Identification of a molecular pH sensor in coral.

PubMed

Barott, Katie L; Barron, Megan E; Tresguerres, Martin

2017-11-15

Maintaining stable intracellular pH (pHi) is essential for homeostasis, and requires the ability to both sense pH changes that may result from internal and external sources, and to regulate downstream compensatory pH pathways. Here we identified the cAMP-producing enzyme soluble adenylyl cyclase (sAC) as the first molecular pH sensor in corals. sAC protein was detected throughout coral tissues, including those involved in symbiosis and calcification. Application of a sAC-specific inhibitor caused significant and reversible pHi acidosis in isolated coral cells under both dark and light conditions, indicating sAC is essential for sensing and regulating pHi perturbations caused by respiration and photosynthesis. Furthermore, pHi regulation during external acidification was also dependent on sAC activity. Thus, sAC is a sensor and regulator of pH disturbances from both metabolic and external origin in corals. Since sAC is present in all coral cell types, and the cAMP pathway can regulate virtually every aspect of cell physiology through post-translational modifications of proteins, sAC is likely to trigger multiple homeostatic mechanisms in response to pH disturbances. This is also the first evidence that sAC modulates pHi in any non-mammalian animal. Since corals are basal metazoans, our results indicate this function is evolutionarily conserved across animals. © 2017 The Author(s).

Absorptive capacity as a guiding concept for effective public sector management and conservation of freshwater ecosystems.

PubMed

Murray, K; Roux, D J; Nel, J L; Driver, A; Freimund, W

2011-05-01

The ability of an organisation to recognise the value of new external information, acquire it, assimilate it, transform, and exploit it, namely its absorptive capacity (AC), has been much researched in the context of commercial organisations and even applied to national innovation. This paper considers four key AC-related concepts and their relevance to public sector organisations with mandates to manage and conserve freshwater ecosystems for the common good. The concepts are the importance of in-house prior related knowledge, the importance of informal knowledge transfer, the need for motivation and intensity of effort, and the importance of gatekeepers. These concepts are used to synthesise guidance for a way forward in respect of such freshwater management and conservation, using the imminent release of a specific scientific conservation planning and management tool in South Africa as a case study. The tool comprises a comprehensive series of maps that depict national freshwater ecosystem priority areas for South Africa. Insights for implementing agencies relate to maintaining an internal science, rather than research capacity; making unpublished and especially tacit knowledge available through informal knowledge transfer; not underestimating the importance of intensity of effort required to create AC, driven by focussed motivation; and the potential use of a gatekeeper at national level (external to the implementing organisations), possibly playing a more general 'bridging' role, and multiple internal (organisational) gatekeepers playing the more limited role of 'knowledge translators'. The role of AC as a unifying framework is also proposed.

External Beam Radiotherapy for Prostate Cancer Patients on Anticoagulation Therapy: How Significant is the Bleeding Toxicity?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choe, Kevin S.; Jani, Ashesh B.; Liauw, Stanley L., E-mail: sliauw@radonc.uchicago.ed

Purpose: To characterize the bleeding toxicity associated with external beam radiotherapy for prostate cancer patients receiving anticoagulation (AC) therapy. Methods and Materials: The study cohort consisted of 568 patients with adenocarcinoma of the prostate who were treated with definitive external beam radiotherapy. Of these men, 79 were receiving AC therapy with either warfarin or clopidogrel. All patients were treated with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy. Bleeding complications were recorded during treatment and subsequent follow-up visits. Results: With a median follow-up of 48 months, the 4-year actuarial risk of Grade 3 or worse bleeding toxicity was 15.5% for those receivingmore » AC therapy compared with 3.6% among those not receiving AC (p < .0001). On multivariate analysis, AC therapy was the only significant factor associated with Grade 3 or worse bleeding (p < .0001). For patients taking AC therapy, the crude rate of bleeding was 39.2%. Multivariate analysis within the AC group demonstrated that a higher radiotherapy dose (p = .0408), intensity-modulated radiotherapy (p = 0.0136), and previous transurethral resection of the prostate (p = .0001) were associated with Grade 2 or worse bleeding toxicity. Androgen deprivation therapy was protective against bleeding, with borderline significance (p = 0.0599). Dose-volume histogram analysis revealed that Grade 3 or worse bleeding was minimized if the percentage of the rectum receiving >=70 Gy was <10% or the rectum receiving >=50 Gy was <50%. Conclusion: Patients taking AC therapy have a substantial risk of bleeding toxicity from external beam radiotherapy. In this setting, dose escalation or intensity-modulated radiotherapy should be used judiciously. With adherence to strict dose-volume histogram criteria and minimizing hotspots, the risk of severe bleeding might be reduced.« less

Numerical and theoretical evaluations of AC losses for single and infinite numbers of superconductor strips with direct and alternating transport currents in external AC magnetic field

NASA Astrophysics Data System (ADS)

Kajikawa, K.; Funaki, K.; Shikimachi, K.; Hirano, N.; Nagaya, S.

2010-11-01

AC losses in a superconductor strip are numerically evaluated by means of a finite element method formulated with a current vector potential. The expressions of AC losses in an infinite slab that corresponds to a simple model of infinitely stacked strips are also derived theoretically. It is assumed that the voltage-current characteristics of the superconductors are represented by Bean's critical state model. The typical operation pattern of a Superconducting Magnetic Energy Storage (SMES) coil with direct and alternating transport currents in an external AC magnetic field is taken into account as the electromagnetic environment for both the single strip and the infinite slab. By using the obtained results of AC losses, the influences of the transport currents on the total losses are discussed quantitatively.

Control of effect on the nucleation rate for hen egg white lysozyme crystals under application of an external ac electric field.

PubMed

Koizumi, H; Uda, S; Fujiwara, K; Nozawa, J

2011-07-05

The effect of an external ac electric field on the nucleation rate of hen egg white lysozyme crystals increased with an increase in the concentration of the precipitant used, which enabled the design of an electric double layer (EDL) formed at the inner surface of the drop in the oil. This is attributed to the thickness of the EDL controlled by the ionic strength of the precipitant used. Control of the EDL formed at the interface between the two phases is important to establishing this novel technique for the crystallization of proteins under the application of an external ac electric field. © 2011 American Chemical Society

Using an Adoption–Biological Family Design to Examine Associations Between Maternal Trauma, Maternal Depressive Symptoms, and Child Internalizing and Externalizing Behaviors

PubMed Central

Grabow, Aleksandria Perez; Khurana, Atika; Natsuaki, Misaki N.; Neiderhiser, Jenae M.; Harold, Gordon T.; Shaw, Daniel S.; Ganiban, Jody M.; Reiss, David; Leve, Leslie D.

2017-01-01

Maternal trauma is a complex risk factor that has been linked to adverse child outcomes, yet the mechanisms underlying this association are not well understood. This study, which included adoptive and biological families, examined the heritable and environmental mechanisms by which maternal trauma and associated depressive symptoms are linked to child internalizing and externalizing behaviors. Path analyses were used to analyze data from 541 adoptive mother–adopted child (AM–AC) dyads and 126 biological mother–biological child (BM–BC) dyads; the two family types were linked through the same biological mother. Rearing mother’s trauma was associated with child internalizing and externalizing behaviors in AM–AC and BM–BC dyads, and this association was mediated by rearing mothers’ depressive symptoms, with the exception of biological child externalizing behavior, for which biological mother trauma had a direct influence only. Significant associations between maternal trauma and child behavior in dyads that share only environment (i.e., AM–AC dyads) suggest an environmental mechanism of influence for maternal trauma. Significant associations were also observed between maternal depressive symptoms and child internalizing and externalizing behavior in dyads that were only genetically related, with no shared environment (i.e., BM–AC dyads), suggesting a heritable pathway of influence via maternal depressive symptoms. PMID:29162177

Using an adoption-biological family design to examine associations between maternal trauma, maternal depressive symptoms, and child internalizing and externalizing behaviors.

PubMed

Grabow, Aleksandria Perez; Khurana, Atika; Natsuaki, Misaki N; Neiderhiser, Jenae M; Harold, Gordon T; Shaw, Daniel S; Ganiban, Jody M; Reiss, David; Leve, Leslie D

2017-12-01

Maternal trauma is a complex risk factor that has been linked to adverse child outcomes, yet the mechanisms underlying this association are not well understood. This study, which included adoptive and biological families, examined the heritable and environmental mechanisms by which maternal trauma and associated depressive symptoms are linked to child internalizing and externalizing behaviors. Path analyses were used to analyze data from 541 adoptive mother-adopted child (AM-AC) dyads and 126 biological mother-biological child (BM-BC) dyads; the two family types were linked through the same biological mother. Rearing mother's trauma was associated with child internalizing and externalizing behaviors in AM-AC and BM-BC dyads, and this association was mediated by rearing mothers' depressive symptoms, with the exception of biological child externalizing behavior, for which biological mother trauma had a direct influence only. Significant associations between maternal trauma and child behavior in dyads that share only environment (i.e., AM-AC dyads) suggest an environmental mechanism of influence for maternal trauma. Significant associations were also observed between maternal depressive symptoms and child internalizing and externalizing behavior in dyads that were only genetically related, with no shared environment (i.e., BM-AC dyads), suggesting a heritable pathway of influence via maternal depressive symptoms.

Development and Validation of a Reversed Phase HPLC Method for Determination of Anacardic Acids in Cashew (Anacardium occidentale) Nut Shell Liquid.

PubMed

Oiram Filho, Francisco; Alcântra, Daniel Barbosa; Rodrigues, Tigressa Helena Soares; Alexandre E Silva, Lorena Mara; de Oliveira Silva, Ebenezer; Zocolo, Guilherme Julião; de Brito, Edy Sousa

2018-04-01

Cashew nut shell liquid (CNSL) contains phenolic lipids with aliphatic chains that are of commercial interest. In this work, a chromatographic method was developed to monitor and quantify anacardic acids (AnAc) in CNSL. Samples containing AnAc were analyzed on a high-performance liquid chromatograph coupled to a diode array detector, equipped with a reversed phase C18 (150 × 4.6 mm × 5 μm) column using acetonitrile and water as the mobile phase both acidified with acetic acid to pH 3.0 in an isocratic mode (80:20:1). The chromatographic method showed adequate selectivity, as it could clearly separate the different AnAc. To validate this method, AnAc triene was used as an external standard at seven different concentrations varying from 50 to 1,000 μg mL-1. The Student's t-test and F-test were applied to ensure high confidence for the obtained data from the analytical calibration curve. The results were satisfactory with respect to intra-day (relative standard deviation (RSD) = 0.60%) and inter-day (RSD = 0.67%) precision, linearity (y = 2,670.8x - 26,949, r2 > 0.9998), system suitability for retention time (RSD = 1.02%), area under the curve (RSD = 0.24%), selectivity and limits of detection (19.8 μg mg-1) and quantification (60.2 μg mg-1). The developed chromatographic method was applied for the analysis of different CNSL samples, and it was deemed suitable for the quantification of AnAc.

ISOON + SOLIS: Merging the Data Products

NASA Astrophysics Data System (ADS)

Radick, R.; Dalrymple, N.; Mozer, J.; Wiborg, P.; Harvey, J.; Henney, C.; Neidig, D.

2005-05-01

The combination of AFRL's ISOON and NSO's SOLIS offers significantly greater capability than the individual instruments. We are working toward merging the SOLIS and ISOON data products in a single central facility. The ISOON system currently includes both an observation facility and a remote analysis center (AC). The AC is capable of receiving data from both the ISOON observation facility as well as external sources. It archives the data and displays corrected images and time-lapse animations. The AC has a large number of digital tools that can be applied to solar images to provide quantitative information quickly and easily. Because of its convenient tools and ready archival capability, the ISOON AC is a natural place to merge products from SOLIS and ISOON. We have completed a preliminary integration of the ISOON and SOLIS data products. Eventually, we intend to distribute viewing stations to various users and academic institutions, install the AC software tools at a number of user locations, and publish ISOON/SOLIS data products jointly on a common web page. In addition, SOLIS data products, separately, are and will continue to be fully available on the NSO,s Digital Library and SOLIS web pages, and via the Virtual Solar Observatory. This work is being supported by the National Science Foundation and the Air Force Office of Scientific Research.

Measurement of Shoulder Range of Motion in Patients with Adhesive Capsulitis Using a Kinect

PubMed Central

Chung, Sun Gun; Kim, Hee Chan; Kwak, Youngbin; Park, Hee-won; Kim, Keewon

2015-01-01

Range of motion (ROM) measurements are essential for the evaluation for and diagnosis of adhesive capsulitis of the shoulder (AC). However, taking these measurements using a goniometer is inconvenient and sometimes unreliable. The Kinect (Microsoft, Seattle, WA, USA) is gaining attention as a new motion detecting device that is nonintrusive and easy to implement. This study aimed to apply Kinect to measure shoulder ROM in AC; we evaluated its validity by calculating the agreement of the measurements obtained using Kinect with those obtained using goniometer and assessed its utility for the diagnosis of AC. Both shoulders of 15 healthy volunteers and affected shoulders of 12 patients with AC were included in the study. The passive and active ROM of each were measured with a goniometer for flexion, abduction, and external rotation. Their active shoulder motions for each direction were again captured using Kinect and the ROM values were calculated. The agreement between the two measurements was tested with the intraclass correlation coefficient (ICC). Diagnostic performance using the Kinect ROM was evaluated with Cohen’s kappa value. The cutoff values of the limited ROM were determined in the following ways: the same as passive ROM values, reflecting the mean difference, and based on receiver operating characteristic curves. The ICC for flexion/abduction/external rotation between goniometric passive ROM and the Kinect ROM were 0.906/0.942/0.911, while those between active ROMs and the Kinect ROMs were 0.864/0.932/0.925. Cohen’s kappa values were 0.88, 0.88, and 1.0 with the cutoff values in the order above. Measurements of the shoulder ROM using Kinect show excellent agreement with those taken using a goniometer. These results indicate that the Kinect can be used to measure shoulder ROM and to diagnose AC as an alternative to goniometer. PMID:26107943

Application of largest Lyapunov exponent analysis on the studies of dynamics under external forces

NASA Astrophysics Data System (ADS)

Odavić, Jovan; Mali, Petar; Tekić, Jasmina; Pantić, Milan; Pavkov-Hrvojević, Milica

2017-06-01

Dynamics of driven dissipative Frenkel-Kontorova model is examined by using largest Lyapunov exponent computational technique. Obtained results show that besides the usual way where behavior of the system in the presence of external forces is studied by analyzing its dynamical response function, the largest Lyapunov exponent analysis can represent a very convenient tool to examine system dynamics. In the dc driven systems, the critical depinning force for particular structure could be estimated by computing the largest Lyapunov exponent. In the dc+ac driven systems, if the substrate potential is the standard sinusoidal one, calculation of the largest Lyapunov exponent offers a more sensitive way to detect the presence of Shapiro steps. When the amplitude of the ac force is varied the behavior of the largest Lyapunov exponent in the pinned regime completely reflects the behavior of Shapiro steps and the critical depinning force, in particular, it represents the mirror image of the amplitude dependence of critical depinning force. This points out an advantage of this technique since by calculating the largest Lyapunov exponent in the pinned regime we can get an insight into the dynamics of the system when driving forces are applied. Additionally, the system is shown to be not chaotic even in the case of incommensurate structures and large amplitudes of external force, which is a consequence of overdampness of the model and the Middleton's no passing rule.

Magnetic characteristics and AC losses of DC type-II superconductors under oscillating magnetic fields

NASA Astrophysics Data System (ADS)

Robert, B. C.; Ruiz, H. S.

2018-07-01

Remarkable features on the magnetic moment of type-II superconducting (SC) wires of cylindrical shape, subjected to direct current conditions (DC) and transverse oscillating (AC) magnetic fields, are reported. We show how for relatively low amplitudes of the applied magnetic field, B a , the superconducting wire rapidly develops a saturation state, | {M}p| , characterizing the limits of magnetization loops that exhibit a Boolean-like behaviour. Regardless of the premagnetization state of the SC wire, we show how after two cycles of magnetic relaxation, boolean-like ±M p states can be measured during the entire period of time from which the external magnetic field B 0 ranges from 0 to ±B a , with the signs rule defined by the sign of the slope ΔB 0y (t). In addition, for the practical implementation of SC DC wires sharing the right of way with AC lines, we report that for relatively low values of magnetic field, {B}a≤slant {B}P/2, being B P the analytical value for the full penetration field in absence of transport current, I tr, the use of semi-analytical approaches for the calculation of AC losses leads to a significant underestimation of the actual contribution of the induction losses. This phenomena is particularly relevant at dimensionless fields {b}a< 1-{i}a2/3, being b a = B a /B P and, i a = I a /I c the amplitude of an AC or DC transport current, due to the local motion of flux front profiles being dominated by the occurrence of transport current. On the other hand, we have found that regardless of the nature of the transport current, either be DC or AC, when a transverse oscillating magnetic field greater than the classical limit b a = (1 - i a ) is applied to the SC wire, the difference between the obtained AC losses in both situations results to be negligible indistinctly of the approach used, semi-analytical or numerical. Thus, the actual limits from which the estimation of the AC losses can be used as an asset for the deployment of DC SC wires sharing the right of way with AC lines, against the sole use of SC wires for the transmission of AC transport current, are established.

Shapiro steps for skyrmion motion on a washboard potential with longitudinal and transverse ac drives

DOE PAGES

Reichhardt, Charles; Reichhardt, Cynthia Jane

2015-12-28

In this work, we numerically study the behavior of two-dimensional skyrmions in the presence of a quasi-one-dimensional sinusoidal substrate under the influence of externally applied dc and ac drives. In the overdamped limit, when both dc and ac drives are aligned in the longitudinal direction parallel to the direction of the substrate modulation, the velocity-force curves exhibit classic Shapiro step features when the frequency of the ac drive matches the washboard frequency that is dynamically generated by the motion of the skyrmions over the substrate, similar to previous observations in superconducting vortex systems. In the case of skyrmions, the additionalmore » contribution to the skyrmion motion from a nondissipative Magnus force shifts the location of the locking steps to higher dc drives, and we find that the skyrmions move at an angle with respect to the direction of the dc drive. For a longitudinal dc drive and a perpendicular or transverse ac drive, the overdamped system exhibits no Shapiro steps; however, when a finite Magnus force is present, we find pronounced transverse Shapiro steps along with complex two-dimensional periodic orbits of the skyrmions in the phase-locked regimes. Both the longitudinal and transverse ac drives produce locking steps whose widths oscillate with increasing ac drive amplitude. We examine the role of collective skyrmion interactions and find that additional fractional locking steps occur for both longitudinal and transverse ac drives. Finally, at higher skyrmion densities, the system undergoes a series of dynamical order-disorder transitions, with the skyrmions forming a moving solid on the phase locking steps and a fluctuating dynamical liquid in regimes between the steps.« less

The DC and AC insulating properties of magnetic fluids based on transformer oil

NASA Astrophysics Data System (ADS)

Tomo, L.; Marton, K.; Herchl, F.; Kopanský, P.; Potoová, I.; Koneracká, M.; Timko, M.

2006-01-01

The AC-dielectric breakdown was investigated in magnetic fluids based on transformer oil TECHNOL US 4000 for two orientations of external magnetic field (B E and B E) and in B = 0. The found results were compared with those obtained formerly for the DC-dielectric breakdown. The observations of the time development of the AC-dielectric breakdown showed the presence of partial discharges long before the complete breakdown occurrence, while for DC-dielectric breakdown a complete breakdown of the gap next to the onset of a measurable ionization was characteristic. The comparison of the AC-dielectric breakdown strengths of pure transformer oil and transformer-oil-based magnetic fluid showed better dielectric properties of magnetic fluid in external magnetic field and comparable, but not worse, in B = 0. Regarding to the better heat transfer, provided by magnetic fluids, they could be used in power transformers as insulating fluids.

Simultaneous hyperthermia and doxorubicin delivery from polymer-coated magnetite nanoparticles

NASA Astrophysics Data System (ADS)

Iglesias, G. R.; Delgado, A. V.; González-Caballero, F.; Ramos-Tejada, M. M.

2017-06-01

In this work, the hyperthermia response, (i.e., heating induced by an externally applied alternating magnetic field) and the simultaneous release of an anti-cancer drug (doxorubicin) by polymer-coated magnetite nanoparticles have been investigated. After describing the setup for hyperthermia measurements in suspensions of magnetic nanoparticles, the hyperthermia (represented by the rate of suspension heating and, ultimately, by the specific absorption rate or SAR) of magnetite nanoparticles (both bare and polymer-coated as drug nanocarriers) is discussed. The effect of the applied ac magnetic field on doxorubicin release is also studied, and it is concluded that the field does not interfere with the release process, demonstrating the double functionality of the investigated particles.

Numerical Simulations of Plasma Based Flow Control Applications

NASA Technical Reports Server (NTRS)

Suzen, Y. B.; Huang, P. G.; Jacob, J. D.; Ashpis, D. E.

2005-01-01

A mathematical model was developed to simulate flow control applications using plasma actuators. The effects of the plasma actuators on the external flow are incorporated into Navier Stokes computations as a body force vector. In order to compute this body force vector, the model solves two additional equations: one for the electric field due to the applied AC voltage at the electrodes and the other for the charge density representing the ionized air. The model is calibrated against an experiment having plasma-driven flow in a quiescent environment and is then applied to simulate a low pressure turbine flow with large flow separation. The effects of the plasma actuator on control of flow separation are demonstrated numerically.

Assessment of three AC electroosmotic flow protocols for mixing in microfluidic channel.

PubMed

Chen, Jia-Kun; Weng, Chi-Neng; Yang, Ruey-Jen

2009-05-07

This study performs an experimental investigation into the micromixer capabilities of three different protocols of AC electroosmotic flow (AC EOF), namely capacitive charging (CC), Faradaic charging (FC) and asymmetric polarization (AP). The results reveal that the vortices generated by the FC protocol (the frequency is around 50-350 Hz) are stronger than those induced by the CC protocol (the frequency is higher than 350 Hz), and therefore provide an improved mixing effect. However, in the FC protocol, the frequency of the external AC voltage must be carefully controlled to avoid damaging electrodes as a result of Faradaic reactions. The experimental results indicate that the AP polarization effect (the applied voltage and frequency are V(1) = 1 V(pp) and V(2) = 20 V(pp)/5 kHz) induces more powerful vortices than either the CC protocol or the FC protocol, and therefore yields a better mixing performance. Two AP-based micromixers are fabricated with symmetric and asymmetric electrode configurations, respectively. The mixing indices achieved by the two devices after an elapsed time of 60 seconds are found to be 56.49 % and 71.77 %, respectively. This result shows that of the two devices, an asymmetric electrode configuration represents a more suitable choice for micromixer in microfluidic devices.

Forced transport of self-propelled particles in a two-dimensional separate channel.

PubMed

Wu, Jian-chun; Ai, Bao-quan

2016-04-01

Transport of self-propelled particles in a two-dimensional (2D) separate channel is investigated in the presence of the combined forces. By applying an ac force, the particles will be trapped by the separate walls. A dc force produces the asymmetry of the system and induces the longitudinal directed transport. Due to the competition between self-propulsion and the combined external forces, the transport is sensitive to the self-propelled speed and the particle radius, thus one can separate the particles based on these properties.

External Magnetic Field Reduction Techniques for the Advanced Stirling Radioisotope Generator

NASA Technical Reports Server (NTRS)

Niedra, Janis M.; Geng, Steven M.

2013-01-01

Linear alternators coupled to high efficiency Stirling engines are strong candidates for thermal-to-electric power conversion in space. However, the magnetic field emissions, both AC and DC, of these permanent magnet excited alternators can interfere with sensitive instrumentation onboard a spacecraft. Effective methods to mitigate the AC and DC electromagnetic interference (EMI) from solenoidal type linear alternators (like that used in the Advanced Stirling Convertor) have been developed for potential use in the Advanced Stirling Radioisotope Generator. The methods developed avoid the complexity and extra mass inherent in data extraction from multiple sensors or the use of shielding. This paper discusses these methods, and also provides experimental data obtained during breadboard testing of both AC and DC external magnetic field devices.

Ratchet Effects in Active Matter Systems

NASA Astrophysics Data System (ADS)

Reichhardt, C. J. Olson; Reichhardt, C.

2017-03-01

Ratchet effects can arise for single or collectively interacting Brownian particles on an asymmetric substrate when a net dc transport is produced by an externally applied ac driving force or by periodically flashing the substrate. Recently, a new class of active ratchet systems that do not require the application of external driving has been realized through the use of active matter; they are self-propelled units that can be biological or nonbiological in nature. When active materials such as swimming bacteria interact with an asymmetric substrate, a net dc directed motion can arise even without external driving, opening a wealth of possibilities such as sorting, cargo transport, or micromachine construction. We review the current status of active matter ratchets for swimming bacteria, cells, active colloids, and swarming models, focusing on the role of particle-substrate interactions. We describe ratchet reversals produced by collective effects and the use of active ratchets to transport passive particles. We discuss future directions including deformable substrates or particles, the role of different swimming modes, varied particle-particle interactions, and nondissipative effects.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reichhardt, Cynthia Jane; Reichhardt, Charles

Ratchet effects can arise for single or collectively interacting Brownian particles on an asymmetric substrate when a net dc transport is produced by an externally applied ac driving force or by periodically flashing the substrate. Recently, a new class of active ratchet systems that do not require the application of external driving has been realized through the use of active matter; they are self-propelled units that can be biological or nonbiological in nature. When active materials such as swimming bacteria interact with an asymmetric substrate, a net dc directed motion can arise even without external driving, opening a wealth ofmore » possibilities such as sorting, cargo transport, or micromachine construction. We review the current status of active matter ratchets for swimming bacteria, cells, active colloids, and swarming models, focusing on the role of particle-substrate interactions. Here, we describe ratchet reversals produced by collective effects and the use of active ratchets to transport passive particles. We discuss future directions including deformable substrates or particles, the role of different swimming modes, varied particle–particle interactions, and nondissipative effects.« less

75 FR 16957 - Energy Conservation Program: Test Procedures for Battery Chargers and External Power Supplies

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-02

... Procedures C. Review of Single-Voltage External Power Supply Test Procedure D. Multiple-Voltage External...) Deletions of Existing Definitions (b) Revisions to Existing Definitions (c) Additions of New Definitions 4. Test Apparatus and General Instructions (a) Confidence Intervals (b) Temperature (c) AC Input Voltage...

Giant Magnetoimpedance for Biosensing in Drug Delivery

NASA Astrophysics Data System (ADS)

Fal-Miyar, Vanesa; Kumar, Arun; Mohapatra, Shyam; Shirley, Shawna; Frey, Natalie A.; Barandiarán, José M.; Kurlyandskaya, Galina V.

2008-06-01

Iron oxide (Fe3O4) non-specific superparamagnetic nanoparticles of 30 nm size are introduced into human embryonic kidney (HEK-293) cells by intracellular uptake. The nanoparticles are magnetised by two superimposed magnetic fields, an externally applied DC field and an AC field generated by the high-frequency current flowing through Co64.5Fe2.5Cr3Si15B15 amorphous ribbons. The resulted fringe fields from the nanoparticles are detected via the magnetoimpedance change in the ribbons covered and uncovered by thin gold layer. The gold covering is considered an improvement due to its biocompatibility and because it avoids the biocorrosion process on the ribbon. The MI responses in both cases are clearly dependent on the presence of the magnetic nanoparticles inside the cells and on the value of the external field.

Optical tweezers with 2.5 kHz bandwidth video detection for single-colloid electrophoresis

NASA Astrophysics Data System (ADS)

Otto, Oliver; Gutsche, Christof; Kremer, Friedrich; Keyser, Ulrich F.

2008-02-01

We developed an optical tweezers setup to study the electrophoretic motion of colloids in an external electric field. The setup is based on standard components for illumination and video detection. Our video based optical tracking of the colloid motion has a time resolution of 0.2ms, resulting in a bandwidth of 2.5kHz. This enables calibration of the optical tweezers by Brownian motion without applying a quadrant photodetector. We demonstrate that our system has a spatial resolution of 0.5nm and a force sensitivity of 20fN using a Fourier algorithm to detect periodic oscillations of the trapped colloid caused by an external ac field. The electrophoretic mobility and zeta potential of a single colloid can be extracted in aqueous solution avoiding screening effects common for usual bulk measurements.

Static and Alternating Field Magnetic Capture and Heating of Iron Oxide Nanoparticles in Simulated Blood Vessels

NASA Astrophysics Data System (ADS)

Lee, Joanne Haeun; Shah, Rhythm R.; Brazel, Christopher S.

2014-11-01

Targeted drug delivery and localized hyperthermia are being studied as alternatives to conventional cancer treatments, which can affect the whole body and indiscriminately kill healthy cells. Magnetic nanoparticles (MNPs) have potential as drug carriers that can be captured and trigger hyperthermia at the site of the tumor by applying an external magnetic field. This study focuses on comparing the capture efficiency of the magnetic field applied by a static magnet to an alternating current coil. The effect of particle size, degree of dispersion, and the frequency of the AC field on capture and heating were studied using 3 different dispersions: 16 nm maghemite in water, 50 nm maghemite in dopamine, and 20--30 nm magnetite in dimercaptosuccinic acid. A 480G static field captured more MNPs than a similar 480G AC field at either 194 or 428 kHz; however, the AC field also allowed heating. The MNPs in water had a lower capture and heating efficiency than the larger, dopamine-coated MNPs. This finding was supported by dynamic light scattering data showing the particle size distribution and vibrating sample magnetometry data showing that the larger MNPs in the dopamine solution have a higher field of coercivity, exhibit ferrimagnetism and allow for better capture while smaller (16 nm) MNPs exhibit superparamagnetism. The dispersions that captured the best also heated the best. NSF ECE Grant #1358991 supported the first author as an REU student.

Mitigation of commutation failures in LCC-HVDC systems based on superconducting fault current limiters

NASA Astrophysics Data System (ADS)

Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook

2016-11-01

Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC-HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC-HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC-HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC-HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

Analysis of the Distribution of Magnetic Fluid inside Tumors by a Giant Magnetoresistance Probe

PubMed Central

Gooneratne, Chinthaka P.; Kurnicki, Adam; Yamada, Sotoshi; Mukhopadhyay, Subhas C.; Kosel, Jürgen

2013-01-01

Magnetic fluid hyperthermia (MFH) therapy uses the magnetic component of electromagnetic fields in the radiofrequency spectrum to couple energy to magnetic nanoparticles inside tumors. In MFH therapy, magnetic fluid is injected into tumors and an alternating current (AC) magnetic flux is applied to heat the magnetic fluid- filled tumor. If the temperature can be maintained at the therapeutic threshold of 42°C for 30 minutes or more, the tumor cells can be destroyed. Analyzing the distribution of the magnetic fluid injected into tumors prior to the heating step in MFH therapy is an essential criterion for homogenous heating of tumors, since a decision can then be taken on the strength and localization of the applied external AC magnetic flux density needed to destroy the tumor without affecting healthy cells. This paper proposes a methodology for analyzing the distribution of magnetic fluid in a tumor by a specifically designed giant magnetoresistance (GMR) probe prior to MFH heat treatment. Experimental results analyzing the distribution of magnetic fluid suggest that different magnetic fluid weight densities could be estimated inside a single tumor by the GMR probe. PMID:24312280

Electrodeformation of multi-bilayer spherical concentric membranes by AC electric fields

NASA Astrophysics Data System (ADS)

Lira-Escobedo, J.; Arauz-Lara, J.; Aranda-Espinoza, H.; Adlerz, K.; Viveros-Mendez, P. X.; Aranda-Espinoza, S.

2017-09-01

It is now well established that external stresses alter the behaviour of cells, where such alterations can be as profound as changes in gene expression. A type of stresses of particular interest are those due to alternating-current (AC) electric fields. The effect of AC fields on cells is still not well understood, in particular it is not clear how these fields affect the cell nucleus and other organelles. Here, we propose that one possible mechanism is through the deformation of the membranes. In order to investigate the effect of AC fields on the morphological changes of the cell organelles, we modelled the cell as two concentric bilayer membranes. This model allows us to obtain the deformations induced by the AC field by balancing the elastic energy and the work done by the Maxwell stresses. Morphological phase diagrams are obtained as a function of the frequency and the electrical properties of the media and membranes. We demonstrate that the organelle shapes can be changed without modifying the shape of the external cell membrane and that the organelle deformation transitions can be used to measure, for example, the conductivity of the nucleus.

Frequency and voltage dependent profile of dielectric properties, electric modulus and ac electrical conductivity in the PrBaCoO nanofiber capacitors

NASA Astrophysics Data System (ADS)

Demirezen, S.; Kaya, A.; Yerişkin, S. A.; Balbaşı, M.; Uslu, İ.

In this study, praseodymium barium cobalt oxide nanofiber interfacial layer was sandwiched between Au and n-Si. Frequency and voltage dependence of ε‧, ε‧, tanδ, electric modulus (M‧ and M″) and σac of PrBaCoO nanofiber capacitor have been investigated by using impedance spectroscopy method. The obtained experimental results show that the values of ε‧, ε‧, tanδ, M‧, M″ and σac of the PrBaCoO nanofiber capacitor are strongly dependent on frequency of applied bias voltage. The values of ε‧, ε″ and tanδ show a steep decrease with increasing frequency for each forward bias voltage, whereas the values of σac and the electric modulus increase with increasing frequency. The high dispersion in ε‧ and ε″ values at low frequencies may be attributed to the Maxwell-Wagner and space charge polarization. The high values of ε‧ may be due to the interfacial effects within the material, PrBaCoO nanofibers interfacial layer and electron effect. The values of M‧ and M″ reach a maximum constant value corresponding to M∞ ≈ 1/ε∞ due to the relaxation process at high frequencies, but both the values of M‧ and M″ approach almost to zero at low frequencies. The changes in the dielectric and electrical properties with frequency can be also attributed to the existence of Nss and Rs of the capacitors. As a result, the change in the ε‧, ε″, tanδ, M‧, M″ and ac electric conductivity (σac) is a result of restructuring and reordering of charges at the PrBaCoO/n-Si interface under an external electric field or voltage and interface polarization.

New perspectives on the dynamics of AC and DC plasma arcs exposed to cross-fields

NASA Astrophysics Data System (ADS)

Abdo, Youssef; Rohani, Vandad; Cauneau, François; Fulcheri, Laurent

2017-02-01

Interactions between an arc and external fields are crucially important for the design and the optimization of modern plasma torches. Multiple studies have been conducted to help better understand the behavior of DC and AC current arcs exposed to external and ‘self-induced’ magnetic fields, but the theoretical foundations remain very poorly explored. An analytical investigation has therefore been carried out in order to study the general behavior of DC and AC arcs under the effect of random cross-fields. A simple differential equation describing the general behavior of a planar DC or AC arc has been obtained. Several dimensionless numbers that depend primarily on arc and field parameters and the main arc characteristics (temperature, electric field strength) have also been determined. Their magnitude indicates the general tendency pattern of the arc evolution. The analytical results for many case studies have been validated using an MHD numerical model. The main purpose of this investigation was deriving a practical analytical model for the electric arc, rendering possible its stabilization and control, and the enhancement of the plasma torch power.

Transient electroosmotic flow induced by DC or AC electric fields in a curved microtube.

PubMed

Luo, W-J

2004-10-15

This study investigates transient electroosmotic flow in a rectangular curved microtube in which the fluid is driven by the application of an external DC or AC electric field. The resultant flow-field evolutions within the microtube are simulated using the backwards-Euler time-stepping numerical method to clarify the relationship between the changes in the axial-flow velocity and the intensity of the applied electric field. When the electric field is initially applied or varies, the fluid within the double layer responds virtually immediately, and the axial velocity within the double layer tends to follow the varying intensity of the applied electric field. The greatest net charge density exists at the corners of the microtube as a result of the overlapping electrical double layers of the two walls. It results in local maximum or minimum axial velocities in the corners during increasing or decreasing applied electric field intensity in either the positive or negative direction. As the fluid within the double layer starts to move, the bulk fluid is gradually dragged into motion through the diffusion of momentum from the double layer. A finite time is required for the full momentum of the double layer to diffuse to the bulk fluid; hence, a certain phase shift between the applied electric field and the flow response is inevitable. The patterns of the axial velocity contours during the transient evolution are investigated in this study. It is found that these patterns are determined by the efficiency of momentum diffusion from the double layer to the central region of the microtube.

Resonance of scroll rings with periodic external fields in excitable media

NASA Astrophysics Data System (ADS)

Pan, De-Bei; Li, Qi-Hao; Zhang, Hong

2018-06-01

By direct numerical simulations of a chemical reaction-diffusion system coupled to a periodic external AC electric field with frequency equal to double frequency of the scroll wave rotation, we find that scroll rings resonate with the electric field and exhibit various dynamical behaviors, for example, their reversals, collapses, or growths, depending both on the initial phase of AC electric fields and on the initial phase of scroll rings. A kinematical model characterizing the drift velocity of the scroll rings along their radial directions as well as that of the scroll rings along their symmetry axes is proposed, which can effectively account for the numerical observations and predict the behaviors of the scroll rings. Besides, the existence of the equilibrium state of a scroll ring under the AC electric fields is predicted by the kinematical model and the predictions agree well with the simulations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gallego-Marcos, Fernando; Sánchez, Rafael; Platero, Gloria

We analyze long-range transport through an ac driven triple quantum dot with a single electron. Resonant transitions between separated and detuned dots are mediated by the exchange of n photons with the time-dependent field. An effective model is proposed in terms of second order (cotunneling) processes which dominate the long-range transport between the edge quantum dots. The ac field renormalizes the inter dot hopping, modifying the level hybridization. It results in a non-trivial behavior of the current with the frequency and amplitude of the external ac field.

Ratchet Effects in Active Matter Systems

DOE PAGES

Reichhardt, Cynthia Jane; Reichhardt, Charles

2016-12-21

Ratchet effects can arise for single or collectively interacting Brownian particles on an asymmetric substrate when a net dc transport is produced by an externally applied ac driving force or by periodically flashing the substrate. Recently, a new class of active ratchet systems that do not require the application of external driving has been realized through the use of active matter; they are self-propelled units that can be biological or nonbiological in nature. When active materials such as swimming bacteria interact with an asymmetric substrate, a net dc directed motion can arise even without external driving, opening a wealth ofmore » possibilities such as sorting, cargo transport, or micromachine construction. We review the current status of active matter ratchets for swimming bacteria, cells, active colloids, and swarming models, focusing on the role of particle-substrate interactions. Here, we describe ratchet reversals produced by collective effects and the use of active ratchets to transport passive particles. We discuss future directions including deformable substrates or particles, the role of different swimming modes, varied particle–particle interactions, and nondissipative effects.« less

Finite-size effects on the static properties of a single-chain magnet

NASA Astrophysics Data System (ADS)

Bogani, L.; Sessoli, R.; Pini, M. G.; Rettori, A.; Novak, M. A.; Rosa, P.; Massi, M.; Fedi, M. E.; Giuntini, L.; Caneschi, A.; Gatteschi, D.

2005-08-01

We study the role of defects in the “single-chain magnet” CoPhOMe by inserting a controlled number of diamagnetic impurities. The samples are analyzed with unprecedented accuracy with the particle induced x-ray emission technique, and with ac and dc magnetic measurements. In an external applied field the system shows an unexpected behavior, giving rise to a double peak in the susceptibility. The static thermodynamic properties of the randomly diluted Ising chain with alternating g values are then exactly obtained via a transfer matrix approach. These results are compared to the experimental behavior of CoPhOMe, showing qualitative agreement.

Remote Powering and Steering of Self-Propelling Microdevices by Modulated Electric Field

NASA Astrophysics Data System (ADS)

Sharma, Rachita; Velev, Orlin

2011-03-01

We have demonstrated a new class of self-propelling particles based on semiconductor diodes powered by an external uniform alternating electric field. The millimeter-sized diodes floating in water rectify the applied voltage. The resulting particle-localized electroosmotic flux propels them in the direction of the cathode or the anode depending on their surface charge. These particles suggest solutions to problems facing self-propelling microdevices, and have potential for a range of additional functions. The next step in this direction is the steering of these devices. We will present a novel technique that allows on-demand steering of these self-propelling diodes. We control remotely their direction of motion by modifying the duty cycle of the applied AC field. The diodes change their direction of motion when a DC component (wave asymmetry) is introduced into the AC signal. The DC component leads to redistribution of the counterions near the diode surface. The electric field resulting from this counterion redistribution exerts a torque on the dipole across the diode, causing its rotation. Thus, the reversal of the direction of the electroosmotic flux caused by field asymmetry leads to reversal of the direction of diode motion. This new principle of steering of self-propelling diodes can find applications in MEMs and micro-robotics.

Magnetite nano-islands on Graphene

NASA Astrophysics Data System (ADS)

Anderson, Nathaniel; Zhang, Qiang; Rosenberg, Richard; Vaknin, David

X-ray magnetic circular dichroism (XMCD) of ex-situ iron nano-islands grown on graphene reveals that iron oxidation spontaneously leads to the formation of magnetite nano-particles - i.e, the formation of the inverse spinel Fe3O4. Fe islands have been grown with two different heights (20 and 75 MLs) on epitaxial graphene and we have determined their magnetic behavior both as function of temperature and applied external field. Our XAS and XMCD at an applied magnetic field of B = 5 T show that the thin film (20 MLs) is totally converted to magnetite whereas the thicker film (75 MLs) exhibits magnetite properties but also those of pure metal iron. For both samples, temperature dependence of the XMCD shows clear transitions at ~120 K consistent with the Verwey transition of bulk magnetite. XMCD at low temperatures shows a weak hysteresis and provide the average spin and angular-momentum moments, the dipolar term, and the total moment . In addition, manipulation and comparison of the XMCD data from both samples allows us to extract information about the pure iron nano-islands from the thicker sample. Ames Laboratory is supported by the U.S. DOE, BES, MSE Contract No. DE-AC02-07CH11358. APS is supported by U.S. DOE Contract No. DE-AC02-06CH11357.

Responses of Lumbriculus variegatus to activated carbon amendments in uncontaminated sediments.

PubMed

Nybom, Inna; Werner, David; Leppänen, Matti T; Siavalas, George; Christanis, Kimon; Karapanagioti, Hrissi K; Kukkonen, Jussi V K; Akkanen, Jarkko

2012-12-04

Activated carbon (AC) amendment is a recently developed sediment remediation method. The strong hydrophobic organic contaminant sorption efficiency of AC has been shown in several studies, but effects on benthic organisms require more investigation. The AC induced effects on egestion rate, growth and reproduction of Lumbriculus variegatus were studied by applying bituminous coal based AC in three different particle size fractions, namely <63 μm (90%, AC(p)), 63-200 μm (AC(m)) and 1000 μm (AC(g)), to natural uncontaminated (HS) and artificial sediment (AS). Egestion rate, growth and reproduction decreased with increasing AC concentration and finer AC particle fractions, effects being stronger on HS than on AS sediment. Lipid content in AS was reduced already at the lowest AC doses applied (AC(p) and AC(m) 0.05%, AC(g) 0.25%). In addition, hormesis-like response was observed in growth (AS) and reproduction (AS, HS) indicating that AC may disturb organisms even at very low doses. Potential ecological effects need to be further evaluated in an amendment- and site-specific manner.

[Influence of surface chemical properties and pore structure characteristics of activated carbon on the adsorption of nitrobenzene from aqueous solution].

PubMed

Liu, Shou-Xin; Chen, Xi; Zhang, Xian-Quan

2008-05-01

Commercial activated carbon was treated by HNO3 oxidation and then subsequently heat treated under N2 atmosphere. Effect of surface chemical properties and pore structure on the adsorption performance of nitrobenzene was investigated. N2/77K adsorption isotherm and scanning electron microscopy (SEM) were used to characterize the pore structure and surface morphology of carbon. Boehm titration, Fourier transform infrared spectroscopy (FTIR), the point of zero charge (pH(PZC)) measurement and elemental analysis were used to characterize the surface properties. The results reveal that HNO3 oxidation can modify the surface chemical properties, increase the number of acidic surface oxygen-containing groups and has trivial effect on the pore structure of carbon. Further heat treatment can cause the decomposition of surface oxygen-containing groups, and increase the external surface area and the number of mesopores. Adsorption capacity of nitrobenzene on AC(NO-T), AC(raw) and AC(NO) was 1011.31, 483.09 and 321.54 mg x g(-1), respectively. Larger external surface area and the number of meso-pores, together with the less acid surface oxygen-containing groups were the main reason for the larger adsorption capacity AC(NO-T).

Visco-Resistive MHD Modeling Benchmark of Forced Magnetic Reconnection

NASA Astrophysics Data System (ADS)

Beidler, M. T.; Hegna, C. C.; Sovinec, C. R.; Callen, J. D.; Ferraro, N. M.

2016-10-01

The presence of externally-applied 3D magnetic fields can affect important phenomena in tokamaks, including mode locking, disruptions, and edge localized modes. External fields penetrate into the plasma and can lead to forced magnetic reconnection (FMR), and hence magnetic islands, on resonant surfaces if the local plasma rotation relative to the external field is slow. Preliminary visco-resistive MHD simulations of FMR in a slab geometry are consistent with theory. Specifically, linear simulations exhibit proper scaling of the penetrated field with resistivity, viscosity, and flow, and nonlinear simulations exhibit a bifurcation from a flow-screened to a field-penetrated, magnetic island state as the external field is increased, due to the 3D electromagnetic force. These results will be compared to simulations of FMR in a circular cross-section, cylindrical geometry by way of a benchmark between the NIMROD and M3D-C1 extended-MHD codes. Because neither this geometry nor the MHD model has the physics of poloidal flow damping, the theory of will be expanded to include poloidal flow effects. The resulting theory will be tested with linear and nonlinear simulations that vary the resistivity, viscosity, flow, and external field. Supported by OFES DoE Grants DE-FG02-92ER54139, DE-FG02-86ER53218, DE-AC02-09CH11466, and the SciDAC Center for Extended MHD Modeling.

AC Initiation System.

DTIC Science & Technology

An ac initiation system is described which uses three ac transmission signals interlocked for safety by frequency, phase, and power discrimination...The ac initiation system is pre-armed by the application of two ac signals have the proper phases, and activates a load when an ac power signal of the proper frequency and power level is applied. (Author)

Changes in driving behavior and cognitive performance with different breath alcohol concentration levels.

PubMed

Liu, Yung-Ching; Fu, Shing-Mei

2007-06-01

This study examines the changes in driving behavior and cognitive performance of drivers with different breath alcohol concentration (BrAC) levels. Eight licensed drivers, aged between 20 and 30 years, with BrAC levels of 0.00, 0.25, 0.4 and 0.5 mg/l performed simulated driving tests under high- and low-load conditions. Subjects were asked to assess their subjective psychological load at specified intervals and perform various tasks. The outcome was measured in terms of reaction times for task completion, accuracy rates, and driver's driving behavior. The effects of BrAC vary depending on the task. Performance of tasks involving attention shift, information processing, and short-term memory showed significant deterioration with increasing BrAC, while dangerous external vehicle driving behavior occurred only when the BrAC reached 0.4 mg/l and the deterioration was marked. We can conclude that the cognitive faculty is the first to be impaired by drinking resulting in deteriorated performance in tasks related to divided attention, short-term memory, logical reasoning, followed by visual perception. On the other hand, increasing alcohol dose may not pose an immediate impact on the external vehicle driving behavior but may negatively affect the driver's motor behavior even at low BrAC levels. Experience and will power could compensate for the negative influence of alcohol enabling the drivers to remain in full steering control. This lag between alcohol consumption and impaired driving performance may mislead the drivers in thinking that they are still capable of safe steering and cause them to ignore the potential dangers of drunk driving.

Screening length and quantum capacitance in graphene by scanning probe microscopy.

PubMed

Giannazzo, F; Sonde, S; Raineri, V; Rimini, E

2009-01-01

A nanoscale investigation on the capacitive behavior of graphene deposited on a SiO2/n(+) Si substrate (with SiO2 thickness of 300 or 100 nm) was carried out by scanning capacitance spectroscopy (SCS). A bias V(g) composed by an AC signal and a slow DC voltage ramp was applied to the macroscopic n(+) Si backgate of the graphene/SiO(2)/Si capacitor, while a nanoscale contact was obtained on graphene by the atomic force microscope tip. This study revealed that the capacitor effective area (A(eff)) responding to the AC bias is much smaller than the geometrical area of the graphene sheet. This area is related to the length scale on which the externally applied potential decays in graphene, that is, the screening length of the graphene 2DEG. The nonstationary charges (electrons/holes) induced by the AC potential spread within this area around the contact. A(eff) increases linearly with the bias and in a symmetric way for bias inversion. For each bias V(g), the value of A(eff) is related to the minimum area necessary to accommodate the not stationary charges, according to the graphene density of states (DOS) at V(g). Interestingly, by decreasing the SiO(2) thickness from 300 to 100 nm, the slope of the A(eff) versus bias curve strongly increases (by a factor of approximately 50). The local quantum capacitance C(q) in the contacted graphene region was calculated starting from the screening length, and the distribution of the values of C(q) for different tip positions was obtained. Finally the lateral variations of the DOS in graphene was determined.

Lasting EEG/MEG Aftereffects of Rhythmic Transcranial Brain Stimulation: Level of Control Over Oscillatory Network Activity

PubMed Central

Veniero, Domenica; Vossen, Alexandra; Gross, Joachim; Thut, Gregor

2015-01-01

A number of rhythmic protocols have emerged for non-invasive brain stimulation (NIBS) in humans, including transcranial alternating current stimulation (tACS), oscillatory transcranial direct current stimulation (otDCS), and repetitive (also called rhythmic) transcranial magnetic stimulation (rTMS). With these techniques, it is possible to match the frequency of the externally applied electromagnetic fields to the intrinsic frequency of oscillatory neural population activity (“frequency-tuning”). Mounting evidence suggests that by this means tACS, otDCS, and rTMS can entrain brain oscillations and promote associated functions in a frequency-specific manner, in particular during (i.e., online to) stimulation. Here, we focus instead on the changes in oscillatory brain activity that persist after the end of stimulation. Understanding such aftereffects in healthy participants is an important step for developing these techniques into potentially useful clinical tools for the treatment of specific patient groups. Reviewing the electrophysiological evidence in healthy participants, we find aftereffects on brain oscillations to be a common outcome following tACS/otDCS and rTMS. However, we did not find a consistent, predictable pattern of aftereffects across studies, which is in contrast to the relative homogeneity of reported online effects. This indicates that aftereffects are partially dissociated from online, frequency-specific (entrainment) effects during tACS/otDCS and rTMS. We outline possible accounts and future directions for a better understanding of the link between online entrainment and offline aftereffects, which will be key for developing more targeted interventions into oscillatory brain activity. PMID:26696834

Induced charge electroosmosis micropumps using arrays of Janus micropillars.

PubMed

Paustian, Joel S; Pascall, Andrew J; Wilson, Neil M; Squires, Todd M

2014-09-07

We report on a microfluidic AC-driven electrokinetic pump that uses Induced Charge Electro-Osmosis (ICEO) to generate on-chip pressures. ICEO flows occur when a bulk electric field polarizes a metal object to induce double layer formation, then drives electroosmotic flow. A microfabricated array of metal-dielectric Janus micropillars breaks the symmetry of ICEO flow, so that an AC electric field applied across the array drives ICEO flow along the length of the pump. When pumping against an external load, a pressure gradient forms along the pump length. The design was analyzed theoretically with the reciprocal theorem. The analysis reveals a maximum pressure and flow rate that depend on the ICEO slip velocity and micropillar geometry. We then fabricate and test the pump, validating our design concept by demonstrating non-local pressure driven flow using local ICEO slip flows. We varied the voltage, frequency, and electrolyte composition, measuring pump pressures of 15-150 Pa. We use the pump to drive flows through a high-resistance microfluidic channel. We conclude by discussing optimization routes suggested by our theoretical analysis to enhance the pump pressure.

Accurate calculation and modeling of the adiabatic connection in density functional theory

NASA Astrophysics Data System (ADS)

Teale, A. M.; Coriani, S.; Helgaker, T.

2010-04-01

Using a recently implemented technique for the calculation of the adiabatic connection (AC) of density functional theory (DFT) based on Lieb maximization with respect to the external potential, the AC is studied for atoms and molecules containing up to ten electrons: the helium isoelectronic series, the hydrogen molecule, the beryllium isoelectronic series, the neon atom, and the water molecule. The calculation of AC curves by Lieb maximization at various levels of electronic-structure theory is discussed. For each system, the AC curve is calculated using Hartree-Fock (HF) theory, second-order Møller-Plesset (MP2) theory, coupled-cluster singles-and-doubles (CCSD) theory, and coupled-cluster singles-doubles-perturbative-triples [CCSD(T)] theory, expanding the molecular orbitals and the effective external potential in large Gaussian basis sets. The HF AC curve includes a small correlation-energy contribution in the context of DFT, arising from orbital relaxation as the electron-electron interaction is switched on under the constraint that the wave function is always a single determinant. The MP2 and CCSD AC curves recover the bulk of the dynamical correlation energy and their shapes can be understood in terms of a simple energy model constructed from a consideration of the doubles-energy expression at different interaction strengths. Differentiation of this energy expression with respect to the interaction strength leads to a simple two-parameter doubles model (AC-D) for the AC integrand (and hence the correlation energy of DFT) as a function of the interaction strength. The structure of the triples-energy contribution is considered in a similar fashion, leading to a quadratic model for the triples correction to the AC curve (AC-T). From a consideration of the structure of a two-level configuration-interaction (CI) energy expression of the hydrogen molecule, a simple two-parameter CI model (AC-CI) is proposed to account for the effects of static correlation on the AC. When parametrized in terms of the same input data, the AC-CI model offers improved performance over the corresponding AC-D model, which is shown to be the lowest-order contribution to the AC-CI model. The utility of the accurately calculated AC curves for the analysis of standard density functionals is demonstrated for the BLYP exchange-correlation functional and the interaction-strength-interpolation (ISI) model AC integrand. From the results of this analysis, we investigate the performance of our proposed two-parameter AC-D and AC-CI models when a simple density functional for the AC at infinite interaction strength is employed in place of information at the fully interacting point. The resulting two-parameter correlation functionals offer a qualitatively correct behavior of the AC integrand with much improved accuracy over previous attempts. The AC integrands in the present work are recommended as a basis for further work, generating functionals that avoid spurious error cancellations between exchange and correlation energies and give good accuracy for the range of densities and types of correlation contained in the systems studied here.

Thermoplastic-based conductive composites containing multi-wall carbon nanotubes aligned under the application of external electric fields

NASA Astrophysics Data System (ADS)

Osazuwa, Osayuki

The objective of this thesis is to prepare thermoplastic/multi-wall carbon nanotubes (MWCNTs) and to apply external alternating current (AC) electric fields to achieve enhanced conductivity and dielectric properties. The first part of the thesis focuses on preparing polyolefin-based composites containing welldispersed MWCNTs. MWCNTs are functionalized with a hyperbranched polyethylene (HBPE) using a non-covalent, non-specific functionalization approach and melt compounded with an ethylene-octene copolymer (EOC) matrix. The improved filler dispersion in the functionalized EOC/MWCNT composite results in higher elongation at break compared to the non-functionalized composite. However, the electrical percolation threshold and the ultimate conductivity of the composites are not affected considerably, suggesting that this functionalization approach leaves the inherent properties of the nanotubes intact. EOC/HBPE-functionalized MWCNT composites are further subjected to external AC electric fields (35 -- 212 kV/m), which induce the formation of aligned columnar structures, as evidenced by Scanning Electron Microscopy. Experimentally acquired resistivity data are used to derive correlations between the characteristic insulator-to-conductor transition times of the composites and the electric field strength (E), polymer viscosity (eta) and MWCNT volume fraction (φ). A criterion for the selection of (eta, E, φ) conditions that enable MWCNT assembly under an electric field controlled regime (minimal Brownian motion-driven aggregation effects) is developed. The dielectric properties of the solidified aligned EOC/MWCNT composites are further studied using dielectric spectroscopy. Annealing of the composites at 160 °C results in the formation of interconnected structures, whereas electrification, using AC field of 71 and 212 kV/m induces the formation of aligned columnar structures. The electrified and annealed composites have increased real and imaginary permittivity compared to the as-compounded composite, resulting in improved conductivity and storage capacity. An equivalent circuit model is fitted to the experimentally obtained impedance data in order to correlate the effects of electric field and processing time to the dielectric characteristics of the treated composites. Finally poly(ethylene succinate) (PESu) composites containing well-dispersed MWCNT were prepared by an in-situ polymerization method. Composite electrification results in improvements in the electrical conductivity by up to 12 orders of magnitude, and a retention of high conductivity in the solidified state.

Flicker sensitivity as a function of target area with and without temporal noise.

PubMed

Rovamo, J; Donner, K; Näsänen, R; Raninen, A

2000-01-01

Flicker sensitivities (1-30 Hz) in foveal, photopic vision were measured as functions of stimulus area with and without strong external white temporal noise. Stimuli were circular, sinusoidally flickering sharp-edged spots of variable diameters (0.25-4 degrees ) but constant duration (2 s), surrounded by a uniform equiluminant field. The data was described with a model comprising (i) low-pass filtering in the retina (R), with a modulation transfer function (MTF) of a form derived from responses of cones; (ii) normalisation of the temporal luminance distribution by the average luminance; (iii) high-pass filtering by postreceptoral neural pathways (P), with an MTF proportional to temporal frequency; (iv) addition of internal white neural noise (N(i)); (v) integration over a spatial window; and (vi) detection by a suboptimal temporal matched filter of efficiency eta. In strong external noise, flicker sensitivity was independent of spot area. Without external noise, sensitivity increased with the square root of stimulus area (Piper's law) up to a critical area (A(c)), where it reaches a maximum level (S(max)). Both A(c) and eta were monotonic functions of temporal frequency (f), such that log A(c) increased and log eta decreased linearly with log f. Remarkably, the increase in spatial integration area and the decrease in efficiency were just balanced, so A(c)(f)eta(f) was invariant against f. Thus the bandpass characteristics of S(max)(f) directly reflected the composite effect of the distal filters R(f) and P(f). The temporal equivalent (N(it)) of internal neural noise (N(i)) decreased in inverse proportion to spot area up to A(c) and then stayed constant indicating that spatially homogeneous signals and noise are integrated over the same area.

Characterizing superconducting thin films using AC Magnetic Susceptibility

NASA Astrophysics Data System (ADS)

Mahoney, C. H.; Porzio, J.; Sullivan, M. C.

2014-03-01

We present our work on using ac magnetic susceptibility to determine the critical temperature of superconducting thin films. In ac magnetic susceptibility, the thin film is placed between two coils. One coil carries an ac signal, creating a varying external magnetic field. We measure the voltage induced in the pick-up coil on the opposite side of the sample and measure how the sample magnetization changes as the temperature changes. We will present our work to use ac susceptibility to determine critical temperature and superconducting volume fraction. Using our own analysis program, we are able to accurately locate the critical temperatures of the samples and determine the transition width. For the superconducting volume fraction, we etch samples in order to control the thicknesses of the sample and measure how much of the material grown on the surface is superconducting. Supported by NFS grant DMR-1305637.

An AC electroosmotic micropump for circular chromatographic applications.

PubMed

Debesset, S; Hayden, C J; Dalton, C; Eijkel, J C T; Manz, A

2004-08-01

Flow rates of up to 50 microm s(-1) have been successfully achieved in a closed-loop channel using an AC electroosmotic pump. The AC electroosmotic pump is made of an interdigitated array of unequal width electrodes located at the bottom of a channel, with an AC voltage applied between the small and the large electrodes. The flow rate was found to increase linearly with the applied voltage and to decrease linearly with the applied frequency. The pump is expected to be suitable for circular chromatography for the following reasons: the driving forces are distributed over the channel length and the pumping direction is set by the direction of the interdigitated electrodes. Pumping in a closed-loop channel can be achieved by arranging the electrode pattern in a circle. In addition the inherent working principle of AC electroosmotic pumping enables the independent optimisation of the channel height or the flow velocity.

Fabrication of a self-sensing electroactive polymer bimorph actuator based on polyvinylidene fluoride and its electrostrictive terpolymer

NASA Astrophysics Data System (ADS)

Engel, Leeya; Van Volkinburg, Kyle R.; Ben-David, Moti; Washington, Gregory N.; Krylov, Slava; Shacham-Diamand, Yosi

2016-04-01

In this paper, we report on the fabrication of a self-sensing electroactive polymer cantilevered bimorph beam actuator and its frequency response. Tip deflections of the beam, induced by applying an AC signal across ferroelectric relaxor polyvinylidene fluoride-trifluoroethylene chlorotrifluoroethylene (P(VDF-TrFE-CTFE)), reached a magnitude of 350μm under a field of ~55MV/m and were recorded externally using a laser Doppler vibrometer (LDV). Deflections were determined simultaneously by applying a sensing model to the voltage measured across the bimorph's integrated layer of piezoelectric polymer polyvinylidene fluoride (PVDF). The sensing model treats the structure as a simple Euler- Bernoulli cantilevered beam with two distributed active elements represented through the use of generalized functions and offers a method through which real time tip deflection can be measured without the need for external visualization. When not being used as a sensing element, the PVDF layer can provide an additional means for actuation of the beam via the converse piezoelectric effect, resulting in bidirectional control of the beam's deflections. Integration of flexible sensing elements together with modeling of the electroactive polymer beam can benefit the developing field of polymer microactuators which have applications in soft robotics as "smart" prosthetics/implants, haptic displays, tools for less invasive surgery, and sensing.

Influence of radius of cylinder HTS bulk on guidance force in a maglev vehicle system

NASA Astrophysics Data System (ADS)

Longcai, Zhang

2014-07-01

Bulk superconductors had great potential for various engineering applications, especially in a high-temperature superconducting (HTS) maglev vehicle system. In such a system, the HTS bulks were always exposed to AC external magnetic field, which was generated by the inhomogeneous surface magnetic field of the NdFeB guideway. In our previous work, it was observed that the guidance force of the YBCO bulk over the NdFeB guideway used in the HTS maglev vehicle system was decayed by the application of the AC external magnetic field. In this paper, we investigated the influence of the radius of the cylinder HTS bulk exposed to an AC magnetic field perturbation on the guidance force in the maglev vehicle system. From the results, it was found that the guidance force was stronger for the bulk with bigger radius and the guidance force decay rates of the bulks were approximately equal despite of the different radius in the maglev vehicle system. Therefore, in order to obtain higher guidance force in the maglev vehicle system, we could use the cylinder HTS bulks with the bigger radius.

Kinematics of anterior cruciate ligament-deficient knees in a Chinese population during stair ascent.

PubMed

Zhao, Chang; Lin, Chuangxin; Wang, Wenhao; Zeng, Chun; Fang, Hang; Pan, Jianying; Cai, Daozhang

2016-08-08

The purpose of this study was to measure the tibiofemoral kinematics of anterior cruciate ligament (ACL) deficiency in a Chinese population and compare the kinematics with published data about a Caucasian population. Unilateral knees of 18 Chinese ACL-deficient (ACL-D) subjects were studied while subjects ascended stairs. Kinematic alteration was compared between ACL-D knees and contralateral ACL-intact (ACL-I) knees. The kinematic alteration of ACL deficiency was also compared between the Chinese population and published data about a Caucasian population. A statistical difference was found in the three-dimensional rotations between ACL-D and ACL-I knees. In the sagittal plane, ACL-I knees had a larger flexion angle than ACL-D knees during 40 to 50 % of the activity during stair ascent (P < 0.027) and throughout the gait cycle. A significant difference in rotational motion between ACL-D and ACL-I knees was also observed in the frontal plane during 40 to 60 % (P < 0.017) of the activity and in the transverse plane during 70 to 80 % (P < 0.028) of the activity. A greater tibial varus was demonstrated in the Chinese population while the published data revealed external tibial rotation and a statistical difference in translation in the Caucasian population. ACL-D knees show different kinematics than ACL-I knees in the Chinese population. ACL-I knees had a larger flexion angle than ACL-D knees in the middle stage of the activity during stair ascent. A significant difference in rotational motion between ACL-D and ACL-I knees was also observed in the frontal plane during the middle phase and in the transverse plane during the terminal phase of the activity. A greater tibial varus was demonstrated in the Caucasian population while the published data revealed external tibial rotation and a statistical difference in translation in the Caucasian population.

Failure of Colorectal Surgical Site Infection Predictive Models Applied to an Independent Dataset: Do They Add Value or Just Confusion?

PubMed

Bergquist, John R; Thiels, Cornelius A; Etzioni, David A; Habermann, Elizabeth B; Cima, Robert R

2016-04-01

Colorectal surgical site infections (C-SSIs) are a major source of postoperative morbidity. Institutional C-SSI rates are modeled and scrutinized, and there is increasing movement in the direction of public reporting. External validation of C-SSI risk prediction models is lacking. Factors governing C-SSI occurrence are complicated and multifactorial. We hypothesized that existing C-SSI prediction models have limited ability to accurately predict C-SSI in independent data. Colorectal resections identified from our institutional ACS-NSQIP dataset (2006 to 2014) were reviewed. The primary outcome was any C-SSI according to the ACS-NSQIP definition. Emergency cases were excluded. Published C-SSI risk scores: the National Nosocomial Infection Surveillance (NNIS), Contamination, Obesity, Laparotomy, and American Society of Anesthesiologists (ASA) class (COLA), Preventie Ziekenhuisinfecties door Surveillance (PREZIES), and NSQIP-based models were compared with receiver operating characteristic (ROC) analysis to evaluate discriminatory quality. There were 2,376 cases included, with an overall C-SSI rate of 9% (213 cases). None of the models produced reliable and high quality C-SSI predictions. For any C-SSI, the NNIS c-index was 0.57 vs 0.61 for COLA, 0.58 for PREZIES, and 0.62 for NSQIP: all well below the minimum "reasonably" predictive c-index of 0.7. Predictions for superficial, deep, and organ space SSI were similarly poor. Published C-SSI risk prediction models do not accurately predict C-SSI in our independent institutional dataset. Application of externally developed prediction models to any individual practice must be validated or modified to account for institution and case-mix specific factors. This questions the validity of using externally or nationally developed models for "expected" outcomes and interhospital comparisons. Copyright © 2016 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Boosted Hyperthermia Therapy by Combined AC Magnetic and Photothermal Exposures in Ag/Fe3O4 Nanoflowers.

PubMed

Das, R; Rinaldi-Montes, N; Alonso, J; Amghouz, Z; Garaio, E; García, J A; Gorria, P; Blanco, J A; Phan, M H; Srikanth, H

2016-09-28

Over the past two decades, magnetic hyperthermia and photothermal therapy are becoming very promising supplementary techniques to well-established cancer treatments such as radiotherapy and chemotherapy. These techniques have dramatically improved their ability to perform controlled treatments, relying on the procedure of delivering nanoscale objects into targeted tumor tissues, which can release therapeutic killing doses of heat either upon AC magnetic field exposure or laser irradiation. Although an intense research effort has been made in recent years to study, separately, magnetic hyperthermia using iron oxide nanoparticles and photothermal therapy based on gold or silver plasmonic nanostructures, the full potential of combining both techniques has not yet been systematically explored. Here we present a proof-of-principle experiment showing that designing multifunctional silver/magnetite (Ag/Fe3O4) nanoflowers acting as dual hyperthermia agents is an efficient route for enhancing their heating ability or specific absorption rate (SAR). Interestingly, the SAR of the nanoflowers is increased by at least 1 order of magnitude under the application of both an external magnetic field of 200 Oe and simultaneous laser irradiation. Furthermore, our results show that the synergistic exploitation of the magnetic and photothermal properties of the nanoflowers reduces the magnetic field and laser intensities that would be required in the case that both external stimuli were applied separately. This constitutes a key step toward optimizing the hyperthermia therapy through a combined multifunctional magnetic and photothermal treatment and improving our understanding of the therapeutic process to specific applications that will entail coordinated efforts in physics, engineering, biology, and medicine.

Investigation of the transition of multicycle AC operation in ISTTOK under edge electrode biasing

NASA Astrophysics Data System (ADS)

Malaquias, A.; Henriques, R. B.; Silva, C.; Figueiredo, H.; Nedzelskiy, I. S.; Fernandes, H.; Sharma, R.; Plyusnin, V. V.

2017-11-01

In this paper we present recent results obtained on plasma edge electrode biasing during AC discharges. The goal is to obtain experimental evidence on a number of plasma parameters that can play a role during the AC transition on the repeatability and reproducibility of AC operation. The control of the plasma density in the quiescent phase is made just before the AC transition by means of positive edge biasing leading to a transitory improved of density (30%-40%). Gas puff experiments show that the increase of background gas pressure during discharge led to a better success of the AC transition. The experimental results indicate that the increase of density during the AC transition induced by edge biasing is followed by an electron temperature drop. The drop in electron temperature leads in most cases the formation of runaway electrons. It has been observed that the runaway population during discharge flattop depends on the interplay between gas content and plasma density and temperature. The results also confirm that the correct balance of external magnetic fields is crucial during the AC transition phase where drift electron currents are formed. The results from the heavy ion beam diagnostic show that the formation of plasma current during consecutive AC transitions is asymmetric. Numerical simulations indicate that for some particular conditions this result could be reproduced from assuming the presence of two counter-currents during AC transition.

Stability of the electroosmotic flow of a two-layer electrolyte-dielectric system with external pressure gradient⋆.

PubMed

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

2018-03-27

The stability of the electroosmotic flow of electrolyte-dielectric viscous liquids under the influence of the DC and AC electric fields along with the external pressure gradient is studied theoretically. Liquids are bounded by two infinite parallel plates. The lower wall bordering the electrolyte is assumed to be a charged surface, and the upper wall is electrically isolated. The charge at the lower boundary is assumed to be immobile, while the surface charge at the free surface is assumed to be mobile. In this paper, we study the micro- and nanosized liquid layers. The mathematical model is described by a nonlinear system of the Nernst-Planck-Poisson-Stokes partial differential equations with the appropriate boundary conditions on the solid surface, the electrolyte/dielectric interface, and on the upper wall. The pressure gradient is highly important for the stability of the flow. For the DC case, the external pressure could either stabilize and destabilize the flow depending on the relative directions of the electroosmotic flow and the pressure-driven flow. For the AC case, the dependence on the value of the external pressure is not monotonous for different wave numbers of perturbations, but, as a rule, the external pressure destabilizes the flow. As the frequency of the electric field increases, the one-dimensional solution of the problem becomes stable.

Instantaneous velocity measurement of AC electroosmotic flows by laser induced fluorescence photobleaching anemometer with high temporal resolution

NASA Astrophysics Data System (ADS)

Zhao, Wei; Yang, Fang; Qiao, Rui; Wang, Guiren; Rui Qiao Collaboration

2015-11-01

Understanding the instantaneous response of flows to applied AC electric fields may help understand some unsolved issues in induced-charge electrokinetics and enhance performance of microfluidic devices. Since currently available velocimeters have difficulty in measuring velocity fluctuations with frequency higher than 1 kHz, most experimental studies so far focus only on the average velocity measurement in AC electrokinetic flows. Here, we present measurements of AC electroosmotic flow (AC-EOF) response time in microchannels by a novel velocimeter with submicrometer spatial resolution and microsecond temporal resolution, i.e. laser-induced fluorescence photobleaching anemometer (LIFPA). Several parameters affecting the AC-EOF response time to the applied electric signal were investigated, i.e. channel length, transverse position and solution conductivity. The experimental results show that the EOF response time under a pulsed electric field decreases with the reduction of the microchannel length, distance between the detection position to the wall and the conductivity of the solution. This work could provide a new powerful tool to measure AC electrokinetics and enhance our understanding of AC electrokinetic flows.

Tadpole-shaped lateralized parietal atretic cephalocele associated with an ipsilateral lacrimal gland fistula and schizencephalic clefts.

PubMed

Murakami, Nobuya; Morioka, Takato; Suzuki, Satoshi O; Mukae, Nobutaka; Hashiguchi, Kimiaki; Iihara, Koji

2017-02-01

Parietal atretic cephalocele (AC) and its associated intracranial venous anomalies, such as vertical embryonic positioning of the straight sinus (VEP of SS), have, in previous reports, been exclusively restricted to the midline. We report a patient with lateralized parietal AC on the right side. The AC was in the shape of a tadpole, with a large head and a long tail, extending to the proximity of the right external canthus, where a lacrimal gland fistula was observed. The superior sagittal sinus and VEP of SS were also displaced to the right side, although the sagittal suture was located at the midline. Schizencephalic clefts in the right posterior cortex were also observed. The parietal AC, which was initially located in the midline, could conceivably have been displaced to the right side by other developmental processes. However, the relationship between lateralized AC and associated multiple anomalies on the ipsilateral side is difficult to explain monogenetically. Our case study indicates that AC might have a broader spectrum of clinical symptoms than was once thought to be the case.

Coincidence of features of emitted THz electromagnetic wave power form a single Josephson junction and different current components

NASA Astrophysics Data System (ADS)

Hamdipour, Mohammad

2017-12-01

By applying a voltage to a Josephson junction, the charge in superconducting layers (S-layers) will oscillate. Wavelength of the charge oscillations in S-layers is related to external current in junction, by increasing the external current, the wavelength will decrease which cause in some currents the wavelength be incommensurate with width of junction, so the CVC shows Fiske like steps. External current throwing along junction has some components, resistive, capacitive and superconducting current, beside these currents there is a current in lateral direction of junction, (x direction). On the other hand, the emitted electromagnetic wave power in THz region is related to AC component of electric field in junction, which itself is related to charge density in S-layers, which is related to currents in the system. So we expect that features of variation of current components reflect the features of emitted THz power form junction. Here we study in detail the superconductive current in a long Josephson junction (JJ), the current voltage characteristics (CVC) of junction and emitted THz power from the system. Then we compare the results. Comparing the results we see that there is a good qualitative coincidence in features of emitted THz power and supercurrent in junction.

