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Sample records for affect dielectric membrane

  1. Investigation of the dielectric properties of nanofiltration membranes

    OpenAIRE

    Oatley, Darren Lee; Llenas Argelaguet, Laia; Aljohani, Nasser H M; Williams, Paul Melvyn; Martínez Lladó, Xavier; Rovira Boixaderas, Miquel; Pablo Ribas, Joan de

    2013-01-01

    Membrane nanofiltration is extremely complex and is dependent on the micro-hydrodynamics and interfacial events occurring at the membrane surface and within the membrane nanopores. There is significant debate as to the exact nature of these complex phenomena and rejection is typically attributed to a combination of steric and electrical effects. The electrical effects are less well understood and in particular the contribution of dielectric exclusion. There is a real need to determine a suita...

  2. Modifications of the Dielectric Properties of Biological Membranes by Heating

    CERN Document Server

    Savescu, S B

    2004-01-01

    Biological cell suspensions are known to show dielectric dispersions due to the Maxwell-Wagner mechanism. Many examples are summarized in a number of papers by Schwan [7, 9, 10]. By the application of an appropriate analysis to the dielectric dispersion, it is possible to estimate electrical phase parameters related to protoplasm and cell membrane. A dielectric theory of interfacial polarization for a suspension of conducting particles (protoplasm) covered with poorly conducting shells (plasma membrane) was developed by Pauly and Schwan [7], and was satisfactory applied for low volume fractions of suspended particles (less than about 0.2). The purpose of this paper is to examine the change in yeast plasma membrane permittivity after heating treatment, by using the Pauly and Schwan's theory.

  3. Effects of membrane disruption on dielectric properties of biological cells

    International Nuclear Information System (INIS)

    Disruption of the plasma membrane causes serious changes in the dielectric properties of biological cells. The changes have been simulated with spherical cell models having holes in the plasma membrane. The complex permittivity of a cubic system including a cell model was calculated by a numerical technique based on the three-dimensional finite difference method. For a cell without hole, the complex permittivity showed dielectric relaxation (β-dispersion) as predicted from interfacial polarization theories for the single-shell model. When there is one hole in the membrane, the cell has anisotropic dielectric properties depending on whether the axis through the centres of the hole and the sphere is parallel (the parallel orientation) or perpendicular (the perpendicular orientation) to the electric field direction. In the parallel orientation, dielectric relaxation (called 'α-dispersion') appeared at lower frequencies in addition to the β-dispersion, whereas only the β-dispersion was found in the perpendicular orientation. When there were two holes at the opposite poles of the cell, the 'α-dispersion' did not appear and the intensity of the β-dispersion decreased with increasing size of the holes. When two holes located in the hemisphere of the cell, however, the 'α-dispersion' appeared again. These results suggest that the occurrence of the 'α-dispersion' requires either the presence of one hole or the localization of holes

  4. Dynamic Heterogeneous Dielectric Generalized Born (DHDGB): An implicit membrane model with a dynamically varying bilayer thickness

    OpenAIRE

    Panahi, Afra; Feig, Michael

    2013-01-01

    An extension to the heterogeneous dielectric generalized Born (HDGB) implicit membrane formalism is presented to allow dynamic membrane deformations in response to membrane-inserted biomolecules during molecular dynamic simulations. The flexible membrane is implemented through additional degrees of freedom that represent the membrane deformation at the contact points of a membrane-inserted solute with the membrane. The extra degrees of freedom determine the dielectric and non-polar solvation ...

  5. Cavity optomechanics with arrays of thick dielectric membranes

    CERN Document Server

    Nair, Bhagya; Dantan, Aurelien

    2016-01-01

    Optomechanical arrays made of structured flexible dielectrics are a promising system for exploring quantum and many-body optomechanical phenomena. We generalize investigations of the optomechanical properties of periodic arrays of one-dimensional scatterers in optical resonators to the case of vibrating membranes whose thickness is not necessarily small with respect to the optical wavelength of interest. The array optical transmission spectrum and its optomechanical coupling with a linear Fabry-Perot cavity field are investigated both analytically and numerically.

  6. Optimization Design for a Dielectric Elastomer Membrane Actuator

    Science.gov (United States)

    He, Tianhu; Li, Yanyan; Li, Huimin; Chen, Cheng

    2013-03-01

    Due to the large voltage-induced strain along with other unique attributes, dielectric elastromers are being developed as transducers for broad applications in soft robots, adaptive structures, medical devices, energy harvesting and so on. Due to nonlinear large deformation and diverse modes of failure, it has been challenging to model dielectric transducers. This paper focuses on the optimization design of an actuator made of a layer of dielectric elastomer membrane and deformed into an out-of plane axisymmetric shape. The optimization procedure is demonstrated by examining the effect of three designing parameters, originated from the pre-stretch of the membrane, on the performance of the actuator, and by determining the region of allowable states in terms of several typical modes of failure. The equations of state are solved numerically by shooting method and the obtained numerical results indicate that the considered variables are sensitive to the designing parameters and that it is feasible to improve the performance of the actuator by choosing the designing parameters judiciously and averting the modes of failure. The approach presented here provides some guidelines in optimizing such actuators.

  7. Dielectric relaxations on erythrocyte membrane as revealed by spectrin denaturation.

    Science.gov (United States)

    Ivanov, I T; Paarvanova, B

    2016-08-01

    We studied the effect of spectrin denaturation at 49.5°C (TA) on the dielectric relaxations and related changes in the complex impedance, Z*, complex capacitance, C*, and dielectric loss curve of suspensions containing human erythrocytes, erythrocyte ghost membranes (EMs) and Triton-X-100 residues of EMs. The loss curve prior to, minus the loss curve after TA, resulted in a bell-shaped peak at 1.5MHz. The changes in the real and imaginary components of Z* and C* at TA, i.e., ΔZre, ΔZim, ΔCre and ΔCim, calculated in the same way, strongly varied with frequency. Between 1.0 and 12MHz the -ΔZim vs ΔZre, and ΔCim vs ΔCre plots depicted semicircles with critical frequencies, fcr, at 2.5MHz expressing recently reported relaxation of spectrin dipoles. Between 0.02 and 1.0MHz the -ΔZim vs ΔZre plot exhibited another relaxation whose fcr mirrored that of beta relaxation. This relaxation was absent on Triton-X-shells, while on erythrocytes and EMs it was inhibited by selective dissociation of either attachment sites between spectrin and bilayer. Considering above findings and inaccessibility of cytosole to outside field at such frequencies, the latter relaxation was assumed originating from a piezoelectric effect on the highly deformable spectrin filaments. PMID:27071054

  8. Polymethylmethacrylate/Fe3O4 composite nanofiber membranes with ultra-low dielectric permittivity

    Science.gov (United States)

    Zhang, C. C.; Li, X.; Yang, Y.; Wang, C.

    2009-11-01

    Ultra-low dielectric permittivity poly (methyl methacrylate)/Fe3O4 composite fiber membranes have been successfully prepared using electrospinning. The composite membranes were characterized by SEM (scanning electron microscopy), TEM (transmission electron microscopy), FT-IR (Fourier transform infrared), XRD (X-ray diffraction) and a radio frequency (RF) impedance/capacitance material analyzer. The magnetic measurement showed that the composite membranes displayed the super-paramagnetic property. The results showed that the dielectric permittivity of the composite fiber membranes was decreasing with increasing Fe3O4 nanoparticle content.

  9. Kinetics of nanopore fabrication during controlled breakdown of dielectric membranes in solution

    Science.gov (United States)

    Briggs, Kyle; Charron, Martin; Kwok, Harold; Le, Timothea; Chahal, Sanmeet; Bustamante, José; Waugh, Matthew; Tabard-Cossa, Vincent

    2015-02-01

    Nanopore fabrication by controlled breakdown (CBD) overcomes many of the challenges of traditional nanofabrication techniques, by reliably forming solid-state nanopores sub-2 nm in size in a low-cost and scalable way for nucleic acid analysis applications. Herein, the breakdown kinetics of thin dielectric membranes immersed in a liquid environment are investigated in order to gain deeper insights into the mechanism of solid-state nanopore formation by high electric fields. For various fabrication conditions, we demonstrate that nanopore fabrication time is Weibull-distributed, in support of the hypothesis that the fabrication mechanism is a stochastic process governed by the probability of forming a connected path across the membrane (i.e. a weakest-link problem). Additionally, we explore the roles that various ions and solvents play in breakdown kinetics, revealing that asymmetric pH conditions across the membrane can significantly affect nanopore fabrication time for a given voltage polarity. These results, characterizing the stochasticity of the nanopore fabrication process and highlighting the parameters affecting it, should assist researchers interested in exploiting the potential of CBD for nanofluidic channel fabrication, while also offering guidance towards the conceivable manufacturing of solid-state nanopore-based technologies for DNA sequencing applications.

  10. Dielectric response of biconcave erythrocyte membranes to D- and L-Glucose

    Energy Technology Data Exchange (ETDEWEB)

    Livshits, L [Department of Applied Physics, Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Caduff, A [Solianis Monitoring AG, Leutschenbachstr. 46, CH-8050 Zurich (Switzerland); Talary, M S [Solianis Monitoring AG, Leutschenbachstr. 46, CH-8050 Zurich (Switzerland); Feldman, Y [Department of Applied Physics, Hebrew University of Jerusalem, 91904 Jerusalem (Israel)

    2007-01-07

    In this paper, we report on the influence of D- and L-glucose on the dielectric properties of native shaped (biconcave) human erythrocytes using time domain dielectric spectroscopy. The dielectric spectra of biconcave cells were analysed using a modified form of the model originally reported for spheroid particle suspensions (Asami and Yonezawa 1995 Biochim. Biophys. Acta. 1245 317-24) The observed increase in the specific membrane capacitance of the biconcave erythrocytes was correlated with an increase in the concentration of D-glucose. In contrast, no associated correlation was found to changes in the membrane capacitance with increasing concentrations of L-glucose. A similar analysis of the dielectric response of osmotically swollen erythrocytes to changes in D-glucose concentration revealed a significantly different calculated specific cell membrane capacitance at elevated (>12 mM) D-glucose concentrations. The paper outlines and discusses the possible biochemical mechanisms that could be responsible for the measured dielectric properties of the erythrocyte membrane capacitances.

  11. Nonlinear deformation analysis of a dielectric elastomer membrane-spring system

    Science.gov (United States)

    He, Tianhu; Cui, Leilei; Chen, Cheng; Suo, Zhigang

    2010-08-01

    Due to their large strain capability, dielectric elastomers are promising materials for application as transducers in cameras, robots, valves, pumps, energy harvesters, and so on. The dielectric elastomer transducers are based on the deformation of a soft polymer membrane contracting in thickness and expanding in area, induced by the application of a voltage across the two compliant electrodes coated on both sides of the membrane. This paper focuses on the static large deformation analysis of a dielectric elastomer membrane-spring system. The system is constructed from attaching a disk in the middle of a circular dielectric membrane and then connecting the disk with a spring. This configuration can be potentially used as a key part in valves. The basic governing equations describing the large out-of-plane deformations are formulated, and the obtained equations are solved numerically. The relations related to the displacement of the disk, the spring force, the applied voltage, and the parameters of spring including stiffness and initial length are illustrated. The results show that the anticipated displacement of the disk can be controlled by adjusting either or both of the parameters of the spring and the applied voltage. In addition, the parameters of the spring, that is, the stiffness and the initial length, play an important role in the performance of the membrane-spring system.

  12. Electrostatic energy barriers from dielectric membranes upon approach of translocating DNA molecules

    Science.gov (United States)

    Buyukdagli, Sahin; Ala-Nissila, T.

    2016-02-01

    We probe the electrostatic cost associated with the approach phase of DNA translocation events. Within an analytical theory at the Debye-Hückel level, we calculate the electrostatic energy of a rigid DNA molecule interacting with a dielectric membrane. For carbon or silicon based low permittivity neutral membranes, the DNA molecule experiences a repulsive energy barrier between 10 kBT and 100 kBT. In the case of engineered membranes with high dielectric permittivities, the membrane surface attracts the DNA with an energy of the same magnitude. Both the repulsive and attractive interactions result from image-charge effects and their magnitude survive even for the thinnest graphene-based membranes of size d ≈ 6 Å. For weakly charged membranes, the electrostatic energy is always attractive at large separation distances but switches to repulsive close to the membrane surface. We also characterise the polymer length dependence of the interaction energy. For specific values of the membrane charge density, low permittivity membranes repel short polymers but attract long polymers. Our results can be used to control the strong electrostatic energy of DNA-membrane interactions prior to translocation events by chemical engineering of the relevant system parameters.

  13. Relaxational study of poly(vinylpyrrolidone-co-butyl acrylate) membrane by dielectric and dynamic mechanical spectroscopy

    International Nuclear Information System (INIS)

    A poly(vinylpyrrolidone-co-butyl acrylate) (60VP-40BA) membrane is synthesized as a tractable and hydrophilic material, obtaining a water-swelling percentage around 60%. An investigation of molecular mobility by means of differential scanning calorimetry, dynamic mechanical analysis and broadband dielectric relaxation spectroscopy (DRS) is fulfilled in the dry membrane. Dielectric and viscoelastic relaxation measurements are carried out on the 60VP-40BA sample at several frequencies between −150 and 150 °C. The dielectric spectrum shows several relaxation processes labelled γ, β and α in increasing order of temperature, whereas in the mechanical spectrum only the β and α relaxation processes are completely defined. In the dielectric measurements, conductive contributions overlap the α-relaxation. The apparent activation energies have similar values for the β-relaxation in both, the mechanical and the dielectric measurements. The β process is a Johari–Golstein secondary relaxation and it is related to the local motions of the pyrrolidone group accompanied by the motion of the segments of the polymer backbone. The γ process is connected with the butyl unit's motions, both located in the side chains of the polymer. (paper)

  14. Nonlinear Dielectric Spectroscopy as an Indirect Probe of Metabolic Activity in Thylakoid Membrane

    Directory of Open Access Journals (Sweden)

    John H. Miller

    2011-01-01

    Full Text Available Nonlinear dielectric spectroscopy (NDS is a non-invasive probe of cellular metabolic activity with potential application in the development of whole-cell biosensors. However, the mechanism of NDS interaction with metabolic membrane proteins is poorly understood, partly due to the inherent complexity of single cell organisms. Here we use the light-activated electron transport chain of spinach thylakoid membrane as a model system to study how NDS interacts with metabolic activity. We find protein modification, as opposed to membrane pump activity, to be the dominant source of NDS signal change in this system. Potential mechanisms for such protein modifications include reactive oxygen species generation and light-activated phosphorylation.

  15. Dielectric spectroscopy study of specific glucose influence on human erythrocyte membranes

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Yoshihito [Department of Applied Physics, Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Livshits, Leonid [Department of Applied Physics, Hebrew University of Jerusalem, 91904 Jerusalem (Israel); Caduff, Andreas [Pendragon Medical Ltd., Hagenholzstrasse 81a, CH-8050 Zurich (Switzerland); Feldman, Yuri [Department of Applied Physics, Hebrew University of Jerusalem, 91904 Jerusalem (Israel)

    2003-02-21

    Time domain dielectric spectroscopy has been used to study spherical erythrocytes, suspended in diluted phosphate buffered saline (PBS) buffers at varying concentrations of D- and L-glucose at 25 deg. C. The osmolarity for each glucose solution was adapted, equalling that of a 63% PBS (183 mOsm). The strong effect of the electrode polarization was corrected using the fractal approach in time domain. For analysis of the dielectric properties of suspensions of erythrocytes, the Maxwell-Wagner model is used for small volume fractions. Values of the permittivity and conductivity of the cell membrane were obtained from a fitting procedure according to the one-shell model. The non-monotonic and specific response of membrane electric properties on D-glucose concentrations were observed, with a dramatic decrease around 12 mM. No changes of membrane properties have been observed in the presence of increasing concentrations of L-glucose, the biologically inactive enantiomer of D-glucose. The effect is thus specific to D-glucose. The possible mechanism of specific cell reaction to D-glucose is discussed in this paper.

  16. Quantitative modeling of viable cell density, cell size, intracellular conductivity, and membrane capacitance in batch and fed-batch CHO processes using dielectric spectroscopy.

    Science.gov (United States)

    Opel, Cary F; Li, Jincai; Amanullah, Ashraf

    2010-01-01

    Dielectric spectroscopy was used to analyze typical batch and fed-batch CHO cell culture processes. Three methods of analysis (linear modeling, Cole-Cole modeling, and partial least squares regression), were used to correlate the spectroscopic data with routine biomass measurements [viable packed cell volume, viable cell concentration (VCC), cell size, and oxygen uptake rate (OUR)]. All three models predicted offline biomass measurements accurately during the growth phase of the cultures. However, during the stationary and decline phases of the cultures, the models decreased in accuracy to varying degrees. Offline cell radius measurements were unsuccessfully used to correct for the deviations from the linear model, indicating that physiological changes affecting permittivity were occurring. The beta-dispersion was analyzed using the Cole-Cole distribution parameters Deltaepsilon (magnitude of the permittivity drop), f(c) (critical frequency), and alpha (Cole-Cole parameter). Furthermore, the dielectric parameters static internal conductivity (sigma(i)) and membrane capacitance per area (C(m)) were calculated for the cultures. Finally, the relationship between permittivity, OUR, and VCC was examined, demonstrating how the definition of viability is critical when analyzing biomass online. The results indicate that the common assumptions of constant size and dielectric properties used in dielectric analysis are not always valid during later phases of cell culture processes. The findings also demonstrate that dielectric spectroscopy, while not a substitute for VCC, is a complementary measurement of viable biomass, providing useful auxiliary information about the physiological state of a culture. PMID:20730773

  17. Polymer thick-film conductors and dielectrics for membrane switches and flexible circuitry

    Science.gov (United States)

    Nazarenko, N.

    1983-01-01

    The fabrication and operation of membrane switches are discussed. The membrane switch functions as a normally open, momentary contact, low-voltage pressure-sensitive device. Its design is a three-layer sandwich usually constructed of polyester film. Conductive patterns are deposited onto the inner side of top and bottom sheets by silk screening. The center spacer is then placed between the two circuit layers to form a sandwich, generally held together by an adhesive. When pressure is applied to the top layer, it flexes through the punched openings of the spacer to establish electrical contact between conductive pads of the upper and lower sheets, momentarily closing the circuit. Upon release of force the top sheet springs back to its normal open position. The membrane touch switch is being used in a rapidly expanding range of applications, including instrumentation, appliances, electronic games and keyboards. Its board acceptance results from its low cost, durability, ease of manufacture, cosmetic appeal and design flexibility. The principal electronic components in the membrane switch are the conductor and dielectric.

  18. Fish-like propulsion of an airship with planar membrane dielectric elastomer actuators

    International Nuclear Information System (INIS)

    The goal of our project is to mimic fish-like movement in air, propelling an airship by undulating its hull and a caudal fin. The activation of the fish-like body in air is realized by dielectric elastomers. These actuators are quite unique for their soft light-weight membrane structure and they are therefore very appropriate to the application on inflated structures. The principles of biomimetics for the structural design and movement are discussed and the conception and design of the airship is described. Various development tests, including wind tunnel testing and flight trials, were performed and the results obtained are presented. It can be shown that an 8 m model airship can be propelled in a fish-like manner in air and that the propulsion can be drastically improved by undulating the body as well as the caudal fin contrary to propulsion with only the caudal fin.

  19. Fish-like propulsion of an airship with planar membrane dielectric elastomer actuators.

    Science.gov (United States)

    Jordi, C; Michel, S; Fink, E

    2010-06-01

    The goal of our project is to mimic fish-like movement in air, propelling an airship by undulating its hull and a caudal fin. The activation of the fish-like body in air is realized by dielectric elastomers. These actuators are quite unique for their soft light-weight membrane structure and they are therefore very appropriate to the application on inflated structures. The principles of biomimetics for the structural design and movement are discussed and the conception and design of the airship is described. Various development tests, including wind tunnel testing and flight trials, were performed and the results obtained are presented. It can be shown that an 8 m model airship can be propelled in a fish-like manner in air and that the propulsion can be drastically improved by undulating the body as well as the caudal fin contrary to propulsion with only the caudal fin. PMID:20498517

  20. Fish-like propulsion of an airship with planar membrane dielectric elastomer actuators

    Energy Technology Data Exchange (ETDEWEB)

    Jordi, C; Michel, S [Empa, Swiss Federal Laboratories for Material Testing and Research, Ueberlandstr. 129, 8600 Duebendorf (Switzerland); Fink, E, E-mail: christa.jordi@empa.c [TU Berlin, Berlin (Germany)

    2010-06-15

    The goal of our project is to mimic fish-like movement in air, propelling an airship by undulating its hull and a caudal fin. The activation of the fish-like body in air is realized by dielectric elastomers. These actuators are quite unique for their soft light-weight membrane structure and they are therefore very appropriate to the application on inflated structures. The principles of biomimetics for the structural design and movement are discussed and the conception and design of the airship is described. Various development tests, including wind tunnel testing and flight trials, were performed and the results obtained are presented. It can be shown that an 8 m model airship can be propelled in a fish-like manner in air and that the propulsion can be drastically improved by undulating the body as well as the caudal fin contrary to propulsion with only the caudal fin.

  1. Factors affecting the stability of chloroplast membranes in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Takaoki, T.; Torres-Pereira, J.; Packer, L.

    1974-01-01

    Factors which affect the stability of light-induced atebrin fluorescence quenching activity in chloroplast membranes, a measure of the electron transport dependent formation of energy-linked H/sup +/ gradients, were investigated in vitro. Class II spinach chloroplast membranes were isolated and stored at 0 to 4/sup 0/C and aliquots were subsequently tested for their retention of energizing capacity. The main factors which increase the stability of this activity were found to be (a) isolation in a potassium-containing medium but storage in a sucrose medium containing a low concentration of electrolytes; (b) the presence of butylated hydroxytoluene (an antioxidant), and a protein such as bovine serum albumin to remove free fatty acids in the medium during storage. Under these conditions, the energization capacity of chloroplasts is retained for more than 40 days.

  2. Tuning nano electric field to affect restrictive membrane area on localized single cell nano-electroporation

    Science.gov (United States)

    Santra, Tuhin Subhra; Wang, Pen-Cheng; Chang, Hwan-You; Tseng, Fan-Gang

    2013-12-01

    Interaction of electric field with biological cells is an important phenomenon for field induced drug delivery system. We demonstrate a selective and localized single cell nano-electroporation (LSCNEP) by applying an intense electric field on a submicron region of the single cell membrane, which can effectively allow high efficient molecular delivery but low cell damage. The delivery rate is controlled by adjusting transmembrane potential and manipulating membrane status. Thermal and ionic influences are deteriorated from the cell membrane by dielectric passivation. Either reversible or irreversible by LSCNEP can fully controlled with potential applications in medical diagnostics and biological studies.

  3. Dielectric behavior of different nanofillers incorporated in PVC-PMMA based polymer electrolyte membranes

    Science.gov (United States)

    Sowmya, G.; Pradeepa, P.; Kalaiselvimary, J.; Edwinraj, S.; Prabhu, M. Ramesh

    2016-05-01

    The Poly (methyl methacrylate) (PMMA)-Poly (vinyl chloride) (PVC) based polymer electrolytes were prepared by solvent casting technique. The prepared polymer electrolytes were subjected to conductivity studies by using electrochemical impedance spectroscopy and the maximum ionic conductivity value was found to be 0.8011 × 10-3 Scm-1 at 303K for PVC (17.5wt%) - PMMA (7.5wt %) - LiClO4 (8wt %) - PC (67wt %) - BaTiO3 (8wt%) electrolyte system. The dielectric behavior of the samples also studied.

