperetin, pinostrobin, isosakuranetin, eriodictyol, and homoeriodictyol. gamma-Cyclodextrin (gamma-CD) and sodium cholate (SCh) were used as chiral modifiers inducing enantioselectivity to the background electrolyte. From among many investigated selectors only these two appeared to possess the best enantioselective properties in respect to studied flavanones. The mechanisms of their action are a little different; SCh used above critical micelle point concentration forms chiral micelles itself while gamma-CD is deprived of this property and requires addition of surfactants as, e.g., sodium dodecyl sulfate. It was found that SCh enables separation of flavanone glycosides diastereomers while separation of enantiomers of flavanone aglycones may be achieved with gamma-CD. Consideration of structural relation led to the suggestion that interaction of sugar moiety of glycosides with SCh micelles give rise to chiral recognition. MEKC appeared to be a suitable and efficient analytical tool to follow enantiomeric composition of flavanones. PMID:12900864

Asztemborska, Monika; Mi?kiewicz, Magdalena; Sybilska, Danuta



Multiple electrokinetic actuators for feedback control of colloidal crystal size.  


We report a feedback control method to precisely target the number of colloidal particles in quasi-2D ensembles and their subsequent assembly into crystals in a quadrupole electrode. Our approach relies on tracking the number of particles within a quadrupole electrode, which is used in a real-time feedback control algorithm to dynamically actuate competing electrokinetic transport mechanisms. Particles are removed from the quadrupole using DC-field mediated electrophoretic-electroosmotic transport, while high-frequency AC-field mediated dielectrophoretic transport is used to concentrate and assemble colloidal crystals. Our results show successful control of the size of crystals containing 20 to 250 colloidal particles with less than 10% error. Assembled crystals are characterized by their radius of gyration, crystallinity, and number of edge particles, and demonstrate the expected size-dependent properties. Our findings demonstrate successful ensemble feedback control of the assembly of different sized colloidal crystals using multiple actuators, which has broad implications for control over nano- and micro- scale assembly processes involving colloidal components. PMID:22864637

Juárez, Jaime J; Mathai, Pramod P; Liddle, J Alexander; Bevan, Michael A



Micellar electrokinetic chromatographic determination of triazine herbicides in water samples.  


Dispersive liquid-liquid microextraction combined with online sweeping preconcentration in micellar electrokinetic chromatography was developed for the simultaneous determination of five triazine herbicides (atrazine, simazine, propazine, prometon and simetryn) in water samples. Several experimental parameters affecting the extraction efficiencies such as the type and volume of both the extraction and dispersive solvents, the addition of salt to sample solution, the extraction time and the pH of the sample solution were investigated. Under optimum conditions, the linearity of the method was good in the range from 0.33 to 20 ng mL(-1) for simazine, propazine, atrazine and simetryn, and from 0.17 to 20 ng mL(-1) for prometon, respectively. The sensitivity enrichment factors were in the range from 1750 to 2100, depending on the compound. The limit of detection (S/N = 3) ranged from 0.05 to 0.10 ng mL(-1). The developed method was successfully applied to the analysis of the five triazines in river, ground and well waters. PMID:23978771

Li, Zhi; Zhang, Shuaihua; Yin, Xiaofang; Wang, Chun; Wang, Zhi



Micellar electrokinetic chromatography in zero-electroosmotic flow environment.  


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

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



AC electrokinetic manipulation of selenium nanoparticles for potential nanosensor applications  

SciTech Connect

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.

Mahmoodi, Seyed Reza [School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Bayati, Marzieh, E-mail: [School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Hosseinirad, Somayeh [School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Foroumadi, Alireza [Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Gilani, Kambiz [Department of Pharmaceutics, School of Pharmacy, Tehran University of Medical Science, Tehran (Iran, Islamic Republic of); Rezayat, Seyed Mahdi [School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)



An approximation of herd effect due to vaccinating children against seasonal influenza – a potential solution to the incorporation of indirect effects into static models  

PubMed Central

Background Indirect herd effect from vaccination of children offers potential for improving the effectiveness of influenza prevention in the remaining unvaccinated population. Static models used in cost-effectiveness analyses cannot dynamically capture herd effects. The objective of this study was to develop a methodology to allow herd effect associated with vaccinating children against seasonal influenza to be incorporated into static models evaluating the cost-effectiveness of influenza vaccination. Methods Two previously published linear equations for approximation of herd effects in general were compared with the results of a structured literature review undertaken using PubMed searches to identify data on herd effects specific to influenza vaccination. A linear function was fitted to point estimates from the literature using the sum of squared residuals. Results The literature review identified 21 publications on 20 studies for inclusion. Six studies provided data on a mathematical relationship between effective vaccine coverage in subgroups and reduction of influenza infection in a larger unvaccinated population. These supported a linear relationship when effective vaccine coverage in a subgroup population was between 20% and 80%. Three studies evaluating herd effect at a community level, specifically induced by vaccinating children, provided point estimates for fitting linear equations. The fitted linear equation for herd protection in the target population for vaccination (children) was slightly less conservative than a previously published equation for herd effects in general. The fitted linear equation for herd protection in the non-target population was considerably less conservative than the previously published equation. Conclusions This method of approximating herd effect requires simple adjustments to the annual baseline risk of influenza in static models: (1) for the age group targeted by the childhood vaccination strategy (i.e. children); and (2) for other age groups not targeted (e.g. adults and/or elderly). Two approximations provide a linear relationship between effective coverage and reduction in the risk of infection. The first is a conservative approximation, recommended as a base-case for cost-effectiveness evaluations. The second, fitted to data extracted from a structured literature review, provides a less conservative estimate of herd effect, recommended for sensitivity analyses. PMID:23339290



Graphoanalytical study on the economic effect of incorporating hydrocracking of the distillate feedstock in oil refineries of the fuel profile  

Microsoft Academic Search

1.To determine the possible range of application of the hydrocracking process in the oil refining industry, we have worked out a graphical method which makes it possible to determine a plant scheme incorporating catalytic cracking or hydrocracking units for the treatment of vacuum gas-oil and warranting a given total yield of light products and a given ratio between the yields

L. I. Erkina; Yu. I. Chernyi



Incorporation of fatty acids by concanavalin A-stimulated lymphocytes and the effect on fatty acid composition and membrane fluidity.  