Consumption of the electric power inside silent discharge reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yehia, Ashraf, E-mail: yehia30161@yahoo.com

An experimental study was made in this paper to investigate the relation between the places of the dielectric barriers, which cover the surfaces of the electrodes in the coaxial cylindrical reactors, and the rate of change of the electric power that is consumed in forming silent discharges. Therefore, silent discharges have been formed inside three coaxial cylindrical reactors. The dielectric barriers in these reactors were pasted on both the internal surface of the outer electrode in the first reactor and the external surface of the inner electrode in the second reactor as well as the surfaces of the two electrodesmore » in the third reactor. The reactor under study has been fed by atmospheric air that flowed inside it with a constant rate at normal temperature and pressure, in parallel with the application of a sinusoidal ac voltage between the electrodes of the reactor. The electric power consumed in forming the silent discharges inside the three reactors was measured as a function of the ac peak voltage. The validity of the experimental results was investigated by applying Manley's equation on the same discharge conditions. The results have shown that the rate of consumption of the electric power relative to the ac peak voltage per unit width of the discharge gap improves by a ratio of either 26.8% or 80% or 128% depending on the places of the dielectric barriers that cover the surfaces of the electrodes inside the three reactors.« less

Deriving physical parameters of unresolved star clusters. V. M 31 PHAT star clusters

NASA Astrophysics Data System (ADS)

de Meulenaer, P.; Stonkutė, R.; Vansevičius, V.

2017-06-01

Context. This study is the fifth of a series that investigates the degeneracy and stochasticity problems present in the determination of physical parameters such as age, mass, extinction, and metallicity of partially resolved or unresolved star cluster populations in external galaxies when using HST broad-band photometry. Aims: In this work we aim to derive parameters of star clusters using models with fixed and free metallicity based on the HST WFC3+ACS photometric system. The method is applied to derive parameters of a subsample of 1363 star clusters in the Andromeda galaxy observed with the HST. Methods: Following Paper III, we derive the star cluster parameters using a large grid of stochastic models that are compared to the six observed integrated broad-band WFC3+ACS magnitudes of star clusters. Results: We show that the age, mass, and extinction of the M 31 star clusters, derived assuming fixed solar metallicity, are in agreement with previous studies. We also demonstrate the ability of the WFC3+ACS photometric system to derive metallicity of star clusters older than 1 Gyr. We show that the metallicity derived using broad-band photometry of 36 massive M 31 star clusters is in good agreement with the metallicity derived using spectroscopy. Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/602/A112

Frequency-dependent tACS modulation of BOLD signal during rhythmic visual stimulation.

PubMed

Chai, Yuhui; Sheng, Jingwei; Bandettini, Peter A; Gao, Jia-Hong

2018-05-01

Transcranial alternating current stimulation (tACS) has emerged as a promising tool for modulating cortical oscillations. In previous electroencephalogram (EEG) studies, tACS has been found to modulate brain oscillatory activity in a frequency-specific manner. However, the spatial distribution and hemodynamic response for this modulation remains poorly understood. Functional magnetic resonance imaging (fMRI) has the advantage of measuring neuronal activity in regions not only below the tACS electrodes but also across the whole brain with high spatial resolution. Here, we measured fMRI signal while applying tACS to modulate rhythmic visual activity. During fMRI acquisition, tACS at different frequencies (4, 8, 16, and 32 Hz) was applied along with visual flicker stimulation at 8 and 16 Hz. We analyzed the blood-oxygen-level-dependent (BOLD) signal difference between tACS-ON vs tACS-OFF, and different frequency combinations (e.g., 4 Hz tACS, 8 Hz flicker vs 8 Hz tACS, 8 Hz flicker). We observed significant tACS modulation effects on BOLD responses when the tACS frequency matched the visual flicker frequency or the second harmonic frequency. The main effects were predominantly seen in regions that were activated by the visual task and targeted by the tACS current distribution. These findings bridge different scientific domains of tACS research and demonstrate that fMRI could localize the tACS effect on stimulus-induced brain rhythms, which could lead to a new approach for understanding the high-level cognitive process shaped by the ongoing oscillatory signal. © 2018 Wiley Periodicals, Inc.

Field-effect transistor improves electrometer amplifier

NASA Technical Reports Server (NTRS)

Munoz, R.

1964-01-01

An electrometer amplifier uses a field effect transistor to measure currents of low amperage. The circuit, developed as an ac amplifier, is used with an external filter which limits bandwidth to achieve optimum noise performance.

The design and construction of a module to demonstrate a method for transmission of data from a medical implant

NASA Astrophysics Data System (ADS)

Morgan, I.; Benjamin, J. D.

1985-08-01

Methods of powering devices to which only ac contact can be made and receiving data transmitted back from them are described. Such devices include medical implants which communicate with the external environment via ultrasound or rf links. Two breadboard systems were built to demonstrate the techniques. In both the device is powered by picking up an ac input and rectifying it. A signal voltage detected by the device is encoded as a frequency, transmitted and decoded. In one case this is performed on a separate channel from that used to power the device. In the other only one channel is used for both signals, and data is transmitted by modulating the impedance presented by the device. The resulting modulation of the input signal is picked up by the external circuit and decoded.

Ion trajectory simulations of axial ac dipolar excitation in the Orbitrap

NASA Astrophysics Data System (ADS)

Wu, Guangxiang; Noll, Robert J.; Plass, Wolfgang R.; Hu, Qizhi; Perry, Richard H.; Cooks, R. Graham

2006-07-01

The newly developed version of the multi-particle ion trajectory simulation program, ITSIM 6.0, was applied to simulate ac dipolar excitation of ion axial motion in the Orbitrap. The Orbitrap inner and outer electrodes were generated in AutoCAD, a 3D drawing program. The electrode geometry was imported into the 3D field solver COMSOL; the field array was then imported into ITSIM 6.0. Ion trajectories were calculated by solving Newton's equations using Runge-Kutta integration methods. Compared to the analytical solution, calculated radial components of the field at the device's "equator" (z = 0) were within 0.5% and calculated axial components midway between the inner and outer electrodes were within 0.2%. The experiments simulated here involved the control of axial motion of ions in the Orbitrap by the application of dipolar ac signals to the split outer electrodes, as described in a recently published paper from this laboratory [Hu et al., J. Phys. Chem. A 110 (2006) 2682]. In these experiments, ac signal was applied at the axial resonant frequency of a selected ion. Axial excitation and eventual ion ejection resulted when the ac was in phase with, i.e., had 0° phase relative to ion axial motion. De-excitation of ion axial motion until the ions were at z = 0 and at rest with respect to the z-axis resulted if the applied ac was out of phase with ion motion, with re-excitation of ion axial motion occurring if the dipolar ac was continued beyond this point. Both de-excitation and re-excitation could be achieved mass-selectively and depended on the amplitude and duration (number of cycles) of the applied ac. The effects of ac amplitude, frequency, phase relative to ion motion, and bandwidth of applied waveform were simulated. All simulation results were compared directly with the experimental data and good agreement was observed. Such ion motion control experiments and their simulation provide the possibility to improve Orbitrap performance and to develop tandem mass spectrometry (MS/MS) capabilities inside the Orbitrap.

Development of external cooling cryo-resistive cable systems. Part 2: Insulation characteristics on 66 kV rated cryo-resistive testing cable

NASA Astrophysics Data System (ADS)

Ishihara, Kaoru; Akita, Shige; Suzuki, Hiroshi; Ogata, Junichi; Nemoto, Minoru

1987-08-01

Cryo-resistive cable system was tested to demonstrate dielectric characteristics. Dielectric characteristics of 66kV cryo-resistive cable at the start of immersion cooling in the liquid nitrogen were 2.25 specific dielectric constant and 0.18 percent dielectric loss which was less than 0.4 percent , the aimed value. Electrostatic capacity and dielectric loss tangent of dielectric characteristics under the applied voltage did not depend on the voltage and the dielectric loss was less than 0.4 percent through the temperature range from -170 to -190C. These values fulfilled the specifications on 275kV class cryo-resistive cable design. The tested cable passed the cable test on 66kV oil-filled cable (ac 90kV, 10 min), but broken down at ac 110kV on the way to endurance testing voltage 130kV. The breakdown occurred due to the mechanical damage of cable insulator by bending and thermal contraction of the cable. It is necessary from these facts to develop flexible cable terminal and joint which can absorb the contraction to realize 275kV cryo-resistive cable. (19 figs, 7 tabs, 15 refs).

On the magnetism of the C14 Nb0.975Fe2.025 Laves phase compound: Determination of the H-T phase diagram

NASA Astrophysics Data System (ADS)

Bałanda, Maria; Dubiel, Stanisław M.

2018-05-01

A C14 Nb0.975Fe2.025 Laves phase compound was investigated aimed at determining the H-T magnetic phase diagram. Magnetization, M, and AC magnetic susceptibility measurement were performed. Concerning the former field-cooled and zero-field-cooled M-curves were recorded in the temperature range of 2-200 K and in applied magnetic field, H, up to 1000 Oe, isothermal M(H) curves at 2 K, 5 K, 50 K, 80 K and 110 K as well as hysteresis loops at several temperatures over the field range of ±10 kOe were measured. Regarding the AC susceptibility, χ, both real and imaginary components were registered as a function of increasing temperature in the interval of 2 K-150 K at the frequencies of the oscillating field, f, from 3 Hz up to 999 Hz. An influence of the external DC magnetic field on the temperature dependence of χ was investigated, too. The measurements clearly demonstrated that the magnetism of the studied sample is weak, itinerant and has a reentrant character. Based on the obtained results a magnetic phase diagram has been constructed in the H-T coordinates.

Skyrmions Driven by Intrinsic Magnons

NASA Astrophysics Data System (ADS)

Psaroudaki, Christina; Loss, Daniel

2018-06-01

We study the dynamics of a Skyrmion in a magnetic insulating nanowire in the presence of time-dependent oscillating magnetic field gradients. These ac fields act as a net driving force on the Skyrmion via its own intrinsic magnetic excitations. In a microscopic quantum field theory approach, we include the unavoidable coupling of the external field to the magnons, which gives rise to time-dependent dissipation for the Skyrmion. We demonstrate that the magnetic ac field induces a super-Ohmic to Ohmic crossover behavior for the Skyrmion dissipation kernels with time-dependent Ohmic terms. The ac driving of the magnon bath at resonance results in a unidirectional helical propagation of the Skyrmion in addition to the otherwise periodic bounded motion.

Faradaic AC Electrokinetic Flow and Particle Traps

NASA Astrophysics Data System (ADS)

Ben, Yuxing; Chang, Hsueh-Chia

2004-11-01

Faradaic reaction at higher voltages can produce co-ion polarization at AC electrodes instead of counter-ion polarization due to capacitive charging from the bulk. The Faradaic co-ion polarization also does not screen the external field and hence can produce large net electro-kinetic flows at frequencies lower than the inverse RC time of the double layer. Due to the opposite polarization of capacitve and Faradaic charging, we can reverse the direction of AC flows on electrodes by changing the voltage and frequency. Particles and bacteria are trapped and then dispersed at stagnation lines, at locations predicted by our theory, by using these two flows sequentially. This technique offers a good way to concentrate and detect bacteria.

Rectilinear accelerometer possesses self- calibration feature

NASA Technical Reports Server (NTRS)

Henderson, R. B.

1966-01-01

Rectilinear accelerometer operates from an ac source with a phase-sensitive ac voltage output proportional to the applied accelerations. The unit includes an independent circuit for self-test which provides a sensor output simulating an acceleration applied to the sensitive axis of the accelerometer.

The Dynamics of Oblate Drop Between Heterogeneous Plates Under Alternating Electric Field. Non-uniform Field

NASA Astrophysics Data System (ADS)

Kashina, M. A.; Alabuzhev, A. A.

2018-02-01

The dynamics of the incompressible fluid drop under the non-uniform electric field are considered. The drop is bounded axially by two parallel solid planes and the case of heterogeneous plates is investigated. The external electric field acts as an external force that causes motion of the contact line. We assume that the electric current is alternative current and the AC filed amplitude is a spatially non-uniform function. In equilibrium, the drop has the form of a circular cylinder. The equilibrium contact angle is 0.5 π. In order to describe this contact line motion the modified Hocking boundary condition is applied: the velocity of the contact line is proportional to the deviation of the contact angle and the speed of the fast relaxation processes, which frequency is proportional to twice the frequency of the electric field. The Hocking parameter depends on the polar angle, i.e. the coefficient of the interaction between the plate and the fluid (the contact line) is a function of the plane coordinates. This function is expanded in a series of the Laplace operator eigenfunctions.

Effect of an ac Perturbation on the Electroosmotic Behavior of a Cation-Exchange Membrane. Influence of the Cation Nature.

PubMed

Barragán, V. M.; Bauzá, C. Ruíz

2001-08-01

The effect of an ac sinusoidal perturbation of known amplitude and frequency superimposed on the usual dc applied electric voltage difference on the electroosmotic flow through a typical cation-exchange membrane has been studied using different monovalent electrolytes. As a general trend, the presence of the ac perturbation increases the value of the electroosmotic flow with respect to the value in the absence of ac perturbation. A dispersion of the electroosmotic permeability on the frequency of the applied ac signal has been found for the three studied electrolytes, observing that the electroosmotic permeability reaches maximum values for some characteristic values of the frequency. This behavior may be related to the different relaxation processes in heterogeneous mediums. Copyright 2001 Academic Press.

A user-friendly risk-score for predicting in-hospital cardiac arrest among patients admitted with suspected non ST-elevation acute coronary syndrome - The SAFER-score.

PubMed

Faxén, Jonas; Hall, Marlous; Gale, Chris P; Sundström, Johan; Lindahl, Bertil; Jernberg, Tomas; Szummer, Karolina

2017-12-01

To develop a simple risk-score model for predicting in-hospital cardiac arrest (CA) among patients hospitalized with suspected non-ST elevation acute coronary syndrome (NSTE-ACS). Using the Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies (SWEDEHEART), we identified patients (n=242 303) admitted with suspected NSTE-ACS between 2008 and 2014. Logistic regression was used to assess the association between 26 candidate variables and in-hospital CA. A risk-score model was developed and validated using a temporal cohort (n=126 073) comprising patients from SWEDEHEART between 2005 and 2007 and an external cohort (n=276 109) comprising patients from the Myocardial Ischaemia National Audit Project (MINAP) between 2008 and 2013. The incidence of in-hospital CA for NSTE-ACS and non-ACS was lower in the SWEDEHEART-derivation cohort than in MINAP (1.3% and 0.5% vs. 2.3% and 2.3%). A seven point, five variable risk score (age ≥60 years (1 point), ST-T abnormalities (2 points), Killip Class >1 (1 point), heart rate <50 or ≥100bpm (1 point), and systolic blood pressure <100mmHg (2 points) was developed. Model discrimination was good in the derivation cohort (c-statistic 0.72) and temporal validation cohort (c-statistic 0.74), and calibration was reasonable with a tendency towards overestimation of risk with a higher sum of score points. External validation showed moderate discrimination (c-statistic 0.65) and calibration showed a general underestimation of predicted risk. A simple points score containing five variables readily available on admission predicts in-hospital CA for patients with suspected NSTE-ACS. Copyright © 2017 Elsevier B.V. All rights reserved.

Prefrontal Function Engaging in External-Focused Attention in 5- to 6-Month-Old Infants: A Suggestion for Default Mode Network.

PubMed

Xu, Mingdi; Hoshino, Eiichi; Yatabe, Kiyomi; Matsuda, Soichiro; Sato, Hiroki; Maki, Atsushi; Yoshimura, Mina; Minagawa, Yasuyo

2016-01-01

The present study used functional near-infrared spectroscopy (fNIRS) to measure 5- to 6-month-old infants' hemodynamic response in the prefrontal cortex (PFC) to visual stimuli differing in saliency and social value. Nineteen Japanese 5- to 6-month-old infants watched video clips of Peek-a-Boo (social signal) performed by an anime character (AC) or a human, and hand movements without social signal performed by an AC. The PFC activity of infants was measured by 22-channel fNIRS, while behaviors including looking time were recorded simultaneously. NIRS data showed that infants' hemodynamic responses in the PFC generally decreased due to these stimuli, and the decrease was most prominent in the frontopolar (FP), covering medial PFC (MPFC), when infants were viewing Peek-a-Boo performed by an AC. Moreover, the decrease was more pronounced in the dorsolateral PFC (DLPFC) when infants were viewing Peek-a-Boo performed by an AC than by a human. Accordingly, behavioral data revealed significantly longer looking times when Peek-a-Boo was performed by an AC than by a human. No significant difference between Peek-a-Boo and non-Peek-a-Boo conditions was observed in either measure. These findings indicate that infants at this age may prefer stimuli with more salient features, which may be more effective in attracting their attentions. In conjunction with our previous findings on responses to self-name calling in infants of similar age, we hypothesize that the dynamic function of the MPFC and its vicinity (as part of default mode network (DMN): enhanced by self-focused stimuli, attenuated by externally focused stimuli), which is consistently observed in adults, may have already emerged in 5- to 6-month-old infants.

Prefrontal Function Engaging in External-Focused Attention in 5- to 6-Month-Old Infants: A Suggestion for Default Mode Network

PubMed Central

Xu, Mingdi; Hoshino, Eiichi; Yatabe, Kiyomi; Matsuda, Soichiro; Sato, Hiroki; Maki, Atsushi; Yoshimura, Mina; Minagawa, Yasuyo

2017-01-01

The present study used functional near-infrared spectroscopy (fNIRS) to measure 5- to 6-month-old infants’ hemodynamic response in the prefrontal cortex (PFC) to visual stimuli differing in saliency and social value. Nineteen Japanese 5- to 6-month-old infants watched video clips of Peek-a-Boo (social signal) performed by an anime character (AC) or a human, and hand movements without social signal performed by an AC. The PFC activity of infants was measured by 22-channel fNIRS, while behaviors including looking time were recorded simultaneously. NIRS data showed that infants’ hemodynamic responses in the PFC generally decreased due to these stimuli, and the decrease was most prominent in the frontopolar (FP), covering medial PFC (MPFC), when infants were viewing Peek-a-Boo performed by an AC. Moreover, the decrease was more pronounced in the dorsolateral PFC (DLPFC) when infants were viewing Peek-a-Boo performed by an AC than by a human. Accordingly, behavioral data revealed significantly longer looking times when Peek-a-Boo was performed by an AC than by a human. No significant difference between Peek-a-Boo and non-Peek-a-Boo conditions was observed in either measure. These findings indicate that infants at this age may prefer stimuli with more salient features, which may be more effective in attracting their attentions. In conjunction with our previous findings on responses to self-name calling in infants of similar age, we hypothesize that the dynamic function of the MPFC and its vicinity (as part of default mode network (DMN): enhanced by self-focused stimuli, attenuated by externally focused stimuli), which is consistently observed in adults, may have already emerged in 5- to 6-month-old infants. PMID:28119586

Fibrillar disruption by AC electric field induced oscillation: A case study with human serum albumin.

PubMed

Sen, Shubhatam; Chakraborty, Monojit; Goley, Snigdha; Dasgupta, Swagata; DasGupta, Sunando

2017-07-01

The effect of oscillation induced by a frequency-dependent alternating current (AC) electric field to dissociate preformed amyloid fibrils has been investigated. An electrowetting-on-dielectric type setup has been used to apply the AC field of varying frequencies on preformed fibrils of human serum albumin (HSA). The disintegration potency has been monitored by a combination of spectroscopic and microscopic techniques. The experimental results suggest that the frequency of the applied AC field plays a crucial role in the disruption of preformed HSA fibrils. The extent of stress generated inside the droplet due to the application of the AC field at different frequencies has been monitored as a function of the input frequency of the applied AC voltage. This has been accomplished by assessing the morphology deformation of the oscillating HSA fibril droplets. The shape deformation of the oscillating droplets is characterized using image analysis by measuring the dynamic changes in the shape dependent parameters such as contact angle and droplet footprint radius and the amplitude. It is suggested that the cumulative effects of the stress generated inside the HSA fibril droplets due to the shape deformation induced hydrodynamic flows and the torque induced by the intrinsic electric dipoles of protein due to their continuous periodic realignment in presence of the AC electric field results in the destruction of the fibrillar species. Copyright © 2017. Published by Elsevier B.V.

Lateral separation of colloids or cells by dielectrophoresis augmented by AC electroosmosis.

PubMed

Zhou, Hao; White, Lee R; Tilton, Robert D

2005-05-01

Colloidal particles and biological cells are patterned and separated laterally adjacent to a micropatterned electrode array by applying AC electric fields that are principally oriented normally to the electrode array. This is demonstrated for yeast cells, red blood cells, and colloidal polystyrene particles of different sizes and zeta-potentials. The separation mechanism is observed experimentally to depend on the applied field frequency and voltage. At high frequencies, particles position themselves in a manner that is consistent with dielectrophoresis, while at low frequencies, the positioning is explained in terms of a strong coupling between gravity, the vertical component of the dielectrophoretic force, and the Stokes drag on particles induced by AC electroosmotic flow. Compared to high frequency dielectrophoretic separations, the low frequency separations are faster and require lower applied voltages. Furthermore, the AC electroosmosis coupling with dielectrophoresis may enable cell separations that are not feasible based on dielectrophoresis alone.

High-Performance AC Power Source by Applying Robust Stability Control Technology for Precision Material Machining

NASA Astrophysics Data System (ADS)

Chang, En-Chih

2018-02-01

This paper presents a high-performance AC power source by applying robust stability control technology for precision material machining (PMM). The proposed technology associates the benefits of finite-time convergent sliding function (FTCSF) and firefly optimization algorithm (FOA). The FTCSF maintains the robustness of conventional sliding mode, and simultaneously speeds up the convergence speed of the system state. Unfortunately, when a highly nonlinear loading is applied, the chatter will occur. The chatter results in high total harmonic distortion (THD) output voltage of AC power source, and even deteriorates the stability of PMM. The FOA is therefore used to remove the chatter, and the FTCSF still preserves finite system-state convergence time. By combining FTCSF with FOA, the AC power source of PMM can yield good steady-state and transient performance. Experimental results are performed in support of the proposed technology.

(1) Majorana fermions in pinned vortices; (2) Manipulating and probing Majorana fermions using superconducting circuits; and (3) Controlling a nanowire spin-orbit qubit via electric-dipole spin resonance

NASA Astrophysics Data System (ADS)

Nori, Franco

2014-03-01

We study a heterostructure which consists of a topological insulator and a superconductor with a hole. This system supports a robust Majorana fermion state bound to the vortex core. We study the possibility of using scanning tunneling spectroscopy (i) to detect the Majorana fermion in this setup and (ii) to study excited states bound to the vortex core. The Majorana fermion manifests itself as an H-dependent zero-bias anomaly of the tunneling conductance. The excited states spectrum differs from the spectrum of a typical Abrikosov vortex, providing additional indirect confirmation of the Majorana state observation. We also study how to manipulate and probe Majorana fermions using super-conducting circuits. In we consider a semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC), which can be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the spin-orbit qubit can respond to an external ac electric field, i.e., electric-dipole spin resonance. We develop a theory that can apply in the strong SOC regime. We find that there is an optimal SOC strength ηopt = √ 2/2, where the Rabi frequency induced by the ac electric field becomes maximal. Also, we show that both the level spacing and the Rabi frequency of the spin-orbit qubit have periodic responses to the direction of the external static magnetic field. These responses can be used to determine the SOC in the nanowire. FN is partly supported by the RIKEN CEMS, iTHES Project, MURI Center for Dynamic Magneto-Optics, JSPS-RFBR Contract No. 12-02-92100, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics, and the JSPS via its FIRST program.

Dynamic characteristics of corona discharge generated under rainfall condition on AC charged conductors

NASA Astrophysics Data System (ADS)

Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

2017-12-01

By synchronous measurement of corona current and the water droplet deformation process on a conductor surface, different types of corona discharge are visualized when AC voltage is applied on a line-ground electrode system. The corona characteristics are closely related to the applied voltage and water supply rate. With the increase of AC voltage, the positive Taylor cone discharge firstly appears and then disappears, replaced by the dripping and crashing discharge. Furthermore, the number of pulses in each pulse train increases with the increase of applied voltage. The mechanism of the transfer from the positive Taylor cone discharge to the dripping and crashing discharge is found to be related to the oscillation process of the water droplet. The water supply rate also has a great influence on the characteristics of corona currents. The number of positive pulse trains increases linearly when the water supply rate gets larger, leading to a higher audible noise and radio interference level from the AC corona, which is quite different from that of the DC corona. The difference between the AC and DC coronas under rainfall conditions is analyzed finally.

Onboard power line conditioning system for an electric or hybrid vehicle

DOEpatents

Kajouke, Lateef A.; Perisic, Milun

2016-06-14

A power line quality conditioning system for a vehicle includes an onboard rechargeable direct current (DC) energy storage system and an onboard electrical system coupled to the energy storage system. The energy storage system provides DC energy to drive an electric traction motor of the vehicle. The electrical system operates in a charging mode such that alternating current (AC) energy from a power grid external to the vehicle is converted to DC energy to charge the DC energy storage system. The electrical system also operates in a vehicle-to-grid power conditioning mode such that DC energy from the DC energy storage system is converted to AC energy to condition an AC voltage of the power grid.

Effects of bio-functionalizing surface treatments on the mechanical behavior of open porous titanium biomaterials.

PubMed

Amin Yavari, S; Ahmadi, S M; van der Stok, J; Wauthle, R; Riemslag, A C; Janssen, M; Schrooten, J; Weinans, H; Zadpoor, A A

2014-08-01

Bio-functionalizing surface treatments are often applied for improving the bioactivity of biomaterials that are based on otherwise bioinert titanium alloys. When applied on highly porous titanium alloy structures intended for orthopedic bone regeneration purposes, such surface treatments could significantly change the static and fatigue properties of these structures and, thus, affect the application of the biomaterial as bone substitute. Therefore, the interplay between biofunctionalizing surface treatments and mechanical behavior needs to be controlled. In this paper, we studied the effects of two bio-functionalizing surface treatments, namely alkali-acid heat treatment (AlAcH) and acid-alkali (AcAl), on the static and fatigue properties of three different highly porous titanium alloy implants manufactured using selective laser melting. It was found that AlAcH treatment results in minimal mass loss. The static and fatigue properties of AlAcH specimens were therefore not much different from as-manufactured (AsM) specimens. In contrast, AcAl resulted in substantial mass loss and also in significantly less static and fatigue properties particularly for porous structures with the highest porosity. The ratio of the static mechanical properties of AcAl specimens to that of AsM specimen was in the range of 1.5-6. The fatigue lives of AcAl specimens were much more severely affected by the applied surface treatments with fatigue lives up to 23 times smaller than that of AsM specimens particularly for the porous structures with the highest porosity. In conclusion, the fatigue properties of surface treated porous titanium are dependent not only on the type of applied surface treatment but also on the porosity of the biomaterial. Copyright © 2014 Elsevier Ltd. All rights reserved.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Characteristics of alternating current hopping conductivity in DNA sequences

NASA Astrophysics Data System (ADS)

Ma, Song-Shan; Xu, Hui; Wang, Huan-You; Guo, Rui

2009-08-01

This paper presents a model to describe alternating current (AC) conductivity of DNA sequences, in which DNA is considered as a one-dimensional (1D) disordered system, and electrons transport via hopping between localized states. It finds that AC conductivity in DNA sequences increases as the frequency of the external electric field rises, and it takes the form of øac(ω) ~ ω2 ln2(1/ω). Also AC conductivity of DNA sequences increases with the increase of temperature, this phenomenon presents characteristics of weak temperature-dependence. Meanwhile, the AC conductivity in an off-diagonally correlated case is much larger than that in the uncorrelated case of the Anderson limit in low temperatures, which indicates that the off-diagonal correlations in DNA sequences have a great effect on the AC conductivity, while at high temperature the off-diagonal correlations no longer play a vital role in electric transport. In addition, the proportion of nucleotide pairs p also plays an important role in AC electron transport of DNA sequences. For p < 0.5, the conductivity of DNA sequence decreases with the increase of p, while for p >= 0.5, the conductivity increases with the increase of p.

Roebel assembled coated conductor cables (RACC): Ac-Losses and current carrying potential

NASA Astrophysics Data System (ADS)

Frank, A.; Heller, R.; Goldacker, W.; Kling, A.; Schmidt, C.

2008-02-01

Low ac-loss HTS cables for transport currents well above 1 kA are required for application in transformers and generators and are taken into consideration for future generations of fusion reactor coils. Coated conductors (CC) are suitable candidates for high field application at an operation temperature in the range 50-77 K. Ac-field applications require cables with low ac-losses and hence twisting of the individual strands. We solved this problem using the Roebel technique. Short lengths of Roebel bar cables were prepared from industrial DyBCO and YBCO-CC. Meander shaped tapes of 4 or 5 mm width with twist pitches of 123 or 127 mm were cut from the 10 or 12 mm wide CC tapes using a specially designed tool. Eleven or twelve of these strands were assembled to a cable. The electrical and mechanical connection of the tapes was achieved using a silver powder filled conductive epoxy resin. Ac-losses of a short sample in an external ac-field were measured as a function of frequency and field amplitude as well as the coupling current decay time constant. We discuss the results in terms of available theories and compare measured time constants in transverse field with measured coupling losses. Finally the potential of this cable type for ac-use is discussed with respect to ac-losses and current carrying capability.

Comparison of activated carbon and iron/cerium modified activated carbon to remove methylene blue from wastewater.

PubMed

Cheng, Song; Zhang, Libo; Ma, Aiyuan; Xia, Hongying; Peng, Jinhui; Li, Chunyang; Shu, Jianhua

2018-03-01

The methylene blue (MB) removal abilities of raw activated carbon and iron/cerium modified raw activated carbon (Fe-Ce-AC) by adsorption were researched and compared. The characteristics of Fe-Ce-AC were examined by N 2 adsorption, zeta potential measurement, FTIR, Raman, XRD, XPS, SEM and EDS. After modification, the following phenomena occurred: The BET surface area, average pore diameter and total pore volume decreased; the degree of graphitization also decreased. Moreover, the presence of Fe 3 O 4 led to Fe-Ce-AC having magnetic properties, which makes it easy to separate from dye wastewater in an external magnetic field and subsequently recycle. In addition, the equilibrium isotherms and kinetics of MB adsorption on raw activated carbon and Fe-Ce-AC were systematically examined. The equilibrium adsorption data indicated that the adsorption behavior followed the Langmuir isotherm, and the pseudo-second-order model matched the kinetic data well. Compared with raw activated carbon, the maximum monolayer adsorption capacity of Fe-Ce-AC increased by 27.31%. According to the experimental results, Fe-Ce-AC can be used as an effective adsorbent for the removal of MB from dye wastewater. Copyright © 2017. Published by Elsevier B.V.

Domain Wall Depinning in Random Media by ac Fields

NASA Astrophysics Data System (ADS)

Glatz, A.; Nattermann, T.; Pokrovsky, V.

2003-01-01

The viscous motion of an interface driven by an ac external field of frequency ω0 in a random medium is considered here in the nonadiabatic regime. The velocity exhibits a smeared depinning transition showing a double hysteresis which is absent in the adiabatic case ω0→0. Using scaling arguments and an approximate renormalization group calculation we explain the main characteristics of the hysteresis loop. In the low frequency limit these can be expressed in terms of the depinning threshold and the critical exponents of the adiabatic case.

Biomarker development for external CO2 injury prediction in apples through exploration of both transcriptome and DNA methylation changes

PubMed Central

Gapper, Nigel E.; Rudell, David R.; Giovannoni, James J.; Watkins, Chris B.

2013-01-01

Several apple cultivars are susceptible to CO2 injury, a physiological disorder that can be expressed either externally or internally, and which can cause major losses of fruit during controlled atmosphere (CA) storage. Disorder development can also be enhanced using SmartFresh™ technology, based on the inhibition of ethylene perception by 1-methylcyclopropene (1-MCP). Injury development is associated with less mature fruit with lower ethylene production, but the aetiology of the disorder is poorly understood. Here we report on the progress made using mRNAseq approaches to explore the transcriptome during the development of external CO2 injury. Next-generation sequencing was used to mine the apple transcriptome for gene expression changes that are associated with the development of external CO2 injury. ‘Empire’ apples from a single orchard were treated with either 1 µL L−1 1-MCP or 1 g L−1 diphenylamine or left untreated, and then stored in a CA of 5 kPa CO2 and 2 kPa O2. In addition, susceptibility to the disorder in the ‘Empire’ apples from five different orchards was investigated and the methylation state of the ACS1 promoter investigated using McrBC endonuclease digestion and real-time quantitative polymerase chain reaction. Expression of over 30 000 genes, aligned to the apple genome, was monitored, with clear divergence of expression among treatments after 1 day of CA storage. Symptom development, internal ethylene concentrations (IECs) and methylation state of the ACS1 promoter were different for each of five orchards. With transcriptomic changes affected by treatment, this dataset will be useful in discovering biomarkers that assess disorder susceptibility. An inverse correlation between the frequency of this disorder and the IEC was detected in a multiple orchard trial. Differential methylation state of the ACS1 promoter correlated with both IEC and injury occurrence, indicating epigenetic regulation of ethylene biosynthesis and possibly events leading to disorder development. PMID:23671787

Biomarker development for external CO2 injury prediction in apples through exploration of both transcriptome and DNA methylation changes.

PubMed

Gapper, Nigel E; Rudell, David R; Giovannoni, James J; Watkins, Chris B

2013-01-01

Several apple cultivars are susceptible to CO2 injury, a physiological disorder that can be expressed either externally or internally, and which can cause major losses of fruit during controlled atmosphere (CA) storage. Disorder development can also be enhanced using SmartFresh™ technology, based on the inhibition of ethylene perception by 1-methylcyclopropene (1-MCP). Injury development is associated with less mature fruit with lower ethylene production, but the aetiology of the disorder is poorly understood. Here we report on the progress made using mRNAseq approaches to explore the transcriptome during the development of external CO2 injury. Next-generation sequencing was used to mine the apple transcriptome for gene expression changes that are associated with the development of external CO2 injury. 'Empire' apples from a single orchard were treated with either 1 µL L(-1) 1-MCP or 1 g L(-1) diphenylamine or left untreated, and then stored in a CA of 5 kPa CO2 and 2 kPa O2. In addition, susceptibility to the disorder in the 'Empire' apples from five different orchards was investigated and the methylation state of the ACS1 promoter investigated using McrBC endonuclease digestion and real-time quantitative polymerase chain reaction. Expression of over 30 000 genes, aligned to the apple genome, was monitored, with clear divergence of expression among treatments after 1 day of CA storage. Symptom development, internal ethylene concentrations (IECs) and methylation state of the ACS1 promoter were different for each of five orchards. With transcriptomic changes affected by treatment, this dataset will be useful in discovering biomarkers that assess disorder susceptibility. An inverse correlation between the frequency of this disorder and the IEC was detected in a multiple orchard trial. Differential methylation state of the ACS1 promoter correlated with both IEC and injury occurrence, indicating epigenetic regulation of ethylene biosynthesis and possibly events leading to disorder development.

MLAA-based RF surface coil attenuation estimation in hybrid PET/MR imaging

NASA Astrophysics Data System (ADS)

Heußer, Thorsten; Rank, Christopher M.; Freitag, Martin T.; Kachelrieß, Marc

2017-03-01

Attenuation correction (AC) for both patient and hardware attenuation of the 511 keV annihilation photons is required for accurate PET quantification. In hybrid PET/MR imaging, AC for stationary hardware components such as patient table and MR head coil is performed using CT{derived attenuation templates. AC for flexible hardware components such as MR radiofrequency (RF) surface coils is more challenging. Registration{based approaches, aligning scaled CT{derived attenuation templates with the current patient position, have been proposed but are not used in clinical routine. Ignoring RF coil attenuation has been shown to result in regional activity underestimation values of up to 18 %. We propose to employ a modified version of the maximum{ likelihood reconstruction of attenuation and activity (MLAA) algorithm to obtain an estimate of the RF coil attenuation. Starting with an initial attenuation map not including the RF coil, the attenuation update of MLAA is applied outside the body outline only, allowing to estimate RF coil attenuation without changing the patient attenuation map. Hence, the proposed method is referred to as external MLAA (xMLAA). In this work, xMLAA for RF surface coil attenuation estimation is investigated using phantom and patient data acquired with a Siemens Biograph mMR. For the phantom data, average activity errors compared to the ground truth was reduced from -8:1% to +0:8% when using the proposed method. Patient data revealed an average activity underestimation of -6:1% for the abdominal region and -5:3% for the thoracic region when ignoring RF coil attenuation.

Forward and reverse control system for induction motors

DOEpatents

Wright, J.T.

1987-09-15

A control system for controlling the direction of rotation of a rotor of an induction motor includes an array of five triacs with one of the triacs applying a current of fixed phase to the windings of the rotor and four of the triacs being switchable to apply either hot ac current or return ac current to the stator windings so as to reverse the phase of current in the stator relative to that of the rotor and thereby reverse the direction of rotation of the rotor. Switching current phase in the stator is accomplished by operating the gates of pairs of the triacs so as to connect either hot ac current or return ac current to the input winding of the stator. 1 fig.

Inhibition of motor cortex excitability with 15Hz transcranial alternating current stimulation (tACS).

PubMed

Zaghi, Soroush; de Freitas Rezende, Larissa; de Oliveira, Laís Machado; El-Nazer, Rasheda; Menning, Sanne; Tadini, Laura; Fregni, Felipe

2010-08-02

There remains a lack of solid evidence showing whether transcranial stimulation with weak alternating current (transcranial alternating current stimulation, tACS) can in fact induce significant neurophysiological effects. Previously, a study in which tACS was applied for 2 and 5min with current density=0.16-0.25A/m(2) was unable to show robust effects on cortical excitability. Here we applied tACS at a significantly higher current density (0.80A/m(2)) for a considerably longer duration (20min) and were indeed able to demonstrate measurable changes to cortical excitability. Our results show that active 15Hz tACS of the motor cortex (electrodes placed at C3 and C4) significantly diminished the amplitude of motor evoked potentials and decreased intracortical facilitation (ICF) as compared to baseline and sham stimulation. In addition, we show that our method of sham tACS is a reliable control condition. These results support the notion that AC stimulation with weak currents can induce significant changes in brain excitability; in this case, 15Hz tACS led to a pattern of inhibition of cortical excitability. We propose that tACS may have a dampening effect on cortical networks and perhaps interfere with the temporal and spatial summation of weak subthreshold electric potentials. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Spectroscopic Determination of the AC Voltammetric Response.

DTIC Science & Technology

1984-01-06

characterization of electrode processes. More recently, with the advent of linear sweep cyclic AC voltanmetry(12’ 13), it has been shown that AC methods...implemented with the same instrumentation ( 7 ) as previously used in MSRS and retains both the qualitative and quantitative utility of linear sweep ...voltammetric response (eg. peak width at balf-height, peak separation and cross-over potential in cyclic AC voltametry ) apply equally well to the SACRS

Field emission from amorphous carbon films grown by electrochemical deposition using methanol liquid

NASA Astrophysics Data System (ADS)

Kiyota, H.; Higashi, M.; Kurosu, T.; Iida, M.

2006-05-01

The field emission from an amorphous carbon (a-C) film grown by electrochemical deposition has been studied. The deposition of the a-C film was accomplished by applying a direct-current potential to a substrate that was immersed in methanol. Both scanning electron microscopy and Raman results indicate that smooth and homogeneous a-C films are grown on specific substrates such as Ti and Al. Field emission measurements demonstrate excellent emission properties such as threshold fields as low as 5 V/μm. Enhancement factors are estimated to be in the range of 1300-1500; these are attributed to local field enhancements around sp2 carbon clusters that are embedded in the a-C films. Emission properties of a-C films grown on Si exhibit a current saturation under higher applied fields. These saturation characteristics are explained by effects of a potential barrier at the interface between the a-C film and the substrate. The interface barrier is reduced by formation of the Ti interfacial layer, suggesting that the formation of TiC decreases the contact resistance between the substrate and the a-C film. Therefore, an approach to use carbide formation at the interface is verified as useful to improve the emission properties of a-C films.

Muscle Microvascular Blood Flow, Oxygenation, pH, and Perfusion Pressure Decrease in Simulated Acute Compartment Syndrome.

PubMed

Challa, Sravya T; Hargens, Alan R; Uzosike, Amarachi; Macias, Brandon R

2017-09-06

The current gold standard for diagnosing acute compartment syndrome (ACS) is an assessment of clinical signs, invasive measurement of intramuscular pressure (IMP), and measurement of local perfusion pressure. However, IMP measurements have several shortcomings, including pain, risk of infection, risk of technique error, plugging of the catheter tip, lack of consensus on the diagnostic pressure threshold, and lack of specificity and sensitivity. The objective of this study was to evaluate muscle hemodynamics, oxygenation, and pH as diagnostic parameters in a human model of ACS. We hypothesized that as IMP increases, muscle microvascular blood flow, oxygenation, and pH decrease in the anterior compartment of a leg at heart level and that they decrease significantly more when the leg is elevated further. An external pneumatic leg pressure chamber, combined with a venous stasis thigh cuff, was used to increase IMP and simulate ACS. Eight healthy subjects (5 males and 3 females; mean age, 26 years) had photoplethysmography and near-infrared spectroscopy-pH sensors placed over the middle aspect of the tibialis anterior muscle of the right (experimental) and left (control) legs. Leg chamber pressure conditions (40, 50, and 60 mm Hg) were applied in a randomized order after baseline measurements were taken. Data were collected continuously for each 11-minute pressure condition, with an 11-minute recovery period after each condition, and the average of the last 6 minutes was used for data analyses. The same protocol was repeated with each subject's legs elevated 12 cm above heart level. Data were analyzed using repeated-measures analysis of variance (ANOVA). As IMP increased, muscle microvascular blood flow (p = 0.01), oxygenation (p < 0.001), and pH (p < 0.001) all decreased significantly in the experimental leg compared with the control leg. At all IMP levels, leg elevation significantly decreased muscle oxygenation (p = 0.013) and perfusion pressure (p = 0.03) compared with the control leg at heart level. These results indicate that muscle microvascular blood flow, oxygenation, pH, and perfusion pressure decrease significantly as IMP increases in a human model of ACS. This study identifies hemodynamic and metabolic parameters as potential noninvasive diagnostic tools for ACS.

Evaluation of the impact of metal artifacts in CT-based attenuation correction of positron emission tomography scans

NASA Astrophysics Data System (ADS)

Wu, Jay; Shih, Cheng-Ting; Chang, Shu-Jun; Huang, Tzung-Chi; Chen, Chuan-Lin; Wu, Tung Hsin

2011-08-01

The quantitative ability of PET/CT allows the widespread use in clinical research and cancer staging. However, metal artifacts induced by high-density metal objects degrade the quality of CT images. These artifacts also propagate to the corresponding PET image and cause a false increase of 18F-FDG uptake near the metal implants when the CT-based attenuation correction (AC) is performed. In this study, we applied a model-based metal artifact reduction (MAR) algorithm to reduce the dark and bright streaks in the CT image and compared the differences between PET images with the general CT-based AC (G-AC) and the MAR-corrected-CT AC (MAR-AC). Results showed that the MAR algorithm effectively reduced the metal artifacts in the CT images of the ACR flangeless phantom and two clinical cases. The MAR-AC also removed the false-positive hot spot near the metal implants of the PET images. We conclude that the MAR-AC could be applied in clinical practice to improve the quantitative accuracy of PET images. Additionally, further use of PET/CT fusion images with metal artifact correction could be more valuable for diagnosis.

Changes in behavioral responses of Lygus lineolaris (Hemiptera: Miridae) from various applied signal voltages during EPG recordings

USDA-ARS?s Scientific Manuscript database

A 3rd-generation AC-DC electrical penetration graph (EPG) monitor was used to study feeding behaviors of pre-reproductive adult Lygus lineolaris (Hemiptera: Miridae) on pinhead (<3mm) cotton squares, applying different signal voltages at several input impedances. The AC-DC monitor allows a user to s...

Urea adsorption by activated carbon prepared from palm kernel shell

NASA Astrophysics Data System (ADS)

Ooi, Chee-Heong; Sim, Yoke-Leng; Yeoh, Fei-Yee

2017-07-01

Dialysis treatment is crucial for patients suffer from renal failure. The dialysis system removes the uremic toxin to a safe level in a patient's body. One of the major limitations of the current hemodialysis system is the capability to efficiently remove uremic toxins from patient's body. Nanoporous materials can be applied to improve the treatment. Palm kernel shell (PKS) biomass generated from palm oil mills can be utilized to prepare high quality nanoporous activated carbon (AC) and applied for urea adsorption in the dialysis system. In this study, AC was prepared from PKS via different carbonization temperatures and followed by carbon dioxide gas activation processes. The physical and chemical properties of the samples were studied. The results show that the porous AC with BET surface areas ranging from 541 to 622 m2g-1 and with total pore volumes varying from 0.254 to 0.297 cm3g-1, are formed with different carbonization temperatures. The equilibrium constant for urea adsorption by AC samples carbonized at 400, 500 and 600 °C are 0.091, 0.287 and 0.334, respectively. The increase of carbonization temperatures from 400 to 600 °C resulted in the increase in urea adsorption by AC predominantly due to increase in surface area. The present study reveals the feasibility of preparing AC with good porosity from PKS and potentially applied in urea adsorption application.

A 65-kV insulated gate bipolar transistor switch applied in damped AC voltages partial discharge detection system.

PubMed

Jiang, J; Ma, G M; Luo, D P; Li, C R; Li, Q M; Wang, W

2014-02-01

Damped AC voltages detection system (DAC) is a productive way to detect the faults in power cables. To solve the problems of large volume, complicated structure and electromagnetic interference in existing switches, this paper developed a compact solid state switch based on electromagnetic trigger, which is suitable for DAC test system. Synchronous electromagnetic trigger of 32 Insulated Gate Bipolar Transistors (IGBTs) in series was realized by the topological structure of single line based on pulse width modulation control technology. In this way, external extension was easily achieved. Electromagnetic trigger and resistor-capacitor-diode snubber circuit were optimized to reduce the switch turn-on time and circular layout. Epoxy encapsulating was chosen to enhance the level of partial discharge initial voltage (PDIV). The combination of synchronous trigger and power supply is proposed to reduce the switch volume. Moreover, we have overcome the drawback of the electromagnetic interference and improved the detection sensitivity of DAC by using capacitor storage energy to maintain IGBT gate driving voltage. The experimental results demonstrated that the solid-state switch, with compact size, whose turn-on time was less than 400 ns and PDIV was more than 65 kV, was able to meet the actual demands of 35 kV DAC test system.

Sum Rules, Classical and Quantum - A Pedagogical Approach

NASA Astrophysics Data System (ADS)

Karstens, William; Smith, David Y.

2014-03-01

Sum rules in the form of integrals over the response of a system to an external probe provide general analytical tools for both experiment and theory. For example, the celebrated f-sum rule gives a system's plasma frequency as an integral over the optical-dipole absorption spectrum regardless of the specific spectral distribution. Moreover, this rule underlies Smakula's equation for the number density of absorbers in a sample in terms of the area under their absorption bands. Commonly such rules are derived from quantum-mechanical commutation relations, but many are fundamentally classical (independent of ℏ) and so can be derived from more transparent mechanical models. We have exploited this to illustrate the fundamental role of inertia in the case of optical sum rules. Similar considerations apply to sum rules in many other branches of physics. Thus, the ``attenuation integral theorems'' of ac circuit theory reflect the ``inertial'' effect of Lenz's Law in inductors or the potential energy ``storage'' in capacitors. These considerations are closely related to the fact that the real and imaginary parts of a response function cannot be specified independently, a result that is encapsulated in the Kramers-Kronig relations. Supported in part by the US Department of Energy, Office of Nuclear Physics under contract DE-AC02-06CH11357.

Capabilities of the new “Universal” AC-DC monitor for electropenetrography (EPG)

USDA-ARS?s Scientific Manuscript database

Electropenetrography (EPG), invented over 50 years ago, is the most rigorous and important means of studying the feeding of piercing-sucking crop pests. The 1st-generation monitor (or AC monitor) used AC applied signal voltage and had fixed amplifier sensitivity (input resistor or Ri) of 106 Ohms. T...

Quantum efficiencies exceeding unity in amorphous silicon solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanmaekelbergh, D.; Lagemaat, J. van de; Schropp, R.E.I.

1994-12-31

The experimental observation of internal quantum efficiencies above unity in crystalline silicon solar cells has brought up the question whether the generation of multiple electron/hole pairs has to be taken into consideration also in solar cells based on direct gap amorphous semiconductors. To study photogenerated carrier dynamics, the authors have applied Intensity Modulated Photocurrent Spectroscopy (IMPS) to hydrogenated amorphous silicon p-i-n solar cells. In the reverse voltage bias region at low illumination intensities it has been observed that the low frequency limit of the AC quantum yield Y increases significantly above unit with decreasing light intensity, indicating that more thanmore » one electron per photon is detected in the external circuit. This phenomenon can be explained by considering trapping and thermal emission of photogenerated carriers at intragap atmospheric dangling bond defect centers.« less

Control of power to an inductively heated part

DOEpatents

Adkins, Douglas R.; Frost, Charles A.; Kahle, Philip M.; Kelley, J. Bruce; Stanton, Suzanne L.

1997-01-01

A process for induction hardening a part to a desired depth with an AC signal applied to the part from a closely coupled induction coil includes measuring the voltage of the AC signal at the coil and the current passing through the coil; and controlling the depth of hardening of the part from the measured voltage and current. The control system determines parameters of the part that are functions of applied voltage and current to the induction coil, and uses a neural network to control the application of the AC signal based on the detected functions for each part.

Control of power to an inductively heated part

DOEpatents

Adkins, D.R.; Frost, C.A.; Kahle, P.M.; Kelley, J.B.; Stanton, S.L.

1997-05-20

A process for induction hardening a part to a desired depth with an AC signal applied to the part from a closely coupled induction coil includes measuring the voltage of the AC signal at the coil and the current passing through the coil; and controlling the depth of hardening of the part from the measured voltage and current. The control system determines parameters of the part that are functions of applied voltage and current to the induction coil, and uses a neural network to control the application of the AC signal based on the detected functions for each part. 6 figs.

Calculation of AC loss in two-layer superconducting cable with equal currents in the layers

NASA Astrophysics Data System (ADS)

Erdogan, Muzaffer

2016-12-01

A new method for calculating AC loss of two-layer SC power transmission cables using the commercial software Comsol Multiphysics, relying on the approach of the equal partition of current between the layers is proposed. Applying the method to calculate the AC-loss in a cable composed of two coaxial cylindrical SC tubes, the results are in good agreement with the analytical ones of duoblock model. Applying the method to calculate the AC-losses of a cable composed of a cylindrical copper former, surrounded by two coaxial cylindrical layers of superconducting tapes embedded in an insulating medium with tape-on-tape and tape-on-gap configurations are compared. A good agreement between the duoblock model and the numerical results for the tape-on-gap cable is observed.

Enhancement of crystal homogeneity of protein crystals under application of an external alternating current electric field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koizumi, H.; Uda, S.; Fujiwara, K.

X-ray diffraction rocking-curve measurements were performed on tetragonal hen egg white (HEW) lysozyme crystals grown with and without the application of an external alternating current (AC) electric field. The crystal quality was assessed by the full width at half maximum (FWHM) value for each rocking curve. For two-dimensional maps of the FWHMs measured on the 440 and the 12 12 0 reflection, the crystal homogeneity was improved under application of an external electric field at 1 MHz, compared with that without. In particular, the significant improvement of the crystal homogeneity was observed for the 12 12 0 reflection.

Electrically tunable transport and high-frequency dynamics in antiferromagnetic S r3I r2O7

NASA Astrophysics Data System (ADS)

Seinige, Heidi; Williamson, Morgan; Shen, Shida; Wang, Cheng; Cao, Gang; Zhou, Jianshi; Goodenough, John B.; Tsoi, Maxim

2016-12-01

We report dc and high-frequency transport properties of antiferromagnetic S r3I r2O7 . Temperature-dependent resistivity measurements show that the activation energy of this material can be tuned by an applied dc electrical bias. The latter allows for continuous variations in the sample resistivity of as much as 50% followed by a reversible resistive switching at higher biases. Such a switching is of high interest for antiferromagnetic applications in high-speed memory devices. Interestingly, we found the switching behavior to be strongly affected by a high-frequency (microwave) current applied to the sample. The microwaves at 3-7 GHz suppress the dc switching and produce resonancelike features that we tentatively associated with the dissipationless magnonics recently predicted to occur in antiferromagnetic insulators subject to ac electric fields. We have characterized the effects of microwave irradiation on electronic transport in S r3I r2O7 as a function of microwave frequency and power, strength and direction of external magnetic field, strength and polarity of applied dc bias, and temperature. Our observations support the potential of antiferromagnetic materials for high-speed/high-frequency spintronic applications.

A novel torsional exciter for modal vibration testing of large rotating machinery

NASA Astrophysics Data System (ADS)

Sihler, Christof

2006-10-01

A novel exciter for applying a dynamic torsional force to a rotating structure is presented in this paper. It has been developed at IPP in order to perform vibration tests with shaft assemblies of large flywheel generators (synchronous machines). The electromagnetic exciter (shaker) needs no fixture to the rotating shaft because the torque is applied by means of the stator winding of an electrical machine. Therefore, the exciter can most easily be applied in cases where a three-phase electrical machine (a motor or generator) is part of the shaft assembly. The oscillating power for the shaker is generated in a separate current-controlled DC circuit with an inductor acting as a buffer storage of magnetic energy. An AC component with adjustable frequency is superimposed on the inductor current in order to generate pulsating torques acting on the rotating shaft with the desired waveform and frequency. Since this torsional exciter does not require an external power source, can easily be installed (without contact to the rotating structure) and provides dynamic torsional forces which are sufficient for multi-megawatt applications, it is best suited for on-site tests of large rotating machinery.

Electroconvection in one-dimensional liquid crystal cells

NASA Astrophysics Data System (ADS)

Huh, Jong-Hoon

2018-04-01

We investigate the alternating current (ac) -driven electroconvection (EC) in one-dimensional cells (1DCs) under the in-plane switching mode. In 1DCs, defect-free EC can be realized. In the presence and absence of external multiplicative noise, the features of traveling waves (TWs), such as their Hopf frequency fH and velocity, are examined in comparison with those of conventional two-dimensional cells (2DCs) accompanying defects of EC rolls. In particular, we show that the defects significantly contribute to the features of the TWs. Additionally, owing to the defect-free EC in the 1DCs, the effects of the ac and noise fields on the TW are clarified. The ac field linearly increases fH, independent of the ac frequency f . The noise increases fH monotonically, but fH does not vary below a characteristic noise intensity VN*. In addition, soliton-like waves and unfamiliar oscillation of EC vortices in 1DCs are observed, in contrast to the localized EC (called worms) and the oscillation of EC rolls in 2DCs.

Active magnetic force microscopy of Sr-ferrite magnet by stimulating magnetization under an AC magnetic field: Direct observation of reversible and irreversible magnetization processes

NASA Astrophysics Data System (ADS)

Cao, Yongze; Kumar, Pawan; Zhao, Yue; Yoshimura, Satoru; Saito, Hitoshi

2018-05-01

Understanding the dynamic magnetization process of magnetic materials is crucial to improving their fundamental properties and technological applications. Here, we propose active magnetic force microscopy for observing reversible and irreversible magnetization processes by stimulating magnetization with an AC magnetic field based on alternating magnetic force microscopy with a sensitive superparamagnetic tip. This approach simultaneously measures sample's DC and AC magnetic fields. We used this microscopy approach to an anisotropic Sr-ferrite (SrF) sintered magnet. This is a single domain type magnet where magnetization mainly changes via magnetic rotation. The proposed method can directly observe the reversible and irreversible magnetization processes of SrF and clearly reveal magnetic domain evolution of SrF (without stimulating magnetization—stimulating reversible magnetization—stimulating irreversible magnetization switching) by slowly increasing the amplitude of the external AC magnetic field. This microscopy approach can evaluate magnetic inhomogeneity and explain the local magnetic process within the permanent magnet.

Performance analyses of Z-source and quasi Z-source inverter for photovoltaic applications

NASA Astrophysics Data System (ADS)

Himabind, S.; Priya, T. Hari; Manjeera, Ch.

2018-04-01

This paper presents the comparative analysis of Z-source and Quasi Z-source converter for renewable energy applications. Due to the dependency of renewable energy sources on external weather conditions the output voltage, current changes accordingly which effects the performance of traditional voltage source and current source inverters connected across it. To overcome the drawbacks of VSI and CSI, Z-source and Quasi Z-source inverter (QZSI) are used, which can perform multiple tasks like ac-to-dc, dc-to-ac, ac-to-ac, dc-to-dc conversion. They can be used for both buck and boost operations, by utilizing the shoot-through zero state. The QZSI is derived from the ZSI topology, with a slight change in the impedance network and it overcomes the drawbacks of ZSI. The QZSI draws a constant current from the source when compared to ZSI. A comparative analysis is performed between Z-source and Quasi Z-source inverter, simulation is performed in MATLAB/Simulink environment.

Interplay between the Dzyaloshinskii-Moriya term and external fields on spin transport in the spin-1/2 one-dimensional antiferromagnet

NASA Astrophysics Data System (ADS)

Lima, L. S.

2018-05-01

We study the effect of the uniform Dzyaloshinskii-Moriya interaction (symmetric exchange anisotropy) and arbitrary oriented external magnetic fields on spin conductivity in the spin-1/2 one-dimensional Heisenberg antiferromagnet. The spin conductivity is calculated employing abelian bosonization and the Kubo formalism of transport. We investigate the influence of three competing phases at zero-temperature, (Néel phase, dimerized phase and gapless Luttinger liquid phase) on the AC spin conductivity.

Design, Fabrication, and Implementation of a Wireless, Passive Implantable Pressure Sensor Based on Magnetic Higher-Order Harmonic Fields

PubMed Central

Tan, Ee Lim; DeRouin, Andrew J.; Pereles, Brandon D.; Ong, Keat Ghee

2011-01-01

A passive and wireless sensor was developed for monitoring pressure in vivo. Structurally, the pressure sensor, referred to as the magneto-harmonic pressure sensor, is an airtight chamber sealed with an elastic pressure membrane. A strip of magnetically-soft material is attached to the bottom of the chamber and a permanent magnet strip is embedded inside the membrane. Under the excitation of an externally applied AC magnetic field, the magnetically-soft strip produces a higher-order magnetic signature that can be remotely detected with an external receiving coil. As ambient pressure varies, the pressure membrane deflects, altering the separation distance between the magnetically-soft strip and the permanent magnet. This shifts the higher-order harmonic signal, allowing for detection of pressure change as a function of harmonic shifting. The wireless, passive nature of this sensor technology allows for continuous long-term pressure monitoring, particularly useful for biomedical applications such as monitoring pressure in aneurysm sac and sphincter of Oddi. In addition to demonstrating its pressure sensing capability, an animal model was used to investigate the efficacy and feasibility of the pressure sensor in a biological environment. PMID:25585564

Propulsion of Active Colloids by Self-Induced Field Gradients.

PubMed

Boymelgreen, Alicia; Yossifon, Gilad; Miloh, Touvia

2016-09-20

Previously, metallodielectric Janus particles have been shown to travel with their dielectric hemisphere forward under low frequency applied electric fields as a result of asymmetric induced-charge electroosmotic flow. Here, it is demonstrated that at high frequencies, well beyond the charge relaxation time of the electric double layer induced around the particle, rather than the velocity decaying to zero, the Janus particles reverse direction, traveling with their metallic hemisphere forward. It is proposed that such motion is the result of a surface force, arising from localized nonuniform electric field gradients, induced by the dual symmetry-breaking of an asymmetric particle adjacent to a wall, which act on the induced dipole of the particle to drive net motion even in a uniform AC field. Although the field is external, since the driving gradient is induced on the particle level, it may be considered an active colloid. We have thus termed this propulsion mechanism "self-dielectrophoresis", to distinguish from traditional dielectrophoresis where the driving nonuniform field is externally fixed and the particle direction is restricted. It is demonstrated theoretically and experimentally that the critical frequency at which the particle reverses direction can be characterized by a nondimensional parameter which is a function of electrolyte concentration and particle size.

Revealing nanoparticle assembly under high pressure.

NASA Astrophysics Data System (ADS)

Fan, Hongyou

Precise control of structural parameters through nanoscale engineering to improve optical and electronic properties of functional nanoparticles continuously remains an outstanding challenge. Previous work on nanoparticle assembly has been conducted largely at ambient pressure. Here I will present a new Stress-Induced Fabrication method in which we applied high pressure or stress to nanoparticle arrays to induce structural phase transition and to consolidate new nanomaterials with precisely controlled structures and tunable properties. By manipulating nanoparticle coupling through external pressure, a reversible change in their assemblies and properties can be achieved and demonstrated. In addition, over a certain threshold, the external pressure will force these nanoparticles into contact, thereby allowing the formation and consolidation of one- to three-dimensional nanostructures. Through stress induced nanoparticle assembly, materials engineering and synthesis become remarkably flexible without relying on traditional crystallization process where atoms/ions are locked in a specific crystal structure. Therefore, morphology or architecture can be readily tuned to produce desirable properties for practical applications. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Driving Force of Plasma Bullet in Atmospheric-Pressure Plasma

NASA Astrophysics Data System (ADS)

Yambe, Kiyoyuki; Masuda, Seiya; Kondo, Shoma

2018-06-01

When plasma is generated by applying high-voltage alternating current (AC), the driving force of the temporally and spatially varying electric field is applied to the plasma. The strength of the driving force of the plasma at each spatial position is different because the electrons constituting the atmospheric-pressure nonequilibrium (cold) plasma move at a high speed in space. If the force applied to the plasma is accelerated only by the driving force, the plasma will be accelerated infinitely. The equilibrium between the driving force and the restricting force due to the collision between the plasma and neutral particles determines the inertial force and the drift velocity of the plasma. Consequently, the drift velocity depends on the strength of the time-averaged AC electric field. The pressure applied by the AC electric field equilibrates with the plasma pressure. From the law of conservation of energy, the pressure equilibrium is maintained by varying the drift velocity of the plasma.

Absorption and Attenuation Coefficients Using the WET Labs ac-s in the Mid-Atlantic Bight: Field Measurements and Data Analysis

NASA Technical Reports Server (NTRS)

Ohi, Nobuaki; Makinen, Carla P.; Mitchell, Richard; Moisan, Tiffany A.

2008-01-01

Ocean color algorithms are based on the parameterization of apparent optical properties as a function of inherent optical properties. WET Labs underwater absorption and attenuation meters (ac-9 and ac-s) measure both the spectral beam attenuation [c (lambda)] and absorption coefficient [a (lambda)]. The ac-s reports in a continuous range of 390-750 nm with a band pass of 4 nm, totaling approximately 83 distinct wavelengths, while the ac-9 reports at 9 wavelengths. We performed the ac-s field measurements at nine stations in the Mid-Atlantic Bight from water calibrations to data analysis. Onboard the ship, the ac-s was calibrated daily using Milli Q-water. Corrections for the in situ temperature and salinity effects on optical properties of water were applied. Corrections for incomplete recovery of the scattered light in the ac-s absorption tube were performed. The fine scale of spectral and vertical distributions of c (lambda) and a (lambda) were described from the ac-s. The significant relationships between a (674) and that of spectrophotometric analysis and chlorophyll a concentration of discrete water samples were observed.

ac electroosmotic pumping induced by noncontact external electrodes.

PubMed

Wang, Shau-Chun; Chen, Hsiao-Ping; Chang, Hsueh-Chia

2007-09-21

Electroosmotic (EO) pumps based on dc electroosmosis is plagued by bubble generation and other electrochemical reactions at the electrodes at voltages beyond 1 V for electrolytes. These disadvantages limit their throughput and offset their portability advantage over mechanical syringe or pneumatic pumps. ac electroosmotic pumps at high frequency (>100 kHz) circumvent the bubble problem by inducing polarization and slip velocity on embedded electrodes,1 but they require complex electrode designs to produce a net flow. We report a new high-throughput ac EO pump design based on induced-polarization on the entire channel surface instead of just on the electrodes. Like dc EO pumps, our pump electrodes are outside of the load section and form a cm-long pump unit consisting of three circular reservoirs (3 mm in diameter) connected by a 1x1 mm channel. The field-induced polarization can produce an effective Zeta potential exceeding 1 V and an ac slip velocity estimated as 1 mmsec or higher, both one order of magnitude higher than earlier dc and ac pumps, giving rise to a maximum throughput of 1 mulsec. Polarization over the entire channel surface, quadratic scaling with respect to the field and high voltage at high frequency without electrode bubble generation are the reasons why the current pump is superior to earlier dc and ac EO pumps.

Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid: single biomarker re-derivation and external validation in three cohorts

PubMed Central

Body, Richard; Sperrin, Matthew; Lewis, Philip S; Burrows, Gillian; Carley, Simon; McDowell, Garry; Buchan, Iain; Greaves, Kim; Mackway-Jones, Kevin

2017-01-01

Background The original Manchester Acute Coronary Syndromes model (MACS) ‘rules in’ and ‘rules out’ acute coronary syndromes (ACS) using high sensitivity cardiac troponin T (hs-cTnT) and heart-type fatty acid binding protein (H-FABP) measured at admission. The latter is not always available. We aimed to refine and validate MACS as Troponin-only Manchester Acute Coronary Syndromes (T-MACS), cutting down the biomarkers to just hs-cTnT. Methods We present secondary analyses from four prospective diagnostic cohort studies including patients presenting to the ED with suspected ACS. Data were collected and hs-cTnT measured on arrival. The primary outcome was ACS, defined as prevalent acute myocardial infarction (AMI) or incident death, AMI or coronary revascularisation within 30 days. T-MACS was built in one cohort (derivation set) and validated in three external cohorts (validation set). Results At the ‘rule out’ threshold, in the derivation set (n=703), T-MACS had 99.3% (95% CI 97.3% to 99.9%) negative predictive value (NPV) and 98.7% (95.3%–99.8%) sensitivity for ACS, ‘ruling out’ 37.7% patients (specificity 47.6%, positive predictive value (PPV) 34.0%). In the validation set (n=1459), T-MACS had 99.3% (98.3%–99.8%) NPV and 98.1% (95.2%–99.5%) sensitivity, ‘ruling out’ 40.4% (n=590) patients (specificity 47.0%, PPV 23.9%). T-MACS would ‘rule in’ 10.1% and 4.7% patients in the respective sets, of which 100.0% and 91.3% had ACS. C-statistics for the original and refined rules were similar (T-MACS 0.91 vs MACS 0.90 on validation). Conclusions T-MACS could ‘rule out’ ACS in 40% of patients, while ‘ruling in’ 5% at highest risk using a single hs-cTnT measurement on arrival. As a clinical decision aid, T-MACS could therefore help to conserve healthcare resources. PMID:27565197

Piezoelectric Pre-Stressed Bending Mechanism for Impact-Driven Energy Harvester

NASA Astrophysics Data System (ADS)

Abdal, A. M.; Leong, K. S.

2017-06-01

This paper experimentally demonstrates and evaluates a piezoelectric power generator bending mechanism based on pre-stressed condition whereby the piezoelectric transducer being bended and remained in the stressed condition before applying a force on the piezoelectric bending structure, which increase the stress on the piezoelectric surface and hence increase the generated electrical charges. An impact force is being exerted onto bending the piezoelectric beam and hence generating electrical power across an external resistive load. The proposed bending mechanism prototype has been manufactured by employing 3D printer technology in order to conduct the evaluation. A free fall test has been conducted as the evaluation method with varying force using a series of different masses and different fall heights. A rectangular piezoelectric harvester beam with the size of 32mm in width, 70mm in length, and 0.55mm in thickness is used to demonstrate the experiment. It can be seen from the experiment that the instantaneous peak to peak AC volt output measured at open-circuit is increasing and saturated at about of 70V when an impact force of about 80N is being applied. It is also found that a maximum power of about 53mW is generated at an impact force of 50N when it is connected to an external resistive load of 0.7KΩ. The reported mechanism is a promising candidate in the application of energy harvesting for powering various wireless sensor nodes (WSN) which is the core of Internet of Things (IoT).

WFPC2 CYCLE 15 Intflat Linearity Check and Filter Rotation Anomaly Monitor

NASA Astrophysics Data System (ADS)

Gonzaga, Shireen

2006-07-01

Intflat observations will be taken to provide a linearity check: the linearity test consists of a series of intflats in F555W, in each gain and each shutter. A combination of intflats, visflats, and earthflats will be used to check the repeatability of filter wheel motions. {Intflat sequences tied to decons, visits 1-18 in prop 10363, have been moved to the cycle 15 decon proposal xxxx for easier scheduling.} Note: long-exposure WFPC2 intflats must be scheduled during ACS anneals to prevent stray light from the WFPC2 lamps from contaminating long ACS external exposures.

Joint DIII-D/EAST Experiments Toward Steady State AT Demonstration

NASA Astrophysics Data System (ADS)

Garofalo, A. M.; Meneghini, O.; Staebler, G. M.; van Zeeland, M. A.; Gong, X.; Ding, S.; Qian, J.; Ren, Q.; Xu, G.; Grierson, B. A.; Solomon, W. M.; Holcomb, C. T.

2015-11-01

Joint DIII-D/EAST experiments on fully noninductive operation at high poloidal beta have demonstrated several attractive features of this regime for a steady-state fusion reactor. Very large bootstrap fraction (>80 %) is desirable because it reduces the demands on external noninductive current drive. High bootstrap fraction with an H-mode edge results in a broad current profile and internal transport barriers (ITBs) at large minor radius, leading to high normalized energy confinement and high MHD stability limits. The ITB radius expands with higher normalized beta, further improving both stability and confinement. Electron density ITB and large Shafranov shift lead to low AE activity in the plasma core and low anomalous fast ion losses. Both the ITB and the current profile show remarkable robustness against perturbations, without external control. Supported by US DOE under DE-FC02-04ER54698, DE-AC02-09CH11466 & DE-AC52-07NA27344 & by NMCFSP under contracts 2015GB102000 and 2015GB110001.

The application of Halbach cylinders to brushless ac servo motors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Atallah, K.; Howe, D.

1998-07-01

Halbach cylinders are applied to brushless ac servo motors. It is shown that a sinusoidal back-emf waveform and a low cogging torque can be achieved without recourse to conventional design features such as distributed windings and/or stator/rotor skew. A technique for imparting a multipole Halbach magnetization distribution on an isotropic permanent magnet cylinder is described, and it is shown that the torque capability of a Halbach ac servo motor can be up to 33% higher than conventional brushless permanent magnet ac motors.

The ACS Exams Institute Undergraduate Chemistry Anchoring Concepts Content Map I: General Chemistry

ERIC Educational Resources Information Center

Holme, Thomas; Murphy, Kristen

2012-01-01

To provide tools for programmatic assessment related to the use of ACS Exams in undergraduate chemistry courses, the ACS Exams Institute has built a content map that applies to the entire undergraduate curriculum. At the top two levels, the grain size of the content classification is large and spans the entire undergraduate curriculum. At the…

Variable-frequency inverter controls torque, speed, and braking in ac induction motors

NASA Technical Reports Server (NTRS)

Nola, F. J.

1974-01-01

Dc to ac inverter provides optimum frequency and voltage to ac induction motor, in response to different motor-load and speed requirements. Inverter varies slip frequency of motor in proportion to required torque. Inverter protects motor from high current surges, controls negative slip to apply braking, and returns energy stored in momentum of load to dc power source.

Magnetization-induced dynamics of a Josephson junction coupled to a nanomagnet

NASA Astrophysics Data System (ADS)

Ghosh, Roopayan; Maiti, Moitri; Shukrinov, Yury M.; Sengupta, K.

2017-11-01

We study the superconducting current of a Josephson junction (JJ) coupled to an external nanomagnet driven by a time-dependent magnetic field both without and in the presence of an external ac drive. We provide an analytic, albeit perturbative, solution for the Landau-Lifshitz (LL) equations governing the coupled JJ-nanomagnet system in the presence of a magnetic field with arbitrary time dependence oriented along the easy axis of the nanomagnet's magnetization and in the limit of weak dimensionless coupling ɛ0 between the JJ and the nanomagnet. We show the existence of Shapiro-type steps in the I -V characteristics of the JJ subjected to a voltage bias for a constant or periodically varying magnetic field and explore the effect of rotation of the magnetic field and the presence of an external ac drive on these steps. We support our analytic results with exact numerical solution of the LL equations. We also extend our results to dissipative nanomagnets by providing a perturbative solution to the Landau-Lifshitz-Gilbert (LLG) equations for weak dissipation. We study the fate of magnetization-induced Shapiro steps in the presence of dissipation both from our analytical results and via numerical solution of the coupled LLG equations. We discuss experiments which can test our theory.

The Effect of Electrokinetic Controlled Wettability on Externally Measured Pressures for a Micro-Fluidic Channel

NASA Astrophysics Data System (ADS)

Zhou, X.; Nolte, D. D.; Pyrak-Nolte, L. J.