  4. Alteration of membrane phospholipid methylation by adenosine analogs does not affect T lymphocyte activation

    International Nuclear Information System (INIS)

    Membrane phospholipid methylation has been described during activation of various immune cells. Moreover recent data indicated modulation of immune cells functions by adenosine. As S-adenosyl-methionine and S-adenosyl-homocysteine are adenosine analogs and modulators of transmethylation reactions, the effects of SAH and SAM were investigated on membrane phospholipid methylation and lymphocyte activation. SAM was shown to induce the membrane phospholipid methylation as assessed by the 3Hmethyl-incorporation in membrane extract. This effect was inhibited by SAH. In contrast SAM and SAH did not affect the phytohemagglutinin-induced proliferative response of peripheral blood mononuclear cells. SAH neither modified the early internalization of membrane CD3 antigens nor did it prevent the late expression of HLA-DR antigens on lymphocytes activated by phytohemagglutinin. These results indicate that in vitro alteration of phospholipid methylation does not affect subsequent steps of human T lymphocyte activation and proliferation

  5. Phosphocreatine interacts with phospholipids, affects membrane properties and exerts membrane-protective effects.

    Directory of Open Access Journals (Sweden)

    Malgorzata Tokarska-Schlattner

    Full Text Available A broad spectrum of beneficial effects has been ascribed to creatine (Cr, phosphocreatine (PCr and their cyclic analogues cyclo-(cCr and phospho-cyclocreatine (PcCr. Cr is widely used as nutritional supplement in sports and increasingly also as adjuvant treatment for pathologies such as myopathies and a plethora of neurodegenerative diseases. Additionally, Cr and its cyclic analogues have been proposed for anti-cancer treatment. The mechanisms involved in these pleiotropic effects are still controversial and far from being understood. The reversible conversion of Cr and ATP into PCr and ADP by creatine kinase, generating highly diffusible PCr energy reserves, is certainly an important element. However, some protective effects of Cr and analogues cannot be satisfactorily explained solely by effects on the cellular energy state. Here we used mainly liposome model systems to provide evidence for interaction of PCr and PcCr with different zwitterionic phospholipids by applying four independent, complementary biochemical and biophysical assays: (i chemical binding assay, (ii surface plasmon resonance spectroscopy (SPR, (iii solid-state (31P-NMR, and (iv differential scanning calorimetry (DSC. SPR revealed low affinity PCr/phospholipid interaction that additionally induced changes in liposome shape as indicated by NMR and SPR. Additionally, DSC revealed evidence for membrane packing effects by PCr, as seen by altered lipid phase transition. Finally, PCr efficiently protected against membrane permeabilization in two different model systems: liposome-permeabilization by the membrane-active peptide melittin, and erythrocyte hemolysis by the oxidative drug doxorubicin, hypoosmotic stress or the mild detergent saponin. These findings suggest a new molecular basis for non-energy related functions of PCr and its cyclic analogue. PCr/phospholipid interaction and alteration of membrane structure may not only protect cellular membranes against various insults

  6. Lipidome analysis reveals antifungal polyphenol curcumin affects membrane lipid homeostasis.

    Science.gov (United States)

    Sharma, Monika; Dhamgaye, Sanjiveeni; Singh, Ashutosh; Prasad, Rajendra

    2012-01-01

    This study shows that antifungal curcumin (CUR), significantly depletes ergosterol levels in Candida albicans. CUR while displaying synergy with fluconazole (FLC) lowers ergosterol. However, CUR alone at its synergistic concentration (lower than MIC50), could not affect ergosterol contents. For deeper insight of CUR effects on lipids, we performed high throughput mass spectroscopy (MS) based lipid profiling of C. albicans cells. The lipidome analysis revealed that there were no major changes in phosphoglycerides (PGLs) composition following CUR treatment of Candida, however, significant differences in molecular species of PGLs were detected. Among major SPLs, CUR treatment resulted in the reduction of ceramide and accumulation of IPCs levels. The lipidome of CUR treated cells confirmed a dramatic drop in the ergosterol levels with a simultaneous accumulation of its biosynthetic precursors. This was further supported by the fact that the mutants defective in ergosterol biosynthesis (ERG2 and ERG11) and those lacking the transcription factor regulating ergosterol biosynthesis, UPC2, were highly susceptible to CUR. Our study first time shows that CUR, for its antifungal activity, targets and down regulates delta 5, 6 desaturase (ERG3) resulting in depletion of ergosterol. This results in parallel accumulation of ergosterol biosynthetic precursors, generation of reactive oxygen species (ROS) and cell death. PMID:22201946

  7. Membrane bending by protein crowding is affected by protein lateral confinement.

    Science.gov (United States)

    Derganc, Jure; Čopič, Alenka

    2016-06-01

    Crowding of asymmetrically-distributed membrane proteins has been recently recognized as an important factor in remodeling of biological membranes, for example during transport vesicle formation. In this paper, we theoretically analyze the effect of protein crowding on membrane bending and examine its dependence on protein size, shape, transmembrane asymmetry and lateral confinement. We consider three scenarios of protein lateral organization, which are highly relevant for cellular membranes in general: freely diffusing membrane proteins without lateral confinement, the presence of a diffusion barrier and interactions with a vesicular coat. We show that protein crowding affects vesicle formation even if the proteins are distributed symmetrically across the membrane and that this effect depends significantly on lateral confinement. The largest crowding effect is predicted for the proteins that are confined to the forming vesicle by a diffusion barrier. We calculate the bending properties of a crowded membrane and find that its spontaneous curvature depends primarily on the degree of transmembrane asymmetry, and its effective bending modulus on the type of lateral confinement. Using the example of COPII vesicle formation from the endoplasmic reticulum, we analyze the energetic cost of vesicle formation. The results provide a novel insight into the effects of lateral and transmembrane organization of membrane proteins, and can guide data interpretation and future experimental approaches. PMID:26969088

  8. A High Sensitivity IDC-Electronic Tongue Using Dielectric/Sensing Membranes with Solvatochromic Dyes

    Directory of Open Access Journals (Sweden)

    Md. Rajibur Rahaman Khan

    2016-05-01

    Full Text Available In this paper, an electronic tongue/taste sensor array containing different interdigitated capacitor (IDC sensing elements to detect different types of tastes, such as sweetness (glucose, saltiness (NaCl, sourness (HCl, bitterness (quinine-HCl, and umami (monosodium glutamate is proposed. We present for the first time an IDC electronic tongue using sensing membranes containing solvatochromic dyes. The proposed highly sensitive (30.64 mV/decade sensitivity IDC electronic tongue has fast response and recovery times of about 6 s and 5 s, respectively, with extremely stable responses, and is capable of linear sensing performance (R2 ≈ 0.985 correlation coefficient over the wide dynamic range of 1 µM to 1 M. The designed IDC electronic tongue offers excellent reproducibility, with a relative standard deviation (RSD of about 0.029. The proposed device was found to have better sensing performance than potentiometric-, cascoded compatible lateral bipolar transistor (C-CLBT-, Electronic Tongue (SA402-, and fiber-optic-based taste sensing systems in what concerns dynamic range width, response time, sensitivity, and linearity. Finally, we applied principal component analysis (PCA to distinguish between various kinds of taste in mixed taste compounds.

  9. A High Sensitivity IDC-Electronic Tongue Using Dielectric/Sensing Membranes with Solvatochromic Dyes

    Science.gov (United States)

    Khan, Md. Rajibur Rahaman; Khalilian, Alireza; Kang, Shin-Won

    2016-01-01

    In this paper, an electronic tongue/taste sensor array containing different interdigitated capacitor (IDC) sensing elements to detect different types of tastes, such as sweetness (glucose), saltiness (NaCl), sourness (HCl), bitterness (quinine-HCl), and umami (monosodium glutamate) is proposed. We present for the first time an IDC electronic tongue using sensing membranes containing solvatochromic dyes. The proposed highly sensitive (30.64 mV/decade sensitivity) IDC electronic tongue has fast response and recovery times of about 6 s and 5 s, respectively, with extremely stable responses, and is capable of linear sensing performance (R2 ≈ 0.985 correlation coefficient) over the wide dynamic range of 1 µM to 1 M. The designed IDC electronic tongue offers excellent reproducibility, with a relative standard deviation (RSD) of about 0.029. The proposed device was found to have better sensing performance than potentiometric-, cascoded compatible lateral bipolar transistor (C-CLBT)-, Electronic Tongue (SA402)-, and fiber-optic-based taste sensing systems in what concerns dynamic range width, response time, sensitivity, and linearity. Finally, we applied principal component analysis (PCA) to distinguish between various kinds of taste in mixed taste compounds. PMID:27171095

  10. A High Sensitivity IDC-Electronic Tongue Using Dielectric/Sensing Membranes with Solvatochromic Dyes.

    Science.gov (United States)

    Khan, Md Rajibur Rahaman; Khalilian, Alireza; Kang, Shin-Won

    2016-01-01

    In this paper, an electronic tongue/taste sensor array containing different interdigitated capacitor (IDC) sensing elements to detect different types of tastes, such as sweetness (glucose), saltiness (NaCl), sourness (HCl), bitterness (quinine-HCl), and umami (monosodium glutamate) is proposed. We present for the first time an IDC electronic tongue using sensing membranes containing solvatochromic dyes. The proposed highly sensitive (30.64 mV/decade sensitivity) IDC electronic tongue has fast response and recovery times of about 6 s and 5 s, respectively, with extremely stable responses, and is capable of linear sensing performance (R² ≈ 0.985 correlation coefficient) over the wide dynamic range of 1 µM to 1 M. The designed IDC electronic tongue offers excellent reproducibility, with a relative standard deviation (RSD) of about 0.029. The proposed device was found to have better sensing performance than potentiometric-, cascoded compatible lateral bipolar transistor (C-CLBT)-, Electronic Tongue (SA402)-, and fiber-optic-based taste sensing systems in what concerns dynamic range width, response time, sensitivity, and linearity. Finally, we applied principal component analysis (PCA) to distinguish between various kinds of taste in mixed taste compounds. PMID:27171095

  11. Dielectric materials for electrical engineering

    CERN Document Server

    Martinez-Vega, Juan

    2013-01-01

    Part 1 is particularly concerned with physical properties, electrical ageing and modeling with topics such as the physics of charged dielectric materials, conduction mechanisms, dielectric relaxation, space charge, electric ageing and life end models and dielectric experimental characterization. Part 2 concerns some applications specific to dielectric materials: insulating oils for transformers, electrorheological fluids, electrolytic capacitors, ionic membranes, photovoltaic conversion, dielectric thermal control coatings for geostationary satellites, plastics recycling and piezoelectric poly

  12. The antiproliferative properties of the milk fat globule membrane are affected by extensive heating

    OpenAIRE

    Zanabria, Romina; Tellez, Angela; Griffiths, Mansel; Corredig, Milena

    2014-01-01

    The milk fat globule membrane (MFGM), the material surrounding milk fat globules, is not only interesting from a technological standpoint but it also shows great potential as a health ingredient, as it exerts cytotoxic and apoptotic effects against colon cancer cells. Although the effects of milk processing on the MFGM composition and functionality are well documented, less is understood on how processing may affect its bioactivity. This study aimed to determine if heating can affect the anti...

  13. [MORPHOLOGICAL FEATURES OF RAT MUCOUS MEMBRANE OF THE TONGUE EARLY AFFECTED BY ACRYLIC RESIN MONOMER].

    Science.gov (United States)

    Davydenko, V; Nidzelskiy, M; Starchenko, I; Davydenko, A; Kuznetsov, V

    2016-03-01

    Base materials, made on the basis of various derivatives of acrylic and methacrylic acids, have been widely used in prosthetic dentistry. Free monomer, affecting the tissues of prosthetic bed and the whole body, is always found in dentures. Therefore, study of the effect of acrylic resins' monomer on mucous membrane of the tongue is crucial. Rat tongue is very similar to human tongue, and this fact has become the basis for selecting these animals to be involved into the experiment. The paper presents the findings related to the effect of "Ftoraks" base acrylic resin monomer on the state of rat mucous membrane of the tongue and its regeneration. The microscopy has found that the greatest changes in the mucous membrane of the tongue occur on day 3 and 7 day after applying the monomer and are of erosive and inflammatory nature. Regeneration of tongue epithelium slows down. PMID:27119844

  14. Application of forward osmosis membrane technology for oil sands process-affected water desalination.

    Science.gov (United States)

    Jiang, Yaxin; Liang, Jiaming; Liu, Yang

    2016-01-01

    The extraction process used to obtain bitumen from the oil sands produces large volumes of oil sands process-affected water (OSPW). As a newly emerging desalination technology, forward osmosis (FO) has shown great promise in saving electrical power requirements, increasing water recovery, and minimizing brine discharge. With the support of this funding, a FO system was constructed using a cellulose triacetate FO membrane to test the feasibility of OSPW desalination and contaminant removal. The FO systems were optimized using different types and concentrations of draw solution. The FO system using 4 M NH4HCO3 as a draw solution achieved 85% water recovery from OSPW, and 80 to 100% contaminant rejection for most metals and ions. A water backwash cleaning method was applied to clean the fouled membrane, and the cleaned membrane achieved 77% water recovery, a performance comparable to that of new FO membranes. This suggests that the membrane fouling was reversible. The FO system developed in this project provides a novel and energy efficient strategy to remediate the tailings waters generated by oil sands bitumen extraction and processing. PMID:27120634

  15. Are aortic endograft prostheses fully hemo-compatible? A dielectric spectroscopy investigation of the electrical alterations induced on erythrocyte cell membranes

    Energy Technology Data Exchange (ETDEWEB)

    Basoli, Antonio [Clinica Chirurgica II, Universita di Roma ' La Sapienza' , Rome (Italy); Bordi, Federico [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Rome (Italy); Cametti, Cesare [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Rome (Italy); Faraglia, Vittorio [Cattedra di Chirurgia Vascolare, Second School of Medicine, Universita di Roma ' La Sapienza' , Rome (Italy); Gili, Tommaso [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Rome (Italy); Rizzo, Luigi [Cattedra di Chirurgia Vascolare, Second School of Medicine, Universita di Roma ' La Sapienza' , Rome (Italy); Taurino, Maurizio [Cattedra di Chirurgia Vascolare, Second School of Medicine, Universita di Roma ' La Sapienza' , Rome (Italy)

    2007-03-01

    In this paper we present a new approach directed to ascertain the full hemo-compatibility of aortic endograft prostheses based on the measurement of the passive electrical parameters of the erythrocyte cell membrane. The red blood cell membrane, from an electric point of view, is characterized by an electrical permittivity, {epsilon}{sub s}, which takes into account the structural charged organization of the lipid double layer, and by the electrical conductivity, {sigma}{sub s}, which accounts for the ionic transport processes across the membrane. These parameters can be easily measured by means of a radiowave dielectric spectroscopy technique, analyzing the dependence of the electrical impedance of an erythrocyte suspension on the frequency of the applied electric field. In this preliminary report, we investigate the alterations induced, at a membrane level, by two different devices commonly employed for endovascular abdominal aortic aneurysm exclusion, i.e., Excluder (registered) and Zenith (registered) devices, implanted in ten patients. We observe, in all the cases investigated, a statistically significant increase of both the permittivity {epsilon}{sub s} and electrical conductivity {sigma}{sub s} of the erythrocyte membrane upon the prosthesis implant, this increase being higher than about 20% of the un-treated values. Moreover, these alterations remain roughly unaffected 30 days after surgery. These findings suggest that a complete hemo-compatibility of these prostheses is lacking, even if the observed alterations may not have a clinical relevance.

  16. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xiao [School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Hangkong Road 13, 430030, Wuhan (China); Schluesener, Hermann J, E-mail: mornsmile@yahoo.com [Institute of Brain Research, University of Tuebingen, Calwerstrasse 3, D-72076, Tuebingen (Germany)

    2010-03-12

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  17. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    Science.gov (United States)

    Chen, Xiao; Schluesener, Hermann J.

    2010-03-01

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  18. Multi-walled carbon nanotubes affect drug transport across cell membrane in rat astrocytes

    International Nuclear Information System (INIS)

    The impact of carbon nanotubes on the cell membrane is an aspect of particular importance and interest in the study of carbon nanotubes' interactions with living systems. One of the many functions of the cell membrane is to execute substance transport into and out of the cell. We investigated the influence of multi-walled carbon nanotubes (MWCNTs) on the transport of several compounds across in the cell membrane of rat astrocytes using flow cytometry. These compounds are fluorescein diacetate, carboxyfluorescein diacetate, rhodamine 123 and doxorubicin, which are prosubstrate/substrates of multidrug transporter proteins. Results showed that MWCNTs significantly inhibited cellular uptake of doxorubicin but not the other drugs and the mode of loading made a significant difference in doxorubicin uptake. Retention of fluorescein, carboxyfluorescein and rhodamine 123 was remarkably higher in MWCNT-exposed cells after an efflux period. A kinetics study also demonstrated slower efflux of intracellular fluorescein and rhodamine 123. Data presented in this paper suggest that MWCNTs could affect drug transport across cell membranes. The implications of the findings are discussed.

  19. Partial calcium depletion during membrane filtration affects gelation of reconstituted milk protein concentrates.

    Science.gov (United States)

    Eshpari, H; Jimenez-Flores, R; Tong, P S; Corredig, M

    2015-12-01

    Milk protein concentrate powders (MPC) with improved rehydration properties are often manufactured using processing steps, such as acidification and high-pressure processing, and with addition of other ingredients, such as sodium chloride, during their production. These steps are known to increase the amount of serum caseins or modify the mineral equilibrium, hence improving solubility of the retentates. The processing functionality of the micelles may be affected. The aim of this study was to investigate the effects of partial acidification by adding glucono-δ-lactone (GDL) to skim milk during membrane filtration on the structural changes of the casein micelles by observing their chymosin-induced coagulation behavior, as such coagulation is affected by both the supramolecular structure of the caseins and calcium equilibrium. Milk protein concentrates were prepared by preacidification with GDL to pH 6 using ultrafiltration (UF) and diafiltration (DF) followed by spray-drying. Reconstituted UF and DF samples (3.2% protein) treated with GDL showed significantly increased amounts of soluble calcium and nonsedimentable caseins compared with their respective controls, as measured by ion chromatography and sodium dodecyl sulfate-PAGE electrophoresis, respectively. The primary phase of chymosin-induced gelation was not significantly different between treatments as measured by the amount of caseino-macropeptide released. The rheological properties of the reconstituted MPC powders were determined immediately after addition of chymosin, both before and after dialysis against skim milk, to ensure similar serum composition for all samples. Reconstituted samples before dialysis showed no gelation (defined as tan δ=1), and after re-equilibration only control UF and DF samples showed gelation. The gelation properties of reconstituted MPC powders were negatively affected by the presence of soluble casein, and positively affected by the amount of both soluble and insoluble

  20. Study of the Optical and Physical Roles of a Dielectric Laser Dye Solvent Which Affects on the Dye Laser Operation

    Directory of Open Access Journals (Sweden)

    Riyad A.M. Ghazy

    2005-01-01

    Full Text Available It is well known that when the pump laser beam incidence on the laser dye liquid it will be absorbed. This absorption tends to heat the laser active medium, which is the laser dye solution. In view of this the correlated property of that active medium well change tends to shift the operated frequency and wavelength. Therefore, one of most interested dielectric, nonpolar, laser dye solvent was selected for this investigation, which is Benzene. A laser interferometer known as Mach Zhender Interferometer (MZI is constructed and used to measure the refractive index of the investigated solvent by counting the interfering fringes as a function of the angle of incidence of the incident laser beam. The temperature of that solvent is raised within the range 293-373 K by using a constructed heating system. The thermal behavior of the refractive index of Benzene is studied to estimate the thermo-optical coefficient of the refractive index, which is important to know the state convergence or divergence of the pump laser beam within the laser dye medium. Also, the dielectric constant of the dye solution is an important parameter for the laser operation. Therefore the dielectric constant and its thermal behavior of Benzene are calculated through the Maxwell’s relation to determine the thermal coefficient of the dielectric constant. The value of the number density which is equal the specific polarizability of the investigated solvent is estimated by using the obtained values of the refractive index and its variation with the temperature is studied too. Because the dependence of the mean polarizability of the dielectric constant through the Clausius-Mossotti relation the values of both mean polarizability and its thermal behavior are studied. In addition, since the molecular polarizability depends on the mean polarizability the value of it is determined. By using the values of mean polarizability the molecule radius is determined and using the Clausius

  1. Membrane protein assembly: two cytoplasmic phosphorylated serine sites of Vpu from HIV-1 affect oligomerization

    Science.gov (United States)

    Chen, Chin-Pei; Lin, Meng-Han; Chan, Ya-Ting; Chen, Li-Chyong; Ma, Che; Fischer, Wolfgang B.

    2016-01-01

    Viral protein U (Vpu) encoded by human immunodeficiency virus type 1 (HIV-1) is a short integral membrane protein which is known to self-assemble within the lipid membrane and associate with host factors during the HIV-1 infectivity cycle. In this study, full-length Vpu (M group) from clone NL4-3 was over-expressed in human cells and purified in an oligomeric state. Various single and double mutations were constructed on its phosphorylation sites to mimic different degrees of phosphorylation. Size exclusion chromatography of wild-type Vpu and mutants indicated that the smallest assembly unit of Vpu was a dimer and over time Vpu formed higher oligomers. The rate of oligomerization increased when (i) the degree of phosphorylation at serines 52 and 56 was decreased and (ii) when the ionic strength was increased indicating that the cytoplasmic domain of Vpu affects oligomerization. Coarse-grained molecular dynamic simulations with models of wild-type and mutant Vpu in a hydrated lipid bilayer supported the experimental data in demonstrating that, in addition to a previously known role in downregulation of host factors, the phosphorylation sites of Vpu also modulate oligomerization. PMID:27353136

  2. Lupus vulgaris: Isolation of Mycobacterium tuberculosis from the affected skin scraping and mucous membranes

    Directory of Open Access Journals (Sweden)

    Jovanović Marina

    2006-01-01

    Full Text Available Introduction. In the second half of the last century skin tuberculosis has become a rarity. With the appearance of resistance to different kinds of pathogenes, HIV-immunodeficiency and decreasing standard of living, the incidence of skin tuberculosis increses. Lupus vulgaris is a chronic form of the secondary tuberculosis of the skin. Case report. This is a case report of a 66-year-old woman who presented with a growing, painless, brownish-red, slab-shaped, jelly, cutanesous mass, 2.5 centimeters in diameter, on the tip of her nose, reaching the mucous membrane of the nose. Results. Apart from accelerated erythrocyte sedimentation rate (43/73 and a positive tuberculosis test (Mantoux 10 TU=25x25 mm, all relevant findings were within reference values. Using Ziehl-Neelsen staining, no acido-resistent bacilli were found. The skin scraping sample, taken from the affected skin and the mucous membrane, was cultivated in Lowenstein medium base, and this resulted with cultivation of Mycobacterium tuberculosis. Using three-drug combination therapy for ten months, complete remission was achieved. Conclusion. Successful cultivation of pathogens represents an absolute diagnostic criterion. We present a case of a woman with lupus vulgaris, because there is a small number of cases documented around the world where the diagnosis was confirmed by culture of Mycobacterium tuberculosis. .

  3. Membraner

    DEFF Research Database (Denmark)

    Bach, Finn

    2009-01-01

    Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner......Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner...

  4. Plasma membrane lipid-protein interactions affect signaling processes in sterol-biosynthesis mutants of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Henrik eZauber

    2014-03-01

    Full Text Available The plasma membrane is an important organelle providing structure, signaling and transport as major biological functions. Being composed of lipids and proteins with different physicochemical properties, the biological functions of membranes depend on specific protein-protein and protein-lipid interactions. Interactions of proteins with their specific sterol and lipid environment were shown to be important factors for protein recruitment into sub-compartmental structures of the plasma membrane. System-wide implications of altered endogenous sterol levels for membrane functions in living cells were not studied in higher plant cells. In particular, little is known how alterations in membrane sterol composition affect protein and lipid organization and interaction within membranes. Here, we conducted a comparative analysis of the plasma membrane protein and lipid composition in Arabidopsis sterol-biosynthesis mutants smt1 and ugt80A2;B1. smt1 shows general alterations in sterol composition while ugt80A2;B1 is significantly impaired in sterol glycosylation. By systematically analyzing different cellular fractions and combining proteomic with lipidomic data we were able to reveal contrasting alterations in lipid-protein interactions in both mutants, with resulting differential changes in plasma membrane signaling status.

  5. RNAi-mediated downregulation of poplar plasma membrane intrinsic proteins (PIPs) changes plasma membrane proteome composition and affects leaf physiology.

    Science.gov (United States)

    Bi, Zhen; Merl-Pham, Juliane; Uehlein, Norbert; Zimmer, Ina; Mühlhans, Stefanie; Aichler, Michaela; Walch, Axel Karl; Kaldenhoff, Ralf; Palme, Klaus; Schnitzler, Jörg-Peter; Block, Katja

    2015-10-14

    Plasma membrane intrinsic proteins (PIPs) are one subfamily of aquaporins that mediate the transmembrane transport of water. To reveal their function in poplar, we generated transgenic poplar plants in which the translation of PIP genes was downregulated by RNA interference investigated these plants with a comprehensive leaf plasma membrane proteome and physiome analysis. First, inhibition of PIP synthesis strongly altered the leaf plasma membrane protein composition. Strikingly, several signaling components and transporters involved in the regulation of stomatal movement were differentially regulated in transgenic poplars. Furthermore, hormonal crosstalk related to abscisic acid, auxin and brassinosteroids was altered, in addition to cell wall biosynthesis/cutinization, the organization of cellular structures and membrane trafficking. A physiological analysis confirmed the proteomic results. The leaves had wider opened stomata and higher net CO2 assimilation and transpiration rates as well as greater mesophyll conductance for CO2 (gm) and leaf hydraulic conductance (Kleaf). Based on these results, we conclude that PIP proteins not only play essential roles in whole leaf water and CO2 flux but have important roles in the regulation of stomatal movement. PMID:26248320

  6. Design and simulation of Pt-based microhotplate, and fabrication of suspended dielectric membrane by bulk micromachining

    Science.gov (United States)

    Prasad, Mahanth; Yadav, R. P.; Sahula, V.; Khanna, V. K.

    2012-10-01

    The paper presents the design and simulation of double spiral Pt-based microhotplate (MHP) for gas sensing application. A platinum resistor of 52 Ω has been designed and simulated on a 0.3 micron thick SiO2 suspended membrane of size 40 × 40 μm2 using ANSYS. The SiO2 membrane of size 40 × 40 μμm2 and thickness 0.3 micron has been fabricated successfully by bulk micromachining in TMAH) solution. The simulated temperature and transit time response of microhotplate were obtained as 600.5 °C and 0.2 ms respectively at 4.8 mW power consumption.

  7. Fluorescent styryl dyes of the RH series affect a potential drop on the membrane/solution boundary.

    Science.gov (United States)

    Malkov, D Y; Sokolov, V S

    1996-01-31

    The effects of the adsorption of the fluorescent potential-sensitive dyes RH-421, RH-237 and RH-160 on the bilayer lipid membrane were studied. It was shown that a dipole potential drop, positive in the hydrophobic part of the membrane, arose due to the dye adsorption. The dye adsorption led to a considerable increase of the rate constant of hydrophobic anion translocation through the membrane, but did not affect their partition coefficient between membrane and water. It implies that the region of the membrane where the potential drops is located deeper than the adsorption plane of hydrophobic ions. The values of boundary potential differences were estimated by two independent methods with unilateral and bilateral application of the dyes to lipid bilayer membranes. The results suggest that RH dye molecules penetrate through the lipid bilayers. The values of zeta-potential in liposomes did not change on dye adsorption. Hence, dye molecules are adsorbed in a form that does not change the surface charge. We estimated the effects of electric field of dye dipole layer on an individual dipole located in the same layer and on ion transport through a membrane protein Na+/K+-ATPase. It turned out that the local electric field of each dye dipole decayed so rapidly that a neighbouring dye molecule did not feel it. It also appeared that RH dyes could have but a minor effect on the electrogenic transport performed by the sodium pump in the examined range of dye concentrations. PMID:8593277

  8. Two coiled-coil domains of Chlamydia trachomatis IncA affect membrane fusion events during infection.

    Directory of Open Access Journals (Sweden)

    Erik Ronzone

    Full Text Available Chlamydia trachomatis replicates in a parasitophorous membrane-bound compartment called an inclusion. The inclusions corrupt host vesicle trafficking networks to avoid the degradative endolysosomal pathway but promote fusion with each other in order to sustain higher bacterial loads in a process known as homotypic fusion. The Chlamydia protein IncA (Inclusion protein A appears to play central roles in both these processes as it participates to homotypic fusion and inhibits endocytic SNARE-mediated membrane fusion. How IncA selectively inhibits or activates membrane fusion remains poorly understood. In this study, we analyzed the spatial and molecular determinants of IncA's fusogenic and inhibitory functions. Using a cell-free membrane fusion assay, we found that inhibition of SNARE-mediated fusion requires IncA to be on the same membrane as the endocytic SNARE proteins. IncA displays two coiled-coil domains showing high homology with SNARE proteins. Domain swap and deletion experiments revealed that although both these domains are capable of independently inhibiting SNARE-mediated fusion, these two coiled-coil domains cooperate in mediating IncA multimerization and homotypic membrane interaction. Our results support the hypothesis that Chlamydia employs SNARE-like virulence factors that positively and negatively affect membrane fusion and promote infection.