PubMed Central

The fatty acid compositions of the neutral lipid and phospholipid fractions of rat lymph node lymphocytes were characterized. Stimulation of rat lymphocytes with the T-cell mitogen concanavalin A resulted in significant changes in the fatty acid composition of both neutral lipids and phospholipids (a decrease in the proportions of stearic, linoleic and arachidonic acids and an increase in the proportion of oleic acid). Membrane fluidity was measured using nitroxide spin-label e.s.r., and increased during culture with concanavalin A. Culturing the lymphocytes in the absence of mitogen did not affect fatty acid composition or membrane fluidity. The uptake and fate of palmitic, oleic, linoleic and arachidonic acids were studied in detail; there was a time-dependent incorporation of each fatty acid into all lipid classes but each fatty acid had a characteristic fate. Palmitic and arachidonic acids were incorporated principally into phospholipids whereas oleic and linoleic acids were incorporated in similar proportions into phospholipids and triacylglycerols. Oleic acid was incorporated mainly into phosphatidylcholine, palmitic and linoleic acids were incorporated equally into phosphatidylcholine and phosphatidylethanolamine, and arachidonic acid was incorporated mainly into phosphatidylethanolamine. Supplementation of the culture medium with particular fatty acids (myristic, palmitic, stearic, oleic, linoleic, alpha-linolenic, arachidonic, eicosapentaenoic or docosahexaenoic acid) led to enrichment of that fatty acid in both neutral lipids and phospholipids. This generated lymphocytes with phospholipids differing in saturated/unsaturated fatty acid ratio, degree of polyunsaturation, index of unsaturation and n - 6/n - 3 ratio. This method allowed the introduction into lymphocyte phospholipids of fatty acids not normally present (e.g. alpha-linolenic) or usually present in low proportions (eicosapentaenoic and docosahexaenoic). These three n - 3 polyunsaturated fatty acids replaced arachidonic acid in lymphocyte phospholipids. Fatty acid incorporation led to an alteration in lymphocyte membrane fluidity: palmitic and stearic acids decreased fluidity whereas the unsaturated fatty acids increased fluidity. It is proposed that the changes in lymphocyte phospholipid fatty acid composition and membrane fluidity brought about by culture in the presence of polyunsaturated fatty acids are responsible for the inhibition of lymphocyte functions caused by these fatty acids. PMID:8002957

Calder, P C; Yaqoob, P; Harvey, D J; Watts, A; Newsholme, E A



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

NASA Astrophysics Data System (ADS)

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.

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



[Effect of actinomycin D and sibiromycin on 3H-thymidine incorporation into the early developmental stages of Nereis virens Sars].  


The Nereis virens embryos at the stages of 2, 8, 16 and 32 blastomeres end of cleavage and beginning of rotation were placed in the actinomycin D or sibiromycin solutions and the effect of antibiotics on 3H-thymidine incorporation during cleavage, at the beginning of rotation and in trochophore was determined by means of autoradiography after careful washing the embryos off. Under the effect of actinomycin D the intensity of 3H-thymidine incorporation during cleavage decreased insignificantly, at the gastrula stage somewhat exceeded that in the control, and at the stages of trochophore formation decreased twice. At the later stages it approached the normal level. In the experiments with sibiromycin which proved to have more distinct inhibitory effect, the stage of trochophore formation was also found to be the most sensitive to the antibiotic. PMID:578569

Donua, A K; Fedorova, Zh E



Effects of cholesterol incorporation on the physicochemical, colloidal, and biological characteristics of pH-sensitive AB? miktoarm polymer-based polymersomes.  


In our previous study, a histidine-based AB2 miktoarm polymer, methoxy poly(ethylene glycol)-b-poly(l-histidine)2 (mPEG-b-(PolyHis)2), was designed to construct pH-sensitive polymersomes that transform in acidic pH; the polymer self-assembles into a structure that mimics phospholipids. In this study, the polymersomes further imitated liposomes due to the incorporation of cholesterol (CL). The hydrodynamic radii of the polymersomes increased with increasing CLwt% (e.g., 70 nm for 0 wt% vs. 91 nm for 1 wt%), resulting in an increased capacity for encapsulating hydrophilic drugs (e.g., 0.92 ?L/mg for 0 wt% vs. 1.42 ?L/mg for 1 wt%). The CL incorporation enhanced the colloidal stability of the polymersomes in the presence of serum protein and retarded their payload release. However, CL-incorporating polymersomes still demonstrated accelerated release of a hydrophilic dye (e.g., 5(6)-carboxyfluorescein (CF)) below pH 6.8 without losing their desirable pH sensitivity. CF-loaded CL-incorporating polymersomes showed better cellular internalization than the hydrophilic CF, whereas doxorubicin (DOX)-loaded CL-incorporating polymersomes presented similar or somewhat lower anti-tumor effects than free hydrophobic DOX. The findings suggest that CL-incorporating mPEG-b-(PolyHis)2-based polymersomes may have potential for intracellular drug delivery of chemical drugs due to their improved colloidal stability, lower drug loss during circulation, acidic pH-induced drug release, and endosomal disruption. PMID:24463148

Yin, Haiqing; Kang, Han Chang; Huh, Kang Moo; Bae, You Han



Removal of contaminants from fine grained soils using electrokinetic (EK) flushing. Final report, September 30, 1987--June 30, 1993  