2017-12-01

The hysteretic relationship between capillary pressure (Pc) on saturation (S) has been shown to be a projection of a higher-dimensional surface that depends on interfacial area per volume (IAV) as the additional state variable. Most studies that validate the capillary-pressure-saturation-IAV relationship are performed on 2D micro-models or cores where scanning is performed in pressure and not in saturation. We have developed an EWOD technique (electro-wetting on dielectric) to internally manipulate fluid saturation to determine the effect on externally measured pressures. Applying electric fields to electrolytic fluids changes the contact angle among the fluids and the solid. For a parallel-plate electro-wetting set-up, the pressure difference is given by gsl (cosq'EW - cosqEW )/d', where d' is the aperture, qEQ and q'EW are the contact angles before and after the application of voltage, V, and gsl is the interfacial tension between the solid and liquid phases. This pressure difference enables direct control over internal fluid distributions. The contact angle reverts to the original value when V = 0. A sealed micro-model with Electro-Wetting on Dielectric (EWOD) electrodes was fabricated using a PDMS wedge-shaped channel with an entrance width of 1 mm and an exit width of 2 mm. The channel length was 2 mm, and had a depth of 0.9 mm. The PDMS channel was attached to an aluminum plate that served as the ground electrode. An ITO slide coated with PDMS formed the high voltage electrode and was used to seal the micro-model. X-ray Micro-CT scans showed that the contact angle between electrodes changes from from 110˚ (non-wetting) to 70˚ (wetting) for an applied voltage of 318 V AC. By applying voltage to the wedge-shaped micromodel, with the inlet and the outlet opened to the atmosphere, the externally measured capillary pressure remained constant even though the fluid-air interface moved and the saturation increased. For a closed system, the externally measured change in capillary pressure was 30 Pa and the saturation in the channel increased. EWOD provides method to assess the contributions of wettability to the fundamental physics of immiscible fluids in analog porous media. Acknowledgment: This research was supported by the National Science Foundation (1314663-EAR).

75 FR 10411 - Borrower Rights; Effective Interest Rates; Effective Date

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-08

... FARM CREDIT ADMINISTRATION 12 CFR Part 617 RIN 3052-AC45 Borrower Rights; Effective Interest Rates; Effective Date AGENCY: Farm Credit Administration. ACTION: Notice of effective date. SUMMARY: The Farm... directly tied to a widely publicized external index receive appropriate disclosure of interest rate changes...

Transient electroosmotic flow induced by AC electric field in micro-channel with patchwise surface heterogeneities.

PubMed

Luo, Win-Jet

2006-03-15

This paper investigates two-dimensional, time-dependent electroosmotic flow driven by an AC electric field via patchwise surface heterogeneities distributed along the micro-channel walls. The time-dependent flow fields through the micro-channel are simulated for various patchwise heterogeneous surface patterns using the backwards-Euler time stepping numerical method. Different heterogeneous surface patterns are found to create significantly different electrokinetic transport phenomena. The transient behavior characteristics of the generated electroosmotic flow are then discussed in terms of the influence of the patchwise surface heterogeneities, the direction of the applied AC electric field, and the velocity of the bulk flow. It is shown that the presence of oppositely charged surface heterogeneities on the micro-channel walls results in the formation of localized flow circulations within the bulk flow. These circulation regions grow and decay periodically in phase with the applied periodic AC electric field intensity. The location and rotational direction of the induced circulations are determined by the directions of the bulk flow velocity and the applied electric field.

Electromagnetic Induction of Zerovalent Iron (ZVI) Powder and Nanoscale Zerovalent Iron (NZVI) Particles Enhances Dechlorination of Trichloroethylene in Contaminated Groundwater and Soil: Proof of Concept.

PubMed

Phenrat, Tanapon; Thongboot, Thippawan; Lowry, Gregory V

2016-01-19

This study evaluates the concept of using zerovalent iron (ZVI) powder or nanoscale zerovalent iron (NZVI) particles in combination with a low frequency (150 kHz) AC electromagnetic field (AC EMF) to effectively remove trichloroethylene (TCE) from groundwater and saturated soils. ZVI and NZVI are ferromagnetic, which can induce heat under applied AC EMF. The heat generated by ZVI and NZVI induction can increase the rate of dechlorination, according to Arrhenius' equation, and increase the rate of TCE desorption from TCE-sorbed soil. Both dechlorination and TCE desorption enhance the overall TCE removal rate. We evaluated this novel concept in laboratory batch reactors. We found that both ZVI and NZVI can induce heat under applied AC EMF up to 120 °C in 20 min. Using ZVI and NZVI with AC EMF enhanced dechlorination of dissolved TCE (no soil) up to 4.96-fold. In addition to increasing the temperature by ZVI and NZVI induction heating, AC EMF increased intrinsic ZVI and NZVI reactivity, ostensibly due to accelerated corrosion, as demonstrated by the increased ORP. In a soil-water-TCE system, NZVI together with AC EMF thermally enhanced desorption of TCE from soil and increased the degradation of TCE up to 5.36-fold compared to the absence of AC EMF. For the first time, this study indicates the potential for ZVI and NZVI coupled with AC EMF as a combined remediation technique for increasing the rate and completeness of in situ cleanup of adsorbed phase contaminants.

Evaluation of a nontoxic rigid polymer as connecting bar in external skeletal fixators.

PubMed

Störk, Christoph K; Canivet, Philippe; Baidak, Alexandre A; Balligand, Marc H

2003-01-01

To investigate the mechanical characteristics of a nontoxic, low-cost, rigid polymer (RP) and to compare the structural and mechanical properties of a full-frame external skeletal fixator (ESF) with either RP connecting bars, polymethylmethacrylate (PMMA) connecting bars, or stainless-steel (SS) clamps and connecting bars. In vitro mechanical evaluation. Mechanical properties were assessed using an in vitro bone fracture model with a bilateral uniplanar ESF (type II). Identical ESF were built with connecting bars using RP (n = 8), PMMA (n = 8), and SS connecting bars and clamps (System Meynard; n = 3). Nondestructive mechanical tests were performed in uniaxial compression (AC) and craniocaudal (CC) 4-point bending, as well as fatigue AC. Composite stiffness for each specimen and for each loading mode was calculated from 6 replicate measures using the slope of the load displacement curve at small displacements. RP, PMMA, and SS ESF constructs yielded mean +/- SD composite stiffness values of 227 +/- 15, 381 +/- 30, and 394 +/- 9 N/mm in AC and of 35 +/- 2, 24 +/- 2, and 15 +/- 0 N/mm in CC, respectively. Structural and mechanical properties of RP are satisfactorily rigid and fatigue resistant for its use as a connecting bar in ESF. RP connecting bars in an ESF are a reliable, versatile, nontoxic and inexpensive option for the veterinary surgeon. Copyright 2003 by The American College of Veterinary Surgeons

Calorimetric method of ac loss measurement in a rotating magnetic field.

PubMed

Ghoshal, P K; Coombs, T A; Campbell, A M

2010-07-01

A method is described for calorimetric ac-loss measurements of high-T(c) superconductors (HTS) at 80 K. It is based on a technique used at 4.2 K for conventional superconducting wires that allows an easy loss measurement in parallel or perpendicular external field orientation. This paper focuses on ac loss measurement setup and calibration in a rotating magnetic field. This experimental setup is to demonstrate measuring loss using a temperature rise method under the influence of a rotating magnetic field. The slight temperature increase of the sample in an ac-field is used as a measure of losses. The aim is to simulate the loss in rotating machines using HTS. This is a unique technique to measure total ac loss in HTS at power frequencies. The sample is mounted on to a cold finger extended from a liquid nitrogen heat exchanger (HEX). The thermal insulation between the HEX and sample is provided by a material of low thermal conductivity, and low eddy current heating sample holder in vacuum vessel. A temperature sensor and noninductive heater have been incorporated in the sample holder allowing a rapid sample change. The main part of the data is obtained in the calorimetric measurement is used for calibration. The focus is on the accuracy and calibrations required to predict the actual ac losses in HTS. This setup has the advantage of being able to measure the total ac loss under the influence of a continuous moving field as experienced by any rotating machines.

Local Network-Level Integration Mediates Effects of Transcranial Alternating Current Stimulation.

PubMed

Fuscà, Marco; Ruhnau, Philipp; Neuling, Toralf; Weisz, Nathan

2018-05-01

Transcranial alternating current stimulation (tACS) has been proposed as a tool to draw causal inferences on the role of oscillatory activity in cognitive functioning and has the potential to induce long-term changes in cerebral networks. However, effectiveness of tACS underlies high variability and dependencies, which, as previous modeling works have suggested, may be mediated by local and network-level brain states. We used magnetoencephalography to record brain activity from 17 healthy participants at rest as they kept their eyes open (EO) or eyes closed (EC) while being stimulated with sham, weak, or strong alpha-tACS using a montage commonly assumed to target occipital areas. We reconstructed the activity of sources in all stimulation conditions by means of beamforming. The analysis of resting-state brain activity revealed an interaction of the external stimulation with the endogenous alpha power increase from EO to EC. This interaction was localized to the posterior cingulate, a region remote from occipital cortex. This suggests state-dependent (EO vs. EC) long-range effects of tACS. In a follow-up analysis of this online-tACS effect, we find evidence that this state-dependency effect is mediated by functional network changes: connection strength from the precuneus was significantly correlated with the state-dependency effect in the posterior cingulate during tACS. No analogous correlation could be found for alpha power modulations in occipital cortex. Altogether, this is the first strong evidence to illustrate how functional network architectures can shape tACS effects.

Use of alternating and pulsed direct current electrified fields for zebra mussel control

USGS Publications Warehouse

Luoma, James A.; Dean, Jan C.; Severson, Todd J.; Wise, Jeremy K.; Barbour, Matthew

2017-01-01

Alternatives to chemicals for controlling dreissenid mussels are desirable for environmental compatibility, but few alternatives exist. Previous studies have evaluated the use of electrified fields for stunning and/or killing planktonic life stages of dreissenid mussels, however, the available literature on the use of electrified fields to control adult dreissenid mussels is limited. We evaluated the effects of sinusoidal alternating current (AC) and 20% duty cycle square-wave pulsed direct current (PDC) exposure on the survival of adult zebra mussels at water temperatures of 10, 15, and 22 °C. Peak voltage gradients of ~ 17 and 30 Vp/cm in the AC and PDC exposures, respectively, were continuously applied for 24, 48, or 72 h. Peak power densities ranged from 77,999 to 107,199 µW/cm3 in the AC exposures and 245,320 to 313,945 µW/cm3 in the PDC exposures. The peak dose ranged from 6,739 to 27,298 Joules/cm3 and 21,306 to 80,941 Joules/cm3 in the AC and PDC exposures, respectively. The applied power ranged from 16.6 to 68.9 kWh in the AC exposures and from 22.2 to 86.4 kWh in the PDC exposures. Mortality ranged from 2.7 to 92.7% in the AC exposed groups and from 24.0 to 98.7% in PDC exposed groups. Mortality increased with corresponding increases in water temperature and exposure duration, and we observed more zebra mussel mortality in the PDC exposures. Exposures conducted with AC required less of a peak dose (Joules/cm3) but more applied power (kWh) to achieve the same level of adult zebra mussel mortality as corresponding PDC exposures. The results demonstrate that 20% duty cycle square-wave PDC requires less energy than sinusoidal AC to inducing the same level of adult zebra mussel mortality.

Influence of a uniform transverse magnetic field on the thermo-hydrodynamic stability in water-based nanofluids with metallic nanoparticles using the generalized Buongiorno's mathematical model

NASA Astrophysics Data System (ADS)

Wakif, Abderrahim; Boulahia, Zoubair; Mishra, S. R.; Mehdi Rashidi, Mohammad; Sehaqui, Rachid

2018-05-01

The onset of nanofluid convection in the presence of an externally applied magnetic field is investigated numerically based on the non-homogeneous Buongiorno's mathematical model. In this study, we use the latest experimental correlations and powerful analytical models for expressing the thermo-physical properties of some electrically conducting nanofluids, such as copper-water, sliver-water and gold-water nanofluids, in which the Brownian motion and thermophoresis effects on slip flow in nanofluids are taken into account in this model ( i.e., two-phase transport model). In this paper, we assume that the nanofluid has Newtonian behavior, confined horizontally between two infinite impermeable boundaries and heated from below, in such a way that the nanoparticles tend to concentrate near the upper wall. Considering the basic state of the nanofluidic system, the linear stability theory has been successfully applied to obtain the principal stability equations, which are solved numerically for an imposed volumetric fraction of nanoparticles and no-slip impermeable conditions at the isothermal walls bounding the nanofluid layer. The linear boundary-value problem obtained in this investigation is converted into a pure initial-value problem, so that we can solve it numerically by the fourth-fifth-order Runge-Kutta-Fehlberg method. The generalized Buongiorno's mathematical model proposed in this study allows performing a highly accurate computational analysis. In addition, the obtained results show that the stability of the studied nanofluidic system depends on several parameters, namely, the magnetic Chandrasekhar number Q , the reference value for the volumetric fraction of nanoparticles φ_0 and the size of nanoparticles d_p . In this analysis, the thermo-hydrodynamic stability of the studied nanofluid is controlled through the critical thermal Rayleigh number R_{ac} , which characterizes the onset of convection cells, whose size is L_c=2π/a_c . Furthermore, the effects of various pertinent parameters on the critical stability parameters R_{ac} and a_c are discussed in more detail through graphical and tabular illustrations, for three types of nanofluids including copper-water, sliver-water, and gold-water.

Magnetic and magnetothermal studies of iron boride (FeB) nanoparticles

NASA Astrophysics Data System (ADS)

Hamayun, M. Asif; Abramchuk, Mykola; Alnasir, Hisham; Khan, Mohsin; Pak, Chongin; Lenhert, Steven; Ghazanfari, Lida; Shatruk, Michael; Manzoor, Sadia

2018-04-01

We report magnetic and magnetothermal properties of iron boride (FeB) nanoparticles prepared by surfactant-assisted ball milling of arc-melted bulk ingots of this binary alloy. Size-dependent magnetic properties were used to identify the transition to the single domain limit and calculate the anisotropy and exchange stiffness constants for this system. Extended milling is seen to produce coercivity enhancement and exchange bias of up to 270 Ôe at room temperature. The magnetothermal properties were investigated by measuring the response of single domain FeB nanoparticles to externally applied ac magnetic fields. All investigated particle sizes show a significant heating response, demonstrating their potential as candidates for magnetically induced hyperthermia. FeB nanoparticles were encapsulated into lipophilic domains of liposomes as evidenced by TEM. Exposure of HeLa cells to these liposomes did not affect cell viability, suggesting the biocompatibility of these new magnetic nanomaterials.

Electroosmotic flow in microchannels with arbitrary geometry and arbitrary distribution of wall charge.

PubMed

Xuan, Xiangchun; Li, Dongqing

2005-09-01

General solutions are developed for direct current (DC) and alternating current (AC) electroosmotic flows in microfluidic channels with arbitrary cross-sectional geometry and arbitrary distribution of wall charge (zeta potential). The applied AC electric field can also be of arbitrary waveform. By proposing a nondimensional time scale varpi defined as the ratio of the diffusion time of momentum across the electric double-layer thickness to the period of the applied electric field, we demonstrate analytically that the Helmholtz-Smoluchowski electroosmotic velocity is an appropriate slip condition for AC electroosmotic flows in typical microfluidic applications. With this slip condition approach, electroosmotic flows in rectangular and asymmetric trapezoidal microchannels with nonuniform wall charge, as examples, are investigated. The unknown constants in the proposed general solutions are numerically determined with a least-squares method through matching the boundary conditions. We find that the wall charge affects significantly the electroosmotic flow while the channel geometry does not. Moreover, the flow feature is characterized by another nondimensional time scale Omega defined as the ratio of the diffusion time of momentum across the channel hydraulic radius to the period of the applied electric field. The onset of phase shift between AC electroosmotic velocity and applied electric field is also examined analytically.

Energy saving in ac generators

NASA Technical Reports Server (NTRS)

Nola, F. J.

1980-01-01

Circuit cuts no-load losses, without sacrificing full-load power. Phase-contro circuit includes gate-controlled semiconductor switch that cuts off applied voltage for most of ac cycle if generator idling. Switch "on" time increases when generator is in operation.

ac electroosmotic pumping induced by noncontact external electrodes

PubMed Central

Wang, Shau-Chun; Chen, Hsiao-Ping; Chang, Hsueh-Chia

2007-01-01

Electroosmotic (EO) pumps based on dc electroosmosis is plagued by bubble generation and other electrochemical reactions at the electrodes at voltages beyond 1 V for electrolytes. These disadvantages limit their throughput and offset their portability advantage over mechanical syringe or pneumatic pumps. ac electroosmotic pumps at high frequency (>100 kHz) circumvent the bubble problem by inducing polarization and slip velocity on embedded electrodes,1 but they require complex electrode designs to produce a net flow. We report a new high-throughput ac EO pump design based on induced-polarization on the entire channel surface instead of just on the electrodes. Like dc EO pumps, our pump electrodes are outside of the load section and form a cm-long pump unit consisting of three circular reservoirs (3 mm in diameter) connected by a 1×1 mm channel. The field-induced polarization can produce an effective Zeta potential exceeding 1 V and an ac slip velocity estimated as 1 mm∕sec or higher, both one order of magnitude higher than earlier dc and ac pumps, giving rise to a maximum throughput of 1 μl∕sec. Polarization over the entire channel surface, quadratic scaling with respect to the field and high voltage at high frequency without electrode bubble generation are the reasons why the current pump is superior to earlier dc and ac EO pumps. PMID:19693362

Critical frequency for coalescence of emulsions in an AC electric field

NASA Astrophysics Data System (ADS)

Liu, Zhou; Ali, Faizi Hammad; Shum, Ho Cheung

2017-11-01

Applying an electric field to trigger the coalescence of emulsions has been applied in various applications which include crude oil recovery, emulsion stability characterization as well as pico-injection and droplet-based chemical reaction in microfluidics. In this work, we systematically investigated the responses of surfactant-stabilized emulsions to a controlled AC electric field using a customer-built chip. At a given amplitude of the AC voltage, we found a critical frequency beyond which the emulsions remain stable. When the frequency is decreased to below the critical value, emulsions coalesce immediately. Such critical frequency is found to be dependent of amplitude of the AC voltage, viscosity of the fluids, concentration and type of the surfactant as well as the electric conductivity of the droplet phase. Using a model based on the drainage of thin film, we have explored the mechanism behind and interpret this phenomenon systematically. Our work extends the understanding of the electro-coalescence of emulsions and can be beneficial for any applications involve the coalescence of droplets in an AC electric field.

A method for determining electrophoretic and electroosmotic mobilities using AC and DC electric field particle displacements.

PubMed

Oddy, M H; Santiago, J G

2004-01-01

We have developed a method for measuring the electrophoretic mobility of submicrometer, fluorescently labeled particles and the electroosmotic mobility of a microchannel. We derive explicit expressions for the unknown electrophoretic and the electroosmotic mobilities as a function of particle displacements resulting from alternating current (AC) and direct current (DC) applied electric fields. Images of particle displacements are captured using an epifluorescent microscope and a CCD camera. A custom image-processing code was developed to determine image streak lengths associated with AC measurements, and a custom particle tracking velocimetry (PTV) code was devised to determine DC particle displacements. Statistical analysis was applied to relate mobility estimates to measured particle displacement distributions.

A simple method to eliminate shielding currents for magnetization perpendicular to superconducting tapes wound into coils

NASA Astrophysics Data System (ADS)

Kajikawa, Kazuhiro; Funaki, Kazuo

2011-12-01

Application of an external AC magnetic field parallel to superconducting tapes helps in eliminating the magnetization caused by the shielding current induced in the flat faces of the tapes. This method helps in realizing a magnet system with high-temperature superconducting tapes for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) applications. The effectiveness of the proposed method is validated by numerical calculations carried out using the finite-element method and experiments performed using a commercially available superconducting tape. The field uniformity for a single-layer solenoid coil after the application of an AC field is also estimated by a theoretical consideration.

[Prehospital use of haemostatic dressing QuikClot ACS+™ for hemorrhage control of a perineal trauma].

PubMed

Travers, S; Dubourg, O; Ribeiro Parenti, L; Lefort, H; Albarello, S; Domanski, L

2012-12-01

First responders are sometimes confronted with external uncontrolled haemorrhage despite compression, bandages, and tourniquets. Several topical haemostatic agents were developed to try to face these situations. Their application was mainly described and studied in military environment. We report the case of a worker victim of an accident of construction site with hemorrhagic perineal trauma for whom the use of a haemostatic bandage QuikClot ACS+™ (Z-Medica) seemed to us particularly useful in prehospital setting. Copyright © 2012 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

Ac-loss measurement of a DyBCO-Roebel assembled coated conductor cable (RACC)

NASA Astrophysics Data System (ADS)

Schuller, S.; Goldacker, W.; Kling, A.; Krempasky, L.; Schmidt, C.

2007-10-01

Low ac-loss HTS cables for transport currents well above 1 kA are required for application in transformers and generators and are taken into consideration for future generations of fusion reactor coils. Coated conductors (CC) are suitable candidates for high field application at an operation temperature around 50-77 K, which is a crucial precondition for economical cooling costs. We prepared a short length of a Roebel bar cable made of industrial DyBCO coated conductor (Theva Company, Germany). Meander shaped tapes of 4 mm width with a twist pitch of 122 mm were cut from 10 mm wide CC tapes using a specially designed tool. Eleven of these strands were assembled to a cable. The electrical and mechanical connection of the tapes was achieved using a silver powder filled conductive epoxy resin. Ac-losses of a short sample in an external ac field were measured as a function of frequency and field amplitude in transverse and parallel field orientations. In addition, the coupling current time constant of the sample was directly measured.

Method of driving liquid flow at or near the free surface using magnetic microparticles

DOEpatents

Snezhko, Oleksiy [Woodridge, IL; Aronson, Igor [Darien, IL; Kwok, Wai-Kwong [Evanston, IL; Belkin, Maxim V [Woodridge, IL

2011-10-11

The present invention provides a method of driving liquid flow at or near a free surface using self-assembled structures composed of magnetic particles subjected to an external AC magnetic field. A plurality of magnetic particles are supported at or near a free surface of liquid by surface tension or buoyancy force. An AC magnetic field traverses the free surface and dipole-dipole interaction between particles produces in self-assembled snake structures which oscillate at the frequency of the traverse AC magnetic field. The snake structures independently move across the free surface and may merge with other snake structures or break up and coalesce into additional snake structures experiencing independent movement across the liquid surface. During this process, the snake structures produce asymmetric flow vortices across substantially the entirety of the free surface, effectuating liquid flow across the free surface.

Method for measuring the alternating current half-wave voltage of a Mach-Zehnder modulator based on opto-electronic oscillation.

PubMed

Hong, Jun; Chen, Dongchu; Peng, Zhiqiang; Li, Zulin; Liu, Haibo; Guo, Jian

2018-05-01

A new method for measuring the alternating current (AC) half-wave voltage of a Mach-Zehnder modulator is proposed and verified by experiment in this paper. Based on the opto-electronic self-oscillation technology, the physical relationship between the saturation output power of the oscillating signal and the AC half-wave voltage is revealed, and the value of the AC half-wave voltage is solved by measuring the saturation output power of the oscillating signal. The experimental results show that the measured data of this new method involved are in agreement with a traditional method, and not only an external microwave signal source but also the calibration for different frequency measurements is not needed in our new method. The measuring process is simplified with this new method on the premise of ensuring the accuracy of measurement, and it owns good practical value.

Differences in receptor-evoked membrane electrical responses in native and mRNA-injected Xenopus oocytes.

PubMed

Oron, Y; Gillo, B; Gershengorn, M C

1988-06-01

Xenopus laevis oocytes are giant cells suitable for studies of plasma membrane receptors and signal transduction pathways because of their capacity to express receptors after injection of heterologous mRNA. We studied depolarizing chloride currents evoked by acetylcholine (AcCho) in native oocytes ("intrinsic AcCho response"), by thyrotropin-releasing hormone (TRH) in oocytes injected with pituitary (GH3) cell RNA ("acquired TRH response"), and by AcCho in oocytes injected with rat brain RNA ("acquired AcCho response"). We found differences in the latencies and patterns of these responses and in the responsiveness to these agonists when applied to the animal or vegetal hemisphere, even though all of the responses are mediated by the same signal transduction pathway. The common intrinsic response to AcCho is characterized by minimal latency (0.86 +/- 0.05 sec), a rapid, transient depolarization followed by a distinct prolonged depolarization, and larger responses obtained after AcCho application at the vegetal rather than the animal hemisphere. By contrast, the acquired responses to TRH and AcCho are characterized by much longer latencies, 9.3 +/- 1.0 and 5.5 +/- 0.8 sec, respectively, and large rapid depolarizations followed by less distinct prolonged depolarizations. The responsiveness on the two hemispheres to TRH and AcCho in mRNA-injected oocytes is opposite to that for the common intrinsic AcCho response in that there is a much greater response when agonist is applied at the animal rather than the vegetal hemisphere. We suggest that the differences in these responses are caused by differences in the intrinsic properties of these receptors. Because different receptors appear to be segregated in the same oocyte in distinct localizations, Xenopus oocytes may be an important model system in which to study receptor sorting in polarized cells.

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation

PubMed Central

Zanto, Theodore P.; van Schouwenburg, Martine R.; Gazzaley, Adam

2017-01-01

Multitasking is associated with the generation of stimulus-locked theta (4–7 Hz) oscillations arising from prefrontal cortex (PFC). Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that influences endogenous brain oscillations. Here, we investigate whether applying alternating current stimulation within the theta frequency band would affect multitasking performance, and explore tACS effects on neurophysiological measures. Brief runs of bilateral PFC theta-tACS were applied while participants were engaged in a multitasking paradigm accompanied by electroencephalography (EEG) data collection. Unlike an active control group, a tACS stimulation group showed enhancement of multitasking performance after a 90-minute session (F1,35 = 6.63, p = 0.01, ηp2 = 0.16; effect size = 0.96), coupled with significant modulation of posterior beta (13–30 Hz) activities (F1,32 = 7.66, p = 0.009, ηp2 = 0.19; effect size = 0.96). Across participant regression analyses indicated that those participants with greater increases in frontal theta, alpha and beta oscillations exhibited greater multitasking performance improvements. These results indicate frontal theta-tACS generates benefits on multitasking performance accompanied by widespread neuronal oscillatory changes, and suggests that future tACS studies with extended treatments are worth exploring as promising tools for cognitive enhancement. PMID:28562642

Enhancement of multitasking performance and neural oscillations by transcranial alternating current stimulation.

PubMed

Hsu, Wan-Yu; Zanto, Theodore P; van Schouwenburg, Martine R; Gazzaley, Adam

2017-01-01

Multitasking is associated with the generation of stimulus-locked theta (4-7 Hz) oscillations arising from prefrontal cortex (PFC). Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that influences endogenous brain oscillations. Here, we investigate whether applying alternating current stimulation within the theta frequency band would affect multitasking performance, and explore tACS effects on neurophysiological measures. Brief runs of bilateral PFC theta-tACS were applied while participants were engaged in a multitasking paradigm accompanied by electroencephalography (EEG) data collection. Unlike an active control group, a tACS stimulation group showed enhancement of multitasking performance after a 90-minute session (F1,35 = 6.63, p = 0.01, ηp2 = 0.16; effect size = 0.96), coupled with significant modulation of posterior beta (13-30 Hz) activities (F1,32 = 7.66, p = 0.009, ηp2 = 0.19; effect size = 0.96). Across participant regression analyses indicated that those participants with greater increases in frontal theta, alpha and beta oscillations exhibited greater multitasking performance improvements. These results indicate frontal theta-tACS generates benefits on multitasking performance accompanied by widespread neuronal oscillatory changes, and suggests that future tACS studies with extended treatments are worth exploring as promising tools for cognitive enhancement.

Successful enrichment of the ubiquitous freshwater acI Actinobacteria.

PubMed

Garcia, Sarahi L; McMahon, Katherine D; Grossart, Hans-Peter; Warnecke, Falk

2014-02-01

Actinobacteria of the acI lineage are often the numerically dominant bacterial phylum in surface freshwaters, where they can account for > 50% of total bacteria. Despite their abundance, there are no described isolates. In an effort to obtain enrichment of these ubiquitous freshwater Actinobacteria, diluted freshwater samples from Lake Grosse Fuchskuhle, Germany, were incubated in 96-well culture plates. With this method, a successful enrichment containing high abundances of a member of the lineage acI was established. Phylogenetic classification showed that the acI Actinobacteria of the enrichment belonged to the acI-B2 tribe, which seems to prefer acidic lakes. This enrichment grows to low cell densities and thus the oligotrophic nature of acI-B2 was confirmed. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

In situ sediment treatment using activated carbon: a demonstrated sediment cleanup technology.

PubMed

Patmont, Clayton R; Ghosh, Upal; LaRosa, Paul; Menzie, Charles A; Luthy, Richard G; Greenberg, Marc S; Cornelissen, Gerard; Eek, Espen; Collins, John; Hull, John; Hjartland, Tore; Glaza, Edward; Bleiler, John; Quadrini, James

2015-04-01

This paper reviews general approaches for applying activated carbon (AC) amendments as an in situ sediment treatment remedy. In situ sediment treatment involves targeted placement of amendments using installation options that fall into two general approaches: 1) directly applying a thin layer of amendments (which potentially incorporates weighting or binding materials) to surface sediment, with or without initial mixing; and 2) incorporating amendments into a premixed, blended cover material of clean sand or sediment, which is also applied to the sediment surface. Over the past decade, pilot- or full-scale field sediment treatment projects using AC-globally recognized as one of the most effective sorbents for organic contaminants-were completed or were underway at more than 25 field sites in the United States, Norway, and the Netherlands. Collectively, these field projects (along with numerous laboratory experiments) have demonstrated the efficacy of AC for in situ treatment in a range of contaminated sediment conditions. Results from experimental studies and field applications indicate that in situ sequestration and immobilization treatment of hydrophobic organic compounds using either installation approach can reduce porewater concentrations and biouptake significantly, often becoming more effective over time due to progressive mass transfer. Certain conditions, such as use in unstable sediment environments, should be taken into account to maximize AC effectiveness over long time periods. In situ treatment is generally less disruptive and less expensive than traditional sediment cleanup technologies such as dredging or isolation capping. Proper site-specific balancing of the potential benefits, risks, ecological effects, and costs of in situ treatment technologies (in this case, AC) relative to other sediment cleanup technologies is important to successful full-scale field application. Extensive experimental studies and field trials have shown that when applied correctly, in situ treatment via contaminant sequestration and immobilization using a sorbent material such as AC has progressed from an innovative sediment remediation approach to a proven, reliable technology. © 2014 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC.

Artificial neural networks for AC losses prediction in superconducting round filaments

NASA Astrophysics Data System (ADS)

Leclerc, J.; Makong Hell, L.; Lorin, C.; Masson, P. J.

2016-06-01

An extensive and fast method to estimate superconducting AC losses within a superconducting round filament carrying an AC current and subjected to an elliptical magnetic field (both rotating and oscillating) is presented. Elliptical fields are present in rotating machine stators and being able to accurately predict AC losses in fully superconducting machines is paramount to generating realistic machine designs. The proposed method relies on an analytical scaling law (ASL) combined with two artificial neural network (ANN) estimators taking 9 input parameters representing the superconductor, external field and transport current characteristics. The ANNs are trained with data generated by finite element (FE) computations with a commercial software (FlexPDE) based on the widely accepted H-formulation. After completion, the model is validated through comparison with additional randomly chosen data points and compared for simple field configurations to other predictive models. The loss estimation discrepancy is about 3% on average compared to the FEA analysis. The main advantages of the model compared to FE simulations is the fast computation time (few milliseconds) which allows it to be used in iterated design processes of fully superconducting machines. In addition, the proposed model provides a higher level of fidelity than the scaling laws existing in literature usually only considering pure AC field.

Tapered oral dexamethasone for the acute chest syndrome of sickle cell disease

PubMed Central

Quinn, Charles T.; Stuart, Marie J.; Kesler, Karen; Ataga, Kenneth I.; Wang, Winfred C.; Styles, Lori; Smith-Whitley, Kim; Wun, Ted; Raj, Ahsok; Hsu, Lewis L.; Krishnan, Suba; Kuypers, Frans A; Setty, B. N. Yamaja; Rhee, Seungshin; Key, Nigel S.; Buchanan, George R.

2011-01-01

Summary Tapered oral dexamethasone for acute chest syndrome (ACS) in sickle cell anaemia was studied using a novel ACS assessment tool and investigational biomarkers. Twelve participants were randomized (mean age 17.3 years) before early study termination. Dexamethasone decreased duration of hospitalization for ACS by 20.8 h compared to placebo (P=0.024). Rebound pain occurred in both groups (3 dexamethasone vs. 1 placebo). Overall, dexamethasone decreased the leucocyte activation biomarker, sL-selectin; however, participants with rebound pain had higher sL-selectin within 24 h of treatment (dexamethasone or placebo). This ACS assessment tool was feasibly applied, and sL-selectin is a promising biomarker of ACS therapy. PMID:21848879

Activated carbon amendment to sequester PAHs in contaminated soil: a lysimeter field trial.

PubMed

Hale, Sarah E; Elmquist, Marie; Brändli, Rahel; Hartnik, Thomas; Jakob, Lena; Henriksen, Thomas; Werner, David; Cornelissen, Gerard

2012-04-01

Activated carbon (AC) amendment is an innovative method for the in situ remediation of contaminated soils. A field-scale AC amendment of either 2% powder or granular AC (PAC and GAC) to a PAH contaminated soil was carried out in Norway. The PAH concentration in drainage water from the field plot was measured with a direct solvent extraction and by deploying polyoxymethylene (POM) passive samplers. In addition, POM samplers were dug directly in the AC amended and unamended soil in order to monitor the reduction in free aqueous PAH concentrations in the soil pore water. The total PAH concentration in the drainage water, measured by direct solvent extraction of the water, was reduced by 14% for the PAC amendment and by 59% for GAC, 12 months after amendment. Measurements carried out with POM showed a reduction of 93% for PAC and 56% for GAC. The free aqueous PAH concentration in soil pore water was reduced 93% and 76%, 17 and 28 months after PAC amendment, compared to 84% and 69% for GAC. PAC, in contrast to GAC, was more effective for reducing freely dissolved concentrations than total dissolved ones. This could tentatively be explained by leaching of microscopic AC particles from PAC. Secondary chemical effects of the AC amendment were monitored by considering concentration changes in dissolved organic carbon (DOC) and nutrients. DOC was bound by AC, while the concentrations of nutrients (NO(3), NO(2), NH(4), PO(4), P-total, K, Ca and Mg) were variable and likely affected by external environmental factors. Copyright © 2012 Elsevier Ltd. All rights reserved.

Driven motion and instability of an atmospheric pressure arc

NASA Astrophysics Data System (ADS)

Karasik, Max

Atmospheric pressure arcs are used extensively in applications such as welding and metallurgy. However, comparatively little is known of the physics of such arcs in external magnetic fields and the mechanisms of the instabilities present. In order to address questions of equilibrium and stability of such arcs, an experimental are furnace is constructed and operated in air with graphite cathode and steel anode at currents 100--250 A. The arc is diagnosed with a gated intensified camera and a collimated photodiode array, as well as fast voltage and current probes. Experiments are carried out on the response of the are to applied transverse DC and AC (up to ≈1 kHz) magnetic fields. The arc is found to deflect parabolically for DC field and assumes a growing sinusoidal structure for AC field. A simple analytic two-parameter fluid model of the are dynamics is derived, in which the inertia of the magnetically pumped cathode jet balances the applied J⃗xB⃗ force. Time variation of the applied field allows evaluation of the parameters individually. A fit of the model to the experimental data gives a value for the average jet speed an order of magnitude below Maecker's estimate of the maximum jet speed. A spontaneous instability of the same arc is investigated experimentally and modeled analytically. The presence of the instability is found to depend critically on cathode dimensions. For cylindrical cathodes, instability occurs only for a narrow range of cathode diameters. Cathode spot motion is proposed as the mechanism of the instability. A simple fluid model combining the effect of the cathode spot motion and the inertia of the cathode jet successfully describes the arc shape during low amplitude instability. The amplitude of cathode spot motion required by the model is in agreement with measurements. The average jet velocity required is approximately equal to that inferred from the transverse magnetic field experiments. Reasons for spot motion and for cathode geometry dependence are discussed. An exploratory study of the instability of the arc in applied axial magnetic field is also described. Applicability of the results of the thesis to an industrial steelmaking furnace is considered.

European external quality control study on the competence of laboratories to recognize rare sequence variants resulting in unusual genotyping results.

PubMed

Márki-Zay, János; Klein, Christoph L; Gancberg, David; Schimmel, Heinz G; Dux, László

2009-04-01

Depending on the method used, rare sequence variants adjacent to the single nucleotide polymorphism (SNP) of interest may cause unusual or erroneous genotyping results. Because such rare variants are known for many genes commonly tested in diagnostic laboratories, we organized a proficiency study to assess their influence on the accuracy of reported laboratory results. Four external quality control materials were processed and sent to 283 laboratories through 3 EQA organizers for analysis of the prothrombin 20210G>A mutation. Two of these quality control materials contained sequence variants introduced by site-directed mutagenesis. One hundred eighty-nine laboratories participated in the study. When samples gave a usual result with the method applied, the error rate was 5.1%. Detailed analysis showed that more than 70% of the failures were reported from only 9 laboratories. Allele-specific amplification-based PCR had a much higher error rate than other methods (18.3% vs 2.9%). The variants 20209C>T and [20175T>G; 20179_20180delAC] resulted in unusual genotyping results in 67 and 85 laboratories, respectively. Eighty-three (54.6%) of these unusual results were not recognized, 32 (21.1%) were attributed to technical issues, and only 37 (24.3%) were recognized as another sequence variant. Our findings revealed that some of the participating laboratories were not able to recognize and correctly interpret unusual genotyping results caused by rare SNPs. Our study indicates that the majority of the failures could be avoided by improved training and careful selection and validation of the methods applied.

Acute cerebellitis successfully managed with temporary cerebrospinal fluid diversion using a long tunnel external ventricular drain: a long-term radiological follow-up of two cases

PubMed Central

Waqas, Muhammad; Hadi, Yousaf Bashir; Sheikh, Sadaf; Shamim, Shahzad M

2016-01-01

Acute cerebellitis (AC) is a rare inflammatory childhood disorder. Although there is no consensus on standard treatment for cerebellitis, its outcome is usually favourable. We report two cases of AC in the paediatric age group, successfully managed with long tunnel external ventricular drain (EVD). The first patient was an 8-year-old boy with a history of fever and headache. Sequential MRI showed diffuse cerebellar swelling with tonsillar herniation and resulting hydrocephalus. The second patient was a 6-month-old boy who presented with high-grade fever associated with chills. CT scan of the head showed triventricular hydrocephalus with obliteration of cerebrospinal fluid spaces and cisterns. Both patients underwent immediate emergency right-sided long tunnel EVD insertion. The EVD was removed on the 9th day in the first patient and the 10th day in the second patient; the patients showed no neurological deficits at a follow-up of 2 years and 1 year, respectively. PMID:27166004

Theory of diatomic molecules in an external electromagnetic field from first quantum mechanical principles.

PubMed

Sindelka, Milan; Moiseyev, Nimrod

2006-04-27

We study a general problem of the translational/rotational/vibrational/electronic dynamics of a diatomic molecule exposed to an interaction with an arbitrary external electromagnetic field. The theory developed in this paper is relevant to a variety of specific applications, such as alignment or orientation of molecules by lasers, trapping of ultracold molecules in optical traps, molecular optics and interferometry, rovibrational spectroscopy of molecules in the presence of intense laser light, or generation of high order harmonics from molecules. Starting from the first quantum mechanical principles, we derive an appropriate molecular Hamiltonian suitable for description of the center of mass, rotational, vibrational, and electronic molecular motions driven by the field within the electric dipole approximation. Consequently, the concept of the Born-Oppenheimer separation between the electronic and the nuclear degrees of freedom in the presence of an electromagnetic field is introduced. Special cases of the dc/ac-field limits are then discussed separately. Finally, we consider a perturbative regime of a weak dc/ac field, and obtain simple analytic formulas for the associated Born-Oppenheimer translational/rotational/vibrational molecular Hamiltonian.

14 CFR 47.15 - Registration number.

Code of Federal Regulations, 2011 CFR

2011-01-01

... REGISTRATION General § 47.15 Registration number. (a) Number required. An applicant for aircraft registration must place a U.S. registration number (registration mark) on the Aircraft Registration Application, AC... Dealer's Aircraft Registration Certificate, AC Form 8050-6, who applies for a temporary registration...

14 CFR 47.15 - Registration number.

Code of Federal Regulations, 2013 CFR

2013-01-01

... REGISTRATION General § 47.15 Registration number. (a) Number required. An applicant for aircraft registration must place a U.S. registration number (registration mark) on the Aircraft Registration Application, AC... Dealer's Aircraft Registration Certificate, AC Form 8050-6, who applies for a temporary registration...

14 CFR 47.15 - Registration number.

Code of Federal Regulations, 2014 CFR

2014-01-01

... REGISTRATION General § 47.15 Registration number. (a) Number required. An applicant for aircraft registration must place a U.S. registration number (registration mark) on the Aircraft Registration Application, AC... Dealer's Aircraft Registration Certificate, AC Form 8050-6, who applies for a temporary registration...

14 CFR 47.15 - Registration number.

Code of Federal Regulations, 2012 CFR

2012-01-01

... REGISTRATION General § 47.15 Registration number. (a) Number required. An applicant for aircraft registration must place a U.S. registration number (registration mark) on the Aircraft Registration Application, AC... Dealer's Aircraft Registration Certificate, AC Form 8050-6, who applies for a temporary registration...

Fluorination effect of activated carbons on performance of asymmetric capacitive deionization

NASA Astrophysics Data System (ADS)

Jo, Hanjoo; Kim, Kyung Hoon; Jung, Min-Jung; Park, Jae Hyun; Lee, Young-Seak

2017-07-01

Activated carbons (ACs) were fluorinated and fabricated into electrodes to investigate the effect of fluorination on asymmetric capacitive deionization (CDI). Fluorine functional groups were introduced on the AC surfaces via fluorination. The specific capacitance of the fluorinated AC (Fsbnd AC) electrode increased drastically from 261 to 337 F/g compared with the untreated AC (Rsbnd AC) electrode at a scan rate of 5 mV/s, despite a decrease in the specific surface area and total pore volume after fluorination. The desalination behavior of asymmetric CDI cells assembled with an Rsbnd AC electrode as the counter electrode and an Fsbnd AC electrode as the cathode (R || F-) or anode (R || F +) was studied. For R || F-, the salt adsorption capacity and charge efficiency increased from 10.6 mg/g and 0.58-12.4 mg/g and 0.75, respectively, compared with the CDI cell assembled with identical Rsbnd AC electrodes at 1 V. This CDI cell exhibited consistently better salt adsorption capacity and charge efficiency at different applied voltages because Fsbnd AC electrodes have a cation attractive effect originating from the partially negatively charged fluorine functional groups on the AC surface. Therefore, co-ion expulsion in the Fsbnd AC electrode as the cathode is effectively diminished, leading to enhanced CDI performance.

Electric Drive Study. Volume 1

DTIC Science & Technology

1987-12-21

CONDITIONER HIGH VOLTAGE DC ICONDITIONER 3 ,300-50 VOLT5), dCONTROL! Figure 5-4. Typical AC Drive System 20 system usable with an induction motor. The...controlling component in an AC drive is the motor power conditioner . This component changes the high voltage DC power to controlled AC power of...selected voltage and frequency which is applied to the drive motors. Since the vehicle gains stored energy as it is accelerated, the motor power conditioner

Electron density dependence of impedance probe plasma potential measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walker, D. N.; Blackwell, D. D.; Amatucci, W. E.

2015-08-15

In earlier works, we used spheres of various sizes as impedance probes in demonstrating a method of determining plasma potential, φ{sub p}, when the probe radius is much larger than the Debye length, λ{sub D}. The basis of the method in those works [Walker et al., Phys. Plasmas 13, 032108 (2006); ibid. 15, 123506 (2008); ibid. 17, 113503 (2010)] relies on applying a small amplitude signal of fixed frequency to a probe in a plasma and, through network analyzer-based measurements, determining the complex reflection coefficient, Γ, for varying probe bias, V{sub b}. The frequency range of the applied signal ismore » restricted to avoid sheath resonant effects and ion contributions such that ω{sub pi} ≪ ω ≪ ω{sub pe}, where ω{sub pi} is the ion plasma frequency and ω{sub pe} is the electron plasma frequency. For a given frequency and applied bias, both Re(Z{sub ac}) and Im(Z{sub ac}) are available from Γ. When Re(Z{sub ac}) is plotted versus V{sub b}, a minimum predicted by theory occurs at φ{sub p} [Walker et al., Phys. Plasmas 17, 113503 (2010)]. In addition, Im(Z{sub ac}) appears at, or very near, a maximum at φ{sub p}. As n{sub e} decreases and the sheath expands, the minimum becomes harder to discern. The purpose of this work is to demonstrate that when using network analyzer-based measurements, Γ itself and Im(Z{sub ac}) and their derivatives are useful as accompanying indicators to Re(Z{sub ac}) in these difficult cases. We note the difficulties encountered by the most commonly used plasma diagnostic, the Langmuir probe. Spherical probe data is mainly used in this work, although we present limited data for a cylinder and a disk. To demonstrate the effect of lowered density as a function of probe geometry, we compare the cylinder and disk using only the indicator Re(Z{sub ac})« less

Influence of electrical fields (AC and DC) on phytoremediation of metal polluted soils with rapeseed (Brassica napus) and tobacco (Nicotiana tabacum).

PubMed

Bi, Ran; Schlaak, Michael; Siefert, Eike; Lord, Richard; Connolly, Helen

2011-04-01

The combined use of electrokinetic remediation and phytoremediation to decontaminate soil polluted with heavy metals has been demonstrated in a laboratory-scale experiment. The plants species selected were rapeseed and tobacco. Three kinds of soil were used: un-contaminated soil from forest area (S1), artificially contaminated soil with 15mgkg(-1) Cd (S2) and multi-contaminated soil with Cd, Zn and Pb from an industrial area (S3). Three treatment conditions were applied to the plants growing in the experimental vessels: control (no electrical field), alternating current electrical field (AC, 1Vcm(-1)) and direct current electrical field (DC, 1Vcm(-1)) with switching polarity every 3h. The electrical fields were applied for 30d for rapeseed and 90d for tobacco, each experiment had three replicates. After a total of 90d growth for rapeseed and of 180d for tobacco, the plants were harvested. The pH variation from anode to cathode was eliminated by switching the polarity of the DC field. The plants reacted differently under the applied electrical field. Rapeseed biomass was enhanced under the AC field and no negative effect was found under DC field. However, no enhancement of the tobacco biomass under the AC treatment was found. The DC field had a negative influence on biomass production on tobacco plants. In general, Cd content was higher in both species growing in S2 treated with AC field compared to the control. Metal uptake (Cd, Cu, Zn and Pb) per rapeseed plant shoot was enhanced by the application of AC field in all soils. Copyright © 2010 Elsevier Ltd. All rights reserved.

RF Power Transfer, Energy Harvesting, and Power Management Strategies

NASA Astrophysics Data System (ADS)

Abouzied, Mohamed Ali Mohamed

Energy harvesting is the way to capture green energy. This can be thought of as a recycling process where energy is converted from one form (here, non-electrical) to another (here, electrical). This is done on the large energy scale as well as low energy scale. The former can enable sustainable operation of facilities, while the latter can have a significant impact on the problems of energy constrained portable applications. Different energy sources can be complementary to one another and combining multiple-source is of great importance. In particular, RF energy harvesting is a natural choice for the portable applications. There are many advantages, such as cordless operation and light-weight. Moreover, the needed infra-structure can possibly be incorporated with wearable and portable devices. RF energy harvesting is an enabling key player for Internet of Things technology. The RF energy harvesting systems consist of external antennas, LC matching networks, RF rectifiers for ac to dc conversion, and sometimes power management. Moreover, combining different energy harvesting sources is essential for robustness and sustainability. Wireless power transfer has recently been applied for battery charging of portable devices. This charging process impacts the daily experience of every human who uses electronic applications. Instead of having many types of cumbersome cords and many different standards while the users are responsible to connect periodically to ac outlets, the new approach is to have the transmitters ready in the near region and can transfer power wirelessly to the devices whenever needed. Wireless power transfer consists of a dc to ac conversion transmitter, coupled inductors between transmitter and receiver, and an ac to dc conversion receiver. Alternative far field operation is still tested for health issues. So, the focus in this study is on near field. The goals of this study are to investigate the possibilities of RF energy harvesting from various sources in the far field, dc energy combining, wireless power transfer in the near field, the underlying power management strategies, and the integration on silicon. This integration is the ultimate goal for cheap solutions to enable the technology for broader use. All systems were designed, implemented and tested to demonstrate proof-of concept prototypes.

Methods for separating medical isotopes using ionic liquids

DOEpatents

Luo, Huimin; Boll, Rose Ann; Bell, Jason Richard; Dai, Sheng

2014-10-21

A method for extracting a radioisotope from an aqueous solution, the method comprising: a) intimately mixing a non-chelating ionic liquid with the aqueous solution to transfer at least a portion of said radioisotope to said non-chelating ionic liquid; and b) separating the non-chelating ionic liquid from the aqueous solution. In preferred embodiments, the method achieves an extraction efficiency of at least 80%, or a separation factor of at least 1.times.10.sup.4 when more than one radioisotope is included in the aqueous solution. In particular embodiments, the method is applied to the separation of medical isotopes pairs, such as Th from Ac (Th-229/Ac-225, Ac-227/Th-227), or Ra from Ac (Ac-225 and Ra-225, Ac-227 and Ra-223), or Ra from Th (Th-227 and Ra-223, Th-229 and Ra-225).

Capacitive Neutralization Dialysis for Direct Energy Generation.

PubMed

Liu, Yue; Zhang, Yi; Ou-Yang, Wei; Bastos Sales, Bruno; Sun, Zhuo; Liu, Fei; Zhao, Ran

2017-08-15

Capacitive neutralization dialysis energy (CNDE) is proposed as a novel energy-harvesting technique that is able to utilize waste acid and alkaline solutions to produce electrical energy. CNDE is a modification based on neutralization dialysis. It was found that a higher NaCl concentration led to a higher open-circuit potential when the concentrations of acid and alkaline solutions were fixed. Upon closing of the circuit, the membrane potential was used as a driving force to move counter ions into the electrical double layers at the electrode-liquid interface, thereby creating an ionic current. Correspondingly, in the external circuit, electrons flow through an external resistor from one electrode to the other, thereby generating electrical energy directly. The influence of external resistances was studied to achieve greater energy extraction, with the maximum output of 110 mW/m 2 obtained by employing an external resistance of 5 Ω together with the AC-coated electrode.

Tapered oral dexamethasone for the acute chest syndrome of sickle cell disease.

PubMed

Quinn, Charles T; Stuart, Marie J; Kesler, Karen; Ataga, Kenneth I; Wang, Winfred C; Styles, Lori; Smith-Whitley, Kim; Wun, Ted; Raj, Ashok; Hsu, Lewis L; Krishnan, Suba; Kuypers, Frans A; Setty, Yamaja; Rhee, Seungshin; Key, Nigel S; Buchanan, George R

2011-10-01

Tapered oral dexamethasone for acute chest syndrome (ACS) in sickle cell anaemia was studied using a novel ACS assessment tool and investigational biomarkers. Twelve participants were randomized (mean age 17·3 years) before early study termination. Dexamethasone decreased duration of hospitalization for ACS by 20·8 h compared to placebo (P = 0·024). Rebound pain occurred in both groups (3 dexamethasone versus 1 placebo). Overall, dexamethasone decreased the leucocyte activation biomarker, sL-selectin; however, participants with rebound pain had higher sL-selectin within 24 h of treatment (dexamethasone or placebo). This ACS assessment tool was feasibly applied, and sL-selectin is a promising biomarker of ACS therapy. © 2011 Blackwell Publishing Ltd.

Automation for Crushing and Screening Equipment to Produce Graded Paving Crushed Stone

NASA Astrophysics Data System (ADS)

Tikhonov, Anatoly; Velichkin, Vladimir

2017-10-01

This paper offers analysis of factors related to production and storage of graded crushed stone, which adversely impact the service life and wear resistance of asphalt-concrete motor road pavements. The paper describes external and technology-related parameters that may cause changes of the preset ratio in graded crushed stone. Control factors are described that ensure the formulated fraction ratio in crushed stone by controlling the operation mode of the crushing and screening equipment. The paper also contains an ACS flow chart for crushing and screening equipment engaged in continuous closed-cycle two-stage technology. Performance of the ACS to maintain the preset fractionated crushed stone ratio has been confirmed with a mathematical model.

[Air conducted ocular VEMP: I. Determination of a method and application in normal patients].

PubMed

Walther, L E; Schaaf, H; Sommer, D; Hörmann, K

2011-07-01

Air conducted (AC) cervical vestibular evoked myogenic potentials (AC cVEMP) and air conducted ocular VEMP (AC oVEMP) may be used for measurement of otolith function. However AC oVEMP are few examined till now. The aim of this pilot study was to apply a method for use of AC oVEMP in clinical practice. AC oVEMP were recorded in healthy voluntary people (n=20) using intense AC-sound stimulation (500 Hz tone bursts, 100 dB nHL). Thermal irrigation and AC cVEMP were normal as including criteria. Values were evaluated statistically. AC oVEMP were recorded in all healthy patients. Mean and standard deviation for the first negative peak was 11.35±1.00 ms and for the first negative peak 16.30±1.10 ms. The mean amplitudes were 7.70±4.50 μV. The stability of n10 and p15 component was the same. AC oVEMP can be easy and fast obtained. N10 and p15 latencies may used as parameter for clinical interpretation. Amplitude fluctuations are relatively large. Results can be used in further clinical investigation of AC oVEMP. © Georg Thieme Verlag KG Stuttgart · New York.

Ion-exchange equilibrium of N-acetyl-D-neuraminic acid on a strong anionic exchanger.

PubMed

Wu, Jinglan; Ke, Xu; Zhang, Xudong; Zhuang, Wei; Zhou, Jingwei; Ying, Hanjie

2015-09-15

N-acetyl-D-neuraminic acid (Neu5Ac) is a high value-added product widely applied in the food industry. A suitable equilibrium model is required for purification of Neu5Ac based on ion-exchange chromatography. Hence, the equilibrium uptake of Neu5Ac on a strong anion exchanger, AD-1 was investigated experimentally and theoretically. The uptake of Neu5Ac by the hydroxyl form of the resin occurred primarily by a stoichiometric exchange of Neu5Ac(-) and OH(-). The experimental data showed that the selectivity coefficient for the exchange of Neu5Ac(-) with OH(-) was a non-constant quantity. Subsequently, the Saunders' model, which took into account the dissociation reactions of Neu5Ac and the condition of electroneutrality, was used to correlate the Neu5Ac sorption isotherms at various solution pHs and Neu5Ac concentrations. The model provided an excellent fit to the binary exchange data for Cl(-)/OH(-) and Neu5Ac(-)/OH(-), and an approximate prediction of equilibrium in the ternary system Cl(-)/Neu5Ac(-)/OH(-). This basic information combined with the general mass transfer model could lay the foundation for the prediction of dynamic behavior of fixed bed separation process afterwards. Copyright © 2015 Elsevier Ltd. All rights reserved.

WATER QUALITY AND TREATMENT CONSIDERATIONS FOR CEMENT-LINED AND A-C PIPE

EPA Science Inventory

Both cement mortar lined (CML) and asbestos-cement pipes (A-C) are widely used in many water systems. Cement linings are also commonly applied in-situ after pipe cleaning, usually to prevent the recurrence of red water or tuberculation problems. Unfortunately, little consideratio...

14 CFR 47.1 - Applicability.

Code of Federal Regulations, 2011 CFR

2011-01-01

... REGISTRATION General § 47.1 Applicability. This part prescribes the requirements for registering aircraft under... Aircraft Registration, AC Form8050-3. Subpart C applies to each applicant for, and holder of, a Dealer's Aircraft Registration Certificate, AC Form 8050-6. [Amdt. 47-29, 75 FR 41979, July 20, 2010] ...

14 CFR 47.1 - Applicability.

Code of Federal Regulations, 2013 CFR

2013-01-01

... REGISTRATION General § 47.1 Applicability. This part prescribes the requirements for registering aircraft under... Aircraft Registration, AC Form8050-3. Subpart C applies to each applicant for, and holder of, a Dealer's Aircraft Registration Certificate, AC Form 8050-6. [Amdt. 47-29, 75 FR 41979, July 20, 2010] ...

14 CFR 47.1 - Applicability.

Code of Federal Regulations, 2012 CFR

2012-01-01

... REGISTRATION General § 47.1 Applicability. This part prescribes the requirements for registering aircraft under... Aircraft Registration, AC Form8050-3. Subpart C applies to each applicant for, and holder of, a Dealer's Aircraft Registration Certificate, AC Form 8050-6. [Amdt. 47-29, 75 FR 41979, July 20, 2010] ...

14 CFR 47.1 - Applicability.

Code of Federal Regulations, 2014 CFR

2014-01-01

... REGISTRATION General § 47.1 Applicability. This part prescribes the requirements for registering aircraft under... Aircraft Registration, AC Form8050-3. Subpart C applies to each applicant for, and holder of, a Dealer's Aircraft Registration Certificate, AC Form 8050-6. [Amdt. 47-29, 75 FR 41979, July 20, 2010] ...

Control analysis for autonomously oscillating biochemical networks.

PubMed Central

Reijenga, Karin A; Westerhoff, Hans V; Kholodenko, Boris N; Snoep, Jacky L

2002-01-01

It has hitherto not been possible to analyze the control of oscillatory dynamic cellular processes in other than qualitative ways. The control coefficients, used in metabolic control analyses of steady states, cannot be applied directly to dynamic systems. We here illustrate a way out of this limitation that uses Fourier transforms to convert the time domain into the stationary frequency domain, and then analyses the control of limit cycle oscillations. In addition to the already known summation theorems for frequency and amplitude, we reveal summation theorems that apply to the control of average value, waveform, and phase differences of the oscillations. The approach is made fully operational in an analysis of yeast glycolytic oscillations. It follows an experimental approach, sampling from the model output and using discrete Fourier transforms of this data set. It quantifies the control of various aspects of the oscillations by the external glucose concentration and by various internal molecular processes. We show that the control of various oscillatory properties is distributed over the system enzymes in ways that differ among those properties. The models that are described in this paper can be accessed on http://jjj.biochem.sun.ac.za. PMID:11751299

Examining Evidence for External and Consequential Validity of the First Term General Chemistry Exam from the ACS Examinations Institute

ERIC Educational Resources Information Center

Lewis, Scott E.

2014-01-01

Validity of educational research instruments and student assessments has appropriately become a growing interest in the chemistry education research community. Of particular concern is an attention to the consequences to students that result from the interpretation of assessment scores and whether those consequences are swayed by invalidity within…

Re-Invigorating Openness at The Open University: The Role of Open Educational Resources

ERIC Educational Resources Information Center

Gourley, Brenda; Lane, Andy

2009-01-01

This paper describes the internal motivations and external drivers that led The Open University UK to enter the field of Open Educational Resources through its institution-wide OpenLearn initiative (www.open.ac.uk/openlearn). It also describes some of the emerging evidence of the impacts inside and outside the university. Through the rapid…

Basic Use of SExtractor Catalogs With TweakR eg - I

NASA Astrophysics Data System (ADS)

Lucas, Ray A.; Hilbert, Bryan

2015-05-01

We describe using external SExtractor (v2.8.6) catalogs from crclean.fits images to align ACS/WFC images with DrizzlePac/TweakReg. Note that this example was originally created before a more recent update to ACS/WFC geometric distortion files. At the time of this writing, one must follow the advice on the ACS Geometric Distortion web page as the first step in the process. By late 2015, as part of OPUS 2015.3, this part will be included by default in the standard pipeline processing and this will no longer need to be manually done by the user. We describe the rest of the process of preparing images for SExtractor, running SExtractor, and using the ouput catalogs to feed to the TweakReg task for alignment, and show that reasonably good first-cut results can be obtained with mostly default parameters in SExtractor and TweakReg. Better results may be possible with more exacting methods. This describes a method for quick alignment, not the ultimate best alignment. Note also that the use of crclean.fits images may be more suited to provide better results for ACS/WFC and WFC3/UVIS than for WFC3/IR.

A method of measuring anterior chamber volume using the anterior segment optical coherence tomographer and specialized software.

PubMed

Wang, Ningli; Wang, Bingsong; Zhai, Gaoshou; Lei, Kun; Wang, Lan; Congdon, Nathan

2007-05-01

To describe and evaluate a new method for measuring anterior chamber volume (ACV). Observational case series. The authors measured ACV using the anterior chamber (AC) optical coherence tomographer (OCT) and applied image-processing software developed by them. Repeatability was evaluated. The ACV was measured in patient groups with normal ACs, shallow ACs, and deep ACs. The volume difference before and after laser peripheral iridotomy (LPI) was analyzed for the shallow and deep groups. Coefficients of repeatability for intraoperator, interoperator, and interimage measurements were 0.406%, 0.958%, and 0.851%, respectively. The limits of agreement for intraoperator and interoperator measurement were -0.911 microl to 1.343 microl and -7.875 microl to -2.463 microl, respectively. There were significant ACV differences in normal, shallow, and deep AC eyes (P < .001) and before and after LPI in shallow AC (P < .001) and deep AC (P = .008) eyes. The ACV values obtained by this method were repeatable and in accord with clinical observation.

DFT modeling, UV-Vis and IR spectroscopic study of acetylacetone-modified zirconia sol-gel materials.

PubMed

Georgieva, Ivelina; Danchova, Nina; Gutzov, Stoyan; Trendafilova, Natasha

2012-06-01

Theoretical and spectroscopic studies of a series of monomeric and dimeric complexes formed through the modification of a zirconium butoxide precursor with acetylacetone and subsequent hydrolysis and/or condensation have been performed by applying DFT/B3LYP/6-31++G(d) and highly accurate RI-ADC(2) methods as well as IR and UV-Vis transmittance and diffuse reflectance spectroscopies. Based on DFT model calculations and simulated and experimental UV-Vis and IR spectra of all the studied structures, the most probable building units of the Zr(IV)-AcAc gel were predicted: the dimeric double hydroxo-bridged complex Zr(2)(AcAc)(2)(OH)(4)(OH)(2br) 9 and the monooxo-bridged complex Zr(2)(AcAc)(2)(OH)(4)O(br)·2H(2)O 12. In both structures, the two AcAc ligands are coordinated to one Zr atom. It was shown that building units 9 and 12 determine the photophysical and vibrational properties of the gel material. The observed UV-Vis and IR spectra of Zr(IV)-AcAc gel were interpreted and a relation between the spectroscopic and structural data was derived. The observed UV-Vis bands at 315 nm and 298/288 nm were assigned to partial ligand-metal transitions and to intra-/inter-AcAc ligand transitions, respectively.

Effect of an alternating current electric field on Co(OH)2 periodic precipitation

NASA Astrophysics Data System (ADS)

Karam, Tony; Sultan, Rabih

2013-02-01

The present paper studies the effect of an alternating current (AC) electric field on Co(OH)2 Liesegang patterns. In the presence of an AC electric field, the band spacing increases with spacing number, but reaches a plateau at large spacing (or band) numbers. The band spacing increases with applied AC voltage, but to a much lesser extent than the effect of a DC electric field under the same applied voltage [see R. Sultan, R. Halabieh, Chem. Phys. Lett. 332 (2000) 331][1]. At low enough applied voltage, the band spacing increases with frequency. At higher voltages, the band spacing becomes independent of the field frequency. The effect of concentration of the inner electrolyte (Co2+), exactly opposes that observed under DC electric field; i.e., the band spacing decreases with increasing concentration. The dynamics were shown to be governed by a competitive scenario between the diffusion gradient and the alternating current electric field factor.

Effect of Statins and Anticoagulants on Prostate Cancer Aggressiveness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alizadeh, Moein; Sylvestre, Marie-Pierre; Zilli, Thomas

2012-07-15

Purpose: Statins and anticoagulants (ACs) have both been associated with a less-aggressive prostate cancer (PCa) and a better outcome after treatment of localized PCa. The results of these studies might have been confounded because patients might often take both medications. We examined their respective influence on PCa aggressiveness at initial diagnosis. Materials and Methods: We analyzed 381 patients treated with either external beam radiotherapy or brachytherapy for low-risk (n = 152), intermediate-risk (n = 142), or high-risk (n = 87) localized PCa. Univariate and multivariate logistic regression analyses were used to investigate an association between these drug classes and prostatemore » cancer aggressiveness. We tested whether the concomitant use of statins and ACs had a different effect than that of either AC or statin use alone. Results: Of the 381 patients, 172 (45.1%) were taking statins and 141 (37.0%) ACs; 105 patients (27.6%) used both. On univariate analysis, the statin and AC users were associated with the prostate-specific antigen (PSA) level (p = .017) and National Comprehensive Cancer Network risk group (p = .0022). On multivariate analysis, statin use was associated with a PSA level <10 ng/mL (odds ratio, 2.9; 95% confidence interval, 1.3-6.8; p = .012) and a PSA level >20 ng/mL (odds ratio, 0.29; 95% confidence interval, 0.08-0.83; p = .03). The use of ACs was associated with a PSA level >20 ng/mL (odds ratio, 0.13; 95% confidence interval, 0.02-0.59, p = .02). Conclusion: Both AC and statins have an effect on PCa aggressiveness, with statins having a more stringent relationship with the PSA level, highlighting the importance of considering statin use in studies of PCa aggressiveness.« less

Non Invasive Sensors for Monitoring the Efficiency of AC Electrical Rotating Machines

PubMed Central

Zidat, Farid; Lecointe, Jean-Philippe; Morganti, Fabrice; Brudny, Jean-François; Jacq, Thierry; Streiff, Frédéric

2010-01-01

This paper presents a non invasive method for estimating the energy efficiency of induction motors used in industrial applications. This method is innovative because it is only based on the measurement of the external field emitted by the motor. The paper describes the sensors used, how they should be placed around the machine in order to decouple the external field components generated by both the air gap flux and the winding end-windings. The study emphasizes the influence of the eddy currents flowing in the yoke frame on the sensor position. A method to estimate the torque from the external field use is proposed. The measurements are transmitted by a wireless module (Zig-Bee) and they are centralized and stored on a PC computer. PMID:22163631

Non invasive sensors for monitoring the efficiency of AC electrical rotating machines.

PubMed

Zidat, Farid; Lecointe, Jean-Philippe; Morganti, Fabrice; Brudny, Jean-François; Jacq, Thierry; Streiff, Frédéric

2010-01-01

This paper presents a non invasive method for estimating the energy efficiency of induction motors used in industrial applications. This method is innovative because it is only based on the measurement of the external field emitted by the motor. The paper describes the sensors used, how they should be placed around the machine in order to decouple the external field components generated by both the air gap flux and the winding end-windings. The study emphasizes the influence of the eddy currents flowing in the yoke frame on the sensor position. A method to estimate the torque from the external field use is proposed. The measurements are transmitted by a wireless module (Zig-Bee) and they are centralized and stored on a PC computer.

Gender- and parity-specific reference charts for fetal size in low risk singleton pregnancies at the onset of the third trimester.

PubMed

De Reu, Paul; Smits, Luc J; Oosterbaan, Herman P; Snijders, Rosalinde J; De Reu-Cuppens, Marga J; Nijhuis, Jan G

2007-01-01

To determine fetal growth in low risk pregnancies at the beginning of the third trimester and to assess the relative importance of fetal gender and maternal parity. Dutch primary care midwifery practice. Retrospective cohort study on 3641 singleton pregnancies seen at a primary care midwifery center in the Netherlands. Parameters used for analysis were fetal abdominal circumference (AC), fetal head circumference (HC), gestational age, fetal gender and maternal parity. Regression analysis was applied to describe variation in AC and HC with gestational age. Means and standard deviations in the present population were compared with commonly used reference charts. Multiple regression analysis was applied to examine whether gender and parity should be taken into account. The fetal AC and HC increased significantly between the 27th and the 33rd week of pregnancy (AC r2=0.3652, P<0.0001; HC r2=0.3301, P<0.0001). Compared to some curves, our means and standard deviations were significantly smaller (at 30+0 weeks AC mean=258+/-13 mm; HC mean=281+/-14 mm), but corresponded well with other curves. Fetal gender was a significant determinant for both AC (P<0.0001) and HC (P<0.0001). Parity contributed significantly to AC only but the difference was small (beta=0.00464). At the beginning of the third trimester, fetal size is associated with fetal gender and, to a lesser extent, with parity. Some fetal growth charts (e.g., Chitty et al.) are more suitable for the low-risk population in the Netherlands than others.

Innovation or rebranding, acute care surgery diffusion will continue.

PubMed

Collins, Courtney E; Pringle, Patricia L; Santry, Heena P

2015-08-01

Patterns of adoption of acute care surgery (ACS) as a strategy for emergency general surgery (EGS) care are unknown. We conducted a qualitative study comprising face-to-face interviews with senior surgeons responsible for ACS at 18 teaching hospitals chosen to ensure diversity of opinions and practice environment (three practice types [community, public or charity, and university] in each of six geographic regions [Mid-Atlantic, Midwest, New England, Northeast, South, and West]). Interviews were recorded, transcribed, and analyzed using NVivo (QSR International, Melbourne, Australia). We applied the methods of investigator triangulation using an inductive approach to develop a final taxonomy of codes organized by themes related to respondents' views on the future of ACS as a strategy for EGS. We applied our findings to a conceptual model on diffusion of innovation. We found a paradox between ACS viewed as a health care delivery innovation versus a rebranding of comprehensive general surgery. Optimism for the future of ACS because of increased desirability for trauma and critical care careers as well as improved EGS outcomes was tempered by fear over lack of continuity, poor institutional resources, and uncertainty regarding financial viability. Our analysis suggests that the implementation of ACS, whether a true health care delivery innovation or an innovative rebranding, fits into the Rogers' diffusion of innovation theory. Despite concerns over resource allocation and the definition of the specialty, from the perspective of senior surgeons deeply entrenched in executing this care delivery model, ACS represents the new face of general surgery that will likely continue to diffuse from these early adopters. Published by Elsevier Inc.

Innovation or rebranding, acute care surgery diffusion will continue

PubMed Central

Collins, Courtney E.; Pringle, Patricia L.; Santry, Heena P.

2015-01-01

Background Patterns of adoption of acute care surgery (ACS) as a strategy for emergency general surgery (EGS) care are unknown. Methods We conducted a qualitative study comprising face-to-face interviews with senior surgeons responsible for ACS at 18 teaching hospitals chosen to ensure diversity of opinions and practice environment (three practice types [community, public/charity, university] in each of six geographic regions [Mid-Atlantic, Midwest, New England, Northeast, South, West]). Interviews were recorded, transcribed, and analyzed using NVivo (QSR International, Melbourne, Australia). We applied the methods of investigator triangulation using an inductive approach to develop a final taxonomy of codes organized by themes related to respondents’ views on the future of ACS as a strategy for EGS. We applied our findings to a conceptual model on diffusion of innovation. Results We found a paradox between ACS viewed as a healthcare delivery innovation versus a rebranding of comprehensive general surgery. Optimism for the future of ACS due to increased desirability for trauma/critical care careers and improved outcomes for EGS was tempered by fear over lack of continuity, poor institutional resources and uncertainty regarding financial viability. Our analysis suggests that the implementation of ACS, whether a true healthcare delivery innovation or an innovative rebranding, fits into the Rogers’ Diffusion of Innovation Theory. Conclusions Despite concerns over resource allocation and the definition of the specialty, from the perspective of senior surgeons deeply entrenched in executing this care-delivery model, ACS represents the new face of general surgery that will likely continue to diffuse from these early adopters. PMID:25891673

Activation and inhibition of adenylyl cyclase isoforms by forskolin analogs.

PubMed

Pinto, Cibele; Papa, Dan; Hübner, Melanie; Mou, Tung-Chung; Lushington, Gerald H; Seifert, Roland

2008-04-01

Adenylyl cyclase (AC) isoforms 1 to 9 are differentially expressed in tissues and constitute an interesting drug target. ACs 1 to 8 are activated by the diterpene, forskolin (FS). It is unfortunate that there is a paucity of AC isoform-selective activators. To develop such compounds, an understanding of the structure/activity relationships of diterpenes is necessary. Therefore, we examined the effects of FS and nine FS analogs on ACs 1, 2, and 5 expressed in Spodoptera frugiperda insect cells. Diterpenes showed the highest potencies at AC1 and the lowest potencies at AC2. We identified full agonists, partial agonists, antagonists, and inverse agonists, i.e., diterpenes that reduced basal AC activity. Each AC isoform exhibited a distinct pharmacological profile. AC2 showed the highest basal activity of all AC isoforms and highest sensitivity to inverse agonistic effects of 1-deoxy-forskolin, 7-deacetyl-1,9-dideoxy-forskolin, and, particularly, BODIPY-forskolin. In contrast, BODIPY-forskolin acted as partial agonist at the other ACs. 1-Deoxy-forskolin analogs were devoid of agonistic activity at ACs but antagonized the effects of FS in a mixed competitive/noncompetitive manner. At purified catalytic AC subunits, BODIPY-forskolin acted as weak partial agonist/strong partial antagonist. Molecular modeling revealed that the BODIPY group rotates promiscuously outside of the FS-binding site. Collectively, ACs are not uniformly activated and inhibited by FS and FS analogs, demonstrating the feasibility to design isoform-selective FS analogs. The two- and multiple-state models, originally developed to conceptualize ligand effects at G-protein-coupled receptors, can be applied to ACs to explain certain experimental data.

Failure detection and recovery in the assembly/contingency subsystem

NASA Technical Reports Server (NTRS)

Gantenbein, Rex E.

1993-01-01

The Assembly/Contingency Subsystem (ACS) is the primary communications link on board the Space Station. Any failure in a component of this system or in the external devices through which it communicates with ground-based systems will isolate the Station. The ACS software design includes a failure management capability (ACFM) that provides protocols for failure detection, isolation, and recovery (FDIR). The the ACFM design requirements as outlined in the current ACS software requirements specification document are reviewed. The activities carried out in this review include: (1) an informal, but thorough, end-to-end failure mode and effects analysis of the proposed software architecture for the ACFM; and (2) a prototype of the ACFM software, implemented as a C program under the UNIX operating system. The purpose of this review is to evaluate the FDIR protocols specified in the ACS design and the specifications themselves in light of their use in implementing the ACFM. The basis of failure detection in the ACFM is the loss of signal between the ground and the Station, which (under the appropriate circumstances) will initiate recovery to restore communications. This recovery involves the reconfiguration of the ACS to either a backup set of components or to a degraded communications mode. The initiation of recovery depends largely on the criticality of the failure mode, which is defined by tables in the ACFM and can be modified to provide a measure of flexibility in recovery procedures.