  9. Nonbilayer lipids affect peripheral and integral membrane proteins via changes in the lateral pressure profile.

    Science.gov (United States)

    van den Brink-van der Laan, Els; Killian, J Antoinette; de Kruijff, Ben

    2004-11-01

    Nonbilayer lipids can be defined as cone-shaped lipids with a preference for nonbilayer structures with a negative curvature, such as the hexagonal phase. All membranes contain these lipids in large amounts. Yet, the lipids in biological membranes are organized in a bilayer. This leads to the question: what is the physiological role of nonbilayer lipids? Different models are discussed in this review, with a focus on the lateral pressure profile within the membrane. Based on this lateral pressure model, predictions can be made for the effect of nonbilayer lipids on peripheral and integral membrane proteins. Recent data on the catalytic domain of Leader Peptidase and the potassium channel KcsA are discussed in relation to these predictions and in relation to the different models on the function of nonbilayer lipids. The data suggest a general mechanism for the interaction between nonbilayer lipids and membrane proteins via the membrane lateral pressure. PMID:15519321

  10. Simulation study for lifetime distribution of middle-of-line time-dependent dielectric breakdown affected by global and local spacing variations

    Science.gov (United States)

    Yokogawa, Shinji

    2016-06-01

    The impact of process fluctuations for the lifetime distribution of middle-of-line time-dependent dielectric breakdown was investigated by Monte-Carlo simulation. Global and local variations were simulated using a doubly truncated normal distribution. A goodness of fit to the generated data was determined statistically in terms of the Weibull distribution and clustering model. A change in the standard deviation of the global variation shows a large contribution to lifetime variation. However, it does not affect the average lifetime. A change in the standard deviation of the local variation contributes to both the average lifetime and the distribution variation. The upper limit of the process variation induces the convex upward shape of the lifetime distribution on the Weibull plot. The clustering model well explains the distribution shape.

  11. Changes in membrane lipid composition of Mycoplasma capricolum affect the cell volume.

    OpenAIRE

    N. Romano; Shirvan, M H; Rottem, S.

    1986-01-01

    The cellular water volume of Mycoplasma capricolum was markedly increased by a decrease in the cholesterol-to-phospholipid molar ratio in the membrane. An increase in cell volume was also observed with the increase in the phospholipid cell membrane content obtained by the incorporation of exogenous phosphatidylcholine from the growth medium.

  12. Biomass characterization by dielectric monitoring of viability and oxygen uptake rate measurements in a novel membrane bioreactor.

    Science.gov (United States)

    Shariati, Farshid Pajoum; Heran, Marc; Sarrafzadeh, Mohammad Hossein; Mehrnia, Mohammad Reza; Sarzana, Gabriele; Ghommidh, Charles; Grasmick, Alain

    2013-07-01

    The application of permittivity and oxygen uptake rate (OUR) as biological process control parameters in a wastewater treatment system was evaluated. Experiments were carried out in a novel airlift oxidation ditch membrane bioreactor under different organic loading rates (OLR). Permittivity as representative of activated sludge viability was measured by a capacitive on-line sensor. OUR was also measured as a representative for respirometric activity. Results showed that the biomass concentration increases with OLR and all biomass related measurements and simulators such as MLSS, permittivity, OUR, ASM1 and ASM3 almost follow the same increasing trends. The viability of biomass decreased when the OLR was reduced from 5 to 4 kg COD m(-3)d(-1). During decreasing of OLR, biomass related parameters generally decreased but not in a similar manner. Also, protein concentration in the system during OLR decreasing changed inversely with the activated sludge viability. PMID:23708851

  13. Launch Conditions Might Affect the Formation of Blood Vessel in the Quail Chorioallantoic Membrane

    Science.gov (United States)

    Henry, M. K.; Unsworth, B. R.; Sychev, B. R.; Guryeva, T. S.; Dadasheva, O. A.; Piert, S. J.; Lagel, K. E.; Dubrovin, L. C.; Jahns, G. C.; Boda, K.; Sabo, V.; Samet, M. M.; Lelkes, P. I.

    1998-01-01

    AS 2 part of the first joint USA-Russian MIR/Shuttle program, fertilized quail eggs were flown on the MIR 18 mission. Post-flight examination indicated impaired survival of both the embryos in space and also of control embryos exposed to vibrational and g-forces simulating the conditions experienced during the launch of Progress 227. We hypothesized that excess mechanical forces and/or other conditions during the launch might cause abnormal development of the blood supply in the chorioallantoic membrane (CAM) leading to the impaired survival of the embryos. The CAM, a highly vascularized extraembryonic organ, provides for the oxygen exchange across the egg shell and is thus pivotal for proper embryonic development. To test our hypothesis, we compared angiogenesis In CAMS of eggs which were either exposed to the vibration and g-force profile simulating the conditions at launch of Progress 227 (synchronous controls), or kept under routine conditions in a laboratory Incubator (laboratory controls). At various time points during Incubation, the eggs were fixed in paraformaldehyde for subsequent dissection. At the time of dissection, the CAM was carefully lifted from the egg shell and examined as whole mounts by bright-field and fluorescent microscopy. The development or the vasculature (angiogenesis) was assessed from the density of blood vessels per viewing field and evaluated by computer aided image analysis. We observed a significant decrease In blood-vessel density in the synchronous controls versus "normal" laboratory controls beginning from day 10 of Incubation. The decrease in vascular density was restricted to the smallest vessels only, suggesting that conditions during the launch and/or during the subsequent Incubation of the eggs may affect the normal progress of angiogenesis in the CAM. Abnormal angiogenesis In the CAM might contribute to the impaired survival of the embryos observed in synchronous controls as well as in space.

  14. Inhibition of sphingomyelin synthase (SMS) affects intracellular sphingomyelin accumulation and plasma membrane lipid organization

    OpenAIRE

    Li, Zhiqiang; Hailemariam, Tiruneh K.; Zhou, Hongwen; Li, Yan; Duckworth, Dale C.; Peake, David A.; Zhang, Youyan; Kuo, Ming-Shang; Cao, Guoqing; Jiang, Xian-Cheng

    2007-01-01

    Sphingomyelin plays a very important role both in cell membrane formation that may well have an impact on the development of diseases like atherosclerosis and diabetes. However, the molecular mechanism that governs intracellular and plasma membrane SM levels is largely unknown. Recently, two isoforms of sphingomyelin synthase (SMS1 and SMS2), the last enzyme for SM de novo synthesis, have been cloned. We have hypothesized that SMS1 and SMS2 are the two most likely candidates responsible for t...

  15. Acetaminophen Changes Intestinal Epithelial Cell Membrane Properties, Subsequently Affecting Absorption Processes

    Directory of Open Access Journals (Sweden)

    Christine Schäfer

    2013-08-01

    Full Text Available Background/Aims: Acetaminophen (APAP effects on intestinal barrier properties are less investigated. APAP may lead to a changed bioavailability of a subsequently administered drug or diet in the body. We investigated the influence of APAP on enterocytic cell membrane properties that are able to modify the net intestinal absorption of administered substances across the Caco-2 barrier model. Methods: The effect of APAP on cytotoxicity was measured by LDH assay, TER value and cell capacitance label-free using impedance monitoring, membrane permeability by FITC-dextrans, and efflux transporter MDR1 activity by Rh123. APAP levels were determined by HPLC analysis. Cell membrane topography and microvilli were investigated using SEM and intestinal alkaline phosphatase (Alpi and tight junction protein 1 (TJP1 expression by western blot analysis. Results: APAP changed the apical cell surface, reduced the number of microvilli and protein expression of Alpi as a brush border marker and TJP1, increased the membrane integrity and concurrently decreased cell capacitance over time. In addition, APAP decreased the permeability to small molecules and increased the efflux transporter activity, MDR1. Conclusion: APAP alters the Caco-2 cell membrane properties by different mechanisms and reduces the permeability to administered substances. These findings may help to optimize therapeutic implications.

  16. Treatment of oil sands process-affected water (OSPW) using a membrane bioreactor with a submerged flat-sheet ceramic microfiltration membrane.

    Science.gov (United States)

    Xue, Jinkai; Zhang, Yanyan; Liu, Yang; Gamal El-Din, Mohamed

    2016-01-01

    The release of oil sands process-affected water (OSPW) into the environment is a concern because it contains persistent organic pollutants that are toxic to aquatic life. A modified Ludzack-Ettinger membrane bioreactor (MLE-MBR) with a submerged ceramic membrane was continuously operated for 425 days to evaluate its feasibility on OSPW treatment. A stabilized biomass concentration of 3730 mg mixed liquor volatile suspended solids per litre and a naphthenic acid (NA) removal of 24.7% were observed in the reactor after 361 days of operation. Ultra Performance Liquid Chromatography/High Resolution Mass Spectrometry analysis revealed that the removal of individual NA species declined with increased ring numbers. Pyrosequencing analysis revealed that Betaproteobacteria were dominant in sludge samples from the MLE-MBR, with microorganisms such as Rhodocyclales and Sphingobacteriales capable of degrading hydrocarbon and aromatic compounds. During 425 days of continuous operation, no severe membrane fouling was observed as the transmembrane pressure (TMP) of the MLE-MBR never exceeded -20 kPa given that the manufacturer's suggested critical TMP for chemical cleaning is -35 kPa. Our results indicated that the proposed MLE-MBR has a good potential for removing recalcitrant organics in OSPW. PMID:26454665

  17. Nanosecond electric pulses affect a plant-specific kinesin at the plasma membrane.

    Science.gov (United States)

    Kühn, Sebastian; Liu, Qiong; Eing, Christian; Frey, Wolfgang; Nick, Peter

    2013-12-01

    Electric pulses with high field strength and durations in the nanosecond range (nsPEFs) are of considerable interest for biotechnological and medical applications. However, their actual cellular site of action is still under debate--due to their extremely short rise times, nsPEFs are thought to act mainly in the cell interior rather than at the plasma membrane. On the other hand, nsPEFs can induce membrane permeability. We have revisited this issue using plant cells as a model. By mapping the cellular responses to nsPEFs of different field strength and duration in the tobacco BY-2 cell line, we could define a treatment that does not impinge on short-term viability, such that the physiological responses to the treatment can be followed. We observe, for these conditions, a mild disintegration of the cytoskeleton, impaired membrane localization of the PIN1 auxin-efflux transporter and a delayed premitotic nuclear positioning followed by a transient mitotic arrest. To address the target site of nsPEFs, we made use of the plant-specific KCH kinesin, which can assume two different states with different localization (either near the nucleus or at the cell membrane) driving different cellular functions. We show that nsPEFs reduce cell expansion in nontransformed cells but promote expansion in a line overexpressing KCH. Since cell elongation and cell widening are linked to the KCH localized at the cell membrane, the inverted response in the KCH overexpressor provides evidence for a direct action of nsPEFs, also at the cell membrane. PMID:24062185

  18. Filtration through nylon membranes negatively affects analysis of arsenic and phosphate by the molybdenum blue method

    DEFF Research Database (Denmark)

    Heimann, Axel Colin; Jakobsen, Rasmus

    2007-01-01

    Filtering synthetic arsenic- or phosphate-containing solutions (1.5-47.6 mu mol/L) with nylon syringe filters significantly reduced absorbances (by 6-74%) when analyzed with the colorimetric molybdenum blue method. Filtering the same solutions with cellulose acetate syringe filters yielded...... no significant differences as compared to unfiltered controls. The detrimental effect of nylon membranes was also observed when pure Milli-Q water was filtered and Subsequently spiked with arsenic(III) or phosphate suggesting that some compound(s) eluting from the filter membranes interfere with the color...

  19. Divorcing folding from function: how acylation affects the membrane-perturbing properties of an antimicrobial peptide

    DEFF Research Database (Denmark)

    Vad, Brian Stougaard; Thomsen, Line Aagot Hede; Bertelsen, Kresten;

    2010-01-01

    Many small cationic peptides, which are unstructured in aqueous solution, have antimicrobial properties. These properties are assumed to be linked to their ability to permeabilize bacterial membranes, accompanied by the transition to an alpha-helical folding state. Here we show that there is no...

  20. Factors affecting alcohol-water pervaporation performance of hydrophobic zeolite-silicone rubber mixed matrix membranes

    Science.gov (United States)

    Mixed matrix membranes (MMMs) consisting of ZSM-5 zeolite particles dispersed in silicone rubber exhibited ethanol-water pervaporation permselectivities up to 5 times that of silicone rubber alone and 3 times higher than simple vapor-liquid equilibrium (VLE). A number of conditi...

  1. Even a Chronic Mild Hyperglycemia Affects Membrane Fluidity and Lipoperoxidation in Placental Mitochondria in Wistar Rats

    Science.gov (United States)

    Figueroa-García, María del Consuelo; Espinosa-García, María Teresa; Martinez-Montes, Federico; Palomar-Morales, Martín; Mejía-Zepeda, Ricardo

    2015-01-01

    It is known the deleterious effects of diabetes on embryos, but the effects of diabetes on placenta and its mitochondria are still not well known. In this work we generated a mild hyperglycemia model in female wistar rats by intraperitoneal injection of streptozotocin in 48 hours-old rats. The sexual maturity onset of the female rats was delayed around 6–7 weeks and at 16 weeks-old they were mated, and sacrificed at day 19th of pregnancy. In placental total tissue and isolated mitochondria, the fatty acids composition was analyzed by gas chromatography, and lipoperoxidation was measured by thiobarbituric acid reactive substances. Membrane fluidity in mitochondria was measured with the excimer forming probe dipyrenylpropane and mitochondrial function was measured with a Clark-type electrode. The results show that even a chronic mild hyperglycemia increases lipoperoxidation and decreases mitochondrial function in placenta. Simultaneously, placental fatty acids metabolism in total tissue is modified but in a different way than in placental mitochondria. Whereas the chronic mild hyperglycemia induced a decrease in unsaturated to saturated fatty acids ratio (U/S) in placental total tissue, the ratio increased in placental mitochondria. The measurements of membrane fluidity showed that fluidity of placenta mitochondrial membranes increased with hyperglycemia, showing consistency with the fatty acids composition through the U/S index. The thermotropic characteristics of mitochondrial membranes were changed, showing lower transition temperature and activation energies. All of these data together demonstrate that even a chronic mild hyperglycemia during pregnancy of early reproductive Wistar rats, generates an increment of lipoperoxidation, an increase of placental mitochondrial membrane fluidity apparently derived from changes in fatty acids composition and consequently, mitochondrial malfunction. PMID:26630275

  2. Nature of sterols affects plasma membrane behavior and yeast survival during dehydration.

    OpenAIRE

    Dupont, Sébastien; Beney, Laurent; Ferreira, Thierry; Gervais, Patrick

    2011-01-01

    The plasma membrane (PM) is a main site of injury during osmotic perturbation. Sterols, major lipids of the PM structure in eukaryotes, are thought to play a role in ensuring the stability of the lipid bilayer during physicochemical perturbations. Here, we investigated the relationship between the nature of PM sterols and resistance of the yeast Saccharomyces cerevisiae to hyperosmotic treatment. We compared the responses to osmotic dehydration (viability, sterol quantification, ultrastructur...

  3. Fabrication variables affecting the structure and properties of supported carbon molecular sieve membranes for hydrogen separation

    KAUST Repository

    Briceño, Kelly

    2012-10-01

    A high molecular weight polyimide (Matrimid) was used as a precursor for fabricating supported carbon molecular sieve membranes without crack formation at 550-700°C pyrolysis temperature. A one-step polymer (polyimide) coating method as precursor of carbon layer was used without needing a prior modification of a TiO 2 macroporous support. The following fabrication variables were optimized and studied to determine their effect on the carbon structure: polymeric solution concentration, solvent extraction, heating rate and pyrolysis temperature. Two techniques (Thermogravimetric analysis and Raman spectroscopy) were used to determine these effects on final carbon structure. Likewise, the effect of the support was also reported as an additional and important variable in the design of supported carbon membranes. Atomic force microscopy and differential scanning calorimetry quantified the degree of influence. Pure gas permeation tests were performed using CH 4, CO, CO 2 and H 2. The presence of a molecular sieving mechanism was confirmed after defects were plugged with PDMS solution at 12wt%. Gas selectivities higher than Knudsen theoretical values were reached with membranes obtained over 650°C, showing as best values 4.46, 4.70 and 10.62 for H 2/N 2, H 2/CO and H 2/CH 4 ratio, respectively. Permeance values were over 9.82×10 -9mol/(m 2Pas)during pure hydrogen permeation tests. © 2012 Elsevier B.V.

  4. Calcium and protons affect the interaction of neurotransmitters and anesthetics with anionic lipid membranes.

    Science.gov (United States)

    Pérez-Isidoro, Rosendo; Ruiz-Suárez, J C

    2016-09-01

    We study how zwitterionic and anionic biomembrane models interact with neurotransmitters (NTs) and anesthetics (ATs) in the presence of Ca(2+) and different pH conditions. As NTs we used acetylcholine (ACh), γ-aminobutyric acid (GABA), and l-glutamic acid (LGlu). As ATs, tetracaine (TC), and pentobarbital (PB) were employed. By using differential scanning calorimetry (DSC), we analyzed the changes such molecules produce in the thermal properties of the membranes. We found that calcium and pH play important roles in the interactions of NTs and ATs with the anionic lipid membranes. Changes in pH promote deprotonation of the phosphate groups in anionic phospholipids inducing electrostatic interactions between them and NTs; but if Ca(2+) ions are in the system, these act as bridges. Such interactions impact the physical properties of the membranes in a similar manner that anesthetics do. Beyond the usual biochemical approach, we claim that these effects should be taken into account to understand the excitatory-inhibitory orchestrated balance in the nervous system. PMID:27362370

  5. Drug membrane transporters and CYP3A4 are affected by hypericin, hyperforin or aristoforin in colon adenocarcinoma cells.

    Science.gov (United States)

    Šemeláková, M; Jendželovský, R; Fedoročko, P

    2016-07-01

    Our previous results have shown that the combination of hypericin-mediated photodynamic therapy (HY-PDT) at sub-optimal dose with hyperforin (HP) (compounds of Hypericum sp.), or its stable derivative aristoforin (AR) stimulates generation of reactive oxygen species (ROS) leading to antitumour activity. This enhanced oxidative stress evoked the need for an explanation for HY accumulation in colon cancer cells pretreated with HP or AR. Generally, the therapeutic efficacy of chemotherapeutics is limited by drug resistance related to the overexpression of drug efflux transporters in tumour cells. Therefore, the impact of non-activated hypericin (HY), HY-PDT, HP and AR on cell membrane transporter systems (Multidrug resistance-associated protein 1-MRP1/ABCC1, Multidrug resistance-associated protein 2-MRP2/ABCC2, Breast cancer resistance protein - BCRP/ABCG2, P-glycoprotein-P-gp/ABCC1) and cytochrome P450 3A4 (CYP3A4) was evaluated. The different effects of the three compounds on their expression, protein level and activity was determined under specific PDT light (T0+, T6+) or dark conditions (T0- T6-). We found that HP or AR treatment affected the protein levels of MRP2 and P-gp, whereas HP decreased MRP2 and P-gp expression mostly in the T0+ and T6+ conditions, while AR decreased MRP2 in T0- and T6+. Moreover, HY-PDT treatment induced the expression of MRP1. Our data demonstrate that HP or AR treatment in light or dark PDT conditions had an inhibitory effect on the activity of individual membrane transport proteins and significantly decreased CYP3A4 activity in HT-29 cells. We found that HP or AR significantly affected intracellular accumulation of HY in HT-29 colon adenocarcinoma cells. These results suggest that HY, HP and AR might affect the efficiency of anti-cancer drugs, through interaction with membrane transporters and CYP3A4. PMID:27261575

  6. 不同因素对离子膜电解槽电压的影响%Review of factors affecting cell voltage of ion membrane electrolyser

    Institute of Scientific and Technical Information of China (English)

    刘存玉

    2015-01-01

    Different factors affecting cell voltage of ion membrane electrolyser were summarized ,including membrane,electrolyte and its impurities,anode and cathode etc.%概述了离子膜、电解液及其杂质、阴阳极等不同因素对离子膜电解槽电压的影响。

  7. The Evolutionarily Conserved Protein PHOTOSYNTHESIS AFFECTED MUTANT71 Is Required for Efficient Manganese Uptake at the Thylakoid Membrane in Arabidopsis.

    Science.gov (United States)

    Schneider, Anja; Steinberger, Iris; Herdean, Andrei; Gandini, Chiara; Eisenhut, Marion; Kurz, Samantha; Morper, Anna; Hoecker, Natalie; Rühle, Thilo; Labs, Mathias; Flügge, Ulf-Ingo; Geimer, Stefan; Schmidt, Sidsel Birkelund; Husted, Søren; Weber, Andreas P M; Spetea, Cornelia; Leister, Dario

    2016-04-01

    In plants, algae, and cyanobacteria, photosystem II (PSII) catalyzes the light-driven oxidation of water. The oxygen-evolving complex of PSII is a Mn4CaO5 cluster embedded in a well-defined protein environment in the thylakoid membrane. However, transport of manganese and calcium into the thylakoid lumen remains poorly understood. Here, we show that Arabidopsis thaliana PHOTOSYNTHESIS AFFECTED MUTANT71 (PAM71) is an integral thylakoid membrane protein involved in Mn(2+) and Ca(2+) homeostasis in chloroplasts. This protein is required for normal operation of the oxygen-evolving complex (as evidenced by oxygen evolution rates) and for manganese incorporation. Manganese binding to PSII was severely reduced in pam71 thylakoids, particularly in PSII supercomplexes. In cation partitioning assays with intact chloroplasts, Mn(2+) and Ca(2+) ions were differently sequestered in pam71, with Ca(2+) enriched in pam71 thylakoids relative to the wild type. The changes in Ca(2+) homeostasis were accompanied by an increased contribution of the transmembrane electrical potential to the proton motive force across the thylakoid membrane. PSII activity in pam71 plants and the corresponding Chlamydomonas reinhardtii mutant cgld1 was restored by supplementation with Mn(2+), but not Ca(2+) Furthermore, PAM71 suppressed the Mn(2+)-sensitive phenotype of the yeast mutant Δpmr1 Therefore, PAM71 presumably functions in Mn(2+) uptake into thylakoids to ensure optimal PSII performance. PMID:27020959

  8. Glucosylceramide synthesis inhibition affects cell cycle progression, membrane trafficking, and stage differentiation in Giardia lamblia.

    Science.gov (United States)

    Stefanić, Sasa; Spycher, Cornelia; Morf, Laura; Fabriàs, Gemma; Casas, Josefina; Schraner, Elisabeth; Wild, Peter; Hehl, Adrian B; Sonda, Sabrina

    2010-09-01

    Synthesis of glucosylceramide via glucosylceramide synthase (GCS) is a crucial event in higher eukaryotes, both for the production of complex glycosphingolipids and for regulating cellular levels of ceramide, a potent antiproliferative second messenger. In this study, we explored the dependence of the early branching eukaryote Giardia lamblia on GCS activity. Biochemical analyses revealed that the parasite has a GCS located in endoplasmic reticulum (ER) membranes that is active in proliferating and encysting trophozoites. Pharmacological inhibition of GCS induced aberrant cell division, characterized by arrest of cytokinesis, incomplete cleavage furrow formation, and consequent block of replication. Importantly, we showed that increased ceramide levels were responsible for the cytokinesis arrest. In addition, GCS inhibition resulted in prominent ultrastructural abnormalities, including accumulation of cytosolic vesicles, enlarged lysosomes, and clathrin disorganization. Moreover, anterograde trafficking of the encystations-specific protein CWP1 was severely compromised and resulted in inhibition of stage differentiation. Our results reveal novel aspects of lipid metabolism in G. lamblia and specifically highlight the vital role of GCS in regulating cell cycle progression, membrane trafficking events, and stage differentiation in this parasite. In addition, we identified ceramide as a potent bioactive molecule, underscoring the universal conservation of ceramide signaling in eukaryotes. PMID:20335568

  9. Static Magnetic Field Attenuates Lipopolysaccharide-Induced Inflammation in Pulp Cells by Affecting Cell Membrane Stability

    Directory of Open Access Journals (Sweden)

    Sung-Chih Hsieh

    2015-01-01

    Full Text Available One of the causes of dental pulpitis is lipopolysaccharide- (LPS- induced inflammatory response. Following pulp tissue inflammation, odontoblasts, dental pulp cells (DPCs, and dental pulp stem cells (DPSCs will activate and repair damaged tissue to maintain homeostasis. However, when LPS infection is too serious, dental repair is impossible and disease may progress to irreversible pulpitis. Therefore, the aim of this study was to examine whether static magnetic field (SMF can attenuate inflammatory response of dental pulp cells challenged with LPS. In methodology, dental pulp cells were isolated from extracted teeth. The population of DPSCs in the cultured DPCs was identified by phenotypes and multilineage differentiation. The effects of 0.4 T SMF on DPCs were observed through MTT assay and fluorescent anisotropy assay. Our results showed that the SMF exposure had no effect on surface markers or multilineage differentiation capability. However, SMF exposure increases cell viability by 15%. In addition, SMF increased cell membrane rigidity which is directly related to higher fluorescent anisotropy. In the LPS-challenged condition, DPCs treated with SMF demonstrated a higher tolerance to LPS-induced inflammatory response when compared to untreated controls. According to these results, we suggest that 0.4 T SMF attenuates LPS-induced inflammatory response to DPCs by changing cell membrane stability.

  10. Printing low-voltage dielectric elastomer actuators

    Science.gov (United States)

    Poulin, Alexandre; Rosset, Samuel; Shea, Herbert R.

    2015-12-01

    We demonstrate the fabrication of fully printed thin dielectric elastomer actuators (DEAs), reducing the operation voltage below 300 V while keeping good actuation strain. DEAs are soft actuators capable of strains greater than 100% and response times below 1 ms, but they require driving voltage in the kV range, limiting the possible applications. One way to reduce the driving voltage of DEAs is to decrease the dielectric membrane thickness, which is typically in the 20-100 μm range, as reliable fabrication becomes challenging below this thickness. We report here the use of pad-printing to produce μm thick silicone membranes, on which we pad-print μm thick compliant electrodes to create DEAs. We achieve a lateral actuation strain of 7.5% at only 245 V on a 3 μm thick pad-printed membrane. This corresponds to a ratio of 125%/kV2, by far the highest reported value for DEAs. To quantify the increasing stiffening impact of the electrodes on DEA performance as the membrane thickness decreases, we compare two circular actuators, one with 3 μm- and one with 30 μm-thick membranes. Our experimental measurements show that the strain uniformity of the 3 μm-DEA is indeed affected by the mechanical impact of the electrodes. We developed a simple DEA model that includes realistic electrodes of finite stiffness, rather than assuming zero stiffness electrodes as is commonly done. The simulation results confirm that the stiffening impact of the electrodes is an important parameter that should not be neglected in the design of thin-DEAs. This work presents a practical approach towards low-voltage DEAs, a critical step for the development of real world applications.

  11. Lipid emulsions differentially affect LPS-induced acute monocytes inflammation: in vitro effects on membrane remodeling and cell viability.