SciTech Connect

Recently, attention has focused on developing cost effective techniques to remove inorganic contaminants from soils in-situ. For most in-situ techniques hydraulic pressure is used to disperse the chemical additives and collect the contaminated groundwater. In-situ treatment technologies have had success at sites containing sandy soils but have not shown much promise for soils with large amounts of clay and silt. This is due primarily to difficulty in transporting groundwater, contaminants, and chemical additives through the subsurface. Unfortunately, soils high in clay and silt are known to sequester large quantities of inorganic and organic contaminants. Thus, soils having low hydraulic conductivity`s are generally efficient in sequestering pollutants but are resistant to standard in-situ remediation techniques because of the difficulty in transporting groundwater and contaminants. A candidate technology for the in-situ remediation of low permeability soils is electrokinetic (EK) soil flushing. In EK soil flushing, groundwater and contaminants are transported under an a plied voltage. The transport of groundwater electroosmotically does not depend directly on the soil`s hydraulic conductivity. Thus, soils that would otherwise require excavation and treatment can be remediated in-situ if electrokinetics is used as the driving force for liquid and contaminant transport. This report details the results from work conducted on the use of EK soil flushing to remediate a fine grained soil contaminated with lead. The first portion of the experimental work entailed soil collection and characterization, soil adsorption and desorption of lead, and EK reactor construction and testing. The second phase of the research consisted of investigating the efficacy of using EK soil flushing on an actual soil using bench-scale EK reactors. For the second phase of the research the affect of initial conditions on the efficiency of EK soil flushing was studied.

Reed, B.E.; Berg, M.T.



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

NASA Astrophysics Data System (ADS)

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.

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



Application of iron electrode corrosion enhanced electrokinetic-Fenton oxidation to remediate diesel contaminated soils: A laboratory feasibility study  

NASA Astrophysics Data System (ADS)

SummaryDiesel soil contamination on gas stations or refinery plants is a worldwide environmental problem. The main objectives of this study were to (1) evaluate the efficiency of electrokinetic (EK) by using different electrode materials (graphite and iron rods) and electrolytes (tap water, 0.01 M NaCl, and 0.1 M NaCl) on the remediation of diesel contaminated soils, and (2) evaluate the feasibility of total petroleum hydrocarbon-diesel (TPH-D) reducing in soils via EK-Fenton oxidation enhanced by corroded iron electrode. The EK and EK-Fenton experiments were conducted in batch and sand box experiments, respectively. Batch experiments reveal that the most appropriate electrolyte was 0.1 M NaCl when iron electrode was used in the EK system. Sand box experiments indicate that the TPH-D concentration dropped from 10,000 to 300 mg kg -1 when amorphous iron/total iron (Fe o/Fe t) ratio increased from 0.1 to 0.33, with the addition of 8% of H 2O 2 and 0.1 M NaCl after 60 days of EK-Fenton operation. Electrokinetically enhanced oxidation with the presence of both H 2O 2 and Fe 3O 4 (iron electrode corrosion) resulted in higher TPH-D removal efficiency (97%) compared to the efficiencies observed from EK (55%) or Fenton oxidation (27%) alone. This demonstrates that EK-Fenton oxidation catalyzed by iron electrode corrosion is a valuable direction to efficiently and effectively remediate diesel contaminated soils.

Tsai, Tzai-Tang; Sah, Jygau; Kao, Chih-Ming



Study on Effect of Incorporation of Gelatin Fiber in Jute Fabrics-Reinforced Linear Low Density Polyethylene Composite  

Microsoft Academic Search

Jute fabrics (50%)-reinforced linear low density polyethylene (LLDPE) composite was prepared by compression molding and mechanical properties were studied. Gelatin fiber (2%–10%) was incorporated into the jute fabrics-based composites and their mechanical properties were investigated and compared with the control composite. It was found that with the increased of gelatin fiber content in the jute fabrics-based composites, the mechanical properties

Bapi Sarker; Ruhul A. Khan



The Shiraz model: a tool for incorporating anthropogenic effects and fish–habitat relationships in conservation planning  

Microsoft Academic Search

Current efforts to conserve Pacific salmon (Oncorhynchus spp.) rely on a variety of information sources, including empirical observations, expert opinion, and models. Here we outline a framework for incorporating detailed information on density-dependent population growth, habitat attributes, hatchery operations, and harvest management into conservation planning in a time-varying, spatially explicit manner. We rely on a multistage Beverton-Holt model to describe

Mark D. Scheuerell; Ray Hilborn; Mary H. Ruckelshaus; Krista K. Bartz; Kerry M. Lagueux; Andrew D. Haas; Kit Rawson



Effect of the mode of incorporation on the disintegrant properties of acid modified water and white yam starches  

PubMed Central

Acid modified starches obtained from two species of yam tubers namely white yam – Dioscorearotundata L. and water yam – D. alata L. DIAL2 have been investigated as intra- and extra-granular disintegrants in paracetamol tablet formulations. The native starches were modified by acid hydrolysis and employed as disintegrant at concentrations of 5 and 10% w/w and their disintegrant properties compared with those of corn starch BP. The tensile strength and drug release properties of the tablets, assessed using the disintegration and dissolution (t50 and t80 – time required for 50% and 80% of paracetamol to be released) times, were evaluated. The results showed that the tensile strength and the disintegration and dissolution times of the tablets decreased with increase in the concentration of the starch disintegrants. The acid modified yam starches showed better disintegrant efficiency than corn starch in the tablet formulations. Acid modification appeared to improve the disintegrant efficiency of the yam starches. Furthermore, tablets containing starches incorporated extragranularly showed faster disintegration but lower tensile strength than those containing starches incorporated intragranularly. This emphasizes the importance of the mode of incorporation of starch disintegrant. PMID:23960789

Odeku, Oluwatoyin A.; Akinwande, Babatunde L.