Certain applied electrical signals during EPG cause negative effects on stylet probing behaviors by adult Lygus lineolaris (Hemiptera: Miridae).

PubMed

Backus, Elaine A; Cervantes, Felix A; Godfrey, Larry; Akbar, Waseem; Clark, Thomas L; Rojas, Maria G

This study is the first to fully evaluate whether electrical signals applied to large insects during electropenetrography (EPG; also called electrical penetration graph) negatively affect insect behavior. During EPG, electrical signals are applied to plants, and thus to the gold-wire-tethered insects feeding on them. The insect completes an electrical circuit whose changes in voltage reflect the insect's stylet probing/penetration behaviors, recorded as waveform output. For nearly 50 years of EPG science, evidence has supported that there are no or negligible effects on tiny insects from applied electricity during EPG. Recently however, EPG studies of large-bodied hemipterans such as heteropterans and sharpshooter leafhoppers have been published. The wider stylet diameters of such large insects cause them to have lower inherent resistances to applied signals compared with smaller insects, conveying more electrical current. The present study asked whether such increased currents would affect insect stylet probing, by comparing Lygus lineolaris behaviors on pin-head cotton squares using an AC-DC electropenetrograph. Effects of AC or DC applied signals were separately examined in two factorial studies, each comparing four input resistor (Ri) levels (10 6 , 10 7 , 10 8 and 10 9  Ω) and four applied voltage levels (2, 60, 150 and 250 mV). Results showed that changes in both probing and non-probing behaviors were indeed caused by changing signal type, Ri level, or applied voltage. Negative effects on feeding were numerically greater overall for DC than AC applied signals, perhaps due to muscular tetany from DC; however, AC versus DC could not be statistically tested. Results strongly support the need for flexible Ri and applied voltage levels and types, to tailor instrument settings to the size and special needs of each insect subject. Our findings will facilitate further EPG studies of Lygus spp., such as host plant resistance or insecticidal assays/bioassays to assess mode of action and appropriate dosage. It is hoped that this study will also inform EPG studies of similar, large heteropterans in the future. Published by Elsevier Ltd.

Modeling of material erosion and redeposition for dedicated DiMES experiments on DIII-D

NASA Astrophysics Data System (ADS)

Ding, R.; Abrams, T.; Chrobak, C. P.; Guo, H. Y.; Snyder, P. B.; Chan, V. S.; Rudakov, D. L.; Stangeby, P. C.; Elder, J. D.; Tskhakaya, D.; Wampler, W. R.; Kirschner, A.; McLean, A. G.

2015-11-01

Erosion and redeposition of plasma facing materials is a key issue for high-power, long pulse tokamak operation. A series of experiments has been carried out on DIII-D in which well-characterized samples of different materials were exposed to divertor plasma using DiMES. Such experiments provide a good benchmark for PMI codes, such as ERO. It was found that the erosion and redeposition are strongly determined by the impurity content in the plasma and sheath properties near the surface. The principal experimental results (net erosion rate and profile, net/gross erosion ratio) are reproduced by ERO simulations to within the uncertainties, indicating that the controlling physics has likely been identified. New techniques suggested by modeling such as external biasing and local gas injection for suppressing material erosion are planned to be tested in DiMES/DIII-D experiments. Work supported by US DOE DE-FC02-04ER54698, DE-AC52-07NA27344, DE-AC04-94AL85000, DE-AC52-07NA27344.

Synthetic tactile perception induced by transcranial alternating-current stimulation can substitute for natural sensory stimulus in behaving rabbits.

PubMed

Márquez-Ruiz, Javier; Ammann, Claudia; Leal-Campanario, Rocío; Ruffini, Giulio; Gruart, Agnès; Delgado-García, José M

2016-01-21

The use of brain-derived signals for controlling external devices has long attracted the attention from neuroscientists and engineers during last decades. Although much effort has been dedicated to establishing effective brain-to-computer communication, computer-to-brain communication feedback for "closing the loop" is now becoming a major research theme. While intracortical microstimulation of the sensory cortex has already been successfully used for this purpose, its future application in humans partly relies on the use of non-invasive brain stimulation technologies. In the present study, we explore the potential use of transcranial alternating-current stimulation (tACS) for synthetic tactile perception in alert behaving animals. More specifically, we determined the effects of tACS on sensory local field potentials (LFPs) and motor output and tested its capability for inducing tactile perception using classical eyeblink conditioning in the behaving animal. We demonstrated that tACS of the primary somatosensory cortex vibrissa area could indeed substitute natural stimuli during training in the associative learning paradigm.

Spin pumping and inverse spin Hall voltages from dynamical antiferromagnets

NASA Astrophysics Data System (ADS)

Johansen, Øyvind; Brataas, Arne

2017-06-01

Dynamical antiferromagnets can pump spins into adjacent conductors. The high antiferromagnetic resonance frequencies represent a challenge for experimental detection, but magnetic fields can reduce these resonance frequencies. We compute the ac and dc inverse spin Hall voltages resulting from dynamical spin excitations as a function of a magnetic field along the easy axis and the polarization of the driving ac magnetic field perpendicular to the easy axis. We consider the insulating antiferromagnets MnF2,FeF2, and NiO. Near the spin-flop transition, there is a significant enhancement of the dc spin pumping and inverse spin Hall voltage for the uniaxial antiferromagnets MnF2 and FeF2. In the uniaxial antiferromagnets it is also found that the ac spin pumping is independent of the external magnetic field when the driving field has the optimal circular polarization. In the biaxial NiO, the voltages are much weaker, and there is no spin-flop enhancement of the dc component.

Spectral embedding based active contour (SEAC) for lesion segmentation on breast dynamic contrast enhanced magnetic resonance imaging.

PubMed

Agner, Shannon C; Xu, Jun; Madabhushi, Anant

2013-03-01

Segmentation of breast lesions on dynamic contrast enhanced (DCE) magnetic resonance imaging (MRI) is the first step in lesion diagnosis in a computer-aided diagnosis framework. Because manual segmentation of such lesions is both time consuming and highly susceptible to human error and issues of reproducibility, an automated lesion segmentation method is highly desirable. Traditional automated image segmentation methods such as boundary-based active contour (AC) models require a strong gradient at the lesion boundary. Even when region-based terms are introduced to an AC model, grayscale image intensities often do not allow for clear definition of foreground and background region statistics. Thus, there is a need to find alternative image representations that might provide (1) strong gradients at the margin of the object of interest (OOI); and (2) larger separation between intensity distributions and region statistics for the foreground and background, which are necessary to halt evolution of the AC model upon reaching the border of the OOI. In this paper, the authors introduce a spectral embedding (SE) based AC (SEAC) for lesion segmentation on breast DCE-MRI. SE, a nonlinear dimensionality reduction scheme, is applied to the DCE time series in a voxelwise fashion to reduce several time point images to a single parametric image where every voxel is characterized by the three dominant eigenvectors. This parametric eigenvector image (PrEIm) representation allows for better capture of image region statistics and stronger gradients for use with a hybrid AC model, which is driven by both boundary and region information. They compare SEAC to ACs that employ fuzzy c-means (FCM) and principal component analysis (PCA) as alternative image representations. Segmentation performance was evaluated by boundary and region metrics as well as comparing lesion classification using morphological features from SEAC, PCA+AC, and FCM+AC. On a cohort of 50 breast DCE-MRI studies, PrEIm yielded overall better region and boundary-based statistics compared to the original DCE-MR image, FCM, and PCA based image representations. Additionally, SEAC outperformed a hybrid AC applied to both PCA and FCM image representations. Mean dice similarity coefficient (DSC) for SEAC was significantly better (DSC = 0.74 ± 0.21) than FCM+AC (DSC = 0.50 ± 0.32) and similar to PCA+AC (DSC = 0.73 ± 0.22). Boundary-based metrics of mean absolute difference and Hausdorff distance followed the same trends. Of the automated segmentation methods, breast lesion classification based on morphologic features derived from SEAC segmentation using a support vector machine classifier also performed better (AUC = 0.67 ± 0.05; p < 0.05) than FCM+AC (AUC = 0.50 ± 0.07), and PCA+AC (AUC = 0.49 ± 0.07). In this work, we presented SEAC, an accurate, general purpose AC segmentation tool that could be applied to any imaging domain that employs time series data. SE allows for projection of time series data into a PrEIm representation so that every voxel is characterized by the dominant eigenvectors, capturing the global and local time-intensity curve similarities in the data. This PrEIm allows for the calculation of strong tensor gradients and better region statistics than the original image intensities or alternative image representations such as PCA and FCM. The PrEIm also allows for building a more accurate hybrid AC scheme.

Comparative study of 0° X-cut and Y + 36°-cut lithium niobate high-voltage sensing

NASA Astrophysics Data System (ADS)

Patel, N.; Branch, D. W.; Schamiloglu, E.; Cular, S.

2015-08-01

A comparison study between Y + 36° and 0° X-cut lithium niobate (LiNbO3) was performed to evaluate the influence of crystal cut on the acoustic propagation to realize a piezoelectric high-voltage sensor. The acoustic time-of-flight for each crystal cut was measured when applying direct current (DC), alternating current (AC), and pulsed voltages. Results show that the voltage-induced shift in the acoustic wave propagation time scaled quadratically with voltage for DC and AC voltages applied to X-cut crystals. For the Y + 36° crystal, the voltage-induced shift scales linearly with DC voltages and quadratically with AC voltages. When applying 5 μs voltage pulses to both crystals, the voltage-induced shift scaled linearly with voltage. For the Y + 36° cut, the voltage-induced shift from applying DC voltages ranged from 10 to 54 ps and 35 to 778 ps for AC voltages at 640 V over the frequency range of 100 Hz-100 kHz. Using the same conditions as the Y + 36° cut, the 0° X-cut crystal sensed a shift of 10-273 ps for DC voltages and 189-813 ps for AC voltage application. For 5 μs voltage pulses, the 0° X-cut crystal sensed a voltage induced shift of 0.250-2 ns and the Y + 36°-cut crystal sensed a time shift of 0.115-1.6 ns. This suggests a frequency sensitive response to voltage where the influence of the crystal cut was not a significant contributor under DC, AC, or pulsed voltage conditions. The measured DC data were compared to a 1-D impedance matrix model where the predicted incremental length changed as a function of voltage. When the voltage source error was eliminated through physical modeling from the uncertainty budget, the combined uncertainty of the sensor (within a 95% confidence interval) decreased to 0.0033% using a Y + 36°-cut crystal and 0.0032% using an X-cut crystal for all the voltage conditions used in this experiment.

Comparative study of 0° X-cut and Y + 36°-cut lithium niobate high-voltage sensing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, N.; Department of Electrical and Computer Engineering, MSC01 1100, University of New Mexico, Albuquerque, New Mexico 87131-0001; Branch, D. W.

2015-08-15

A comparison study between Y + 36° and 0° X-cut lithium niobate (LiNbO{sub 3}) was performed to evaluate the influence of crystal cut on the acoustic propagation to realize a piezoelectric high-voltage sensor. The acoustic time-of-flight for each crystal cut was measured when applying direct current (DC), alternating current (AC), and pulsed voltages. Results show that the voltage-induced shift in the acoustic wave propagation time scaled quadratically with voltage for DC and AC voltages applied to X-cut crystals. For the Y + 36° crystal, the voltage-induced shift scales linearly with DC voltages and quadratically with AC voltages. When applying 5more » μs voltage pulses to both crystals, the voltage-induced shift scaled linearly with voltage. For the Y + 36° cut, the voltage-induced shift from applying DC voltages ranged from 10 to 54 ps and 35 to 778 ps for AC voltages at 640 V over the frequency range of 100 Hz–100 kHz. Using the same conditions as the Y + 36° cut, the 0° X-cut crystal sensed a shift of 10–273 ps for DC voltages and 189–813 ps for AC voltage application. For 5 μs voltage pulses, the 0° X-cut crystal sensed a voltage induced shift of 0.250–2 ns and the Y + 36°-cut crystal sensed a time shift of 0.115–1.6 ns. This suggests a frequency sensitive response to voltage where the influence of the crystal cut was not a significant contributor under DC, AC, or pulsed voltage conditions. The measured DC data were compared to a 1-D impedance matrix model where the predicted incremental length changed as a function of voltage. When the voltage source error was eliminated through physical modeling from the uncertainty budget, the combined uncertainty of the sensor (within a 95% confidence interval) decreased to 0.0033% using a Y + 36°-cut crystal and 0.0032% using an X-cut crystal for all the voltage conditions used in this experiment.« less

Comparative study of 0° X-cut and Y+36°-cut lithium niobate high-voltage sensing

DOE PAGES

Patel, N.; Branch, D. W.; Schamiloglu, E.; ...

2015-08-11

A comparison study between Y+36° and 0° X-cut lithium niobate (LiNbO 3) was performed to evaluate the influence of crystal cut on the acoustic propagation to realize a piezoelectric high-voltage sensor. The acoustic time-of-flight for each crystal cut was measured when applying direct current (DC), alternating current (AC), and pulsed voltages. Results show that the voltage-induced shift in the acoustic wave propagation time scaled quadratically with voltage for DC and AC voltages applied to X-cut crystals. For the Y+36° crystal, the voltage-induced shift scales linearly with DC voltages and quadratically with AC voltages. When applying 5 μs voltage pulses tomore » both crystals, the voltage-induced shift scaled linearly with voltage. For the Y+36° cut, the voltage-induced shift from applying DC voltages ranged from 10 to 54 ps and 35 to 778 ps for AC voltages at 640 V over the frequency range of 100 Hz–100 kHz. Using the same conditions as the Y+36° cut, the 0° X-cut crystal sensed a shift of 10–273 ps for DC voltages and 189–813 ps for AC voltage application. For 5 μs voltage pulses, the 0° X-cut crystal sensed a voltage induced shift of 0.250–2 ns and the Y+36°-cut crystal sensed a time shift of 0.115–1.6 ns. This suggests a frequency sensitive response to voltage where the influence of the crystal cut was not a significant contributor under DC, AC, or pulsed voltage conditions. The measured DC data were compared to a 1-D impedance matrix model where the predicted incremental length changed as a function of voltage. Furthermore, when the voltage source error was eliminated through physical modeling from the uncertainty budget, the combined uncertainty of the sensor (within a 95% confidence interval) decreased to 0.0033% using a Y + 36°-cut crystal and 0.0032% using an X-cut crystal for all the voltage conditions used in this experiment.« less

Method and system for an on-chip AC self-test controller

DOEpatents

Flanagan, John D [Rhinebeck, NY; Herring, Jay R [Poughkeepsie, NY; Lo, Tin-Chee [Fishkill, NY

2008-09-30

A method and system for performing AC self-test on an integrated circuit that includes a system clock for use during normal operation are provided. The method includes applying a long data capture pulse to a first test register in response to the system clock, applying an at speed data launch pulse to the first test register in response to the system clock, inputting the data from the first register to a logic path in response to applying the at speed data launch pulse to the first test register, applying an at speed data capture pulse to a second test register in response to the system clock, inputting the logic path output to the second test register in response to applying the at speed data capture pulse to the second test register, and applying a long data launch pulse to the second test register in response to the system clock.

Method and system for an on-chip AC self-test controller

DOEpatents

Flanagan, John D.; Herring, Jay R.; Lo, Tin-Chee

2006-06-06

A method for performing AC self-test on an integrated circuit, including a system clock for use during normal operation. The method includes applying a long data capture pulse to a first test register in response to the system clock, and further applying at an speed data launch pulse to the first test register in response to the system clock. Inputting the data from the first register to a logic path in response to applying the at speed data launch pulse to the first test register. Applying at speed data capture pulse to a second test register in response to the system clock. Inputting the output from the logic path to the second test register in response to applying the at speed data capture pulse to the second register. Applying a long data launch pulse to the second test register in response to the system clock.

Novel method for immunofluorescence staining of mammalian eggs using non-contact alternating-current electric-field mixing of microdroplets

PubMed Central

Hiromitsu, Shirasawa; Jin, Kumagai; Emiko, Sato; Katsuya, Kabashima; Yukiyo, Kumazawa; Wataru, Sato; Hiroshi, Miura; Ryuta, Nakamura; Hiroshi, Nanjo; Yoshihiro, Minamiya; Yoichi, Akagami; Yukihiro, Terada

2015-01-01

Recently, a new technique was developed for non-catalytically mixing microdroplets. In this method, an alternating-current (AC) electric field is used to promote the antigen–antibody reaction within the microdroplet. Previously, this technique has only been applied to histological examinations of flat structures, such as surgical specimens. In this study, we applied this technique for the first time to immunofluorescence staining of three-dimensional structures, specifically, mammalian eggs. We diluted an antibody against microtubules from 1:1,000 to 1:16,000, and compared the chromatic degree and extent of fading across dilutions. In addition, we varied the frequency of AC electric-field mixing from 5 Hz to 46 Hz and evaluated the effect on microtubule staining. Microtubules were more strongly stained after AC electric-field mixing for only 5 minutes, even when the concentration of primary antibody was 10 times lower than in conventional methods. AC electric-field mixing also alleviated microtubule fading. At all frequencies tested, AC electric-field mixing resulted in stronger microtubule staining than in controls. There was no clear difference in a microtubule staining between frequencies. These results suggest that the novel method could reduce antibody consumption and shorten immunofluorescence staining time. PMID:26477850

Modelling ac ripple currents in HTS coated conductors

NASA Astrophysics Data System (ADS)

Xu, Zhihan; Grilli, Francesco

2015-10-01

Dc transmission using high temperature superconducting (HTS) coated conductors (CCs) offers a promising solution to the globally growing demand for effective, reliable and economic transmission of green energy up to the gigawatt level over very long distances. The credible estimation of the losses and thereby the heat dissipation involved, where ac ripples (introduced in rectification/ac-dc conversion) are viewed as a potential source of notable contribution, is highly essential for the rational design of practical HTS dc transmission cables and corresponding cryogenic systems to fulfil this demand. Here we report a targeted modelling study into the ac losses in a HTS CC subject to dc and ac ripple currents simultaneously, by solving Maxwell’s equations using the finite element method (FEM) in the commercial software package COMSOL. It is observed that the instantaneous loss exhibits only one peak per cycle in the HTS CC subject to sinusoidal ripples, given that the amplitude of the ac ripples is smaller than approximately 20% of that of the dc current. This is a distinct contrast to the usual observation of two peaks per cycle in a HTS CC subject to ac currents only. The unique mechanism is also revealed, which is directly associated with the finding that, around any local minima of the applied ac ripples, the critical state of -J c is never reached at the edges of the HTS CC, as it should be according to the Bean model. When running further into the longer term, it is discovered that the ac ripple loss of the HTS CC in full-wave rectification decays monotonically, at a speed which is found to be insensitive to the frequency of the applied ripples within our targeted situations, to a relatively low level of approximately 1.38 × 10-4 W m-1 in around 1.7 s. Comparison between this level and other typical loss contributions in a HTS dc cable implies that ac ripple currents in HTS CCs should only be considered as a minor source of dissipation in superconducting dc transmission.

Environmental Fate Model for Ultra-Low-Volume Insecticide Applications Used for Adult Mosquito Management

DTIC Science & Technology

2012-01-01

h. Applica- tions occurred when the prevailing wind was blowing perpendicular to the collection site (Fig. 1). Sprays were conducted using a Guardian...min. Permanone 30–30 was mixed 1:2:1 with Crystal Plus 70 T light mineral oil (STE Oil Company, Inc., San Marcos, TX, USA) and ACS grade toluene and...applied at a flow rate of 192 ml/min. Scourge 18+54wasmixed at 1:0.4:0.4with Crystal Plus 70 T light mineral oil and ACS grade toluene and applied at a

Acromioclavicular joint dislocations: coracoclavicular reconstruction with and without additional direct acromioclavicular repair.

PubMed

Weiser, Lukas; Nüchtern, Jakob V; Sellenschloh, Kay; Püschel, Klaus; Morlock, Michael M; Rueger, Johannes M; Hoffmann, Michael; Lehmann, Wolfgang; Großterlinden, Lars G

2017-07-01

To evaluate different stabilisation techniques for acromioclavicular (AC) joint separations, including direct AC repair, and to compare the properties of the stabilised and native joints. An established in vitro testing model for the AC joint was used to analyse joint stability after surgical reconstruction [double TightRope (DTR), DTR with AC repair (DTR + AC), single TR with AC repair (TR + AC), and PDS sling with AC repair (PDS + AC)]. Twenty-four human cadaveric shoulders were randomised by age into four testing groups. Joint stiffness was measured by applying an axial load during defined physiological ranges of motion. Similar tests were performed for the native joints, after dissecting the coracoclavicular and AC ligaments, and after surgical reconstruction. Cyclic loading was performed for 1000 cycles with 20-70 N and vertical load to failure determined after cyclic testing. Axial stiffness for all TR groups was significantly higher than for the native joint (DTR 38.94 N/mm, p = 0.005; DTR + AC 37.79 N/mm, p = 0.015; TR + AC 45.61 N/mm, p < 0.001 vs. native 26.05 N/mm). The axial stiffness of the PDS + AC group was similar to that of the native joint group (21.4 N/mm, n.s.). AC repair did not significantly influence rotational stiffness. Load to failure was similar and >600 N in all groups (n.s.). Reconstruction of AC dislocations with one or two TRs leads to stable results with a higher stiffness than the native joints. For the PDS + AC group, axial stiffness was similar to the native situation, although there might be a risk of elongation. Direct AC repair showed no significantly increased stability in comparison with reconstructions without direct AC repair. Thus, a direct AC repair seems to be dispensable in clinical practice, while TRs or PDS cerclages appear to provide sufficiently stable results.

Current management of hyperglycemia in acute coronary syndromes: a national Dutch survey.

PubMed

de Mulder, Maarten; Oemrawsingh, Rohit M; Stam, Frank; Boersma, Eric; Umans, Victor A W M

2009-06-01

Hyperglycemia is common among patients admitted with acute coronary syndromes (ACS) and is associated with less favorable clinical outcomes. Guidelines for the treatment of hyperglycemia in myocardial infarction are confusing, partly because of lack of sufficient evidence. Neither do we know what the everyday practice on hyperglycemia in ACS is. Therefore the aim of our study is to describe current glucose management in ACS patients in The Netherlands. We designed a multiple-choice questionnaire that was emailed to all 94 independent cardiology departments of each of the 114 hospitals within The Netherlands. We interviewed cardiologists about their specific hospital setting, the presence, content, and actual use of a dedicated hyperglycemia protocol in the setting of ACS. Ninety-four questionnaires were returned (response rate 100%). Only 32% of the respondents reported to have a routinely applied, dedicated hyperglycemia protocol in the setting of ACS. An admission glucose of 13.0 mmol/L is considered a stress value by 60% of respondents. Treatment of hyperglycemia is postponed until after the acute phase (ie, after >6 hours) in 41% of the cardiology departments and in 76% HbA1c is not routinely measured before discharge. Only a minority of Dutch cardiology departments have a routinely applied, dedicated hyperglycemia protocol for patients admitted with ACS. Different views exist on the interpretation of admission hyperglycemia in patients without previously diagnosed diabetes. Dedicated protocols with well-established treatment goals allow early treatment and are mandatory to improve timely metabolic regulation.

Off-resonance energy absorption in a linear Paul trap due to mass selective resonant quenching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivarajah, I.; Goodman, D. S.; Wells, J. E.

Linear Paul traps (LPT) are used in many experimental studies such as mass spectrometry, atom-ion collisions, and ion-molecule reactions. Mass selective resonant quenching (MSRQ) is implemented in LPT either to identify a charged particle's mass or to remove unwanted ions from a controlled experimental environment. In the latter case, MSRQ can introduce undesired heating to co-trapped ions of different mass, whose secular motion is off resonance with the quenching ac field, which we call off-resonance energy absorption (OREA). We present simulations and experimental evidence that show that the OREA increases exponentially with the number of ions loaded into the trapmore » and with the amplitude of the off-resonance external ac field.« less

Current level detector

DOEpatents

Kerns, Cordon R.

1977-01-01

A device is provided for detecting the current level of a DC signal. It includes an even harmonic modulator to which a reference AC signal is applied. The unknown DC signal acts on the reference AC signal so that the output of the modulator includes an even harmonic whose amplitude is proportional to the unknown DC current.

Using the US EPA's CompTox Dashboard to support identification and screening of emerging organic contaminants in the environment (ACS Spring National meeting) 2 of 7

EPA Science Inventory

The US EPA’s iCSS CompTox Dashboard is a curated, publicly accessible resource provided by the National Center for Computational Toxicology (https://comptox.epa.gov). The Dashboard provides support for toxicology and risk assessment within and external to the EPA (including ToxC...

Transverse ac-driven and geometric ratchet effects for vortices in conformal crystal pinning arrays

DOE PAGES

Reichhardt, Charles; Reichhardt, Cynthia Jane Olsen

2016-02-11

A conformal pinning array is created by taking a conformal transformation of a uniform hexagonal lattice to create a structure in which the sixfold ordering of the original lattice is preserved but which has a spatial gradient in the pinning site density. With a series of conformal arrays it is possible to create asymmetric substrates, and it was previously shown that when an ac drive is applied parallel to the asymmetry direction, a pronounced ratchet effect occurs with a net dc flow of vortices in the same direction as the ac drive. Here, in this article, we show that whenmore » the ac drive is applied perpendicular to the substrate asymmetry direction, it is possible to realize a transverse ratchet effect where a net dc flow of vortices is generated perpendicular to the ac drive. The conformal transverse ratchet effect is distinct from previous versions of transverse ratchets in that it occurs due to the generation of non-Gaussian transverse vortex velocity fluctuations by the plastic motion of vortices, so that the system behaves as a noise correlation ratchet. The transverse ratchet effect is much more pronounced in the conformal arrays than in random gradient arrays and is absent in square gradient arrays due the different nature of the vortex flow in each geometry. We show that a series of reversals can occur in the transverse ratchet effect due to changes in the vortex flow across the pinning gradient as a function of vortex filling, pinning strength, and ac amplitude. We also consider the case where a dc drive applied perpendicular to the substrate asymmetry direction generates a net flow of vortices perpendicular to the dc drive, producing what is known as a geometric or drift ratchet that again arises due to non-Gaussian dynamically generated fluctuations. The drift ratchet is more efficient than the ac driven ratchet and also exhibits a series of reversals for varied parameters. Lastly, our results should be general to a wide class of systems undergoing nonequilibrium dynamics on conformal substrates, such as colloidal particles on optical traps.« less

Electric-field driven assembly of live bacterial cell microarrays for rapid phenotypic assessment and cell viability testing.

PubMed

Goel, Meenal; Verma, Abhishek; Gupta, Shalini

2018-07-15

Microarray technology to isolate living cells using external fields is a facile way to do phenotypic analysis at the cellular level. We have used alternating current dielectrophoresis (AC-DEP) to drive the assembly of live pathogenic Salmonella typhi (S.typhi) and Escherichia coli (E.coli) bacteria into miniaturized single cell microarrays. The effects of voltage and frequency were optimized to identify the conditions for maximum cell capture which gave an entrapment efficiency of 90% in 60 min. The chip was used for calibration-free estimation of cellular loads in binary mixtures and further applied for rapid and enhanced testing of cell viability in the presence of drug via impedance spectroscopy. Our results using a model antimicrobial sushi peptide showed that the cell viability could be tested down to 5 μg/mL drug concentration under an hour, thus establishing the utility of our system for ultrafast and sensitive detection. Copyright © 2018 Elsevier B.V. All rights reserved.

Magnetic Control of Locked Modes in Present Devices and ITER

NASA Astrophysics Data System (ADS)

Volpe, F. A.; Sabbagh, S.; Sweeney, R.; Hender, T.; Kirk, A.; La Haye, R. J.; Strait, E. J.; Ding, Y. H.; Rao, B.; Fietz, S.; Maraschek, M.; Frassinetti, L.; in, Y.; Jeon, Y.; Sakakihara, S.

2014-10-01

The toroidal phase of non-rotating (``locked'') neoclassical tearing modes was controlled in several devices by means of applied magnetic perturbations. Evidence is presented from various tokamaks (ASDEX Upgrade, DIII-D, JET, J-TEXT, KSTAR), spherical tori (MAST, NSTX) and a reversed field pinch (EXTRAP-T2R). Furthermore, the phase of interchange modes was controlled in the LHD helical device. These results share a common interpretation in terms of torques acting on the mode. Based on this interpretation, it is predicted that control-coil currents will be sufficient to control the phase of locking in ITER. This will be possible both with the internal coils and with the external error-field-correction coils, and might have promising consequences for disruption avoidance (by aiding the electron cyclotron current drive stabilization of locked modes), as well as for spatially distributing heat loads during disruptions. This work was supported in part by the US Department of Energy under DE-SC0008520, DE-FC-02-04ER54698 and DE-AC02-09CH11466.

Neutral atom traps of rare isotopes

NASA Astrophysics Data System (ADS)

Mueller, Peter

2016-09-01

Laser cooling and trapping techniques offer exquisite control of an atom's external and internal degrees of freedom. The species of interest can be selectively captured, cooled close to absolute zero temperatures, and observed with high signal-to-noise ratio. Moreover, the atom's electronic and magnetic state populations can be precisely manipulated and interrogated. Applied in nuclear physics, these techniques are ideal for precision measurements in the fields of fundamental interactions and symmetries, nuclear structure studies, and isotopic trace analysis. In particular, they offer unique opportunities in the quest for physics beyond the standard model. I will shortly review the basics of this approach and the state of the field and then cover in more details recent results from two such efforts: the search for a permanent electric dipole moment in 225Ra and the beta-neutrino angular correlation measurement with laser trapped 6He. This work is supported by the U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract DE-AC02-06CH11357.

Theory of interaction-induced renormalization of Drude weight and plasmon frequency in chiral multilayer graphene

NASA Astrophysics Data System (ADS)

Li, Xiao; Tse, Wang-Kong

2017-02-01

We develop a theory for the optical conductivity of doped ABC-stacked multilayer graphene including the effects of electron-electron interactions. Applying the quantum kinetic formalism, we formulate a set of pseudospin Bloch equations that govern the dynamics of the nonequilibrium density matrix driven by an external ac electric field under the influence of Coulomb interactions. These equations reveal a dynamical mechanism that couples the Drude and interband responses arising from the chirality of pseudospin textures in multilayer graphene systems. We demonstrate that this results in an interaction-induced enhancement of the Drude weight and plasmon frequency strongly dependent on the pseudospin winding number. Using bilayer graphene as an example, we also study the influence of higher-energy bands and find that they contribute considerable renormalization effects not captured by a low-energy two-band description. We argue that this enhancement of Drude weight and plasmon frequency occurs generally in materials characterized by electronic chirality.

Efficient enhancement of magnetic anisotropy by optimizing the ligand-field in a typically tetranuclear dysprosium cluster.

PubMed

Liu, Jiang; Chen, Yan-Cong; Jiang, Zhong-Xia; Liu, Jun-Liang; Jia, Jian-Hua; Wang, Long-Fei; Li, Quan-Wen; Tong, Ming-Liang

2015-05-07

The perturbation to the ligand field around the lanthanide ion may significantly contribute to the magnetic dynamics of single molecule magnets. This can be demonstrated by two typical Dy4 cluster-based single molecular magnets (SMMs), [Dy4X2(μ3-OH)2(μ-OH)2(2,2-bpt)4(H2O)4]X2·2H2O·4EtOH (X = Cl and Br for and , respectively), which were constructed by using 3,5-bis(pyridin-2-yl)-1,2,4-triazole (2,2-bptH) as the polynuclear-chelating ligand. Alternating-current (ac) magnetic susceptibility measurements show that the energy barriers in complexes and were immensely enhanced by comparing with our previous work due to the optimization of the ligand field around Dy(III) ions. Remarkably, their high thermal active barriers at 190 K () and 197 K () under a zero applied external dc magnetic field are also among the highest within the reported tetranuclear lanthanide-based SMMs.

Moderately nonlinear diffuse-charge dynamics under an ac voltage.

PubMed

Stout, Robert F; Khair, Aditya S

2015-09-01

The response of a symmetric binary electrolyte between two parallel, blocking electrodes to a moderate amplitude ac voltage is quantified. The diffuse charge dynamics are modeled via the Poisson-Nernst-Planck equations for a dilute solution of point-like ions. The solution to these equations is expressed as a Fourier series with a voltage perturbation expansion for arbitrary Debye layer thickness and ac frequency. Here, the perturbation expansion in voltage proceeds in powers of V_{o}/(k_{B}T/e), where V_{o} is the amplitude of the driving voltage and k_{B}T/e is the thermal voltage with k_{B} as Boltzmann's constant, T as the temperature, and e as the fundamental charge. We show that the response of the electrolyte remains essentially linear in voltage amplitude at frequencies greater than the RC frequency of Debye layer charging, D/λ_{D}L, where D is the ion diffusivity, λ_{D} is the Debye layer thickness, and L is half the cell width. In contrast, nonlinear response is predicted at frequencies below the RC frequency. We find that the ion densities exhibit symmetric deviations from the (uniform) equilibrium density at even orders of the voltage amplitude. This leads to the voltage dependence of the current in the external circuit arising from the odd orders of voltage. For instance, the first nonlinear contribution to the current is O(V_{o}^{3}) which contains the expected third harmonic but also a component oscillating at the applied frequency. We use this to compute a generalized impedance for moderate voltages, the first nonlinear contribution to which is quadratic in V_{o}. This contribution predicts a decrease in the imaginary part of the impedance at low frequency, which is due to the increase in Debye layer capacitance with increasing V_{o}. In contrast, the real part of the impedance increases at low frequency, due to adsorption of neutral salt from the bulk to the Debye layer.

The Effects of Theta and Gamma tACS on Working Memory and Electrophysiology

PubMed Central

Pahor, Anja; Jaušovec, Norbert

2018-01-01

A single blind sham-controlled study was conducted to explore the effects of theta and gamma transcranial alternating current stimulation (tACS) on offline performance on working memory tasks. In order to systematically investigate how specific parameters of tACS affect working memory, we manipulated the frequency of stimulation (theta frequency vs. gamma frequency), the type of task (n-back vs. change detection task) and the content of the tasks (verbal vs. figural stimuli). A repeated measures design was used that consisted of three sessions: theta tACS, gamma tACS and sham tACS. In total, four experiments were conducted which differed only with respect to placement of tACS electrodes (bilateral frontal, bilateral parietal, left fronto-parietal and right-fronto parietal). Healthy female students (N = 72) were randomly assigned to one of these groups, hence we were able to assess the efficacy of theta and gamma tACS applied over different brain areas, contrasted against sham stimulation. The pre-post/sham resting electroencephalogram (EEG) analysis showed that theta tACS significantly affected theta amplitude, whereas gamma tACS had no significant effect on EEG amplitude in any of the frequency bands of interest. Gamma tACS did not significantly affect working memory performance compared to sham, and theta tACS led to inconsistent changes in performance on the n-back tasks. Active theta tACS significantly affected P3 amplitude and latency during performance on the n-back tasks in the bilateral parietal and right-fronto parietal protocols. PMID:29375347

Dielectric Breakdown Characteristics of Oil-pressboard Insulation System against AC/DC Superposed Voltage

NASA Astrophysics Data System (ADS)

Ebisawa, Yoshihito; Yamada, Shin; Mori, Shigekazu; Ikeda, Masami

This paper describes breakdown characteristics of an oil-pressboard insulation system to a superposition voltage of AC and DC voltages. Although AC electric field is decided by the ratio of the relative permittivity of a pressboard and insulating oil, DC electric field is decided by ratio α of volume resistivities. From the measurement in this study, 13—78 and 1.8—5.7 are obtained as the volume resistivity ratios α at temperature of 30°C and 80°C, respectively. The breakdown voltages against AC, DC, and those superposition voltages are surveyed to insulation models. In normal temperature, the breakdown voltage to the superposition voltage of AC and DC is determined by AC electric field applied to the oil duct. Since the α becomes as low as 2-3 at temperature of 80°C, AC and DC voltages almost equally contribute to the electric field of the oil duct as a result. That is, it became clear that superposed DC voltage boosts the electric field across oil ducts at operating high temperature.

Direct Evaluation of MR-Derived Attenuation Correction Maps for PET/MR of the Mouse Myocardium

NASA Astrophysics Data System (ADS)

Evans, Eleanor; Buonincontri, Guido; Hawkes, Rob C.; Ansorge, Richard E.; Carpenter, T. Adrian; Sawiak, Stephen J.

2016-02-01

Attenuation correction (AC) must be applied to provide accurate measurements of PET tracer activity concentrations. Due to the limited space available in PET/MR scanners, MR-derived AC (MRAC) is used as a substitute for transmission source scanning. In preclinical PET/MR, there has been limited exploration of MRAC, as the magnitude of AC in murine imaging is much smaller than that required in clinical scans. We investigated if a simple 2 class (air and tissue) segmentation-based MRAC approach could provide adequate AC for mouse PET imaging. To construct the default MRAC μ maps, MR images were thresholded and segmented using ASIPRO software (Siemens Molecular Imaging), which defined the mouse body region as tissue with a uniform linear attenuation coefficient ( μ) of 0.095 cm - 1, and the background and lungs as air, with a μ value of 0 cm - 1. To correct for the misassignment of the lungs as air, two further MRAC μ maps were tested: 1) MRAC (tissue) approach, which changed the lung region designation from air to tissue ( μ = 0.095 cm - 1) and 2) MRAC (lung) approach, which treated the lungs as an additional tissue class, with a μ value of 0.032 cm - 1. All μ maps were then forward projected to create attenuation sinograms for image reconstruction. Standard uptake value (SUV) maps of the myocardium were derived for 10 mice with and without AC applied using gold standard transmission scans (TXAC), the 3 MRAC methods and PET emission scans (EmAC). All AC methods produced significantly different myocardial SUVs to those produced without AC when compared across the mouse group ( ). Similar ( ) SUV were derived with all AC methods, with the best agreement to TXAC achieved using the MRAC (tissue) method, giving a mean difference of 0.9±2.4% in myocardial SUV when compared across all mice. SUV differences of up to 40%, however, were seen in areas adjacent to the RF coil in images produced using all AC methods, except for TXAC. A 2 class MRAC approach can therefore provide acceptable AC for myocardial imaging in mice, although additional CT templates of coils and animals beds would be recommended to further improve image quantification.

Pressure-Directed Assembly: Nanostructures Made Easy

NASA Astrophysics Data System (ADS)

Fan, Hongyou

Precise control of structural parameters through nanoscale engineering to improve optical and electronic properties of functional nanomaterials continuously remains an outstanding challenge. Previous work has been conducted largely at ambient pressure and relies on specific chemical or physical interactions such as van der Waals interactions, dipole-dipole interactions, chemical reactions, ligand-receptor interactions, etc. In this presentation, I will introduce a new pressure-directed assembly method that uses mechanical compressive force applied to nanoparticle arrays to induce structural phase transition and to consolidate new nanomaterials with precisely controlled structures and tunable properties. By manipulating nanoparticle coupling through external pressure, instead of through chemistry, a reversible change in their assemblies and properties can be achieved and demonstrated. In addition, over a certain threshold, the external pressure will force these nanoparticles into contact, thereby allowing the formation and consolidation of one- to three-dimensional nanostructures. Through pressure induced nanoparticle assembly, materials engineering and synthesis become remarkably flexible without relying on traditional crystallization process where atoms/ions are locked in a specific crystal structure. Therefore, morphology or architecture can be readily tuned to produce desirable properties for practical applications. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Measuring and Modeling Organochlorine Pesticide Response to Activated Carbon Amendment in Tidal Sediment Mesocosms.

PubMed

Thompson, Jay M; Hsieh, Ching-Hong; Hoelen, Thomas P; Weston, Donald P; Luthy, Richard G

2016-05-03

Activated carbon (AC) sediment amendment for hydrophobic organic contaminants (HOCs) is attracting increasing regulatory and industrial interest. However, mechanistic and well-vetted models are needed. Here, we conduct an 18 month field mesocosm trial at a site containing dichlorodiphenyltrichloroethane (DDT) and chlordane. Different AC applications were applied and, for the first time, a recently published mass transfer model was field tested under varying experimental conditions. AC treatment was effective in reducing DDT and chlordane concentration in polyethylene (PE) samplers, and contaminant extractability by Arenicola brasiliensis digestive fluids. A substantial AC particle size effect was observed. For example, chlordane concentration in PE was reduced by 93% 6 months post-treatment in the powdered AC (PAC) mesocosm, compared with 71% in the granular AC (GAC) mesocosm. Extractability of sediment-associated DDT and chlordane by A. brasiliensis digestive fluids was reduced by at least a factor of 10 in all AC treatments. The model reproduced the relative effects of varying experimental conditions (particle size, dose, mixing time) on concentrations in polyethylene passive samplers well, in most cases within 25% of experimental observations. Although uncertainties such as the effect of long-term AC fouling by organic matter remain, the study findings support the use of the model to assess long-term implications of AC amendment.

Micro-hole array fluorescent sensor based on AC-Dielectrophoresis (DEP) for simultaneous analysis of nano-molecules

NASA Astrophysics Data System (ADS)

Kim, Hye Jin; Kang, Dong-Hoon; Lee, Eunji; Hwang, Kyo Seon; Shin, Hyun-Joon; Kim, Jinsik

2018-02-01

We propose a simple fluorescent bio-chip based on two types of alternative current-dielectrophoretic (AC-DEP) force, attractive (positive DEP) and repulsive (negative DEP) force, for simultaneous nano-molecules analysis. Various radius of micro-holes on the bio-chip are designed to apply the different AC-DEP forces, and the nano-molecules are concentrated inside the micro-hole arrays according to the intensity of the DEP force. The bio-chip was fabricated by Micro Electro Mechanical system (MEMS) technique, and was composed of two layers; a SiO2 layer and Ta/Pt layer were accomplished for an insulation layer and a top electrode with micro-hole arrays to apply electric fields for DEP force, respectively. Each SiO2 and Ta/Pt layers were deposited by thermal oxidation and sputtering, and micro-hole arrays were fabricated with Inductively Coupled Plasma (ICP) etching process. For generation of each positive and negative DEP at micro-holes, we applied two types of sine-wave AC voltage with different frequency range alternately. The intensity of the DEP force was controlled by the radius of the micro-hole and size of nano-molecule, and calculated with COMSOL multi-physics. Three types of nano-molecules labelled with different fluorescent dye were used and the intensity of nano-molecules was examined by the fluorescent optical analysis after applying the DEP force. By analyzing the fluorescent intensities of the nano-molecules, we verify the various nano-molecules in analyte are located successfully inside corresponding micro-holes with different radius according to their size.

Evaluation, development, and characterization of superconducting materials for space application

NASA Technical Reports Server (NTRS)

Thorpe, A. N.

1989-01-01

Results are reported of low magnetic field studies of dc magnetic susceptibility and ac magnetic susceptibility of bulk samples and powders. These data are analyzed and compared with the microstructures and compositions of the samples as determined by scanning electron microscopic micrographs, X-ray and chemical analysis. Particular emphasis is given to the interpretation of the ac magnetic susceptibility data which were obtained as function of the magnitude and frequency of the ac measuring field, and low values of an applied dc magnetic field. Two general conclusions are given and briefly discussed.

Spin resonance and spin fluctuations in a quantum wire

NASA Astrophysics Data System (ADS)

Pokrovsky, V. L.

2017-02-01

This is a review of theoretical works on spin resonance in a quantum wire associated with the spin-orbit interaction. We demonstrate that the spin-orbit induced internal "magnetic field" leads to a narrow spin-flip resonance at low temperatures in the absence of an applied magnetic field. An applied dc magnetic field perpendicular to and small compared with the spin-orbit field enhances the resonance absorption by several orders of magnitude. The component of applied field parallel to the spin-orbit field separates the resonance frequencies of right and left movers and enables a linearly polarized ac electric field to produce a dynamic magnetization as well as electric and spin currents. We start with a simple model of noninteracting electrons and then consider the interaction that is not weak in 1d electron system. We show that electron spin resonance in the spin-orbit field persists in the Luttinger liquid. The interaction produces an additional singularity (cusp) in the spin-flip channel associated with the plasma oscillation. As it was shown earlier by Starykh and his coworkers, the interacting 1d electron system in the external field with sufficiently large parallel component becomes unstable with respect to the appearance of a spin-density wave. This instability suppresses the spin resonance. The observation of the electron spin resonance in a thin wires requires low temperature and high intensity of electromagnetic field in the terahertz diapason. The experiment satisfying these two requirements is possible but rather difficult. An alternative approach that does not require strong ac field is to study two-time correlations of the total spin of the wire with an optical method developed by Crooker and coworkers. We developed theory of such correlations. We prove that the correlation of the total spin component parallel to the internal magnetic field is dominant in systems with the developed spin-density waves but it vanishes in Luttinger liquid. Thus, the measurement of spin correlations is a diagnostic tool to distinguish between the two states of electronic liquid in the quantum wire.

Dissection of the Mechanical Impedance Components of the Outer Hair Cell Using a Chloride-Channel Blocker

NASA Astrophysics Data System (ADS)

Harasztosi, Csaba; Gummer, Anthony W.

2011-11-01

The voltage-dependent chloride-channel blocker anthracene-9-carboxylic acid (9AC) has been found to reduce the imaginary but not the real part of the mechanical impedance of the organ of Corti, suggesting that the effective stiffness of outer hair cells (OHCs) is reduced by 9AC. To examine whether 9AC interacts directly with the motor protein prestin to reduce the membrane component of the impedance, the patch-clamp technique in whole-cell configuration was used to measure the nonlinear capacitance (NLC) of isolated OHCs and, as control, prestin-transfected human embryonic kidney 293 (HEK293) cells. Extracellular application of 9AC significantly reduced the NLC of both OHCs and HEK293 cells. Intracellular 9AC did not influence the blocking effect of the extracellular applied drug. These results suggest that 9AC interacts directly with prestin, reducing the effective stiffness of the motor, and that the interaction is extracellular.

Reduction of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes with electrolyzed oxidizing water on inoculated hass avocados (Persea americana var. Hass).

PubMed

Rodríguez-Garcia, O; González-Romero, V M; Fernández-Escartín, E

2011-09-01

This study was intended to evaluate the bactericidal effect of electrolyzed oxidizing water (EOW) and chlorinated water on populations of Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes inoculated on avocados (Persea americana var. Hass). In the first experiment, inoculated avocados were treated with a water wash applied by spraying tap water containing 1 mg/liter free chlorine for 15 s (WW); WW treatment and then spraying sodium hypochlorite in water containing 75 mg/liter free chlorine for 15 s (Cl75); WW treatment and then spraying alkaline EOW for 30 s (AkEW) and then spraying acid EOW (AcEW) for 15 s; and spraying AkEW and then AcEW. In another experiment, the inoculated avocados were treated by spraying AkEW and then AcEW for 15, 30, 60, or 90 s. All three pathogen populations were lowered between 3.6 and 3.8 log cycles after WW treatment. The application of Cl75 did not produce any further reduction in counts, whereas AkEW and then AcEW treatment resulted in significantly lower bacterial counts for L. monocytogenes and E. coli O157:H7 but not for Salmonella. Treatments with AkEW and then AcEW produced a significant decrease in L. monocytogenes, Salmonella, and E. coli O157:H7 populations, with estimated log reductions of 3.9 to 5.2, 5.1 to 5.9, and 4.2 to 4.9 log CFU/cm², respectively. Spraying AcEW for more than 15 s did not produce any further decrease in counts of Salmonella or E. coli O157:H7, whereas L. monocytogenes counts were significantly lower after spraying AcEW for 60 s. Applying AkEW and then AcEW for 15 or 30 s seems to be an effective alternative to reduce bacterial pathogens on avocado surfaces.

ac aging and space-charge characteristics in low-density polyethylene polymeric insulation

NASA Astrophysics Data System (ADS)

Chen, G.; Fu, M.; Liu, X. Z.; Zhong, L. S.

2005-04-01

In the present work efforts have been made to investigate the influence of ac aging on space-charge dynamics in low-density polyethylene (LDPE). LDPE films with 200 μm were aged under various electric stress levels at 50 Hz for various times at ambient temperature. Space-charge dynamics in the samples after aging were monitored using the pulsed electroacoustic technique. It has been revealed that the space charge under ac aging conditions is related to the level of the applied field, duration of the voltage application, as well as the electrode materials. By comparing with the results of unaged sample the results from aged sample provide a direct evidence of changing trapping characteristics after ac aging. Negative space charge is present in the bulk of the material and the total amount of charge increases with the aging time. The amount of charge increases with the applied field. Charge decay test indicates that the charges are captured in deep traps. These deep traps are believed to form during the aging and related to change caused by injected charge. By using different electrode materials such as gold, brass alloy, and polyethylene loaded with carbon black, it was found that the electrode has an important role in the formation of charge, hence subsequent changes caused by charge. The charge dynamics of the aged samples under dc bias differ from the sample without ac aging, indicating changes brought in by ac aging. Chemical analysis by Fourier transform infrared spectroscope and Raman microscope reveals no detectable chemical changes taken place in the bulk of the material after ac aging. Finally, the consequence of the accumulation of space charge under ac conditions on the lifetime of the material has been discussed. The presence of deeply trapped space charge leads to an electric stress enhancement which may shorten the lifetime of the insulation system.

Effect of Microwave Non thermal Plasma Irradiation on the Adsorptive Properties of Active Carbon Preliminarily Impregnated with Poly(vinyl alcohol)

NASA Astrophysics Data System (ADS)

Ueshima, Masato; Toda, Eriko; Nakajima, Yuki; Sugiyama, Kazuo

2010-08-01

Microwave non thermal plasma irradiation was conducted on active carbon (AC) preliminarily impregnated with poly(vinyl alcohol) (PVA) in order to modify the adsorption properties of active carbon, particularly to increase hydrophobicity. The plasma was produced by applying microwave power on the PVA-impregnated active carbon (PVA/AC) placed in a low vacuum chamber (<10 Torr). The surface of the plasma-treated PVA/AC was imaged using scanning electron microscopy and atomic force microscopy (SEM and AFM, respectively), and analyzed using X-ray photoelectron spectroscopy (XPS). Hydrophobicity of the plasma-treated PVA/AC was compared to that of untreated PVA/AC and AC by a sinking test in water/methanol mixed solutions. The hydrophobicity drastically increased for PVA/AC treatment with 1-min plasma irradiation. The AFM results indicated that the surface roughness of the PVA/AC was dependent upon the hydrophobicity, rather than reduction of free energy due to reduction of polarized functional groups. NaOH and HCl adsorption onto the plasma-treated PVA/AC was also measured. Adsorption capacity of plasma-treated PVA/AC increased for NaOH, whereas it decreased for HCl. The plasma treatment not only increased the hydrophobicity of PVA/AC, but also changed its acid-base adsorption properties. We have developed a new material based on active carbon, which is light, hydrophobic and electrically conductive by using a combination of PVA sintering and plasma irradiation.

Hybrid immersed interface-immersed boundary methods for AC dielectrophoresis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hossan, Mohammad Robiul; Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034-5209; Dillon, Robert

2014-08-01

Dielectrophoresis, a nonlinear electrokinetic transport mechanism, has become popular in many engineering applications including manipulation, characterization and actuation of biomaterials, particles and biological cells. In this paper, we present a hybrid immersed interface–immersed boundary method to study AC dielectrophoresis where an algorithm is developed to solve the complex Poisson equation using a real variable formulation. An immersed interface method is employed to obtain the AC electric field in a fluid media with suspended particles and an immersed boundary method is used for the fluid equations and particle transport. The convergence of the proposed algorithm as well as validation of themore » hybrid scheme with experimental results is presented. In this paper, the Maxwell stress tensor is used to calculate the dielectrophoretic force acting on particles by considering the physical effect of particles in the computational domain. Thus, this study eliminates the approximations used in point dipole methods for calculating dielectrophoretic force. A comparative study between Maxwell stress tensor and point dipole methods for computing dielectrophoretic forces are presented. The hybrid method is used to investigate the physics of dielectrophoresis in microfluidic devices using an AC electric field. The numerical results show that with proper design and appropriate selection of applied potential and frequency, global electric field minima can be obtained to facilitate multiple particle trapping by exploiting the mechanism of negative dielectrophoresis. Our numerical results also show that electrically neutral particles form a chain parallel to the applied electric field irrespective of their initial orientation when an AC electric field is applied. This proposed hybrid numerical scheme will help to better understand dielectrophoresis and to design and optimize microfluidic devices.« less

Electricity generation from real industrial wastewater using a single-chamber air cathode microbial fuel cell with an activated carbon anode.

PubMed

Mohamed, Hend Omar; Obaid, M; Sayed, Enas Taha; Liu, Yang; Lee, Jinpyo; Park, Mira; Barakat, Nasser A M; Kim, Hak Yong

2017-08-01

This study introduces activated carbon (AC) as an effective anode for microbial fuel cells (MFCs) using real industrial wastewater without treatment or addition of external microorganism mediators. Inexpensive activated carbon is introduced as a proper electrode alternative to carbon cloth and carbon paper materials, which are considered too expensive for the large-scale application of MFCs. AC has a porous interconnected structure with a high bio-available surface area. The large surface area, in addition to the high macro porosity, facilitates the high performance by reducing electron transfer resistance. Extensive characterization, including surface morphology, material chemistry, surface area, mechanical strength and biofilm adhesion, was conducted to confirm the effectiveness of the AC material as an anode in MFCs. The electrochemical performance of AC was also compared to other anodes, i.e., Teflon-treated carbon cloth (CCT), Teflon-treated carbon paper (CPT), untreated carbon cloth (CC) and untreated carbon paper (CP). Initial tests of a single air-cathode MFC display a current density of 1792 mAm -2 , which is approximately four times greater than the maximum value of the other anode materials. COD analyses and Coulombic efficiency (CE) measurements for AC-MFC show the greatest removal of organic compounds and the highest CE efficiency (60 and 71%, respectively). Overall, this study shows a new economical technique for power generation from real industrial wastewater with no treatment and using inexpensive electrode materials.

Electrokinetically driven microfluidic mixing with patchwise surface heterogeneity and AC applied electric field

NASA Astrophysics Data System (ADS)

Luo, Win-Jet; Yue, Cheng-Feng

2004-12-01

This paper investigates two-dimensional, time-dependent electroosmotic flows driven by an AC electric field via patchwise surface heterogeneities distributed along the microchannel walls. The time-dependent flow fields through the microchannel are simulated for various patchwise heterogeneous surface patterns using the backwards-Euler time stepping numerical method. Different heterogeneous surface patterns are found to create significantly different electrokinetic transport phenomena. It is shown that the presence of oppositely charged surface heterogeneities on the microchannel walls results in the formation of localized flow circulations within the bulk flow. These circulation regions grow and decay periodically in accordance with the applied periodic AC electric field intensity. The circulations provide an effective means of enhancing species mixing in the microchannel. A suitable design of the patchwise heterogeneous surface pattern permits the mixing channel length and the retention time required to attain a homogeneous solution to be reduced significantly.

Applications of Collisional Radiative Modeling of Helium and Deuterium for Image Tomography Diagnostic of Te, Ne, and ND in the DIII-D Tokamak

NASA Astrophysics Data System (ADS)

Munoz Burgos, J. M.; Brooks, N. H.; Fenstermacher, M. E.; Meyer, W. H.; Unterberg, E. A.; Schmitz, O.; Loch, S. D.; Balance, C. P.

2011-10-01

We apply new atomic modeling techniques to helium and deuterium for diagnostics in the divertor and scrape-off layer regions. Analysis of tomographically inverted images is useful for validating detachment prediction models and power balances in the divertor. We apply tomographic image inversion from fast tangential cameras of helium and Dα emission at the divertor in order to obtain 2D profiles of Te, Ne, and ND (neutral ion density profiles). The accuracy of the atomic models for He I will be cross-checked against Thomson scattering measurements of Te and Ne. This work summarizes several current developments and applications of atomic modeling into diagnostic at the DIII-D tokamak. Supported in part by the US DOE under DE-AC05-06OR23100, DE-FC02-04ER54698, DE-AC52-07NA27344, and DE-AC05-00OR22725.

Gene transduction in mammalian cells using Bombyx mori nucleopolyhedrovirus assisted by glycoprotein 64 of Autographa californica multiple nucleopolyhedrovirus.

PubMed

Kato, Tatsuya; Sugioka, Saki; Itagaki, Kohei; Park, Enoch Y

2016-08-26

Autographa californica multiple nucleopolyhedrovirus (AcMNPV), an alphabaculovirus, has been widely utilized for protein expression in not only insect cells but also mammalian cells. AcMNPV is closely related to Bombyx mori nucleopolyhedrovirus (BmNPV), and nucleotide sequences of AcMNPV genes have high similarity with those of BmNPV. However, the transduction of BmNPV into mammalian cells has not been reported. In this study, we constructed a recombinant BmNPV (BmNPVΔbgp/AcGP64/EGFP) whose surface 64 kDa glycoprotein (BmGP64) was substituted with that from AcMNPV (AcGP64). BmNPVΔbgp/AcGP64/EGFP also carried an EGFP gene under the control of the CMV promoter. BmNPVΔbgp/AcGP64/EGFP successfully transduced HEK293T cells. In comparison, a control construct (BmNPVΔbgp/BmGP64/EGFP) which possessed BmGP64 instead of AcGP64 did not express EGFP in HEK293T cells. The transduction efficiency of BmNPVΔbgp/AcGP64/EGFP was lower than that of an AcMNPV based-BacMam GFP transduction control. This result indicates that AcGP64 facilitates BmNPV transduction into HEK293T cells. BmNPV can be prepared easily on a large scale because BmNPV can infect silkworm larvae without any special equipment, even though specific diet is needed for silkworm rearing. BmNPV gene transduction into mammalian cells can potentially be applied easily for gene delivery into mammalian cells.

Characterizing fiber-reinforced composite structures using AC-impedance spectroscopy (AC-IS)

NASA Astrophysics Data System (ADS)

Woo, Leta Y.

Property enhancement in composites depends largely on the reinforcement. For fiber-reinforced composites, the distribution of fibers is crucial in determining the electrical and mechanical performance. Image analysis methods for characterization can be time-consuming and/or destructive. This work explores the capability of AC-impedance spectroscopy (AC-IS), an electrical measurement technique, to serve as a rapid, non-destructive tool for characterizing composite microstructure. The composite requirements include a filler that is electrically conducting or semi-conducting with higher conductivity than the matrix, and a high-impedance interface or coating between the filler and the matrix. To establish an AC-IS characterization method, cement-matrix composites with steel reinforcement were employed as both a technologically important and a model system to investigate how fibers affect the electrical response. Beginning with spherical particulates and then fibers, composites were examined using composite theory and an "intrinsic conductivity" approach. The intrinsic conductivity approach applies to composites with low volume fractions of fibers (i.e., in the dilute regime) and relates how the composite conductivity varies relative to the matrix as a function of volume fraction. A universal equivalent circuit model was created to understand the AC-IS response of composites based on the geometry and volume fraction of the filler. Deviation from predicted behavior was assessed using a developed f-function, which quantifies how fibers contribute to the overall electrical response of the composite. Using the f-function, an AC-IS method for investigating fiber dispersion was established to characterize alignment, settling/segregation, and aggregation. Alignment was investigated using measurements made in three directions. A point-probe technique characterized settling and/or large-scale inhomogeneous mixing in samples. Aggregation was quantified using a "dispersion factor" that compared theoretical with measured values and served as an upper limit for how well the fibers were dispersed. The AC-IS method was then extended to two different cement-matrix composite systems, low resistivity fresh-paste cement composites (confirmed by time domain reflectometry) and high resistivity cement composites, both of which required additional analysis to apply the AC-IS characterization method.

Evaluating the Number of Stages in Development of Squamous Cell and Adenocarcinomas across Cancer Sites Using Human Population-Based Cancer Modeling

PubMed Central

Kravchenko, Julia; Akushevich, Igor; Abernethy, Amy P.; Lyerly, H. Kim

2012-01-01

Background Adenocarcinomas (ACs) and squamous cell carcinomas (SCCs) differ by clinical and molecular characteristics. We evaluated the characteristics of carcinogenesis by modeling the age patterns of incidence rates of ACs and SCCs of various organs to test whether these characteristics differed between cancer subtypes. Methodology/Principal Findings Histotype-specific incidence rates of 14 ACs and 12 SCCs from the SEER Registry (1973–2003) were analyzed by fitting several biologically motivated models to observed age patterns. A frailty model with the Weibull baseline was applied to each age pattern to provide the best fit for the majority of cancers. For each cancer, model parameters describing the underlying mechanisms of carcinogenesis including the number of stages occurring during an individual’s life and leading to cancer (m-stages) were estimated. For sensitivity analysis, the age-period-cohort model was incorporated into the carcinogenesis model to test the stability of the estimates. For the majority of studied cancers, the numbers of m-stages were similar within each group (i.e., AC and SCC). When cancers of the same organs were compared (i.e., lung, esophagus, and cervix uteri), the number of m-stages were more strongly associated with the AC/SCC subtype than with the organ: 9.79±0.09, 9.93±0.19 and 8.80±0.10 for lung, esophagus, and cervical ACs, compared to 11.41±0.10, 12.86±0.34 and 12.01±0.51 for SCCs of the respective organs (p<0.05 between subtypes). Most SCCs had more than ten m-stages while ACs had fewer than ten m-stages. The sensitivity analyses of the model parameters demonstrated the stability of the obtained estimates. Conclusions/Significance A model containing parameters capable of representing the number of stages of cancer development occurring during individual’s life was applied to the large population data on incidence of ACs and SCCs. The model revealed that the number of m-stages differed by cancer subtype being more strongly associated with ACs/SCCs histotype than with organ/site. PMID:22629394

Dielectrophoretic particle-particle interaction under AC electrohydrodynamic flow conditions.

PubMed

Lee, Doh-Hyoung; Yu, Chengjie; Papazoglou, Elisabeth; Farouk, Bakhtier; Noh, Hongseok M

2011-09-01

We used the Maxwell stress tensor method to understand dielectrophoretic particle-particle interactions and applied the results to the interpretation of particle behaviors under alternating current (AC) electrohydrodynamic conditions such as AC electroosmosis (ACEO) and electrothermal flow (ETF). Distinct particle behaviors were observed under ACEO and ETF. Diverse particle-particle interactions observed in experiments such as particle clustering, particles keeping a certain distance from each other, chain and disc formation and their rotation, are explained based on the numerical simulation data. The improved understanding of particle behaviors in AC electrohydrodynamic flows presented here will enable researchers to design better particle manipulation strategies for lab-on-a-chip applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnus-induced ratchet effects for skyrmions interacting with asymmetric substrates

NASA Astrophysics Data System (ADS)

Reichhardt, C.; Ray, D.; Olson Reichhardt, C. J.

2015-07-01

We show using numerical simulations that pronounced ratchet effects can occur for ac driven skyrmions moving over asymmetric quasi-one-dimensional substrates. We find a new type of ratchet effect called a Magnus-induced transverse ratchet that arises when the ac driving force is applied perpendicular rather than parallel to the asymmetry direction of the substrate. This transverse ratchet effect only occurs when the Magnus term is finite, and the threshold ac amplitude needed to induce it decreases as the Magnus term becomes more prominent. Ratcheting skyrmions follow ordered orbits in which the net displacement parallel to the substrate asymmetry direction is quantized. Skyrmion ratchets represent a new ac current-based method for controlling skyrmion positions and motion for spintronic applications.

Stress-related phenomena and detoxification mechanisms induced by common pharmaceuticals in alfalfa (Medicago sativa L.) plants.

PubMed

Christou, Anastasis; Antoniou, Chrystalla; Christodoulou, Charalampia; Hapeshi, Evroula; Stavrou, Ioannis; Michael, Costas; Fatta-Kassinos, Despo; Fotopoulos, Vasileios

2016-07-01

Pharmaceutically active compounds (PhACs) have been recently shown to exert phytotoxic effects. The present study explores the uptake, systemic translocation, and abiotic stress responses and detoxification mechanisms induced by the exposure of alfalfa plants grown in sand under greenhouse conditions to four common, individually applied PhACs (10μgL(-1)) (diclofenac, sulfamethoxazole, trimethoprim, 17a-ethinylestradiol) and their mixture. Stress physiology markers (lipid peroxidation, proline, H2O2 and NO content, antioxidant activity assays) and gene expression levels of key plant detoxification components (including glutathione S-transferases, GST7, GST17; superoxide dismutases, CuZnSOD, FeSOD; proton pump, H(+)-ATP, and cytochrome c oxidase, CytcOx), were evaluated. PhACs were detected in significantly higher concentrations in roots compared with leaves. Stress related effects, manifested via membrane lipid peroxidation and oxidative burst, were local (roots) rather than systemic (leaves), and exacerbated when the tested PhACs were applied in mixture. Systemic accumulation of H2O2 in leaves suggests its involvement in signal transduction and detoxification responses. Increased antioxidant enzymatic activities, as well as upregulated transcript levels of GST7, GST17, H(+)-ATPase and CytcOx, propose their role in the detoxification of the selected PhACs in plants. The current findings provide novel biochemical and molecular evidence highlighting the studied PhACs as an emerging abiotic stress factor, and point the need for further research on wastewater flows under natural agricultural environments. Copyright © 2016 Elsevier B.V. All rights reserved.

Weak extremely-low-frequency magnetic field-induced regeneration anomalies in the planarian, Dugesia tigrina

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenrow, K.A.; Smith, C.H.; Liboff, A.R.

1996-12-31

The authors recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC magnetic fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. The authors report here, in a parallel series of investigations on the same model system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz magnetic fields, with peak intensities ranging between 1.0 and 80.0 {micro}T. These anomalies often culminate in the complete disaggregation of the organism. Similarmore » to regeneration rate effects, the incidence of regeneration anomalies is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the regeneration rate effects, the AC magnetic field alone, in the absence of any measurable DC field, is capable of producing these anomalies. Moreover, the incidence of regeneration anomalies follows a clear dose-response relationship as a function of AC magnetic field intensity, with the threshold for induced electric field intensity estimated at 5 {micro} V/m. The addition of either 51.1 or 78.4 {micro}T DC magnetic fields, applied in parallel combination with the AC field, enhances the appearance of anomalies relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas the previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling.« less

Method for making glass nonfogging

DOEpatents

Lord, David E.; Carter, Gary W.; Petrini, Richard R.

1979-01-01

A method for rendering glass nonfogging (to condensation fog) by sandwiching the glass between two electrodes such that the glass functions as the dielectric of a capacitor, a large alternating current (AC) voltage is applied across the electrodes for a selected time period causing the glass to absorb a charge, and the electrodes are removed. The glass absorbs a charge from the electrodes rendering it nonfogging. The glass surface is undamaged by application of the AC voltage, and normal optical properties are unaffected. This method can be applied to optical surfaces such as lenses, auto windshields, mirrors, etc., wherever condensation fog on glass is a problem.

Aligning fast alternating current electroosmotic flow fields and characteristic frequencies with dielectrophoretic traps to achieve rapid bacteria detection.

PubMed

Gagnon, Zachary; Chang, Hsueh-Chia

2005-10-01

Tailor-designed alternating current electroosmotic (AC-EO) stagnation flows are used to convect bioparticles globally from a bulk solution to localized dielectrophoretic (DEP) traps that are aligned at the flow stagnation points. The multiscale trap, with a typical trapping time of seconds for a dilute 70 microL volume of 10(3) particles per cc sample, is several orders of magnitude faster than conventional DEP traps and earlier AC-EO traps with parallel, castellated, or finger electrodes. A novel serpentine wire capable of sustaining a high voltage, up to 2500 V(RMS), without causing excessive heat dissipation or Faradaic reaction in strong electrolytes is fabricated to produce the strong AC-EO flow with two separated stagnation lines, one aligned with the field minimum and one with the field maximum. The continuous wire design allows a large applied voltage without inducing Faradaic electrode reactions. Particles are trapped within seconds at one of the traps depending on whether they suffer negative or positive DEP. The particles can also be rapidly released from their respective traps by varying the frequency of the applied AC field below particle-distinct cross-over frequencies. Zwitterion addition to the buffer allows further geometric and frequency alignments of the AC-EO and DEP motions. The same device hence allows fast trapping, detection, sorting, and characterization on a sample with realistic conductivity, volume, and bacteria count.

The Adjuvant Effects of High-Molecule-Weight Polysaccharides Purified from Antrodia cinnamomea on Dendritic Cell Function and DNA Vaccines

PubMed Central

Lin, Chi-Chen; Pan, I-Hong; Li, Yi-Rong; Pan, Yi-Gen; Lin, Ming-Kuem; Lu, Yi-Huang; Wu, Hsin-Chieh; Chu, Ching-Liang

2015-01-01

The biological activity of the edible basidiomycete Antrodia cinnamomea (AC) has been studied extensively. Many effects, such as anti-cancer, anti-inflammatory, and antioxidant activities, have been reported from either crude extracts or compounds isolated from AC. However, research addressing the function of AC in enhancing immunity is rare. The aim of the present study is to investigate the active components and the mechanism involved in the immunostimulatory effect of AC. We found that polysaccharides (PS) in the water extract of AC played a major role in dendritic cell (DC) activation, which is a critical leukocyte in initiating immune responses. We further size purified and identified that the high-molecular weight PS fraction (greater than 100 kDa) exhibited the activating effect. The AC high-molecular weight PSs (AC hmwPSs) promoted pro-inflammatory cytokine production by DCs and the maturation of DCs. In addition, DC-induced antigen-specific T cell activation and Th1 differentiation were increased by AC hmwPSs. In studying the molecular mechanism, we confirmed the activation of the MAPK and NF-κB pathways in DCs after AC hmwPSs treatment. Furthermore, we demonstrated that TLR2 and TLR4 are required for the stimulatory activity of AC hmwPSs on DCs. In a mouse tumor model, we demonstrated that AC hmwPSs enhanced the anti-tumor efficacy of the HER-2/neu DNA vaccine by facilitating specific Th1 responses. Thus, we conclude that hmwPSs are the major components of AC that stimulate DCs via the TLR2/TLR4 and NF-κB/MAPK signaling pathways. The AC hmwPSs have potential to be applied as adjuvants. PMID:25723174

First observation of N-acetyl leucine and N-acetyl isoleucine in diabetic patient hair and quantitative analysis by UPLC-ESI-MS/MS.

PubMed

Min, Jun Zhe; Tomiyasu, Yuki; Morotomi, Takashi; Jiang, Ying-Zi; Li, Gao; Shi, Qing; Yu, Hai-Fu; Inoue, Koichi; Todoroki, Kenichiro; Toyo'oka, Toshimasa

2015-04-15

Type 2 diabetes patients (DP) have significantly higher plasma levels of valine, leucine, isoleucine and alanine than the controls. Specific amino acids may acutely and chronically regulate insulin secretion from the pancreatic β-cells. We recently identified a metabolic signature of N-acetyl leucine (Ac-Leu) that strongly predicts diabetes development in mice hair. The Ac-Leu appears to be a potential biomarker candidate related to diabetes. However, the determination of Ac-Leu in human hair has not been reported. We measured the Ac-Leu, and its structure is similar to N-acetyl isoleucine (Ac-Ile) in human hair by ultra-performance liquid chromatography (UPLC) with electrospray ionization tandem mass spectrometry (ESI-MS/MS). The developed method was applied to the determination of Ac-Leu and Ac-Ile in the hair of healthy volunteers (HV) and DP. Ac-Leu, Ac-Ile and N-acetyl norleucine (Ac-Nle, IS) were extracted from human hair samples by a micropulverized extraction procedure, then separated on a C18 column by isocratic elution of acetonitrile-0.1% formic acid in water:0.1% formic acid (14:86, vol./vol.). MRM using the fragmentation transitions of m/z 174.1→86.1 in the positive ESI mode was performed to quantify the N-acetyl leucine, N-acetyl isoleucine and IS. Ac-Leu, Ac-Ile and Ac-Nle in the human hair samples were completely separated by isocratic elution of a 5.0 min duration wash program using a reversed-phase column, and sensitively detected by LC-MS/MS in the ESI(+) MRM mode. The amounts of Ac-Leu and Ac-Ile in the hairs of HV and DP were determined. When comparing the concentrations between DP and those from HV, a statistically significant correlation was observed for the Ac-Leu (p<0.001) and Ac-Ile (p<0.01). The proposed method is useful for the determination of Ac-Leu and Ac-Ile in the hairs of DP and HV. Human hair may serve as a noninvasive biosample for the diagnosis of diabetes. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

Soap-film flow induced by electric fields in asymmetric frames

NASA Astrophysics Data System (ADS)

Mollaei, S.; Nasiri, M.; Soltanmohammadi, N.; Shirsavar, R.; Ramos, A.; Amjadi, A.

2018-04-01

Net fluid flow of soap films induced by (ac or dc) electric fields in asymmetric frames is presented. Previous experiments of controllable soap film flow required the simultaneous use of an electrical current passing through the film and an external electric field or the use of nonuniform ac electric fields. Here a single voltage difference generates both the electrical current going through the film and the electric field that actuates on the charge induced on the film. The film is set into global motion due to the broken symmetry that appears by the use of asymmetric frames. If symmetric frames are used, the film flow is not steady but time dependent and irregular. Finally, we study numerically these film flows by employing the model of charge induction in ohmic liquids.

Soap-film flow induced by electric fields in asymmetric frames.

PubMed

Mollaei, S; Nasiri, M; Soltanmohammadi, N; Shirsavar, R; Ramos, A; Amjadi, A

2018-04-01

Net fluid flow of soap films induced by (ac or dc) electric fields in asymmetric frames is presented. Previous experiments of controllable soap film flow required the simultaneous use of an electrical current passing through the film and an external electric field or the use of nonuniform ac electric fields. Here a single voltage difference generates both the electrical current going through the film and the electric field that actuates on the charge induced on the film. The film is set into global motion due to the broken symmetry that appears by the use of asymmetric frames. If symmetric frames are used, the film flow is not steady but time dependent and irregular. Finally, we study numerically these film flows by employing the model of charge induction in ohmic liquids.