    Science.gov (United States)

    Boisramé-Helms, Julie; Delabranche, Xavier; Klymchenko, Andrey; Drai, Jocelyne; Blond, Emilie; Zobairi, Fatiha; Mely, Yves; Hasselmann, Michel; Toti, Florence; Meziani, Ferhat

    2014-11-01

    The aim of this study was to assess how lipid emulsions for parenteral nutrition affect lipopolysaccharide (LPS)-induced acute monocyte inflammation in vitro. An 18 h long LPS induced human monocyte leukemia cell stimulation was performed and the cell-growth medium was supplemented with three different industrial lipid emulsions: Intralipid(®), containing long-chain triglycerides (LCT--soybean oil); Medialipid(®), containing LCT (soybean oil) and medium-chain triglycerides (MCT--coconut oil); and SMOFlipid(®), containing LCT, MCT, omega-9 and -3 (soybean, coconut, olive and fish oils). Cell viability and apoptosis were assessed by Trypan blue exclusion and flow cytometry respectively. Monocyte composition and membrane remodeling were studied using gas chromatography and NR12S staining. Microparticles released in supernatant were measured by prothrombinase assay. After LPS challenge, both cellular necrosis and apoptosis were increased (threefold and twofold respectively) and microparticle release was enhanced (sevenfold) after supplementation with Medialipid(®) compared to Intralipid(®), SMOFlipid(®) and monocytes in the standard medium. The monocytes differentially incorporated fatty acids after lipid emulsion challenge. Finally, lipid-treated cells displayed microparticles characterized by disrupted membrane lipid order, reflecting lipid remodeling of the parental cell plasma membrane. Our data suggest that lipid emulsions differentially alter cell viability, monocyte composition and thereby microparticle release. While MCT have deleterious effects, we have shown that parenteral nutrition emulsion containing LCT or LCT and MCT associated to n-3 and n-9 fatty acids have no effect on endotoxin-induced cell death and inflammation. PMID:25038627

  12. Effects of heavy metal on dielectric properties of E.coli revealed by dielectric spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Bai Wei; Zhao Kongshuang

    2006-01-01

    Dielectric spectroscopy of E.coli cell before and after exposure to heavy metals Cd2+,Cu2+, Zn2+ and Ca2+ was investigated. The results indicate that changes in dielectric spectra reflect effects of heavy metal on the structure and function of E.coli cells. Heavy metal can change membrane capacitance as well as permittivity and conductivity of the cytoplasm. Changes in volume fraction suggested that dielectric measurement could monitor the growth of E.coli cells. These results demonstrated that dielectric spectroscopy was a potential effective technique for studying electric properties of biological cells.

  13. Plasma membrane lipid–protein interactions affect signaling processes in sterol-biosynthesis mutants in Arabidopsis thaliana

    OpenAIRE

    Zauber, Henrik; Burgos, Asdrubal; Garapati, Prashanth; Schulze, Waltraud X.

    2014-01-01

    The plasma membrane is an important organelle providing structure, signaling and transport as major biological functions. Being composed of lipids and proteins with different physicochemical properties, the biological functions of membranes depend on specific protein-protein and protein-lipid interactions. Interactions of proteins with their specific sterol and lipid environment were shown to be important factors for protein recruitment into sub-compartmental structures of the plasma membrane...

  14. Activity of retinene palmitasynthetase and retinene palmitatehydrolase in the small intestine mucosa and membranes of its cells in white rats affected by A-avitaminosis and irradiation

    International Nuclear Information System (INIS)

    A combined action of A-avitaminosis and ionizing radiation on the activity of retinenepalmitatesynthetase and retinenepalmitatehydrolase in the small intestine mucosa and cell membranes of white rats has been investigated. The activity of retinenepalmitatehydrolase has been shown to decrease in the irradiated animals deficient in vitamin A as compared to the control nonirradiated animals. The activity of retinenepalmitatesynthetase affected by a combination of A-avitaminosis and irradiation increases as compared to the control nonirradiated rats both in the small intestine mucosa and its cell membranes

  15. Mutations in BIN1 Associated with Centronuclear Myopathy Disrupt Membrane Remodeling by Affecting Protein Density and Oligomerization

    Science.gov (United States)

    Wu, Tingting; Shi, Zheng; Baumgart, Tobias

    2014-01-01

    The regulation of membrane shapes is central to many cellular phenomena. Bin/Amphiphysin/Rvs (BAR) domain-containing proteins are key players for membrane remodeling during endocytosis, cell migration, and endosomal sorting. BIN1, which contains an N-BAR domain, is assumed to be essential for biogenesis of plasma membrane invaginations (T-tubules) in muscle tissues. Three mutations, K35N, D151N and R154Q, have been discovered so far in the BAR domain of BIN1 in patients with centronuclear myopathy (CNM), where impaired organization of T-tubules has been reported. However, molecular mechanisms behind this malfunction have remained elusive. None of the BIN1 disease mutants displayed a significantly compromised curvature sensing ability. However, two mutants showed impaired membrane tubulation both in vivo and in vitro, and displayed characteristically different behaviors. R154Q generated smaller membrane curvature compared to WT N-BAR. Quantification of protein density on membranes revealed a lower membrane-bound density for R154Q compared to WT and the other mutants, which appeared to be the primary reason for the observation of impaired deformation capacity. The D151N mutant was unable to tubulate liposomes under certain experimental conditions. At medium protein concentrations we found ‘budding’ structures on liposomes that we hypothesized to be intermediates during the tubulation process except for the D151N mutant. Chemical crosslinking assays suggested that the D151N mutation impaired protein oligomerization upon membrane binding. Although we found an insignificant difference between WT and K35N N-BAR in in vitro assays, depolymerizing actin in live cells allowed tubulation of plasma membranes through the K35N mutant. Our results provide insights into the membrane-involved pathophysiological mechanisms leading to human disease. PMID:24755653

  16. Electroelastic coupling between membrane surface fluctuations and membrane-embedded charges: Continuum multidielectric treatment

    Science.gov (United States)

    Miloshevsky, Gennady V.; Hassanein, Ahmed; Partenskii, Michael B.; Jordan, Peter C.

    2010-06-01

    The coupling of electric fields and charges with membrane-water interfacial fluctuations affects membrane electroporation, ionic conductance, and voltage gating. A modified continuum model is introduced to study charge interaction with membrane-water interfacial fluctuations in multidielectric environments. By surrounding a point charge with a low dielectric sphere, the linear Poisson-Boltzmann equation is directly solved by calculating the reaction field potential via a method that eliminates singularity contributions. This allows treatment of charges located at dielectric boundaries. Two complementary mechanisms governing charge-fluctuation interactions are considered: (1) electroelastic deformation (EED), treating the membrane as an elastic slab (smectic bilayer model), and (2) electrohydrophobic solvation (EHS), accounting for water penetration into the membrane's hydrophobic core. EED often leads to large membrane thickness perturbations, far larger than those consistent with elastic model descriptions [M. B. Partenskii, G. V. Miloshevsky, and P. C. Jordan, Isr. J. Chem. 47, 385 (2007)]. We argue that a switch from EED to EHS can be energetically advantageous at intermediate perturbation amplitudes. Both perturbation mechanisms are simulated by introducing adjustable shapes optimized by the kinetic Monte Carlo reaction path following approach [G. V. Miloshevsky and P. C. Jordan, J. Chem. Phys. 122, 214901 (2005)]. The resulting energy profiles agree with those of recent atomistic molecular dynamics studies on translating a charged residue across a lipid bilayer [S. Dorairaj and T. W. Allen, Proc. Natl. Acad. Sci. U.S.A. 104, 4943 (2007)].

  17. Changes in the Sterol Composition of the Plasma Membrane Affect Membrane Potential, Salt Tolerance and the Activity of Multidrug Resistance Pumps in Saccharomyces cerevisiae

    Czech Academy of Sciences Publication Activity Database

    Kodedová, Marie; Sychrová, Hana

    2015-01-01

    Roč. 10, č. 9 (2015), e0139306. E-ISSN 1932-6203 R&D Projects: GA MŠk(CZ) EE2.3.30.0025; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:67985823 Keywords : Saccharomyces cerevisiae * ergosterol synthesis * multidrug resistance * membrane potential * diS-C3(3) assay Subject RIV: EE - Microbiology, Virology Impact factor: 3.234, year: 2014

  18. Imp2, the PSTPIP homolog in fission yeast, affects sensitivity to the immunosuppressant FK506 and membrane trafficking in fission yeast

    Energy Technology Data Exchange (ETDEWEB)

    Kita, Ayako; Higa, Mari [Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502 (Japan); Doi, Akira [Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502 (Japan); Japan Society for the Promotion of Science, 1-8 Chiyoda-ku, Tokyo 102-8472 (Japan); Satoh, Ryosuke [Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502 (Japan); Sugiura, Reiko, E-mail: sugiurar@phar.kindai.ac.jp [Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, 3-4-1 Kowakae, Higashi-Osaka 577-8502 (Japan)

    2015-02-13

    Cytokinesis is a highly ordered process that divides one cell into two cells, which is functionally linked to the dynamic remodeling of the plasma membrane coordinately with various events such as membrane trafficking. Calcineurin is a highly conserved serine/threonine protein phosphatase, which regulates multiple biological functions, such as membrane trafficking and cytokinesis. Here, we isolated imp2-c3, a mutant allele of the imp2{sup +} gene, encoding a homolog of the mouse PSTPIP1 (proline-serine-threonine phosphatase interacting protein 1), using a genetic screen for mutations that are synthetically lethal with calcineurin deletion in fission yeast. The imp2-c3 mutants showed a defect in cytokinesis with multi-septated phenotypes, which was further enhanced upon treatment with the calcineurin inhibitor FK506. Notably, electron micrographs revealed that the imp2-c3 mutant cells accumulated aberrant multi-lamella Golgi structures and putative post-Golgi secretory vesicles, and exhibited fragmented vacuoles in addition to thickened septa. Consistently, imp2-c3 mutants showed a reduced secretion of acid phosphatase and defects in vacuole fusion. The imp2-c3 mutant cells exhibited a weakened cell wall, similar to the membrane trafficking mutants identified in the same genetic screen such as ypt3-i5. These findings implicate the PSTPIP1 homolog Imp2 in Golgi/vacuole function, thereby affecting various cellular processes, including cytokinesis and cell integrity. - Highlights: • We isolated imp2-c3, in a synthetic lethal screen with calcineurin in fission yeast. • The imp2{sup +} gene encodes a component of the actin contractile ring similar to Cdc15. • The imp2-c3 mutants showed defects in cytokinesis, which were exacerbated by FK506. • The imp2-c3 mutants were defective in membrane trafficking and cell wall integrity. • Our study revealed a novel role for Imp2 in the Golgi/vacuolar membrane trafficking.

  19. Imp2, the PSTPIP homolog in fission yeast, affects sensitivity to the immunosuppressant FK506 and membrane trafficking in fission yeast

    International Nuclear Information System (INIS)

    Cytokinesis is a highly ordered process that divides one cell into two cells, which is functionally linked to the dynamic remodeling of the plasma membrane coordinately with various events such as membrane trafficking. Calcineurin is a highly conserved serine/threonine protein phosphatase, which regulates multiple biological functions, such as membrane trafficking and cytokinesis. Here, we isolated imp2-c3, a mutant allele of the imp2+ gene, encoding a homolog of the mouse PSTPIP1 (proline-serine-threonine phosphatase interacting protein 1), using a genetic screen for mutations that are synthetically lethal with calcineurin deletion in fission yeast. The imp2-c3 mutants showed a defect in cytokinesis with multi-septated phenotypes, which was further enhanced upon treatment with the calcineurin inhibitor FK506. Notably, electron micrographs revealed that the imp2-c3 mutant cells accumulated aberrant multi-lamella Golgi structures and putative post-Golgi secretory vesicles, and exhibited fragmented vacuoles in addition to thickened septa. Consistently, imp2-c3 mutants showed a reduced secretion of acid phosphatase and defects in vacuole fusion. The imp2-c3 mutant cells exhibited a weakened cell wall, similar to the membrane trafficking mutants identified in the same genetic screen such as ypt3-i5. These findings implicate the PSTPIP1 homolog Imp2 in Golgi/vacuole function, thereby affecting various cellular processes, including cytokinesis and cell integrity. - Highlights: • We isolated imp2-c3, in a synthetic lethal screen with calcineurin in fission yeast. • The imp2+ gene encodes a component of the actin contractile ring similar to Cdc15. • The imp2-c3 mutants showed defects in cytokinesis, which were exacerbated by FK506. • The imp2-c3 mutants were defective in membrane trafficking and cell wall integrity. • Our study revealed a novel role for Imp2 in the Golgi/vacuolar membrane trafficking

  20. The N370S (Asn370-->Ser) mutation affects the capacity of glucosylceramidase to interact with anionic phospholipid-containing membranes and saposin C.

    Science.gov (United States)

    Salvioli, Rosa; Tatti, Massimo; Scarpa, Susanna; Moavero, Sabrina Maria; Ciaffoni, Fiorella; Felicetti, Federica; Kaneski, Christine R; Brady, Roscoe O; Vaccaro, Anna Maria

    2005-08-15

    The properties of the endolysosomal enzyme GCase (glucosylceramidase), carrying the most prevalent mutation observed in Gaucher patients, namely substitution of an asparagine residue with a serine at amino acid position 370 [N370S (Asn370-->Ser) GCase], were investigated in the present study. We previously demonstrated that Sap (saposin) C, the physiological GCase activator, promotes the association of GCase with anionic phospholipid-containing membranes, reconstituting in this way the enzyme activity. In the present study, we show that, in the presence of Sap C and membranes containing high levels of anionic phospholipids, both normal and N370S GCases are able to associate with the lipid surface and to express their activity. Conversely, when the amount of anionic phospholipids in the membrane is reduced (approximately 20% of total lipids), Sap C is still able to promote binding and activation of the normal enzyme, but not of N370S GCase. The altered interaction of the mutated enzyme with anionic phospholipid-containing membranes and Sap C was further demonstrated in Gaucher fibroblasts by confocal microscopy, which revealed poor co-localization of N370S GCase with Sap C and lysobisphosphatidic acid, the most abundant anionic phospholipid in endolysosomes. Moreover, we found that N370S Gaucher fibroblasts accumulate endolysosomal free cholesterol, a lipid that might further interfere with the interaction of the enzyme with Sap C and lysobisphosphatidic acid-containing membranes. In summary, our results show that the N370S mutation primarily affects the interaction of GCase with its physiological activators, namely Sap C and anionic phospholipid-containing membranes. We thus propose that the poor contact between N370S GCase and its activators may be responsible for the low activity of the mutant enzyme in vivo. PMID:15826241

  1. Electroelastic coupling between membrane surface fluctuations and membrane-embedded charges: Continuum multidielectric treatment

    Energy Technology Data Exchange (ETDEWEB)

    Miloshevsky, Gennady V., E-mail: gennady@purdue.edu; Hassanein, Ahmed, E-mail: hassanein@purdue.edu [School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Partenskii, Michael B., E-mail: partensky@gmail.com; Jordan, Peter C., E-mail: jordan@brandeis.edu [Department of Chemistry, MS-015, Brandeis University, P.O. Box 549110, Waltham, Massachusetts 02454-9110 (United States)

    2010-06-21

    The coupling of electric fields and charges with membrane-water interfacial fluctuations affects membrane electroporation, ionic conductance, and voltage gating. A modified continuum model is introduced to study charge interaction with membrane-water interfacial fluctuations in multidielectric environments. By surrounding a point charge with a low dielectric sphere, the linear Poisson–Boltzmann equation is directly solved by calculating the reaction field potential via a method that eliminates singularity contributions. This allows treatment of charges located at dielectric boundaries. Two complementary mechanisms governing charge-fluctuation interactions are considered: (1) electroelastic deformation (EED), treating the membrane as an elastic slab (smectic bilayer model), and (2) electrohydrophobic solvation (EHS), accounting for water penetration into the membrane’s hydrophobic core. EED often leads to large membrane thickness perturbations, far larger than those consistent with elastic model descriptions [M. B. Partenskii, G. V. Miloshevsky, and P. C. Jordan, Isr. J. Chem. 47, 385 (2007)]. We argue that a switch from EED to EHS can be energetically advantageous at intermediate perturbation amplitudes. Both perturbation mechanisms are simulated by introducing adjustable shapes optimized by the kinetic Monte Carlo reaction path following approach [G. V. Miloshevsky and P. C. Jordan, J. Chem. Phys. 122, 214901 (2005)]. The resulting energy profiles agree with those of recent atomistic molecular dynamics studies on translating a charged residue across a lipid bilayer [S. Dorairaj and T. W. Allen, Proc. Natl. Acad. Sci. U.S.A. 104, 4943 (2007)].

  2. Electroelastic coupling between membrane surface fluctuations and membrane-embedded charges: Continuum multidielectric treatment

    International Nuclear Information System (INIS)

    The coupling of electric fields and charges with membrane-water interfacial fluctuations affects membrane electroporation, ionic conductance, and voltage gating. A modified continuum model is introduced to study charge interaction with membrane-water interfacial fluctuations in multidielectric environments. By surrounding a point charge with a low dielectric sphere, the linear Poisson–Boltzmann equation is directly solved by calculating the reaction field potential via a method that eliminates singularity contributions. This allows treatment of charges located at dielectric boundaries. Two complementary mechanisms governing charge-fluctuation interactions are considered: (1) electroelastic deformation (EED), treating the membrane as an elastic slab (smectic bilayer model), and (2) electrohydrophobic solvation (EHS), accounting for water penetration into the membrane’s hydrophobic core. EED often leads to large membrane thickness perturbations, far larger than those consistent with elastic model descriptions [M. B. Partenskii, G. V. Miloshevsky, and P. C. Jordan, Isr. J. Chem. 47, 385 (2007)]. We argue that a switch from EED to EHS can be energetically advantageous at intermediate perturbation amplitudes. Both perturbation mechanisms are simulated by introducing adjustable shapes optimized by the kinetic Monte Carlo reaction path following approach [G. V. Miloshevsky and P. C. Jordan, J. Chem. Phys. 122, 214901 (2005)]. The resulting energy profiles agree with those of recent atomistic molecular dynamics studies on translating a charged residue across a lipid bilayer [S. Dorairaj and T. W. Allen, Proc. Natl. Acad. Sci. U.S.A. 104, 4943 (2007)

  3. Dielectric Actuation of Polymers

    OpenAIRE

    Niu, Xiaofan

    2013-01-01

    Dielectric polymers are widely used in a plurality of applications, such as electrical insulation, dielectric capacitors, and electromechanical actuators. Dielectric polymers with large strain deformations under an electric field are named dielectric elastomers (DE), because of their relative low modulus, high elongation at break, and outstanding resilience. Dielectric elastomer actuators (DEA) are superior to traditional transducers as a muscle-like technology: large strains, high energy den...

  4. Gender and chronological age affect erythrocyte membrane oxidative indices in citrate phosphate dextrose adenine-formula 1 (CPDA-1) blood bank storage condition.

    Science.gov (United States)

    Erman, Hayriye; Aksu, Uğur; Belce, Ahmet; Atukeren, Pınar; Uzun, Duygu; Cebe, Tamer; Kansu, Ahmet D; Gelişgen, Remisa; Uslu, Ezel; Aydın, Seval; Çakatay, Ufuk

    2016-07-01

    It is well known that in vitro storage lesions lead to membrane dysfunction and decreased number of functional erythrocytes. As erythrocytes get older, in storage media as well as in peripheral circulation, they undergo a variety of biochemical changes. In our study, the erythrocytes with different age groups in citrate phosphate dextrose adenine-formula 1 (CPDA-1) storage solution were used in order to investigate the possible effect of gender factor on oxidative damage. Oxidative damage biomarkers in erythrocyte membranes such as ferric reducing antioxidant power, pro-oxidant-antioxidant balance, protein-bound advance glycation end products, and sialic acid were analyzed. Current study reveals that change in membrane redox status during blood-bank storage condition also depends on both gender depended homeostatic factors and the presence of CPDA-1. During the storage period in CPDA-1, erythrocytes from the male donors are mostly affected by free radical-mediated oxidative stress but erythrocytes obtained from females are severely affected by glyoxidative stress. PMID:27045670

  5. Increasing venoarterial extracorporeal membrane oxygenation flow negatively affects left ventricular performance in a porcine model of cardiogenic shock

    OpenAIRE

    Ostadal, Petr; Mlcek, Mikulas; Kruger, Andreas; Hala, Pavel; Lacko, Stanislav; Mates, Martin; Vondrakova, Dagmar; Svoboda, Tomas; Hrachovina, Matej; Janotka, Marek; Psotova, Hana; Strunina, Svitlana; Kittnar, Otomar; Neuzil, Petr

    2015-01-01

    Background The aim of this study was to assess the relationship between extracorporeal blood flow (EBF) and left ventricular (LV) performance during venoarterial extracorporeal membrane oxygenation (VA ECMO) therapy. Methods Five swine (body weight 45 kg) underwent VA ECMO implantation under general anesthesia and artificial ventilation. Subsequently, acute cardiogenic shock with signs of tissue hypoxia was induced. Hemodynamic and cardiac performance parameters were then measured at differen...

  6. Two Coiled-Coil Domains of Chlamydia trachomatis IncA Affect Membrane Fusion Events during Infection

    OpenAIRE

    Ronzone, Erik; Paumet, Fabienne

    2013-01-01

    Chlamydia trachomatis replicates in a parasitophorous membrane-bound compartment called an inclusion. The inclusions corrupt host vesicle trafficking networks to avoid the degradative endolysosomal pathway but promote fusion with each other in order to sustain higher bacterial loads in a process known as homotypic fusion. The Chlamydia protein IncA (Inclusion protein A) appears to play central roles in both these processes as it participates to homotypic fusion and inhibits endocytic SNARE-me...

  7. The affects of membrane on the cell performance when using alkaline borohydride-hydrazine solutions as the fuel

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Haiying; Liu, Zixuan; Guo, Yanfeng; Li, Zhoupeng [Department of Chemical and Bio-chemical Engineering, Zhejiang University, Hangzhou 310027 (China)

    2010-04-15

    The cell performance and the polarization behavior of the fuel cell using alkaline NaBH{sub 4}-N{sub 2}H{sub 4} solutions as the fuel were investigated. It was found that the use of different membrane: anion exchange membrane (AEM) or cation exchange membrane (CEM) would influence the cell performance and cathode polarization behavior. The direct borohydride fuel cell (DBFC) using CEM gave a higher power density than that using AEM, but the direct hydrazine fuel cell (DHFC) using CEM gave a lower power density compared with the DHFC using AEM. In the DBFCs using CEM, N{sub 2}H{sub 4} addition in alkaline NaBH{sub 4} solution improved the cell performance but it did not make any difference when adding more N{sub 2}H{sub 4}. On the other hand, in the DBFCs using AEM, cell performance was improved with increasing the amount of N{sub 2}H{sub 4} in the anolyte. (author)

  8. Suppression of electromechanical instability in fiber-reinforced dielectric elastomers

    Science.gov (United States)

    Xiao, Rui; Gou, Xiaofan; Chen, Wen

    2016-03-01

    The electromechanical instability of dielectric elastomers has been a major challenge for the application of this class of active materials. In this work, we demonstrate that dielectric elastomers filled with soft fiber can suppress the electromechanical instability and achieve large deformation. Specifically, we developed a constitutive model to describe the dielectric and mechanical behaviors of fiber-reinforced elastomers. The model was applied to study the influence of stiffness, nonlinearity properties and the distribution of fiber on the instability of dielectric membrane under an electric field. The results show that there exists an optimal fiber distribution condition to achieve the maximum deformation before failure.

  9. Suppression of electromechanical instability in fiber-reinforced dielectric elastomers

    Directory of Open Access Journals (Sweden)

    Rui Xiao

    2016-03-01

    Full Text Available The electromechanical instability of dielectric elastomers has been a major challenge for the application of this class of active materials. In this work, we demonstrate that dielectric elastomers filled with soft fiber can suppress the electromechanical instability and achieve large deformation. Specifically, we developed a constitutive model to describe the dielectric and mechanical behaviors of fiber-reinforced elastomers. The model was applied to study the influence of stiffness, nonlinearity properties and the distribution of fiber on the instability of dielectric membrane under an electric field. The results show that there exists an optimal fiber distribution condition to achieve the maximum deformation before failure.

  10. Glucosylceramide synthesis inhibition affects cell cycle progression, membrane trafficking, and stage differentiation in Giardia lamblia[S

    Science.gov (United States)

    Štefanić, Saša; Spycher, Cornelia; Morf, Laura; Fabriàs, Gemma; Casas, Josefina; Schraner, Elisabeth; Wild, Peter; Hehl, Adrian B.; Sonda, Sabrina

    2010-01-01

    Synthesis of glucosylceramide via glucosylceramide synthase (GCS) is a crucial event in higher eukaryotes, both for the production of complex glycosphingolipids and for regulating cellular levels of ceramide, a potent antiproliferative second messenger. In this study, we explored the dependence of the early branching eukaryote Giardia lamblia on GCS activity. Biochemical analyses revealed that the parasite has a GCS located in endoplasmic reticulum (ER) membranes that is active in proliferating and encysting trophozoites. Pharmacological inhibition of GCS induced aberrant cell division, characterized by arrest of cytokinesis, incomplete cleavage furrow formation, and consequent block of replication. Importantly, we showed that increased ceramide levels were responsible for the cytokinesis arrest. In addition, GCS inhibition resulted in prominent ultrastructural abnormalities, including accumulation of cytosolic vesicles, enlarged lysosomes, and clathrin disorganization. Moreover, anterograde trafficking of the encystations-specific protein CWP1 was severely compromised and resulted in inhibition of stage differentiation. Our results reveal novel aspects of lipid metabolism in G. lamblia and specifically highlight the vital role of GCS in regulating cell cycle progression, membrane trafficking events, and stage differentiation in this parasite. In addition, we identified ceramide as a potent bioactive molecule, underscoring the universal conservation of ceramide signaling in eukaryotes. PMID:20335568

  11. Dielectric Laser Acceleration

    OpenAIRE

    England, R. Joel; Noble, Robert J.; Wu, Ziran; Qi, Minghao

    2013-01-01

    We describe recent advances in the study of particle acceleration using dielectric near-field structures driven by infrared lasers, which we refer to as Dielectric Laser Accelerators. Implications for high energy physics and other applications are discussed.