Effect of titanium incorporation on the structural, mechanical and biocompatible properties of DLC thin films prepared by reactive-biased target ion beam deposition method  

NASA Astrophysics Data System (ADS)

Amorphous diamond like carbon (DLC) and titanium incorporated diamond like carbon (Ti-DLC) thin films were deposited by using reactive-biased target ion beam deposition method. The effects of Ti incorporation and target bias voltage on the microstructure and mechanical properties of the as-deposited films were investigated by means of X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy and nano-indentation. It was found that the Ti content in Ti-DLC films gets increased with increasing target bias voltage. At about 4.2 at.% of Ti, uniform sized well dispersed nanocrystals were seen in the DLC matrix. Using FFT analysis, a facility available in the TEM, it was found that the nanocrystals are in cubic TiC phase. Though at the core, the incorporated Ti atoms react with carbon to form cubic TiC; most of the surface exposed Ti atoms were found to react with the atmospheric oxygen to form weakly bonded Ti-O. The presence of TiC nanocrystals greatly modified the sp 3/sp 2 hybridized bonding ratio and is reflected in mechanical hardness of Ti-DLC films. These films were then tested for their biocompatibility by an invitro cell culturing test. Morphological observation and the cell proliferation test have demonstrated that the human osteoblast cells well attach and proliferate on the surface of Ti incorporated DLC films, suggesting possible applications in bone related implant coatings.

Bharathy, P. Vijai; Nataraj, D.; Chu, Paul K.; Wang, Huaiyu; Yang, Q.; Kiran, M. S. R. N.; Silvestre-Albero, J.; Mangalaraj, D.



Effects of incorporated alkali metal ions on the chemical bonding states and optical properties in Sr2SiO4:Sm3+ phosphors  

NASA Astrophysics Data System (ADS)

The effects of incorporated alkali metal ions on the chemical bonding states and optical properties in samarium-doped strontium orthosilicate phosphors are studied. Sr2- x M x SiO4:Sm3+ (M = Li, Na, and K) phosphors are synthesized by using tje solid-state reaction method to vary the incorporated amount of the alkali metal ions. The structures, surface morphology, and chemical bonding states of the powders are analyzed. Optical properties for varying amounts of incorporated alkali metal ions are examined by measuring absorption, excitation, and emission spectra. A red-orange emission due to the transition of Sm3+ is observed in all samples, and powders with alkali metal ions incorporated exhibit enhanced emission intensities by a factor of 1.24 to 2.16 compared with that of z pure Sr2SiO4:Sm3+ powder with the same amount of Sm3+. We have shown that Sr2- x M x SiO4:Sm3+ ceramics exhibit a red-orange emission with enhanced intensity for operation with near ultra-violet excitation.

Ha, Myoung Gyu; Han, Kyoung-Rim; Kim, Ju Sung; Bae, Yu Ri; Kim, Jong Pil; Bae, Jong Seong; Hong, K. S.; Yang, Ho-Soon



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)

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.

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



Relative influences of solution composition and presence of intracrystalline proteins on magnesium incorporation in calcium carbonate minerals: Insight into vital effects  

NASA Astrophysics Data System (ADS)

Biogenic calcites may contain considerable magnesium concentrations, significantly higher than those observed in inorganic calcites. Control of ion concentrations in the calcifying space by transport systems and properties of the organic matrix of mineralization are probably involved in the incorporation of high magnesium quantities in biogenic calcites, but their relative effects have never been quantified. In vitro precipitation experiments performed at different Mg/Ca ratios in the solution and in the presence of soluble organic matrix macromolecules (SOM) extracted from sea urchin tests and spines showed that, at a constant temperature, magnesium incorporation in the precipitated minerals was mainly dependent on the Mg/Ca ratio of the solution. However, a significant increase in magnesium incorporation was observed in the presence of SOM compared with control experiments. Furthermore, this effect was more pronounced with SOM extracted from the test, which was richer in magnesium than the spines. According to SEM observations, amorphous calcium carbonate was precipitated at high Mg/Casolution. The observed predominant effect of Mg/Casolution, probably mediated in vivo by ion transport to and from the calcifying space, was suggested to induce and stabilize a transient magnesium-rich amorphous phase essential to the formation of high magnesium calcites. Aspartic acid rich proteins, shown to be more abundant in the test than in the spine matrix, further stabilize this amorphous phase. The involvement of the organic matrix in this process can explain the observation that sympatric organisms or even different skeletal elements of the same individual present different skeletal magnesium concentrations.

Hermans, Julie; André, Luc; Navez, Jacques; Pernet, Philippe; Dubois, Philippe



Determination of the herbicide metribuzin and its major conversion products in soil by micellar electrokinetic chromatography  

Microsoft Academic Search

In this paper, a multiresidue method for the analysis in soils of metribuzin (M) and its major conversion products, deaminometribuzin (DA), diketometribuzin (DK) and deaminodiketometribuzin (DADK) is developed. Considering the neutral and charged nature of the molecules, micellar electrokinetic chromatography (MEKC) is a very efficient method for the separation of these compounds, providing high efficiency and short analysis times. Different

José F. Huertas-Pérez; Monsalud del Olmo Iruela; Ana M. García-Campaña; Antonio González-Casado; Antonio Sánchez-Navarro



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

E-print Network

polarization can be induced even at moderate buffer concentrations because of local ion depletion (therefore induced EOF, concentration polarization, and limiting-current behavior. DOI: 10.1103/PhysRevLett.99Concentration Polarization and Nonlinear Electrokinetic Flow near a Nanofluidic Channel Sung Jae


Electrokinetic Hydrogen Generation from Liquid Water Microjets Andrew M. Duffin and Richard J. Saykally,*  

E-print Network

energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen electrode produces gaseous hydrogen molecules. The hydrogen production efficiency is currently very low (ca within the 21st century due to its high combustion efficiency, nonpolluting chemistry, and renewability

Cohen, Ronald C.