The First Layer of 4He, H2, and Ne Adsorbed on HiPco™ Carbon Nanotube Bundles

NASA Astrophysics Data System (ADS)

Vilches, O. E.; Ramachandran, S.; Wilson, T. A.; Dash, J. G.

2006-09-01

We summarize results from AC and DC heat capacity measurements of 4He, H2, and Ne adsorbed on HiPco™ purified, closed-end single-wall carbon nanotube bundles (SWNTB) for the first adsorbed layer. We find two regions in the coverage domain: below ≈1/3 monolayer the adsorbate occupies high binding energy sites, mostly the external grooves of the bundles, while above ≈1/3 monolayer the external graphene surface is covered. No phase transitions have been observed at any temperature for all the adsorbates, a range of T where two-dimensional phases and phase transitions are seen for the same adsorbates deposited on exfoliated graphite.

Hardwood Control by Injection With Two New Chemicals

Treesearch

J.L. Michael

1985-01-01

AC 252,925 [Arsenal®], and 3,6-dichloropicolinic acid (XRM-3972) were tested at two different strengths against seven hardwood species. Triclopyr [Garlon 3A®] was used as a standard, making a total of five herbicide treatments. All treatments were applied in June 1983. Fifteen months after treatment, only AC 252,925 gave acceptable kill over the entire range of...

Anatomical Calibration through Post-Processing of Standard Motion Tests Data.

PubMed

Kong, Weisheng; Sessa, Salvatore; Zecca, Massimiliano; Takanishi, Atsuo

2016-11-28

The inertial measurement unit is popularly used as a wearable and flexible tool for human motion tracking. Sensor-to-body alignment, or anatomical calibration (AC), is fundamental to improve accuracy and reliability. Current AC methods either require extra movements or are limited to specific joints. In this research, the authors propose a novel method to achieve AC from standard motion tests (such as walking, or sit-to-stand), and compare the results with the AC obtained from specially designed movements. The proposed method uses the limited acceleration range on medial-lateral direction, and applies principal component analysis to estimate the sagittal plane, while the vertical direction is estimated from acceleration during quiet stance. The results show a good correlation between the two sets of IMUs placed on frontal/back and lateral sides of head, trunk and lower limbs. Moreover, repeatability and convergence were verified. The AC obtained from sit-to-stand and walking achieved similar results as the movements specifically designed for upper and lower body AC, respectively, except for the feet. Therefore, the experiments without AC performed can be recovered through post-processing on the walking and sit-to-stand data. Moreover, extra movements for AC can be avoided during the experiment and instead achieved through the proposed method.

A Combined Field and Laboratory Study on Activated Carbon-Based Thin Layer Capping in a PCB-Contaminated Boreal Lake.

PubMed

Abel, Sebastian; Akkanen, Jarkko

2018-04-17

The in situ remediation of aquatic sediments with activated carbon (AC)-based thin layer capping is a promising alternative to traditional methods, such as sediment dredging. Applying a strong sorbent like AC directly to the sediment can greatly reduce the bioavailability of organic pollutants. To evaluate the method under realistic field conditions, a 300 m 2 plot in the PCB-contaminated Lake Kernaalanjärvi, Finland, was amended with an AC cap (1.6 kgAC/m 2 ). The study lake showed highly dynamic sediment movements over the monitoring period of 14 months. This led to poor retention and rapid burial of the AC cap under a layer of contaminated sediment from adjacent sites. As a result, the measured impact of the AC amendment was low: Both the benthic community structure and PCB bioaccumulation were similar on the plot and in surrounding reference sites. Corresponding follow-up laboratory studies using Lumbriculus variegatus and Chironomus riparius showed that long-term remediation success is possible, even when an AC cap is covered with contaminated sediment. To retain a measurable effectiveness (reduction in contaminant bioaccumulation), a sufficient intensity and depth of bioturbation is required. On the other hand, the magnitude of the adverse effect induced by AC correlated positively with the measured remediation success.

Intralaminar stimulation of the inferior colliculus facilitates frequency-specific activation in the auditory cortex

NASA Astrophysics Data System (ADS)

Allitt, B. J.; Benjaminsen, C.; Morgan, S. J.; Paolini, A. G.

2013-08-01

Objective. Auditory midbrain implants (AMI) provide inadequate frequency discrimination for open set speech perception. AMIs that can take advantage of the tonotopic laminar of the midbrain may be able to better deliver frequency specific perception and lead to enhanced performance. Stimulation strategies that best elicit frequency specific activity need to be identified. This research examined the characteristic frequency (CF) relationship between regions of the auditory cortex (AC), in response to stimulated regions of the inferior colliculus (IC), comparing monopolar, and intralaminar bipolar electrical stimulation. Approach. Electrical stimulation using multi-channel micro-electrode arrays in the IC was used to elicit AC responses in anaesthetized male hooded Wistar rats. The rate of activity in AC regions with CFs within 3 kHz (CF-aligned) and unaligned CFs was used to assess the frequency specificity of responses. Main results. Both monopolar and bipolar IC stimulation led to CF-aligned neural activity in the AC. Altering the distance between the stimulation and reference electrodes in the IC led to changes in both threshold and dynamic range, with bipolar stimulation with 400 µm spacing evoking the lowest AC threshold and widest dynamic range. At saturation, bipolar stimulation elicited a significantly higher mean spike count in the AC at CF-aligned areas than at CF-unaligned areas when electrode spacing was 400 µm or less. Bipolar stimulation using electrode spacing of 400 µm or less also elicited a higher rate of elicited activity in the AC in both CF-aligned and CF-unaligned regions than monopolar stimulation. When electrodes were spaced 600 µm apart no benefit over monopolar stimulation was observed. Furthermore, monopolar stimulation of the external cortex of the IC resulted in more localized frequency responses than bipolar stimulation when stimulation and reference sites were 200 µm apart. Significance. These findings have implications for the future development of AMI, as a bipolar stimulation strategy may improve the ability of implant users to discriminate between frequencies.

A Particle-in-Cell Simulation for the Traveling Wave Direct Energy Converter (TWDEC) for Fusion Propulsion

NASA Technical Reports Server (NTRS)

Chap, Andrew; Tarditi, Alfonso G.; Scott, John H.

2013-01-01

A Particle-in-cell simulation model has been developed to study the physics of the Traveling Wave Direct Energy Converter (TWDEC) applied to the conversion of charged fusion products into electricity. In this model the availability of a beam of collimated fusion products is assumed; the simulation is focused on the conversion of the beam kinetic energy into alternating current (AC) electric power. The model is electrostatic, as the electro-dynamics of the relatively slow ions can be treated in the quasistatic approximation. A two-dimensional, axisymmetric (radial-axial coordinates) geometry is considered. Ion beam particles are injected on one end and travel along the axis through ring-shaped electrodes with externally applied time-varying voltages, thus modulating the beam by forming a sinusoidal pattern in the beam density. Further downstream, the modulated beam passes through another set of ring electrodes, now electrically oating. The modulated beam induces a time alternating potential di erence between adjacent electrodes. Power can be drawn from the electrodes by connecting a resistive load. As energy is dissipated in the load, a corresponding drop in beam energy is measured. The simulation encapsulates the TWDEC process by reproducing the time-dependent transfer of energy and the particle deceleration due to the electric eld phase time variations.

The low magnetic field properties of superconducting bulk yttrium barium copper oxide - Sintered versus partially melted material

NASA Technical Reports Server (NTRS)

Hein, R. A.; Hojaji, H.; Barkatt, A.; Shafii, H.; Michael, K. A.; Thorpe, A. N.; Ware, M. F.; Alterescu, S.

1989-01-01

A comparison of the low magnetic field properties of sintered (990 C) and partially melted samples (1050 C) has been performed. Changes in the microstructure produced by recrystallization from the melt result in a significant increase in flux pinning at 77 K. Low-frequency (10-100 Hz), low-ac magnetic-field (0.01-9.0 Oe) ac susceptibility data show that gross changes in the loss component accompany the observed changes in microstructure. The effects of applied dc magnetic fields (10-220 Oe) on the ac responses of these microstructures have also been probed.

Dimensionality of superconductivity in the layered organic material EtMe3P [Pd(dmit)2] 2 under pressure

NASA Astrophysics Data System (ADS)

Yamamoto, R.; Yanagita, Y.; Namaizawa, T.; Komuro, S.; Furukawa, T.; Itou, T.; Kato, R.

2018-06-01

We measured the ac magnetic susceptibility for the layered organic superconductor EtMe3P [Pd(dmit)2] 2 under pressure with a dc magnetic field applied perpendicular to the ac field. We investigated the dc field dependence of the ac susceptibility in detail and concluded that the superconductivity in EtMe3P [Pd(dmit)2] 2 is an anisotropic three-dimensional superconductivity even at low temperatures, which contrasts with the large majority of other correlated electron layered superconductors such as high-Tc cuprate and κ -(ET) 2X systems.

Analysis of amino acids and acyl carnitine profiles in low birth weight, preterm, and small for gestational age neonates.

PubMed

Liu, Qian; Wu, Jing; Shen, Wen; Wei, Ran; Jiang, Jianhui; Liang, Jinqun; Chen, Min; Zhong, Mei; Yin, Aihua

2017-11-01

To analyze the amino acids (AA) and acyl carnitine (AC) profiles in dry blood spot (DBS) specimens of low birth weight (LBW), preterm birth (PTB), and small for gestational age (SGA), and to compare the concentration difference of AA and AC with those without above. This is a retrospectively study. Eight thousand nine hundred and seventy-nine uncomplicated pregnant newborns were enrolled into the study. DBS were collected on the third day of life, and concentrations of 11 types of AA, free carnitine and 30 types of AC were detected by using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS). Shapiro-Wilk test and Kruskal-Wallis rank test were applied in statistical analysis. Concentrations of most AA and AC in infants born in SGA were significantly higher than those in non-SGA group, while lower in LBW and PTB groups than those in non-LBW and non-PTB groups (p < 0.05). The difference of concentration of AA and AC in the subgroups suggested there may be a dysutilization of AA and AC in SGA, but an inborn insufficient of AA and AC in LBW and PTB neonates.

Study of the Dependence on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

NASA Technical Reports Server (NTRS)

Bandler, Simon

2011-01-01

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in the AC bias configuration. For x-ray photons at 6keV the AC biased pixel shows a best energy resolution of 3.7eV, which is about a factor of 2 worse than the energy resolution observed in identical DC-biased pixels. To better understand the reasons of this discrepancy, we investigated the detector performance as a function of temperature, bias working point and applied magnetic field. A strong periodic dependence of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recent weak-link behaviour observed inTES microcalorimeters.

Electroosmosis through a Cation-Exchange Membrane: Effect of an ac Perturbation on the Electroosmotic Flow.

PubMed

Barragán; Ruíz Bauzá C

2000-10-15

Electroosmosis experiments through a cation-exchange membrane have been performed using NaCl solutions in different experimental situations. The influence of an alternating (ac) sinusoidal perturbation, of known angular frequency and small amplitude, superimposed to the usual applied continuous (dc) signal on the electroosmotic flow has been studied. The experimental results show that the presence of the ac perturbation affects the electroosmotic flow value, depending on the frequency of the ac signal and on the solution stirring conditions. In the frequency range studied, two regions have been observed where the electroosmotic flow reaches a maximum value: one at low frequencies ( approximately Hz); and another at frequencies of the order of kHz. These regions could be related to membrane relaxation phenomena. Copyright 2000 Academic Press.

System for transmitting low frequency analog signals over AC power lines

DOEpatents

Baker, Steven P.; Durall, Robert L.; Haynes, Howard D.

1989-01-01

A system for transmitting low frequency analog signals over AC power lines using FM modulation. A low frequency analog signal to be transmitted is first applied to a voltage-to-frequency converter where it is converted to a signal whose frequency varies in proportion to the analog signal amplitude. This signal is then used to modulate the carrier frequency of an FM transmitter coupled to an AC power line. The modulation signal frequency range in selected to be within the response band of the FM transmitter. The FM modulated carrier signal is received by an FM receiver coupled to the AC power line, demodulated and the demodulated signal frequency is converted by a frequency-to-voltage converter back to the form of the original low frequency analog input signal.

System for transmitting low frequency analog signals over AC power lines

DOEpatents

Baker, Steven P.; Durall, Robert L.; Haynes, Howard D.

1989-09-05

A system for transmitting low frequency analog signals over AC power lines using FM modulation. A low frequency analog signal to be transmitted is first applied to a voltage-to-frequency converter where it is converted to a signal whose frequency varies in proportion to the analog signal amplitude. This signal is then used to modulate the carrier frequency of an FM transmitter coupled to an AC power line. The modulation signal frequency range in selected to be within the response band of the FM transmitter. The FM modulated carrier signal is received by an FM receiver coupled to the AC power line, demodulated and the demodulated signal frequency is converted by a frequency-to-voltage converter back to the form of the original low frequency analog input signal.

A system for tranmitting low frequency analog signals over ac power lines

DOEpatents

Baker, S.P.; Durall, R.L.; Haynes, H.D.

1987-07-30

A system for transmitting low frequency analog signals over ac power lines using FM modulation. A low frequency analog signal to be transmitted is first applied to a voltage-to-frequency converter where it is converted to a signal whose frequency varies in proportion to the analog signal amplitude. This signal is then used to modulate the carrier frequency of an FM transmitter coupled to an ac power line. The modulation signal frequency range is selected to be within the response band of the FM transmitter. The FM modulated carrier signal is received by an FM receiver coupled to the ac power line, demodulated and the demodulated signal frequency is converted by a frequency-to-voltage converter back to the form of the original low frequency analog input signal. 4 figs.

Magnus-induced ratchet effects for skyrmions interacting with asymmetric substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reichhardt, C.; Ray, D.; Reichhardt, C. J. Olson

2015-07-31

We show using numerical simulations that pronounced ratchet effects can occur for ac driven skyrmions moving over asymmetric quasi-one-dimensional substrates. We find a new type of ratchet effect called a Magnus-induced transverse ratchet that arises when the ac driving force is applied perpendicular rather than parallel to the asymmetry direction of the substrate. This transverse ratchet effect only occurs when the Magnus term is finite, and the threshold ac amplitude needed to induce it decreases as the Magnus term becomes more prominent. Ratcheting skyrmions follow ordered orbits in which the net displacement parallel to the substrate asymmetry direction is quantized.more » As a result, skyrmion ratchets represent a new ac current-based method for controlling skyrmion positions and motion for spintronic applications.« less

Topological effects in quantum mechanics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peshkin, M.; Lipkin, H.J.

We completed our analysis of experiments, some completed, some planned, and some only conceptual at present, that purport to demonstrate new kinds of non-local and topological effects in the interaction of a neutron with an external electromagnetic field. In the Aharonov-Casher effect (AC), the neutron interacts with an electric field and in the Scalar Aharonov-Bohm effect (SAB) the neutron interacts with a magnetic field. In both cases, the geometry can be arranged so that there is no force on the neutron but an interference experiment nevertheless finds a phase shift proportional to the applied field and to the neutron`s magneticmore » moment. Previously, we showed that the accepted interpretation of these phenomena as topological effects due to a non-local interaction between the neutron and the electromagnetic field is incorrect. Both AC and SAB follow from local torques on the neutron whose expectation values vanish at every instant but which have non-vanishing effect on the measurable spin-correlation variables S(t) = (1/2) [{sigma}{sub x}{sigma}{sub x}(t) + {sigma}{sub y}(0){sigma}{sub y}(t) + h.c.] and V(t) = [{sigma}{sub x}(0){sigma}{sub y}(t) - {sigma}{sub y}(0){sigma}{sub x}(t) + h.c.]. We have now completed this work by observing that a criterion often used for identifying a topological effect, energy independence of the phase shift between two arms of an interferometer, is only a necessary condition, and by describing a phase shifter which obeys the energy-independence condition but whose interaction with the neutron is neither topological nor even non-local.« less

Measurement of internal defects in aluminum using a nano-granular in-gap magnetic sensor

NASA Astrophysics Data System (ADS)

Ozawa, T.; Yabukami, S.; Totsuka, J.; Koyama, S.; Hayasaka, J.; Wako, N.; Arai, K. I.

2015-05-01

Techniques for identifying defects in metals are very important in a wide variety of manufacturing areas. The present paper reports an eddy current testing method that employs a nano-granular in-gap magnetic sensor (GIGS) to detect internal defects in aluminum boards. The GIGS consists of a tunnel magnetoresistive film with nanometer sized grains and two yokes. In the presence of an external magnetic field, the nano-granular film exhibits only a small change in resistance due to the tunnel magnetoresistive effect. However, by placing it between two yokes, the magnetic flux can be greatly concentrated, thus increasing the change in resistance. The GIGS is a magnetic-field sensor that exploits this principle to achieve enhanced sensitivity. Moreover, because it has a cross-sectional yolk area of just 80 μm × 0.5 μm, it achieves outstanding spatial resolution. In the present study, it is used in combination with an eddy-current method in order to detect internal defects in aluminum. In this method, an excitation coil is used to apply an AC magnetic field perpendicular to the aluminum surface. This induces eddy currents in the metal, which in turn give rise to an AC magnetic field, which is then measured by the GIGS. The presence of defects in the aluminum distorts the eddy current flow, causing a change in the magnitude and distribution of the magnetic field. Such changes can be detected using the GIGS. In the present study, the proposed method was used to successfully detect indentations with diameters of 5 mm on the rear surface of an aluminum plate.

Continuous evolution of B. thuringiensis toxins overcomes insect resistance

PubMed Central

Badran, Ahmed H.; Guzov, Victor M.; Huai, Qing; Kemp, Melissa M.; Vishwanath, Prashanth; Kain, Wendy; Nance, Autumn M.; Evdokimov, Artem; Moshiri, Farhad; Turner, Keith H.; Wang, Ping; Malvar, Thomas; Liu, David R.

2016-01-01

The Bacillus thuringiensis δ-endotoxins (Bt toxins) are widely used insecticidal proteins in engineered crops that provide agricultural, economic, and environmental benefits. The development of insect resistance to Bt toxins endangers their long-term effectiveness. We developed a phage-assisted continuous evolution (PACE) selection that rapidly evolves high-affinity protein-protein interactions, and applied this system to evolve variants of the Bt toxin Cry1Ac that bind a cadherin-like receptor from the insect pest Trichoplusia ni (TnCAD) that is not natively targeted by wild-type Cry1Ac. The resulting evolved Cry1Ac variants bind TnCAD with high affinity (Kd = 11–41 nM), kill TnCAD-expressing insect cells that are not susceptible to wild-type Cry1Ac, and kill Cry1Ac-resistant T. ni insects up to 335-fold more potently than wild-type Cry1Ac. Our findings establish that the evolution of Bt toxins with novel insect cell receptor affinity can overcome Bt toxin resistance in insects and confer lethality approaching that of the wild-type Bt toxin against non-resistant insects. PMID:27120167

Calculation of gas release from DC and AC arc furnaces in a foundry

NASA Astrophysics Data System (ADS)

Krutyanskii, M. M.; Nekhamin, S. M.; Rebikov, E. M.

2016-12-01

A procedure for the calculation of gas release from arc furnaces is presented. The procedure is based on the stoichiometric ratios of the oxidation of carbon in liquid iron during the oxidation heat period and the oxidation of iron from a steel charge by oxygen in the period of solid charge melting during the gas exchange of the furnace cavity with the external atmosphere.

Dynamic self-assembly and self-organized transport of magnetic micro-swimmers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kokot, Gasper; Kolmakov, German V.; Aranson, Igor S.

We demonstrate experimentally and in computer simulations that magnetic microfloaters can self-organize into various functional structures while energized by an external alternating (ac) magnetic field. The structures exhibit self-propelled motion and an ability to carry a cargo along a pre-defined path. As a result, the morphology of the self-assembled swimmers is controlled by the frequency and amplitude of the magnetic field.

Nonlinear Equations of Motion for a Panel Subject to External Loads

DTIC Science & Technology

1993-11-01

axay 4- ax) 4 , ay sin The x, y, and xy curvatures are extracted from this equation. The squared terms within the brackets are neglected because they...2B= +0 Solving for results in dOz dOt -B ± VB2 -AC dOz C and after substituting in the values of the coefficients from Equation (66)dO’ aO d = - zz±c

Dynamic self-assembly and self-organized transport of magnetic micro-swimmers

DOE PAGES

Kokot, Gasper; Kolmakov, German V.; Aranson, Igor S.; ...

2017-11-07

We demonstrate experimentally and in computer simulations that magnetic microfloaters can self-organize into various functional structures while energized by an external alternating (ac) magnetic field. The structures exhibit self-propelled motion and an ability to carry a cargo along a pre-defined path. As a result, the morphology of the self-assembled swimmers is controlled by the frequency and amplitude of the magnetic field.

Houston-Galveston Vessel Traffic Service Watchstander Analysis

DTIC Science & Technology

1978-05-01

12 ~neincludedncye Nof te cete’ frs n logs,11 reod of ntchteri Ac’tiv e for. Deartotal of iTeen husp o bevto naio tmdeaumeso ypiolpath wfithcenter...2-10 2.5 Operating Positions ...................... 2- 12 2.5,1 Watch Supervisor .................. 2- 12 2.5.2 Sector...Watchatander er.............. 2- 12 2.5.3 External Conmmunicator ............. 2-13 2.6 Equipment and Workspace ....... . . . . . . . . . . . 2 - 1 3 S2.6.1 VHF

An initial physical mechanism in the treatment of neurologic disorders with externally applied pico Tesla magnetic fields.

PubMed

Jacobson, J I; Yamanashi, W S

1995-04-01

The recent clinical studies describing the treatment of some neurological disorders with an externally applied pico Tesla (10(-12) Tesla, or 10(-8) gauss) magnetic field are considered from a physical view point. An equation relating the intrinsic (or rest) energy of a charged particle of mass m with its energy of interaction in an externally applied magnetic field B is presented. The equation represents an initial basic physical interaction as a part of a more complex biological mechanism to explain the therapeutic effects of externally applied magnetic fields in these and other neurologic disorders.

A physical mechanism in the treatment of neurologic disorders with externally applied pico Tesla magnetic fields.

PubMed

Jacobson, J I; Yamanashi, W S

1995-06-01

The clinical studies describing the treatment of some neurological disorders with an externally applied pico Tesla (10R Tesla, or 10(-8) gauss) magnetic field are considered from a physical view point. An equation relating the intrinsic or "rest" energy of a charged particle of mass with its energy of interaction in an externally applied magnetic field B is presented. The equation is proposed to represent an initial basic physical interaction as a part of a more complex biological mechanism to explain the therapeutic effects of externally applied magnetic fields in these and other neurologic disorders.

Effects of whole-body cryotherapy in the management of adhesive capsulitis of the shoulder.

PubMed

Ma, Sang-Yeol; Je, Hyun Dong; Jeong, Ji Hoon; Kim, Hae-Young; Kim, Hyeong-Dong

2013-01-01

To compare 2 different treatment approaches, physical therapy modalities, and joint mobilization versus whole-body cryotherapy (WBC) combined with physical therapy modalities and joint mobilization, for symptoms of adhesive capsulitis (AC) of the shoulder. A randomized trial. Hospital. Patients with AC of the shoulder (N=30). Patients were randomly assigned to 2 groups. The WBC group received physical therapy modalities, passive joint mobilization of the shoulder, and WBC, whereas the non-WBC group received only physical therapy modalities and passive joint mobilization of the shoulder. Visual analog scale (VAS), active range of motion (ROM) of flexion, abduction, internal and external rotation of the shoulder, and the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) were measured before and after the intervention. A statistically significant difference between groups was found for the VAS, active ROM of flexion, abduction, internal rotation, and external rotation, and the ASES with greater improvements in the WBC group (Ps<.01). Overall, both groups showed a significant improvement in all outcome measures and ROM measures from pre to post at a level of P<.01. There is significant improvement with the addition of WBC to treatment interventions in this sample of patients. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Substantial Humic Acid Adsorption to Activated Carbon Air Cathodes Produces a Small Reduction in Catalytic Activity.

PubMed

Yang, Wulin; Watson, Valerie J; Logan, Bruce E

2016-08-16

Long-term operation of microbial fuel cells (MFCs) can result in substantial degradation of activated carbon (AC) air-cathode performance. To examine a possible role in fouling from organic matter in water, cathodes were exposed to high concentrations of humic acids (HA). Cathodes treated with 100 mg L(-1) HA exhibited no significant change in performance. Exposure to 1000 mg L(-1) HA decreased the maximum power density by 14% (from 1310 ± 30 mW m(-2) to 1130 ± 30 mW m(-2)). Pore blocking was the main mechanism as the total surface area of the AC decreased by 12%. Minimization of external mass transfer resistances using a rotating disk electrode exhibited only a 5% reduction in current, indicating about half the impact of HA adsorption was associated with external mass transfer resistance and the remainder was due to internal resistances. Rinsing the cathodes with deionized water did not restore cathode performance. These results demonstrated that HA could contribute to cathode fouling, but the extent of power reduction was relatively small in comparison to large mass of humics adsorbed. Other factors, such as biopolymer attachment, or salt precipitation, are therefore likely more important contributors to long-term fouling of MFC cathodes.

Artemisia capillaris inhibits atopic dermatitis-like skin lesions in Dermatophagoides farinae-sensitized Nc/Nga mice

PubMed Central

2014-01-01

Background Artemisia capillaries Thunb. (AC) has been used to treat inflammatory and hepatic disorders such as hepatic injury, hepatic fibrosis and hepatitis. However, the efficacy of AC against atopic dermatitis (AD), an inflammatory disease, has not been examined. In the present study, AC was evaluated for anti-inflammatory and anti-AD effects using both in vitro and in vivo systems. Methods The contents of six compounds (chlorogenic acid, caffeic acid, isochlorogenic acid A, hyperoside, isoquercitrin and scoparone) in AC were simultaneously assayed using HPLC system. To evaluate the anti-inflammatory effect of AC, NO production was measured in RAW264.7 cell stimulated with 1 μg/mL LPS. Histamine levels were assayed in MC/9 cells stimulated with 50 nM PMA and 1 μM A23187. To examine the role of AC in vivo, AC (10 mg/mouse/day) was topically applied for four weeks the back and ears of Dermatophagoides farinae-sensitized Nc/Nga mice. Protopic ointment (0.1% tacrolimus) was used as a positive control. Results The contents of the six components in AC range from 0.44 to 43.14 mg/g. Chlorogenic acid (21.06 ± 0.08 mg/g) and isochlorogenic acid A (43.14 ± 0.12 mg/g) were major components in AC. AC inhibited NO and histamine production in cells respectively. In D. farinae-sensitized Nc/Nga mice, the topical application of AC reduced dermatitis scores, hemorrhage, hypertrophy and hyperkeratosis of the epidermis in the dorsal skin and ear. The treatment of AC also reduced the plasma levels of histamine (1.5 fold) and IgE (1.4 fold). Conclusions Our results suggest that AC should be explored as a potential therapeutic agent to treat atopic dermatitis and analysis by HPLC will help to improve the quality of AC. PMID:24624888

At the heart of the problem - A person-centred, developmental perspective on the link between alcohol consumption and cardio-vascular events.

PubMed

Lima Passos, Valéria; Klijn, Sven; van Zandvoort, Kevin; Abidi, Latifa; Lemmens, Paul

2017-04-01

The cardio-protective effect of alcohol has been the subject of a long-standing scientific controversy. Emerging evidence remains equivocal, as the validity of the dose-dependent J-shape association is tainted by conceptual, theoretical and methodological problems. A major impediment for a resolution on the matter is the lack of a life-long developmental approach to pinpoint alcohol's specific impact on the risk for cardio-vascular events (CVE). Using retrospective and prospective individual-level data of alcohol consumption (AC) we applied a model-based clustering technique to uncover life-course trajectories of AC and explored their links to CVE. Data stemmed from a random sub-cohort of a large-scale, longitudinal study conducted in the Netherlands (N=2288). Group Based Trajectory Model (GBTM) was applied to extract distinct progressions of AC over time. Stratified by sex, the association between the developmental trajectories and CVE was examined with multiple logistic regression models, with adjustment for traditional risk factors. GBTM analysis laid bare the heterogeneity of AC dynamics over the life-course, reiterating sex differences in drinking habits and CVE risk. AC temporal behaviors during adolescence and adulthood were diverse, but showed relative stability in in middle-age and elderly years. For males, adjusted odds for CVE differed among the uncovered developmental classes. The findings elicited supportive evidence for a J-shape, but with a new twist. Besides moderation the results indicate that onset, timing, duration and stability of AC over the life-course are major aspects to be accounted for when attempting to elucidate alcohol's cardio-vascular role. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

An initial evaluation of potential options for managing riparian reserves of the Aquatic Conservation Strategy of the Northwest Forest Plan

Treesearch

Gordon H. Reeves; Brian R. Pickard; K. Norman Johnson

2016-01-01

The Aquatic Conservation Strategy (ACS) of the Northwest Forest Plan guides management of riparian and aquatic ecosystems on federal lands in western Oregon, western Washington, and northern California. We applied new scientific findings and tools to evaluate two potential options, A and B, for refining interim riparian reserves to meet ACS goals and likely challenges...

Variable frequency inverter for ac induction motors with torque, speed and braking control

NASA Technical Reports Server (NTRS)

Nola, F. J. (Inventor)

1975-01-01

A variable frequency inverter was designed for driving an ac induction motor which varies the frequency and voltage to the motor windings in response to varying torque requirements for the motor so that the applied voltage amplitude and frequency are of optimal value for any motor load and speed requirement. The slip frequency of the motor is caused to vary proportionally to the torque and feedback is provided so that the most efficient operating voltage is applied to the motor. Winding current surge is limited and a controlled negative slip causes motor braking and return of load energy to a dc power source.

Bone regeneration performance of surface-treated porous titanium.

PubMed

Amin Yavari, Saber; van der Stok, Johan; Chai, Yoke Chin; Wauthle, Ruben; Tahmasebi Birgani, Zeinab; Habibovic, Pamela; Mulier, Michiel; Schrooten, Jan; Weinans, Harrie; Zadpoor, Amir Abbas

2014-08-01

The large surface area of highly porous titanium structures produced by additive manufacturing can be modified using biofunctionalizing surface treatments to improve the bone regeneration performance of these otherwise bioinert biomaterials. In this longitudinal study, we applied and compared three types of biofunctionalizing surface treatments, namely acid-alkali (AcAl), alkali-acid-heat treatment (AlAcH), and anodizing-heat treatment (AnH). The effects of treatments on apatite forming ability, cell attachment, cell proliferation, osteogenic gene expression, bone regeneration, biomechanical stability, and bone-biomaterial contact were evaluated using apatite forming ability test, cell culture assays, and animal experiments. It was found that AcAl and AnH work through completely different routes. While AcAl improved the apatite forming ability of as-manufactured (AsM) specimens, it did not have any positive effect on cell attachment, cell proliferation, and osteogenic gene expression. In contrast, AnH did not improve the apatite forming ability of AsM specimens but showed significantly better cell attachment, cell proliferation, and expression of osteogenic markers. The performance of AlAcH in terms of apatite forming ability and cell response was in between both extremes of AnH and AsM. AcAl resulted in significantly larger volumes of newly formed bone within the pores of the scaffold as compared to AnH. Interestingly, larger volumes of regenerated bone did not translate into improved biomechanical stability as AnH exhibited significantly better biomechanical stability as compared to AcAl suggesting that the beneficial effects of cell-nanotopography modulations somehow surpassed the benefits of improved apatite forming ability. In conclusion, the applied surface treatments have considerable effects on apatite forming ability, cell attachment, cell proliferation, and bone ingrowth of the studied biomaterials. The relationship between these properties and the bone-implant biomechanics is, however, not trivial. Copyright © 2014 Elsevier Ltd. All rights reserved.

EPG waveform library for Graphocephala atropunctata (Hemiptera: Cicadellidae): Effect of adhesive, input resistor, and voltage levels on waveform appearance and stylet probing behaviors.

PubMed

Cervantes, Felix A; Backus, Elaine A

2018-05-31

Blue-green sharpshooter, Graphocephala atropunctata, is a native California vector of Xylella fastidiosa (Xf), a foregut-borne bacterium that is the causal agent of Pierce's disease in grapevines. A 3rd-generation, AC-DC electropenetrograph (EPG monitor) was used to record stylet probing and ingestion behaviors of adult G. atropunctata on healthy grapevines. This study presents for the first time a complete, updated waveform library for this species, as well as effects of different electropenetrograph settings and adhesives on waveform appearances. Both AC and DC applied signals were used with input resistor (Ri) levels (amplifier sensitivities) of 10 6 , 10 7 , 10 8 and 10 9  Ohms, as well as two type of adhesives, conducting silver paint and handmade silver glue. Waveform description, characterization of electrical origins (R versus emf components), and proposed biological meanings of waveforms are reported, as well as qualitative differences in waveform appearances observed with different electropenetrograph settings and adhesives. In addition, a quantitative study with AC signal, using two applied voltage levels (50 and 200 mV) and two Ri levels (10 7 and 10 9  Ohms) was performed. Intermediate Ri levels 10 7 and 10 8  Ohms provided EPG waveforms with the greatest amount of information, because both levels captured similar proportions of R and emf components, as supported by appearance, clarity, and definition of waveforms. Similarly, use of a gold wire loop plus handmade silver glue provided more definition of waveforms than a gold wire loop plus commercial conducting silver paint. Qualitative/observational evidence suggested that AC applied signal caused fewer aberrant behaviors/waveforms than DC applied signal. In the quantitative study, behavioral components of the sharpshooter X wave were the most affected by changes in Ri and voltage level. Because the X wave probably represents X. fastidiosa inoculation behavior, future studies of X. fastidiosa inoculation via EPG will require carefully determined instrument settings. An intermediate Ri level such as 10 8  Ohms with low voltage, AC applied signal, and gold wire loop plus silver glue is recommended as the best electropenetrograph methods to conduct future EPG studies of sharpshooter inoculation behaviors on Xf-resistant and -susceptible grapevine. Copyright © 2018. Published by Elsevier Ltd.

De Novo Design and Experimental Characterization of Ultrashort Self-Associating Peptides

PubMed Central

Xue, Bo; Robinson, Robert C.; Hauser, Charlotte A. E.; Floudas, Christodoulos A.

2014-01-01

Self-association is a common phenomenon in biology and one that can have positive and negative impacts, from the construction of the architectural cytoskeleton of cells to the formation of fibrils in amyloid diseases. Understanding the nature and mechanisms of self-association is important for modulating these systems and in creating biologically-inspired materials. Here, we present a two-stage de novo peptide design framework that can generate novel self-associating peptide systems. The first stage uses a simulated multimeric template structure as input into the optimization-based Sequence Selection to generate low potential energy sequences. The second stage is a computational validation procedure that calculates Fold Specificity and/or Approximate Association Affinity (K*association) based on metrics that we have devised for multimeric systems. This framework was applied to the design of self-associating tripeptides using the known self-associating tripeptide, Ac-IVD, as a structural template. Six computationally predicted tripeptides (Ac-LVE, Ac-YYD, Ac-LLE, Ac-YLD, Ac-MYD, Ac-VIE) were chosen for experimental validation in order to illustrate the self-association outcomes predicted by the three metrics. Self-association and electron microscopy studies revealed that Ac-LLE formed bead-like microstructures, Ac-LVE and Ac-YYD formed fibrillar aggregates, Ac-VIE and Ac-MYD formed hydrogels, and Ac-YLD crystallized under ambient conditions. An X-ray crystallographic study was carried out on a single crystal of Ac-YLD, which revealed that each molecule adopts a β-strand conformation that stack together to form parallel β-sheets. As an additional validation of the approach, the hydrogel-forming sequences of Ac-MYD and Ac-VIE were shuffled. The shuffled sequences were computationally predicted to have lower K*association values and were experimentally verified to not form hydrogels. This illustrates the robustness of the framework in predicting self-associating tripeptides. We expect that this enhanced multimeric de novo peptide design framework will find future application in creating novel self-associating peptides based on unnatural amino acids, and inhibitor peptides of detrimental self-aggregating biological proteins. PMID:25010703

Alternating current (AC) iontophoretic transport across human epidermal membrane: effects of AC frequency and amplitude.

PubMed

Yan, Guang; Xu, Qingfang; Anissimov, Yuri G; Hao, Jinsong; Higuchi, William I; Li, S Kevin

2008-03-01

As a continuing effort to understand the mechanisms of alternating current (AC) transdermal iontophoresis and the iontophoretic transport pathways in the stratum corneum (SC), the objectives of the present study were to determine the interplay of AC frequency, AC voltage, and iontophoretic transport of ionic and neutral permeants across human epidermal membrane (HEM) and use AC as a means to characterize the transport pathways. Constant AC voltage iontophoresis experiments were conducted with HEM in 0.10 M tetraethyl ammonium pivalate (TEAP). AC frequencies ranging from 0.0001 to 25 Hz and AC applied voltages of 0.5 and 2.5 V were investigated. Tetraethyl ammonium (TEA) and arabinose (ARA) were the ionic and neutral model permeants, respectively. In data analysis, the logarithm of the permeability coefficients of HEM for the model permeants was plotted against the logarithm of the HEM electrical resistance for each AC condition. As expected, linear correlations between the logarithms of permeability coefficients and the logarithms of resistances of HEM were observed, and the permeability data were first normalized and then compared at the same HEM electrical resistance using these correlations. Transport enhancement of the ionic permeant was significantly larger than that of the neutral permeant during AC iontophoresis. The fluxes of the ionic permeant during AC iontophoresis of 2.5 V in the frequency range from 5 to 1,000 Hz were relatively constant and were approximately 4 times over those of passive transport. When the AC frequency decreased from 5 to 0.001 Hz at 2.5 V, flux enhancement increased to around 50 times over passive transport. While the AC frequency for achieving the full effect of iontophoretic enhancement at low AC frequency was lower than anticipated, the frequency for approaching passive diffusion transport at high frequency was higher than expected from the HEM morphology. These observations are consistent with a transport model of multiple barriers in series and the previous hypothesis that the iontophoresis pathways across HEM under AC behave like a series of reservoirs interconnected by short pore pathways.

Asbestos exposure during renovation and demolition of asbestos-cement clad buildings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, S.K.

External asbestos cement (AC) claddings become weathered after many years by the gradual loss of cement from exposed surfaces; as a result, loosely bound layers enriched with asbestos fibers are formed. Asbestos fibers on such weathered surfaces may be mixtures of chrysotile with amosite or crocidolite. Renovation and demolition of old AC clad buildings could cause asbestos fiber emission, but this has not been investigated in the past. The exposure of workers to asbestos dust during these operations and precautions to minimize exposure now have been investigated at several building sites. Asbestos dust concentrations during water jet cleaning or paintingmore » of weathered AC roofing were approximately 0.1 to 0.2 fibers per milliliter (f/mL). Limited results suggest that concentrations may be reduced substantially by avoiding abrasion of surfaces. Concentrations during AC roof replacement averaged approximately 0.1 f/mL and were reduced markedly by employing more careful work procedures. Asbestos dust concentrations during demolition by removal of whole sheets averaged 0.3 to 0.6 f/mL for roofs and less than 0.1 f/mL for walls, reflecting the significant differences in extent of weathering between these elements. Suppression of asbestos emissions from roof sheets by wetting or sealing of weathered surfaces was not predictable because of the occurrence of asbestos fibers in dust trapped under sheet laps.« less

Promising efficacy of novel BTK inhibitor AC0010 in mantle cell lymphoma.

PubMed

Yan, Xiao; Zhou, Yile; Huang, Shujuan; Li, Xia; Yu, Mengxia; Huang, Jiansong; Wang, Jinghan; Ma, Zhixin; Jin, Jingrui; Pan, Jiajia; Li, Chenying; Li, Fenglin; Jin, Jie

2018-04-01

We researched into the effect and mechanism of AC0010, a novel BTK inhibitor, in MCL, and compared its efficacy and safety with Ibrutinib to develop a preclinical study for the future therapy of MCL. MTS assay was used to detect the growth inhibition caused by AC0010 and Ibrutinib, respectively, in MCL cell lines (Jeko-1 and JVM-2), primary MCL cells, and normal peripheral lymphocytes. Apoptosis of Jeko-1 and JVM-2 after exposure into AC0010 and Ibrutinib was conducted by flow cytometry; the expression of apoptosis-related proteins was checked by Western blot. q-PCR and Western blot were applied to examine the expression of BTK and p-BTK at mRNA and protein level as well as the BTK-ralated signaling pathways. MCL xenograft was developed to testify the efficacy and safety of AC0010 in vivo. In contrast with Ibrutinib, AC0010 proved to be more toxic to MCL cells in vitro (p < 0.01) with no augment in cytotoxicity to normal peripheral lymphocytes, and it can induce obvious apoptosis in MCL cell lines (p < 0.01) through caspase family and Bcl-2 family. AC0010 at 300 mg/kg can prolong the survival rate in MCL xenograft (p < 0.01). The phosphorylation of BTK is inhibited by AC0010 following simultaneously inhibition of BCR-BTK and PI3K/AKT signaling pathway in MCL cells. AC0010 is a novel BTK inhibitor of great efficacy and safety in MCL.

Sorption of mercury onto waste material derived low-cost activated carbon

NASA Astrophysics Data System (ADS)

Bhakta, Jatindra N.; Rana, Sukanta; Lahiri, Susmita; Munekage, Yukihiro

2017-03-01

The present study was performed to develop the low-cost activated carbon (AC) from some waste materials as potential mercury (Hg) sorbent to remove high amount of Hg from aqueous phase. The ACs were prepared from banana peel, orange peel, cotton fiber and paper wastes by pyrolysis and characterized by analyzing physico-chemical properties and Hg sorption capacity. The Brunauer Emmett and Teller surface areas (cotton 138 m2/g; paper 119 m2/g), micropore surface areas (cotton 65 m2/g; paper 54 m2/g) and major constituent carbon contents (cotton 95.04 %; paper 94.4 %) were higher in ACs of cotton fiber and paper wastes than the rest two ACs. The Hg sorption capacities and removal percentages were greater in cotton and paper wastes-derived ACs compared to those of the banana and orange peels. The results revealed that elevated Hg removal ability of cotton and paper wastes-derived ACs is largely regulated by their surface area, porosity and carbon content properties. Therefore, ACs of cotton and paper wastes were identified as potential sorbent among four developed ACs to remove high amount of Hg from aqueous phase. Furthermore, easily accessible precursor material, simple preparation process, favorable physico-chemical properties and high Hg sorption capacity indicated that cotton and paper wastes-derived ACs could be used as potential and low-cost sorbents of Hg for applying in practical field to control the severe effect of Hg contamination in the aquatic environment to avoid its human and environmental health risks.

Effect of dc field on ac-loss peak in a commercial Bi:2223/Ag tape

NASA Astrophysics Data System (ADS)

Öztürk, Ali; Düzgün, İbrahim; Çelebi, Selahattin

2017-12-01

Measurements of the ac susceptibility in a commercial Bi:2223/Ag tape for some different ac magnetic field amplitudes, Hac, in the presence of bias magnetic field Hdc directed along Hac are reported. It is found that the peak values of the imaginary component of ac susceptibility χ″max versus Hac trace a valley for the orientation where applied field Ha perpendicular to wide face of the tape total. We note that the observation of the valley depends on various parameters such as field dependence parameter n in the critical current density, in the simple power law expression jc = α(T)/Bn, choice of the bias field Hdc together with selected ac field amplitudes Hac, and dimension and geometry of sample studied. Our calculations based on critical state model with jc = α(1 - T/Tcm)p/Bn using the fitting parameters of n = 0.25, p = 2.2, Tcm = 108 K gives quite good results to compare the experimental and calculated curves.

Frequent statistics of link-layer bit stream data based on AC-IM algorithm

NASA Astrophysics Data System (ADS)

Cao, Chenghong; Lei, Yingke; Xu, Yiming

2017-08-01

At present, there are many relevant researches on data processing using classical pattern matching and its improved algorithm, but few researches on statistical data of link-layer bit stream. This paper adopts a frequent statistical method of link-layer bit stream data based on AC-IM algorithm for classical multi-pattern matching algorithms such as AC algorithm has high computational complexity, low efficiency and it cannot be applied to binary bit stream data. The method's maximum jump distance of the mode tree is length of the shortest mode string plus 3 in case of no missing? In this paper, theoretical analysis is made on the principle of algorithm construction firstly, and then the experimental results show that the algorithm can adapt to the binary bit stream data environment and extract the frequent sequence more accurately, the effect is obvious. Meanwhile, comparing with the classical AC algorithm and other improved algorithms, AC-IM algorithm has a greater maximum jump distance and less time-consuming.

Space Charge Modulated Electrical Breakdown

PubMed Central

Li, Shengtao; Zhu, Yuanwei; Min, Daomin; Chen, George

2016-01-01

Electrical breakdown is one of the most important physical phenomena in electrical and electronic engineering. Since the early 20th century, many theories and models of electrical breakdown have been proposed, but the origin of one key issue, that the explanation for dc breakdown strength being twice or higher than ac breakdown strength in insulating materials, remains unclear. Here, by employing a bipolar charge transport model, we investigate the space charge dynamics in both dc and ac breakdown processes. We demonstrate the differences in charge accumulations under both dc and ac stresses and estimate the breakdown strength, which is modulated by the electric field distortion induced by space charge. It is concluded that dc breakdown initializes in the bulk whereas ac breakdown initializes in the vicinity of the sample-electrode interface. Compared with dc breakdown, the lower breakdown strength under ac stress and the decreasing breakdown strength with an increase in applied frequency, are both attributed to the electric field distortion induced by space charges located in the vicinity of the electrodes. PMID:27599577

AC power generation from microbial fuel cells

NASA Astrophysics Data System (ADS)

Lobo, Fernanda Leite; Wang, Heming; Forrestal, Casey; Ren, Zhiyong Jason

2015-11-01

Microbial fuel cells (MFCs) directly convert biodegradable substrates to electricity and carry good potential for energy-positive wastewater treatment. However, the low and direct current (DC) output from MFC is not usable for general electronics except small sensors, yet commercial DC-AC converters or inverters used in solar systems cannot be directly applied to MFCs. This study presents a new DC-AC converter system for MFCs that can generate alternating voltage in any desired frequency. Results show that AC power can be easily achieved in three different frequencies tested (1, 10, 60 Hz), and no energy storage layer such as capacitors was needed. The DC-AC converter efficiency was higher than 95% when powered by either individual MFCs or simple MFC stacks. Total harmonic distortion (THD) was used to investigate the quality of the energy, and it showed that the energy could be directly usable for linear electronic loads. This study shows that through electrical conversion MFCs can be potentially used in household electronics for decentralized off-grid communities.

Modeling of phonon scattering in n-type nanowire transistors using one-shot analytic continuation technique

NASA Astrophysics Data System (ADS)

Bescond, Marc; Li, Changsheng; Mera, Hector; Cavassilas, Nicolas; Lannoo, Michel

2013-10-01

We present a one-shot current-conserving approach to model the influence of electron-phonon scattering in nano-transistors using the non-equilibrium Green's function formalism. The approach is based on the lowest order approximation (LOA) to the current and its simplest analytic continuation (LOA+AC). By means of a scaling argument, we show how both LOA and LOA+AC can be easily obtained from the first iteration of the usual self-consistent Born approximation (SCBA) algorithm. Both LOA and LOA+AC are then applied to model n-type silicon nanowire field-effect-transistors and are compared to SCBA current characteristics. In this system, the LOA fails to describe electron-phonon scattering, mainly because of the interactions with acoustic phonons at the band edges. In contrast, the LOA+AC still well approximates the SCBA current characteristics, thus demonstrating the power of analytic continuation techniques. The limits of validity of LOA+AC are also discussed, and more sophisticated and general analytic continuation techniques are suggested for more demanding cases.

Academic context and perceived mental workload of psychology students.

PubMed

Rubio-Valdehita, Susana; López-Higes, Ramón; Díaz-Ramiro, Eva

2014-01-01

The excessive workload of university students is an academic stressor. Consequently, it is necessary to evaluate and control the workload in education. This research applies the NASA-TLX scale, as a measure of the workload. The objectives of this study were: (a) to measure the workload levels of a sample of 367 psychology students, (b) to group students according to their positive or negative perception of academic context (AC) and c) to analyze the effects of AC on workload. To assess the perceived AC, we used an ad hoc questionnaire designed according to Demand-Control-Social Support and Effort-Reward Imbalance models. Using cluster analysis, participants were classified into two groups (positive versus negative context). The differences between groups show that a positive AC improves performance (p < .01) and reduces feelings of overload (p < .02), temporal demand (p < .02), and nervousness and frustration (p < .001). Social relationships with peers and teachers, student autonomy and result satisfaction were relevant dimensions of the AC (p < .001 in all cases).

The Effect of External Magnetic Fields on the MRT Instability in MagLIF

NASA Astrophysics Data System (ADS)

Hess, Mark; Peterson, Kyle; Weis, Matthew; Lau, Yue Ying

2014-10-01

Recent experiments on MagLIF which incorporate an external B-field suggest that the MRT instability within the liner has a different behavior than without the B-field. Previous work by Chandrasekhar and Harris have illustrated how the MRT growth rate, assuming fixed liner density and fixed acceleration, can change due to the presence of an external B-field. In this work, we show how the growth rate of the MRT instability is dynamically affected by the rapidly varying acceleration, liner density, and surface magnetic field, which is composed of the external B-field and the drive B-field of the liner in the MagLIF experiments. In addition, we also examine the effects of finite liner resistivity on MRT growth, which gives rise to an additional time scale corresponding to magnetic diffusion. We discuss the implications of this result for future MagLIF designs. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

Correlations Between the Contributions of Individual IVS Analysis Centers

NASA Technical Reports Server (NTRS)

Bockmann, Sarah; Artz, Thomas; Nothnagel, Axel

2010-01-01

Within almost all space-geodetic techniques, contributions of different analysis centers (ACs) are combined in order to improve the robustness of the final product. So far, the contributing series are assumed to be independent as each AC processes the observations in different ways. However, the series cannot be completely independent as each analyst uses the same set of original observations and many applied models are subject to conventions used by each AC. In this paper, it is shown that neglecting correlations between the contributing series yields too optimistic formal errors and small, but insignificant, errors in the estimated parameters derived from the adjustment of the combined solution.

Electro-actuated hydrogel walkers with dual responsive legs.

PubMed

Morales, Daniel; Palleau, Etienne; Dickey, Michael D; Velev, Orlin D

2014-03-07

Stimuli responsive polyelectrolyte hydrogels may be useful for soft robotics because of their ability to transform chemical energy into mechanical motion without the use of external mechanical input. Composed of soft and biocompatible materials, gel robots can easily bend and fold, interface and manipulate biological components and transport cargo in aqueous solutions. Electrical fields in aqueous solutions offer repeatable and controllable stimuli, which induce actuation by the re-distribution of ions in the system. Electrical fields applied to polyelectrolyte-doped gels submerged in ionic solution distribute the mobile ions asymmetrically to create osmotic pressure differences that swell and deform the gels. The sign of the fixed charges on the polyelectrolyte network determines the direction of bending, which we harness to control the motion of the gel legs in opposing directions as a response to electrical fields. We present and analyze a walking gel actuator comprised of cationic and anionic gel legs made of copolymer networks of acrylamide (AAm)/sodium acrylate (NaAc) and acrylamide/quaternized dimethylaminoethyl methacrylate (DMAEMA Q), respectively. The anionic and cationic legs were attached by electric field-promoted polyion complexation. We characterize the electro-actuated response of the sodium acrylate hydrogel as a function of charge density and external salt concentration. We demonstrate that "osmotically passive" fixed charges play an important role in controlling the bending magnitude of the gel networks. The gel walkers achieve unidirectional motion on flat elastomer substrates and exemplify a simple way to move and manipulate soft matter devices and robots in aqueous solutions.

Development of magneto-rheologial fluid (MRF) based clutch for output torque control of AC motors

NASA Astrophysics Data System (ADS)

Nguyen, Q. Hung; Do, H. M. Hieu; Nguyen, V. Quoc; Nguyen, N. Diep; Le, D. Thang

2018-03-01

In industry, the AC motor is widely used because of low price, power availability, low cost maintenance. The main disadvantages of AC motors compared to DC motors are difficulty in speed and torque control, requiring expensive controllers with complex control algorithms. This is the basic limitations in the widespread adoption of AC motor systems for industrial automation. One feasible solution for AC motor control is using MRF (magneto-rheological fluid) based clutches (shortly called MR clutches) Although there have been many studies on MR clutches, most of these clutches used traditional configuration with coils wound on the middle cylindrical part and a compotator is used to supply power to the coils. Therefore, this type of MR clutches possesses many disadvantages such as high friction and unstable applied current due to commutator, complex structure which causes difficulty in manufacture, assembly, and maintenance. In addition, the bottleneck problem of magnetic field is also a challenging issue. In this research, we will develop a new type of MR clutches that overcomes the abovementioned disadvantages of traditional MR clutches and more suitable for application in controlling of AC motor. Besides, in this study, speed and torque control system for AC motors using developed MR clutches is designed and experimental validated.

Emerging drugs for allergic conjunctivitis.

PubMed

Ridolo, Erminia; Montagni, Marcello; Caminati, Marco; Senna, Gianenrico; Incorvaia, Cristoforo; Canonica, Giorgio Walter

2014-06-01

Allergic conjunctivitis (AC) is a very common disease, especially in association with allergic rhinitis but may also occur in isolated presentation. The treatment of AC has long been based on antihistamines, cromones and topical corticosteroids, but none of these drugs completely abolishes the clinical expression of AC. The development of new drugs for AC is analyzed highlighting the recent insights into the pathophysiological mechanisms of the disease. The major aim of development of drugs for AC is to have agents able to prevent the inflammatory effects of the interaction between the allergen and the specific IgE antibodies on mast cell surface. This may be obtained by blocking the effects of histamine (the main mediator of early allergic response) by H1-receptor antagonists, inhibiting the release of soluble factors able to recruit inflammatory cells (that sustain prolonged inflammation) by mast-cell stabilizers, inhibiting the effects of single mediators, inducing tolerance to the allergen by specific immunotherapy or even acting on factors related to activation and differentiation of T lymphocytes such as the toll-like receptors. AC is an underestimated disease for which there is a search of more effective treatments. The availability of the drugs under current evaluation will allow more refined therapeutic strategies to apply according to the characteristics and the clinical severity of AC.

Combined Effect of Alternating Current Interference and Cathodic Protection on Pitting Corrosion and Stress Corrosion Cracking Behavior of X70 Pipeline Steel in Near-Neutral pH Environment.

PubMed

Wang, Liwei; Cheng, Lianjun; Li, Junru; Zhu, Zhifu; Bai, Shuowei; Cui, Zhongyu

2018-03-22

Influence of alternating current (AC) on pitting corrosion and stress corrosion cracking (SCC) behavior of X70 pipeline steel in the near-neutral pH environment under cathodic protection (CP) was investigated. Both corrosion and SCC are inhibited by -0.775 V SCE CP without AC interference. With the superimposition of AC current (1-10 mA/cm²), the direct current (DC) potential shifts negatively under the CP of -0.775 V SCE and the cathodic DC current decreases and shifts to the anodic direction. Under the CP potential of -0.95 V SCE and -1.2 V SCE , the applied AC current promotes the cathodic reaction and leads to the positive shift of DC potential and increase of cathodic current. Local anodic dissolution occurs attributing to the generated anodic current transients in the positive half-cycle of the AC current, resulting in the initiation of corrosion pits (0.6-2 μm in diameter). AC enhances the SCC susceptibility of X70 steel under -0.775 V SCE CP, attributing to the promotion of anodic dissolution and hydrogen evolution. Even an AC current as low as 1 mA/cm² can enhance the SCC susceptibility.

Vortex flux dynamics and harmonic ac magnetic response of Ba(Fe 0.94Ni 0.06) 2As 2 bulk superconductor

DOE PAGES

Nikolo, Martin; Zapf, Vivien S.; Singleton, John; ...

2016-07-22

Vortex dynamics and nonlinear ac response are studied in a Ba(Fe 0.94Ni 0.06) 2As 2( T c= 18.5 K) bulk superconductor in magnetic fields up to 12 T via ac susceptibility measurements of the first ten harmonics. A comprehensive study of the ac magnetic susceptibility and its first ten harmonics finds shifts to higher temperatures with increasing ac measurement frequencies (10 to 10,000 Hz) for a wide range of ac (1, 5, and 10 Oe) and dc fields (0 to 12 T). The characteristic measurement time constant t1 is extracted from the exponential fit of the data and linked tomore » vortex relaxation. The Anderson-Kim Arrhenius law is applied to determine flux activation energy E a/k as a function dc magnetic field. The de-pinning, or irreversibility lines, were determined by a variety of methods and extensively mapped. The ac response shows surprisingly weak higher harmonic components, suggesting weak nonlinear behavior. Lastly, our data does not support the Fisher model; we do not see an abrupt vortex glass to vortex liquid transition and the resistivity does not drop to zero, although it appears to approach zero exponentially.« less

Diagnostics of the Fermilab Tevatron using an AC dipole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyamoto, Ryoichi

2008-08-01

The Fermilab Tevatron is currently the world's highest energy colliding beam facility. Its counter-rotating proton and antiproton beams collide at 2 TeV center-of-mass. Delivery of such intense beam fluxes to experiments has required improved knowledge of the Tevatron's beam optical lattice. An oscillating dipole magnet, referred to as an AC dipole, is one of such a tool to non-destructively assess the optical properties of the synchrotron. We discusses development of an AC dipole system for the Tevatron, a fast-oscillating (f ~ 20 kHz) dipole magnet which can be adiabatically turned on and off to establish sustained coherent oscillations of themore » beam particles without affecting the transverse emittance. By utilizing an existing magnet and a higher power audio amplifier, the cost of the Tevatron AC dipole system became relatively inexpensive. We discuss corrections which must be applied to the driven oscillation measurements to obtain the proper interpretation of beam optical parameters from AC dipole studies. After successful operations of the Tevatron AC dipole system, AC dipole systems, similar to that in the Tevatron, will be build for the CERN LHC. We present several measurements of linear optical parameters (beta function and phase advance) for the Tevatron, as well as studies of non-linear perturbations from sextupole and octupole elements.« less

Third harmonic ac susceptibility of superconductors with finite thickness

NASA Astrophysics Data System (ADS)

Qin, M. J.; Ong, C. K.

Third harmonic ac susceptibility of superconducting strips with finite thickness in perpendicularly applied magnetic field Ha = H0 sin(ω t) have been calculated. The flux creep effect is taken into account by using a power-law electric field E( j) = Ec( j/ jc) n. Results for different thicknesses and creep exponents n have been derived and compared to the results derived from the Bean critical state model.

Imaging ac losses in superconducting films via scanning Hall probe microscopy

NASA Astrophysics Data System (ADS)

Dinner, Rafael B.; Moler, Kathryn A.; Feldmann, D. Matthew; Beasley, M. R.

2007-04-01

Various local probes have been applied to understanding current flow through superconducting films, which are often surprisingly inhomogeneous. Here, we show that magnetic imaging allows quantitative reconstruction of both current density J and electric field E resolved in time and space in a film carrying subcritical ac current. Current reconstruction entails inversion of the Biot-Savart law, while electric fields are reconstructed using Faraday’s law. We describe the corresponding numerical procedures, largely adapting existing work to the case of a strip carrying ac current, but including other methods of obtaining the complete electric field from the inductive portion determined by Faraday’s law. We also delineate the physical requirements behind the mathematical transformations. We then apply the procedures to images of a strip of YBa2Cu3O7-δ carrying an ac current at 400Hz . Our scanning Hall probe microscope produces a time series of magnetic images of the strip with 1μm spatial resolution and 25μs time resolution. Combining the reconstructed J and E , we obtain a complete characterization including local critical current density, E-J curves, and power losses. This analysis has a range of applications from fundamental studies of vortex dynamics to practical coated conductor development.

ARC-1980-AC80-0107-2

NASA Image and Video Library

1980-02-06

The first solid rocket booster solid motor segemnts to arrive at KSC, the left and right hand aft segments are off-loaded into High Bay 4 in the Vehicle Assembly Building and mated to their respective SRB aft skirts. The two aft assemblies will support the entire 150 foot tall solid boosters, in turn supporting the external tank and Orbiter Columbia on the Mobile Launcher Platform, for the first orbital flight test of the Space Shuttle.

ARC-1980-AC80-0107-3

NASA Image and Video Library

1980-02-06

The first solid rocket booster solid motor segemnts to arrive at KSC, the left and right hand aft segments are off-loaded into High Bay 4 in the Vehicle Assembly Building and mated to their respective SRB aft skirts. The two aft assemblies will support the entire 150 foot tall solid boosters, in turn supporting the external tank and Orbiter Columbia on the Mobile Launcher Platform, for the first orbital flight test of the Space Shuttle.

A linear magnetic motor and generator

NASA Technical Reports Server (NTRS)

Studer, P. A.

1980-01-01

In linear magnetic motor and generator suitable for remote and hostile environments, magnetic forces drive reciprocating shaft along its axis. Actuator shaft is located in center of cylindrical body and may be supported by either contacting or noncontacting bearings. When device operates as bidirectional motor, drive coil selectively adds and subtracts magnetic flux to and from flux paths, producing forces that drive actuator along axis. When actuator is driven by external reciprocating engine, device becomes ac generator.

76 FR 33752 - Notice of Availability of the External Review Draft of the Guidance for Applying Quantitative...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-09

... External Review Draft of the Guidance for Applying Quantitative Data To Develop Data-Derived Extrapolation... Applying Quantitative Data to Develop Data-Derived Extrapolation Factors for Interspecies and Intraspecies... Applying Quantitative Data to Develop Data-Derived Extrapolation Factors for Interspecies and Intraspecies...

Magnetic nanorings and manipulation of nanowires

NASA Astrophysics Data System (ADS)

Chien, C. L.

2006-03-01

The properties of nanoscale entities, such as nanorings and nanowires, and the response of such entities to external fields are dictated by their geometrical shapes and sizes, which can be manipulated by fabrication. We have developed a method for fabricating a large number of nanorings (10^10) of different sizes in the range of 100 nm and ring cross sections. During magnetic reversal, both the vortex state and the rotating onion state appear with different proportions, which depend on the ring diameter, ring cross section, and the profile of the ring cross section. In the case of nanowires in suspension, the large aspect ratio of the nanowires can be exploited for manipulation despite extremely small Reynolds numbers of 10-5. Using AC electric field applied to microelectrodes, both magnetic and non-magnetic nanowires can be efficiently assembled into desired patterns. We also demonstrate rotation of nanowires with precisely controlled rotation speed and chirality, as well as an electrically driven nanowire micromotor a few in size. In collaboration with F. Q. Zhu, D. L. Fan, O. Tchernyshyov, R. C. Cammarata (Johns Hopkins University) and X. C. Zhu and J. G. Zhu (Carnegie-Mellon University).

In-situ USAXS/SAXS Investigation of Tunable Structural Color in Amorphous Photonic Crystals During Electrophoretic Deposition

NASA Astrophysics Data System (ADS)

Bukosky, Scott; Hammons, Joshua; Han, Jinkyu; Freyman, Megan; Lee, Elaine; Cook, Caitlyn; Kuntz, Joshua; Worsley, Marcus; Han, Thomas Yong; Ristenpart, William; Pascall, Andrew

2017-11-01

Amorphous photonic crystals (APCs) formed via electrophoretic deposition (EPD) exhibit non-iridescent, angle-independent, structural colors believed to arise from changes in the particle-particle interactions and inter-particle spacing, representing a potential new paradigm for display technologies. However, particle dynamics on nanometer length scales that govern the displayed color, crystallinity, and other characteristics of the photonic structures, are not well understood. In this work, in-situ USAXS/SAXS studies of three-dimensional colloidal particle arrays were performed in order to identify their structural response to applied external electric fields. These results were compared to simultaneously acquired UV-Vis spectra to tie the overall electrically induced structure of the APCs directly to the observed changes in visible color. The structural evolution of the APCs provides new information regarding the correlation between nano-scale particle-particle interactions and the corresponding optical response. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-736068.

Locked-mode avoidance and recovery without external momentum input

NASA Astrophysics Data System (ADS)

Delgado-Aparicio, L.; Gates, D. A.; Wolfe, S.; Rice, J. E.; Gao, C.; Wukitch, S.; Greenwald, M.; Hughes, J.; Marmar, E.; Scott, S.

2014-10-01

Error-field-induced locked-modes (LMs) have been studied in C-Mod at ITER toroidal fields without NBI fueling and momentum input. The use of ICRH heating in synch with the error-field ramp-up resulted in a successful delay of the mode-onset when PICRH > 1 MW and a transition into H-mode when PICRH > 2 MW. The recovery experiments consisted in applying ICRH power during the LM non-rotating phase successfully unlocking the core plasma. The ``induced'' toroidal rotation was in the counter-current direction, restoring the direction and magnitude of the toroidal flow before the LM formation, but contrary to the expected Rice-scaling in the co-current direction. However, the LM occurs near the LOC/SOC transition where rotation reversals are commonly observed. Once PICRH is turned off, the core plasma ``locks'' at later times depending on the evolution of ne and Vt. This work was performed under US DoE contracts including DE-FC02-99ER54512 and others at MIT and DE-AC02-09CH11466 at PPPL.

Characterization on performance of micromixer using DC-biased AC electroosmosis

NASA Astrophysics Data System (ADS)

Park, Bi-O.; Song, Simon

2010-11-01

An active micromixer using DC-biased AC-Electroosmosis (ACEO) is investigated to figure out the effects of design parameters on the mixing performance. The mixer consists of a straight microchannel, with a cross section of 60 x 100 μm, and gold electrode pairs fabricated in the microchannel. The design parameters include the number of electrode pairs, flow rate, DC-biased voltage, AC voltage and AC frequency. First, we found that a mixing index became 80% 100 μm downstream of a single electrode pair with a length of 2 mm when applying a 25Vpp, 2.0 VDC, 100 kHz sine signal to the electrodes. With decreasing AC frequency, the mixing index is affected little. But the mixing index significantly increases with increasing either DC-biased voltage or AC voltage. Also, we were able to increase the mixing index up to 90% by introducing alternating vortices with multiple electrode pairs. Finally, we discovered that the mixing index decreases as the flow rate increases in the microchannel, and there is an optimal number of electrode pairs with respect to a flow rate. Detailed quantitative measurement results will be presented at the meeting.

Electroporation of cells using EM induction of ac fields by a magnetic stimulator

NASA Astrophysics Data System (ADS)

Chen, C.; Evans, J. A.; Robinson, M. P.; Smye, S. W.; O'Toole, P.

2010-02-01

This paper describes a method of effectively electroporating mammalian cell membranes with pulsed alternating-current (ac) electric fields at field strengths of 30-160 kV m-1. Although many in vivo electroporation protocols entail applying square wave or monotonically decreasing pulses via needles or electrode plates, relatively few have explored the use of pulsed ac fields. Following our previous study, which established the effectiveness of ac fields for electroporating cell membranes, a primary/secondary coil system was constructed to produce sufficiently strong electric fields by electromagnetic induction. The primary coil was formed from the applicator of an established transcranial magnetic stimulation (TMS) system, while the secondary coil was a purpose-built device of a design which could eventually be implanted into tissue. The effects of field strength, pulse interval and cumulative exposure time were investigated using microscopy and flow cytometry. Results from experiments on concentrated cell suspensions showed an optimized electroporation efficiency of around 50%, demonstrating that electroporation can be practicably achieved by inducing such pulsed ac fields. This finding confirms the possibility of a wide range of in vivo applications based on magnetically coupled ac electroporation.

Wastewater treatment--adsorption of organic micropollutants on activated HTC-carbon derived from sewage sludge.

PubMed

Kirschhöfer, Frank; Sahin, Olga; Becker, Gero C; Meffert, Florian; Nusser, Michael; Anderer, Gilbert; Kusche, Stepan; Klaeusli, Thomas; Kruse, Andrea; Brenner-Weiss, Gerald

2016-01-01

Organic micropollutants (MPs), in particular xenobiotics and their transformation products, have been detected in the aquatic environment and the main sources of these MPs are wastewater treatment plants. Therefore, an additional cleaning step is necessary. The use of activated carbon (AC) is one approach to providing this additional cleaning. Industrial AC derived from different carbonaceous materials is predominantly produced in low-income countries by polluting processes. In contrast, AC derived from sewage sludge by hydrothermal carbonization (HTC) is a regional and sustainable alternative, based on waste material. Our experiments demonstrate that the HTC-AC from sewage sludge was able to remove most of the applied MPs. In fact more than 50% of sulfamethoxazole, diclofenac and bezafibrate were removed from artificial water samples. With the same approach carbamazepine was eliminated to nearly 70% and atrazine more than 80%. In addition a pre-treated (phosphorus-reduced) HTC-AC was able to eliminate 80% of carbamazepine and diclofenac. Atrazine, sulfamethoxazole and bezafibrate were removed to more than 90%. Experiments using real wastewater samples with high organic content (11.1 g m(-3)) succeeded in proving the adsorption capability of phosphorus-reduced HTC-AC.

Internal friction and dislocation collective pinning in disordered quenched solid solutions

NASA Astrophysics Data System (ADS)

D'Anna, G.; Benoit, W.; Vinokur, V. M.

1997-12-01

We introduce the collective pinning of dislocations in disordered quenched solid solutions and calculate the macroscopic mechanical response to a small dc or ac applied stress. This work is a generalization of the Granato-Lücke string model, able to describe self-consistently short and long range dislocation motion. Under dc applied stress the long distance dislocation creep has at the microscopic level avalanche features, which result in a macroscopic nonlinear "glassy" velocity-stress characteristic. Under ac conditions the model predicts, in addition to the anelastic internal friction relaxation in the high frequency regime, a linear internal friction background which remains amplitude-independent down to a crossover frequency to a strongly nonlinear internal friction regime.

Study of the allergenic potential of Bacillus thuringiensis Cry1Ac toxin following intra-gastric administration in a murine model of food-allergy.

PubMed

Santos-Vigil, Karla I; Ilhuicatzi-Alvarado, Damaris; García-Hernández, Ana L; Herrera-García, Juan S; Moreno-Fierros, Leticia

2018-06-07

Cry1Ac toxin, from Bacillus thuringiensis, is widely used as a biopesticide and expressed in genetically modified (GM) plants used for human and animal consumption. Since Cry1Ac is also immunogenic and able to activate macrophages, it is crucial to thoroughly evaluate the immunological effects elicited after intra-gastric administration. The allergenic potential of purified Cry1Ac was assessed and compared with that induced in a murine model of food-allergy to ovalbumin (OVA), in which animals are sensitized with the adjuvant Cholera toxin (CT). Mice were weekly intragastrically administered with: i) vehicle phosphate-buffered saline (PBS), ii) OVA, iii) OVA plus CT iv) Cry1Ac or v) OVA plus Cry1Ac. Seven weeks after, mice were intragastrically challenged and allergic reactions along with diverse allergy related immunological parameters were evaluated at systemic and intestinal level. The groups immunized with, Cry1Ac, OVA/Cry1Ac or OVA/CT developed moderate allergic reactions, induced significant IgE response and increased frequencies of intestinal granulocytes, IgE+ eosinophils and IgE+ lymphocytes. These same groups also showed colonic lymphoid hyperplasia, notably in humans, this has been associated with food allergy and intestinal inflammation. Although the adjuvant and allergenic potential of CT were higher than the effects of Cry1Ac, the results show that applied intra-gastrically at 50 μg doses, Cry1Ac is immunogenic, moderately allergenic and able to provoke intestinal lymphoid hyperplasia. Moreover, Cry1Ac is also able to induce anaphylaxis, since when mice were intragastrically sensitized with increasing doses of Cry1Ac, with every dose tested, a significant drop in rectal temperature was recorded after intravenous challenge. Copyright © 2018 Elsevier B.V. All rights reserved.

Modest increase in risk of acute coronary syndrome associated with morphine use in cancer patients: a population-based nested case-control study.

PubMed

Lee, Cynthia Wei-Sheng; Muo, Chih-Hsin; Liang, Ji-An; Sung, Fung-Chang; Kao, Chia-Hung

2014-06-01

Morphine is widely used for pain management in cancer patients. Use of heroin, a morphine derivative, is a risk factor for acute coronary syndrome (ACS). This study investigates the risk of ACS associated with morphine use by comparing the incidence of ACS in cancer patients treated with and without morphine. This is a population-based nested case-control study using the Longitudinal Health Insurance Database 2000 in Taiwan. In total, 31,384 patients on the database were diagnosed with cancer without prior history of ACS during 1998-2010. In this cohort, 499 patients subsequently developed ACS and 30,885 patients did not. The 499 patients were designated as the ACS group; controls were selected from the remaining 30,885 patients and matched 3:1 to each case for age, sex, year of cancer diagnosis, and index year. Logistic regression was used to estimate the odds ratios and 95% confidence intervals, and the multivariable model was applied to control for age, sex, and Charlson comorbidity score. Cancer patients who received morphine had a 32% higher risk of developing ACS than non-morphine users. This increase in risk was significant when evaluating the overall cancer patients, but non-significant when evaluating any specific cancer type. The risk of ACS increased significantly with increasing morphine dosage (to ≥65 mg/y). Morphine treatment is associated with a modest increase in risk of ACS in patients with malignancy, but this association displays low significance in specific cancer types. Copyright © 2014 Elsevier Ltd. All rights reserved.

Stress-only myocardial perfusion scintigraphy: a prospective study on the accuracy and observer agreement with quantitative coronary angiography as the gold standard.