  12. Saponins do not affect the ecdysteroid receptor complex but cause membrane permeation in insect culture cell lines.

    Science.gov (United States)

    De Geyter, Ellen; Swevers, Luc; Soin, Thomas; Geelen, Danny; Smagghe, Guy

    2012-01-01

    This project studied the effects of four saponins with a triterpenoid (Quillajasaponaria saponin and aescin) or steroid structure (digitonin and diosgenin which is the deglycosylated form of dioscin) on insect cells, namely Schneider S2 cells of Drosophila melanogaster (Diptera). A series of different experiments were performed to investigate potential mechanisms of action by saponins with regard to ecdysteroid receptor (EcR) responsiveness, cell viability, cell membrane permeation, and induction of apoptosis with DNA fragmentation and caspase-3 like activity. Major results were that (1) exposure of S2 cells containing an EcR-based reporter construct to a concentration series of each saponin scored no EcR activation, while (2) a loss of ecdysteroid signaling was observed with median inhibitory concentrations (IC(50)'s) of 3-50 μM, and in parallel (3) a concentration-dependent change in loss of cell numbers in an cell viability assay with median effective concentrations (EC(50)'s) of 8-699 μM. In continuation, it was of interest that (4) a trypan blue assay with Q. saponaria saponin confirmed the cell membrane permeation effect leading to cell toxicity with a median lethal concentration (LC(50)) value of 44 μM, and interestingly this effect was very rapid. Another three interesting observations were that (5) exposure to 20E at 500 nM as used in the EcR-based report assay induced caspase-3 like activities which may help to explain the discrepancies between loss of EcR-responsiveness and cell viability, (6) low concentrations of saponins induced DNA fragmentation and caspase-3 like activities, confirming their potential to induce apoptosis, and (7) the saponin effects were counteracted with addition of cholesterol to the culture medium. In general the data obtained provide evidence that the anti-ecdysteroid action by saponins is not based on a true antagonistic interaction with EcR signaling, but can be explained by a cytotoxic action due to permeation of the

  13. Dielectrics in electric fields

    CERN Document Server

    Raju, Gorur G

    2003-01-01

    Discover nontraditional applications of dielectric studies in this exceptionally crafted field reference or text for seniors and graduate students in power engineering tracks. This text contains more than 800 display equations and discusses polarization phenomena in dielectrics, the complex dielectric constant in an alternating electric field, dielectric relaxation and interfacial polarization, the measurement of absorption and desorption currents in time domains, and high field conduction phenomena. Dielectrics in Electric Fields is an interdisciplinary reference and text for professionals and students in electrical and electronics, chemical, biochemical, and environmental engineering; physical, surface, and colloid chemistry; materials science; and chemical physics.

  14. Dielectric modelling of erythrocyte aggregation in blood

    International Nuclear Information System (INIS)

    The dielectric spectrum of whole blood is markedly changed by aggregation of erythrocytes, the so-called rouleau formation. The dielectric behaviour has been simulated using an erythrocyte model that is a disc covered with a thin membrane and an erythrocyte aggregate model that is a pile of the discs with regular spacing ds. The effective complex permittivity of a cubic system including one of the models was calculated by a numerical technique based on the three-dimensional finite-difference method. Both the models have anisotropic dielectric properties depending on whether the rotational axis of the separate or the aggregate model is parallel (the parallel orientation) or perpendicular (the perpendicular orientation) to the direction of the applied electric field. The models both showed a single dielectric relaxation, which was different in intensity and characteristic frequency between the two orientations. For the erythrocyte aggregate model, the relaxation intensity Δε increased and the characteristic frequency fc decreased with decreasing ds in the perpendicular orientation, whereas the opposite ds-dependence was found for Δε and fc in the parallel orientation. Increasing the number of cells in the aggregate model enhanced these effects. The difference in dielectric spectrum between the separate and the aggregate models represented well the dielectric spectrum change caused by rouleau formation

  15. Lattices of dielectric resonators

    CERN Document Server

    Trubin, Alexander

    2016-01-01

    This book provides the analytical theory of complex systems composed of a large number of high-Q dielectric resonators. Spherical and cylindrical dielectric resonators with inferior and also whispering gallery oscillations allocated in various lattices are considered. A new approach to S-matrix parameter calculations based on perturbation theory of Maxwell equations, developed for a number of high-Q dielectric bodies, is introduced. All physical relationships are obtained in analytical form and are suitable for further computations. Essential attention is given to a new unified formalism of the description of scattering processes. The general scattering task for coupled eigen oscillations of the whole system of dielectric resonators is described. The equations for the  expansion coefficients are explained in an applicable way. The temporal Green functions for the dielectric resonator are presented. The scattering process of short pulses in dielectric filter structures, dielectric antennas  and lattices of d...

  16. Cadmium affects viability of bone marrow mesenchymal stem cells through membrane impairment, intracellular calcium elevation and DNA breakage

    Directory of Open Access Journals (Sweden)

    Abnosi Mohammad Hussein

    2010-01-01

    Full Text Available Background: Cadmium is an important heavy metal with occupational and environmental hazard. Cadmium toxicity results mainly in bone-related complication such as itai-itai disease. Mesenchymal stem cells of the bone marrow have the ability to differentiate to osteoblasts which ensure the well-being of the bone tissue. Thus the aim was to investigate the effect of cadmium on viability of rat bone marrow mesenchymal stem cells. Materials and Methods: The rat bone marrow mesenchymal stem cells were grown to confluency in DMEM medium supplemented with 15% fetal bovine serum and penicillin-streptomycin up to third passage. Then the cells were treated with 0, 5, 15, 25, 35, and 45 of CdCl 2 at 12, 24, 36, and 48 h, and their viability was investigated using trypan blue staining. In addition, after treatment with selected dose (15 and 45 μM and time (24 and 48 h the cell morphology, DNA damage and calcium content of the cells were evaluated. Data was analyzed using one and two-way ANOVA (Tukey test and the P2+ was observed. Conclusion: Cadmium chloride is a toxic compound which might affect the well-being of bone tissue through affecting the mesenchymal stem cells.

  17. Broadband Dielectric Spectroscopy on Human Blood

    CERN Document Server

    Wolf, M; Lunkenheimer, P; Loidl, A

    2011-01-01

    Dielectric spectra of human blood reveal a rich variety of dynamic processes. Achieving a better characterization and understanding of these processes not only is of academic interest but also of high relevance for medical applications as, e.g., the determination of absorption rates of electromagnetic radiation by the human body. The dielectric properties of human blood are studied using broadband dielectric spectroscopy, systematically investigating the dependence on temperature and hematocrit value. By covering a frequency range from 1 Hz to 40 GHz, information on all the typical dispersion regions of biological matter is obtained. We find no evidence for a low-frequency relaxation (alpha-relaxation) caused, e.g., by counterion diffusion effects as reported for some types of biological matter. The analysis of a strong Maxwell-Wagner relaxation arising from the polarization of the cell membranes in the 1-100 MHz region (beta-relaxation) allows for the test of model predictions and the determination of variou...

  18. Resonant dielectric metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Loui, Hung; Carroll, James; Clem, Paul G; Sinclair, Michael B

    2014-12-02

    A resonant dielectric metamaterial comprises a first and a second set of dielectric scattering particles (e.g., spheres) having different permittivities arranged in a cubic array. The array can be an ordered or randomized array of particles. The resonant dielectric metamaterials are low-loss 3D isotropic materials with negative permittivity and permeability. Such isotropic double negative materials offer polarization and direction independent electromagnetic wave propagation.

  19. Infrared Dielectric Resonator Metamaterial

    CERN Document Server

    Ginn, James C; Peters, David W; Wendt, Joel R; Stevens, Jeffrey O; Hines, Paul F; Basilio, Lorena I; Warne, Larry K; Ihlefeld, Jon F; Clem, Paul G; Sinclair, Michael B

    2011-01-01

    We demonstrate, for the first time, an all-dielectric metamaterial resonator in the mid-wave infrared based on high-index tellurium cubic inclusions. Dielectric resonators are desirable compared to conventional metallo-dielectric metamaterials at optical frequencies as they are largely angular invariant, free of ohmic loss, and easily integrated into three-dimensional volumes. With these low-loss, isotropic elements, disruptive optical metamaterial designs, such as wide-angle lenses and cloaks, can be more easily realized.

  20. Open-access dielectric elastomer material database

    Science.gov (United States)

    Vertechy, R.; Fontana, M.; Stiubianu, G.; Cazacu, M.

    2014-03-01

    Dielectric Elastomer Transducers (DETs) are deformable capacitors that can be used as sensors, actuators and generators. The design of effective and optimized DETs requires the knowledge of a set of relevant properties of the employed Dielectric Elastomer (DE) material, which make it possible to accurately predict their electromechanical dynamic behavior. In this context, an open-access database for DE materials has been created with the aim of providing the practicing engineer with the essential information for the design and optimization of new kinds of DET. Among the electrical properties, dielectric susceptibility, dielectric strength and conductivity are considered along with their dependence on mechanical strain. As regards mechanical behavior, experimental stress-strain curves are provided to predict hyperelasticity, plasticity, viscosity, Mullins effect and mechanical rupture. Properties of commercial elastomeric membranes have been entered in the database and made available to the research community. This paper describes the instrumentations, experimental setups and procedures that have been employed for the characterization of the considered DE materials. To provide an example, the experimental data acquired for a commercially available natural rubber membrane (OPPO Band Red 8012) are presented.

  1. Optics of dielectric microstructures

    DEFF Research Database (Denmark)

    Søndergaard, Thomas

    2002-01-01

    From the work carried out within the ph.d. project two topics have been selected for this thesis, namely emission of radiation by sources in dielectric microstructures, and planar photonic crystal waveguides. The work done within the first topic, emission of radiation by sources in dielectric mic...

  2. Terahertz Artificial Dielectric Lens

    Science.gov (United States)

    Mendis, Rajind; Nagai, Masaya; Wang, Yiqiu; Karl, Nicholas; Mittleman, Daniel M.

    2016-03-01

    We have designed, fabricated, and experimentally characterized a lens for the THz regime based on artificial dielectrics. These are man-made media that mimic properties of naturally occurring dielectric media, or even manifest properties that cannot generally occur in nature. For example, the well-known dielectric property, the refractive index, which usually has a value greater than unity, can have a value less than unity in an artificial dielectric. For our lens, the artificial-dielectric medium is made up of a parallel stack of 100 μm thick metal plates that form an array of parallel-plate waveguides. The convergent lens has a plano-concave geometry, in contrast to conventional dielectric lenses. Our results demonstrate that this lens is capable of focusing a 2 cm diameter beam to a spot size of 4 mm, at the design frequency of 0.17 THz. The results further demonstrate that the overall power transmission of the lens can be better than certain conventional dielectric lenses commonly used in the THz regime. Intriguingly, we also observe that under certain conditions, the lens boundary demarcated by the discontinuous plate edges actually resembles a smooth continuous surface. These results highlight the importance of this artificial-dielectric technology for the development of future THz-wave devices.

  3. Surface properties of dielectrics

    International Nuclear Information System (INIS)

    Importance of defects on dielectric behaviour (breakdown), mechanical behaviour (fracture, adhesion) and thermochemical behaviour of insulating materials is recalled. Then effect of a mechanical stress on breakdown voltage is studied. An experimental verification shows that fracture of Y2O3 is propagated in grain boundaries enriched in oxygen vacancies for a non stoichiometric sample by local variation of dielectric constant

  4. Microscopic dielectric permittivities of graphene nanoribbons and graphene

    Science.gov (United States)

    Fang, Jingtian; Vandenberghe, William G.; Fischetti, Massimo V.

    2016-07-01

    We derive a microscopic Poisson equation using the density-density response function. This equation is valid for any realistic potential perturbation and permits the study of dielectric response in nanostructures, especially in one-dimensional nanostructures and quantum dots. We apply this equation to simulate a nanoscale parallel-plate capacitor (nanocapacitor) with graphene as dielectric and two nanocapacitors with a graphene nanoribbon (GNR) as dielectric. The density-density response function is calculated using first-order perturbation theory and empirical pseudopotentials. From the microscopic electric field of the graphene nanocapacitor, we calculate the out-of-plane microscopic dielectric constant of graphene and from the electric field of GNR nanocapacitors, we calculate the full microscopic dielectric tensor of several GNRs with different widths. We find that the out-of-plane microscopic dielectric constants of GNRs and graphene do not depend on their energy band gap. We also study the effect of a surrounding dielectric on the dielectric permittivity of graphene and we conclude that the surrounding dielectric barely affects the dielectric permittivity of graphene.

  5. Standards for dielectric elastomer transducers

    Science.gov (United States)

    Carpi, Federico; Anderson, Iain; Bauer, Siegfried; Frediani, Gabriele; Gallone, Giuseppe; Gei, Massimiliano; Graaf, Christian; Jean-Mistral, Claire; Kaal, William; Kofod, Guggi; Kollosche, Matthias; Kornbluh, Roy; Lassen, Benny; Matysek, Marc; Michel, Silvain; Nowak, Stephan; O'Brien, Benjamin; Pei, Qibing; Pelrine, Ron; Rechenbach, Björn; Rosset, Samuel; Shea, Herbert

    2015-10-01

    Dielectric elastomer transducers consist of thin electrically insulating elastomeric membranes coated on both sides with compliant electrodes. They are a promising electromechanically active polymer technology that may be used for actuators, strain sensors, and electrical generators that harvest mechanical energy. The rapid development of this field calls for the first standards, collecting guidelines on how to assess and compare the performance of materials and devices. This paper addresses this need, presenting standardized methods for material characterisation, device testing and performance measurement. These proposed standards are intended to have a general scope and a broad applicability to different material types and device configurations. Nevertheless, they also intentionally exclude some aspects where knowledge and/or consensus in the literature were deemed to be insufficient. This is a sign of a young and vital field, whose research development is expected to benefit from this effort towards standardisation.

  6. Design of experiment study of the parameters that affect performance of three flow plate configurations of a proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Low temperature hydrogen fuel cells are electrochemical devices which offer a promising alternative to traditional power sources. Fuel cells produce electricity with a reaction of the fuel (hydrogen) and air. Fuel cells have the advantage of being clean; only producing water and heat as by products. The efficiency of a fuel cell varies depending on the type; SOFC with CHP for example, can have a system efficiency of up to 65%. What the Authors present here is a comparison between three different configurations of flow plates of a proton exchange membrane fuel cell, the manufacturer's serpentine flow plate and two new configurations; the maze flow plate and the parallel flow plate. A study of the input parameters affecting output responses of voltage, current, power and efficiency of a fuel cell is performed through experimentation. The results were taken from direct readings of the fuel cell and from polarisation curves produced. This information was then analysed through a design of experiment to investigate the effects of the changing parameters on different configurations of the fuel cell's flow plates. The results indicate that, in relation to current and voltage response of the polarisation curve and the corresponding graphs produced from the DOE, the serpentine flow plate design is a much more effective design than the maze or parallel flow plate design. It was noted that the parallel flow plate performed reasonably well at higher pressures but over all statically the serpentine flow plate performed better.

  7. Tunable Liquid Dielectric Antenna

    Directory of Open Access Journals (Sweden)

    Kamal Raj Singh Rajoriya

    2012-06-01

    Full Text Available This paper presents on modified the dielectric properties of liquid with varying salinity that was based on monopole structure. Dielectric resonator antennas (DRAs can be made with a wide range of materials and allow many excitation methods [2]. Pure water does not work at high frequency (> 1 GHz but increase in the salinity of water modifies the dielectric properties of water. Here proposed antenna shows that when the salinity increases in form of molar solution, the antenna was tuned at different frequency with increases return loss.

  8. Cast dielectric composite linear accelerator

    Science.gov (United States)

    Sanders, David M.; Sampayan, Stephen; Slenes, Kirk; Stoller, H. M.

    2009-11-10

    A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

  9. Noncontact Dielectric Friction

    OpenAIRE

    Kuehn, Seppe; Marohn, John A.; Loring, Roger F.

    2006-01-01

    Dielectric fluctuations are shown to be the dominant source of noncontact friction in high-sensitivity scanning probe microscopy of dielectric materials. Recent measurements have directly determined the friction acting on custom-fabricated single-crystal silicon cantilevers whose capacitively charged tips are located 3–200 nm above thin films of poly(methyl methacrylate), poly(vinyl acetate), and polystyrene. Differences in measured friction among these polymers are explained here by relating...

  10. Pattern formation in dielectric barrier discharges with different dielectric materials

    International Nuclear Information System (INIS)

    The influence of dielectric material on the bifurcation and spatiotemporal dynamics of the patterns in dielectric barrier discharge in argon/air at atmospheric pressure is studied. It is found that pattern bifurcation sequences are different with different dielectric materials. The spatiotemporal dynamics of the hexagonal pattern in dielectric barrier discharge depends on the dielectric material. The hexagon pattern with glass dielectric is an interleaving of two rectangular sublattices appearing at different moments. The hexagon pattern with quartz dielectric is composed of one set of hexagonal lattice discharging twice in one half cycle of the applied voltage, one is at the rising edge and the other at the falling edge. It results in that the accumulation of wall charges in individual microdischarges in a hexagon pattern with quartz dielectric is greater than that with glass dielectric, which is in agreement with the electron density measurement by Stark broadening of Ar I 696.54 nm.

  11. Temperature dependence of the dielectric constant of acrylic dielectric elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Junjie; Chen, Hualing; Li, Bo; Chang, Longfei [Xi' an Jiaotong University, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an (China); Xi' an Jiaotong University, School of Mechanical Engineering, Xi' an (China)

    2013-02-15

    The dielectric constant is an essential electrical parameter to the achievable voltage-induced deformation of the dielectric elastomer. This paper primarily focuses on the temperature dependence of the dielectric constant (within the range of 173 K to 373 K) for the most widely used acrylic dielectric elastomer (VHB 4910). First the dielectric constant was investigated experimentally with the broadband dielectric spectrometer (BDS). Results showed that the dielectric constant first increased with temperature up to a peak value and then dropped to a relative small value. Then by analyzing the fitted curves, the Cole-Cole dispersion equation was found better to characterize the rising process before the peak values than the Debye dispersion equation, while the decrease process afterward can be well described by the simple Debye model. Finally, a mathematical model of dielectric constant of VHB 4910 was obtained from the fitted results which can be used to further probe the electromechanical stability of the dielectric elastomers. (orig.)

  12. Ca2+- and Mg2+-ATPase activities in winter wheat root plasma membranes as affected by NaCl stress during growth

    NARCIS (Netherlands)

    Mansour, MMF; van Hasselt, PR; Kuiper, PJC

    1998-01-01

    Winter wheat seedlings were grown in Hoagland nutrient solution with or without 100 mmol/L NaCl added. Plasma membranes from root cells were prepared by aqueous polymer two phase partitioning and the stimulation of plasma membrane ATPase activity by Mg2+ and Ca2+ was investigated. The enzyme was act

  13. Anisotropic dielectric substrate as thin dielectric resonator

    Czech Academy of Sciences Publication Activity Database

    Bovtun, Viktor; Pashkov, V.; Kempa, Martin; Molchanov, V.; Kamba, Stanislav; Poplavko, Y.; Yakymenko, Y.

    Sevastopol: Weber Publishing, 2012 - (Yermolov, P.), s. 573-574 ISBN 978-966-335-370-8. [International Conference Microwave & Telecommunication Technology /22./. Sevastopol (UA), 10.09.2012-14.09.2012] R&D Projects: GA ČR GAP204/12/1163 Institutional research plan: CEZ:AV0Z10100520 Keywords : dielectric resonator * substrate * microwave Subject RIV: BM - Solid Matter Physics ; Magnetism http://www.crimico.org/en/

  14. Graphene-on-dielectric micromembrane for optoelectromechanical hybrid devices

    DEFF Research Database (Denmark)

    Schmid, Silvan; Bagci, Tolga; Zeuthen, Emil;

    2013-01-01

    Due to their exceptional mechanical and optical properties, dielectric silicon nitride (SiN) micromembranes have become the centerpiece of many optomechanical experiments. Efficient capacitive coupling of the membrane to an electrical system would facilitate exciting hybrid optoelectromechanical...... devices. However, capacitive coupling of such SiN membranes is rather weak. Here we add a single layer of graphene on SiN micromembranes (SiN-G) and compare the electromechanical coupling and mechanical properties to bare SiN membranes and to membranes coated with an aluminium layer (SiN-Al). The...... electrostatic force to external coplanar electrodes of SiN-G membranes is found to be equal to that of the SiN-Al membranes and corresponds to the theoretical value calculated for a perfectly conductive membrane coating. Our results show that a single layer of graphene substantially enhances the...

  15. A dielectric resonator method of measuring dielectric properties of low loss materials in the microwave region

    Science.gov (United States)

    Sheen, Jyh

    2008-05-01

    A technique for the measurement of dielectric properties of low loss and homogeneously isotropic media in the microwave region is studied. The measuring structure is a resonator made up of a cylindrical dielectric rod and conducting plates. The dielectric constants and loss tangents are computed from the resonant frequencies, structure dimensions and unloaded Qs of the TE01δ mode. A simple field model is introduced to analyze this resonator structure. Unlike other simple models, this model does not have the defect of low measurement accuracy of dielectric properties. Important factors affecting the dielectric properties measurements are introduced. Error sources for measurements are also discussed. The measurement accuracy is justified by comparing the results with those of other techniques. In addition, various methods for calculating the power factor and conducting loss and for measuring the conductivity of the conducting plates are discussed. The accuracies of certain of these methods have not previously been studied, but are given in this paper. The swept frequency capability was also studied. It was found that dielectric properties in microwave frequencies could be measured within a frequency range of 3 GHz.

  16. A dielectric resonator method of measuring dielectric properties of low loss materials in the microwave region

    International Nuclear Information System (INIS)

    A technique for the measurement of dielectric properties of low loss and homogeneously isotropic media in the microwave region is studied. The measuring structure is a resonator made up of a cylindrical dielectric rod and conducting plates. The dielectric constants and loss tangents are computed from the resonant frequencies, structure dimensions and unloaded Qs of the TE01δ mode. A simple field model is introduced to analyze this resonator structure. Unlike other simple models, this model does not have the defect of low measurement accuracy of dielectric properties. Important factors affecting the dielectric properties measurements are introduced. Error sources for measurements are also discussed. The measurement accuracy is justified by comparing the results with those of other techniques. In addition, various methods for calculating the power factor and conducting loss and for measuring the conductivity of the conducting plates are discussed. The accuracies of certain of these methods have not previously been studied, but are given in this paper. The swept frequency capability was also studied. It was found that dielectric properties in microwave frequencies could be measured within a frequency range of 3 GHz

  17. Cell Electrofusion in Centrifuged Erythrocyte Pellets Assessed by Dielectric Spectroscopy.

    Science.gov (United States)

    Asami, Koji

    2016-04-01

    We have characterized cell electrofusion in cell pellets by dielectric spectroscopy. Cell pellets were formed from horse erythrocyte suspensions by centrifugation and were subjected to intense AC pulses. The dielectric spectra of the pellets were measured over a frequency range of 10 Hz to 10 MHz. The application of AC pulses caused low-frequency (LF) dielectric relaxation below about 100 kHz. The LF dielectric relaxation was markedly affected not only by pretreatment of cells at 50 °C, which disrupts the spectrin network of erythrocytes, but also by the parameters of the AC pulses (frequency of the sine wave and repeat count of the pulses). The occurrence of the LF dielectric relaxation was qualitatively accounted for by modeling fusion products in the pellet by prolate spheroidal cells whose long axes run parallel to the applied electric field. PMID:26407874

  18. Dielectric Constant of Suspensions

    Science.gov (United States)

    Mendelson, Kenneth S.; Ackmann, James J.

    1997-03-01

    We have used a finite element method to calculate the dielectric constant of a cubic array of spheres. Extensive calculations support preliminary conclusions reported previously (K. Mendelson and J. Ackmann, Bull. Am. Phys. Soc. 41), 657 (1996).. At frequencies below 100 kHz the real part of the dielectric constant (ɛ') shows oscillations as a function of the volume fraction of suspension. These oscillations disappear at low conductivities of the suspending fluid. Measurements of the dielectric constant (J. Ackmann, et al., Ann. Biomed. Eng. 24), 58 (1996). (H. Fricke and H. Curtis, J. Phys. Chem. 41), 729 (1937). are not sufficiently sensitive to show oscillations but appear to be consistent with the theoretical results.

  19. PREFACE: Dielectrics 2013

    Science.gov (United States)

    Hadjiloucas, Sillas; Blackburn, John

    2013-11-01

    This volume records the 42nd Dielectrics Group Proceedings of the Dielectrics Conference that took place at the University of Reading UK from 10-12 April 2013. The meeting is part of the biennial Dielectrics series of the Dielectrics Group, and formerly Dielectrics Society, and is organised by the Institute of Physics. The conference proceedings showcase some of the diversity and activity of the Dielectrics community worldwide, and bring together contributions from academics and industrial researchers with a diverse background and experiences from the Physics, Chemistry and Engineering communities. It is interesting to note some continuing themes such as Insulation/HV Materials, Dielectric Spectroscopy, Dielectric Measurement Techniques and Ferroelectric materials have a growing importance across a range of technologically important areas from the Energy sector to Materials research, Semiconductor and Electronics industries, and Metrology. We would like to thank all of our colleagues and friends in the Dielectrics community who have supported this event by contributing manuscripts and participating in the event. The conference has provided excellent networking opportunities for all delegates. Our thanks go also to our theme chairs: Dr Stephen Dodd (University of Leicester) on Insulation/HV Materials, Professor Darryl Almond (University of Bath) on Dielectric Spectroscopy, Dr John Blackburn (NPL) on Dielectric Measurement Techniques and Professor Anthony R West (University of Sheffield) on Ferroelectric Materials. We would also like to thank the other members of the Technical Programme Committee for their support, and refereeing the submitted manuscripts. Our community would also like to wish a full recovery to our plenary speaker Prof John Fothergill (City University London) who was unexpectedly unable to give his talk as well as thank Professor Alun Vaughan for stepping in and giving an excellent plenary lecture in his place at such very short notice. We are also

  20. Development of dielectric microcalorimeter

    International Nuclear Information System (INIS)

    A prototype dielectric microcalorimeter was fabricated from 0.99SrTiO3-0.01SrTa2O6, a dielectric material. To estimate the operation performance of the microcalorimeter, a simple evaluation model is introduced by employing the block diagram formalism. Pulse height and fall time constant of the detection signal are analyzed as a function of the thermal conductance of the heat link. The dielectric microcalorimeter maintained at 100 mK was irradiated by 5.5 MeV α-particles emitting from an 241Am source. Responsivity was found to be 2.7x10-19 C/eV. (author)

  1. Polymer Composite and Nanocomposite Dielectric Materials for Pulse Power Energy Storage

    Directory of Open Access Journals (Sweden)

    Hans-Conrad zur Loye

    2009-10-01

    Full Text Available This review summarizes the current state of polymer composites used as dielectric materials for energy storage. The particular focus is on materials: polymers serving as the matrix, inorganic fillers used to increase the effective dielectric constant, and various recent investigations of functionalization of metal oxide fillers to improve compatibility with polymers. We review the recent literature focused on the dielectric characterization of composites, specifically the measurement of dielectric permittivity and breakdown field strength. Special attention is given to the analysis of the energy density of polymer composite materials and how the functionalization of the inorganic filler affects the energy density of polymer composite dielectric materials.