Electrolyte conditioning-enhanced electrokinetic remediation of arsenic-contaminated mine tailing  

Microsoft Academic Search

Feasibility of electrolyte conditioning with strong acidic or alkaline solution on electrokinetic remediation of arsenic-contaminated mine tailing was investigated in the laboratory. The mine tailing contained calcium oxide of more than 50%. At alkaline condition, arsenic was precipitated with calcium, and formed calcium arsenate which is very stable solid. Catholyte conditioning with strong acidic solution and anolyte conditioning with strong

Kitae Baek; Do-Hyung Kim; Sung-Woo Park; Byung-Gon Ryu; Tserennyam Bajargal; Jung-Seok Yang



Demonstrating Chemical and Analytical Concepts in the Undergraduate Laboratory Using Capillary Electrophoresis and Micellar Electrokinetic Chromatography  

Microsoft Academic Search

This paper describes instrumental analysis laboratory exercises that utilize capillary electrophoresis and micellar electrokinetic chromatography to demonstrate several analytical and chemical principles. Alkyl parabens (4-hydroxy alkyl benzoates), which are common ingredients in cosmetic formulations, are separated by capillary electrophoresis. The electrophoretic mobilities of the parabens can be explained on the basis of their relative size. 3-Hydroxy ethylbenzoate is also separated

Christopher P. Palmer



Pore network model of electrokinetic transport through charged porous media Amael Obliger,1, 2, 3  

E-print Network

for the numerical determination of the steady-state response of complex charged porous media to pressure, saltPore network model of electrokinetic transport through charged porous media Ama¨el Obliger,1, 2, 3 concentration and electric potential gradients. The macro- scopic fluxes of solvent, salt and charge

Paris-Sud XI, Université de



EPA Science Inventory

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


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

E-print Network

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

Miksik, Ivan


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

SciTech Connect

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.

Rozakeas, P.K.; Snow, R.J. [Royal Melbourne Inst. of Technology, Victoria (Australia)



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


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 (Vef) of polystyrene, graphite and aluminium-oxide particles in strong fields (100-400V/cm). This is in contrast to the electrophoresis in weak fields (5-20V/cm) in which adsorption of these polymers gives a drop in Vef 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

Barany, Sandor



Effect of a smartphone application incorporating personalized health-related imagery on adherence to antiretroviral therapy: a randomized clinical trial.  


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

Perera, Anna I; Thomas, Mark G; Moore, John O; Faasse, Kate; Petrie, Keith J



Modeling Ear-Canal Acoustics, Incorporating Visco-Thermal Effects and the Influence of the Middle Ear  

NASA Astrophysics Data System (ADS)

The ear canal, below about 6 kHz, is well described by a uniform cylinder (sound propagates predominantly as plane waves) with the middle ear being a non-rigid termination. A non-rigid termination can be viewed as altering, as a function of frequency, the acoustic length and radius of the cylinder. It is generally assumed that sound transmission in the ear canal over this frequency range is lossless. This paper presents a method for calculating the influence of visco-thermal losses and the middle ear on ear canal acoustics. The acoustic input impedance was derived from sound pressure measurements in the ear canal and then a nonlinear least-square-fit to the data with a one-dimensional model incorporating visco-thermal losses generated length, radius, and middle ear impedance parameters. It was found that a rigid wall assumption for visco-thermal calculations was insufficient to account for damping in the ear canal. The properties of the ear canal wall (not being a rigid, low-friction surface), incorporated into visco-thermal losses as a scaling factor, provided a better fit to the data. Viscous and thermal losses were both found to affect sound propagation in the ear canal, viscous losses being more significant, altering the acoustic input impedance of the ear primarily in the region of the standing wave frequency. The model data suggests that the middle ear influences ear canal acoustics up to about 3 kHz.

Gowdy, Lauren E.; Withnell, Robert H.



Evaluation of sintering effects on SiC incorporated UO2 kernels under Ar and Ar-4%H2 environments  

SciTech Connect

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.

Silva, Chinthaka M [ORNL] [ORNL; Lindemer, Terrence [Harbach Engineering and Solutions] [Harbach Engineering and Solutions; Hunt, Rodney Dale [ORNL] [ORNL; Collins, Jack Lee [ORNL] [ORNL; Terrani, Kurt A [ORNL] [ORNL; Snead, Lance Lewis [ORNL] [ORNL



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

SciTech Connect

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.

Qian, L. X.; Lai, P. T., E-mail: [Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road (Hong Kong); Tang, W. M. [Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)



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

PubMed Central

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



A neural network for incorporating the thermal effect on the magnetic hysteresis of the 3F3 material using the Jiles-Atherton model  

NASA Astrophysics Data System (ADS)

The present paper deals with the temperature dependent modeling approach for the generation of hysteresis loops of ferromagnetic materials. The physical model is developed to study the effect of temperature on the magnetic hysteresis loop using the Jiles-Atherton (J-A) model. The thermal effects were incorporated through temperature dependent hysteresis parameters of JA model. The temperature-dependent J-A model was validated by measurements made on the ferrite material. The results of proposed model were in good agreement with the measurements.

Nouicer, A.; Nouicer, E.; Feliachi, Mouloud



Effect of estradiol and progesterone on the rate of incorporation of radiolabeled arachidonate into phospholipids and triacylglycerols of the rat uterus  

SciTech Connect

To obtain information on the effect of estradiol(E) and progesterone(P) on the overall rate of the acylation and deacylation reactions with /sup 3/H-arachidonate (/sup 3/H-AA) in the rat uterus the authors investigated the effect of chronic treatment of ovariectomized rats with E-dipropionate (EDP) and with 2 mg P alone or with the combination of these steroids on the extent and the time course of the in vitro incorporation of /sup 3/H-AA into various phospholipids (PLs) and the triacylglycerol fraction (TG). The results demonstrate that physiologic doses of E leads to a rapid equilibrium of the deacylation-acylation cycle only in the case of phosphatidyl inositol (PI) whereas at high ( dose level it exerts the same effect on phosphatidyl choline (PC), phosphatidyl ethanolamine (PE) as well as on TG. P alone has no remarkable effects in the ovariectomized rat, but it decreases markedly the incorporation of /sup 3/H-AA into PI and TG in intact animals. Furthermore, P decreases the incorporation of /sup 3/H-AA into PI of the ovariectomized rat treated with EDP as well as attenuating the enhanced labeling rate of PC, PE and PI caused by higher doses. Time course studies provide evidence that all of these effects of P can be accounted for by its ability to decrease the rate of deacylation and, therefore, to prolong the time needed to attain equilibrium in the rates of acylation and deacylation reactions of the various lipids with arachidonate.

Toth, M.; Hertelendy, F.



Micellar electrokinetic chromatography method for the simultaneous determination of furanic compounds in honey and vegetable oils.  