PubMed

Ejlersen, June A; May, Ole; Mortensen, Jesper; Nielsen, Gitte L; Lauridsen, Jeppe F; Allan, Johansen

2017-11-01

Patients with normal stress perfusion have an excellent prognosis. Prospective studies on the diagnostic accuracy of stress-only scans with contemporary, independent examinations as gold standards are lacking. A total of 109 patients with typical angina and no previous coronary artery disease underwent a 2-day stress (exercise)/rest, gated, and attenuation-corrected (AC), 99m-technetium-sestamibi perfusion study, followed by invasive coronary angiography. The stress datasets were evaluated twice by four physicians with two different training levels (expert and novice): familiar and unfamiliar with AC. The two experts also made a consensus reading of the integrated stress-rest datasets. The consensus reading and quantitative data from the invasive coronary angiography were applied as reference methods. The sensitivity/specificity were 0.92-1.00/0.73-0.90 (reference: expert consensus reading), 0.93-0.96/0.63-0.82 (reference: ≥1 stenosis>70%), and 0.75-0.88/0.70-0.88 (reference: ≥1 stenosis>50%). The four readers showed a high and fairly equal sensitivity independent of their familiarity with AC. The expert familiar with AC had the highest specificity independent of the reference method. The intraobserver and interobserver agreements on the stress-only readings were good (readers without AC experience) to excellent (readers with AC experience). AC stress-only images yielded a high sensitivity independent of the training level and experience with AC of the nuclear physician, whereas the specificity correlated positively with both. Interobserver and intraobserver agreements tended to be the best for physicians with AC experience.

Enhanced biochars can match activated carbon performance in sediments with high native bioavailability and low final porewater PCB concentrations.

PubMed

Gomez-Eyles, Jose L; Ghosh, Upal

2018-07-01

A bench scale study was conducted to evaluate the effectiveness of in situ amendments to reduce the bioavailability of pollutants in sediments from a site impacted with polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and cadmium. The amendments tested included fine and coarse coal-based activated carbons (AC), an enhanced pinewood derived biochar (EPB), organoclay, and coke dosed at 5% of sediment dry weight. Strong reductions in total PCB porewater concentrations were observed in sediments amended with the fine AC (94.9-99.5%) and EPB (99.6-99.8%). More modest reductions were observed for the coarse AC, organoclay, and coke. Strong reductions in porewater PCB concentrations were reflected in reductions in total PCB bioaccumulation in fresh water oligochaetes for both the fine AC (91.9-96.0%) and EPB (96.1-96.3%). Total PAH porewater concentrations were also greatly reduced by the fine AC (>96.1%) and EPB (>97.8%) treatments. EPB matched or slightly outperformed the fine AC throughout the study, despite sorption data indicating a much stronger affinity of PCBs for the fine AC. Modeling EPB and fine AC effectiveness on other sediments confirmed the high effectiveness of the EPB was due to the very low final porewater concentrations and differences in the native bioavailability between sediments. However, low bulk density and poor settling characteristics make biochars difficult to apply in an aquatic setting. Neither the EPB nor the fine AC amendments were able to significantly reduce Cd bioavailability. Copyright © 2018 Elsevier Ltd. All rights reserved.

The performance of a mobile air conditioning system with a water cooled condenser

NASA Astrophysics Data System (ADS)

Di Battista, Davide; Cipollone, Roberto

2015-11-01

Vehicle technological evolution lived, in recent years, a strong acceleration due to the increased awareness of environmental issues related to pollutants and climate altering emissions. This resulted in a series of international regulations on automotive sector which put technical challenges that must consider the engine and the vehicle as a global system, in order to improve the overall efficiency of the system. The air conditioning system of the cabin, for instance, is the one of the most important auxiliaries in a vehicle and requires significant powers. Its performances can be significantly improved if it is integrated within the engine cooling circuit, eventually modified with more temperature levels. In this paper, the Authors present a mathematical model of the A/C system, starting from its single components: compressors, condenser, flush valve and evaporator and a comparison between different refrigerant fluid. In particular, it is introduced the opportunity to have an A/C condenser cooled by a water circuit instead of the external air linked to the vehicle speed, as in the actual traditional configuration. The A/C condenser, in fact, could be housed on a low temperature water circuit, reducing the condensing temperature of the refrigeration cycle with a considerable efficiency increase.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaffner, D. A.; Carter, T. A.; Rossi, G. D.

Continuous control over azimuthal flow and shear in the edge of the Large Plasma Device (LAPD) [W. Gekelman et al., Rev. Sci. Instr. 62, 2875 (1991)] has been achieved using a biasable limiter. This flow control has allowed a careful study of the effect of flow shear on pressure-gradient-driven turbulence and particle transport in LAPD. The combination of externally controllable shear in a turbulent plasma along with the detailed spatial diagnostic capabilities on LAPD makes the experiment a useful testbed for validation of shear suppression models. Motivated by these models, power-law fits are made to the density and radial velocitymore » fluctuation amplitudes, particle flux, density-potential crossphase, and radial correlation length. The data show a break in the trend of these quantities when the shearing rate (γ{sub s}=∂V{sub θ}/∂r) is comparable to the turbulent decorrelation rate (1/τ{sub ac}). No one model captures the trends in the all turbulent quantities for all values of the shearing rate, but some models successfully match the trend in either the weak (γ{sub s}τ{sub ac}<1) or strong (γ{sub s}τ{sub ac}>1) shear limits.« less

Hyper-Transcranial Alternating Current Stimulation: Experimental Manipulation of Inter-Brain Synchrony

PubMed Central

Szymanski, Caroline; Müller, Viktor; Brick, Timothy R.; von Oertzen, Timo; Lindenberger, Ulman

2017-01-01

We walk together, we watch together, we win together: Interpersonally coordinated actions are omnipresent in everyday life, yet the associated neural mechanisms are not well understood. Available evidence suggests that the synchronization of oscillatory activity across brains may provide a mechanism for the temporal alignment of actions between two or more individuals. In an attempt to provide a direct test of this hypothesis, we applied transcranial alternating current stimulation simultaneously to two individuals (hyper-tACS) who were asked to drum in synchrony at a set pace. Thirty-eight female-female dyads performed the dyadic drumming in the course of 3 weeks under three different hyper-tACS stimulation conditions: same-phase-same-frequency; different-phase-different-frequency; sham. Based on available evidence and theoretical considerations, stimulation was applied over right frontal and parietal sites in the theta frequency range. We predicted that same-phase-same-frequency stimulation would improve interpersonal action coordination, expressed as the degree of synchrony in dyadic drumming, relative to the other two conditions. Contrary to expectations, both the same-phase-same-frequency and the different-phase-different-frequency conditions were associated with greater dyadic drumming asynchrony relative to the sham condition. No influence of hyper-tACS on behavioral performance was seen when participants were asked to drum separately in synchrony to a metronome. Individual and dyad preferred drumming tempo was also unaffected by hyper-tACS. We discuss limitations of the present version of the hyper-tACS paradigm, and suggest avenues for future research. PMID:29167638

Steroid Injection Versus Physiotherapy for Patients With Adhesive Capsulitis of the Shoulder

PubMed Central

Sun, Yaying; Lu, Shuai; Zhang, Peng; Wang, Zhaohui; Chen, Jiwu

2016-01-01

Abstract To compare the effect of steroid injection and physiotherapy for patients with adhesive capsulitis of the shoulder (ACS). An electronic search was performed on Pubmed, Embase, and Cochrane library, and reference lists were also reviewed for randomized controlled trials (RCTs) comparing steroid injection and physiotherapy for patients with ACS. The quality of included studies were assessed using PEDro scale. Standardized mean differences (SMDs) and 95% confidence interval (CI) were used for comparisons. The primary outcome was functional improvement. Nine RCTs including 453 patients were identified. From 6–7 weeks to 24–26 weeks postintervention, no superiority was noted in favor of either steroid injection or physiotherapy for functional improvement (SMD 0.28; 95% CI −0.01–0.58; P = 0.06) or pain relief (SMD −0.10; 95% CI −0.70–0.50; P = 0.75). Steroid injection provided more improvement in passive external rotation at 24 to 26 weeks (3 studies, SMD 0.42; 95% CI 0.11–0.72; P = 0.007) but not at 6 to 7 weeks (4 studies, SMD 0.63; 95% CI 0.36–0.89; P = 0.32) or 12 to 16 weeks (3 studies, SMD −0.07; 95% CI −0.79–0.65; P = 0.85). Steroid injection was as safe as physiotherapy for patients with ACS (risk ratio 0.94; 95% CI 0.67–1.31). Both steroid injection and physiotherapy are equally effective for patients with ACS. One steroid injection might be the 1st choice for ACS. Results should be interpreted with caution due to the heterogeneity among the studies. PMID:27196452

Quantitative study of electrophoretic and electroosmotic enhancement during alternating current iontophoresis across synthetic membranes.

PubMed

Yan, Guang; Li, S Kevin; Peck, Kendall D; Zhu, Honggang; Higuchi, William I

2004-12-01

One of the primary safety and tolerability limitations of direct current iontophoresis is the potential for electrochemical burns associated with the necessary current densities and/or application times required for effective treatment. Alternating current (AC) transdermal iontophoresis has the potential to eliminate electrochemical burns that are frequently observed during direct current transdermal iontophoresis. Although it has been demonstrated that the intrinsic permeability of skin can be increased by applying low-to-moderate AC voltages, transdermal transport phenomena and enhancement under AC conditions have not been systematically studied and are not well understood. The aim of the present work was to study the fundamental transport mechanisms of square-wave AC iontophoresis using a synthetic membrane system. The model synthetic membrane used was a composite Nuclepore membrane. AC frequencies ranging from 20 to 1000 Hz and AC fields ranging from 0.25 to 0.5 V/membrane were investigated. A charged permeant, tetraethyl ammonium, and a neutral permeant, arabinose, were used. The transport studies showed that flux was enhanced by increasing the AC voltage and decreasing AC frequency. Two theoretical transport models were developed: one is a homogeneous membrane model; the other is a heterogeneous membrane model. Experimental transport data were compared with computer simulations based on these models. Excellent agreement between model predictions and experimental data was observed when the data were compared with the simulations from the heterogeneous membrane model. (c) 2004 Wiley-Liss, Inc. and the American Pharmacists Association

Preparation of desiccation-resistant aquatic-living Nostoc flagelliforme (Cyanophyceae) for potential ecological application.

PubMed

Gao, Xiang; Yang, Yi-Wen; Cui, Li-Juan; Zhou, De-Bao; Qiu, Bao-Sheng

2015-11-01

Nostoc flagelliforme is a terrestrial edible cyanobacterium that grows in arid and semi-arid steppes. The continued over-exploitation in the last century has led to a sharp decline of this resource and a severe deterioration of the steppe ecology. Liquid-cultured N. flagelliforme serves as promising algal 'seeds' for resource restoration. In this study, macroscopic (or visible) aquatic-living colonies (MaACs) of N. flagelliforme were developed under weak light and high nitrogen conditions. In a 24 day shake-flask culture, MaACs were propagated by about 4.5-fold in biomass without loss of their macro-morphology; at the same time, the addition of weak UV-B treatment resulted in slightly bigger MaACs. Polyvinylpyrrolidone (PVP) k30, a water-soluble polymer, was used to generate the coating around MaACs, and after full desiccation, the coated MaACs could recover their photosynthetic physiological activity when rehydrated, with 4% PVP k30 for coating being most effective. In contrast, PVP k30-coated microscopic aquatic-living colonies of N. flagelliforme and non-coated MaACs showed no resistance to full desiccation. The macroscopic morphology or structure of MaACs should be crucial for the formation of protection by PVP k30 coating. PVP k30-coated MaACs were more approaching to actual application for resource restoration. © 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Fiber-Optic Bio-sniffer (Biochemical Gas Sensor) Using Reverse Reaction of Alcohol Dehydrogenase for Exhaled Acetaldehyde.

PubMed

Iitani, Kenta; Chien, Po-Jen; Suzuki, Takuma; Toma, Koji; Arakawa, Takahiro; Iwasaki, Yasuhiko; Mitsubayashi, Kohji

2018-02-23

Volatile organic compounds (VOCs) exhaled in breath have huge potential as indicators of diseases and metabolisms. Application of breath analysis for disease screening and metabolism assessment is expected since breath samples can be noninvasively collected and measured. In this research, a highly sensitive and selective biochemical gas sensor (bio-sniffer) for gaseous acetaldehyde (AcH) was developed. In the AcH bio-sniffer, a reverse reaction of alcohol dehydrogenase (ADH) was employed for reducing AcH to ethanol and simultaneously consuming a coenzyme, reduced form of nicotinamide adenine dinucleotide (NADH). The concentration of AcH can be quantified by fluorescence detection of NADH that was consumed by reverse reaction of ADH. The AcH bio-sniffer was composed of an ultraviolet light-emitting diode (UV-LED) as an excitation light source, a photomultiplier tube (PMT) as a fluorescence detector, and an optical fiber probe, and these three components were connected with a bifurcated optical fiber. A gas-sensing region of the fiber probe was developed with a flow-cell and an ADH-immobilized membrane. In the experiment, after optimization of the enzyme reaction conditions, the selectivity and dynamic range of the AcH bio-sniffer were investigated. The AcH bio-sniffer showed a short measurement time (within 2 min) and a broad dynamic range for determination of gaseous AcH, 0.02-10 ppm, which encompassed a typical AcH concentration in exhaled breath (1.2-6.0 ppm). Also, the AcH bio-sniffer exhibited a high selectivity to gaseous AcH based on the specificity of ADH. The sensor outputs were observed only from AcH-contained standard gaseous samples. Finally, the AcH bio-sniffer was applied to measure the concentration of AcH in exhaled breath from healthy subjects after ingestion of alcohol. As a result, a significant difference of AcH concentration between subjects with different aldehyde dehydrogenase type 2 (ALDH2) phenotypes was observed. The AcH bio-sniffer can be used for breath measurement, and further, an application of breath analysis-based disease screening or metabolism assessment can be expected due to the versatility of its detection principle, which allows it to measure other VOCs by using NADH-dependent dehydrogenases.

Average absorption cross-section of the human body measured at 1-12 GHz in a reverberant chamber: results of a human volunteer study

NASA Astrophysics Data System (ADS)

Flintoft, I. D.; Robinson, M. P.; Melia, G. C. R.; Marvin, A. C.; Dawson, J. F.

2014-07-01

The electromagnetic absorption cross-section (ACS) averaged over polarization and angle-of-incidence of 60 ungrounded adult subjects was measured at microwave frequencies of 1-12 GHz in a reverberation chamber. Average ACS is important in non-ionizing dosimetry and exposure studies, and is closely related to the whole-body averaged specific absorption rate (WBSAR). The average ACS was measured with a statistical uncertainty of less than 3% and high frequency resolution for individuals with a range of body shapes and sizes allowing the statistical distribution of WBSAR over a real population with individual internal and external morphologies to be determined. The average ACS of all subjects was found to vary from 0.15 to 0.4 m2 for an individual subject it falls with frequency over 1-6 GHz, and then rises slowly over the 6-12 GHz range in which few other studies have been conducted. Average ACS and WBSAR are then used as a surrogate for worst-case ACS/WBSAR, in order to study their variability across a real population compared to literature results from simulations using numerical phantoms with a limited range of anatomies. Correlations with body morphological parameters such as height, mass and waist circumference have been investigated: the strongest correlation is with body surface area (BSA) at all frequencies above 1 GHz, however direct proportionality to BSA is not established until above 5 GHz. When the average ACS is normalized to the BSA, the resulting absorption efficiency shows a negative correlation with the estimated thickness of subcutaneous body fat. Surrogate models and statistical analysis of the measurement data are presented and compared to similar models from the literature. The overall dispersion of measured average WBSAR of the sample of the UK population studied is consistent with the dispersion of simulated worst-case WBSAR across multiple numerical phantom families. The statistical results obtained allow the calibration of human exposure assessments made with particular phantoms to a population with a range of individual morphologies.

Average absorption cross-section of the human body measured at 1-12 GHz in a reverberant chamber: results of a human volunteer study.

PubMed

Flintoft, I D; Robinson, M P; Melia, G C R; Marvin, A C; Dawson, J F

2014-07-07

The electromagnetic absorption cross-section (ACS) averaged over polarization and angle-of-incidence of 60 ungrounded adult subjects was measured at microwave frequencies of 1-12 GHz in a reverberation chamber. Average ACS is important in non-ionizing dosimetry and exposure studies, and is closely related to the whole-body averaged specific absorption rate (WBSAR). The average ACS was measured with a statistical uncertainty of less than 3% and high frequency resolution for individuals with a range of body shapes and sizes allowing the statistical distribution of WBSAR over a real population with individual internal and external morphologies to be determined. The average ACS of all subjects was found to vary from 0.15 to 0.4 m(2); for an individual subject it falls with frequency over 1-6 GHz, and then rises slowly over the 6-12 GHz range in which few other studies have been conducted. Average ACS and WBSAR are then used as a surrogate for worst-case ACS/WBSAR, in order to study their variability across a real population compared to literature results from simulations using numerical phantoms with a limited range of anatomies. Correlations with body morphological parameters such as height, mass and waist circumference have been investigated: the strongest correlation is with body surface area (BSA) at all frequencies above 1 GHz, however direct proportionality to BSA is not established until above 5 GHz. When the average ACS is normalized to the BSA, the resulting absorption efficiency shows a negative correlation with the estimated thickness of subcutaneous body fat. Surrogate models and statistical analysis of the measurement data are presented and compared to similar models from the literature. The overall dispersion of measured average WBSAR of the sample of the UK population studied is consistent with the dispersion of simulated worst-case WBSAR across multiple numerical phantom families. The statistical results obtained allow the calibration of human exposure assessments made with particular phantoms to a population with a range of individual morphologies.

Automatic generation of the index of productive syntax for child language transcripts.

PubMed

Hassanali, Khairun-nisa; Liu, Yang; Iglesias, Aquiles; Solorio, Thamar; Dollaghan, Christine

2014-03-01

The index of productive syntax (IPSyn; Scarborough (Applied Psycholinguistics 11:1-22, 1990) is a measure of syntactic development in child language that has been used in research and clinical settings to investigate the grammatical development of various groups of children. However, IPSyn is mostly calculated manually, which is an extremely laborious process. In this article, we describe the AC-IPSyn system, which automatically calculates the IPSyn score for child language transcripts using natural language processing techniques. Our results show that the AC-IPSyn system performs at levels comparable to scores computed manually. The AC-IPSyn system can be downloaded from www.hlt.utdallas.edu/~nisa/ipsyn.html .

Electrorotation of novel electroactive polymer composites in uniform DC and AC electric fields

NASA Astrophysics Data System (ADS)

Zrinyi, Miklós; Nakano, Masami; Tsujita, Teppei

2012-06-01

Novel electroactive polymer composites have been developed that could spin in uniform DC and AC electric fields. The angular displacement as well as rotation of polymer disks around an axis that is perpendicular to the direction of the applied electric field was studied. It was found that the dynamics of the polymer rotor is very complex. Depending on the strength of the static DC field, three regimes have been observed: no rotation occurs below a critical threshold field intensity, oscillatory motion takes place just above this value and continuous rotation can be observed above the critical threshold field intensity. It was also found that low frequency AC fields could also induce angular deformation.

Fuel magnetization without external field coils (AutoMag)

NASA Astrophysics Data System (ADS)

Slutz, Stephen; Jennings, Christopher; Awe, Thomas; Shipley, Gabe; Lamppa, Derek; McBride, Ryan

2016-10-01

Magnetized Liner Inertial Fusion (MagLIF) has produced fusion-relevant plasma conditions on the Z accelerator where the fuel was magnetized using external field coils. We present a novel concept that does not need external field coils. This concept (AutoMag) magnetizes the fuel during the early part of the drive current by using a composite liner with helical conduction paths separated by insulating material. The drive is designed so the current rises slowly enough to avoid electrical breakdown of the insulators until a sufficiently strong magnetic field is established. Then the current rises more quickly, which causes the insulators to break down allowing the drive current to follow an axial path and implode the liner. Low inductance magnetically insulated power feeds can be used with AutoMag to increase the drive current without interfering with diagnostic access. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Clinical Evaluation of Zero-Echo-Time Attenuation Correction for Brain 18F-FDG PET/MRI: Comparison with Atlas Attenuation Correction.

PubMed

Sekine, Tetsuro; Ter Voert, Edwin E G W; Warnock, Geoffrey; Buck, Alfred; Huellner, Martin; Veit-Haibach, Patrick; Delso, Gaspar

2016-12-01

Accurate attenuation correction (AC) on PET/MR is still challenging. The purpose of this study was to evaluate the clinical feasibility of AC based on fast zero-echo-time (ZTE) MRI by comparing it with the default atlas-based AC on a clinical PET/MR scanner. We recruited 10 patients with malignant diseases not located on the brain. In all patients, a clinically indicated whole-body 18 F-FDG PET/CT scan was acquired. In addition, a head PET/MR scan was obtained voluntarily. For each patient, 2 AC maps were generated from the MR images. One was atlas-AC, derived from T1-weighted liver acquisition with volume acceleration flex images (clinical standard). The other was ZTE-AC, derived from proton-density-weighted ZTE images by applying tissue segmentation and assigning continuous attenuation values to the bone. The AC map generated by PET/CT was used as a silver standard. On the basis of each AC map, PET images were reconstructed from identical raw data on the PET/MR scanner. All PET images were normalized to the SPM5 PET template. After that, these images were qualified visually and quantified in 67 volumes of interest (VOIs; automated anatomic labeling, atlas). Relative differences and absolute relative differences between PET images based on each AC were calculated. 18 F-FDG uptake in all 670 VOIs and generalized merged VOIs were compared using a paired t test. Qualitative analysis shows that ZTE-AC was robust to patient variability. Nevertheless, misclassification of air and bone in mastoid and nasal areas led to the overestimation of PET in the temporal lobe and cerebellum (%diff of ZTE-AC, 2.46% ± 1.19% and 3.31% ± 1.70%, respectively). The |%diff| of all 670 VOIs on ZTE was improved by approximately 25% compared with atlas-AC (ZTE-AC vs. atlas-AC, 1.77% ± 1.41% vs. 2.44% ± 1.63%, P < 0.01). In 2 of 7 generalized VOIs, |%diff| on ZTE-AC was significantly smaller than atlas-AC (ZTE-AC vs. atlas-AC: insula and cingulate, 1.06% ± 0.67% vs. 2.22% ± 1.10%, P < 0.01; central structure, 1.03% ± 0.99% vs. 2.54% ± 1.20%, P < 0.05). The ZTE-AC could provide more accurate AC than clinical atlas-AC by improving the estimation of head-skull attenuation. The misclassification in mastoid and nasal areas must be addressed to prevent the overestimation of PET in regions near the skull base. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Noninvasive remote-controlled release of drug molecules in vitro using magnetic actuation of mechanized nanoparticles.

PubMed

Thomas, Courtney R; Ferris, Daniel P; Lee, Jae-Hyun; Choi, Eunjoo; Cho, Mi Hyeon; Kim, Eun Sook; Stoddart, J Fraser; Shin, Jeon-Soo; Cheon, Jinwoo; Zink, Jeffrey I

2010-08-11

Mesoporous silica nanoparticles are useful nanomaterials that have demonstrated the ability to contain and release cargos with mediation by gatekeepers. Magnetic nanocrystals have the ability to exhibit hyperthermic effects when placed in an oscillating magnetic field. In a system combining these two materials and a thermally sensitive gatekeeper, a unique drug delivery system can be produced. A novel material that incorporates zinc-doped iron oxide nanocrystals within a mesoporous silica framework that has been surface-modified with pseudorotaxanes is described. Upon application of an AC magnetic field, the nanocrystals generate local internal heating, causing the molecular machines to disassemble and allowing the cargos (drugs) to be released. When breast cancer cells (MDA-MB-231) were treated with doxorubicin-loaded particles and exposed to an AC field, cell death occurred. This material promises to be a noninvasive, externally controlled drug delivery system with cancer-killing properties.

A Touch Sensing Technique Using the Effects of Extremely Low Frequency Fields on the Human Body

PubMed Central

Elfekey, Hatem; Bastawrous, Hany Ayad; Okamoto, Shogo

2016-01-01

Touch sensing is a fundamental approach in human-to-machine interfaces, and is currently under widespread use. Many current applications use active touch sensing technologies. Passive touch sensing technologies are, however, more adequate to implement low power or energy harvesting touch sensing interfaces. This paper presents a passive touch sensing technique based on the fact that the human body is affected by the surrounding extremely low frequency (ELF) electromagnetic fields, such as those of AC power lines. These external ELF fields induce electric potentials on the human body—because human tissues exhibit some conductivity at these frequencies—resulting in what is called AC hum. We therefore propose a passive touch sensing system that detects this hum noise when a human touch occurs, thus distinguishing between touch and non-touch events. The effectiveness of the proposed technique is validated by designing and implementing a flexible touch sensing keyboard. PMID:27918416

A Touch Sensing Technique Using the Effects of Extremely Low Frequency Fields on the Human Body.

PubMed

Elfekey, Hatem; Bastawrous, Hany Ayad; Okamoto, Shogo

2016-12-02

Touch sensing is a fundamental approach in human-to-machine interfaces, and is currently under widespread use. Many current applications use active touch sensing technologies. Passive touch sensing technologies are, however, more adequate to implement low power or energy harvesting touch sensing interfaces. This paper presents a passive touch sensing technique based on the fact that the human body is affected by the surrounding extremely low frequency (ELF) electromagnetic fields, such as those of AC power lines. These external ELF fields induce electric potentials on the human body-because human tissues exhibit some conductivity at these frequencies-resulting in what is called AC hum. We therefore propose a passive touch sensing system that detects this hum noise when a human touch occurs, thus distinguishing between touch and non-touch events. The effectiveness of the proposed technique is validated by designing and implementing a flexible touch sensing keyboard.

Individual differences in episodic memory abilities predict successful prospective memory output monitoring.

PubMed

Hunter Ball, B; Pitães, Margarida; Brewer, Gene A

2018-02-07

Output monitoring refers to memory for one's previously completed actions. In the context of prospective memory (PM) (e.g., remembering to take medication), failures of output monitoring can result in repetitions and omissions of planned actions (e.g., over- or under-medication). To be successful in output monitoring paradigms, participants must flexibly control attention to detect PM cues as well as engage controlled retrieval of previous actions whenever a particular cue is encountered. The current study examined individual differences in output monitoring abilities in a group of younger adults differing in attention control (AC) and episodic memory (EM) abilities. The results showed that AC ability uniquely predicted successful cue detection on the first presentation, whereas EM ability uniquely predicted successful output monitoring on the second presentation. The current study highlights the importance of examining external correlates of PM abilities and contributes to the growing body of research on individual differences in PM.

Journal of Special Operations Medicine. Volume 8, Edition 1, Winter 2008

DTIC Science & Technology

2008-01-01

Open, comminuted humerus fracture , treated with external fixation. • Partial transection of the brachial artery. This injury was effectively...would have lost his arm had it not been for the excellent treatment in the field and the rapid evacuation to surgical care. • Three fractured ribs, one of...Soldier with GSW to his left thigh and buttock and left inferior pelvic ac- etabular and rami fractures with communication into the pelvic cavity, with a

Latin America Report

DTIC Science & Technology

1985-04-16

that the cane grows and for pesticides to combat insects. In addition, to calculate the price per ton, it is necessary to take into ac- count the...Production (Cane) 1983-84 Expenditure Cost per ton of cane Materials 53.66 Manure and fertilizer 7.31 Pesticides 10.09 Fuel and lubricants 40.55...then Minister of External Affairs Basil Ince visited Venezuela in March 1984, the deal, was said to be "the major item on the agenda." CSO: 3298

The ACS Survey of Galactic Globular Clusters. VIII. Effects of Environment on Globular Cluster Global Mass Functions

NASA Astrophysics Data System (ADS)

Paust, Nathaniel E. Q.; Reid, I. Neill; Piotto, Giampaolo; Aparicio, Antonio; Anderson, Jay; Sarajedini, Ata; Bedin, Luigi R.; Chaboyer, Brian; Dotter, Aaron; Hempel, Maren; Majewski, Steven; Marín-Franch, A.; Milone, Antonino; Rosenberg, Alfred; Siegel, Michael

2010-02-01

We have used observations obtained as part of the Hubble Space Telescope/ACS Survey of Galactic Globular Clusters to construct global present-day mass functions for 17 globular clusters utilizing multi-mass King models to extrapolate from our observations to the global cluster behavior. The global present-day mass functions for these clusters are well matched by power laws from the turnoff, ≈0.8 M sun, to 0.2-0.3 M sun on the lower main sequence. The slopes of those power-law fits, α, have been correlated with an extensive set of intrinsic and extrinsic cluster properties to investigate which parameters may influence the form of the present-day mass function. We do not confirm previous suggestions of correlations between α and either metallicity or Galactic location. However, we do find a strong statistical correlation with the related parameters central surface brightness, μ V , and inferred central density, ρ0. The correlation is such that clusters with denser cores (stronger binding energy) tend to have steeper mass functions (a higher proportion of low-mass stars), suggesting that dynamical evolution due to external interactions may have played a key role in determining α. Thus, the present-day mass function may owe more to nurture than to nature. Detailed modeling of external dynamical effects is therefore a requisite for determining the initial mass function for Galactic globular clusters.

Paper pulp-based adsorbents for the removal of pharmaceuticals from wastewater: A novel approach towards diversification.

PubMed

Oliveira, Gonçalo; Calisto, Vânia; Santos, Sérgio M; Otero, Marta; Esteves, Valdemar I

2018-08-01

In this work, two pulps, bleached (BP) and raw pulp (RP), derived from the paper production process, were used as precursors of non-activated and activated carbons (ACs). In the case of non-ACs, the production involved either pyrolysis or pyrolysis followed by acid washing. For ACs production, the pulps were impregnated with K 2 CO 3 or H 3 PO 4 , and then pyrolysed and acid washed. After production, the materials were physically and chemically characterized. Then, batch adsorption tests on the removal of two pharmaceuticals (the anti-epileptic carbamazepine (CBZ) and the antibiotic sulfamethoxazole (SMX)) from ultra-pure water and from Waste Water Treatment Plant (WWTP) effluents were performed. In ultra-pure water, non-ACs were not able to adsorb CBZ or SMX while ACs showed good adsorption capacities. In WWTP effluents, although ACs satisfactorily adsorbed CBZ and SMX, they showed lower adsorption capacities for the latter. Tests with WWTP effluents revealed that the best adsorption capacities were achieved by carbons produced from BP and activated with H 3 PO 4 : 92±19mgg -1 for CBZ and 13.0±0.6mgg -1 for SMX. These results indicate the potential of paper pulps as precursors for ACs that can be applied in wastewater treatment. Copyright © 2018 Elsevier B.V. All rights reserved.

Arthroscopically Assisted Reconstruction of Acute Acromioclavicular Joint Dislocations: Anatomic AC Ligament Reconstruction With Protective Internal Bracing—The “AC-RecoBridge” Technique

PubMed Central

Izadpanah, Kaywan; Jaeger, Martin; Ogon, Peter; Südkamp, Norbert P.; Maier, Dirk

2015-01-01

An arthroscopically assisted technique for the treatment of acute acromioclavicular joint dislocations is presented. This pathology-based procedure aims to achieve anatomic healing of both the acromioclavicular ligament complex (ACLC) and the coracoclavicular ligaments. First, the acromioclavicular joint is reduced anatomically under macroscopic and radiologic control and temporarily transfixed with a K-wire. A single-channel technique using 2 suture tapes provides secure coracoclavicular stabilization. The key step of the procedure consists of the anatomic repair of the ACLC (“AC-Reco”). Basically, we have observed 4 patterns of injury: clavicular-sided, acromial-sided, oblique, and midportion tears. Direct and/or transosseous ACLC repair is performed accordingly. Then, an X-configured acromioclavicular suture tape cerclage (“AC-Bridge”) is applied under arthroscopic assistance to limit horizontal clavicular translation to a physiological extent. The AC-Bridge follows the principle of internal bracing and protects healing of the ACLC repair. The AC-Bridge is tightened on top of the repair, creating an additional suture-bridge effect and promoting anatomic ACLC healing. We refer to this combined technique of anatomic ACLC repair and protective internal bracing as the “AC-RecoBridge.” A detailed stepwise description of the surgical technique, including indications, technical pearls and pitfalls, and potential complications, is given. PMID:26052493

Biodegradation studies of N4-acetylsulfapyridine and N4-acetylsulfamethazine in environmental water by applying mass spectrometry techniques.

PubMed

García-Galán, María Jesús; Frömel, Tobias; Müller, Jutta; Peschka, Manuela; Knepper, Thomas; Díaz-Cruz, Silvia; Barceló, Damiá

2012-03-01

This work evaluates the biodegradation of N(4)-acetylsulfapyridine (AcSPY) and N(4)-acetylsulfamethazine (AcSMZ), metabolites of two of the most commonly used sulfonamides (SAs) in human and veterinary medicine, respectively. Aerobic transformation in effluent wastewater was simulated using aerated fixed-bed bioreactors. No visible changes in concentration were observed in the AcSMZ reactor after 90 days, whereas AcSPY was fully degraded after 32 days of experiment. It was also demonstrated that AcSPY transformed back to its parent compound sulfapyridine (SPY). The environmental presence of these two metabolites in wastewater effluent had been previously investigated and confirmed, together with three more SA acetylated metabolites and their corresponding parent compounds, in 18 different wastewater treatment plants in Hesse (Germany). Sulfamethoxazole (SMX) and SPY were the two SAs detected most frequently (90% and 89% of the samples, respectively) and in the highest concentrations (682 ng L(-1) for SMX and 532 ng L(-1) for SPY). To conclude, hazard quotients were calculated whenever toxicity data were available. None of the SAs studied posed an environmental risk.

Analysis of Electrokinetic Mixing Using AC Electric Field and Patchwise Surface Heterogeneities

NASA Astrophysics Data System (ADS)

Luo, Win-Jet; Yarn, Kao-Feng; Hsu, Shou-Ping

2007-04-01

In this paper, the authors investigate the use of an applied AC electric field and microchannel surface heterogeneities to carry out the microfluidic mixing of two-dimensional, time-dependent electroosmotic flows. The time-dependent flow fields within the microchannel are simulated using the backwards-Euler time-stepping numerical method. The mixing efficiencies obtained in microchannels with two different patchwise surface heterogeneity patterns are investigated. In general, the results show that the application of an AC electric field significantly reduces the required mixing length compared with the use of a DC electric field. Furthermore, the presence of oppositely charged surface heterogeneities on the microchannel walls results in the formation of localized flow circulation regions within the bulk flow. These circulation regions grow and decay periodically in accordance with the periodic variation of the AC electric field intensity and provide an effective means of enhancing species mixing in the microchannel. Consequently, the use of an AC electric field together with patchwise surface heterogeneities permits a significant reduction in both the mixing channel length and the retention time required to attain a homogeneous solution.

AC loss modelling and experiment of two types of low-inductance solenoidal coils

NASA Astrophysics Data System (ADS)

Liang, Fei; Yuan, Weijia; Zhang, Min; Zhang, Zhenyu; Li, Jianwei; Venuturumilli, Sriharsha; Patel, Jay

2016-11-01

Low-inductance solenoidal coils, which usually refer to the nonintersecting type and the braid type, have already been employed to build superconducting fault current limiters because of their fast recovery and low inductance characteristics. However, despite their usage there is still no systematical simulation work concerning the AC loss characteristics of the coils built with 2G high temperature superconducting tapes perhaps because of their complicated structure. In this paper, a new method is proposed to simulate both types of coils with 2D axisymmetric models solved by H formulation. Following the simulation work, AC losses of both types of low inductance solenoidal coils are compared numerically and experimentally, which verify that the model works well in simulating non-inductive coils. Finally, simulation works show that pitch has significant impact to AC loss of both types of coils and the inter-layer separation has different impact to the AC loss of braid type of coil in case of different applied currents. The model provides an effective tool for the design optimisation of SFCLs built with non-inductive solenoidal coils.

Code C# for chaos analysis of relativistic many-body systems

NASA Astrophysics Data System (ADS)

Grossu, I. V.; Besliu, C.; Jipa, Al.; Bordeianu, C. C.; Felea, D.; Stan, E.; Esanu, T.

2010-08-01

This work presents a new Microsoft Visual C# .NET code library, conceived as a general object oriented solution for chaos analysis of three-dimensional, relativistic many-body systems. In this context, we implemented the Lyapunov exponent and the “fragmentation level” (defined using the graph theory and the Shannon entropy). Inspired by existing studies on billiard nuclear models and clusters of galaxies, we tried to apply the virial theorem for a simplified many-body system composed by nucleons. A possible application of the “virial coefficient” to the stability analysis of chaotic systems is also discussed. Catalogue identifier: AEGH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEGH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 30 053 No. of bytes in distributed program, including test data, etc.: 801 258 Distribution format: tar.gz Programming language: Visual C# .NET 2005 Computer: PC Operating system: .Net Framework 2.0 running on MS Windows Has the code been vectorized or parallelized?: Each many-body system is simulated on a separate execution thread RAM: 128 Megabytes Classification: 6.2, 6.5 External routines: .Net Framework 2.0 Library Nature of problem: Chaos analysis of three-dimensional, relativistic many-body systems. Solution method: Second order Runge-Kutta algorithm for simulating relativistic many-body systems. Object oriented solution, easy to reuse, extend and customize, in any development environment which accepts .Net assemblies or COM components. Implementation of: Lyapunov exponent, “fragmentation level”, “average system radius”, “virial coefficient”, and energy conservation precision test. Additional comments: Easy copy/paste based deployment method. Running time: Quadratic complexity.

Preexisting severe cervical spinal cord compression is a significant risk factor for severe paralysis development in patients with traumatic cervical spinal cord injury without bone injury: a retrospective cohort study.

PubMed

Oichi, Takeshi; Oshima, Yasushi; Okazaki, Rentaro; Azuma, Seiichi

2016-01-01

The objective of this study is to investigate whether preexisting severe cervical spinal cord compression affects the severity of paralysis once patients develop traumatic cervical spinal cord injury (CSCI) without bone injury. We retrospectively investigated 122 consecutive patients with traumatic CSCI without bone injury. The severity of paralysis on admission was assessed by the American Spinal Injury Association impairment scale (AIS). The degree of preexisting cervical spinal cord compression was evaluated by the maximum spinal cord compression (MSCC) and was divided into three categories: minor compression (MSCC ≤ 20 %), moderate compression (20 % < MSCC ≤ 40 %), and severe compression (40 % < MSCC). We investigated soft-tissue damage on magnetic resonance imaging to estimate the external force applied. Other potential risk factors, including age, sex, fused vertebra, and ossification of longitudinal ligament, were also reviewed. A multivariate logistic regression analysis was performed to investigate the risk factors for developing severe paralysis (AIS A-C) on admission. Our study included 103 males and 19 females with mean age of 65 years. Sixty-one patients showed severe paralysis (AIS A-C) on admission. The average MSCC was 22 %. Moderate compression was observed in 41, and severe in 20. Soft-tissue damage was observed in 91. A multivariate analysis showed that severe cervical spinal cord compression significantly affected the severity of paralysis at the time of injury, whereas both mild and moderate compression did not affect it. Soft-tissue damage was also significantly associated with severe paralysis on admission. Preexisting severe cervical cord compression is an independent risk factor for severe paralysis once patients develop traumatic CSCI without bone injury.

Synthetic polymers blend used in the production of high activated carbon for pesticides removals from liquid phase.

PubMed

Belo, Cristóvão Ramiro; Cansado, Isabel Pestana da Paixão; Mourão, Paulo Alexandre Mira

2017-02-01

For the activated carbon (AC) production, we used the most common industrial and consumer solid waste, namely polyethyleneterephthalate (PET), alone or blended with other synthetic polymer such polyacrylonitrile (PAN). By mixing PET, with PAN, an improvement in the yield of the AC production was found and the basic character and some textural and chemical properties were enhanced. The PET-PAN mixture was subjected to carbonisation, with a pyrolysis yield of 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. The AC revealed a high surface area (1400, 1230 and 1117 m 2  g -1 ) and pore volume (0.46, 0.56 and 0.50 cm 3  g -1 ), respectively, for PET, PAN and PET-PAN precursors. Selected ACs were successfully tested for 4-chloro-2-methylphenoxyacetic acid (MCPA) and diuron removal from the liquid phase, showing a higher adsorption capacity (1.7 and 1.2 mmol g -1 , respectively, for MCPA and diuron) and good fits with the Langmuir (PET) and Freundlich equation (PAN and PET-PAN blend). With MCPA, the controlling factor to the adsorption capacity was the porous volume and the average pore size. Concerning diuron, the adsorption was controlled essentially by the external diffusion. A remarkable result is the use of different synthetic polymers wastes, as precursors for the production of carbon materials, with high potential application on the pesticides removals from the liquid phase.

MAGNETOMETER

DOEpatents

Leavitt, M.A.

1958-11-18

A magnetometer ls described, partlcularly to a device which accurately indicates the polarity and intensity of a magnetlc field. The main feature of the invention is a unique probe construction in combinatlon wlth a magnetic fleld detector system. The probe comprises two coils connected in series opposition for energization with an a-c voltage. The voltage lnduced in a third coll on the probe, a pick-up coil, is distorted by the presence of an external field to produce even harmonic voltages. A controlled d-c current is passed through the energized coils to counter the dlstortlon and reduce tbe even harmonic content to a null. When the null point is reached, the d-c current is a measure of the external magnetic field strength, and the phase of the pickup coil voltage indicates tbe field polarlty.

Vehicle drive module having improved terminal design

DOEpatents

Beihoff, Bruce C.; Radosevich, Lawrence D.; Phillips, Mark G.; Kehl, Dennis L.; Kaishian, Steven C.; Kannenberg, Daniel G.

2006-04-25

A terminal structure for vehicle drive power electronics circuits reduces the need for a DC bus and thereby the incidence of parasitic inductance. The structure is secured to a support that may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as by direct contact between the terminal assembly and AC and DC circuit components. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Power converter having improved terminal structure

DOEpatents

Radosevich, Lawrence D.; Kannenberg, Daniel G.; Phillips, Mark G.; Kaishian, Steven C.

2007-03-06

A terminal structure for power electronics circuits reduces the need for a DC bus and thereby the incidence of parasitic inductance. The structure is secured to a support that may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support may form a shield from both external EMI/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as by direct contact between the terminal assembly and AC and DC circuit components. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

Five-year Effects of Chlorhexidine on the In Vitro Durability of Resin/Dentin Interfaces.

PubMed

Loguercio, Alessandro D; Hass, Viviane; Gutierrez, Mario Felipe; Luque-Martinez, Issis Virginia; Szezs, Anna; Stanislawczuk, Rodrigo; Bandeca, Matheus Coelho; Reis, Alessandra

2016-01-01

To evaluate the effect of an acid containing 2% chlorhexidine (Ac/CHX) or a 2% CHX aqueous solution (Aq/CHX) on the immediate and 5-year bonding properties of resin/dentin interfaces produced by two adhesives. The presence of CHX in these interfaces was also evaluated under micro-Raman spectroscopy. Forty-two molars were ground to expose a flat dentin surface. In the control group, the surfaces were etched with conventional phosphoric acid, and Prime&Bond NT (PB) and Adper Single Bond 2 (SB) were applied. In Ac/CHX, an acid containing 2% CHX was applied after adhesive application. In the Aq/CHX group, an aqueous solution of 2% CHX was applied for 60 s after etching. After placing the restoration, specimens were prepared and tested using the microtensile bond strength test (μTBS, 0.5 mm/min) immediately or after 5 years. For nanoleakage (NL), specimens at each period were immersed in silver nitrate solution and examined by EDX-SEM. In addition, specimens at each period underwent examination for CHX using micro-Raman spectroscopy. Data were submitted to appropriate statistical analysis (a=0.05). After 5 years, NL was more pronounced in the control than in the Ac/CHX or Aq/CHX (p<0.001). Significant reductions in the μTBS were observed for all groups; however, they were more pronounced for the control (p<0.001). CHX was still present in the hybrid layers Ac/CHX or Aq/CHX groups after 5 years. The use of a 2% chlorhexidine-containing acid or the application of an aqueous CHX primer may increase the long-term stability of resin/dentin interfaces.

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABAA Inhibition: A tACS-TMS Study

PubMed Central

van Ede, Freek

2017-01-01

Beta and gamma oscillations are the dominant oscillatory activity in the human motor cortex (M1). However, their physiological basis and precise functional significance remain poorly understood. Here, we used transcranial magnetic stimulation (TMS) to examine the physiological basis and behavioral relevance of driving beta and gamma oscillatory activity in the human M1 using transcranial alternating current stimulation (tACS). tACS was applied using a sham-controlled crossover design at individualized intensity for 20 min and TMS was performed at rest (before, during, and after tACS) and during movement preparation (before and after tACS). We demonstrated that driving gamma frequency oscillations using tACS led to a significant, duration-dependent decrease in local resting-state GABAA inhibition, as quantified by short interval intracortical inhibition. The magnitude of this effect was positively correlated with the magnitude of GABAA decrease during movement preparation, when gamma activity in motor circuitry is known to increase. In addition, gamma tACS-induced change in GABAA inhibition was closely related to performance in a motor learning task such that subjects who demonstrated a greater increase in GABAA inhibition also showed faster short-term learning. The findings presented here contribute to our understanding of the neurophysiological basis of motor rhythms and suggest that tACS may have similar physiological effects to endogenously driven local oscillatory activity. Moreover, the ability to modulate local interneuronal circuits by tACS in a behaviorally relevant manner provides a basis for tACS as a putative therapeutic intervention. SIGNIFICANCE STATEMENT Gamma oscillations have a vital role in motor control. Using a combined tACS-TMS approach, we demonstrate that driving gamma frequency oscillations modulates GABAA inhibition in the human motor cortex. Moreover, there is a clear relationship between the change in magnitude of GABAA inhibition induced by tACS and the magnitude of GABAA inhibition observed during task-related synchronization of oscillations in inhibitory interneuronal circuits, supporting the hypothesis that tACS engages endogenous oscillatory circuits. We also show that an individual's physiological response to tACS is closely related to their ability to learn a motor task. These findings contribute to our understanding of the neurophysiological basis of motor rhythms and their behavioral relevance and offer the possibility of developing tACS as a therapeutic tool. PMID:28348136

A Novel Approach to Apply Gait Synchronized External Forces on the Pelvis using A-TPAD to Reduce Walking Effort

PubMed Central

Vashista, Vineet; Khan, Moiz; Agrawal, Sunil K.

2017-01-01

In this paper, we develop an intervention to apply external gait synchronized forces on the pelvis to reduce the user’s effort during walking. A cable-driven robot was used to apply the external forces and an adaptive frequency oscillator scheme was developed to adapt the timing of force actuation to the gait frequency during walking. The external forces were directed in the sagittal plane to assist the trailing leg during the forward propulsion and vertical deceleration of the pelvis during the gait cycle. A pilot experiment with five healthy subjects was conducted. The results showed that the subjects applied lower ground reaction forces in the vertical and anterior-posterior directions during the late stance phase. In summary, the current work provides a novel approach to study the role of external pelvic forces in altering the walking effort. These studies can provide better understanding for designing exoskeletons and prosthetic devices to reduce the overall walking effort. PMID:29623294

Investigation of flux penetration in YBa 2Cu 3O 7-δ filaments

NASA Astrophysics Data System (ADS)

Devos, P.; Buekenhoudt, A.; D'Anna, G.; André, M.-O.; Indenbom, M. V.; Benoit, W.; De Batist, R.; Cornelis, J.

1994-12-01

ac Susceptibility measurements using a low frequency torsion pendulum and an ac susceptometer were conducted on YBa 2Cu 3O 7-δ filaments in low magnetic dc fields (≤1T). Different dissipation peaks are observed, dependent on the temperature and the applied amplitude. The peak at low temperatures, which is of intergranular nature is studied in detail. The penetration follows the Bean model and the intergranular creep is observed.

Electric-Field Instrument With Ac-Biased Corona Point

NASA Technical Reports Server (NTRS)

Markson, R.; Anderson, B.; Govaert, J.

1993-01-01

Measurements indicative of incipient lightning yield additional information. New instrument gives reliable readings. High-voltage ac bias applied to needle point through high-resistance capacitance network provides corona discharge at all times, enabling more-slowly-varying component of electrostatic potential of needle to come to equilibrium with surrounding air. High resistance of high-voltage coupling makes instrument insensitive to wind. Improved corona-point instrument expected to yield additional information assisting in safety-oriented forecasting of lighting.

Effect of preharvest understory treatment and group opening size on four-year survival of advance reproduction in the Boston Mountains of Arkansas

Treesearch

Martin A. Spetich; David L. Graney

2003-01-01

The purpose of this study was to examine survival of regeneration in small openings. Six forest stands were located in 1990 and three understory treatments were applied to each in early 1991. In each stand, six sizes of openings were created in 1992 ranging in size from 0.025 ac to 0.50 ac. Understory treatments consisted of: 1) no control of competing...

Effect of preharvest understory treatment and group opening size on four-year survival of advance reproduction in the Boston Mountains of Arkansas

Treesearch

Martin A. Spetich; David L. Graney

2003-01-01

The purpose of this study was to examine survival of regeneration in small openings. Six forest stands were located in 1990 and three understory treatments were applied to each in early 1991. In each stand, six sizes of openings were created in 1992 ranging in size from 0.025 ac to 0.50 ac. Understory treatments consisted of: 1) no control of competing regeneration, 2...

Electric-field control of a hydrogenic donor's spin in a semiconductor

NASA Astrophysics Data System (ADS)

de, Amrit; Pryor, Craig E.; Flatté, Michael E.

2009-03-01

The orbital wave function of an electron bound to a single donor in a semiconductor can be modulated by an applied AC electric field, which affects the electron spin dynamics via the spin-orbit interaction. Numerical calculations of the spin dynamics of a single hydrogenic donor (Si) using a real-space multi-band k.p formalism show that in addition to breaking the high symmetry of the hydrogenic donor state, the g-tensor has a strong nonlinear dependence on the applied fields. By explicitly integrating the time dependent Schr"odinger equation it is seen that Rabi oscillations can be obtained for electric fields modulated at sub-harmonics of the Larmor frequency. The Rabi frequencies obtained from sub-harmonic modulation depend on the magnitudes of the AC and DC components of the electric field. For a purely AC field, the highest Rabi frequency is obtained when E is driven at the 2nd sub-harmonic of the Larmor frequency. Apart from suggesting ways to measure g-tensor anisotropies and nonlinearities, these results also suggest the possibility of direct frequency domain measurements of Rabi frequencies.

Measurements of Induced-Charge Electroosmotic Flow Around a Metallic Rod

NASA Astrophysics Data System (ADS)

Beskok, Ali; Canpolat, Cetin

2012-11-01

A cylindrical gold-coated stainless steel rod was positioned at the center of a straight microchannel connecting two fluid reservoirs on either end. The microchannel was filled with 1 mM KCl containing 0.5 micron diameter carboxylate-modified spherical particles. Induced-charge electro-osmotic (ICEO) flow occurred around the metallic rod under a sinusoidal AC electric field applied using two platinum electrodes. The ICEO flows around the metallic rod were measured using micro particle image velocimetry (micro-PIV) technique as functions of the AC electric field strength and frequency. The present study provides experimental data about ICEO flow in the weakly nonlinear limit of thin double layers, in which, the charging dynamics of the double layer cannot be presented analytically. Flow around the rod is quadrupolar, driving liquid towards the rod along the electric field and forcing it away from the rod in the direction perpendicular to the imposed electric field. The measured ICEO flow velocity is proportional to the square of the electric field strength, and depends on the applied AC frequency.

Study of transport phenomena in laser-driven, non- equilibrium plasmas in the presence of external magnetic fields

NASA Astrophysics Data System (ADS)

Kemp, G. Elijah; Mariscal, D. A.; Williams, G. J.; Blue, B. E.; Colvin, J. D.; Fears, T. M.; Kerr, S. M.; May, M. J.; Moody, J. D.; Strozzi, D. J.; Lefevre, H. J.; Klein, S. R.; Kuranz, C. C.; Manuel, M. J.-E.; Gautier, D. C.; Montgomery, D. S.

2017-10-01

We present experimental and simulation results from a study of thermal transport inhibition in laser-driven, mid-Z, non-equilibrium plasmas in the presence external magnetic fields. The experiments were performed at the Jupiter Laser Facility at LLNL, where x-ray spectroscopy, proton radiography, and Brillouin backscatter data were simultaneously acquired from sub-critical-density, Ti-doped silica aerogel foams driven by a 2 ω laser at 5 ×1014 W /cm2 . External B-field strengths up to 20 T (aligned antiparallel to the laser propagation axis) were provided by a capacitor-bank-driven Helmholtz coil. Pre-shot simulations with Hydra, a radiation-magnetohydrodyanmics code, showed increasing electron plasma temperature with increasing B-field strength - the result of thermal transport inhibition perpendicular to the B-field. The influence of this thermal transport inhibition on the experimental observables as a function of external field strength and target density will be shown and compared with simulations. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 and funded by LDRD project 17-ERD-027.

Assessing summertime urban air conditioning consumption in a semiarid environment

NASA Astrophysics Data System (ADS)

Salamanca, F.; Georgescu, M.; Mahalov, A.; Moustaoui, M.; Wang, M.; Svoma, B. M.

2013-09-01

Evaluation of built environment energy demand is necessary in light of global projections of urban expansion. Of particular concern are rapidly expanding urban areas in environments where consumption requirements for cooling are excessive. Here, we simulate urban air conditioning (AC) electric consumption for several extreme heat events during summertime over a semiarid metropolitan area with the Weather Research and Forecasting (WRF) model coupled to a multilayer building energy scheme. Observed total load values obtained from an electric utility company were split into two parts, one linked to meteorology (i.e., AC consumption) which was compared to WRF simulations, and another to human behavior. WRF-simulated non-dimensional AC consumption profiles compared favorably to diurnal observations in terms of both amplitude and timing. The hourly ratio of AC to total electricity consumption accounted for ˜53% of diurnally averaged total electric demand, ranging from ˜35% during early morning to ˜65% during evening hours. Our work highlights the importance of modeling AC electricity consumption and its role for the sustainable planning of future urban energy needs. Finally, the methodology presented in this article establishes a new energy consumption-modeling framework that can be applied to any urban environment where the use of AC systems is prevalent.

The Feasibility of Applying AC Driven Low-Temperature Plasma for Multi-Cycle Detonation Initiation

NASA Astrophysics Data System (ADS)

Zheng, Dianfeng

2016-11-01

Ignition is a key system in pulse detonation engines (PDE). As advanced ignition methods, nanosecond pulse discharge low-temperature plasma ignition is used in some combustion systems, and continuous alternating current (AC) driven low-temperature plasma using dielectric barrier discharge (DBD) is used for the combustion assistant. However, continuous AC driven plasmas cannot be used for ignition in pulse detonation engines. In this paper, experimental and numerical studies of pneumatic valve PDE using an AC driven low-temperature plasma igniter were described. The pneumatic valve was jointly designed with the low-temperature plasma igniter, and the numerical simulation of the cold-state flow field in the pneumatic valve showed that a complex flow in the discharge area, along with low speed, was beneficial for successful ignition. In the experiments ethylene was used as the fuel and air as oxidizing agent, ignition by an AC driven low-temperature plasma achieved multi-cycle intermittent detonation combustion on a PDE, the working frequency of the PDE reached 15 Hz and the peak pressure of the detonation wave was approximately 2.0 MPa. The experimental verifications of the feasibility in PDE ignition expanded the application field of AC driven low-temperature plasma. supported by National Natural Science Foundation of China (No. 51176001)

Effect of fee-for-service air-conditioning management in balancing thermal comfort and energy usage.

PubMed

Chen, Chen-Peng; Hwang, Ruey-Lung; Shih, Wen-Mei

2014-11-01

Balancing thermal comfort with the requirement of energy conservation presents a challenge in hot and humid areas where air-conditioning (AC) is frequently used in cooling indoor air. A field survey was conducted in Taiwan to demonstrate the adaptive behaviors of occupants in relation to the use of fans and AC in a school building employing mixed-mode ventilation where AC use was managed under a fee-for-service mechanism. The patterns of using windows, fans, and AC as well as the perceptions of students toward the thermal environment were examined. The results of thermal perception evaluation in relation to the indoor thermal conditions were compared to the levels of thermal comfort predicted by the adaptive models described in the American Society of Heating, Refrigerating, and Air-Conditioning Engineers Standard 55 and EN 15251 and to that of a local model for evaluating thermal adaption in naturally ventilated buildings. A thermal comfort-driven adaptive behavior model was established to illustrate the probability of fans/AC use at specific temperature and compared to the temperature threshold approach to illustrate the potential energy saving the fee-for-service mechanism provided. The findings of this study may be applied as a reference for regulating the operation of AC in school buildings of subtropical regions.

9 CFR 307.7 - Safety requirements for electrical stimulating (EST) equipment.

Code of Federal Regulations, 2012 CFR

2012-01-01

... requirements for electrical stimulating (EST) equipment. (a) General. Electrical stimulating (EST) equipment is... of facilitating blood removal. These provisions do not apply to electrical equipment used to stun and... generate pulsed DC or AC voltage for stimulation and is separate from the equipment used to apply the...

9 CFR 307.7 - Safety requirements for electrical stimulating (EST) equipment.

Code of Federal Regulations, 2014 CFR

2014-01-01

... requirements for electrical stimulating (EST) equipment. (a) General. Electrical stimulating (EST) equipment is... of facilitating blood removal. These provisions do not apply to electrical equipment used to stun and... generate pulsed DC or AC voltage for stimulation and is separate from the equipment used to apply the...

Using nonlinear ac electrokinetics vortex flow to enhance catalytic activities of sol-gel encapsulated trypsin in microfluidic devices

PubMed Central

Wang, Shau-Chun; Chen, Hsiao-Ping; Lai, Yi-Wen; Chau, Lai-Kwan; Chuang, Yu-Chun; Chen, Yi-Jie

2007-01-01

A novel microstirring strategy is applied to accelerate the digestion rate of the substrate Nα-benzoyl-L-arginine-4-nitroanilide (L-BAPA) catalyzed by sol-gel encapsulated trypsin. We use an ac nonlinear electrokinetic vortex flow to stir the solution in a microfluidic reaction chamber to reduce the diffusion length between the immobilized enzyme and substrate in the solution. High-intensity nonlinear electroosmotic microvortices, with angular speeds in excess of 1 cm∕s, are generated around a small (∼1.2 mm) conductive ion exchange granule when ac electric fields (133 V∕cm) are applied across a miniature chamber smaller than 10 μl. Coupling between these microvortices and the on-and-off electrophoretic motion of the granule in low frequency (0.1 Hz) ac fields produces chaotic stream lines to stir substrate molecules sufficiently. We demonstrate that, within a 5-min digestion period, the catalytic reaction rate of immobilized trypsin increases almost 30-fold with adequate reproducibility (15%) due to sufficient stirring action through the introduction of the nonlinear electrokinetic vortices. In contrast, low-frequency ac electroosmotic flow without the granule, provides limited stirring action and increases the reaction rate approximately ninefold with barely acceptable reproducibility (30%). Dye molecules are used to characterize the increases in solute diffusivity in the reaction reservoir in which sol-gel particles are placed, with and without the presence of granule, and compared with the static case. The solute diffusivity enhancement data show respective increases of ∼30 and ∼8 times, with and without the presence of granule. These numbers are consistent with the ratios of the enhanced reaction rate. PMID:19693360

Dynamic microparticle manipulation with an electroosmotic flow gradient in low-frequency alternating current dielectrophoresis.

PubMed

Gencoglu, Aytug; Olney, David; LaLonde, Alexandra; Koppula, Karuna S; Lapizco-Encinas, Blanca H

2014-02-01

In this study, the potential of low-frequency AC insulator-based DEP (iDEP) was explored for the separation of polystyrene microparticles and yeast cells. An EOF gradient was generated by employing an asymmetrical, 20 Hz AC electrical signal in an iDEP device consisting of a microchannel with diamond-shaped insulating posts. Two types of samples were analyzed, the first sample contained three types of polystyrene particles with different diameters (0.5, 1.0, and 2.0 μm) and the second sample contained two types of polystyrene particles (1.0 and 2 μm) and yeast cells (6.3 μm). This particular scheme uses a tapered AC signal that allows for all particles to be trapped and concentrated at the insulating post array, as the signal becomes asymmetrical (more positive), particles are selectively released. The smallest particles in each sample were released first, since they require greater dielectrophoretic forces to remain trapped. The largest particles in each sample were released last, when the applied signal became cyclical. A dielectropherogram, which is analogous to a chromatogram, was obtained for each sample, demonstrating successful separation of the particles by showing "peaks" of the released particles. These separations were achieved at lower applied potentials than those reported in previous studies that used solely direct current electrical voltages. Additionally, mathematical modeling with COMSOL Multiphysics was carried out to estimate the magnitude of the dielectrophoretic and EOF forces acting on the particles considering the low-frequency, asymmetrical AC signal used in the experiments. The results demonstrated the potential of low-frequency AC-iDEP systems for handling and separating complex mixtures of microparticles and biological cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using nonlinear ac electrokinetics vortex flow to enhance catalytic activities of sol-gel encapsulated trypsin in microfluidic devices.

PubMed

Wang, Shau-Chun; Chen, Hsiao-Ping; Lai, Yi-Wen; Chau, Lai-Kwan; Chuang, Yu-Chun; Chen, Yi-Jie

2007-09-04

A novel microstirring strategy is applied to accelerate the digestion rate of the substrate N(alpha)-benzoyl-L-arginine-4-nitroanilide (L-BAPA) catalyzed by sol-gel encapsulated trypsin. We use an ac nonlinear electrokinetic vortex flow to stir the solution in a microfluidic reaction chamber to reduce the diffusion length between the immobilized enzyme and substrate in the solution. High-intensity nonlinear electroosmotic microvortices, with angular speeds in excess of 1 cms, are generated around a small ( approximately 1.2 mm) conductive ion exchange granule when ac electric fields (133 Vcm) are applied across a miniature chamber smaller than 10 mul. Coupling between these microvortices and the on-and-off electrophoretic motion of the granule in low frequency (0.1 Hz) ac fields produces chaotic stream lines to stir substrate molecules sufficiently. We demonstrate that, within a 5-min digestion period, the catalytic reaction rate of immobilized trypsin increases almost 30-fold with adequate reproducibility (15%) due to sufficient stirring action through the introduction of the nonlinear electrokinetic vortices. In contrast, low-frequency ac electroosmotic flow without the granule, provides limited stirring action and increases the reaction rate approximately ninefold with barely acceptable reproducibility (30%). Dye molecules are used to characterize the increases in solute diffusivity in the reaction reservoir in which sol-gel particles are placed, with and without the presence of granule, and compared with the static case. The solute diffusivity enhancement data show respective increases of approximately 30 and approximately 8 times, with and without the presence of granule. These numbers are consistent with the ratios of the enhanced reaction rate.

AC electroosmotic micromixer for chemical processing in a microchannel.

PubMed

Sasaki, Naoki; Kitamori, Takehiko; Kim, Haeng-Boo

2006-04-01

A rapid micromixer of fluids in a microchannel is presented. The mixer uses AC electroosmotic flow, which is induced by applying an AC voltage to a pair of coplanar meandering electrodes configured in parallel to the channel. To demonstrate performance of the mixer, dilution experiments were conducted using a dye solution in a channel of 120 microm width. Rapid mixing was observed for flow velocity up to 12 mm s(-1). The mixing time was 0.18 s, which was 20-fold faster than that of diffusional mixing without an additional mixing mechanism. Compared with the performance of reported micromixers, the present mixer worked with a shorter mixing length, particularly at low Peclet numbers (Pe < 2 x 10(3)).

USAF 1990 Research Initiation Program. Volume 3

DTIC Science & Technology

1992-06-25

the reinforcement outward, both on the entrance and exit sides. The reinforcement was bent outward like a membrane under internal prressure. This led...potential of a neuron. C: cell capacitance. R: membrane resistance. w: synaptic weight. h(x): sigmoidal function describing the firing rate. y: external...Proof: The uncertain closed loop plant may be written as x(t)=(A+AA)x(t)+(Ao+ AAo )x(t-T) (B+AB)F(C AC)x(t) =(A+BFC)x(t)+(AA+ABFC+BFAC+ABFAC)x(t)+(Ao+Ao)X(t

49 CFR 192.461 - External corrosion control: Protective coating.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 3 2011-10-01 2011-10-01 false External corrosion control: Protective coating... for Corrosion Control § 192.461 External corrosion control: Protective coating. (a) Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion control...

49 CFR 192.461 - External corrosion control: Protective coating.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 3 2010-10-01 2010-10-01 false External corrosion control: Protective coating... for Corrosion Control § 192.461 External corrosion control: Protective coating. (a) Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion control...

Open external circuit for microbial fuel cell sensor to monitor the nitrate in aquatic environment.

PubMed

Wang, Donglin; Liang, Peng; Jiang, Yong; Liu, Panpan; Miao, Bo; Hao, Wen; Huang, Xia

2018-07-15

This study employed an open external circuit, rather than a closed circuit applied in previous studies, to operate an microbial fuel cell (MFC) sensor for real-time nitrate monitoring, and achieved surprisingly greater sensitivity (4.42 ± 0.3-6.66 ± 0.4 mV/(mg/L)) when the nitrate was at a concentration of 10-40 mg/L, compared to that of the MFC sensor with a closed circuit (0.8 ± 0.05-1.6 ± 0.1 mV/(mg/L)). The MFC sensor operated in open circuit (O-MFC sensor) delivered much more stable performance than that operated in closed circuit (C-MFC sensor) when affected by organic matter (NaAc). The sensitivity of O-MFC sensor was twice that of C-MFC sensor at a low background concentration of organic matter. When organic matter reached a high concentration, the sensitivity of O-MFC sensor remained at an acceptable level, while that of C-MFC sensor dropped to almost zero. Challenged by a combined shock of organic matter and nitrate, O-MFC sensor delivered evident electrical signals for nitrate warning, while C-MFC failed. Another novel feature of this study lies in a new mathematical model to examine the bioanode process of nitrate monitoring. It revealed that lower capacitance of the bioanode in O-MFC was the major contributor to the improved sensitivity of the device. Copyright © 2018 Elsevier B.V. All rights reserved.

Numerical study on AC loss reduction of stacked HTS tapes by optimal design of flux diverter

NASA Astrophysics Data System (ADS)

Liu, Guole; Zhang, Guomin; Jing, Liwei; Yu, Hui

2017-12-01

High temperature superconducting (HTS) coils are key parts of many AC applications, such as generators, superconducting magnetic energy storage and transformers. AC loss reduction in HTS coils is essential for the commercialization of these HTS devices. Magnetic material is generally used as the flux diverter in an effort to reduce the AC loss in HTS coils. To achieve the greatest reduction in the AC loss of the coils, the flux diverter should be made of a material with low loss and high saturated magnetic density, and the optimization of the geometric size and location of the flux diverter is required. In this paper, we chose Ni-alloy as the flux diverter, which can be processed into a specific shape and size. The influence of the shape and location of the flux diverter on the AC loss characteristics of stacked (RE)BCO tapes is investigated by use of a finite element method. Taking both the AC loss of the (RE)BCO coils and the ferromagnetic loss of the flux diverter into account, the optimal geometry of the flux diverter is obtained. It is found that when the applied current is at half the value of the critical current, the total loss of the HTS stack with the optimal flux diverter is only 18% of the original loss of the HTS stack without the flux diverter. Besides, the effect of the flux diverter on the critical current of the (RE)BCO stack is investigated.

Long-term outcome of patients with acute cholecystitis receiving antibiotic treatment: a retrospective cohort study.

PubMed

Wang, Chih-Hung; Chou, Hao-Chang; Liu, Kao-Lang; Lien, Wan-Ching; Wang, Hsiu-Po; Wu, Yao-Ming

2014-02-01

Few studies have followed patients who received antibiotic treatment for acute cholecystitis (AC). The present retrospective study investigated recurrence rates of AC and analyzed factors associated with recurrence after antibiotic treatment in adult AC patients. We analyzed patients treated with antibiotics for AC between October 1, 2004, and November 30, 2010. A Cox proportional hazards model was used to identify factors associated with early recurrence. Generalized additive models were applied to detect the nonlinear effects of continuous covariates. The study included 226 patients (mean age: 62.2 years; 144 men [63.7 %]). The average duration of parenteral antibiotics was 8.0 days. Second-generation cephalosporins were administered to 199 patients (88.1 %). The Kaplan-Meier plot indicated that recurrences were more frequent within 100 days of AC; these were defined as early recurrences. The recurrence rate was 13.7 % (31/226) at a median follow-up of 308.5 days (early recurrences: 19/226 [8.4 %]). The duration of parenteral antibiotic use significantly correlated with early recurrence (hazard ratio: 0.83; 95 % confidence interval, 0.73-0.95; p = 0.005). Generalized additive models revealed that patients using parenteral antibiotics longer than 8 days were less likely to suffer from early recurrence. The rate of recurrence of AC in patients who received antibiotics alone was low. The recurrence rate was higher within 100 days of AC. Because of the inherent limitations of a retrospective study, further research is needed to identify factors associated with early recurrence.

Static Measurements on HTS Coils of Fully Superconducting AC Electric Machines for Aircraft Electric Propulsion System

NASA Technical Reports Server (NTRS)

Choi, Benjamin B.; Hunker, Keith R.; Hartwig, Jason; Brown, Gerald V.

2017-01-01

The NASA Glenn Research Center (GRC) has been developing the high efficiency and high-power density superconducting (SC) electric machines in full support of electrified aircraft propulsion (EAP) systems for a future electric aircraft. A SC coil test rig has been designed and built to perform static and AC measurements on BSCCO, (RE)BCO, and YBCO high temperature superconducting (HTS) wire and coils at liquid nitrogen (LN2) temperature. In this paper, DC measurements on five SC coil configurations of various geometry in zero external magnetic field are measured to develop good measurement technique and to determine the critical current (Ic) and the sharpness (n value) of the super-to-normal transition. Also, standard procedures for coil design, fabrication, coil mounting, micro-volt measurement, cryogenic testing, current control, and data acquisition technique were established. Experimentally measured critical currents are compared with theoretical predicted values based on an electric-field criterion (Ec). Data here are essential to quantify the SC electric machine operation limits where the SC begins to exhibit non-zero resistance. All test data will be utilized to assess the feasibility of using HTS coils for the fully superconducting AC electric machine development for an aircraft electric propulsion system.

Ion-selective detection by plasticized poly(vinyl chloride) membrane in glass nanopipette with alternating voltage modulation.

PubMed

Deng, Xiao Long; Takami, Tomohide; Son, Jong Wan; Kang, Eun Ji; Kawai, Tomoji; Park, Bae Ho

2013-08-01

An alternating current (AC) voltage modulation was applied to ion-selective observations with plasticized poly(vinyl chloride) membranes in glass nanopipettes. The liquid confronting the membranes in the nanopipettes, the conditioning process, and AC voltage modulation play important roles in the ion-selective detection. In the AC detection system developed by us, where distilled water was used as the liquid within the nanopipettes, potassium ions were selectively detected in the sample solution of sodium and potassium ions because sodium ions were captured at the membrane containing bis(12-crown-4) ionophores, before the saturation of the ionophores. The membrane lost the selectivity after the saturation. On using sodium chloride as the liquid within the nanopipette, the membrane selectively detected potassium and sodium ions before and after the saturation of ionophores, respectively. The ion-selective detection of our system can be explained by the ion extraction-diffusion-dissolution mechanism through the bis(12-crown-4) ionophores with AC voltage modulation.

Hamiltonian methods of modeling and control of AC microgrids with spinning machines and inverters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthews, Ronald C.; Weaver, Wayne W.; Robinett, Rush D.

This study presents a novel approach to the modeling and control of AC microgrids that contain spinning machines, power electronic inverters and energy storage devices. The inverters in the system can adjust their frequencies and power angles very quickly, so the modeling focuses on establishing a common reference frequency and angle in the microgrid based on the spinning machines. From this dynamic model, nonlinear Hamiltonian surface shaping and power flow control method is applied and shown to stabilize. From this approach the energy flow in the system is used to show the energy storage device requirements and limitations for themore » system. This paper first describes the model for a single bus AC microgrid with a Hamiltonian control, then extends this model and control to a more general class of multiple bus AC microgrids. Finally, simulation results demonstrate the efficacy of the approach in stabilizing and optimization of the microgrid.« less

Hamiltonian methods of modeling and control of AC microgrids with spinning machines and inverters

DOE PAGES

Matthews, Ronald C.; Weaver, Wayne W.; Robinett, Rush D.; ...

2017-12-22

This study presents a novel approach to the modeling and control of AC microgrids that contain spinning machines, power electronic inverters and energy storage devices. The inverters in the system can adjust their frequencies and power angles very quickly, so the modeling focuses on establishing a common reference frequency and angle in the microgrid based on the spinning machines. From this dynamic model, nonlinear Hamiltonian surface shaping and power flow control method is applied and shown to stabilize. From this approach the energy flow in the system is used to show the energy storage device requirements and limitations for themore » system. This paper first describes the model for a single bus AC microgrid with a Hamiltonian control, then extends this model and control to a more general class of multiple bus AC microgrids. Finally, simulation results demonstrate the efficacy of the approach in stabilizing and optimization of the microgrid.« less

Superconducting shielded core reactor with reduced AC losses

DOEpatents

Cha, Yung S.; Hull, John R.

2006-04-04

A superconducting shielded core reactor (SSCR) operates as a passive device for limiting excessive AC current in a circuit operating at a high power level under a fault condition such as shorting. The SSCR includes a ferromagnetic core which may be either closed or open (with an air gap) and extends into and through a superconducting tube or superconducting rings arranged in a stacked array. First and second series connected copper coils each disposed about a portion of the iron core are connected to the circuit to be protected and are respectively wound inside and outside of the superconducting tube or rings. A large impedance is inserted into the circuit by the core when the shielding capability of the superconducting arrangement is exceeded by the applied magnetic field generated by the two coils under a fault condition to limit the AC current in the circuit. The proposed SSCR also affords reduced AC loss compared to conventional SSCRs under continuous normal operation.