  2. Prolonged extracorporeal membrane oxygenation therapy for severe acute respiratory distress syndrome in a child affected by rituximab-resistant autoimmune hemolytic anemia: a case report

    Directory of Open Access Journals (Sweden)

    Beretta Chiara

    2009-04-01

    Full Text Available Abstract Introduction Autoimmune hemolytic anemia in children younger than 2 years of age is usually characterized by a severe course, with a mortality rate of approximately 10%. The prolonged immunosuppression following specific treatment may be associated with a high risk of developing severe infections. Recently, the use of monoclonal antibodies (rituximab has allowed sustained remissions to be obtained in the majority of pediatric patients with refractory autoimmune hemolytic anemia. Case presentation We describe the case of an 8-month-old Caucasian girl affected by a severe form of autoimmune hemolytic anemia, which required continuous steroid treatment for 16 months. Thereafter, she received 4 weekly doses of rituximab (375 mg/m2/dose associated with steroid therapy, which was then tapered over the subsequent 2 weeks. One month after the last dose of rrituximab, she presented with recurrence of severe hemolysis and received two more doses of rrituximab. The patient remained in clinical remission for 7 months, before presenting with a further relapse. An alternative heavy immunosuppressive therapy was administered combining cyclophosphamide 10 mg/kg/day for 10 days with methylprednisolone 40 mg/kg/day for 5 days, which was then tapered down over 3 weeks. While still on steroid therapy, the patient developed an interstitial pneumonia with Acute Respiratory Distress Syndrome, which required immediate admission to the intensive care unit where extracorporeal membrane oxygenation therapy was administered continuously for 37 days. At 16-month follow-up, the patient is alive and in good clinical condition, with no organ dysfunction, free from any immunosuppressive treatment and with a normal Hb level. Conclusions This case shows that aggressive combined immunosuppressive therapy may lead to a sustained complete remission in children with refractory autoimmune hemolytic anemia. However, the severe life-threatening complication presented by our

  3. Dielectric behaviour of polycarbonate

    Science.gov (United States)

    El-Shabasy, M.; Riad, A. S.

    1996-05-01

    The dielectric constant and the dielectric loss of polycarbonate are investigated in the frequency range 30-10 5 Hz and at temperature from 297 to 365 K. The frequency dependence of the impedance spectra plotted in the complex plane shows semicircles. The system could be represented by an equivalent circuit of a bulk resistance in series with a parallel surface resistance-capacitance combination. The Cole-Cole diagrams have been used to determine the molecular relaxation time τ. The temperature dependence of τ is expressed by a thermally activated process. Analysis of the AC conductivity reveals semiconducting features based predominantly on a hopping mechanism.

  4. Multilayer dielectric diffraction gratings

    Science.gov (United States)

    Perry, Michael D.; Britten, Jerald A.; Nguyen, Hoang T.; Boyd, Robert; Shore, Bruce W.

    1999-01-01

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

  5. Dielectric analysis of halloysite nanotubes LLDPE nanocomposite compounds

    Science.gov (United States)

    Čermák, M.; Kadlec, P.; Kruliš, Z.; Polanský, R.

    2016-03-01

    The aim of this paper is to investigate the influence of HNT on the dielectric properties of LLDPE (linear low density polyethylene) nanocomposite compounds in the different level of fulfillment (0, 1, 3, 7 wt%). The utilization of these HNT/LLDPE nanocomposite compounds can be seen in the cable industry, where the dielectric properties are essential. Used experimental compounds have been prepared in the laboratory blades mixer Brabender W50 EHT and the plasticorder Brabender PLE 651. Immediately after mixing, the molten compounds were removed from the mixer, inserted into the spacer, and pressed into films of 0.25 mm thickness. Dielectric properties in the DC field (polarization current, reading of polarization index, volume resistivity) of the individual samples were measured and the temperature and frequency range by Broadband dielectric spectroscopy Alpha-A (Novocontrol) were investigated. Samples have been subjected to the dielectric strength test according to standards. As results showed, experimental samples were affected by HNT, especially in the dielectric relaxation phenomena, when during the increment of the level of fulfilment occurred the increasing of the nearly lossless dielectric relaxations. The volume resistivity of the samples was affected in the range of one magnitude.

  6. Dyes with high dielectric constants

    OpenAIRE

    Langhals, Heinz

    1988-01-01

    The dielectric constants of perylene dyes, perylene-3,4: 9,10-tetracarboxylic bisimides, are reported. With aromatic substituents, dielectric constants up to 110 are obtained. With polymeric dyes, the dielectric constants rise to 260. Mechanisms and applications are discussed.

  7. Fabrication Process of Silicone-based Dielectric Elastomer Actuators.

    Science.gov (United States)

    Rosset, Samuel; Araromi, Oluwaseun A; Schlatter, Samuel; Shea, Herbert R

    2016-01-01

    This contribution demonstrates the fabrication process of dielectric elastomer transducers (DETs). DETs are stretchable capacitors consisting of an elastomeric dielectric membrane sandwiched between two compliant electrodes. The large actuation strains of these transducers when used as actuators (over 300% area strain) and their soft and compliant nature has been exploited for a wide range of applications, including electrically tunable optics, haptic feedback devices, wave-energy harvesting, deformable cell-culture devices, compliant grippers, and propulsion of a bio-inspired fish-like airship. In most cases, DETs are made with a commercial proprietary acrylic elastomer and with hand-applied electrodes of carbon powder or carbon grease. This combination leads to non-reproducible and slow actuators exhibiting viscoelastic creep and a short lifetime. We present here a complete process flow for the reproducible fabrication of DETs based on thin elastomeric silicone films, including casting of thin silicone membranes, membrane release and prestretching, patterning of robust compliant electrodes, assembly and testing. The membranes are cast on flexible polyethylene terephthalate (PET) substrates coated with a water-soluble sacrificial layer for ease of release. The electrodes consist of carbon black particles dispersed into a silicone matrix and patterned using a stamping technique, which leads to precisely-defined compliant electrodes that present a high adhesion to the dielectric membrane on which they are applied. PMID:26863283

  8. Depletion of acyl-coenzyme A-binding protein affects sphingolipid synthesis and causes vesicle accumulation and membrane defects in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Gaigg, B; Neergaard, T B; Schneiter, R; Hansen, J.K.; Faergeman, N J; Jensen, N A; Andersen, J R; Friis, J; Sandhoff, R; Schrøder, H D; Knudsen, J

    2001-01-01

    -70%. The reduced incorporation of [(3)H]myo-inositol into sphingolipids was due to a reduced incorporation into inositol-phosphoceramide and mannose-inositol-phosphoceramide only, a pattern that is characteristic for cells with aberrant endoplasmic reticulum to Golgi transport. The plasma membrane of the...... Acb1p-depleted strain contained increased levels of inositol-phosphoceramide and mannose-inositol-phosphoceramide and lysophospholipids. Acb1p-depleted cells accumulated 50- to 60-nm vesicles and autophagocytotic like bodies and showed strongly perturbed plasma membrane structures. The present results...

  9. The evolutionarily conserved protein PHOTOSYNTHESIS AFFECTED MUTANT71 is required for efficient manganese uptake at the thylakoid membrane in Arabidopsis

    DEFF Research Database (Denmark)

    Schneider, Anja; Steinberger, Iris; Herdean, Andrei;

    2016-01-01

    thylakoids relative to the wild type. The changes in Ca2+ homeostasis were accompanied by an increased contribution of the transmembrane electrical potential to the proton motive force across the thylakoid membrane. PSII activity in pam71 plants and the corresponding Chlamydomonas reinhardtii mutant cgld1...

  10. Solvent determined conformation of gramicidin affects the ability of the peptide to induce hexagonal HH phase formation in dioleoylphosphatidylcholine model membranes

    NARCIS (Netherlands)

    Tournois, H.; Killian, J.A.; Urry, D.W.; Bokking, O.R.; Gier, J. de; Kruijff, B. de

    1987-01-01

    It is shown by 31P-NMR and small angle X-ray scattering that induction of an hexagonal HH phase in dioleoylphosphatidylcholine model membranes by external addition of gramicidin A′ depends on the solvent which is used to solubilize the peptide. Addition of gramicidin from dimethylsulfoxide or triflu

  11. Disruption of the lipid-transporting LdMT-LdRos3 complex in Leishmania donovani affects membrane lipid asymmetry but not host cell invasion.

    Directory of Open Access Journals (Sweden)

    Adrien Weingärtner

    Full Text Available Maintenance and regulation of the asymmetric lipid distribution across eukaryotic plasma membranes is governed by the concerted action of specific membrane proteins controlling lipid movement across the bilayer. Here, we show that the miltefosine transporter (LdMT, a member of the P4-ATPase subfamily in Leishmania donovani, and the Cdc50-like protein LdRos3 form a stable complex that plays an essential role in maintaining phospholipid asymmetry in the parasite plasma membrane. Loss of either LdMT or LdRos3 abolishes ATP-dependent transport of NBD-labelled phosphatidylethanolamine (PE and phosphatidylcholine from the outer to the inner plasma membrane leaflet and results in an increased cell surface exposure of endogenous PE. We also find that promastigotes of L. donovani lack any detectable amount of phosphatidylserine (PS but retain their infectivity in THP-1-derived macrophages. Likewise, infectivity was unchanged for parasites without LdMT-LdRos3 complexes. We conclude that exposure of PS and PE to the exoplasmic leaflet is not crucial for the infectivity of L. donovani promastigotes.

  12. Disruption of the lipid-transporting LdMT-LdRos3 complex in Leishmania donovani affects membrane lipid asymmetry but not host cell invasion.

    Science.gov (United States)

    Weingärtner, Adrien; Drobot, Björn; Herrmann, Andreas; Sánchez-Cañete, María P; Gamarro, Francisco; Castanys, Santiago; Günther Pomorski, Thomas

    2010-01-01

    Maintenance and regulation of the asymmetric lipid distribution across eukaryotic plasma membranes is governed by the concerted action of specific membrane proteins controlling lipid movement across the bilayer. Here, we show that the miltefosine transporter (LdMT), a member of the P4-ATPase subfamily in Leishmania donovani, and the Cdc50-like protein LdRos3 form a stable complex that plays an essential role in maintaining phospholipid asymmetry in the parasite plasma membrane. Loss of either LdMT or LdRos3 abolishes ATP-dependent transport of NBD-labelled phosphatidylethanolamine (PE) and phosphatidylcholine from the outer to the inner plasma membrane leaflet and results in an increased cell surface exposure of endogenous PE. We also find that promastigotes of L. donovani lack any detectable amount of phosphatidylserine (PS) but retain their infectivity in THP-1-derived macrophages. Likewise, infectivity was unchanged for parasites without LdMT-LdRos3 complexes. We conclude that exposure of PS and PE to the exoplasmic leaflet is not crucial for the infectivity of L. donovani promastigotes. PMID:20865154

  13. Model and design of dielectric elastomer minimum energy structures

    International Nuclear Information System (INIS)

    Fixing a prestretched dielectric elastomer actuator (DEA) on a flexible frame allows transformation of the intrinsic in-plane area expansion of DEAs into complex three-dimensional (3D) structures whose shape is determined by a configuration that minimizes the elastic energy of the actuator and the bending energy of the frame. These stuctures can then unfold upon the application of a voltage. This article presents an analytical modelling of the dielectric elastomer minimal energy structure in the case of a simple rectangular geometry and studies the influence of the main design parameters on the actuator's behaviour. The initial shape of DEMES, as well as the actuation range, depends on the elastic strain energy stored in the elastomeric membrane. This energy depends on two independent parameters: the volume of the membrane and its initial deformation. There exist therefore different combinations of membrane volume and prestretch, which lead to the same initial shape, such as a highly prestretched thin membrane, or a slightly prestretched thick membrane. Although they have the same initial shape, these different membrane states lead to different behaviour once the actuation voltage is applied. Our model allows one to predict which choice of parameters leads to the largest actuation range, while specifying the impact of the different membrane conditions on the spring constant of the device. We also explore the effects of non-ideal material behaviour, such as stress relaxation, on device performance. (paper)

  14. Dielectric Signatures of Annealing in Glacier Ice

    Science.gov (United States)

    Grimm, R. E.; Stillman, D. E.; MacGregor, J. A.

    2015-12-01

    We analyzed the dielectric spectra of 49 firn and ice samples from ice sheets and glaciers to better understand how differing ice formation and evolution affect electrical properties. The dielectric relaxation of ice is well known and its characteristic frequency increases with the concentration of soluble impurities in the ice lattice. We found that meteoric ice and firn generally possess two such relaxations, indicating distinct crystal populations or zonation. Typically, one population is consistent with that of relatively pure ice, and the other is significantly more impure. However, high temperatures (e.g., temperate ice), long residence times (e.g., ancient ice from Mullins Glacier, Antarctica), or anomalously high impurity concentrations favor the development of a single relaxation. These relationships suggest that annealing causes two dielectrically distinct populations to merge into one population. The dielectric response of temperate ice samples indicates increasing purity with increasing depth, suggesting final rejection of impurities from the lattice. Separately, subglacially frozen samples from the Vostok 5G ice core possess a single relaxation whose variable characteristic frequency likely reflects the composition of the source water. Multi-frequency electrical measurements on cores and in the field can track annealing of glacier ice.

  15. Factors affecting the formation of zeolite seed layers and the effects of seed layers on the growth of zeolite silicalite-1 membranes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiongfu; LIU Hai'ou; WANG Anjie; WANG Jinqu

    2007-01-01

    The present study investigates the formation of silicalite-1 seed layers on a porous carbon support of 0.5 μm pore size and a-Al2O3 supports with different pore sizes (0.1 μm and 4 μm) via the slip-casting technique.The effects of support property,seed size and solvent on the formation of seed layers were investigated in detail.The growth of silicalite-1 membranes on different seeded supports by hydrothermal synthesis was also evaluated.The scanning electron microscopy (SEM) and X-ray diffraction (XRD) characterizations indicate that a continuous seed layer can be obtained on the smooth support of 0.1 μm pore size by using any seed of 100 nm,600 nm or 2.2 μm in size,whereas,on the coarse supports with either 0.5 μm or 4 μm pore size,a continuous seed layer cannot be formed using the above seed sizes and the same seeding time.At a longer contact time,a seed layer can also be formed using 100 nm seed on the supports with larger pore size.However,the layer is not uniform and smooth.For a hydrophobic porous carbon support,seeding ethanol suspension,which has weak polarity,favors the formation of a continuous seed layer.The seed layers and membranes grown from the smaller seed are more uniform and continuous and possess smoother surfaces than those from the larger seed.The seed layer and respective grown membrane formed from nanosized seed (100 nm) are the most uniform and compact.With this method of seeded secondary synthesis of zeolite membranes,the quality of a membrane mainly 、depends on the quality of the seed layer.

  16. Measuring the dielectric properties of soil-organic mixtures using coaxial impedance dielectric reflectometry

    Science.gov (United States)

    Francisca, Franco M.; Montoro, Marcos A.

    2012-05-01

    Contamination of soils with non-aqueous phase liquids (NAPLs) is frequently produced by accidental spills and storage tanks or pipes leakage. The main goals dealing with soil and groundwater contamination include determining the extension of the affected zone, monitoring the contaminant plume and quantifying the pollution degree. The objective of this work is to evaluate the potential of dielectric permittivity measurements to detect the presence of NAPLs in sands. Tested samples were fine, medium, coarse and silty sand with different volumetric contents of water and paraffin oil. The dielectric permittivity was measured by means of a Coaxial Impedance Dielectric Reflectometry method in specimens with either known fluid content or at different stages during immiscible displacement tests. A simplified method was developed to quantify the amount of oil from dielectric permittivity measurements and effective mixture media models. Obtained results showed that groundwater contamination with NAPL and the monitoring of immiscible fluid displacement in saturated porous media can be clearly identified from dielectric measurements. Finally, very accurate results can be obtained when computing the contamination degree with the proposed method in comparison with the real volumetric content of NAPL (r2 > 90%).

  17. Antenna with Dielectric Having Geometric Patterns

    Science.gov (United States)

    Dudley, Kenneth L. (Inventor); Elliott, Holly A. (Inventor); Cravey, Robin L. (Inventor); Connell, John W. (Inventor); Ghose, Sayata (Inventor); Watson, Kent A. (Inventor); Smith, Jr., Joseph G. (Inventor)

    2013-01-01

    An antenna includes a ground plane, a dielectric disposed on the ground plane, and an electrically-conductive radiator disposed on the dielectric. The dielectric includes at least one layer of a first dielectric material and a second dielectric material that collectively define a dielectric geometric pattern, which may comprise a fractal geometry. The radiator defines a radiator geometric pattern, and the dielectric geometric pattern is geometrically identical, or substantially geometrically identical, to the radiator geometric pattern.

  18. Polyarylether composition and membrane

    Science.gov (United States)

    Hung, Joyce; Brunelle, Daniel Joseph; Harmon, Marianne Elisabeth; Moore, David Roger; Stone, Joshua James; Zhou, Hongyi; Suriano, Joseph Anthony

    2010-11-09

    A composition including a polyarylether copolymer is provided. The copolymer includes a polyarylether backbone; and a sulfonated oligomeric group bonded to the polyarylether suitable for use as a cation conducting membrane. Method of bonding a sulfonated oligomeric group to the polyarylether backbone to form a polyarylether copolymer. The membrane may be formed from the polyarylether copolymer composition. The chain length of the sulfonated oligomeric group may be controlled to affect or control the ion conductivity of the membrane.

  19. How the Dimension of Space Affects the Products of Pre-Biotic Evolution: The Spatial Population Dynamics of Structural Complexity and The Emergence of Membranes

    OpenAIRE

    Piantadosi, Steve T.; Crutchfield, James P.

    2010-01-01

    We show that autocatalytic networks of epsilon-machines and their population dynamics differ substantially between spatial (geographically distributed) and nonspatial (panmixia) populations. Generally, regions of spacetime-invariant autocatalytic networks---or domains---emerge in geographically distributed populations. These are separated by functional membranes of complementary epsilon-machines that actively translate between the domains and are responsible for their growth and stability. We...

  20. Solvent determined conformation of gramicidin affects the ability of the peptide to induce hexagonal HH phase formation in dioleoylphosphatidylcholine model membranes

    OpenAIRE

    Tournois, H.; Killian, J A; Urry, D W; Bokking, O.R.; de Gier, J.; Kruijff, B. de

    1987-01-01

    It is shown by 31P-NMR and small angle X-ray scattering that induction of an hexagonal HH phase in dioleoylphosphatidylcholine model membranes by external addition of gramicidin A′ depends on the solvent which is used to solubilize the peptide. Addition of gramicidin from dimethylsulfoxide or trifluoroethanol solution leads to HH phase formation whereas addition of the peptide from ethanol does not. This solvent dependence is shown by circular dichroism to be correlated with the peptide confo...

  1. All-dielectric metamaterials

    Science.gov (United States)

    Jahani, Saman; Jacob, Zubin

    2016-01-01

    The ideal material for nanophotonic applications will have a large refractive index at optical frequencies, respond to both the electric and magnetic fields of light, support large optical chirality and anisotropy, confine and guide light at the nanoscale, and be able to modify the phase and amplitude of incoming radiation in a fraction of a wavelength. Artificial electromagnetic media, or metamaterials, based on metallic or polar dielectric nanostructures can provide many of these properties by coupling light to free electrons (plasmons) or phonons (phonon polaritons), respectively, but at the inevitable cost of significant energy dissipation and reduced device efficiency. Recently, however, there has been a shift in the approach to nanophotonics. Low-loss electromagnetic responses covering all four quadrants of possible permittivities and permeabilities have been achieved using completely transparent and high-refractive-index dielectric building blocks. Moreover, an emerging class of all-dielectric metamaterials consisting of anisotropic crystals has been shown to support large refractive index contrast between orthogonal polarizations of light. These advances have revived the exciting prospect of integrating exotic electromagnetic effects in practical photonic devices, to achieve, for example, ultrathin and efficient optical elements, and realize the long-standing goal of subdiffraction confinement and guiding of light without metals. In this Review, we present a broad outline of the whole range of electromagnetic effects observed using all-dielectric metamaterials: high-refractive-index nanoresonators, metasurfaces, zero-index metamaterials and anisotropic metamaterials. Finally, we discuss current challenges and future goals for the field at the intersection with quantum, thermal and silicon photonics, as well as biomimetic metasurfaces.

  2. Dielectric Wakefield Researches

    International Nuclear Information System (INIS)

    Excitation of wakefield in cylindrical dielectric waveguide/resonator by a sequence of relativistic electron bunches was investigated using an electron linac 'Almaz-2' (4.5 MeV, 6·103 bunches of duration 60 ps and charge 0.32 nC each). Energy spectrum of electrons, radial topography and longitudinal distribution of wakefield, and total energy of excited wakefield were measured by means of magnetic analyzer, high frequency probe, and a sensitive calorimeter

  3. All-dielectric metamaterials.

    Science.gov (United States)

    Jahani, Saman; Jacob, Zubin

    2016-01-01

    The ideal material for nanophotonic applications will have a large refractive index at optical frequencies, respond to both the electric and magnetic fields of light, support large optical chirality and anisotropy, confine and guide light at the nanoscale, and be able to modify the phase and amplitude of incoming radiation in a fraction of a wavelength. Artificial electromagnetic media, or metamaterials, based on metallic or polar dielectric nanostructures can provide many of these properties by coupling light to free electrons (plasmons) or phonons (phonon polaritons), respectively, but at the inevitable cost of significant energy dissipation and reduced device efficiency. Recently, however, there has been a shift in the approach to nanophotonics. Low-loss electromagnetic responses covering all four quadrants of possible permittivities and permeabilities have been achieved using completely transparent and high-refractive-index dielectric building blocks. Moreover, an emerging class of all-dielectric metamaterials consisting of anisotropic crystals has been shown to support large refractive index contrast between orthogonal polarizations of light. These advances have revived the exciting prospect of integrating exotic electromagnetic effects in practical photonic devices, to achieve, for example, ultrathin and efficient optical elements, and realize the long-standing goal of subdiffraction confinement and guiding of light without metals. In this Review, we present a broad outline of the whole range of electromagnetic effects observed using all-dielectric metamaterials: high-refractive-index nanoresonators, metasurfaces, zero-index metamaterials and anisotropic metamaterials. Finally, we discuss current challenges and future goals for the field at the intersection with quantum, thermal and silicon photonics, as well as biomimetic metasurfaces. PMID:26740041

  4. Dielectric lattice gauge theory

    International Nuclear Information System (INIS)

    Dielectric lattice gauge theory models are introduced. They involve variables PHI(b)epsilong that are attached to the links b = (x+esub(μ),x) of the lattice and take their values in the linear space g which consists of real linear combinations of matrices in the gauge group G. The polar decomposition PHI(b)=U(b)osub(μ)(x) specifies an ordinary lattice gauge field U(b) and a kind of dielectric field epsilonsub(ij)proportionalosub(i)osub(j)sup(*)deltasub(ij). A gauge invariant positive semidefinite kinetic term for the PHI-field is found, and it is shown how to incorporate Wilson fermions in a way which preserves Osterwalder Schrader positivity. Theories with G = SU(2) and without matter fields are studied in some detail. It is proved that confinement holds, in the sense that Wilson loop expectation values show an area law decay, if the Euclidean action has certain qualitative features which imply that PHI = 0 (i.e. dielectric field identical 0) is the unique maximum of the action. (orig.)

  5. Continuum Electromechanical Modeling of Protein-Membrane Interaction

    OpenAIRE

    Y. C. ZHOU; Lu, Benzhuo; Gorfe, Alemayehu A.

    2010-01-01

    A continuum electromechanical model is proposed to describe the membrane curvature induced by electrostatic interactions in a solvated protein-membrane system. The model couples the macroscopic strain energy of membrane and the electrostatic solvation energy of the system, and equilibrium membrane deformation is obtained by minimizing the electro-elastic energy functional with respect to the dielectric interface. The model is illustrated with the systems with increasing geometry complexity an...

  6. Additive manufacturing of graded dielectrics

    International Nuclear Information System (INIS)

    A method for the fabrication of graded dielectrics within a structural composite is presented. This system employs an ultrasonic powder deposition head to print high dielectric powders onto a woven fabric composite substrate. It is shown how this system can integrate 3D variations of dielectric properties at millimeter resolution within a mechanically rugged substrate. To conclude, the system’s practical application is demonstrated with experimental results from a graded index lens. (paper)

  7. Genetic study of a membrane protein: DNA sequence alterations due to 17 lamB point mutations affecting adsorption of phage lambda.

    OpenAIRE

    Clément, J M; Lepouce, E; Marchal, C.; Hofnung, M

    1983-01-01

    Gene lamB encodes the outer membrane receptor for phage lambda in Escherichia coli K12. We have determined the DNA sequence alterations of 17 lamB point mutations which result in resistance to phage lambda h+. The mutations correspond to four phenotypic classes according to the pattern of growth of three phages which use the lambda receptor: lambda h (a one-step host-range derivative of lambda h+), lambda hh* (a two-step host-range derivative of lambda h+) and K10 (another lambdoid phage). Fo...

  8. Dielectric properties of fly ash

    Indian Academy of Sciences (India)

    S C Raghavendra; R L Raibagkar; A B Kulkarni

    2002-02-01

    This paper reports the dielectric properties of fly ash. The dielectric measurements were performed as a function of frequency and temperature. The sample of fly ash shows almost similar behaviour in the frequency and temperature range studied. The large value of dielectric constant in the typical frequency range is because of orientation polarization and tight binding force between the ions or atoms in the fly ash. The sample of fly ash is of great scientific and technological interest because of its high value of dielectric constant (104).

  9. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications for...

  10. Changes in ganglioside content affect the binding of Clostridium perfringens epsilon-toxin to detergent-resistant membranes of Madin-Darby canine kidney cells.

    Science.gov (United States)

    Shimamoto, Seiko; Tamai, Eiji; Matsushita, Osamu; Minami, Junzaburo; Okabe, Akinobu; Miyata, Shigeru

    2005-01-01

    Epsilon-toxin (ET) of Clostridium perfringens, which causes fatal enterotoxemia in ungulates, was previously shown to bind to and form a heptameric pore within the detergent-resistant membranes (DRMs) of MDCK cells. Depletion of cholesterol has also been shown to decrease the cytotoxicity of ET and its heptamerization. In this study, we investigated the effects of changes in sphingolipids, other DRM components of MDCK cells, on the cells' susceptibility to ET. Treatment with fumonisin B1 and PDMP, inhibitors of sphingolipid and glycosphingolipid syntheses, respectively, increased the susceptibility, while D609, a sphingomyelin synthesis inhibitor, had the opposite effect. The exogenous addition of ganglioside G(M1) dramatically decreased the ET binding, heptamerization and cytotoxicity. These effects were shown not to be due to ET binding to G(M1) or to denaturation of ET. We also found that the ET cytotoxicity towards MDCK cells decreased with an increase in culture time. In accordance with the resistance observed for prolonged cultured cells, G(M3), a major ganglioside component, increased and sialidase treatment increased their susceptibility. These results suggest that membrane-anchored sialic acid of G(M3) within DRMs inhibits ET binding, leading to prevention of the heptamerization of ET and cell death. It is also suggested that sialidase produced by this organism aids the targeting of ET to MDCK cells. PMID:15781998

  11. Flux recovery of ceramic tubular membranes fouled with whey proteins: Some aspects of membrane cleaning

    OpenAIRE

    Popović Svetlana S.; Milanović Spasenija D.; Iličić Mirela D.; Lukić Nataša Lj.; Šijački Ivana M.