A simple micellar electrokinetic chromatography (MEKC) method for the simultaneous determination of 2-furfural (2-F), 3-furfural (3-F), 5-methylfurfural (5-MF), 5-hydroxymethylfurfural (5-HMF), 2-furoic acid (2-FA) and 3-furoic acid (3-FA) in honey and vegetable oils is described. Parameters affecting the separation such as pH, buffer and surfactant concentrations, applied voltage, capillary temperature, injection time and capillary length were studied and optimized. The separation was carried out in normal polarity mode at 20 °C, 22 kV and using hydrodynamic injection (17 s). The separation was achieved in a bare fused-silica capillary (46 cm × 50 ?m i.d.) with a background electrolyte of 75 mM phosphoric acid (pH 7.3), containing 200 mM of sodium dodecyl sulphate (SDS). The detection wavelengths were at 200 nm (2-FA and 3-FA) and 280 nm (2-F, 3-F, 5-MF, 5-HMF). The furfurals were well separated in less than 20 min. The method was validated in terms of linearity, limit of detection and quantitation, precision and recoveries. Calibration curves of the six furfurals were well correlated (r(2)>0.991) within the range 1-25 ?g mL(-1). Relative standard deviations of intra- and inter-day migration times and corrected peak areas ?9.96% were achieved. The limit of detection (signal:noise, 3) was 0.33-0.70 ?g mL(-1) whereas the limit of quantitation (signal:noise, 10) was 1.00-2.12 ?g mL(-1). The method was applied to the determination of furanic compounds in honeys and vegetable oils (palm, walnut, grape seed and rapeseed). The effects of thermal treatment and gamma irradiation on the formation of the furanic compounds in honey were also investigated. PMID:22841043

Foo Wong, Yong; Makahleh, Ahmad; Al Azzam, Khaldun M; Yahaya, Noorfatimah; Saad, Bahruddin; Sulaiman, Siti Amrah



Oral consumption of electrokinetically modified water attenuates muscle damage and improves postexercise recovery.  


The purpose of this study was to assess the effects of consuming electrokinetically modified water (EMW) on attenuating muscle damage and improving functional recovery following a single bout of isokinetic resistance exercise. Subjects were randomly assigned to an EMW (n = 20) or a placebo control (n = 20) group. Subjects consumed EMW or placebo water daily for 23 days. On day 19 subjects completed an exercise protocol for the biceps brachii to induce muscle damage. The protocol consisted of three sets of 20 repetitions using concentric and eccentric contractions of the elbow flexors. Blood draw and clinical measurements were performed preexercise as well as 24, 48, and 96 h postexercise. Clinical measures included maximal isometric strength, muscle soreness, pain with elbow extension, relaxed elbow angle (RANG), and self-report arm disability. Plasma samples were analyzed to determine concentrations of creatine kinase (CK) and high-sensitivity C-reactive protein (hsCRP). Pain with elbow extension and self-report arm disability were significantly higher in the placebo group compared with the EMW group at 48 h (P < 0.01) and 96 h (P < 0.01) after exercise, while RANG was significantly higher in the EMW group compared with placebo at 48 h (P < 0.01) and 96 h (P < 0.01) after exercise. Similarly, plasma concentrations for hsCRP and CK were significantly lower in the EMW group compared with placebo at 48 h (P < 0.05) and 96 h (P < 0.01) after exercise. Oral consumption of EMW significantly reduced exercise-induced muscle damage and inflammation and improved functional recovery. PMID:23580602

Borsa, Paul A; Kaiser, Kelly L; Martin, Jeffrey S



Separation of paclitaxel and related taxanes by micellar electrokinetic capillary chromatography.  


Micellar electrokinetic capillary chromatography is used to separate paclitaxel (trade name Taxol, Bristol-Myers Squibb) and 14 related taxanes in 11.5 min. An aqueous acetonitrile (ACN) buffer containing sodium dodecyl sulfate (SDS) surfactant allows resolution of the 15 taxanes from each other and from the principal matrix ingredient in the injectable dosage form of the drug, Cremophor EL (polyethoxylated castor oil). Although the precise effect of high concentrations of ACN on micelle size and structure is not clear, the separation achieved is not possible in the absence of the organic modifier. The migration order is apparently the of decreasing aqueous-phase solubility, which is related to the presence of a side chain at the carbon 13-position, to the addition of a xylosyl group at the 7-position, and to the number of acetylated hydroxyl groups; it is also related to the increasing affinity of the taxane side chain for the micellar phase. The retention factors, k', increase linearly with SDS concentration above the critical micelle concentration. With increasing concentration of ACN, k' values for the taxanes without side chain decrease; for the most hydrophobic taxanes, k' increases up to 20% (v/v) ACN and then decreases sharply at higher concentrations; for the others, k' varies little up to 10% ACN, and then decreases rapidly with added ACN. Similar behavior was observed with methanol, but the break in k' occurred between 30% and 40% (v/v). Resolution was unacceptably poor if the samples dissolved in methanol were injected; samples dissolved in buffer containing SDS were well-behaved, probably because of stacking of the micelles during injection. Van't Hoff plots (in k' vs 1/T) were linear and allowed calculation of the delta H degree of transfer of taxane from aqueous to micelle phase. However, similar to the situation in HPLC, uncertainty in the micelle/aqueous phase ratio precludes reliable determination of the corresponding delta S degree. PMID:9511466

Shao, L K; Locke, D C



Separation and determination of acrylamide in potato chips by micellar electrokinetic capillary chromatography.  