Influence of temperature on AC conductivity of nanocrystalline CuAlO2

NASA Astrophysics Data System (ADS)

Prakash, T.

2012-07-01

Nanocrystalline CuAlO2 was synthesized by mechanical alloying of Cu2O and α-Al2O3 powders in the molar ratio of 1:1 for 20 h in toluene medium with tungsten carbide balls and vials using planetary ball mill. The ball milling was carried out at 300 rpm with a ball to powder weight ratio of 10:1 and then annealed at 1373 K in a platinum crucible for 20 h to get CuAlO2 phase with average crystallite size 45 nm. Complex impedance spectroscopic measurement in the frequency region 1 Hz to 10 MHz between the temperatures 333 to 473 K was carried out for nanocrystalline CuAlO2 sample. The obtained complex impedance data was analyzed for AC conductivities, DC and AC conductivities correlations and crossover frequencies ( f co ). The BNN (Barton, Nakajima and Namikawa) relation was applied to understand the correlation between DC and AC conductivities. The observed experimental results were discussed in the paper.

Application of Box-Behnken experimental design to optimize the extraction of insecticidal Cry1Ac from soil.

PubMed

Li, Yan-Liang; Fang, Zhi-Xiang; You, Jing

2013-02-20

A validated method for analyzing Cry proteins is a premise to study the fate and ecological effects of contaminants associated with genetically engineered Bacillus thuringiensis crops. The current study has optimized the extraction method to analyze Cry1Ac protein in soil using a response surface methodology with a three-level-three-factor Box-Behnken experimental design (BBD). The optimum extraction conditions were at 21 °C and 630 rpm for 2 h. Regression analysis showed a good fit of the experimental data to the second-order polynomial model with a coefficient of determination of 0.96. The method was sensitive and precise with a method detection limit of 0.8 ng/g dry weight and relative standard deviations at 7.3%. Finally, the established method was applied for analyzing Cry1Ac protein residues in field-collected soil samples. Trace amounts of Cry1Ac protein were detected in the soils where transgenic crops have been planted for 8 and 12 years.

Driving Human Motor Cortical Oscillations Leads to Behaviorally Relevant Changes in Local GABAA Inhibition: A tACS-TMS Study.

PubMed

Nowak, Magdalena; Hinson, Emily; van Ede, Freek; Pogosyan, Alek; Guerra, Andrea; Quinn, Andrew; Brown, Peter; Stagg, Charlotte J

2017-04-26

Beta and gamma oscillations are the dominant oscillatory activity in the human motor cortex (M1). However, their physiological basis and precise functional significance remain poorly understood. Here, we used transcranial magnetic stimulation (TMS) to examine the physiological basis and behavioral relevance of driving beta and gamma oscillatory activity in the human M1 using transcranial alternating current stimulation (tACS). tACS was applied using a sham-controlled crossover design at individualized intensity for 20 min and TMS was performed at rest (before, during, and after tACS) and during movement preparation (before and after tACS). We demonstrated that driving gamma frequency oscillations using tACS led to a significant, duration-dependent decrease in local resting-state GABA A inhibition, as quantified by short interval intracortical inhibition. The magnitude of this effect was positively correlated with the magnitude of GABA A decrease during movement preparation, when gamma activity in motor circuitry is known to increase. In addition, gamma tACS-induced change in GABA A inhibition was closely related to performance in a motor learning task such that subjects who demonstrated a greater increase in GABA A inhibition also showed faster short-term learning. The findings presented here contribute to our understanding of the neurophysiological basis of motor rhythms and suggest that tACS may have similar physiological effects to endogenously driven local oscillatory activity. Moreover, the ability to modulate local interneuronal circuits by tACS in a behaviorally relevant manner provides a basis for tACS as a putative therapeutic intervention. SIGNIFICANCE STATEMENT Gamma oscillations have a vital role in motor control. Using a combined tACS-TMS approach, we demonstrate that driving gamma frequency oscillations modulates GABA A inhibition in the human motor cortex. Moreover, there is a clear relationship between the change in magnitude of GABA A inhibition induced by tACS and the magnitude of GABA A inhibition observed during task-related synchronization of oscillations in inhibitory interneuronal circuits, supporting the hypothesis that tACS engages endogenous oscillatory circuits. We also show that an individual's physiological response to tACS is closely related to their ability to learn a motor task. These findings contribute to our understanding of the neurophysiological basis of motor rhythms and their behavioral relevance and offer the possibility of developing tACS as a therapeutic tool. Copyright © 2017 Nowak et al.

Active vibration control of structures undergoing bending vibrations

NASA Technical Reports Server (NTRS)

Pla, Frederic G. (Inventor); Rajiyah, Harindra (Inventor)

1995-01-01

An active vibration control subassembly for a structure (such as a jet engine duct or a washing machine panel) undergoing bending vibrations caused by a source (such as the clothes agitator of the washing machine) independent of the subassembly. A piezoceramic actuator plate is vibratable by an applied electric AC signal. The plate is connected to the structure such that vibrations in the plate induced by the AC signal cause canceling bending vibrations in the structure and such that the plate is compressively pre-stressed along the structure when the structure is free of any bending vibrations. The compressive prestressing increases the amplitude of the canceling bending vibrations before the critical tensile stress level of the plate is reached. Preferably, a positive electric DC bias is also applied to the plate in its poling direction.

Ion peak narrowing by applying additional AC voltage (ripple voltage) to FAIMS extractor electrode.

PubMed

Pervukhin, Viktor V; Sheven, Dmitriy G

2010-01-01

The use of a non-uniform electric field in a high-field asymmetric waveform ion mobility spectrometry (FAIMS) analyzer increases sensitivity but decreases resolution. The application of an additional AC voltage to the extractor electrode ("ripple" voltage, U(ripple)) can overcome this effect, which decreases the FAIMS peak width. In this approach, the diffusion ion loss remains minimal in the non-uniform electric field in the cylindrical part of the device, and all ion losses under U(ripple) occur in a short portion of their path. Application of the ripple voltage to the extractor electrode is twice as efficient as the applying of U(ripple) along the total length of the device. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.

Quantitative structure-activity relationships for reactivities of sulfate and hydroxyl radicals with aromatic contaminants through single-electron transfer pathway.

PubMed

Luo, Shuang; Wei, Zongsu; Spinney, Richard; Villamena, Frederick A; Dionysiou, Dionysios D; Chen, Dong; Tang, Chong-Jian; Chai, Liyuan; Xiao, Ruiyang

2018-02-15

Sulfate radical anion (SO 4 •- ) and hydroxyl radical (OH) based advanced oxidation technologies has been extensively used for removal of aromatic contaminants (ACs) in waters. In this study, we investigated the Gibbs free energy (ΔG SET ∘ ) of the single electron transfer (SET) reactions for 76 ACs with SO 4 •- and OH, respectively. The result reveals that SO 4 •- possesses greater propensity to react with ACs through the SET channel than OH. We hypothesized that the electron distribution within the molecule plays an essential role in determining the ΔG SET ∘ and subsequent SET reactions. To test the hypothesis, a quantitative structure-activity relationship (QSAR) model was developed for predicting ΔG SET ∘ using the highest occupied molecular orbital energies (E HOMO ), a measure of electron distribution and donating ability. The standardized QSAR models are reported to be ΔG ° SET =-0.97×E HOMO - 181 and ΔG ° SET =-0.97×E HOMO - 164 for SO 4 •- and OH, respectively. The models were internally and externally validated to ensure robustness and predictability, and the application domain and limitations were discussed. The single-descriptor based models account for 95% of the variability for SO 4 •- and OH. These results provide the mechanistic insight into the SET reaction pathway of radical and non-radical bimolecular reactions, and have important applications for radical based oxidation technologies to remove target ACs in different waters. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites.

PubMed

Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan

2016-02-20

Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data.

Asia-Pacific consensus statement on the optimal use of high-sensitivity troponin assays in acute coronary syndromes diagnosis: focus on hs-TnI

PubMed Central

Tan, Jack Wei Chieh; Lam, Carolyn S P; Kasim, Sazzli Shahlan; Aw, Tar Choon; Abanilla, Joel M; Chang, Wei-Ting; Dang, Van Phuoc; Iboleon-Dy, Maria; Mumpuni, Sari Sri; Phommintikul, Arintaya; Ta, Manh Cuong; Topipat, Punkiat; Yiu, Kai Hang; Cullen, Louise

2017-01-01

Objective High-sensitivity troponin (hs-Tn) assays need to be applied appropriately to improve diagnosis and patient outcomes in acute coronary syndromes (ACS). Methods Experts from Asia Pacific convened in 2015 to provide data-driven consensus-based, region-specific recommendations and develop an algorithm for the appropriate incorporation of this assay into the ACS assessment and treatment pathway. Results Nine recommendations were developed by the expert panel: (1) troponin is the preferred cardiac biomarker for diagnostic assessment of ACS and is indicated for patients with symptoms of possible ACS; (2) hs-Tn assays are recommended; (3) serial testing is required for all patients; (4) testing should be performed at presentation and 3 hours later; (5) gender-specific cut-off values should be used for hs-Tn I assays; (6) hs-Tn I level >10 times the upper limit of normal should be considered to ‘rule in’ a diagnosis of ACS; (7) dynamic change >50% in hs-Tn I level from presentation to 3-hour retest identifies patients at high risk for ACS; (8) where only point-of-care testing is available, patients with elevated readings should be considered at high risk, while patients with low/undetectable readings should be retested after 6 hours or sent for laboratory testing and (9) regular education on the appropriate use of troponin tests is essential. Conclusions We propose an algorithm that will potentially reduce delays in discharge by the accurate ‘rule out’ of non-ACS patients within 3 hours. Appropriate research should be undertaken to ensure the efficacy and safety of the algorithm in clinical practice, with the long-term goal of improvement of care of patients with ACS in Asia Pacific. PMID:28466882

Outcomes associated with comorbid atrial fibrillation and heart failure in Medicare beneficiaries with acute coronary syndrome.

PubMed

Chen, Shih-Yin; Crivera, Concetta; Stokes, Michael; Boulanger, Luke; Schein, Jeff

2014-02-20

Atrial fibrillation (AF) and heart failure (HF) are both common comorbid conditions of elderly patients with acute coronary syndrome (ACS), but published data on their associated clinical and economic outcomes are limited. Our study included patients from the Medicare Current Beneficiary Survey with an incident hospitalization for ACS between 03/01/2002 and 12/31/2006. Applying population weights, we identified 795 incident ACS patients, representing more than 2.5 million Medicare beneficiaries. Of this population, 13.1% had comorbid AF, and 22.9% had HF, which were identified from Medicare claims during the 6 months prior to the first ACS event (index date) Subsequent cardiovascular (CV) hospitalizations and mortality were compared using Kaplan-Meier curves. Cox proportional hazards regressions were used to estimate the relative risk of AF and HF on CV events and mortality. Healthcare costs were summarized for the calendar year in which the incident ACS event occurred. HF was associated with a 41% higher risk of mortality (HR = 1.41; 95% confidence interval [CI] 1.05-1.89). Both AF (HR = 1.46; 95% CI 1.14-1.87) and HF (HR = 1.61; 95% CI 1.26-2.06) were associated with higher risks of subsequent CV events. During the year of the incident ACS event, ACS patients with comorbid AF or HF had approximately $18,000 higher total healthcare costs than those without these comorbidities. Using a nationally representative sample of Medicare beneficiaries, we observed a significantly higher clinical and economic burden of patients hospitalized for ACS with comorbid AF and HF compared with those without these conditions.

Non-invasive diagnosis and monitoring of actinic cheilitis with reflectance confocal microscopy.

PubMed

Ulrich, M; González, S; Lange-Asschenfeldt, B; Roewert-Huber, J; Sterry, W; Stockfleth, E; Astner, S

2011-03-01

Actinic cheilitis (AC) represents the equivalent of actinic keratosis on the lip. Various treatment modalities are available and the efficacy of diclofenac in hyaluronic acid has recently been described. Reflectance confocal microscopy (RCM) is a non-invasive imaging technique which has recently been applied for the diagnosis of actinic keratoses. Herein, we describe the applicability of RCM for the diagnosis of AC and for monitoring of treatment response of AC to diclofenac in hyaluronic acid. Ten Caucasian patients with clinical suspicion for AC were included in this study. To obtain a non-invasive diagnosis, RCM was performed at baseline, followed by biopsy and respective confocal-histopathological correlation. Six patients with a histological diagnosis of AC were treated with diclofenac in hyaluronic acid, whereby monitoring was performed by RCM. Reflectance confocal microscopy was able to correctly identify 6/7 cases of AC and 3/3 cases of benign lesions. The most important RCM criteria for diagnosis of AC were cellular atypia at the stratum spinosum and granulosum with atypical honeycomb pattern. One patient with AC was misclassified as inflammatory cheilitis by RCM as it showed marked inflammatory response and lacked clear signs of cellular atypia on RCM imaging. Following topical treatment with diclofenac gel, 5/6 patients (83%) showed a good treatment response with regression of dysplasia on consecutive RCM examination. Reflectance confocal microscopy is a promising tool for the non-invasive diagnosis and monitoring of actinic cheilitis. However, marked inflammation represents a potential diagnostic pitfall. In this regard, biopsy should be performed in doubtful cases. © 2010 The Authors. Journal of the European Academy of Dermatology and Venereology © 2010 European Academy of Dermatology and Venereology.

Functionalized TiO2 nanoparticles labelled with 225Ac for targeted alpha radionuclide therapy.

PubMed

Cędrowska, Edyta; Pruszynski, Marek; Majkowska-Pilip, Agnieszka; Męczyńska-Wielgosz, Sylwia; Bruchertseifer, Frank; Morgenstern, Alfred; Bilewicz, Aleksander

2018-01-01

The 225 Ac radioisotope exhibits very attractive nuclear properties for application in radionuclide therapy. Unfortunately, the major challenge for radioconjugates labelled with 225 Ac is that traditional chelating moieties are unable to sequester the radioactive daughters in the bioconjugate which is critical to minimize toxicity to healthy, non-targeted tissues. In the present work, we propose to apply TiO 2 nanoparticles (NPs) as carrier for 225 Ac and its decay products. The surface of TiO 2 nanoparticles with 25 nm diameter was modified with Substance P (5-11), a peptide fragment which targets NK1 receptors on the glioma cells, through the silan-PEG-NHS linker. Nanoparticles functionalized with Substance P (5-11) were synthesized with high yield in a two-step procedure, and the products were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and thermogravimetric analysis (TGA). The obtained results show that one TiO 2 -bioconjugate nanoparticle contains in average 80 peptide molecules on its surface. The synthesized TiO 2 -PEG-SP(5-11) conjugates were labelled with 225 Ac by ion-exchange reaction on hydroxyl (OH) functional groups on the TiO 2 surface. The labelled bioconjugates almost quantitatively retain 225 Ac in phosphate-buffered saline (PBS), physiological salt and cerebrospinal fluid (CSF) for up to 10 days. The leaching of 221 Fr, a first decay daughter of 225 Ac, in an amount of 30% was observed only in CSF after 10 days. The synthesized 225 Ac-TiO 2 -PEG-SP(5-11) has shown high cytotoxic effect in vitro in T98G glioma cells; therefore, it is a promising new radioconjugate for targeted radionuclide therapy of brain tumours.

Functionalized TiO2 nanoparticles labelled with 225Ac for targeted alpha radionuclide therapy

NASA Astrophysics Data System (ADS)

Cędrowska, Edyta; Pruszynski, Marek; Majkowska-Pilip, Agnieszka; Męczyńska-Wielgosz, Sylwia; Bruchertseifer, Frank; Morgenstern, Alfred; Bilewicz, Aleksander

2018-03-01

The 225Ac radioisotope exhibits very attractive nuclear properties for application in radionuclide therapy. Unfortunately, the major challenge for radioconjugates labelled with 225Ac is that traditional chelating moieties are unable to sequester the radioactive daughters in the bioconjugate which is critical to minimize toxicity to healthy, non-targeted tissues. In the present work, we propose to apply TiO2 nanoparticles (NPs) as carrier for 225Ac and its decay products. The surface of TiO2 nanoparticles with 25 nm diameter was modified with Substance P (5-11), a peptide fragment which targets NK1 receptors on the glioma cells, through the silan-PEG-NHS linker. Nanoparticles functionalized with Substance P (5-11) were synthesized with high yield in a two-step procedure, and the products were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and thermogravimetric analysis (TGA). The obtained results show that one TiO2-bioconjugate nanoparticle contains in average 80 peptide molecules on its surface. The synthesized TiO2-PEG-SP(5-11) conjugates were labelled with 225Ac by ion-exchange reaction on hydroxyl (OH) functional groups on the TiO2 surface. The labelled bioconjugates almost quantitatively retain 225Ac in phosphate-buffered saline (PBS), physiological salt and cerebrospinal fluid (CSF) for up to 10 days. The leaching of 221Fr, a first decay daughter of 225Ac, in an amount of 30% was observed only in CSF after 10 days. The synthesized 225Ac-TiO2-PEG-SP(5-11) has shown high cytotoxic effect in vitro in T98G glioma cells; therefore, it is a promising new radioconjugate for targeted radionuclide therapy of brain tumours.

Non-linear transfer characteristics of stimulation and recording hardware account for spurious low-frequency artifacts during amplitude modulated transcranial alternating current stimulation (AM-tACS).

PubMed

Kasten, Florian H; Negahbani, Ehsan; Fröhlich, Flavio; Herrmann, Christoph S

2018-05-31

Amplitude modulated transcranial alternating current stimulation (AM-tACS) has been recently proposed as a possible solution to overcome the pronounced stimulation artifact encountered when recording brain activity during tACS. In theory, AM-tACS does not entail power at its modulating frequency, thus avoiding the problem of spectral overlap between brain signal of interest and stimulation artifact. However, the current study demonstrates how weak non-linear transfer characteristics inherent to stimulation and recording hardware can reintroduce spurious artifacts at the modulation frequency. The input-output transfer functions (TFs) of different stimulation setups were measured. Setups included recordings of signal-generator and stimulator outputs and M/EEG phantom measurements. 6 th -degree polynomial regression models were fitted to model the input-output TFs of each setup. The resulting TF models were applied to digitally generated AM-tACS signals to predict the frequency of spurious artifacts in the spectrum. All four setups measured for the study exhibited low-frequency artifacts at the modulation frequency and its harmonics when recording AM-tACS. Fitted TF models showed non-linear contributions significantly different from zero (all p < .05) and successfully predicted the frequency of artifacts observed in AM-signal recordings. Results suggest that even weak non-linearities of stimulation and recording hardware can lead to spurious artifacts at the modulation frequency and its harmonics. These artifacts were substantially larger than alpha-oscillations of a human subject in the MEG. Findings emphasize the need for more linear stimulation devices for AM-tACS and careful analysis procedures, taking into account low-frequency artifacts to avoid confusion with effects of AM-tACS on the brain. Copyright © 2018 Elsevier Inc. All rights reserved.

Abundance of Dioxygenase Genes Similar to Ralstonia sp. Strain U2 nagAc Is Correlated with Naphthalene Concentrations in Coal Tar-Contaminated Freshwater Sediments

PubMed Central

Dionisi, Hebe M.; Chewning, Christopher S.; Morgan, Katherine H.; Menn, Fu-Min; Easter, James P.; Sayler, Gary S.

2004-01-01

We designed a real-time PCR assay able to recognize dioxygenase large-subunit gene sequences with more than 90% similarity to the Ralstonia sp. strain U2 nagAc gene (nagAc-like gene sequences) in order to study the importance of organisms carrying these genes in the biodegradation of naphthalene. Sequencing of PCR products indicated that this real-time PCR assay was specific and able to detect a variety of nagAc-like gene sequences. One to 100 ng of contaminated-sediment total DNA in 25-μl reaction mixtures produced an amplification efficiency of 0.97 without evident PCR inhibition. The assay was applied to surficial freshwater sediment samples obtained in or in close proximity to a coal tar-contaminated Superfund site. Naphthalene concentrations in the analyzed samples varied between 0.18 and 106 mg/kg of dry weight sediment. The assay for nagAc-like sequences indicated the presence of (4.1 ± 0.7) × 103 to (2.9 ± 0.3) × 105 copies of nagAc-like dioxygenase genes per μg of DNA extracted from sediment samples. These values corresponded to (1.2 ± 0.6) × 105 to (5.4 ± 0.4) × 107 copies of this target per g of dry weight sediment when losses of DNA during extraction were taken into account. There was a positive correlation between naphthalene concentrations and nagAc-like gene copies per microgram of DNA (r = 0.89) and per gram of dry weight sediment (r = 0.77). These results provide evidence of the ecological significance of organisms carrying nagAc-like genes in the biodegradation of naphthalene. PMID:15240274

Scalable synthesis of hierarchical macropore-rich activated carbon microspheres assembled by carbon nanoparticles for high rate performance supercapacitors

NASA Astrophysics Data System (ADS)

Zhang, Dongdong; Zhao, Jianghong; Feng, Chong; Zhao, Rijie; Sun, Yahui; Guan, Taotao; Han, Baixin; Tang, Nan; Wang, Jianlong; Li, Kaixi; Qiao, Jinli; Zhang, Jiujun

2017-02-01

A scalable inverse-microemulsion-polymerization-phase-separation coupling method is applied to successfully prepare hierarchical macropore-rich activated carbon microspheres (ACS) using a phenolic resin (PR) precursor followed by carbonization and KOH activation for the first time. The formed ACS materials are assembled by carbon nanoparticles (CNPs). The macropores interspersed among the component CNPs are formed after removing the non-reactive solvent phase in the course of the polymerization of the reactive PR phase, which occupies ∼64% of the total pore volume (∼2.779 cm3 g-1) of the optimized ACS. In combination with mesopores (∼18% of the total pore volume), the ACS possesses meso/macropores approaching 82% of the total pore volume. Micropores are created in the component CNPs via KOH activation, showing shortened ion transport distances in the nanoscale dimension. Both the hierarchical micro/meso/macroporous structure and the inner nanoparticle morphology (short ion diffusion pathways) can significantly contribute to the rapid transport of electrolyte ions throughout the carbonaceous matrix, resulting in superior rate performance of ACS-based supercapacitors. More importantly, the energy densities of the ACS supercapacitors operating in both aqueous and organic electrolyte retain steady over a wide range of power densities varying dramatically from 0.25 to 14.5 kW kg-1 and to 7.0 kW kg-1, respectively.

Production of highly efficient activated carbons from industrial wastes for the removal of pharmaceuticals from water-A full factorial design.

PubMed

Jaria, Guilaine; Silva, Carla Patrícia; Oliveira, João A B P; Santos, Sérgio M; Gil, María Victoria; Otero, Marta; Calisto, Vânia; Esteves, Valdemar I

2018-02-26

The wide occurrence of pharmaceuticals in aquatic environments urges the development of cost-effective solutions for their removal from water. In a circular economy context, primary paper mill sludge (PS) was used to produce activated carbon (AC) aiming the adsorptive removal of these contaminants. The use of low-cost precursors for the preparation of ACs capable of competing with commercial ACs continues to be a challenge. A full factorial design of four factors (pyrolysis temperature, residence time, precursor/activating agent ratio, and type of activating agent) at two levels was applied to the production of AC using PS as precursor. The responses analysed were the yield of production, percentage of adsorption for three pharmaceuticals (sulfamethoxazole, carbamazepine, and paroxetine), specific surface area (S BET ), and total organic carbon (TOC). Statistical analysis was performed to evaluate influencing factors in the responses and to determine the most favourable production conditions. Four ACs presented very good responses, namely on the adsorption of the pharmaceuticals under study (average adsorption percentage around 78%, which is above that of commercial AC), and S BET between 1389 and 1627 m 2  g -1 . A desirability analysis pointed out 800 °C for 60 min and a precursor/KOH ratio of 1:1 (w/w) as the optimal production conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellis, D.E.; Gubanov, V.A.; Rosen, A.

The electronic structure of actinide monoxides AcO and dioxides AcO/sub 2/, where Ac = Th, U, Np, Pu, Am, Cm and Bk has been studied by molecular cluster methods based on the first-principles one-electron local density theory. Molecular orbitals for nearest neighbor clusters AcO/sup 10 -//sub 6/ and AcO/sup 12 -//sub 8/ representative of monoxide and dioxide lattices were obtained using non-relativistic spin-restricted and spin-polarized Hartree-Fock-Slater models for the entire series. Fully relativistic Dirac-Slater calculations were performed for ThO, UO and NpO in order to explore magnitude of spin-orbit splittings and level shifts in valence structure. Self-consistent iterations were carriedmore » out for NpO, in which the NpO/sub 6/ cluster was embedded in the molecular field of the solid. Finally, a ''moment polarized'' model which combines both spin-polarization and relativistic effects in a consistent fashion was applied to the NpO system. Covalent mixing of oxygen 2p and Ac 5f orbitals was found to increase rapidly across the actinide series; metal s,p,d covalency was found to be nearly constant. Mulliken atomic population analysis of cluster eigenvectors shows that free-ion crystal field models are unreliable, except for the light actinides. X-ray photoelectron line shapes have been calculated and are found to compare rather well with experimental data on the dioxides.« less

Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

NASA Technical Reports Server (NTRS)

Gottardi, L.; Bruijn, M.; denHartog, R.; Hoevers, H.; deKorte, P.; vanderKuur, J.; Linderman, M.; Adams, J.; Bailey, C.; Bandler, S.;

The a.c. Josephson effect without superconductivity

PubMed Central

Gaury, Benoit; Weston, Joseph; Waintal, Xavier

2015-01-01

Superconductivity derives its most salient features from the coherence of the associated macroscopic wave function. The related physical phenomena have now moved from exotic subjects to fundamental building blocks for quantum circuits such as qubits or single photonic modes. Here we predict that the a.c. Josephson effect—which transforms a d.c. voltage Vb into an oscillating signal cos (2eVbt/ħ)—has a mesoscopic counterpart in normal conductors. We show that when a d.c. voltage Vb is applied to an electronic interferometer, there exists a universal transient regime where the current oscillates at frequency eVb/h. This effect is not limited by a superconducting gap and could, in principle, be used to produce tunable a.c. signals in the elusive 0.1–10-THz ‘terahertz gap’. PMID:25765929

Effect of externally applied periodic force on ion acoustic waves in superthermal plasmas

NASA Astrophysics Data System (ADS)

Chowdhury, Snigdha; Mandi, Laxmikanta; Chatterjee, Prasanta

2018-04-01

Ion acoustic solitary waves in superthermal plasmas are investigated in the presence of trapped electrons. The reductive perturbation technique is employed to obtain a forced Korteweg-de Vries-like Schamel equation. An analytical solution is obtained in the presence of externally applied force. The effect of the external applied periodic force is also observed. The effect of the spectral index (κ), the strength ( f 0 ) , and the frequency ( ω ) on the amplitude and width of the solitary wave is obtained. The result may be useful in laboratory plasma as well as space environments.

Predicting the risk of bleeding during dual antiplatelet therapy after acute coronary syndromes.

PubMed

Alfredsson, Joakim; Neely, Benjamin; Neely, Megan L; Bhatt, Deepak L; Goodman, Shaun G; Tricoci, Pierluigi; Mahaffey, Kenneth W; Cornel, Jan H; White, Harvey D; Fox, Keith Aa; Prabhakaran, Dorairaj; Winters, Kenneth J; Armstrong, Paul W; Ohman, E Magnus; Roe, Matthew T

2017-08-01

Dual antiplatelet therapy (DAPT) with aspirin + a P2Y12 inhibitor is recommended for at least 12 months for patients with acute coronary syndrome (ACS), with shorter durations considered for patients with increased bleeding risk. However, there are no decision support tools available to predict an individual patient's bleeding risk during DAPT treatment in the post-ACS setting. To develop a longitudinal bleeding risk prediction model, we analy sed 9240 patients with unstable angina/non-ST segment elevation myocardial infarction (NSTEMI) from the Targeted Platelet Inhibition to Clarify the Optimal Strategy to Medically Manage Acute Coronary Syndromes (TRILOGY ACS) trial, who were managed without revasculari sation and treated with DAPT for a median of 14.8 months. We identified 10 significant baseline predictors of non-coronary artery bypass grafting (CABG)-related Global Use of Strategies to Open Occluded Arteries (GUSTO) severe/life-threatening/moderate bleeding: age, sex, weight, NSTEMI (vs unstable angina), angiography performed before randomi sation, prior peptic ulcer disease, creatinine, systolic blood pressure, haemoglobin and treatment with beta-blocker. The five significant baseline predictors of Thrombolysis In Myocardial Infarction (TIMI) major or minor bleeding included age, sex, angiography performed before randomi sation, creatinine and haemoglobin. The models showed good predictive accuracy with Therneau's C- indices: 0.78 (SE = 0.024) for the GUSTO model and 0.67 (SE = 0.023) for the TIMI model. Internal validation with bootstrapping gave similar C -indices of 0.77 and 0.65, respectively. External validation demonstrated an attenuated C -index for the GUSTO model (0.69) but not the TIMI model (0.68). Longitudinal bleeding risks during treatment with DAPT in patients with ACS can be reliably predicted using selected baseline characteristics. The TRILOGY ACS bleeding models can inform risk -benefit considerations regarding the duration of DAPT following ACS. ClinicalTrials.gov identifier: https://clinicaltrials.gov/ct2/show/NCT00699998. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Principal network analysis: identification of subnetworks representing major dynamics using gene expression data

PubMed Central

Kim, Yongsoo; Kim, Taek-Kyun; Kim, Yungu; Yoo, Jiho; You, Sungyong; Lee, Inyoul; Carlson, George; Hood, Leroy; Choi, Seungjin; Hwang, Daehee

2011-01-01

Motivation: Systems biology attempts to describe complex systems behaviors in terms of dynamic operations of biological networks. However, there is lack of tools that can effectively decode complex network dynamics over multiple conditions. Results: We present principal network analysis (PNA) that can automatically capture major dynamic activation patterns over multiple conditions and then generate protein and metabolic subnetworks for the captured patterns. We first demonstrated the utility of this method by applying it to a synthetic dataset. The results showed that PNA correctly captured the subnetworks representing dynamics in the data. We further applied PNA to two time-course gene expression profiles collected from (i) MCF7 cells after treatments of HRG at multiple doses and (ii) brain samples of four strains of mice infected with two prion strains. The resulting subnetworks and their interactions revealed network dynamics associated with HRG dose-dependent regulation of cell proliferation and differentiation and early PrPSc accumulation during prion infection. Availability: The web-based software is available at: http://sbm.postech.ac.kr/pna. Contact: dhhwang@postech.ac.kr; seungjin@postech.ac.kr Supplementary information: Supplementary data are available at Bioinformatics online. PMID:21193522

Generalization of the Child-Langmuir law to the alternate extraction of positive and negative ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lafleur, T., E-mail: trevor.lafleur@lpp.polytechnique.fr; ONERA-The French Aerospace Lab, 91120 Palaiseau; Aanesland, A.

Using a combined analytical and simulation approach, we investigate positive and negative ion extraction between two electrodes from an ion-ion plasma source. With a square voltage waveform applied to the electrodes, we obtain approximate analytical solutions for the time-averaged extracted current densities, which are given simply by: J{sub p}{sup ac}=[α−fL√((M{sub p})/(q{sub p}V{sub 0}) )]J{sub p}{sup dc}, and J{sub n}{sup ac}=[(1−α)−fL√((M{sub n})/(q{sub n}V{sub 0}) )]J{sub n}{sup dc}, where J{sup ac} is the time-averaged current density, α is the square waveform duty cycle, f is the frequency, L is the electrode gap length, M is the ion mass, q is the ionmore » charge, V{sub 0} is the applied voltage amplitude, J{sup dc} is the dc extracted current density, and the subscripts p and n refer to positive and negative ions, respectively. In particular, if J{sup dc} is the dc space-charge limited current density, then these equations describe the square waveform generalization of the Child-Langmuir law.« less

Numerical Simulations of Flow Separation Control in Low-Pressure Turbines using Plasma Actuators

NASA Technical Reports Server (NTRS)

Suzen, Y. B.; Huang, P. G.; Ashpis, D. E.

2007-01-01

A recently introduced phenomenological model to simulate flow control applications using plasma actuators has been further developed and improved in order to expand its use to complicated actuator geometries. The new modeling approach eliminates the requirement of an empirical charge density distribution shape by using the embedded electrode as a source for the charge density. The resulting model is validated against a flat plate experiment with quiescent environment. The modeling approach incorporates the effect of the plasma actuators on the external flow into Navier Stokes computations as a body force vector which is obtained as a product of the net charge density and the electric field. The model solves the Maxwell equation to obtain the electric field due to the applied AC voltage at the electrodes and an additional equation for the charge density distribution representing the plasma density. The new modeling approach solves the charge density equation in the computational domain assuming the embedded electrode as a source therefore automatically generating a charge density distribution on the surface exposed to the flow similar to that observed in the experiments without explicitly specifying an empirical distribution. The model is validated against a flat plate experiment with quiescent environment.

Modeling resistive wall modes and disruptive instabilities with M3D-C1

NASA Astrophysics Data System (ADS)

Ferraro, Nm; Jardin, Sc; Pfefferle, D.

2016-10-01

Disruptive instabilities pose a significant challenge to the tokamak approach to magnetic fusion energy, and must be reliably avoided in a successful reactor. These instabilities generally involve rapid, global changes to the magnetic field, and electromagnetic interaction with surrounding conducting structures. Here we apply the extended-MHD code M3D-C1 to calculate the stability and evolution of disruptive modes, including their interaction with external conducting structures. The M3D-C1 model includes the effects of resistivity, equilibrium rotation, and resistive walls of arbitrary thickness, each of which may play important roles in the stability and evolution of disruptive modes. The strong stabilizing effect of rotation on resistive wall modes is explored and compared with analytic theory. The nonlinear evolution of vertical displacement events is also considered, including the evolution of non-axisymmetric instabilities that may arise during the current-quench phase of the disruption. It is found that the non-axisymmetric stability of the plasma during a VDE depends strongly on the thermal history of the plasma. This work is supported by US DOE Grant DE-AC02-09CH11466 and the SciDAC Center for Extended MHD Modeling.

NONDESTRUCTIVE EDDY CURRENT TESTING

DOEpatents

Renken, C.J. Jr.

1961-05-23

An eddy current testing device is described for measuring metal continuity independent of probe-to-sample spacing. An inductance would test probe is made a leg of a variable impedance bridge and the bridge is balanced with the probe away from the sample. An a-c signal is applied across the input terminals of the bridge circuit. As the probe is brought into proximity with the metal sample, the resulting impedance change in the probe gives an output signal from the bridge whose phase angle is proportional to the sample continuity and amplitude is proportional to the probe-tosample spacing. The output signal from the bridge is applied to a compensating network where, responsive to amplitude changes from the bridge output signal, a constant phased voltage output is maintained when the sample is continuous regardless of probe-to-sample spacing. A phase meter calibrated to read changes in resistivity of the metal sample measures the phase shift between the output of the compensating network and the original a-c signal applied to the bridge.

Opto electronic tweezers based smart sweeper for cells/micro-particles sorting

NASA Astrophysics Data System (ADS)

Verma, R. S.; Kumar, N.

2018-04-01

We report on use of opto-electronic tweezers based sorting approach, termed as smart sweepers, for sorting the microscopic particles by using the Dielectrophoretic (DEP) force response of cells on applied a.c. bias frequency. The applied a.c. bias was kept in negative DEP region, close to the crossover frequency of one of the particles. A line shaped intensity pattern, generated by a cylindrical lens, was scanned across the mixture sample. The particles whose cross over frequency was close to the applied bias frequency, experienced negligible negative DEP(n-DEP) force. On the other hand, the other type of particle experienced large repelling force and were forced to move along the scanning direction of the line shaped intensity profile. We, as a proof of concept, demonstrated the working principle of opto electronic smart sweepers by sweeping out the polystyrene particles from a mixture consisting of polystyrene microspheres (PSM) and red blood cells (RBCs) and leaving RBCs in the region of interest.

Moment distributions of clusters and molecules in the adiabatic rotor model

NASA Astrophysics Data System (ADS)

Ballentine, G. E.; Bertsch, G. F.; Onishi, N.; Yabana, K.

2008-01-01

We present a Fortran program to compute the distribution of dipole moments of free particles for use in analyzing molecular beams experiments that measure moments by deflection in an inhomogeneous field. The theory is the same for magnetic and electric dipole moments, and is based on a thermal ensemble of classical particles that are free to rotate and that have moment vectors aligned along a principal axis of rotation. The theory has two parameters, the ratio of the magnetic (or electric) dipole energy to the thermal energy, and the ratio of moments of inertia of the rotor. Program summaryProgram title:AdiabaticRotor Catalogue identifier:ADZO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZO_v1_0.html Program obtainable from:CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions:Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.:479 No. of bytes in distributed program, including test data, etc.:4853 Distribution format:tar.gz Programming language:Fortran 90 Computer:Pentium-IV, Macintosh Power PC G4 Operating system:Linux, Mac OS X RAM:600 Kbytes Word size:64 bits Classification:2.3 Nature of problem:The system considered is a thermal ensemble of rotors having a magnetic or electric moment aligned along one of the principal axes. The ensemble is placed in an external field which is turned on adiabatically. The problem is to find the distribution of moments in the presence of the external field. Solution method:There are three adiabatic invariants. The only nontrivial one is the action associated with the polar angle of the rotor axis with respect to external field. It is found by Newton's method. Running time:3 min on a 3 GHz Pentium IV processor.

Physiological basis of a steady endogenous current in rat lumbrical muscle

PubMed Central

1984-01-01

In an attempt to determine the mechanism by which rat skeletal muscle endplates generate a steady outward current, we measured the effects of several drugs (furosemide, bumetanide, 9-anthracene carboxylic acid [9- AC]) and changes in external ion concentration (Na+, K+, Cl-, Ba++) on resting membrane potential (Vm) and on the steady outward current. Each of the following treatments caused a 10-15-mV hyperpolarization of the membrane: replacement of extracellular Cl- with isethionate, addition of furosemide or bumetanide, and addition of 9-AC. These results suggest that Cl- is actively accumulated by the muscle fibers and that the equilibrium potential of Cl- is more positive than the membrane potential. Removal of external Na+ also caused a large hyperpolarization and is consistent with evidence in other tissues that active Cl- accumulation requires external Na+. The same treatments greatly reduced or abolished the steady outward current, with a time course that paralleled the changes in Vm. These results cannot be explained by a model in which the steady outward current is assumed to arise as a result of a nonuniform distribution of Na+ conductance, but they are consistent with models in which the steady current is produced by a nonuniform distribution of GCl or GK. Other treatments (Na+-free and K+-free solutions, and 50 microM BaCl2) caused a temporary reversal of the steady current. Parallel measurements of Vm suggested that in none of these cases did the electrochemical driving force for K+ change sign, which makes it unlikely that the steady current arises as a result of a nonuniform distribution of GK. All of the results, however, are consistent with a model in which the steady outward current arises as a result of a nonuniform distribution of Cl- conductance, with GCl lower near the endplate than in extrajunctional regions. PMID:6325581

A magnetic-piezoelectric smart material-structure sensing three axis DC and AC magnetic-fields

NASA Astrophysics Data System (ADS)

Hung, Chiao-Fang; Chen, Chin-Chung; Yeh, Po-Chen; Chen, Po-Wen; Chung, Tien-Kan

2017-12-01

In this paper, we demonstrate a smart material-structure can sense not only three-axis AC magnetic-fields but also three-axis DC magnetic-fields. Under x-axis and z-axis AC magnetic field ranging from 0.2 to 3.2 gauss, sensing sensitivity of the smart material-structure stimulated at resonant frequency is approximate 8.79 and 2.80 mV/gauss, respectively. In addition, under x-axis and z-axis DC magnetic fields ranging from 2 to 12 gauss, the sensitivity of the smart material-structure is 1.24-1.54 and 1.25-1.41 mV/gauss, respectively. In addition, under x-axis and z-axis DC magnetic fields ranging from 12 to 20 gauss, the sensitivity of the smart material-structure is 5.17-6.2 and 3.97-4.57 mV/gauss, respectively. These experimental results show that the smart material-structure successfully achieves three-axis DC and AC magnetic sensing as we designed. Furthermore, we also compare the results of the AC and DC magnetic-field sensing to investigate discrepancies. Finally, when applying composite magnetic-fields to the smart material-structure, the smart material-structure shows decent outputs as expected (consistent to the sensing principle). In the future, we believe the smart material-structure capable of sensing AC and DC magnetic fields will have more applications than conventional structures capable of sensing only DC or AC magnetic field. Thus, the smart material-structure will be an important design reference for future magnetic-field sensing technologies.

A pilot trial of bordered polyurethane dressings, tissue adhesive and sutureless devices compared with standard polyurethane dressings for securing short-term arterial catheters.

PubMed

Edwards, Melannie; Rickard, Claire M; Rapchuk, Ivan; Corley, Amanda; Marsh, Nicole; Spooner, Amy J; Mihala, Gabor; Fraser, John F

2014-09-01

To improve arterial catheter (AC) securement and reduce AC failure; to assess feasibility of a large randomised controlled trial. A four-arm, parallel, randomised, controlled, non-blinded pilot trial with 195 intensive care patients taking part, in a tertiary referral hospital in Brisbane, Australia from May to November 2012. Standard polyurethane (SPU) dressing (controls); bordered polyurethane (BPU) + SPU dressing; tissue adhesive (TA) + SPU dressing; and sutureless securement device (SSD) + SPU dressing (no sutures used). AC failure, ie, complete dislodgement, occlusion (monitor failure, inability to infuse or fluid leaking), pain or infection (local or blood). Median AC dwell time was 26.2 hours and was comparable between groups. AC failure occurred in 26/195 patients (13%). AC failure was significantly worse with SPU dressings (10/47 [21%]) than with BPU + SPU dressings (2/ 43 [5%]; P = 0.03), but not significantly different to TA + SPU (6/56 [11%]; P = 0.18) or SSD + SPU (8/49 [16%]; P = 0.61). The dressing applied at AC insertion lasted until AC removal in 68% of controls; 56% of BPU + SPU dressings; 73% of TA + SPU dressings; and 80% of SSD + SPU dressings (all P > 0.05). There were no infections or serious adverse events. Patient and staff satisfaction with all products was high. Median costs (labour and materials) for securement per patient were significantly higher in all groups compared with the control group (SPU, $3.48 [IQR, $3.48-$9.79]; BPU + SPU, $5.07 [IQR, $5.07-$12.99]; SSD + SPU, $10.90 [IQR, $10.90-$10.90]; TA + SPU, $17.70 [IQR, $17.70-$38.36]; all P < 0.01). AC failure occurred significantly less often with BPU + SPU dressings than with SPU dressings. TA + SPU and SSD + SPU dressings should be further investigated and compared with BPU + SPU dressings as controls. The novel approach of TA + SPU dressings appeared safe and feasible.

Enhanced platelet/endothelial activation in depressed patients with acute coronary syndromes: evidence from recent clinical trials.

PubMed

Serebruany, Victor L; Glassman, Alexander H; Malinin, Alex I; Sane, David C; Finkel, Mitchell S; Krishnan, Ranga R; Atar, Dan; Lekht, Vladimir; O'Connor, Christopher M

2003-09-01

Platelets play a key role in the progression of acute coronary syndromes (ACS). Clinical depression alone is also associated with enhanced platelet activation. The purpose of this study was to compare concentrations of established biomarkers of enhanced platelet/endothelial activation in clinically depressed versus non-depressed patients enrolled in recent clinical trials for ACS. Two hundred and eighty-one baseline plasma samples from patients with acute myocardial infarction (ASSENT-2; n = 41), with ACS (PRONTO; n = 126) and with clinical depression plus previous acute coronary syndrome within 6 months (SADHART; n = 64), and from normal healthy controls (n = 50) were analyzed. Blood was drawn before applying any therapeutic strategies including interventions, thrombolytics, infusions, and selective serotonin re-uptake inhibitors. Platelet factor 4, beta-thromboglobulin, platelet/endothelial cell adhesion molecule-1, P-selectin, thromboxane, prostacyclin, vascular cell adhesion molecule-1, and E-selectin were measured by enzyme-linked immunosorbent assay by a single core laboratory. Patients with ACS exhibited a higher degree of platelet activation than controls independently of the presence of depression. Plasma levels of P-selectin, thromboxane, prostacyclin, and vascular cell adhesion molecule-1 were the highest in the acute myocardial infarction group when compared with ACS despite the presence or absence of clinical depression. Surprisingly, patients with ACS and depression exhibited the highest levels of platelet factor 4, beta-thromboglobulin, and platelet/endothelial cell adhesion molecule-1 when compared with myocardial infarction or angina patients without clinical depression. E-selectin plasma level was constantly elevated compared with controls but did not differ among the groups dependent on the incidence of depression. The depressed plus ACS group had higher plasma levels of all biomarkers compared with the non-depressed patients. Retrospective analysis of the data from several clinical trials reveals that clinical depression is associated with enhanced activation of platelet/endothelial biomarkers even above the level expected in ACS. These findings may contribute to the unfavorable outcome associated with clinical depression in patients with ACS.

Equilibrium electrodeformation of a spheroidal vesicle in an ac electric field

NASA Astrophysics Data System (ADS)

Nganguia, H.; Young, Y.-N.

2013-11-01

In this work, we develop a theoretical model to explain the equilibrium spheroidal deformation of a giant unilamellar vesicle (GUV) under an alternating (ac) electric field. Suspended in a leaky dielectric fluid, the vesicle membrane is modeled as a thin capacitive spheroidal shell. The equilibrium vesicle shape results from the balance between mechanical forces from the viscous fluid, the restoring elastic membrane forces, and the externally imposed electric forces. Our spheroidal model predicts a deformation-dependent transmembrane potential, and is able to capture large deformation of a vesicle under an electric field. A detailed comparison against both experiments and small-deformation (quasispherical) theory showed that the spheroidal model gives better agreement with experiments in terms of the dependence on fluid conductivity ratio, permittivity ratio, vesicle size, electric field strength, and frequency. The spheroidal model also allows for an asymptotic analysis on the crossover frequency where the equilibrium vesicle shape crosses over between prolate and oblate shapes. Comparisons show that the spheroidal model gives better agreement with experimental observations.

Transcranial Alternating Current Stimulation: A Potential Risk for Genetic Generalized Epilepsy Patients (Study Case)

PubMed Central

San-Juan, Daniel; Sarmiento, Carlos Ignacio; Hernandez-Ruiz, Axel; Elizondo-Zepeda, Ernesto; Santos-Vázquez, Gabriel; Reyes-Acevedo, Gerardo; Zúñiga-Gazcón, Héctor; Zamora-Jarquín, Carol Marina

2016-01-01

Transcranial alternating current stimulation (tACS) is a re-emergent neuromodulation technique that consists in the external application of oscillating electrical currents that induces changes in cortical excitability. We present the case of a 16-year-old female with pharmaco-resistant juvenile myoclonic epilepsy to 3 antiepileptic’s drugs characterized by 4 myoclonic and 20 absence seizures monthly. She received tACS at 1 mA at 3 Hz pulse train during 60 min over Fp1–Fp2 (10–20 EEG international system position) during 4 consecutive days using an Endeavor™ IOM Systems device® (Natus Medical Incorporated, Middleton, WI, USA). At the 1-month follow-up, she reported a 75% increase in seizures frequency (only myoclonic and tonic–clonic events) and developed a 24-h myoclonic status epilepticus that resolved with oral clonazepam and intravenous valproate. At the 2-month follow-up, the patient reported a 15-day seizure-free period. PMID:27965623

1987 Mosquito Identifications from USAF Installations in the Pacific Region

DTIC Science & Technology

1989-03-20

concentration); apply to shrubs, lower trees, and lawns chlorpyrifos (DursbanR) 44.4% EC, 0.8 - 1.6 fl oz/Ac propoxur (BaygonR) 13.9% EC, 8 fl oz/gal (1.1...finished concentration), apply to screens, doors, window frames, and other mosquito congregation surfaces. carbaryl (SevinR) 0.33 - 1.25 lb of 80

A randomized controlled, non-inferiority trial of modified natural versus artificial cycle for cryo-thawed embryo transfer.

PubMed

Groenewoud, E R; Cohlen, B J; Al-Oraiby, A; Brinkhuis, E A; Broekmans, F J M; de Bruin, J P; van den Dool, G; Fleisher, K; Friederich, J; Goddijn, M; Hoek, A; Hoozemans, D A; Kaaijk, E M; Koks, C A M; Laven, J S E; van der Linden, P J Q; Manger, A P; Slappendel, E; Spinder, T; Kollen, B J; Macklon, N S

2016-07-01

Are live birth rates (LBRs) after artificial cycle frozen-thawed embryo transfer (AC-FET) non-inferior to LBRs after modified natural cycle frozen-thawed embryo transfer (mNC-FET)? AC-FET is non-inferior to mNC-FET with regard to LBRs, clinical and ongoing pregnancy rates (OPRs) but AC-FET does result in higher cancellation rates. Pooling prior retrospective studies of AC-FET and mNC-FET results in comparable pregnancy and LBRs. However, these results have not yet been confirmed by a prospective randomized trial. In this non-inferiority prospective randomized controlled trial (acronym 'ANTARCTICA' trial), conducted from February 2009 to April 2014, 1032 patients were included of which 959 were available for analysis. The primary outcome of the study was live birth. Secondary outcomes were clinical and ongoing pregnancy, cycle cancellation and endometrium thickness. A cost-efficiency analysis was performed. This study was conducted in both secondary and tertiary fertility centres in the Netherlands. Patients included in this study had to be 18-40 years old, had to have a regular menstruation cycle between 26 and 35 days and frozen-thawed embryos to be transferred had to derive from one of the first three IVF or IVF-ICSI treatment cycles. Patients with a uterine anomaly, a contraindication for one of the prescribed medications in this study or patients undergoing a donor gamete procedure were excluded from participation. Patients were randomized based on a 1:1 allocation to either one cycle of mNC-FET or AC-FET. All embryos were cryopreserved using a slow-freeze technique. LBR after mNC-FET was 11.5% (57/495) versus 8.8% in AC-FET (41/464) resulting in an absolute difference in LBR of -0.027 in favour of mNC-FET (95% confidence interval (CI) -0.065-0.012; P = 0.171). Clinical pregnancy occurred in 94/495 (19.0%) patients in mNC-FET versus 75/464 (16.0%) patients in AC-FET (odds ratio (OR) 0.8, 95% CI 0.6-1.1, P = 0.25). 57/495 (11.5%) mNC-FET resulted in ongoing pregnancy versus 45/464 (9.6%) AC-FET (OR 0.7, 95% CI 0.5-1.1, P = 0.15). χ(2) test confirmed the lack of superiority. Significantly more cycles were cancelled in AC-FET (124/464 versus 101/495, OR 1.4, 95% CI 1.1-1.9, P = 0.02). The costs of each of the endometrial preparation methods were comparable (€617.50 per cycle in NC-FET versus €625.73 per cycle in AC-FET, P = 0.54). The minimum of 1150 patients required for adequate statistical power was not achieved. Moreover, LBRs were lower than anticipated in the sample size calculation. LBRs after AC-FET were not inferior to those achieved by mNC-FET. No significant differences in clinical and OPR were observed. The costs of both treatment approaches were comparable. An educational grant was received during the conduct of this study. Merck Sharpe Dohme had no influence on the design, execution and analyses of this study. E.R.G. received an education grant by Merck Sharpe Dohme (MSD) during the conduct of the present study. B.J.C. reports grants from MSD during the conduct of the study. A.H. reports grants from MSD and Ferring BV the Netherlands and personal fees from MSD. Grants from ZonMW, the Dutch Organization for Health Research and Development. J.S.E.L. reports grants from Ferring, MSD, Organon, Merck Serono and Schering-Plough during the conduct of the study. F.J.M.B. receives monetary compensation as member of the external advisory board for Merck Serono, consultancy work for Gedeon Richter, educational activities for Ferring BV, research cooperation with Ansh Labs and a strategic cooperation with Roche on automated anti Mullerian hormone assay development. N.S.M. reports receiving monetary compensations for external advisory and speaking work for Ferring BV, MSD, Anecova and Merck Serono during the conduct of the study. All reported competing interests are outside the submitted work. No other relationships or activities that could appear to have influenced the submitted work. Netherlands trial register, number NTR 1586. 13 January 2009. 20 April 2009. © The Author 2016. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A randomized controlled, non-inferiority trial of modified natural versus artificial cycle for cryo-thawed embryo transfer

PubMed Central

Groenewoud, E.R.; Cohlen, B.J.; Al-Oraiby, A.; Brinkhuis, E.A.; Broekmans, F.J.M.; de Bruin, J.P.; van den Dool, G.; Fleisher, K.; Friederich, J.; Goddijn, M.; Hoek, A.; Hoozemans, D.A.; Kaaijk, E.M.; Koks, C.A.M.; Laven, J.S.E.; van der Linden, P.J.Q.; Manger, A.P.; Slappendel, E.; Spinder, T.; Kollen, B.J.; Macklon, N.S.

2016-01-01

Abstract STUDY QUESTION Are live birth rates (LBRs) after artificial cycle frozen-thawed embryo transfer (AC-FET) non-inferior to LBRs after modified natural cycle frozen-thawed embryo transfer (mNC-FET)? SUMMARY ANSWER AC-FET is non-inferior to mNC-FET with regard to LBRs, clinical and ongoing pregnancy rates (OPRs) but AC-FET does result in higher cancellation rates. WHAT IS ALREADY KNOWN Pooling prior retrospective studies of AC-FET and mNC-FET results in comparable pregnancy and LBRs. However, these results have not yet been confirmed by a prospective randomized trial. STUDY DESIGN, SIZE AND DURATION In this non-inferiority prospective randomized controlled trial (acronym ‘ANTARCTICA’ trial), conducted from February 2009 to April 2014, 1032 patients were included of which 959 were available for analysis. The primary outcome of the study was live birth. Secondary outcomes were clinical and ongoing pregnancy, cycle cancellation and endometrium thickness. A cost-efficiency analysis was performed. PARTICIPANT/MATERIALS, SETTING, METHODS This study was conducted in both secondary and tertiary fertility centres in the Netherlands. Patients included in this study had to be 18–40 years old, had to have a regular menstruation cycle between 26 and 35 days and frozen-thawed embryos to be transferred had to derive from one of the first three IVF or IVF–ICSI treatment cycles. Patients with a uterine anomaly, a contraindication for one of the prescribed medications in this study or patients undergoing a donor gamete procedure were excluded from participation. Patients were randomized based on a 1:1 allocation to either one cycle of mNC-FET or AC-FET. All embryos were cryopreserved using a slow-freeze technique. MAIN RESULTS AND THE ROLE OF CHANCE LBR after mNC-FET was 11.5% (57/495) versus 8.8% in AC-FET (41/464) resulting in an absolute difference in LBR of −0.027 in favour of mNC-FET (95% confidence interval (CI) −0.065–0.012; P = 0.171). Clinical pregnancy occurred in 94/495 (19.0%) patients in mNC-FET versus 75/464 (16.0%) patients in AC-FET (odds ratio (OR) 0.8, 95% CI 0.6–1.1, P = 0.25). 57/495 (11.5%) mNC-FET resulted in ongoing pregnancy versus 45/464 (9.6%) AC-FET (OR 0.7, 95% CI 0.5–1.1, P = 0.15). χ2 test confirmed the lack of superiority. Significantly more cycles were cancelled in AC-FET (124/464 versus 101/495, OR 1.4, 95% CI 1.1–1.9, P = 0.02). The costs of each of the endometrial preparation methods were comparable (€617.50 per cycle in NC-FET versus €625.73 per cycle in AC-FET, P = 0.54). LIMITATIONS, REASONS FOR CAUTION The minimum of 1150 patients required for adequate statistical power was not achieved. Moreover, LBRs were lower than anticipated in the sample size calculation. WIDER IMPLICATIONS OF THE FINDINGS LBRs after AC-FET were not inferior to those achieved by mNC-FET. No significant differences in clinical and OPR were observed. The costs of both treatment approaches were comparable. STUDY FUNDING/COMPETING INTEREST(S) An educational grant was received during the conduct of this study. Merck Sharpe Dohme had no influence on the design, execution and analyses of this study. E.R.G. received an education grant by Merck Sharpe Dohme (MSD) during the conduct of the present study. B.J.C. reports grants from MSD during the conduct of the study. A.H. reports grants from MSD and Ferring BV the Netherlands and personal fees from MSD. Grants from ZonMW, the Dutch Organization for Health Research and Development. J.S.E.L. reports grants from Ferring, MSD, Organon, Merck Serono and Schering-Plough during the conduct of the study. F.J.M.B. receives monetary compensation as member of the external advisory board for Merck Serono, consultancy work for Gedeon Richter, educational activities for Ferring BV, research cooperation with Ansh Labs and a strategic cooperation with Roche on automated anti Mullerian hormone assay development. N.S.M. reports receiving monetary compensations for external advisory and speaking work for Ferring BV, MSD, Anecova and Merck Serono during the conduct of the study. All reported competing interests are outside the submitted work. No other relationships or activities that could appear to have influenced the submitted work. TRIAL REGISTRATION NUMBER Netherlands trial register, number NTR 1586. TRIAL REGISTRATION DATE 13 January 2009. FIRST PATIENT INCLUDED 20 April 2009. PMID:27179265

Categorization of fetal external findings in developmental toxicology studies by the Terminology Committee of the Japanese Teratology Society.

PubMed

Izumi, Yuko; Ooshima, Yojiro; Chihara, Kazuhiro; Fujiwara, Michio; Katsumata, Yoshihiro; Shiota, Kohei

2018-05-01

Categorization of fetal external findings in common laboratory animals, intended to make the agreement at Berlin Workshop in 2014 more practical, was proposed by the Terminology Committee of the Japanese Teratology Society at the Workshop in the 55th Japanese Teratology Society Annual Meeting in 2015. In the Workshop, 73 external findings, which had been categorized as "Gray zone" anomalies but not as "Malformation" or "Variation" in the 2014 Berlin Workshop, were discussed and classified as Malformation, "Non-structural abnormality," Variation, and "Not applicable." The proposal was based on the results of a survey conducted in 2014, where 20 facilities (including pharmaceutical, chemical, and pesticide companies and contract laboratories) and 2 selected expert teratologists in Japan were asked for their opinions on the categorization of these findings. Based on the discussion, Japanese Teratology Society members have agreed that 42 out of the 73 findings can be classified as Malformations (38), Non-structural abnormalities (3), Malformations/Non-structural abnormalities (1), and Variations (0), while the remaining 31 findings were recommended to be categorized as Not applicable for fetuses. The details of the classification are shown on the website of the Japanese Teratology Society (http://www.umin.ac.jp/cadb/External.pdf). © 2018 Japanese Teratology Society.

49 CFR 195.588 - What standards apply to direct assessment?

Code of Federal Regulations, 2011 CFR

2011-10-01

... TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.588 What standards apply to direct... corrosion, you must follow the requirements of this section for performing external corrosion direct... direct assessment process. (b) The requirements for performing external corrosion direct assessment are...

49 CFR 195.588 - What standards apply to direct assessment?

Code of Federal Regulations, 2014 CFR

2014-10-01

... TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.588 What standards apply to direct... corrosion, you must follow the requirements of this section for performing external corrosion direct... direct assessment process. (b) The requirements for performing external corrosion direct assessment are...

49 CFR 195.588 - What standards apply to direct assessment?

Code of Federal Regulations, 2012 CFR

2012-10-01

... TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.588 What standards apply to direct... corrosion, you must follow the requirements of this section for performing external corrosion direct... direct assessment process. (b) The requirements for performing external corrosion direct assessment are...

49 CFR 195.588 - What standards apply to direct assessment?

Code of Federal Regulations, 2013 CFR

2013-10-01

... TRANSPORTATION OF HAZARDOUS LIQUIDS BY PIPELINE Corrosion Control § 195.588 What standards apply to direct... corrosion, you must follow the requirements of this section for performing external corrosion direct... direct assessment process. (b) The requirements for performing external corrosion direct assessment are...

Nonlinear modeling of forced magnetic reconnection in slab geometry with NIMROD

NASA Astrophysics Data System (ADS)

Beidler, M. T.; Callen, J. D.; Hegna, C. C.; Sovinec, C. R.

2017-05-01

The nonlinear, extended-magnetohydrodynamic (MHD) code NIMROD is benchmarked with the theory of time-dependent forced magnetic reconnection induced by small resonant fields in slab geometry in the context of visco-resistive MHD modeling. Linear computations agree with time-asymptotic, linear theory of flow screening of externally applied fields. The inclusion of flow in nonlinear computations can result in mode penetration due to the balance between electromagnetic and viscous forces in the time-asymptotic state, which produces bifurcations from a high-slip state to a low-slip state as the external field is slowly increased. We reproduce mode penetration and unlocking transitions by employing time-dependent externally applied magnetic fields. Mode penetration and unlocking exhibit hysteresis and occur at different magnitudes of applied field. We also establish how nonlinearly determined flow screening of the resonant field is affected by the square of the magnitude of the externally applied field. These results emphasize that the inclusion of nonlinear physics is essential for accurate prediction of the reconnected field in a flowing plasma.

Study of the internal morphology of cation-exchange membranes by means of electroosmotic permeability relaxations.

PubMed

Barragán, V M; Izquierdo-Gil, M A; Godino, M P; Villaluenga, J P G

2009-10-01

The effect of an ac sinusoidal perturbation of known amplitude and frequency superimposed to the usual dc applied electric voltage difference on the electroosmotic flow through three cation-exchange membranes with different morphology has been studied. A dispersion of the electroosmotic permeability on the frequency of the applied ac signal has been found for the three membranes investigated, observing that the electroosmotic permeability reaches maximum values for some characteristic values of the frequency. These characteristic frequency values, which are related to relaxation processes in heterogeneous media, depend on the membrane system and permit to obtain information about the different structures of the membrane system. Thus, the study of the electroosmotic permeability relaxation can be used as a method to study the internal morphology of a cation-exchange membrane in a given electrolyte medium.

Impact of missing attenuation and scatter corrections on 99m Tc-MAA SPECT 3D dosimetry for liver radioembolization using the patient relative calibration methodology: A retrospective investigation on clinical images.

PubMed

Botta, Francesca; Ferrari, Mahila; Chiesa, Carlo; Vitali, Sara; Guerriero, Francesco; Nile, Maria Chiara De; Mira, Marta; Lorenzon, Leda; Pacilio, Massimiliano; Cremonesi, Marta

2018-04-01

To investigate the clinical implication of performing pre-treatment dosimetry for 90 Y-microspheres liver radioembolization on 99m Tc-MAA SPECT images reconstructed without attenuation or scatter correction and quantified with the patient relative calibration methodology. Twenty-five patients treated with SIR-Spheres ® at Istituto Europeo di Oncologia and 31 patients treated with TheraSphere ® at Istituto Nazionale Tumori were considered. For each acquired 99m Tc-MAA SPECT, four reconstructions were performed: with attenuation and scatter correction (AC_SC), only attenuation (AC_NoSC), only scatter (NoAC_SC) and without corrections (NoAC_NoSC). Absorbed dose maps were calculated from the activity maps, quantified applying the patient relative calibration to the SPECT images. Whole Liver (WL) and Tumor (T) regions were drawn on CT images. Injected Liver (IL) region was defined including the voxels receiving absorbed dose >3.8 Gy/GBq. Whole Healthy Liver (WHL) and Healthy Injected Liver (HIL) regions were obtained as WHL = WL - T and HIL = IL - T. Average absorbed dose to WHL and HIL were calculated, and the injection activity was derived following each Institute's procedure. The values obtained from AC_NoSC, NoAC_SC and NoAC_NoSC images were compared to the reference value suggested by AC_SC images using Bland-Altman analysis and Wilcoxon paired test (5% significance threshold). Absorbed-dose maps were compared to the reference map (AC_SC) in global terms using the Voxel Normalized Mean Square Error (%VNMSE), and at voxel level by calculating for each voxel the normalized difference with the reference value. The uncertainty affecting absorbed dose at voxel level was accounted for in the comparison; to this purpose, the voxel counts fluctuation due to Poisson and reconstruction noise was estimated from SPECT images of a water phantom acquired and reconstructed as patient images. NoAC_SC images lead to activity prescriptions not significantly different from the reference AC_SC images; the individual differences (<0.1 GBq for all IEO patients, <0.6 GBq for all but one INT patients) were comparable to the uncertainty affecting activity measurement. AC_NoSC and NoAC_NoSC images, instead, yielded significantly different activity prescriptions and wider 95% confidence intervals in the Bland-Altman analysis. Concerning the absorbed dose map, AC_NoSC images had the smallest %VNMSE value and the highest fraction of voxels differing less than 2 standard deviations from AC_SC. The patient relative calibration methodology can compensate for the missing attenuation correction when performing healthy liver pre-treatment dosimetry: safe treatments can be planned even on NoAC_SC images, suggesting activities comparable to AC_SC images. Scatter correction is recommended due to its heavy impact on healthy liver dosimetry. © 2018 American Association of Physicists in Medicine.

Studies on the Reduction of Intermodulation Generation in Communications Systems

DTIC Science & Technology

1980-07-07

AGENCY NAME & ADDRESS(ff dillfetmn from Controlling Office) IS. SECURITY CLASS. (of this report) Unclassified ISO . DECLASSIFICATION DOWNGRAD-ING SCHEDULE...FIELD 40GAUSS 120 GAUSS ISO GAUSS 340 GAUSS 1MG OSCILLOGRAMS OF 񓰨’ STAINLESS STEEL ADAPTER (SAMPLE A WITH EXTERNAL 2kHz AC MAGNETIC FIELD I PEAK...34P1 (,I P,2 -90- 7.07 GC; 0 V - iSo . .. _ 3D -100- AL(N23> ,-J/ -OLD/ / / OF-110 . O/ 070> V(HNS)// 2 -120 A(3080) , -i0.22 AL( NP) . / AG (H SI

Radiological Defense. Volume 4. An Introduction to Radiological Instruments for Military Use

DTIC Science & Technology

1950-01-01

alpha admission. Thin mica and stretched nylon walls with nonmetals of low atomic number and and rubber hydrochloride films about 5 microns writing...individual pulse. This process is called qu •,cIh1ng and can be ac- R, 5ME.OH, , • .. complished by using external electronic methods ’-""::_:-:Ž-:- " or...counter tubes field survey work. Mica windows down to 0.5 )resentliy employed in survey meters are " inch in mg/cm 2 are available, although in normal

ARC-1980-AC80-0107-8

NASA Image and Video Library

1980-02-06

ROCKWELL INTERNATIONAL TECHNICIANS MOUNT SOME OF THE NEARLY 8,000 CERAMIC-COATED TILES THAT REMAIN TO BE INSTALLED ON THE EXTERNAL SURFACES OF THE SPACE SHUTTLE ORBITER COLUMBIA TO COMPLETE THE THERMAL PROTECTION SYSTEM THAT WILL ABSORB THE INTENSE HEAT OF REENTERING THE EARTH'S ATMOSPHERE AFTER A MISSION IN SPACE. TILE INSTALLATION IS DONE ON AN AROUND-THE-CLOCK BASIS IN THE ORBITER PROCESSING FACILITY WHERE COLUMBIA, THE FIRST IN A NEW BREED OF MANNED, REUSABLE SPACECRAFT, IS BEING READIED FOR THE FIRST LAUNCH OF THE SPACE SHUTTLE LATER THIS YEAR.

ARC-1980-AC80-0107-9

NASA Image and Video Library

1980-02-06

ROCKWELL INTERNATIONAL TECHNICIANS MOUNT SOME OF THE NEARLY 8,000 CERAMIC-COATED TILES THAT REMAIN TO BE INSTALLED ON THE EXTERNAL SURFACES OF THE SPACE SHUTTLE ORBITER COLUMBIA TO COMPLETE THE THERMAL PROTECTION SYSTEM THAT WILL ABSORB THE INTENSE HEAT OF REENTERING THE EARTH'S ATMOSPHERE AFTER A MISSION IN SPACE. TILE INSTALLATION IS DONE ON AN AROUND-THE-CLOCK BASIS IN THE ORBITER PROCESSING FACILITY WHERE COLUMBIA, THE FIRST IN A NEW BREED OF MANNED, REUSABLE SPACECRAFT, IS BEING READIED FOR THE FIRST LAUNCH OF THE SPACE SHUTTLE LATER THIS YEAR.

Strain engineering of graphene nanoribbons: pseudomagnetic versus external magnetic fields

NASA Astrophysics Data System (ADS)

Prabhakar, Sanjay; Melnik, Roderick; Bonilla, Luis

2017-05-01

Bandgap opening due to strain engineering is a key architect for making graphene's optoelectronic, straintronic, and spintronic devices. We study the bandgap opening due to strain induced ripple waves and investigate the interplay between pseudomagnetic fields and externally applied magnetic fields on the band structures and spin relaxation in graphene nanoribbons (GNRs). We show that electron-hole bands of GNRs are highly influenced (i.e. level crossing of the bands are possible) by coupling two combined effects: pseudomagnetic fields (PMF) originating from strain tensor and external magnetic fields. In particular, we show that the tuning of the spin-splitting band extends to large externally applied magnetic fields with increasing values of pseudomagnetic fields. Level crossings of the bands in strained GNRs can also be observed due to the interplay between pseudomagnetic fields and externally applied magnetic fields. We also investigate the influence of this interplay on the electromagnetic field mediated spin relaxation mechanism in GNRs. In particular, we show that the spin hot spot can be observed at approximately B = 65 T (the externally applied magnetic field) and B0 = 53 T (the magnitude of induced pseudomagnetic field due to ripple waves) which may not be considered as an ideal location for the design of straintronic devices. Our analysis might be used for tuning the bandgaps in strained GNRs and utilized to design the optoelectronic devices for straintronic applications.

Heat transport in electrically aligned multiwalled carbon nanotubes dispersed in water

NASA Astrophysics Data System (ADS)

Cervantes-Alvarez, F.; Macias, J. D.; Alvarado-Gil, J. J.

2018-02-01

A modified Ångström method was used to determine the thermal diffusivity and thermal conductivity of aqueous dispersions of multiwalled carbon nanotubes as a function of their weight fraction concentration and in the presence of an externally applied electric field. Measurements were performed in planar samples, with a fixed thickness of 3.18 mm applying an AC voltage in the range from 0 to 70~V_RMS and for concentrations of carbon nanotubes from 0 to 2 wf%. It is shown that this field induces the formation of clusters followed by their alignment along the electric field, which can favor heat transfer in that direction. Heat transfer measurements show two regimes, in the first one under 0.5 wf%, voltages lower than 30~V_RMS are not strong enough to induce the adequate order of the carbon nanostructures, and as a consequence, thermal diffusivity of the dispersion remains close to the thermal diffusivity of water. In contrast for higher concentrations (above 1.5 wf%), 10~V_RMS are enough to get a good alignment. Above such thresholds of concentrations and voltages, thermal diffusivity and conductivity increase, when the electric field is increased, in such a way that for an applied voltage of 20~V_RMS and for a concentration of 1.5 wf%, an increase of 49% of the thermal conductivity was obtained. It is also shown that this approach exhibits limits, due to the fact that the electric-field induced structure, can act as a heating element at high electric field intensities and carbon nanotubes concentrations, which can induce convection and evaporation of the liquid matrix.

Near-microsecond human aquaporin 4 gating dynamics in static and alternating external electric fields: Non-equilibrium molecular dynamics

NASA Astrophysics Data System (ADS)

English, Niall J.; Garate, José-A.

2016-08-01

An extensive suite of non-equilibrium molecular-dynamics simulation has been performed for ˜0.85-0.9 μs of human aquaporin 4 in the absence and presence of externally applied static and alternating electric fields applied along the channels (in both axial directions in the static case, taken as the laboratory z-axis). These external fields were of 0.0065 V/Å (r.m.s.) intensity (of the same order as physiological electrical potentials); alternating fields ranged in frequency from 2.45 to 500 GHz. In-pore gating dynamics was studied, particularly of the relative propensities for "open" and "closed" states of the conserved arginines in the arginine/aromatic area (itself governed in no small part by external-field response of the dipolar alignment of the histidine-201 residue in the selectivity filter). In such a manner, the intimate connection of field-response governing "two-state" histidine states was established statistically and mechanistically. Given the appreciable size of the energy barriers for histidine-201 alignment, we have also performed non-equilibrium metadynamics/local-elevation of static fields applied along both directions to construct the free-energy landscape thereof in terms of external-field direction, elucidating the importance of field direction on energetics. We conclude from direct measurement of deterministic molecular dynamics in conjunction with applied-field metadynamics that the intrinsic electric field within the channel points along the +z-axis, such that externally applied static fields in this direction serve to "open" the channel in the selectivity-filter and the asparagine-proline-alanine region.

Near-microsecond human aquaporin 4 gating dynamics in static and alternating external electric fields: Non-equilibrium molecular dynamics.

PubMed

English, Niall J; Garate, José-A

2016-08-28

An extensive suite of non-equilibrium molecular-dynamics simulation has been performed for ∼0.85-0.9 μs of human aquaporin 4 in the absence and presence of externally applied static and alternating electric fields applied along the channels (in both axial directions in the static case, taken as the laboratory z-axis). These external fields were of 0.0065 V/Å (r.m.s.) intensity (of the same order as physiological electrical potentials); alternating fields ranged in frequency from 2.45 to 500 GHz. In-pore gating dynamics was studied, particularly of the relative propensities for "open" and "closed" states of the conserved arginines in the arginine/aromatic area (itself governed in no small part by external-field response of the dipolar alignment of the histidine-201 residue in the selectivity filter). In such a manner, the intimate connection of field-response governing "two-state" histidine states was established statistically and mechanistically. Given the appreciable size of the energy barriers for histidine-201 alignment, we have also performed non-equilibrium metadynamics/local-elevation of static fields applied along both directions to construct the free-energy landscape thereof in terms of external-field direction, elucidating the importance of field direction on energetics. We conclude from direct measurement of deterministic molecular dynamics in conjunction with applied-field metadynamics that the intrinsic electric field within the channel points along the +z-axis, such that externally applied static fields in this direction serve to "open" the channel in the selectivity-filter and the asparagine-proline-alanine region.