    2008-01-01

    Efficiency of membrane processes is greatly affected by the flux reduction due to the deposits formation at the surface and/or in the pores of the membrane. Efficiency of membrane processes is affected by cleaning procedure applied to regenerate flux. In this work, flux recovery of ceramic tubular membranes with 50 and 200 nm pore size was investigated. The membranes were fouled with reconstituted whey solution for 1 hour. After that, the membranes were rinsed with clean water and then cleane...

  12. Kelvin probe study of laterally inhomogeneous dielectric charging and charge diffusion in RF MEMS capacitive switches

    OpenAIRE

    Herfst, R.W.; Steeneken, P. G.; Schmitz, J; Mank, A.J.G.; Gils, van, S.H.

    2008-01-01

    In this paper we use scanning Kelvin probe microscopy (SKPM) to detect charge in the dielectric of RF MEMS capacitive switches. We observe a laterally inhomogeneous distribution. Laterally inhomogeneous dielectric charging leads to a narrowing of the C-V curve [1], and can lead to stiction of the membrane. The measurements show that trapped charges slowly diffuse, which reduces the inhomogeneity and shows that charge is vertically confined. From these measurements we estimate the lateral diff...

  13. Ionic structure in liquids confined by dielectric interfaces

    Science.gov (United States)

    Jing, Yufei; Jadhao, Vikram; Zwanikken, Jos W.; Olvera de la Cruz, Monica

    2015-11-01

    The behavior of ions in liquids confined between macromolecules determines the outcome of many nanoscale assembly processes in synthetic and biological materials such as colloidal dispersions, emulsions, hydrogels, DNA, cell membranes, and proteins. Theoretically, the macromolecule-liquid boundary is often modeled as a dielectric interface and an important quantity of interest is the ionic structure in a liquid confined between two such interfaces. The knowledge gleaned from the study of ionic structure in such models can be useful in several industrial applications, such as in the design of double-layer supercapacitors for energy storage and in the extraction of metal ions from wastewater. In this article, we compute the ionic structure in a model system of electrolyte confined by two planar dielectric interfaces using molecular dynamics simulations and liquid state theory. We explore the effects of high electrolyte concentrations, multivalent ions, dielectric contrasts, and external electric field on the ionic distributions. We observe the presence of non-monotonic ionic density profiles leading to a layered structure in the fluid which is attributed to the competition between electrostatic and steric (entropic) interactions. We find that thermal forces that arise from symmetry breaking at the interfaces can have a profound effect on the ionic structure and can oftentimes overwhelm the influence of the dielectric discontinuity. The combined effect of ionic correlations and inhomogeneous dielectric permittivity significantly changes the character of the effective interaction between the two interfaces.

  14. Boron nitride as two dimensional dielectric: Reliability and dielectric breakdown

    International Nuclear Information System (INIS)

    Boron Nitride (BN) is a two dimensional insulator with excellent chemical, thermal, mechanical, and optical properties, which make it especially attractive for logic device applications. Nevertheless, its insulating properties and reliability as a dielectric material have never been analyzed in-depth. Here, we present the first thorough characterization of BN as dielectric film using nanoscale and device level experiments complementing with theoretical study. Our results reveal that BN is extremely stable against voltage stress, and it does not show the reliability problems related to conventional dielectrics like HfO2, such as charge trapping and detrapping, stress induced leakage current, and untimely dielectric breakdown. Moreover, we observe a unique layer-by-layer dielectric breakdown, both at the nanoscale and device level. These findings may be of interest for many materials scientists and could open a new pathway towards two dimensional logic device applications

  15. Boron nitride as two dimensional dielectric: Reliability and dielectric breakdown

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Yanfeng; Pan, Chengbin; Hui, Fei; Shi, Yuanyuan; Lanza, Mario, E-mail: mlanza@suda.edu.cn [Institute of Functional Nano and Soft Materials, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, 199 Ren-Ai Road, Suzhou 215123 (China); Zhang, Meiyun; Long, Shibing [Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Lian, Xiaojuan; Miao, Feng [National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093 (China); Larcher, Luca [DISMI, Università di Modena e Reggio Emilia, 42122 Reggio Emilia (Italy); Wu, Ernest [IBM Research Division, Essex Junction, Vermont 05452 (United States)

    2016-01-04

    Boron Nitride (BN) is a two dimensional insulator with excellent chemical, thermal, mechanical, and optical properties, which make it especially attractive for logic device applications. Nevertheless, its insulating properties and reliability as a dielectric material have never been analyzed in-depth. Here, we present the first thorough characterization of BN as dielectric film using nanoscale and device level experiments complementing with theoretical study. Our results reveal that BN is extremely stable against voltage stress, and it does not show the reliability problems related to conventional dielectrics like HfO{sub 2}, such as charge trapping and detrapping, stress induced leakage current, and untimely dielectric breakdown. Moreover, we observe a unique layer-by-layer dielectric breakdown, both at the nanoscale and device level. These findings may be of interest for many materials scientists and could open a new pathway towards two dimensional logic device applications.

  16. Cholesterol strongly affects the organization of lipid monolayers studied as models of the milk fat globule membrane: Condensing effect and change in the lipid domain morphology.

    Science.gov (United States)

    Murthy, Appala Venkata Ramana; Guyomarc'h, Fanny; Paboeuf, Gilles; Vié, Véronique; Lopez, Christelle

    2015-10-01

    The biological membrane that surrounds the milk fat globules exhibits phase separation of polar lipids that is poorly known. The objective of this study was to investigate the role played by cholesterol in the organization of monolayers prepared as models of the milk fat globule membrane (MFGM). Differential scanning calorimetry and X-ray diffraction experiments allowed characterization of the gel to liquid crystalline phase transition temperature of lipids, Tm ~35°C, in vesicles prepared with a MFGM lipid extract. For temperature below Tm, atomic force microscopy revealed phase separation of lipids at 30 mN·m(-1) in Langmuir-Blodgett monolayers of the MFGM lipid extract. The high Tm lipids form liquid condensed (LC) domains that protrude by about 1.5 nm from the continuous liquid expanded (LE) phase. Cholesterol was added to the MFGM extract up to 30% of polar lipids (cholesterol/milk sphingomyelin (MSM) molar ratio of 50/50). Compression isotherms evidenced the condensing effect of the cholesterol onto the MFGM lipid monolayers. Topography of the monolayers showed a decrease in the area of the LC domains and in the height difference H between the LC domains and the continuous LE phase, as the cholesterol content increased in the MFGM lipid monolayers. These results were interpreted in terms of nucleation effects of cholesterol and decrease of the line tension between LC domains and LE phase in the MFGM lipid monolayers. This study revealed the major structural role of cholesterol in the MFGM that could be involved in biological functions of this interface (e.g. mechanisms of milk fat globule digestion). PMID:26087463

  17. Dielectric laser accelerators

    Science.gov (United States)

    England, R. Joel; Noble, Robert J.; Bane, Karl; Dowell, David H.; Ng, Cho-Kuen; Spencer, James E.; Tantawi, Sami; Wu, Ziran; Byer, Robert L.; Peralta, Edgar; Soong, Ken; Chang, Chia-Ming; Montazeri, Behnam; Wolf, Stephen J.; Cowan, Benjamin; Dawson, Jay; Gai, Wei; Hommelhoff, Peter; Huang, Yen-Chieh; Jing, Chunguang; McGuinness, Christopher; Palmer, Robert B.; Naranjo, Brian; Rosenzweig, James; Travish, Gil; Mizrahi, Amit; Schachter, Levi; Sears, Christopher; Werner, Gregory R.; Yoder, Rodney B.

    2014-10-01

    The use of infrared lasers to power optical-scale lithographically fabricated particle accelerators is a developing area of research that has garnered increasing interest in recent years. The physics and technology of this approach is reviewed, which is referred to as dielectric laser acceleration (DLA). In the DLA scheme operating at typical laser pulse lengths of 0.1 to 1 ps, the laser damage fluences for robust dielectric materials correspond to peak surface electric fields in the GV /m regime. The corresponding accelerating field enhancement represents a potential reduction in active length of the accelerator between 1 and 2 orders of magnitude. Power sources for DLA-based accelerators (lasers) are less costly than microwave sources (klystrons) for equivalent average power levels due to wider availability and private sector investment. Because of the high laser-to-particle coupling efficiency, required pulse energies are consistent with tabletop microJoule class lasers. Combined with the very high (MHz) repetition rates these lasers can provide, the DLA approach appears promising for a variety of applications, including future high-energy physics colliders, compact light sources, and portable medical scanners and radiative therapy machines.

  18. Experimental observation of electrical instability of droplets on dielectric layer

    International Nuclear Information System (INIS)

    Polydimethylsiloxane (PDMS) has become the most widely used silicon-based organic polymer in bio-MEMS/NEMS devices. However, the inherent hydrophobic nature of PDMS hinders its wide applications in bio-MEMS/NEMS for efficient transport of liquids. Electrowetting is a useful tool to reduce the apparent contact angle of partially wetting conductive liquids and has been utilized widely in bio-MEMS/NEMS. Our experimental results show that the thin PDMS membranes exhibit good properties in electrowetting-on-dielectric. The electrical instability phenomenon of droplets was observed in our experiment. The sessile droplet lying on the PDMS membrane will lose its stability with the touch of the wire electrode to make the apparent contact angle change suddenly larger than 35 deg. Contact mode can protect the dielectric layer from electrical breakdown effectively. Electrical breakdown process of dielectric layer was recorded by a high speed camera. It is found experimentally that a PDMS membrane of 4.8 μm thick will not be destroyed due to the electric breakdown even at 800 V in the contact mode. (fast track communication)

  19. Mechanical property changes in porous low-k dielectric thin films during processing

    International Nuclear Information System (INIS)

    The design of future generations of Cu-low-k dielectric interconnects with reduced electronic crosstalk often requires engineering materials with an optimal trade off between their dielectric constant and elastic modulus. This is because the benefits associated with the reduction of the dielectric constant by increasing the porosity of materials, for example, can adversely affect their mechanical integrity during processing. By using load-dependent contact-resonance atomic force microscopy, the changes in the elastic modulus of low-k dielectric materials due to processing were accurately measured. These changes were linked to alterations sustained by the structure of low-k dielectric films during processing. A two-phase model was used for quantitative assessments of the elastic modulus changes undergone by the organosilicate skeleton of the structure of porous and pore-filled dielectrics.

  20. Mechanical property changes in porous low-k dielectric thin films during processing

    Energy Technology Data Exchange (ETDEWEB)

    Stan, G., E-mail: gheorghe.stan@nist.gov; Gates, R. S. [Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Kavuri, P. [Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Torres, J.; Michalak, D.; Ege, C.; Bielefeld, J.; King, S. W. [Logic Technology Development, Intel Corporation, Hillsboro, Oregon 97124 (United States)

    2014-10-13

    The design of future generations of Cu-low-k dielectric interconnects with reduced electronic crosstalk often requires engineering materials with an optimal trade off between their dielectric constant and elastic modulus. This is because the benefits associated with the reduction of the dielectric constant by increasing the porosity of materials, for example, can adversely affect their mechanical integrity during processing. By using load-dependent contact-resonance atomic force microscopy, the changes in the elastic modulus of low-k dielectric materials due to processing were accurately measured. These changes were linked to alterations sustained by the structure of low-k dielectric films during processing. A two-phase model was used for quantitative assessments of the elastic modulus changes undergone by the organosilicate skeleton of the structure of porous and pore-filled dielectrics.

  1. Dielectric Actuation of Polymers

    Science.gov (United States)

    Niu, Xiaofan

    Dielectric polymers are widely used in a plurality of applications, such as electrical insulation, dielectric capacitors, and electromechanical actuators. Dielectric polymers with large strain deformations under an electric field are named dielectric elastomers (DE), because of their relative low modulus, high elongation at break, and outstanding resilience. Dielectric elastomer actuators (DEA) are superior to traditional transducers as a muscle-like technology: large strains, high energy densities, high coupling efficiency, quiet operation, and light weight. One focus of this dissertation is on the design of DE materials with high performance and easy processing. UV radiation curing of reactive species is studied as a generic synthesis methodology to provide a platform for material scientists to customize their own DE materials. Oligomers/monomers, crosslinkers, and other additives are mixed and cured at appropriate ratios to control the stress-strain response, suppress electromechanical instability of the resulting polymers, and provide stable actuation strains larger than 100% and energy densities higher than 1 J/g. The processing is largely simplified in the new material system by removal of the prestretching step. Multilayer stack actuators with 11% linear strain are demonstrated in a procedure fully compatible with industrial production. A multifunctional DE derivative material, bistable electroactive polymer (BSEP), is invented enabling repeatable rigid-to-rigid deformation without bulky external structures. Bistable actuation allows the polymer actuator to have two distinct states that can support external load without device failure. Plasticizers are used to lower the glass transition temperature to 45 °C. Interpenetrating polymer network structure is established inside the BSEP to suppress electromechanical instability, providing a breakdown field of 194 MV/m and a stable bistable strain as large as 228% with a 97% strain fixity. The application of BSEP

  2. Biofilm development in membrane bioreactors

    OpenAIRE

    Savnik, Veronika

    2010-01-01

    Prevention of biofilm development and its removal has crucial meaning in membrane reactor. Biofilm causes pore blocking on membranes, which causes a drop in efficiency of mixed liquor filtration and consequently deteriorates the efficiency of whole membrane bioreactor. This thesis deals with factors that affect biofilm development in membrane bioreactors. Structure and growth of biofilm are presented from its initial attachment of individual particles, their parameters of adhesion, hydrodynam...

  3. The outer membrane protein Omp35 affects the reduction of Fe(III, nitrate, and fumarate by Shewanella oneidensis MR-1

    Directory of Open Access Journals (Sweden)

    Myers Charles R

    2004-06-01

    Full Text Available Abstract Background Shewanella oneidensis MR-1 uses several electron acceptors to support anaerobic respiration including insoluble species such as iron(III and manganese(IV oxides, and soluble species such as nitrate, fumarate, dimethylsulfoxide and many others. MR-1 has complex branched electron transport chains that include components in the cytoplasmic membrane, periplasm, and outer membrane (OM. Previous studies have implicated a role for anaerobically upregulated OM electron transport components in the use of insoluble electron acceptors, and have suggested that other OM components may also contribute to insoluble electron acceptor use. In this study, the role for an anaerobically upregulated 35-kDa OM protein (Omp35 in the use of anaerobic electron acceptors was explored. Results Omp35 was purified from the OM of anaerobically grown cells, the gene encoding Omp35 was identified, and an omp35 null mutant (OMP35-1 was isolated and characterized. Although OMP35-1 grew on all electron acceptors tested, a significant lag was seen when grown on fumarate, nitrate, and Fe(III. Complementation studies confirmed that the phenotype of OMP35-1 was due to the loss of Omp35. Despite its requirement for wild-type rates of electron acceptor use, analysis of Omp35 protein and predicted sequence did not identify any electron transport moieties or predicted motifs. OMP35-1 had normal levels and distribution of known electron transport components including quinones, cytochromes, and fumarate reductase. Omp35 is related to putative porins from MR-1 and S. frigidimarina as well as to the PorA porin from Neisseria meningitidis. Subcellular fraction analysis confirmed that Omp35 is an OM protein. The seven-fold anaerobic upregulation of Omp35 is mediated post-transcriptionally. Conclusion Omp35 is a putative porin in the OM of MR-1 that is markedly upregulated anaerobically by a post-transcriptional mechanism. Omp35 is required for normal rates of growth on Fe

  4. Conditions affecting the re-alignment of the antimicrobial peptide PGLa in membranes as monitored by solid state 2H-NMR.

    Science.gov (United States)

    Tremouilhac, Pierre; Strandberg, Erik; Wadhwani, Parvesh; Ulrich, Anne S

    2006-09-01

    The cationic antimicrobial peptide PGLa is electrostatically attracted to bacterial membranes, binds as an amphiphilic alpha-helix, and is thus able to permeabilize the lipid bilayer. Using solid state (2)H-NMR of non-perturbing Ala-d(3) labels on the peptide, we have characterized the helix alignment under a range of different conditions. Even at a very high peptide-to-lipid ratio (1:20) and in the presence of negatively charged lipids, there was no indication of a toroidal wormhole structure. Instead, PGLa re-aligns from a surface-bound S-state to an obliquely tilted T-state, which is presumably dimeric. An intermediate structure half-way between the S- and T-state was observed in fully hydrated multilamellar DMPC vesicles at 1:50, suggesting a fast exchange between the two states on the time scale of >50 kHz. We demonstrate that this equilibrium is shifted from the S- towards the T-state either upon (i) increasing the peptide concentration, (ii) adding negatively charged DMPG, or (iii) decreasing the level of hydration. The threshold concentration for re-alignment in DMPC is found to be between 1:200 and 1:100 in oriented samples at 96% humidity. In fully hydrated multilamellar DMPC vesicles, it shifts to an effective peptide-to-lipid ratio of 1:50 as some peptides are able to escape into the bulk water phase. PMID:16716250

  5. The phospholipid-deficient pho1 mutant of Arabidopsis thaliana is affected in the organization, but not in the light acclimation, of the thylakoid membrane.

    Science.gov (United States)

    Härtel, H; Essigmann, B; Lokstein, H; Hoffmann-Benning, S; Peters-Kottig, M; Benning, C

    1998-12-01

    The pho1 mutant of Arabidopsis has been shown to respond to the phosphate deficiency in the leaves by decreasing the amount of phosphatidylglycerol (PG). PG is thought to be of crucial importance for the organization and function of the thylakoid membrane. This prompted us to ask what the consequences of the PG deficiency may be in the pho1 mutant when grown under low or high light. While in the wild-type, the lipid pattern was almost insensitive to changes in the growth light, PG was reduced to 45% under low light in the mutant, and it decreased further to 35% under high light. Concomitantly, sulfoquinovosyl diacylglycerol (SQDG) and to a lesser extent digalactosyl diacylglycerol (DGDG) increased. The SQDG increase correlated with increased amounts of the SQD1 protein, an indicator for an actively mediated process. Despite of alterations in the ultrastructure, mutant thylakoids showed virtually no effects on photosynthetic electron transfer, O2 evolution and excitation energy allocation to the reaction centers. Our results support the idea that PG deficiency can at least partially be compensated for by the anionic lipid SQDG and the not charged lipid DGDG. This seems to be an important strategy to maintain an optimal thylakoid lipid milieu for vital processes, such as photosynthesis, under a restricted phosphate availability. PMID:9858733

  6. Membrane fusion

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    At Stanford University, Boxer lab, I worked on membrane fusion of small unilamellar lipid vesicles to flat membranes tethered to glass surfaces. This geometry closely resembles biological systems in which liposomes fuse to plasma membranes. The fusion mechanism was studied using DNA zippering...... between complementary strands linked to the two apposing membranes closely mimicking the zippering mechanism of SNARE fusion complexes....

  7. Multilayer optical dielectric coating

    Science.gov (United States)

    Emmett, John L.

    1990-01-01

    A highly damage resistant, multilayer, optical reflective coating includes alternating layers of doped and undoped dielectric material. The doping levels are low enough that there are no distinct interfaces between the doped and undoped layers so that the coating has properties nearly identical to the undoped material. The coating is fabricated at high temperature with plasma-assisted chemical vapor deposition techniques to eliminate defects, reduce energy-absorption sites, and maintain proper chemical stoichiometry. A number of differently-doped layer pairs, each layer having a thickness equal to one-quarter of a predetermined wavelength in the material are combined to form a narrowband reflective coating for a predetermined wavelength. Broadband reflectors are made by using a number of narrowband reflectors, each covering a portion of the broadband.

  8. Packing of transmembrane domain 2 of carnitine palmitoyltransferase-1A affects oligomerization and malonyl-CoA sensitivity of the mitochondrial outer membrane protein.

    Science.gov (United States)

    Jenei, Zsuzsanna A; Warren, Gemma Z L; Hasan, Muhammad; Zammit, Victor A; Dixon, Ann M

    2011-12-01

    The purpose of this study was to investigate the sequence-dependence of oligomerization of transmembrane domain 2 (TM2) of rat carnitine palmitoyltransferase 1A (rCPT1A), to elucidate the role of this domain in the function of the full-length enzyme. Oligomerization of TM2 was studied qualitatively using complementary genetic assays that facilitate measurement of helix-helix interactions in the Escherichia coli inner membrane, and multiple quantitative biophysical methods. The effects of TM2-mutations on oligomerization and malonyl-CoA inhibition of the full-length enzyme (expressed in the yeast Pichia pastoris) were quantified. Changes designed to disrupt close-packing of the GXXXG(A) motifs reduced the oligomeric state of the corresponding TM2 peptides from hexamer to trimer (or lower), a reduction also observed on mutation of the TM2 sequence in the full-length enzyme. Disruption of these GXXXG(A) motifs had a parallel effect on the malonyl-CoA sensitivity of rCPT1A, reducing the IC(50) from 30.3 ± 5.0 to 3.0 ± 0.6 μM. For all measurements, wild-type rCPT1A was used as a control alongside various appropriate (e.g., molecular mass) standards. Our results suggest that sequence-determined, TM2-mediated oligomerization is likely to be involved in the modulation of malonyl-CoA inhibition of CPT1A in response to short- and long-term changes in protein-protein and protein-lipid interactions that occur in vivo. PMID:21917985

  9. The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine

    International Nuclear Information System (INIS)

    Deuterium nuclear magnetic resonance (2H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the β-position of the serine moiety ([2-2H]DOPS) or at the 11-position of the acyl chains ([11,11-2H2]DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both [2-2H]DOPS and [11,11-2H2]DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine)100, which were included for reasons of comparison, reveal increased Δvq values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component 2H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. 2H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides

  10. The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine

    Energy Technology Data Exchange (ETDEWEB)

    de Kroon, A.I.P.M.; Killian, J.A.; de Gier, J.; de Kruijff, B. (Univ. of Utrecht (Netherlands))

    1991-01-29

    Deuterium nuclear magnetic resonance ({sup 2}H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the {beta}-position of the serine moiety ((2-{sup 2}H)DOPS) or at the 11-position of the acyl chains ((11,11-{sup 2}H{sub 2})DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both (2-{sup 2}H)DOPS and (11,11-{sup 2}H{sub 2})DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine){sub 100}, which were included for reasons of comparison, reveal increased {Delta}v{sub q} values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component {sup 2}H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. {sup 2}H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides.

  11. Fullerene inhibits benzo(a)pyrene Efflux from Cyprinus carpio hepatocytes by affecting cell membrane fluidity and P-glycoprotein expression.

    Science.gov (United States)

    Chen, Qiqing; Hu, Xialin; Wang, Rui; Yuan, Jin; Yin, Daqiang

    2016-05-01

    P-Glycoprotein (P-gp) can protect cells by pumping out toxic compounds, and has been found widely expressed in fish tissues. Here, we illustrate the P-gp efflux ability for benzo(a)pyrene (BaP) in the hepatocytes of common carp (Cyprinus carpio) after exposing to fullerene aqueous suspension (nC60). The results revealed that nC60 increased the membrane fluidity by decreasing the ratio of saturated to unsaturated fatty acids, and increased the cholesterol contents. These findings, combined with 10-38% and 70-75% down-regulation of P-gp mRNA and protein respectively, suggested that nC60 caused inhibition on P-gp efflux transport system. Therefore, we further investigated the cellular efflux ability for BaP. Results showed unequivocally that nC60 is a potent P-gp inhibitor. The retaining BaP amounts after efflux were elevated by 1.7-2.8 fold during the 10 day exposure. Meanwhile, 5mg/L humic acid (one of the important fractions of natural organic matter, which is ubiquitous in aquatic environment) alleviated the nC60 damage to hepatocytes in terms of oxidative damage, cholesterol increment, and P-gp content reduction; and finally attenuated the suppressed P-gp efflux ability. Collectively, this study provides the first evidence of nC60 toxicity to P-gp functionality in fish and illustrates the possible mechanism of the suppressed P-gp efflux ability for BaP. PMID:26918948

  12. Electric fields inside and outside an anisotropic dielectric sphere

    Institute of Scientific and Technical Information of China (English)

    Li Ying-Le; Wang Ming-Jun

    2009-01-01

    Analytical expressions of electric fields inside and outside an anisotropic dielectric sphere are presented by transforming an anisotropic medium into an isotropic one based on the multi-scale transformation of electromagnetic theory.The theoretical expressions are consistent with those in the literature. The inside electric field, the outside electric field and the angle between their directions are derived in detail. Numerical simulations show that the direction of the outside field influences the magnitude of the inside field, while the dielectric constant tensor greatly affects its direction.

  13. Electromagnetic identification of dielectric materials

    Directory of Open Access Journals (Sweden)

    A. F. Yanenko

    2010-05-01

    Full Text Available The electromagnetic features and parameters of dielectric materials, which are used in light industry and stomatology. The results of measuring are analyzed and the method of authentication is offered.

  14. Nonlinear dielectric response in piezoelectric materials for underwater transducers

    Science.gov (United States)

    Sherlock, N. P.; Garten, L. M.; Zhang, S. J.; Shrout, T. R.; Meyer, R. J.

    2012-12-01

    SONAR transducers based on single crystal lead magnesium niobate-lead titanate (PMNT) have demonstrated improvements over conventional lead zirconate titanate ceramics. Compositional modifications to PMNT have combined the high piezoelectric coefficient (d33 > 2000 pC/N) and electromechanical coupling factor (k33 > 0.90) with the low mechanical losses (QM > 1000) of "hard" piezoelectric ceramics. The dielectric losses of single crystal PMNT have not been investigated as extensively as the mechanical losses but may significantly affect the performance of a device when water loaded. In this work, nonlinearities in the dielectric permittivity and losses have been investigated as a function of applied electric field, measurement frequency, and temperature. It is shown that electromechanically "hard" single crystals offer greater stability of the dielectric properties while maintaining a high permittivity with respect to conventional lead zirconate titanate ceramics.