A simple and rapid method using micellar electrokinetic capillary chromatography (MEKC) was developed for the separation and determination of acrylamide in potato chips at low levels for the first time. The experimental conditions for the separation and quantification of acrylamide were optimized at first. The optimized conditions were: 50mmol/L Na(2)B(4)O(7) and 40mmol/L SDS at pH 10.0, 12kV applied voltage, 76cm total length (67cm effective length) and 75mum i.d. capillary, 198nm wavelength, 15cm high 25s hydrodynamics sample injection, 20 degrees C air-cooling. The linear response of acrylamide concentration ranges from 0.5 to 100mug/mL with high correlation coefficient (r=0.9986, n=9). The LOD and LOQ were estimated to be 0.1 and 0.33mug/mL based on S/N=3 and 10. The precision values (expressed as R.S.D.) of intra- and inter-day were 0.86-4.35% and 2.61-9.65%, respectively. Recoveries spiked at levels 2, 20, 60mug/mL ranged between 90.86% and 99.6% with R.S.D. less than 6.5%. Finally, the developed method has been applied to the analysis of real samples and has achieved satisfactory results. All of these indicated that it was a reliable method for the quantification of acrylamide in potato chips. PMID:19071489

Zhou, Xun; Fan, Liu-Yin; Zhang, Wei; Cao, Cheng-Xi



Effects of dicyclohexylamine on polyamine biosynthesis and incorporation into turnip yellow mosaic virus in Chinese cabbage protoplasts infected in vitro  

SciTech Connect

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.

Balint, R.; Cohen, S.S.



What dental educators need to understand about emerging technologies to incorporate them effectively into the educational process.  


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

Stein, Corey D; Eisenberg, Elise S; O'Donnell, Jean A; Spallek, Heiko



Cosolvent-enhanced Desorption and Transport of Heavy Metals and Organic Contaminants in Soils during Electrokinetic Remediation  

Microsoft Academic Search

Numerous sites are contaminated with both heavy metals and polycyclic aromatic hydrocarbons (PAHs) and the technologies to\\u000a treat such mixed contaminants are very limited. Electrokinetic remediation has the potential to remediate mixed contaminants\\u000a in soils, including low permeability soils; however, the efficiency of this technology depends on the extracting solution\\u000a employed. Previous studies on electrokinetic remediation have focused on the

Kranti Maturi; Krishna R. Reddy



Effect of incorporating legume flour into semolina spaghetti on its cooking quality and glycaemic impact measured in vitro.  


Spaghetti is a favoured carbohydrate source because of its low glycaemic impact. The protein quality of semolina spaghetti is not ideal, however, and could be improved by including legume flour. We investigated whether incorporating legume flour in spaghetti, to improve its nutritional value, would affect its cooking quality and glycaemic impact. Four types of spaghetti containing 10% of either mung bean, soya bean, red lentil or chickpea flour were made and compared with a spaghetti control made only of durum semolina. Cooking quality was determined as the optimal cooking time (OCT), cooking loss (CL), dry matter (DM), swelling index, colour, hardness and adhesiveness. The spaghetti samples with legume flour were similar to one another and to the control in values of OCT, DM, swelling index, colour, CL, hardness and adhesiveness. Glycaemic impact of the samples was measured in vitro as release of rapidly available carbohydrate and slowly available carbohydrate during pancreatic digestion. The glycaemic index (GI) of the spaghetti samples was estimated by calculation, using data obtained for a reference food of known GI (shredded wheat horizontal line an extrusion-cooked wheat-only product). The shredded wheat underwent rapid parabolic digestion, and the near linear phase during which most of the starch was digested was completed between 20 and 60 min digestion. In contrast, the digestion of spaghetti was much slower and progressed almost linearly to completion. All spaghetti samples, moreover, were similarly susceptible to digestion, and compared with the wheat reference were all significantly lower in terms of relative glycaemic impact. We conclude that the incorporation of 10% legume flour in spaghetti to improve its nutritional value does not affect its cooking quality or increase its glycaemic impact. PMID:20113187

Chillo, Stefania; Monro, J A; Mishra, S; Henry, C J



Generating a Dipole Momentum Source with a Non-Uniform AC field: A New Long-Range Electro-kinetic Micro-Pump Design  

NASA Astrophysics Data System (ADS)

An AC electrokinetic funnel flow is generated by a planar micro-coil resister design capable of sustaining 3500V without Faradaic reactions. The final line of the serpentine coil exhibits a transverse electro-osmotic slip velocity exceeding 1 cm/sec. Due to side boundaries, a large back pressure is established in the slip direction to produce an intense vortex cylinder. As the coil design stipulates a vortex circulation that is longitudinally non-uniform, the longitudinal gradient in the back pressure drives a secondary flow to transform the vortex flow into a funnel flow. This funnel flow resembles a dipole momentum line source with large field-line penetration and can be used to effectively transport fluid at the microscale. Unlike all previous electrode-based AC electrokinetic micropump designs, fluid motion is not confined to the polarized electrode surface, which allows one to generate long-range pumping without having to employ large-scale electrode arrays that span the entire length of the microchannel.

Gordon, Jason; Gagnon, Zachary; Chang, Hsueh-Chia



A method incorporating 4DCT data for evaluating the dosimetric effects of respiratory motion in single-arc IMAT  

NASA Astrophysics Data System (ADS)

This study introduces a method incorporating 4DCT data to determine the impact of respiratory motion in single-arc intensity-modulated arc therapy (IMAT). Simulation was done by re-warping the static dose distribution of all phases of a 4DCT image set with a 3D deformation map to reference CT images at end-inspiration and end-expiration. To calculate the dose received during respiration under IMAT, the control points were interpolated and re-distributed into separate IMAT plans corresponding to each respiratory phase. This study also investigated the role that plan complexity may play in the dosimetric impact of the respiratory motion in the delivery of IMAT. The dosimetric impact of organ motion was evaluated by analyzing the degradation of D95, D50 and D05 of the CTV and PTV. From the results shown for the patients in this study who had maximum organ motion displacement ~15 mm, the dosimetric impact is rather small. Therefore, our preliminary results suggest that respiratory motion of less than 1.5 cm may be ignored for both moderately and highly modulated IMAT, irrespective of the number of fractions. Specifically, highly modulated plans only increased the degradation of D95 of the DVH curves for a single fraction by 2% in the CTV and 9% in the PTV compared to the expected value of the multi-fraction plan.

Kuo, H. C.; Mah, D.; Chuang, K. S.; Wu, A.; Hong, L.; Yaparpalvi, R.; Spierer, M.; Kalnicki, S.