What Is the Best Treatment of Locally Advanced Nasopharyngeal Carcinoma? An Individual Patient Data Network Meta-Analysis

PubMed Central

Ribassin-Majed, Laureen; Marguet, Sophie; Lee, Anne W.M.; Ng, Wai Tong; Ma, Jun; Chan, Anthony T.C.; Huang, Pei-Yu; Zhu, Guopei; Chua, Daniel T.T.; Chen, Yong; Mai, Hai-Qiang; Kwong, Dora L.W.; Cheah, Shie-Lee; Moon, James; Tung, Yuk; Chi, Kwan-Hwa; Fountzilas, George; Bourhis, Jean; Pignon, Jean Pierre

2017-01-01

Purpose The role of adjuvant chemotherapy (AC) or induction chemotherapy (IC) in the treatment of locally advanced nasopharyngeal carcinoma is controversial. The individual patient data from the Meta-Analysis of Chemotherapy in Nasopharynx Carcinoma database were used to compare all available treatments. Methods All randomized trials of radiotherapy (RT) with or without chemotherapy in nonmetastatic nasopharyngeal carcinoma were considered. Overall, 20 trials and 5,144 patients were included. Treatments were grouped into seven categories: RT alone (RT), IC followed by RT (IC-RT), RT followed by AC (RT-AC), IC followed by RT followed by AC (IC-RT-AC), concomitant chemoradiotherapy (CRT), IC followed by CRT (IC-CRT), and CRT followed by AC (CRT-AC). P-score was used to rank the treatments. Fixed- and random-effects frequentist network meta-analysis models were applied. Results The three treatments with the highest probability of benefit on overall survival (OS) were CRT-AC, followed by CRT and IC-CRT, with respective hazard ratios (HRs [95% CIs]) compared with RT alone of 0.65 (0.56 to 0.75), 0.77 (0.64 to 0.92), and 0.81 (0.63 to 1.04). HRs (95% CIs) of CRT-AC compared with CRT for OS, progression-free survival (PFS), locoregional control, and distant control (DC) were, respectively, 0.85 (0.68 to 1.05), 0.81 (0.66 to 0.98), 0.70 (0.48 to 1.02), and 0.87 (0.61 to 1.25). IC-CRT ranked second for PFS and the best for DC. CRT never ranked first. HRs of CRT compared with IC-CRT for OS, PFS, locoregional control, and DC were, respectively, 0.95 (0.72 to 1.25), 1.13 (0.88 to 1.46), 1.05 (0.70 to 1.59), and 1.55 (0.94 to 2.56). Regimens with more chemotherapy were associated with increased risk of acute toxicity. Conclusion The addition of AC to CRT achieved the highest survival benefit and consistent improvement for all end points. The addition of IC to CRT achieved the highest effect on DC. PMID:27918720

Design and validation of a large-format transition edge sensor array magnetic shielding system for space application

NASA Astrophysics Data System (ADS)

Bergen, A.; van Weers, H. J.; Bruineman, C.; Dhallé, M. M. J.; Krooshoop, H. J. G.; ter Brake, H. J. M.; Ravensberg, K.; Jackson, B. D.; Wafelbakker, C. K.

2016-10-01

The paper describes the development and the experimental validation of a cryogenic magnetic shielding system for transition edge sensor based space detector arrays. The system consists of an outer mu-metal shield and an inner superconducting niobium shield. First, a basic comparison is made between thin-walled mu-metal and superconducting shields, giving an off-axis expression for the field inside a cup-shaped superconductor as a function of the transverse external field. Starting from these preliminary analytical considerations, the design of an adequate and realistic shielding configuration for future space flight applications (either X-IFU [D. Barret et al., e-print arXiv:1308.6784 [astro-ph.IM] (2013)] or SAFARI [B. Jackson et al., IEEE Trans. Terahertz Sci. Technol. 2, 12 (2012)]) is described in more detail. The numerical design and verification tools (static and dynamic finite element method (FEM) models) are discussed together with their required input, i.e., the magnetic-field dependent permeability data. Next, the actual manufacturing of the shields is described, including a method to create a superconducting joint between the two superconducting shield elements that avoid flux penetration through the seam. The final part of the paper presents the experimental verification of the model predictions and the validation of the shield's performance. The shields were cooled through the superconducting transition temperature of niobium in zero applied magnetic field (<10 nT) or in a DC field with magnitude ˜100 μT, applied either along the system's symmetry axis or perpendicular to it. After cool-down, DC trapped flux profiles were measured along the shield axis with a flux-gate magnetometer and the attenuation of externally applied AC fields (100 μT, 0.1 Hz, both axial and transverse) was verified along this axis with superconducting quantum interference device magnetometers. The system's measured on-axis shielding factor is greater than 106, well exceeding the requirement of the envisaged missions. Following field-cooling in an axial field of 85 μT, the residual internal DC field normal to the detector plane is less than 1 μT. The trapped field patterns are compared to the predictions of the dynamic FEM model, which describes them well in the region where the internal field exceeds 6 μT.

Design and validation of a large-format transition edge sensor array magnetic shielding system for space application.

PubMed

Bergen, A; van Weers, H J; Bruineman, C; Dhallé, M M J; Krooshoop, H J G; Ter Brake, H J M; Ravensberg, K; Jackson, B D; Wafelbakker, C K

2016-10-01

The paper describes the development and the experimental validation of a cryogenic magnetic shielding system for transition edge sensor based space detector arrays. The system consists of an outer mu-metal shield and an inner superconducting niobium shield. First, a basic comparison is made between thin-walled mu-metal and superconducting shields, giving an off-axis expression for the field inside a cup-shaped superconductor as a function of the transverse external field. Starting from these preliminary analytical considerations, the design of an adequate and realistic shielding configuration for future space flight applications (either X-IFU [D. Barret et al., e-print arXiv:1308.6784 [astro-ph.IM] (2013)] or SAFARI [B. Jackson et al., IEEE Trans. Terahertz Sci. Technol. 2, 12 (2012)]) is described in more detail. The numerical design and verification tools (static and dynamic finite element method (FEM) models) are discussed together with their required input, i.e., the magnetic-field dependent permeability data. Next, the actual manufacturing of the shields is described, including a method to create a superconducting joint between the two superconducting shield elements that avoid flux penetration through the seam. The final part of the paper presents the experimental verification of the model predictions and the validation of the shield's performance. The shields were cooled through the superconducting transition temperature of niobium in zero applied magnetic field (<10 nT) or in a DC field with magnitude ∼100 μT, applied either along the system's symmetry axis or perpendicular to it. After cool-down, DC trapped flux profiles were measured along the shield axis with a flux-gate magnetometer and the attenuation of externally applied AC fields (100 μT, 0.1 Hz, both axial and transverse) was verified along this axis with superconducting quantum interference device magnetometers. The system's measured on-axis shielding factor is greater than 10 6 , well exceeding the requirement of the envisaged missions. Following field-cooling in an axial field of 85 μT, the residual internal DC field normal to the detector plane is less than 1 μT. The trapped field patterns are compared to the predictions of the dynamic FEM model, which describes them well in the region where the internal field exceeds 6 μT.

21 CFR 82.2050 - General.

Code of Federal Regulations, 2010 CFR

2010-04-01

... PROVISIONALLY LISTED COLORS AND SPECIFICATIONS Externally Applied Drugs and Cosmetics § 82.2050 General. A batch of a straight color listed in this subpart may be certified, in accordance with the provisions of this part, for use in externally applied drugs and cosmetics, if such batch conforms to the...

Fluorescent coumarin-based probe for cysteine and homocysteine with live cell application

NASA Astrophysics Data System (ADS)

Wei, Ling-Fang; Thirumalaivasan, Natesan; Liao, Yu-Cheng; Wu, Shu-Pao

2017-08-01

Cysteine (Cys) and homocysteine (Hcy) are two of important biological thiols and function as important roles in several biological processes. The development of Cys and Hcy probes will help to explore the functions of biothiols in biological systems. In this work, a new coumarin-based probe AC, containing an acryloyl moiety, was developed for Cys and Hcy detection in cells. Cys and Hcy undergo a nucleophilic addition and subsequent cyclization reaction to remove to the acryloyl group and yield a fluorescent product, 7-hydroxylcomuarin. The probe AC showed good selectivity for cysteine and homocysteine over glutathione and other amino acids and had low detection limits of 65 nM for Cys and 79 nM for Hcy, respectively. Additionally, confocal imaging experiments demonstrated that the probe AC can be applied to visualize Cys and Hcy in living cells.

Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter.

PubMed

Gottardi, L; Adams, J; Bailey, C; Bandler, S; Bruijn, M; Chervenak, J; Eckart, M; Finkbeiner, F; den Hartog, R; Hoevers, H; Kelley, R; Kilbourne, C; de Korte, P; van der Kuur, J; Lindeman, M; Porter, F; Sadlier, J; Smith, S

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution Δ E FWHM =3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterised the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

Effect of molecule-particle binding on the reduction in the mixed-frequency alternating current magnetic susceptibility of magnetic bio-reagents

NASA Astrophysics Data System (ADS)

Yang, C. C.; Yang, S. Y.; Chen, H. H.; Weng, W. L.; Horng, H. E.; Chieh, J. J.; Hong, C. Y.; Yang, H. C.

2012-07-01

By specifically bio-functionalizing magnetic nanoparticles, magnetic nanoparticles are able to label target bio-molecules. This property can be applied to quantitatively detect molecules invitro by measuring the related magnetic signals of nanoparticles bound with target molecules. One of the magnetic signals is the reduction in the mixed-frequency ac magnetic susceptibility of suspended magnetic nanoparticles due to the molecule-particle association. Many experimental results show empirically that the molecular-concentration dependent reduction in ac magnetic susceptibility follows the logistic function. In this study, it has been demonstrated that the logistic behavior is originated from the growth of particle sizes due to the molecule-particle association. The analytic relationship between the growth of particle sizes and the reduction in ac magnetic susceptibility is developed.

Indoor Air Pollution in Non Ac Passenger Bus

NASA Astrophysics Data System (ADS)

El Husna, Iksiroh; Unzilatirrizqi, Rizal D. Yan El; Karyanto, Yudi; Sunoko, Henna R.

2018-02-01

Passenger buses have been one of favorite means of transportation in Indonesia due to its affordability and flexibility. Intensity of human activities during the trip in the buses have a potential of causing indoor air pollution (polusi udara dalam ruang; PUDR). The indoor air pollution has an impact of 1000-time bigger than outdoor air pollution (polusi udara luar ruang; PULR) on lung. This study aimed to find out indoor air pollution rate of non air conditioned buses using an approach to biological agent pollutant source. The study applied an analysis restricted to microorganisms persistence as one of the sources of the indoor air pollution. The media were placed in different parts of the non AC buses. This study revealed that fungs were found in the non AC buses. They became contaminants and developed pathogenic bacteria that caused air pollution.

Dynamics of vesicles in electric fields

NASA Astrophysics Data System (ADS)

Vlahovska, Petia; Gracia, Ruben

2007-11-01

Electromechanical forces are widely used for cell manipulation. Knowledge of the physical mechanisms underlying the interaction of cells and external fields is essential for practical applications. Vesicles are model cells made of a lipid bilayer membrane. They are examples of ``soft'' particles, i.e., their shape when subjected to flow or electric field is not given a priori but it is governed by the balance of membrane, fluid and electrical stresses. This generic ``softness'' gives rise to a very complex vesicle dynamics in external fields. In an AC electric field, as the frequency is increased, vesicles filled with a fluid less conducting than the surrounding fluid undergo shape transition from prolate to oblate ellipsoids. The opposite effect is observed with drops. We present an electro- hydrodynamic theory based on the leaky dielectric model that quantitatively describes experimental observations. We compare drops and vesicles, and show how their distinct behavior stems from different interfacial properties.

Parametric electroconvection in a weakly conducting fluid in a horizontal parallel-plate capacitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kartavykh, N. N.; Smorodin, B. L., E-mail: bsmorodin@yandex.ru; Il’in, V. A.

2015-07-15

We study the flows of a nonuniformly heated weakly conducting fluid in an ac electric field of a horizontal parallel-plate capacitor. Analysis is carried out for fluids in which the charge formation is governed by electroconductive mechanism associated with the temperature dependence of the electrical conductivity of the medium. Periodic and chaotic regimes of fluid flow are investigated in the limiting case of instantaneous charge relaxation and for a finite relaxation time. Bifurcation diagrams and electroconvective regimes charts are constructed. The regions where fluid oscillations synchronize with the frequency of the external field are determined. Hysteretic transitions between electroconvection regimesmore » are studied. The scenarios of transition to chaotic oscillations are analyzed. Depending on the natural frequency of electroconvective system and the external field frequency, the transition from periodic to chaotic oscillations can occur via quasiperiodicity, a subharmonic cascade, or intermittence.« less

AC signal characterization for optimization of a CMOS single-electron pump

NASA Astrophysics Data System (ADS)

Murray, Roy; Perron, Justin K.; Stewart, M. D., Jr.; Zimmerman, Neil M.

2018-02-01

Pumping single electrons at a set rate is being widely pursued as an electrical current standard. Semiconductor charge pumps have been pursued in a variety of modes, including single gate ratchet, a variety of 2-gate ratchet pumps, and 2-gate turnstiles. Whether pumping with one or two AC signals, lower error rates can result from better knowledge of the properties of the AC signal at the device. In this work, we operated a CMOS single-electron pump with a 2-gate ratchet style measurement and used the results to characterize and optimize our two AC signals. Fitting this data at various frequencies revealed both a difference in signal path length and attenuation between our two AC lines. Using this data, we corrected for the difference in signal path length and attenuation by applying an offset in both the phase and the amplitude at the signal generator. Operating the device as a turnstile while using the optimized parameters determined from the 2-gate ratchet measurement led to much flatter, more robust charge pumping plateaus. This method was useful in tuning our device up for optimal charge pumping, and may prove useful to the semiconductor quantum dot community to determine signal attenuation and path differences at the device.

Imaging and Selective Elimination of Glioblastoma Stem Cells with Theranostic Near-Infrared-Labeled CD133-Specific Antibodies.

PubMed

Jing, Hua; Weidensteiner, Claudia; Reichardt, Wilfried; Gaedicke, Simone; Zhu, Xuekai; Grosu, Anca-Ligia; Kobayashi, Hisataka; Niedermann, Gabriele

2016-01-01

Near-infrared photoimmunotherapy (NIR-PIT), which employs monoclonal antibody (mAb)-phototoxic phthalocyanine dye IR700 conjugates, permits the specific, image-guided and spatiotemporally controlled elimination of tumor cells. Here, we report the highly efficient NIR-PIT of human tumor xenografts initiated from patient-derived cancer stem cells (CSCs). Using glioblastoma stem cells (GBM-SCs) expressing the prototypic CSC marker AC133/CD133, we also demonstrate here for the first time that NIR-PIT is highly effective against brain tumors. The intravenously injected theranostic AC133 mAb conjugate enabled the non-invasive detection of orthotopic gliomas by NIR fluorescence imaging, and reached AC133+ GBM-SCs at the invasive tumor front. AC133-targeted NIR-PIT induced the rapid cell death of AC133+ GBM-SCs and thereby strong shrinkage of both subcutaneous and invasively growing brain tumors. A single round of NIR-PIT extended the overall survival of mice with established orthotopic gliomas by more than a factor of two, even though the harmless NIR light was applied through the intact skull. Humanised versions of this theranostic agent may facilitate intraoperative imaging and histopathological evaluation of tumor borders and enable the highly specific and efficient eradication of CSCs.

Low-Pressure Long-Term Xenon Storage for Electric Propulsion

NASA Technical Reports Server (NTRS)

Back, Dwight D.; Ramos, Charlie; Meyer, John A.

2001-01-01

This Phase 2 effort demonstrated an alternative Xe storage and regulation system using activated carbon (AC) as a secondary storage media (ACSFR). This regulator system is nonmechanical, simple, inexpensive, and lighter. The ACSFR system isolates the thruster from the compressed gas tank, and allows independent multiple setpoint thruster operation. The flow using an ACSFR can also be throttled by applying increments in electrical power. Primary storage of Xe by AC is not superior to compressed gas storage with regard to weight, but AC storage can provide volume reduction, lower pressures in space, and potentially in situ Xe purification. With partial fill designs, a primary AC storage vessel for Xe could also eliminate problems with two-phase storage and regulate pressure. AC could also be utilized in long-term large quantity storage of Xe serving as a compact capture site for boil-off. Several Xe delivery ACSFR protocols between 2 and 45 sccm, and 15 min to 7 hr, were tested with an average flow variance of 1.2 percent, average power requirements of 5 W, and repeatability s of about 0.4 percent. Power requirements are affected by ACSFR bed sizing and flow rate/ duration design points, and these flow variances can be reduced by optimizing PID controller parameters.

Exploring the mechanism how AF9 recognizes and binds H3K9ac by molecular dynamics simulations and free energy calculations.

PubMed

Wang, Quan; Zheng, Qing-Chuan; Zhang, Hong-Xing

2016-11-01

Histone acetylation is a very important regulatory mechanism in gene expression in the chromatin context. A new protein family-YEATS domains have been found as a novel histone acetylation reader, which could specific recognize the histone lysine acetylation. AF9 is an important one in the YEATS family. Focused on the AF9-H3K9ac (K9 acetylation) complex (ALY) (PDB code: 4TMP) and a serials of mutants, MUT (the acetyllsine of H3K9ac was mutated to lysine), F59A, G77A, and D103A, we applied molecular dynamics simulation and molecular mechanics Poisson-Boltzmann (MM-PBSA) free energy calculations to examine the role of AF9 protein in recognition interaction. The simulation results and analysis indicate that some residues of the protein have significant influence on recognition and binding to H3K9ac peptides and hydrophobic surface show the hydrophobic interactions play an important role in the binding. Our work can give important information to understand how the protein AF9 recognizes the peptides H3K9ac. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 779-786, 2016. © 2016 Wiley Periodicals, Inc.

Sensitivity Enhancement in Magnetic Sensors Based on Ferroelectric-Bimorphs and Multiferroic Composites

PubMed Central

Sreenivasulu, Gollapudi; Qu, Peng; Petrov, Vladimir; Qu, Hongwei; Srinivasan, Gopalan

2016-01-01

Multiferroic composites with ferromagnetic and ferroelectric phases have been studied in recent years for use as sensors of AC and DC magnetic fields. Their operation is based on magneto-electric (ME) coupling between the electric and magnetic subsystems and is mediated by mechanical strain. Such sensors for AC magnetic fields require a bias magnetic field to achieve pT-sensitivity. Novel magnetic sensors with a permanent magnet proof mass, either on a ferroelectric bimorph or a ferromagnetic-ferroelectric composite, are discussed. In both types, the interaction between the applied AC magnetic field and remnant magnetization of the magnet results in a mechanical strain and a voltage response in the ferroelectric. Our studies have been performed on sensors with a Nd-Fe-B permanent magnet proof mass on (i) a bimorph of oppositely-poled lead zirconate titanate (PZT) platelets and (ii) a layered multiferroic composite of PZT-Metglas-Ni. The sensors have been characterized in terms of sensitivity and equivalent magnetic noise N. Noise N in both type of sensors is on the order of 200 pT/√Hz at 1 Hz, a factor of 10 improvement compared to multiferroic sensors without a proof mass. When the AC magnetic field is applied at the bending resonance for the bimorph, the measured N ≈ 700 pT/√Hz. We discuss models based on magneto-electro-mechanical coupling at low frequency and bending resonance in the sensors and theoretical estimates of ME voltage coefficients are in very good agreement with the data. PMID:26907290

Using Automation to Improve the Flight Software Testing Process

NASA Technical Reports Server (NTRS)

ODonnell, James R., Jr.; Andrews, Stephen F.; Morgenstern, Wendy M.; Bartholomew, Maureen O.; McComas, David C.; Bauer, Frank H. (Technical Monitor)

2001-01-01

One of the critical phases in the development of a spacecraft attitude control system (ACS) is the testing of its flight software. The testing (and test verification) of ACS flight software requires a mix of skills involving software, attitude control, data manipulation, and analysis. The process of analyzing and verifying flight software test results often creates a bottleneck which dictates the speed at which flight software verification can be conducted. In the development of the Microwave Anisotropy Probe (MAP) spacecraft ACS subsystem, an integrated design environment was used that included a MAP high fidelity (HiFi) simulation, a central database of spacecraft parameters, a script language for numeric and string processing, and plotting capability. In this integrated environment, it was possible to automate many of the steps involved in flight software testing, making the entire process more efficient and thorough than on previous missions. In this paper, we will compare the testing process used on MAP to that used on previous missions. The software tools that were developed to automate testing and test verification will be discussed, including the ability to import and process test data, synchronize test data and automatically generate HiFi script files used for test verification, and an automated capability for generating comparison plots. A summary of the perceived benefits of applying these test methods on MAP will be given. Finally, the paper will conclude with a discussion of re-use of the tools and techniques presented, and the ongoing effort to apply them to flight software testing of the Triana spacecraft ACS subsystem.

Using Automation to Improve the Flight Software Testing Process

NASA Technical Reports Server (NTRS)

ODonnell, James R., Jr.; Morgenstern, Wendy M.; Bartholomew, Maureen O.

2001-01-01

One of the critical phases in the development of a spacecraft attitude control system (ACS) is the testing of its flight software. The testing (and test verification) of ACS flight software requires a mix of skills involving software, knowledge of attitude control, and attitude control hardware, data manipulation, and analysis. The process of analyzing and verifying flight software test results often creates a bottleneck which dictates the speed at which flight software verification can be conducted. In the development of the Microwave Anisotropy Probe (MAP) spacecraft ACS subsystem, an integrated design environment was used that included a MAP high fidelity (HiFi) simulation, a central database of spacecraft parameters, a script language for numeric and string processing, and plotting capability. In this integrated environment, it was possible to automate many of the steps involved in flight software testing, making the entire process more efficient and thorough than on previous missions. In this paper, we will compare the testing process used on MAP to that used on other missions. The software tools that were developed to automate testing and test verification will be discussed, including the ability to import and process test data, synchronize test data and automatically generate HiFi script files used for test verification, and an automated capability for generating comparison plots. A summary of the benefits of applying these test methods on MAP will be given. Finally, the paper will conclude with a discussion of re-use of the tools and techniques presented, and the ongoing effort to apply them to flight software testing of the Triana spacecraft ACS subsystem.

Comparative analyses of the neuron numbers and volumes of the amygdaloid complex in old and new world primates.

PubMed

Carlo, C N; Stefanacci, L; Semendeferi, K; Stevens, C F

2010-04-15

The amygdaloid complex (AC), a key component of the limbic system, is a brain region critical for the detection and interpretation of emotionally salient information. Therefore, changes in its structure and function are likely to provide correlates of mood and emotion disorders, diseases that afflict a large portion of the human population. Previous gross comparisons of the AC in control and diseased individuals have, however, mainly failed to discover these expected correlations with diseases. We have characterized AC nuclei in different nonhuman primate species to establish a baseline for more refined comparisons between the normal and the diseased amygdala. AC nuclei volume and neuron number in 19 subdivisions are reported from 13 Old and New World primate brains, spanning five primate species, and compared with corresponding data from humans. Analysis of the four largest AC nuclei revealed that volume and neuron number of one component, the central nucleus, has a negative allometric relationship with total amygdala volume and neuron number, which is in contrast with the isometric relationship found in the other AC nuclei (for both neuron number and volume). Neuron density decreases across all four nuclei according to a single power law with an exponent of about minus one-half. Because we have included quantitative comparisons with great apes and humans, our conclusions apply to human brains, and our scaling laws can potentially be used to study the anatomical correlates of the amygdala in disorders involving pathological emotion processing. (c) 2009 Wiley-Liss, Inc.

Ultrasound-assisted oxidation of dibenzothiophene with phosphotungstic acid supported on activated carbon.

PubMed

Liu, Liyan; Zhang, Yu; Tan, Wei

2014-05-01

Phosphotungstic acid (HPW) supported on activated carbon (AC) was applied to catalyze deep oxidation desulfurization of fuel oil with the assist of ultrasound. The sulfur-conversion rate was evaluated by measuring the concentration of dibenzothiophene (DBT) in n-octane before and after the oxidation. Supporting HPW on AC has been verified to play a positive role in UAOD process by a series of contrast tests, where only HPW, AC or a mixture of free HPW and AC was used. The influences of catalyst dose, ultrasound power, reaction temperature, H2O2:oil volume ratio and the reuse of catalyst on the catalytic oxidation desulfurization kinetics were investigated. The DBT conversion rate of the reaction catalyzed by supported HPW under ultrasound irradiation was higher than the summation of the reactions with HPW only and AC only as catalyst. With the increase of loading amount of HPW on AC, ultrasound power, H2O2:oil volume ratio and reaction temperature, the catalytic oxidation reactivity of DBT would be enhanced. The optimum loading amount of HPW was 10%, exceed which DBT conversion would no longer increase obviously. DBT could be completely converted under the optimized conditions (volume ratio of H2O2 to model oil: 1:10, mass ratio of the supported HPW to model oil: 1.25%, temperature: 70°C) after 9 min of ultrasound irradiation. Copyright © 2013 Elsevier B.V. All rights reserved.

Green Synthesis and Catalytic Activity of Gold Nanoparticles Synthesized by Artemisia capillaris Water Extract

NASA Astrophysics Data System (ADS)

Lim, Soo Hyeon; Ahn, Eun-Young; Park, Youmie

2016-10-01

Gold nanoparticles were synthesized using a water extract of Artemisia capillaris (AC-AuNPs) under different extract concentrations, and their catalytic activity was evaluated in a 4-nitrophenol reduction reaction in the presence of sodium borohydride. The AC-AuNPs showed violet or wine colors with characteristic surface plasmon resonance bands at 534 543 nm that were dependent on the extract concentration. Spherical nanoparticles with an average size of 16.88 ± 5.47 29.93 ± 9.80 nm were observed by transmission electron microscopy. A blue shift in the maximum surface plasmon resonance was observed with increasing extract concentration. The face-centered cubic structure of AC-AuNPs was confirmed by high-resolution X-ray diffraction analysis. Based on phytochemical screening and Fourier transform infrared spectra, flavonoids, phenolic compounds, and amino acids present in the extract contributed to the reduction of Au ions to AC-AuNPs. The average size of the AC-AuNPs decreased as the extract concentration during the synthesis was increased. Higher 4-nitrophenol reduction reaction rate constants were observed for smaller sizes. The extract in the AC-AuNPs was removed by centrifugation to investigate the effect of the extract in the reduction reaction. Interestingly, the removal of extracts greatly enhanced their catalytic activity by up to 50.4 %. The proposed experimental method, which uses simple centrifugation, can be applied to other metallic nanoparticles that are green synthesized with plant extracts to enhance their catalytic activity.

Enhanced cell trapping throughput using DC-biased AC electric field in a dielectrophoresis-based fluidic device with densely packed silica beads.

PubMed

Lewpiriyawong, Nuttawut; Xu, Guolin; Yang, Chun

2018-03-01

This paper presents the use of DC-biased AC electric field for enhancing cell trapping throughput in an insulator-based dielectrophoretic (iDEP) fluidic device with densely packed silica beads. Cell suspension is carried through the iDEP device by a pressure-driven flow. Under an applied DC-biased AC electric field, DEP trapping force is produced as a result of non-uniform electric field induced by the gap of electrically insulating silica beads packed between two mesh electrodes that allow both fluid and cells to pass through. While the AC component is mainly to control the magnitude of DEP trapping force, the DC component generates local electroosmotic (EO) flow in the cavity between the beads and the EO flow can be set to move along or against the main pressure-driven flow. Our experimental and simulation results show that desirable trapping is achieved when the EO flow direction is along (not against) the main flow direction. Using our proposed DC-biased AC field, the device can enhance the trapping throughput (in terms of the flowrate of cell suspension) up to five times while yielding almost the same cell capture rates as compared to the pure AC field case. Additionally, the device was demonstrated to selectively trap dead yeast cells from a mixture of flowing live and dead yeast cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Large amplitude Fourier transformed ac voltammetry at a rotating disc electrode: a versatile technique for covering Levich and flow rate insensitive regimes in a single experiment.

PubMed

Bano, Kiran; Kennedy, Gareth F; Zhang, Jie; Bond, Alan M

2012-04-14

The theory for large amplitude Fourier transformed ac voltammetry at a rotating disc electrode is described. Resolution of time domain data into dc and ac harmonic components reveals that the mass transport for the dc component is controlled by convective-diffusion, while the background free higher order harmonic components are flow rate insensitive and mainly governed by linear diffusion. Thus, remarkable versatility is available; Levich behaviour of the dc component limiting current provides diffusion coefficient values and access to higher harmonics allows fast electrode kinetics to be probed. Two series of experiments (dc and ac voltammetry) have been required to extract these parameters; here large amplitude ac voltammetry with RDE methodology is used to demonstrate that kinetics and diffusion coefficient information can be extracted from a single experiment. To demonstrate the power of this approach, theoretical and experimental comparisons of data obtained for the reversible [Ru(NH(3))(6)](3+/2+) and quasi-reversible [Fe(CN)(6)](3-/4-) electron transfer processes are presented over a wide range of electrode rotation rates and with different concentrations and electrode materials. Excellent agreement of experimental and simulated data is achieved, which allows parameters such as electron transfer rate, diffusion coefficient, uncompensated resistance and others to be determined using a strategically applied approach that takes into account the different levels of sensitivity of each parameter to the dc or the ac harmonic.

Limitations of temperature measurement in the aural canal with an ear mould integrated sensor.

PubMed

Teunissen, L P J; de Haan, A; de Koning, J J; Clairbois, H E; Daanen, H A M

2011-09-01

Aural canal temperature measurement using an ear mould integrated sensor (T(ac)) might be a method suited for continuous non-invasive core temperature estimation in operational settings. We studied the effect of ambient temperature, wind and high intensity exercise on T(ac) and its ability to predict esophageal (T(es)) and rectal temperatures (T(re)). Seven subjects performed a protocol of rest at 21, 10 and 30 °C, followed by exercise and recovery at 30 °C. The subjects performed the protocol twice: with and without face-wind from halfway through the 30 °C rest period. Extra auricle insulation was applied at one side. Ambient temperature changes affected T(ac) significantly, while T(es) and T(re) remained stable. Insulating the auricle reduced but did not abolish this effect. Wind had an immediate cooling effect on T(ac) independent of auricle insulation. During exercise and recovery in 30 °C, T(ac) provided acceptable group predictions of T(re) in trials without wind (bias: -0.66 ± 0.21 °C covered, -1.20 ± 0.15 °C uncovered). Bias was considerably higher with wind, but variability was similar (-1.73 ± 0.11 °C covered, -2.49 ± 0.04 °C uncovered). Individual predictions of T(es) and T(re) showed more variation, especially with wind. We conclude that T(ac) may be used for core temperature assessment of groups in warm and stable conditions.

In situ surface transfer process of Cry1Ac protein on SiO2： The effect of biosurfactants for desorption.

PubMed

Miao, Shuzhou; Yuan, Xingzhong; Liang, Yunshan; Wang, Hou; Leng, Lijian; Wu, Zhibin; Jiang, Longbo; Li, Yifu; Mo, Dan; Zeng, Guangming

2018-01-05

Genetically modified Bacillus thuringiensis (Bt) crops, which have been widely used in agricultural transgenic plants, express insecticidal Cry proteins and release the toxin into soils. Taking into consideration the environmental risk of Cry proteins, biosurfactant-rhamnolipids were applied to desorb Cry proteins from soil environment, which has not been elucidated before. Quartz crystal microbalance with dissipation (QCM-D) was used in this article to investigate the adsorption and desorption behaviors of Cry1Ac on SiO 2 surface (model soil). Results showed that patch-controlled electrostatic attraction (PCEA) governed Cry1Ac adsorption to SiO 2, and the solution pH or ionic strength can affect PCEA. The adsorption kinetics could be fitted by the pseudo-second-order model, and the adsorption isotherm was fitted to Langmuir model with correlation coefficients higher than 0.999. The desorption characteristics of Cry1Ac from SiO 2 were assessed in the presence of mono-rhamnolipid, di-rhamnolipid or complex-rhamnolipid. Mono-rhamnolipid exhibited the most significant positive effect on desorption performance. With a complete removal of Cry1Ac reached when mono-rhamnolipid concentration was up to 50mgL -1 . Additionally, the desorption was enhanced at alkaline pH range, and Cry1Ac can be completely and rapidly desorbed by rhamnolipids from SiO 2 at ionic strength of 5×10 -2 M. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis and Control of Pulse-Width Modulated AC to DC Voltage Source Converters.

NASA Astrophysics Data System (ADS)

Wu, Rusong

The pulse width modulated AC to DC voltage source converter is comprehensively analyzed in the thesis. A general mathematical model of the converter is first established, which is discontinuous, time-variant and non-linear. The following three techniques are used to obtain closed form solutions: Fourier analysis, transformation of reference frame and small signal linearization. Three models, namely, a steady-state DC model, a low frequency small signal AC model and a high frequency model, are consequently developed. Finally, three solution sets, namely, the steady-state solution, various dynamic transfer functions and the high frequency harmonic components, are obtained from the three models. Two control strategies, the Phase and Amplitude Control (PAC) and a new proposed strategy, Predicted Current Control with a Fixed Switching Frequency (PCFF), are investigated. Based on the transfer functions derived from the above mentioned analysis, regulators for a closed-loop control are designed. A prototype circuit is built to experimentally verify the theoretical predictions. The analysis and experimental results show that both strategies produce nearly sinusoidal line current with unity power factor on the utility side in both rectifying and regenerating operations and concurrently provide a regulated DC output voltage on the load side. However the proposed PCFF control has a faster and improved dynamic response over the PAC control. Moreover it is also easier to be implemented. Therefore, the PCFF control is preferable to the PAC control. As an example of application, a configuration of variable DC supply under PCFF control is proposed. The quasi-optimal dynamic response obtained shows that the PWM AC to DC converter lays the foundation for building a four-quadrant, fast-dynamic system, and the PCFF control is an effective strategy for improving dynamic performances not only as applied to the AC to DC converter, but also as applied to the DC to DC chopper or other circuits.

AC electric field induced dipole-based on-chip 3D cell rotation.

PubMed

Benhal, Prateek; Chase, J Geoffrey; Gaynor, Paul; Oback, Björn; Wang, Wenhui

2014-08-07

The precise rotation of suspended cells is one of the many fundamental manipulations used in a wide range of biotechnological applications such as cell injection and enucleation in nuclear transfer (NT) cloning. Noticeably scarce among the existing rotation techniques is the three-dimensional (3D) rotation of cells on a single chip. Here we present an alternating current (ac) induced electric field-based biochip platform, which has an open-top sub-mm square chamber enclosed by four sidewall electrodes and two bottom electrodes, to achieve rotation about the two axes, thus 3D cell rotation. By applying an ac potential to the four sidewall electrodes, an in-plane (yaw) rotating electric field is generated and in-plane rotation is achieved. Similarly, by applying an ac potential to two opposite sidewall electrodes and the two bottom electrodes, an out-of-plane (pitch) rotating electric field is generated and rolling rotation is achieved. As a prompt proof-of-concept, bottom electrodes were constructed with transparent indium tin oxide (ITO) using the standard lift-off process and the sidewall electrodes were constructed using a low-cost micro-milling process and then assembled to form the chip. Through experiments, we demonstrate rotation of bovine oocytes of ~120 μm diameter about two axes, with the capability of controlling the rotation direction and the rate for each axis through control of the ac potential amplitude, frequency, and phase shift, and cell medium conductivity. The maximum observed rotation rate reached nearly 140° s⁻¹, while a consistent rotation rate reached up to 40° s⁻¹. Rotation rate spectra for zona pellucida-intact and zona pellucida-free oocytes were further compared and found to have no effective difference. This simple, transparent, cheap-to-manufacture, and open-top platform allows additional functional modules to be integrated to become a more powerful cell manipulation system.

DC response of dust to low frequency AC signals

NASA Astrophysics Data System (ADS)

McKinlay, Michael; Konopka, Uwe; Thomas, Edward

2017-10-01

Macroscopic changes in the shape and equilibrium position of clouds of charged microparticles suspended in a plasma have been observed in response to low frequency AC signals. In these experiments, dusty plasmas consisting of 2-micron diameter silica microspheres suspended between an anode and cathode in an argon, DC glow discharge plasma are produced in a grounded, 6-way cross vacuum chamber. An AC signal, produced by a function generator and amplified by a bipolar op-amp, is superimposed onto the potential from the cathode. The frequencies of the applied AC signals, ranging from tens to hundreds of kHz, are comparable to the ion-neutral collision frequency; well below the ion/electron plasma frequencies, but also considerably higher than the dust plasma frequency. This presentation will detail the experimental setup, present documentation and categorization of observations of the dust response, and present an initial model of the response. This work is supported by funding from the US Dept. of Energy, Grant Number DE-SC0016330, and by the National Science Foundation, Grant Number PHY-1613087.

Ratchet Effects, Negative Mobility, and Phase Locking for Skyrmions on Periodic Substrates

NASA Astrophysics Data System (ADS)

Reichhardt, Charles; Ray, Dipanjan; Olson Reichhardt, Cynthia

We examine the dynamics of skyrmions interacting with 1D and 2D periodic substrates in the presence of dc and ac drives. We find that the Magnus term strongly affects the skyrmion dynamics and that new kinds of phenomena can occur which are absent for overdamped ac and dc driven particles interacting with similar substrates. We show that it is possible to realize a Magnus induced ratchet for skyrmions interacting with an asymmetric potential, where the application of an ac drive can produce quantized dc motion of the skyrmions even when the ac force is perpendicular to the substrate asymmetry direction. For symmetric substrates it is also possible to achieve a negative mobility effect where the net skyrmion motion runs counter to an applied dc drive. Here, as a function of increasing dc drive, the velocity-force curves show a series of locking phases that have different features from the classic Shapiro steps found in overdamped systems. In the phase locking and ratcheting states, the skyrmions undergo intricate 2D orbits induced by the Magnus term.

Development of a glottal area index that integrates glottal gap size and open quotient

PubMed Central

Chen, Gang; Kreiman, Jody; Gerratt, Bruce R.; Neubauer, Juergen; Shue, Yen-Liang; Alwan, Abeer

2013-01-01

Because voice signals result from vocal fold vibration, perceptually meaningful vibratory measures should quantify those aspects of vibration that correspond to differences in voice quality. In this study, glottal area waveforms were extracted from high-speed videoendoscopy of the vocal folds. Principal component analysis was applied to these waveforms to investigate the factors that vary with voice quality. Results showed that the first principal component derived from tokens without glottal gaps was significantly (p < 0.01) associated with the open quotient (OQ). The alternating-current (AC) measure had a significant effect (p < 0.01) on the first principal component among tokens exhibiting glottal gaps. A measure AC/OQ, defined as the ratio of AC to OQ, was proposed to combine both amplitude and temporal characteristics of the glottal area waveform for both complete and incomplete glottal closures. Analyses of “glide” phonations in which quality varied continuously from breathy to pressed showed that the AC/OQ measure was able to characterize the corresponding continuum of glottal area waveform variation, regardless of the presence or absence of glottal gaps. PMID:23464035

Alternating current loss characteristics in (bismuth,lead)SCCO and yttrium barium copper oxide superconducting tapes

NASA Astrophysics Data System (ADS)

Nguyen, Doan Ngoc

Alternating current (AC) loss and current carrying capacity are two of the most crucial considerations in large-scale power applications of high temperature superconducting (HTS) conductors. AC losses result in an increased thermal load for cooling machines, and thus increased operating costs. Furthermore, AC losses can stimulate quenching phenomena or at least decrease the stability margin for superconducting devices. Thus, understanding AC losses is essential for the development of HTS AC applications. The main focus of this dissertation is to make reliable total AC loss measurements and interpret the experimental results in a theoretical framework. With a specially designed magnet, advanced total AC loss measurement system in liquid nitrogen (77 K) has been successfully built. Both calorimetric and electromagnetic methods were employed to confirm the validity of the measured results and to have a more thorough understanding of AC loss in HTS conductors. The measurement is capable of measuring total AC loss in HTS tapes over a wide range of frequency and amplitude of transport current and magnetic field. An accurate phase control technique allows measurement of total AC loss with any phase difference between the transport current and magnetic field by calorimetric method. In addition, a novel total AC loss measurement system with variable temperatures from 30 K to 100 K was successfully built and tested. Understanding the dependence of AC losses on temperature will enable optimization of the operating temperature and design of HTS devices. As a part of the dissertation, numerical calculations using Brandt's model were developed to study electrodynamics and total AC loss in HTS conductors. In the calculations, the superconducting electrical behavior is assumed to follow a power-law model. In general, the practical properties of conductors, including field-dependence of critical current density Jc, n-value and non-uniform distribution of Jc, can be accounted for in the numerical calculations. The numerical calculations are also capable of investigating eddy current loss in the stabilizer and ferromagnetic loss in the substrate of YBa2Cu3O 7-delta (YBCO) coated conductor. AC loss characteristics and electrodynamics in several (Bi,Pb)2 Sr2Ca2Cu3Ox (Bi-2223) and YBCO tapes were studied experimentally and numerically. It was found that AC loss behavior Ax in HTS tapes is strongly affected by the sample parameters such as cross-section, structure, dimensions, critical current distribution as well as by operation parameters including temperature, frequency, the phase difference between transport current and magnetic field, the orientation of magnetic field. The Ni-5%W substrate in YBCO conductors generates some ferromagnetic loss but this loss component is significantly reduced by a small parallel DC magnetic field. At a given AC magnetic field B0, there is a temperature Tmax at which the magnetization loss is maximum. The design of HTS devices needs to be optimized to avoid operating at that temperature. In general, the total AC loss in HTS tapes is still high for many power device applications, especially for those that present a rather high AC applied magnetic field. The development of low loss conductors is therefore crucial for HTS large-scale applications.

Modeling the Effects of Trait Diversity on Short-term Adaptive Capacity and Long-term Productivity of Phytoplankton Communities

NASA Astrophysics Data System (ADS)

Smith, S. L.; Vallina, S. M.; Merico, A.

2016-02-01

We examine Biodiversity and Ecosystem Function (BEF) in a model phytoplankton community, using two recently developed mechanisms for sustaining diversity. The Trait Diffusion (TD) formulation represents the maintenance of diversity via endogenous mechanisms, such as inter-generational trait plasticity and rapid evolution. The 'Kill-the-Winner' (KTW) formulation for grazing sustains prey biodiversity via the exogenous mechanism of active prey switching. We implement both TD and KTW in a continuous trait-distribution model using simplified size-scalings to define a gleaner-opportunist trade-off for a phytoplankton community. By simulating semi-continuous culture experiments with periodic external dilutions, we test the dynamic response of the phytoplankton community to different scenarios of pulsed nutrient supply. We quantify the short-term Adaptive Capacity (AC) of the community by the specific growth rate averaged over the first 3 days of perturbations, and the Long-term Productivity (LP) by its average over the entire 120 day period of perturbations. When either the frequency or intensity of pulses is low, both AC and LP tend to decrease with diversity (and vice versa). Trait diversity has more impact on AC, particularly for pulses of high frequency or intensity, for which it tends to increase gradually at first, then steeply, and then to saturate with increasing diversity. For pulses of moderate intensity and frequency, increasing trait diversity from low to moderate levels leads to a trade-off between enhancing AC while slightly decreasing LP. Ultimately, we find that sustaining diversity increases the speed at which the phytoplankton community changes its composition in terms of size and hence nutrient acquisition traits, which may have implications for the transfer of productivity through the foodweb.

Converting an AEG Cyclotron to H- Acceleration and Extraction

NASA Astrophysics Data System (ADS)

Ramsey, Fred; Carroll, Lewis; Rathmann, Tom; Huenges, Ernst; Bechtold, Matthias Mentler Volker

2009-03-01

Clinical Trials are under way to evaluate agents labeled with the nuclide 225Ac and its decay product 213Bi, in targeted alpha-immuno-therapy [1]. 225Ac can be produced on a medium-energy cyclotron via the nuclear reaction 226Ra(p,n)225Ac. To demonstrate proof-of-principle, a vintage AEG cyclotron, Model E33 [2], with an internal target, had been employed in a pilot production program at the Technical University of Munich (TUM). To enhance production capability and further support the clinical studies, the TUM facility has recently been refurbished and upgraded, adding a new external beam-line, automated target irradiation and transport systems, new laboratories, hot cells, etc. [3]. An improved high-power rotating target has been built and installed [4]. The AEG cyclotron itself has also been modified and upgraded to accelerate and extract H- ions. We have designed, built, and tested a new axial Penning-type ion source which is optimized for the production of H- ions. The ion source has continued to evolve through experiment and experience. Steady improvements in materials and mechanics have led to enhanced source stability, life-time, and H- production. We have also designed and built a precision H- charge-exchange beam-extraction system which is equipped with a vacuum lock. To fit within the tight mechanical constraint imposed by the narrow magnet gap, the system incorporates a novel chain-drive foil holder and foil-changer mechanism. The reconfigured cyclotron system has now been in operation for more than 1 year. Three long-duration target irradiations have been conducted. The most recent bombardment ran 160 continuous hours at a beam on target of ˜80 microamperes for a total yield of ˜70 milli-curies of 225Ac.

Nitric oxide leads to cytoskeletal reorganization in the retinal pigment epithelium under oxidative stress.

PubMed

Sripathi, Srinivas R; He, Weilue; Um, Ji-Yeon; Moser, Trevor; Dehnbostel, Stevie; Kindt, Kimberly; Goldman, Jeremy; Frost, Megan C; Jahng, Wan Jin

2012-01-01

Light is a risk factor for various eye diseases, including age-related macular degeneration (AMD) and retinitis pigmentosa (RP). We aim to understand how cytoskeletal proteins in the retinal pigment epithetlium (RPE) respond to oxidative stress, including light and how these responses affect apoptotic signaling. Previously, proteomic analysis revealed that the expression levels of vimentin and serine/threonine protein phosphatase 2A (PP2A) are significantly increased when mice are exposed under continuous light for 7 days compared to a condition of 12 hrs light/dark cycling exposure using retina degeneration 1 (rd1) model. When melatonin is administered to animals while they are exposed to continuous light, the levels of vimentin and PP2A return to a normal level. Vimentin is a substrate of PP2A that directly binds to vimentin and dephosphorylates it. The current study shows that upregulation of PP2Ac (catalytic subunit) phosphorylation negatively correlates with vimentin phosphorylation under stress condition. Stabilization of vimentin appears to be achieved by decreased PP2Ac phosphorylation by nitric oxide induction. We tested our hypothesis that site-specific modifications of PP2Ac may drive cytoskeletal reorganization by vimentin dephosphorylation through nitric oxide signaling. We speculate that nitric oxide determines protein nitration under stress conditions. Our results demonstrate that PP2A and vimentin are modulated by nitric oxide as a key element involved in cytoskeletal signaling. The current study suggests that external stress enhances nitric oxide to regulate PP2Ac and vimentin phosphorylation, thereby stabilizing or destabilizing vimentin. Phosphorylation may result in depolymerization of vimentin, leading to nonfilamentous particle formation. We propose that a stabilized vimentin might act as an anti-apoptotic molecule when cells are under oxidative stress.

Nitric oxide leads to cytoskeletal reorganization in the retinal pigment epithelium under oxidative stress

PubMed Central

Um, Ji-Yeon; Moser, Trevor; Dehnbostel, Stevie; Kindt, Kimberly; Goldman, Jeremy; Frost, Megan C.; Jahng, Wan Jin

2016-01-01

Light is a risk factor for various eye diseases, including age-related macular degeneration (AMD) and retinitis pigmentosa (RP). We aim to understand how cytoskeletal proteins in the retinal pigment epithetlium (RPE) respond to oxidative stress, including light and how these responses affect apoptotic signaling. Previously, proteomic analysis revealed that the expression levels of vimentin and serine/threonine protein phosphatase 2A (PP2A) are significantly increased when mice are exposed under continuous light for 7 days compared to a condition of 12 hrs light/dark cycling exposure using retina degeneration 1 (rd1) model. When melatonin is administered to animals while they are exposed to continuous light, the levels of vimentin and PP2A return to a normal level. Vimentin is a substrate of PP2A that directly binds to vimentin and dephosphorylates it. The current study shows that upregulation of PP2Ac (catalytic subunit) phosphorylation negatively correlates with vimentin phosphorylation under stress condition. Stabilization of vimentin appears to be achieved by decreased PP2Ac phosphorylation by nitric oxide induction. We tested our hypothesis that site-specific modifications of PP2Ac may drive cytoskeletal reorganization by vimentin dephosphorylation through nitric oxide signaling. We speculate that nitric oxide determines protein nitration under stress conditions. Our results demonstrate that PP2A and vimentin are modulated by nitric oxide as a key element involved in cytoskeletal signaling. The current study suggests that external stress enhances nitric oxide to regulate PP2Ac and vimentin phosphorylation, thereby stabilizing or destabilizing vimentin. Phosphorylation may result in depolymerization of vimentin, leading to nonfilamentous particle formation. We propose that a stabilized vimentin might act as an anti-apoptotic molecule when cells are under oxidative stress. PMID:27974994

Applying spatio-temporal models to assess variations across health care areas and regions: Lessons from the decentralized Spanish National Health System.

PubMed

Librero, Julián; Ibañez, Berta; Martínez-Lizaga, Natalia; Peiró, Salvador; Bernal-Delgado, Enrique

2017-01-01

To illustrate the ability of hierarchical Bayesian spatio-temporal models in capturing different geo-temporal structures in order to explain hospital risk variations using three different conditions: Percutaneous Coronary Intervention (PCI), Colectomy in Colorectal Cancer (CCC) and Chronic Obstructive Pulmonary Disease (COPD). This is an observational population-based spatio-temporal study, from 2002 to 2013, with a two-level geographical structure, Autonomous Communities (AC) and Health Care Areas (HA). The Spanish National Health System, a quasi-federal structure with 17 regional governments (AC) with full responsibility in planning and financing, and 203 HA providing hospital and primary care to a defined population. A poisson-log normal mixed model in the Bayesian framework was fitted using the INLA efficient estimation procedure. The spatio-temporal hospitalization relative risks, the evolution of their variation, and the relative contribution (fraction of variation) of each of the model components (AC, HA, year and interaction AC-year). Following PCI-CCC-CODP order, the three conditions show differences in the initial hospitalization rates (from 4 to 21 per 10,000 person-years) and in their trends (upward, inverted V shape, downward). Most of the risk variation is captured by phenomena occurring at the HA level (fraction variance: 51.6, 54.7 and 56.9%). At AC level, the risk of PCI hospitalization follow a heterogeneous ascending dynamic (interaction AC-year: 17.7%), whereas in COPD the AC role is more homogenous and important (37%). In a system where the decisions loci are differentiated, the spatio-temporal modeling allows to assess the dynamic relative role of different levels of decision and their influence on health outcomes.

Non-invasive Brain Stimulation: A Paradigm Shift in Understanding Brain Oscillations.

PubMed

Vosskuhl, Johannes; Strüber, Daniel; Herrmann, Christoph S

2018-01-01

Cognitive neuroscience set out to understand the neural mechanisms underlying cognition. One central question is how oscillatory brain activity relates to cognitive processes. Up to now, most of the evidence supporting this relationship was correlative in nature. This situation changed dramatically with the recent development of non-invasive brain stimulation (NIBS) techniques, which open up new vistas for neuroscience by allowing researchers for the first time to validate their correlational theories by manipulating brain functioning directly. In this review, we focus on transcranial alternating current stimulation (tACS), an electrical brain stimulation method that applies sinusoidal currents to the intact scalp of human individuals to directly interfere with ongoing brain oscillations. We outline how tACS can impact human brain oscillations by employing different levels of observation from non-invasive tACS application in healthy volunteers and intracranial recordings in patients to animal studies demonstrating the effectiveness of alternating electric fields on neurons in vitro and in vivo . These findings likely translate to humans as comparable effects can be observed in human and animal studies. Neural entrainment and plasticity are suggested to mediate the behavioral effects of tACS. Furthermore, we focus on mechanistic theories about the relationship between certain cognitive functions and specific parameters of brain oscillaitons such as its amplitude, frequency, phase and phase coherence. For each of these parameters we present the current state of testing its functional relevance by means of tACS. Recent developments in the field of tACS are outlined which include the stimulation with physiologically inspired non-sinusoidal waveforms, stimulation protocols which allow for the observation of online-effects, and closed loop applications of tACS.

Spatiotemporal relationship of embryonic cholinesterases with cell proliferation in chicken brain and eye.

PubMed Central

Layer, P G; Sporns, O

1987-01-01

Close relationships between acetylcholinesterase (AcChoEase; acetylcholine acetylhydrolase, true cholinesterase, EC, 3.1.1.7) and butyrylcholinesterase (BtChoEase, acylcholine acylhydrolase, pseudocholinesterase, EC, 3.1.1.8) with cell proliferation were observed in the early chicken brain. These include the following: BtChoEase is transiently accumulating in patchy fashion on the ventricular side of the neuroepithelium shortly before AcChoEase appears in cell bodies along the opposing mantle layer. The amount of BtChoEase in retina and brain is greatest in the early phase (E3-E5, or incubation periods of 3-5 days); in retina it decreases about 2 days later than in brain. However, AcChoEase expression increases with time, in inverse order to that of BtChoEase. In both tissues decrease of cell proliferation is closely followed by decrease in BtChoEase. A double-labeling technique of cholinesterase staining together with [3H]thymidine autoradiography reveals proliferation zones that are diffusely stained by BtChoEase but not by AcChoEase. Patches intensely stained for BtChoEase accompany clusters of cells in final stages of mitosis on their way to the differentiation zone, where they begin expressing AcChoEase. By applying different thymidine pulses, we identify an 11-hr lag from the last thymidine-uptake to full AcChoEase expression. (iv) These findings are confirmed by studying lens development, where areas of proliferation and differentiation are well separated. The spatiotemporal pattern of the transition of neuroblasts from a proliferating into a differentiating state correlates with the expression of BtChoEase just before and during mitosis and that of AcChoEase about 11 hr after mitosis. Thus cholinesterases could be involved in the regulation of this transition. Images PMID:3467355

Effect of tibial positioning on the diagnosis of posterolateral rotatory instability in the posterior cruciate ligament-deficient knee.

PubMed

Strauss, Eric J; Ishak, Charbel; Inzerillo, Christopher; Walsh, Michael; Yildirim, Gokce; Walker, Peter; Jazrawi, Laith; Rosen, Jeffrey

2007-08-01

To determine whether positioning of the tibia affects the degree of tibial external rotation seen during a dial test in the posterior cruciate ligament (PCL)-posterolateral corner (PLC)-deficient knee. Laboratory investigation. Biomechanics laboratory. An anterior force applied to the tibia in the combined PCL-PLC-deficient knee will yield increased tibial external rotation during a dial test. The degree of tibial external rotation was measured with 5 Nm of external rotation torque applied to the tibia at both 30 degrees and 90 degrees of knee flexion. Before the torque was applied, an anterior force, a posterior force, or neutral (normal, reduced control) force was applied to the tibia. External rotation measurements were repeated after sequential sectioning of the PCL, the posterolateral structures and the fibular collateral ligament (FCL). Baseline testing of the intact specimens demonstrated a mean external rotation of 18.6 degrees with the knee flexed to 30 degrees (range 16.1-21.0 degrees ), and a mean external rotation of 17.3 degrees with the knee flexed to 90 degrees (range 13.8-20.0 degrees ). Sequential sectioning of the PCL, popliteus and popliteofibular ligament, and the FCL led to a significant increase in tibial external rotation compared with the intact knee for all testing scenarios. After sectioning of the popliteus and popliteofibular ligament, the application of an anterior force during testing led to a mean tibial external rotation that was 5 degrees greater than during testing in the neutral position and 7.5 degrees greater than during testing with a posterior force. In the PCL, popliteus/popliteofibular ligament and FCL-deficient knee, external rotation was 9 degrees and 12 degrees greater with the application of an anterior force during testing compared with neutral positioning and the application of a posterior force, respectively. An anterior force applied to the tibia during the dial test in a combined PCL-PLC-injured knee increased the overall amount of observed tibial external rotation during the dial test. The anterior force reduced the posterior tibial subluxation associated with PCL injury, which is analogous to what is observed when the dial test is performed with the patient in the prone position. Reducing the tibia with either an anterior force when the patient is supine or performing the dial test with the patient in the prone position increases the ability of an examiner to detect a concomitant PLC injury in the setting of a PCL-deficient knee.

Internal and external potential-field estimation from regional vector data at varying satellite altitude

NASA Astrophysics Data System (ADS)

Plattner, Alain; Simons, Frederik J.

2017-10-01

When modelling satellite data to recover a global planetary magnetic or gravitational potential field, the method of choice remains their analysis in terms of spherical harmonics. When only regional data are available, or when data quality varies strongly with geographic location, the inversion problem becomes severely ill-posed. In those cases, adopting explicitly local methods is to be preferred over adapting global ones (e.g. by regularization). Here, we develop the theory behind a procedure to invert for planetary potential fields from vector observations collected within a spatially bounded region at varying satellite altitude. Our method relies on the construction of spatiospectrally localized bases of functions that mitigate the noise amplification caused by downward continuation (from the satellite altitude to the source) while balancing the conflicting demands for spatial concentration and spectral limitation. The `altitude-cognizant' gradient vector Slepian functions (AC-GVSF) enjoy a noise tolerance under downward continuation that is much improved relative to the `classical' gradient vector Slepian functions (CL-GVSF), which do not factor satellite altitude into their construction. Furthermore, venturing beyond the realm of their first application, published in a preceding paper, in the present article we extend the theory to being able to handle both internal and external potential-field estimation. Solving simultaneously for internal and external fields under the limitation of regional data availability reduces internal-field artefacts introduced by downward-continuing unmodelled external fields, as we show with numerical examples. We explain our solution strategies on the basis of analytic expressions for the behaviour of the estimation bias and variance of models for which signal and noise are uncorrelated, (essentially) space- and band-limited, and spectrally (almost) white. The AC-GVSF are optimal linear combinations of vector spherical harmonics. Their construction is not altogether very computationally demanding when the concentration domains (the regions of spatial concentration) have circular symmetry, for example, on spherical caps or rings—even when the spherical-harmonic bandwidth is large. Data inversion proceeds by solving for the expansion coefficients of truncated function sequences, by least-squares analysis in a reduced-dimensional space. Hence, our method brings high-resolution regional potential-field modelling from incomplete and noisy vector-valued satellite data within reach of contemporary desktop machines.

Closed Loop Fuzzy Logic Controlled PV Based Cascaded Boost Five-Level Inverter System

NASA Astrophysics Data System (ADS)

Revana, Guruswamy; Kota, Venkata Reddy

2018-04-01

Recent developments in intelligent control methods and power electronics have produced PV based DC to AC converters related to AC drives. Cascaded boost converter and inverter find their way in interconnecting PV and Induction Motor. This paper deals with digital simulation and implementation of closed loop controlled five-level inverter based Photo-Voltaic (PV) system. The objective of this work is to reduce the harmonics using Multi Level Inverter based system. The DC output from the PV panel is boosted using cascaded-boost-converters. The DC output of these cascaded boost converters is applied to the bridges of the cascaded inverter. The AC output voltage is obtained by the series cascading of the output voltage of the two inverters. The investigations are done with Induction motor load. Cascaded boost-converter is proposed in the present work to produce the required DC Voltage at the input of the bridge inverter. A simple FLC is applied to CBFLIIM system. The FLC is proposed to reduce the steady state error. The simulation results are compared with the hardware results. The results of the comparison are made to show the improvement in dynamic response in terms of settling time and steady state error. Design procedure and control strategy are presented in detail.

AC Electroosmotic Pumping in Nanofluidic Funnels.

PubMed

Kneller, Andrew R; Haywood, Daniel G; Jacobson, Stephen C

2016-06-21

We report efficient pumping of fluids through nanofluidic funnels when a symmetric AC waveform is applied. The asymmetric geometry of the nanofluidic funnel induces not only ion current rectification but also electroosmotic flow rectification. In the base-to-tip direction, the funnel exhibits a lower ion conductance and a higher electroosmotic flow velocity, whereas, in the tip-to-base direction, the funnel has a higher ion conductance and a lower electroosmotic flow velocity. Consequently, symmetric AC waveforms easily pump fluid through the nanofunnels over a range of frequencies, e.g., 5 Hz to 5 kHz. In our experiments, the nanofunnels were milled into glass substrates with a focused ion beam (FIB) instrument, and the funnel design had a constant 5° taper with aspect ratios (funnel tip width to funnel depth) of 0.1 to 1.0. We tracked ion current rectification by current-voltage (I-V) response and electroosmotic flow rectification by transport of a zwitterionic fluorescent probe. Rectification of ion current and electroosmotic flow increased with increasing electric field applied to the nanofunnel. Our results support three-dimensional simulations of ion transport and electroosmotic transport through nanofunnels, which suggest the asymmetric electroosmotic transport stems from an induced pressure at the junction of the nanochannel and nanofunnel tip.

Phase-sensitive techniques applied to a micromachined vacuum sensor

NASA Astrophysics Data System (ADS)

Chapman, Glenn H.; Sawadsky, N.; Juneja, P. P.

1996-09-01

Phase sensitive AC measurement techniques are particularly applicable to micromachined sensors detecting temperature changes at a sensor caused by a microheater. The small mass produces rapid thermal response to AC signals which are easily detectable with lock-in amplifiers. Phase sensitive measurements were applied to a CMOS compatible micromachined pressure sensor consisting a polysilicon sense line, 760 microns long, on an oxide microbridge separated by 6 microns on each horizontal side from similar polysilicon heaters, all over a micromachined cavity. Sinusoidal heater signals at 32 Hz induced temperature caused sense line resistance changes at 64 Hz. The lock-in detected this as a first harmonic sense resistor voltage from a DC constant sense current. By observing the first harmonic the lock-in rejects all AC coupling of noise by capacitance or inductance, by measuring only those signals at the 64 Hz frequency and with a fixed phase relationship to the heater driver signals. This sensor produces large signals near atmospheric pressure, declining to 7 (mu) V below 0.1 mTorr. Phase measurements between 760 and 100 Torr where the air's thermal conductivity changes little, combined with amplitude changes at low pressure generate a pressure measurement accurate at 5 percent from 760 Torr to 10 mTorr, sensing of induced temperature changes of 0.001 degree C.

Closed Loop Fuzzy Logic Controlled PV Based Cascaded Boost Five-Level Inverter System

NASA Astrophysics Data System (ADS)

Revana, Guruswamy; Kota, Venkata Reddy

2017-12-01

Recent developments in intelligent control methods and power electronics have produced PV based DC to AC converters related to AC drives. Cascaded boost converter and inverter find their way in interconnecting PV and Induction Motor. This paper deals with digital simulation and implementation of closed loop controlled five-level inverter based Photo-Voltaic (PV) system. The objective of this work is to reduce the harmonics using Multi Level Inverter based system. The DC output from the PV panel is boosted using cascaded-boost-converters. The DC output of these cascaded boost converters is applied to the bridges of the cascaded inverter. The AC output voltage is obtained by the series cascading of the output voltage of the two inverters. The investigations are done with Induction motor load. Cascaded boost-converter is proposed in the present work to produce the required DC Voltage at the input of the bridge inverter. A simple FLC is applied to CBFLIIM system. The FLC is proposed to reduce the steady state error. The simulation results are compared with the hardware results. The results of the comparison are made to show the improvement in dynamic response in terms of settling time and steady state error. Design procedure and control strategy are presented in detail.

Efficacy of ε-polylysine, lauric arginate, or acidic calcium sulfate applied sequentially for Salmonella reduction on membrane filters and chicken carcasses.

PubMed

Benli, Hakan; Sanchez-Plata, Marcos X; Keeton, Jimmy T

2011-05-01

Salmonella contamination continues to be one of the major concerns for the microbiological safety of raw poultry products. Application of more than one decontamination agent as a multihurdle intervention to carcasses in a processing line might produce greater reductions than one treatment alone due to different modes of action of individual antimicrobials. In this study, all possible two-way combinations and individual applications of ε-polylysine (EPL), lauric arginate (LAE), and acidic calcium sulfate (ACS) solutions were evaluated for their effects against Salmonella enterica serovars, including Enteritidis and Typhimurium, using a sterile membrane filter model system. The combinations that provided higher Salmonella reductions were further evaluated on inoculated chicken carcasses in various concentrations applied in a sequential manner. Sequential spray applications of 300 mg of EPL per liter followed by 30% ACS and of 200 mg of LAE per liter followed by 30% ACS produced the highest Salmonella reductions on inoculated chicken carcasses, by 2.1 and 2.2 log CFU/ml, respectively. Our results indicated that these sequential spray applications of decontamination agents are effective for decreasing Salmonella contamination on poultry carcasses, but further studies are needed to determine the effectiveness of these combinations over a storage period.

Ag nanoparticle-filled TiO2 nanotube arrays prepared by anodization and electrophoretic deposition for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Wei, Xing; Sugri Nbelayim, Pascal; Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

2017-03-01

A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anodic oxidation from Ti metal foil. Surface charged Ag nanoparticles (NPs) are prepared by chemical reduction. After a pretreatment of the TNT arrays by acetone vapor, Ag NP filled TNT arrays can be achieved by electrophoretic deposition (EPD). Effects of the applied voltage during EPD such as DC-AC difference, frequency and waveform are investigated by quantitative analysis using atomic absorption spectroscopy. The results show that the best EPD condition is using DC 2 V + AC 4 V and a square wave of 1 Hz as the applied voltage. Back illuminated dye-sensitized solar cells are fabricated from TNT arrays with and without Ag NPs. The efficiency increased from 3.70% to 5.01% by the deposition of Ag NPs.

Electrokinetic Aggregation of Colloidal Particles on Electrodes

NASA Astrophysics Data System (ADS)

Anderson, John L.; Solomentsev, Yuri E.; Guelcher, Scott A.

1999-11-01

Colloidal particles deposited on an electrode have been observed to attract each other and form clusters in the presence of an applied electric field. This aggregation is important to the formation of dense monolayer films during electrophoretic depositon processes. Under dc fields two particles attract each other over a length scale comparable to the particle size, and the velocity of approach between two particles is proportional to the applied electric field and the particles' zeta potential. We have developed a theory for particle aggregation based on electroosmotic flow about each deposited particle. Experimental results for the relative motion of two particles are in good quantitative agreement with the theory. Our recent experiments with ac fields also show attraction between particles that is roughly proportional to the rms electric field but inversely proportional to the frequency. We discuss here a model based on electrokinetic processes that can account for some of the observations in ac fields.

Tailoring particle translocation via dielectrophoresis in pore channels

PubMed Central

Tanaka, Shoji; Tsutsui, Makusu; Theodore, Hu; Yuhui, He; Arima, Akihide; Tsuji, Tetsuro; Doi, Kentaro; Kawano, Satoyuki; Taniguchi, Masateru; Kawai, Tomoji

2016-01-01

Understanding and controlling electrophoretic motions of nanoscopic objects in fluidic channels are a central challenge in developing nanopore technology for molecular analyses. Although progress has been made in slowing the translocation velocity to meet the requirement for electrical detections of analytes via picoampere current measurements, there exists no method useful for regulating particle flows in the transverse directions. Here, we report the use of dielectrophoresis to manipulate the single-particle passage through a solid-state pore. We created a trap field by applying AC voltage between electrodes embedded in a low-aspect-ratio micropore. We demonstrated a traffic control of particles to go through center or near side surface via the voltage frequency. We also found enhanced capture efficiency along with faster escaping speed of particles by virtue of the AC-mediated electroosmosis. This method is compatible with nanopore sensing and would be widely applied for reducing off-axis effects to achieve single-molecule identification. PMID:27527126

A concise evidence-based physical examination for diagnosis of acromioclavicular joint pathology: a systematic review.

PubMed

Krill, Michael K; Rosas, Samuel; Kwon, KiHyun; Dakkak, Andrew; Nwachukwu, Benedict U; McCormick, Frank

2018-02-01

The clinical examination of the shoulder joint is an undervalued diagnostic tool for evaluating acromioclavicular (AC) joint pathology. Applying evidence-based clinical tests enables providers to make an accurate diagnosis and minimize costly imaging procedures and potential delays in care. The purpose of this study was to create a decision tree analysis enabling simple and accurate diagnosis of AC joint pathology. A systematic review of the Medline, Ovid and Cochrane Review databases was performed to identify level one and two diagnostic studies evaluating clinical tests for AC joint pathology. Individual test characteristics were combined in series and in parallel to improve sensitivities and specificities. A secondary analysis utilized subjective pre-test probabilities to create a clinical decision tree algorithm with post-test probabilities. The optimal special test combination to screen and confirm AC joint pathology combined Paxinos sign and O'Brien's Test, with a specificity of 95.8% when performed in series; whereas, Paxinos sign and Hawkins-Kennedy Test demonstrated a sensitivity of 93.7% when performed in parallel. Paxinos sign and O'Brien's Test demonstrated the greatest positive likelihood ratio (2.71); whereas, Paxinos sign and Hawkins-Kennedy Test reported the lowest negative likelihood ratio (0.35). No combination of special tests performed in series or in parallel creates more than a small impact on post-test probabilities to screen or confirm AC joint pathology. Paxinos sign and O'Brien's Test is the only special test combination that has a small and sometimes important impact when used both in series and in parallel. Physical examination testing is not beneficial for diagnosis of AC joint pathology when pretest probability is unequivocal. In these instances, it is of benefit to proceed with procedural tests to evaluate AC joint pathology. Ultrasound-guided corticosteroid injections are diagnostic and therapeutic. An ultrasound-guided AC joint corticosteroid injection may be an appropriate new standard for treatment and surgical decision-making. II - Systematic Review.

Evaluation of rhBMP-2/collagen/TCP-HA bone graft with and without bone marrow cells in the canine femoral multi defect model.

PubMed

Luangphakdy, V; Shinohara, K; Pan, H; Boehm, C; Samaranska, A; Muschler, G F

2015-01-12

Recombinant human bone morphogenetic protein-2, when applied to an absorbable type 1 bovine collagen sponge (rhBMP-2/ACS) is an effective therapy in many bone grafting settings. Bone marrow aspirate (BMA) has also been used as a source of transplantable osteogenic connective tissue progenitors. This study was designed to characterize the performance of a scaffold comprising rhBMP-2/ACS in which the sponge wraps around tri-calcium phosphate hydroxyapatite granules (rhBMP-2/ACS/TCP-HA) and to test the hypothesis that addition of BMA will improve the performance of this construct in the Canine Femoral Multi Defect Model. In each subject, two sites were grafted with rhBMP-2/ACS/TCP-HA scaffold loaded with BMA clot and two other sites with rhBMP-2/ACS/TCP-HA scaffold loaded with wound blood (WB). After correction for unresorbed TCP-HA granules, sites grafted with rhBMP-2/ACS/TCP-HA+BMA and rhBMP-2/ACS/TCP-HA+WB were similar, with mean percent bone volumes of 10.9 %±1.2 and 11.2 %±1.2, respectively. No differences were seen in quantitative histomorphometry. While bone formation using both constructs was robust, this study did not support the hypothesis that the addition of unprocessed bone marrow aspirate clot improved bone regeneration in a site engrafted with rhBMP-2/ACS/TCP-HA+BMA. In contrast to prior studies using this model, new bone formation was greater at the center of the defect where TCP-HA was distributed. This finding suggests a potential synergy between rhBMP-2 and the centrally placed ceramic and cellular components of the graft construct. Further optimization may also require more uniform distribution of TCP-HA, alternative cell delivery strategies, and a more rigorous large animal segmental defect model.

Studying of crystal growth and overall crystallization of naproxen from binary mixtures.

PubMed

Kaminska, E; Madejczyk, O; Tarnacka, M; Jurkiewicz, K; Kaminski, K; Paluch, M

2017-04-01

Broadband dielectric spectroscopy (BDS) and differential scanning calorimetry (DSC) were applied to investigate the molecular dynamics and phase transitions in binary mixtures composed of naproxen (NAP) and acetylated saccharides: maltose (acMAL) and sucrose (acSUC). Moreover, the application of BDS method and optical microscopy enabled us to study both crystallization kinetics and crystal growth of naproxen from the solid dispersions with the highest content of modified carbohydrates (1:5wt ratio). It was found that the activation barriers of crystallization estimated from dielectric measurements are completely different for both studied herein mixtures. Much higher E a (=205kJ/mol) was obtained for NAP-acMAL solid dispersion. It is probably due to simultaneous crystallization of both components of the mixture. On the other hand, lower value of E a in the case of NAP-acSUC solid dispersion (81kJ/mol) indicated, that naproxen is the only crystallizing compound. This hypothesis was confirmed by X-ray diffraction studies. We also suggested that specific intermolecular dipole-dipole interactions between active substance and excipient may be an alternative explanation for the difference between activation barrier obtained for NAP-acMAL and NAP-acSUC binary mixtures. Furthermore, optical measurements showed that the activation energy for crystal growth of naproxen increases in binary mixtures. They also revealed that both excipients: acMAL and acSUC move the temperature of the maximum of crystal growth towards lower temperatures. Interestingly, this maximum occurs for nearly the same structural relaxation time, which is a good approximation of viscosity, for all samples. Finally, it was also noticed that although naproxen crystallizes to the same polymorphic form in both systems, there are some differences in morphology of obtained crystals. Thus, the observed behavior may have a significant impact on the bioavailability and dissolution rate of API produced in that way. Copyright © 2016 Elsevier B.V. All rights reserved.