Effects of silk fibroin fiber incorporation on mechanical properties, endothelial cell colonization and vascularization of PDLLA scaffolds  

PubMed Central

Attainment of functional vascularization of engineered constructs is one of the fundamental challenges of tissue engineering. However, the development of an extracellular matrix in most tissues, including bone, is dependent upon the establishment of a well developed vascular supply. In this study a poly-D,L-lactic acid (PDLLA) salt-leached sponge was modified by incorporation of silk fibroin fibers to create a multicomponent scaffold, in an effort to better support endothelial cell colonization and to promote in vivo vascularization. Scaffolds with and without silk fibroin fibers were compared for microstructure, mechanical properties, ability to maintain cell populations in vitro as well as to permit vascular ingrowth into acellular constructs in vivo. We demonstrated that adding silk fibroin fibers to a PDLLA salt-leached sponge enhanced scaffold properties and heightened its capacity to support endothelial cells in vitro and to promote vascularization in vivo. Therefore refinement of scaffold properties by inclusion of materials with beneficial attributes may promote and shape cellular responses. PMID:23522374

Stoppato, M.; Stevens, H. Y.; Carletti, E.; Migliaresi, C.; Motta, A.; Guldberg, R. E.



The effects of atmospheric [CO2] on carbon isotope fractionation and magnesium incorporation into biogenic marine calcite  

NASA Technical Reports Server (NTRS)

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.

Vieira, Veronica



The effects of phorate and some of its metabolites incorporated in an artificial diet on liquid uptake by Aphis fabae scop.  


[14C]Phorate and some of its metabolites were incorporated in an artificial diet and their effects on liquid uptake by Aphis fabae were studied. At sublethal and very low toxicity levels of phorate there was a tendency for a reduction in feeding with increasing concentrations. [14C]Phorate sulphone, [14C]phorate sulphoxide and [14C]phoratoxon sulphoxide at high concentrations gave very low mortality figures, but a significant drop in liquid uptake occurred with increasing concentrations. The results demonstrate that the presence of the insecticide rendered the diet less acceptable to the aphids which exhibited a wandering behaviour that might promote transmission of virus diseases. PMID:6836592

Ho, S H



Effects of Grid DC Bias on Incorporation of Si Clusters into Amorphous Silicon Thin Films in Multi-Hollow Discharge Plasma CVD  

NASA Astrophysics Data System (ADS)

Si clusters formed in silane discharge plasmas are mainly responsible for light induced degradation of hydrogenated amorphous Si (a-Si:H) thin films deposited by the plasmas. Here we have investigated effects of grid DC bias on incorporation amount of Si clusters into a-Si:H films in multi-hollow discharge plasma CVD reactor using quartz crystal microbalances, by which volume fraction of Si clusters in deposited films is quantitatively measured. When the grid potential is lower than plasma potential, the negatively charged clusters are repelled away from the grid by electrostatic force, resulting in lower volume fraction.

Toko, Susumu; Kim, Yeonwon; Hashimoto, Yuji; Kanemitu, Yoshinori; Seo, Hyunwoong; Uchida, Giichiro; Kamataki, Kunihiro; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu


Preparation of nano-Cu2O/TiO2 photocatalyst from waste printed circuit boards by electrokinetic process.  


It is difficult for separation and reutilization of Cu in waste printed circuit boards (PCBs) due to the heterogeneous mix of polymer materials, multiple kinds of metals and glass fiber. In this study, waste PCBs were pretreated by supercritical water oxidation (SCWO), then introduced into an electrokinetic (EK) system with nano-TiO(2) suspension as catholyte. In the EK process, Cu could be leached and reduced separately from the complicated multi-metal system in cathode compartment, and Cu(2)O could be formed in nano-size on TiO(2) surface. The properties of the composite catalysts Cu(2)O/TiO(2) were examined and their photocatalytic efficiencies were determined for methylene blue (MB) degradation. The results indicated that the catalytic effect increased with increasing EK preparation time but decreased afterwards. The most effective catalyst (4.53 wt.% Cu(2)O/TiO(2)), whose degradation ability was found to be much higher in comparison with commercial P25, was prepared by 6h EK treatment. It was found that the loading of Cu(2)O on TiO(2) surface could greatly enhance the photocatalytic effect of the catalyst. It is believed that the EK technology is effective and green for direct preparation of high value-added Cu nanocomposite materials from waste PCBs or other Cu-rich wastes. PMID:19740601

Xiu, Fu-Rong; Zhang, Fu-Shen



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

NASA Astrophysics Data System (ADS)

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.

Chun, Myung-Suk



Ripple structure-generated hybrid electrokinetics for on-chip mixing and separating of functionalized beads.  


We present an electrokinetics-based microfluidic platform that is capable of on-chip manipulating, mixing, and separating microparticles through adjusting the interrelated magnitudes of dielectrophoresis and AC electroosmosis. Hybrid electrokinetic phenomenon is generated from an electric field-induced micro-ripple structure made of ultraviolet-curable glue. Size-dependent particle separation and selective removal over the ripple structure is demonstrated successfully. Varying the waveform from sine-wave to square-wave allows generating a fluid convection at specific positions to mix the antibody-functionalized beads and antigen. Potential application in the bead-based immunoassay was also demonstrated for immuno-reaction and subsequently separating the bead-bead aggregate and non-binding beads on-chip. PMID:25610512

Cheng, I-Fang; Chiang, Sheng-Chuan; Chung, Cheng-Che; Yeh, Trai-Ming; Chang, Hsien-Chang



Research and experimental testing of a new kind electrokinetic logging tool  

NASA Astrophysics Data System (ADS)

We designed a new downhole electrokinetic logging tool based on numerical simulations and petrophysical experiments. Acoustic and electric receivers cannot be arranged at the same depth, and the proposed composite electrokinetic logging tool offers a solution to this problem. The sound field characteristics of the detectors were tested in a water tank in the laboratory. Then, we calculated the sound pressure of the radiated acoustic field and the transmitting voltage response of the transmitting transducers;