  15. Open dielectric branes

    International Nuclear Information System (INIS)

    We derive leading terms in the effective actions describing the coupling of bulk supergravity fields to systems of arbitrary numbers of Dp-branes and D(p+4)-branes in type-IIA/IIB string theory. We use these actions to investigate the physics of Dp-D(p+4) systems in the presence of weak background fields. In particular, we construct various solutions describing collections of Dp-branes blown up into open D(p+2)-branes ending on D(p+4)-branes. The configurations are stabilized by the presence of background fields and represent an open-brane analogue of the Myers dielectric effect. To deduce the D-brane actions, we use supersymmetry to derive operators corresponding to moments of various conserved currents in the Berkooz-Douglas matrix model of M-theory in the presence of longitudinal M5-branes and then use dualities to relate these operators to the worldvolume operators appearing in the Dp-D(p+4)-brane effective actions. (author)

  16. Dielectric coated ion thruster

    International Nuclear Information System (INIS)

    This paper describes an ion accelerator apparatus. It comprises: a source of free electrons; a chamber connected to the source of free electrons; means for accelerating the free electrons within the chamber; means for introducing a flow of a gas comprising atoms having a neutral charge into the chamber, the accelerated free electrons colliding with the atoms of the gas causing valence shell electrons to be lost by the atoms, producing therefrom a plasma of positively charged ions; and a metallic grid plate comprising one wall of the chamber and provided with spaced apart perforations extending therethrough, the grid plate being coated on both its inner and outer sides with a layer of an insulating material having a much higher dielectric constant that the metallic grid plate, the grid plate being connected to an electric potential substantially more negative than the positively charged ions so that ions drifting into the vicinity of the metallic grid plate are accelerated toward it, passing out of the chamber through the perforations. The surface of the layer of insulating material on the inner side of the metallic grid plate has an electric potential approximately equal to that of the plasma and thus acting as a screen grid, both layers of insulating material protecting the metallic grid plate from erosion by charged ions and insulating the chamber against thermal and electrical losses

  17. Dielectric and permeability

    Science.gov (United States)

    Cole, K. D.

    1982-01-01

    Using the unabridged Maxwell equations (including vectors D, E and H) new effects in collisionless plasmas are uncovered. In a steady state, it is found that spatially varying energy density of the electric field (E perpendicular) orthogonal to B produces electric current leading, under certain conditions, to the relationship P perpendicular+B(2)/8 pi-epsilon E perpendicular(2)/8 pi = constant, where epsilon is the dielectric constant of the plasma for fields orthogonal to B. In steady state quasi-two-dimensional flows in plasmas, a general relationship between the components of electric field parallel and perpendicular to B is found. These effects are significant in goephysical and astrophysical plasmas. The general conditions for a steady state in collisionless plasma are deduced. With time variations in a plasma, slow compared to ion-gyroperiod, there is a general current, (j*), which includes the well-known polarisation current, given by J*=d/dt (ExM)+(PxB)xB B(-2) where M and P are the magnetization and polarization vectors respectively.

  18. Experimental Studies of Antenna Miniaturization Using Magneto-Dielectric and Dielectric Materials

    OpenAIRE

    Karilainen, Antti O.; Ikonen, Pekka M. T.; Constantin R. Simovski; Tretyakov, Sergei A.; Lagarkov, Andrey N.; Maklakov, Sergei A.; Rozanov, Konstantin N.; Starostenko, Sergey N.

    2009-01-01

    Measurement results for a meandered planar inverted-F antenna (PIFA) loaded with magneto-dielectric and dielectric materials are presented. Figures of merit and ways to compare antennas with different fillings materials are discussed. The used magneto-dielectric material is described, the radiation mechanism of the meandered PIFA is studied, and the proper position for dielectric and magneto-dielectric filling is discussed and identified. Identical-size antennas with dielectric and magneto-di...

  19. Electrical properties and dielectric spectroscopy of Ar+ implanted polycarbonate

    International Nuclear Information System (INIS)

    The aim of the present paper is to study the effect of argon ion implantation on electrical and dielectric properties of polycarbonate. Specimens were implanted with 130 keV Ar+ ions in the fluence ranging from 1×1014 to 1×1016 ions cm−2. The beam current used was ∼0.40 µA cm−2. The electrical conduction behaviour of virgin and Ar+ implanted polycarbonate specimens have been studied through current-voltage (I-V characteristic) measurements. It has been observed that after implantation conductivity increases with increasing ion fluence. The dielectric spectroscopy of these specimens has been done in the frequency range of 100 kHz-100 MHz. Relaxation processes were studied by Cole-Cole plot of complex permittivity (real part of complex permittivity, ε′ vs. imaginary part of complex permittivity, ε″). The Cole-Cole plots have also been used to determine static dielectric constant (εs), optical dielectric constant (ε∞), spreading factor (α), average relaxation time (τ0) and molecular relaxation time (τ). The dielectric behaviour has been found to be significantly affected due to Ar+ implantation. The possible correlation between this behaviour and the changes induced by the implantation has been discussed

  20. Transformation Algorithm of Dielectric Response in Time-Frequency Domain

    Directory of Open Access Journals (Sweden)

    Ji Liu

    2014-01-01

    Full Text Available A transformation algorithm of dielectric response from time domain to frequency domain is presented. In order to shorten measuring time of low or ultralow frequency dielectric response characteristics, the transformation algorithm is used in this paper to transform the time domain relaxation current to frequency domain current for calculating the low frequency dielectric dissipation factor. In addition, it is shown from comparing the calculation results with actual test data that there is a coincidence for both results over a wide range of low frequencies. Meanwhile, the time domain test data of depolarization currents in dry and moist pressboards are converted into frequency domain results on the basis of the transformation. The frequency domain curves of complex capacitance and dielectric dissipation factor at the low frequency range are obtained. Test results of polarization and depolarization current (PDC in pressboards are also given at the different voltage and polarization time. It is demonstrated from the experimental results that polarization and depolarization current are affected significantly by moisture contents of the test pressboards, and the transformation algorithm is effective in ultralow frequency of 10−3 Hz. Data analysis and interpretation of the test results conclude that analysis of time-frequency domain dielectric response can be used for assessing insulation system in power transformer.

  1. Electrowetting on dielectric-based microfluidics for integrated lipid bilayer formation and measurement

    Science.gov (United States)

    Poulos, Jason L.; Nelson, Wyatt C.; Jeon, Tae-Joon; Kim, Chang-Jin ``Cj''; Schmidt, Jacob J.

    2009-07-01

    We present a microfluidic platform for the formation and electrical measurement of lipid bilayer membranes. Using electrowetting on dielectric (EWOD), two or more aqueous droplets surrounded by a lipid-containing organic phase were manipulated into contact to form a lipid bilayer at their interface. Thin-film Ag/AgCl electrodes integrated into the device enabled electrical measurement of membrane formation and the incorporation of gramicidin channels of two bilayers in parallel.

  2. Membrane Potentials Across Hybrid Charged Mosaic Membrane in Organic Solutions%杂化荷电镶嵌膜在有机溶液体系中膜电位

    Institute of Scientific and Technical Information of China (English)

    刘俊生; 徐铜文; 祝熙宇; 傅延勋

    2006-01-01

    Membrane potentials across hybrid charged mosaic membrane in organic solutions were measured. Equilibrium swelling degree (SD) and fixed charge density in both organic solutions and water were also deter mined. Ethylene glycol, ethanol, n-propanol and glycerol were used as organic solutes; meanwhile 0.001mol·dm-3 aqueous KCl solution was utilized as a strong electrolyte to measure the electrical difference. Equilibrium swelling degree indicated that it could be affected by the density of organic solutes; while it enhanced with the increasing density of these solutes. The measurement of fixed charge density showed that the membrane had the maximal absolute value in water among these solvents whether for cationic or anionic groups; the difference of dielectric constant between the water and the organic solutes might be responsible for these change trends. It was confirmed that membrane potentials increased with both the increasing concentration of the organic solutions and the elevated pH values. These results demonstrated that the characteristics of the hybrid charged mosaic membrane could be highly impacted by the properties of the organic solutes. A theoretical model for charged membranes in ternary ion systems of weak electrolyte can be used to explain the above-mentioned phenomena.

  3. Preliminary Research on Relationship Between Dielectric Property and Microstructure of Rabbit Liver

    Institute of Scientific and Technical Information of China (English)

    ZHU Jian-bo; SHI Xue-tao; YOU Fu-sheng; WANG Hang; WANG Hui; CAI Zhan-xiu; DONG Xiu-zhen

    2014-01-01

    The dielectric properties in vitro present characteristic changes along with the alteration of metabolic activities, which can be detected from tissue micro-structure. The dielectric properties of tissues are closely related to its viability, but the relationship remains unclear to us. This study aims to specify the relationship between dielectric parameters and microstructure of living tissues and to try to explain the influence of tissue viability on dielectric properties. Nine rabbits were studied in this experiment. The impedance spectroscopy (10 Hz-1 MHz) and microstructure were determined at different time intervals (from 5 min to 7 h) after samples were prepared. Some characteristic parameters were extracted to analyze the relationship between them. The inactivation process characterized by the microstructurs could be detected by means of dielectric parameters:the microstructures had no obvious change within 30 min and cell swelling caused by osmosis led to the decrease of extracellular ion concentration, resulting in the rise of lowfrequency imped ance after 30 min. The reduction of impedance was accompanied by the expanding intercellular area and irregular cell shape caused by the gradual destruction of cell membrane.The functions between alteration rate of intercellular area and Cole-Cole model parameters were also established. There is a strong correlative relationship between dielectric properties and microstructure. The dielectric spectrum can be a rapid and innocuous method to monitor the status of tissues. In the future, it may be of great help for clinical application, especially in transplantation.

  4. Polaron-electron assisted giant dielectric dispersion in SrZrO3 high-k dielectric

    Science.gov (United States)

    Borkar, Hitesh; Barvat, Arun; Pal, Prabir; Shukla, A. K.; Pulikkotil, J. J.; Kumar, Ashok

    2016-06-01

    The SrZrO3 is a well known high-k dielectric constant (˜22) and high optical bandgap (˜5.8 eV) material and one of the potential candidates for future generation nanoelectronic logic elements (8 nm node technology) beyond silicon. Its dielectric behavior is fairly robust and frequency independent till 470 K; however, it suffers a strong small-polaron based electronic phase transition (Te) linking 650 to 750 K. The impedance spectroscopy measurements revealed the presence of conducting grains and grain boundaries at elevated temperature which provide energetic mobile charge carriers with activation energy in the range of 0.7 to 1.2 eV supporting the oxygen ions and proton conduction. X-ray photoemission spectroscopy measurements suggest the presence of weak non-stoichiometric O2- anions and hydroxyl species bound to different sites at the surface and bulk. These thermally activated charge carriers at elevated temperature significantly contribute to the polaronic based dielectric anomaly and conductivity. Our dielectric anomaly supports pseudo phase transition due to high degree of change in ZrO6 octahedral angle in the temperature range of 650-750 K, where electron density and phonon vibration affect the dielectric and conductivity properties.

  5. Membrane Biophysics

    CERN Document Server

    Ashrafuzzaman, Mohammad

    2013-01-01

    Physics, mathematics and chemistry all play a vital role in understanding the true nature and functioning of biological membranes, key elements of living processes. Besides simple spectroscopic observations and electrical measurements of membranes we address in this book the phenomena of coexistence and independent existence of different membrane components using various theoretical approaches. This treatment will be helpful for readers who want to understand biological processes by applying both simple observations and fundamental scientific analysis. It provides a deep understanding of the causes and effects of processes inside membranes, and will thus eventually open new doors for high-level pharmaceutical approaches towards fighting membrane- and cell-related diseases.

  6. Transferring the PRIMO Coarse-Grained Force Field to the Membrane Environment: Simulations of Membrane Proteins and Helix–Helix Association

    OpenAIRE

    Kar, Parimal; Gopal, Srinivasa Murthy; Cheng, Yi-Ming; Panahi, Afra; Feig, Michael

    2014-01-01

    An extension of the recently developed PRIMO coarse-grained force field to membrane environments, PRIMO-M, is described. The membrane environment is modeled with the heterogeneous dielectric generalized Born (HDGB) methodology that simply replaces the standard generalized Born model in PRIMO without further parametrization. The resulting model was validated by comparing amino acid insertion free energy profiles and application in molecular dynamics simulations of membrane proteins and membran...

  7. Dielectric constant and laser beam propagation in an underdense collisional plasma: effects of electron temperature

    International Nuclear Information System (INIS)

    Dielectric constant and laser beam propagation in an underdense collisional plasma are investigated, using the wave and dielectric function equations, for their dependence on the electron temperature. Simulation results show that, due to the influence of the ponderomotive force there is a nonlinear variation of electron temperature in an underdense collisional plasma, and this leads to a complicated and interesting nonlinear variation of dielectric constant; this nonlinear variation of dielectric constant directly affects the beam propagation and gives rise to laser beam self-focusing in some spatial-temporal regions; in particular, the beam width and the beam intensity present an oscillatory variation in the self-focusing region. The influence of several parameters on the dielectric function and beam self-focusing is discussed.

  8. Dielectric constant and laser beam propagation in an underdense collisional plasma: effects of electron temperature

    Energy Technology Data Exchange (ETDEWEB)

    Xia Xiongping [Department of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Qin Zhen; Xu Bin [Department of Mathematics and Information Sciences, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Cai Zebin, E-mail: xxpccp@yahoo.cn [Department of Basis, Air Force Radar Academy, Wuhan 430019 (China)

    2011-07-01

    Dielectric constant and laser beam propagation in an underdense collisional plasma are investigated, using the wave and dielectric function equations, for their dependence on the electron temperature. Simulation results show that, due to the influence of the ponderomotive force there is a nonlinear variation of electron temperature in an underdense collisional plasma, and this leads to a complicated and interesting nonlinear variation of dielectric constant; this nonlinear variation of dielectric constant directly affects the beam propagation and gives rise to laser beam self-focusing in some spatial-temporal regions; in particular, the beam width and the beam intensity present an oscillatory variation in the self-focusing region. The influence of several parameters on the dielectric function and beam self-focusing is discussed.

  9. Antenna sunshield membrane

    Science.gov (United States)

    Bogorad, Alexander (Inventor); Bowman, Jr., Charles K. (Inventor); Meder, Martin G. (Inventor); Dottore, Frank A. (Inventor)

    1994-01-01

    An RF-transparent sunshield membrane covers an antenna reflector such as a parabolic dish. The blanket includes a single dielectric sheet of polyimide film 1/2-mil thick. The surface of the film facing away from the reflector is coated with a transparent electrically conductive coating such as vapor-deposited indium-tin oxide. The surface of the film facing the reflector is reinforced by an adhesively attached polyester or glass mesh, which in turn is coated with a white paint. In a particular embodiment of the invention, polyurethane paint is used. In another embodiment of the invention, a layer of paint primer is applied to the mesh under a silicone paint, and the silicone paint is cured after application for several days at room temperature to enhance adhesion to the primer.

  10. Oxygen flux and dielectric response study of Mixed Ionic-Electronic Conducting (MIEC) heterogeneous functional materials

    Science.gov (United States)

    Rabbi, Fazle

    Dense mixed ionic-electronic conducting (MIEC) membranes consisting of ionic conductive perovskite-type and/or fluorite-type oxides and high electronic conductive spinel type oxides, at elevated temperature can play a useful role in a number of energy conversion related systems including the solid oxide fuel cell (SOFC), oxygen separation and permeation membranes, partial oxidization membrane reactors for natural gas processing, high temperature electrolysis cells, and others. This study will investigate the impact of different heterogeneous characteristics of dual phase ionic and electronic conductive oxygen separation membranes on their transport mechanisms, in an attempt to develop a foundation for the rational design of such membranes. The dielectric behavior of a material can be an indicator for MIEC performance and can be incorporated into computational models of MIEC membranes in order to optimize the composition, microstructure, and ultimately predict long term membrane performance. The dielectric behavior of the MIECs can also be an indicator of the transport mechanisms and the parameters they are dependent upon. For this study we chose a dual phase MIEC oxygen separation membrane consisting of an ionic conducting phase: gadolinium doped ceria-Ce0.8 Gd0.2O2 (GDC) and an electronic conductive phase: cobalt ferrite-CoFe2O4 (CFO). The membranes were fabricated from mixtures of Nano-powder of each of the phases for different volume percentages, sintered with various temperatures and sintering time to form systematic micro-structural variations, and characterized by structural analysis (XRD), and micro-structural analysis (SEM-EDS). Performance of the membranes was tested for variable partial pressures of oxygen across the membrane at temperatures from 850°C-1060°C using a Gas Chromatography (GC) system. Permeated oxygen did not directly correlate with change in percent mixture. An intermediate mixture 60%GDC-40%CFO had the highest flux compared to the 50%GDC

  11. All-dielectric bianisotropic nanoantennas

    CERN Document Server

    Alaee, Rasoul; Rahimzadegan, Aso; Mirmoosa, Mohammad S; Kivshar, Yuri S; Rockstuhl, Carsten

    2015-01-01

    The study of high-index dielectric nanoparticles and nanoantennas currently attracts a lot of attention. They do not suffer from absorption but promise to provide control on the properties of light comparable to plasmonic nanoantennas. To further advance the field, it is important to identify versatile dielectric nanoantennas with unconventional properties. Here, we show that breaking the symmetry of an all-dielectric nanoantenna leads to a geometrically tunable magneto-electric coupling, i.e. a strong bianisotropy. The suggested nanoantenna exhibits different backscatterings and, as an interesting consequence, different optical scattering forces for opposite illumination directions. An array of such nanoantennas provides different reflection phases when illuminated from opposite directions. With a proper geometrical tuning, this bianisotropic nanoantenna is capable of providing a $2\\pi$ phase change in the reflection spectrum while possessing a rather large and constant amplitude. This allows creating reflec...

  12. Materials Fundamentals of Gate Dielectrics

    CERN Document Server

    Demkov, Alexander A

    2006-01-01

    This book presents materials fundamentals of novel gate dielectrics that are being introduced into semiconductor manufacturing to ensure the continuous scalling of the CMOS devices. This is a very fast evolving field of research so we choose to focus on the basic understanding of the structure, thermodunamics, and electronic properties of these materials that determine their performance in device applications. Most of these materials are transition metal oxides. Ironically, the d-orbitals responsible for the high dielectric constant cause sever integration difficulties thus intrinsically limiting high-k dielectrics. Though new in the electronics industry many of these materials are wel known in the field of ceramics, and we describe this unique connection. The complexity of the structure-property relations in TM oxides makes the use of the state of the art first-principles calculations necessary. Several chapters give a detailed description of the modern theory of polarization, and heterojunction band discont...

  13. High permittivity gate dielectric materials

    CERN Document Server

    2013-01-01

    "The book comprehensively covers all the current and the emerging areas of the physics and the technology of high permittivity gate dielectric materials, including, topics such as MOSFET basics and characteristics, hafnium-based gate dielectric materials, Hf-based gate dielectric processing, metal gate electrodes, flat-band and threshold voltage tuning, channel mobility, high-k gate stack degradation and reliability, lanthanide-based high-k gate stack materials, ternary hafnia and lanthania based high-k gate stack films, crystalline high-k oxides, high mobility substrates, and parameter extraction. Each chapter begins with the basics necessary for understanding the topic, followed by a comprehensive review of the literature, and ultimately graduating to the current status of the technology and our scientific understanding and the future prospects."

  14. Dielectric Bow-tie Nanocavity

    CERN Document Server

    Lu, Qijing; Zou, Chang-Ling

    2013-01-01

    We propose a novel dielectric bow-tie nanocavity consisting of two tip-to-tip opposite triangle semiconductor nanowires, whose end faces are coated by silver nanofilms. Based on the advantages of the dielectric slot and tip structures, and the high reflectivity from the silver mirror, light can be confined in this nanocavity with low loss. We demonstrate that the mode excited in this nanocavity has a deep subwavelength mode volume of 2.8*10^-4 um3 and a high quality factor of 4.9*10^4 (401.3), consequently an ultrahigh Purcell factor of 1.6*10^7 (1.36*10^5), at 4.5 K (300 K) around the resonance wavelength of 1550 nm. This dielectric bow-tie nanocavity may find applications for integrated nanophotonic circuits, such as high-efficiency single photon source, thresholdless nanolaser, and cavity QED strong coupling experiments.

  15. Band-gap tunable dielectric elastomer filter for low frequency noise

    Science.gov (United States)

    Jia, Kun; Wang, Mian; Lu, Tongqing; Zhang, Jinhua; Wang, Tiejun

    2016-05-01

    In the last decades, diverse materials and technologies for sound insulation have been widely applied in engineering. However, suppressing the noise radiation at low frequency still remains a challenge. In this work, a novel membrane-type smart filter, consisting of a pre-stretched dielectric elastomer membrane with two compliant electrodes coated on the both sides, is presented to control the low frequency noise. Since the stiffness of membrane dominates its acoustic properties, sound transmission band-gap of the membrane filter can be tuned by adjusting the voltage applied to the membrane. The impedance tube experiments have been carried out to measure the sound transmission loss (STL) of the filters with different electrodes, membrane thickness and pre-stretch conditions. The experimental results show that the center frequency of sound transmission band-gap mainly depends on the stress in the dielectric elastomer, and a large band-gap shift (more than 60 Hz) can be achieved by tuning the voltage applied to the 85 mm diameter VHB4910 specimen with pre-stretch {λ }0=3. Based on the experimental results and the assumption that applied electric field is independent of the membrane behavior, 3D finite element analysis has also been conducted to calculate the membrane stress variation. The sound filter proposed herein may provide a promising facility to control low frequency noise source with tonal characteristics.

  16. Capacitive Cells for Dielectric Constant Measurement

    Science.gov (United States)

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco

    2015-01-01

    A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

  17. Dielectric Bow-tie Nanocavity

    OpenAIRE

    Lu, Qijing; Shu, Fang-Jie; Zou, Chang-Ling

    2013-01-01

    We propose a novel dielectric bow-tie nanocavity consisting of two tip-to-tip opposite triangle semiconductor nanowires, whose end faces are coated by silver nanofilms. Based on the advantages of the dielectric slot and tip structures, and the high reflectivity from the silver mirror, light can be confined in this nanocavity with low loss. We demonstrate that the mode excited in this nanocavity has a deep subwavelength mode volume of 2.8*10^-4 um3 and a high quality factor of 4.9*10^4 (401.3)...

  18. Membrane Processes.

    Science.gov (United States)

    Pellegrin, Marie-Laure; Burbano, Marie S; Sadler, Mary E; Diamond, Jason; Baker, Simon; Greiner, Anthony D; Arabi, Sara; Wong, Joseph; Doody, Alexandra; Padhye, Lokesh P; Sears, Keith; Kistenmacher, Peter; Kent, Fraser; Tootchi, Leila; Aguinaldo, Jorge; Saddredini, Sara; Schilling, Bill; Min, Kyungnan; McCandless, Robert; Danker, Bryce; Gamage, Neranga P; Wang, Sunny; Aerts, Peter

    2016-10-01

    This review, for literature published in 2015, contains information related to membrane processes for municipal and industrial applications. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following topics: pretreatment, membrane bioreactor (MBR) configuration, design, nutrient removal, operation, industrial treatment, anaerobic membrane systems, reuse, microconstituents removal, membrane technology advances, membrane fouling, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include: Biological Fixed-Film Systems, Activated Sludge and Other Aerobic Suspended Culture Processes, Anaerobic Processes, Water Reclamation and Reuse. The following sections might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants. PMID:27620084

  19. Membrane Processes.

    Science.gov (United States)

    Pellegrin, Marie-Laure; Sadler, Mary E; Greiner, Anthony D; Aguinaldo, Jorge; Min, Kyungnan; Zhang, Kai; Arabi, Sara; Burbano, Marie S; Kent, Fraser; Shoaf, Robert

    2015-10-01

    This review, for literature published in 2014, contains information related to membrane processes for municipal and industrial applications. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following topics: pretreatment, membrane bioreactor (MBR) configuration, design, nutrient removal, operation, industrial treatment, fixed film and anaerobic membrane systems, reuse, microconstituents removal, membrane technology advances, membrane fouling, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include: Biological Fixed-Film Systems, Activated Sludge and Other Aerobic Suspended Culture Processes, Anaerobic Processes, Water Reclamation and Reuse. The following sections might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants. PMID:26420079

  20. Dielectric Resonator Metasurface for Dispersion Engineering

    OpenAIRE

    Achouri, Karim; Yahyaoui, Ali; Gupta, Shulabh; Rmili, Hatem; Caloz, Christophe

    2016-01-01

    We introduce a practical dielectric metasurface design for microwave frequencies. The metasurface is made of an array of dielectric resonators held together by dielectric connections thus avoiding the need of a mechanical support in the form of a dielectric slab and the spurious multiple reflections that such a slab would generate. The proposed design can be used either for broadband metasurface applications or monochromatic wave transformations. The capabilities of the concept to manipulate ...

  1. Dielectric crystal in the Planck blackbody

    CERN Document Server

    Pardy, Miroslav

    2015-01-01

    The dielectric crystal with the index of refraction n is inserted in the Planck blackbody. The spectral formula for photons in such dielectric medium is derived with the equation for the temperature of internal photons. The derived equation is solved for the constant index of refraction. The photon ow initiates the osmotic pressure of he Debye phonons in the dielectric blackbody. Key words: Thermodynamics, blackbody, photons, phonons, dielectric medium, dispersion.

  2. Dielectric response of the human tooth dentine

    Energy Technology Data Exchange (ETDEWEB)

    Leskovec, J. [Dental Clinic, Faculty of Medicine, University of Ljubljana, Hrvatski trg 6, 1104 Ljubljana (Slovenia); Filipic, C. [Jozef Stefan Institute, P.O. Box 3000, 1001 Ljubljana (Slovenia); Levstik, A. [Jozef Stefan Institute, P.O. Box 3000, 1001 Ljubljana (Slovenia)]. E-mail: adrijan.levstik@ijs.si

    2005-07-15

    Dielectric properties of tooth dentine can be well described by the model which was developed for the dielectric response to hydrating porous cement paste. It is shown that the normalized dielectric constant and the normalized specific conductivity are proportional to the model parameters -bar {sub v0} and {sigma}{sub v}, indicating the deposition of AgCl in the dentine tubules during the duration of the precipitation. The fractal dimension of the tooth dentine was determined by dielectric spectroscopy.

  3. Dielectric response of the human tooth dentine

    International Nuclear Information System (INIS)

    Dielectric properties of tooth dentine can be well described by the model which was developed for the dielectric response to hydrating porous cement paste. It is shown that the normalized dielectric constant and the normalized specific conductivity are proportional to the model parameters -bar v0 and σv, indicating the deposition of AgCl in the dentine tubules during the duration of the precipitation. The fractal dimension of the tooth dentine was determined by dielectric spectroscopy

  4. Casimir-Lifshitz interaction between dielectric heterostructures

    International Nuclear Information System (INIS)

    The interaction between arbitrary dielectric heterostructures is studied within the framework of a recently developed dielectric contrast perturbation theory. It is shown that periodically patterned dielectric or metallic structures lead to oscillatory lateral Casimir-Lifshitz forces, as well as modulations in the normal force as they are displaced with respect to one another. The strength of these oscillatory contributions increases with decreasing gap size and increasing contrast in the dielectric properties of the materials used in the heterostructures.

  5. Casimir-Lifshitz interaction between dielectric heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Azari, Arash; Samanta, Himadri S; Golestanian, Ramin [Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH (United Kingdom)], E-mail: r.golestanian@sheffield.ac.uk

    2009-09-15

    The interaction between arbitrary dielectric heterostructures is studied within the framework of a recently developed dielectric contrast perturbation theory. It is shown that periodically patterned dielectric or metallic structures lead to oscillatory lateral Casimir-Lifshitz forces, as well as modulations in the normal force as they are displaced with respect to one another. The strength of these oscillatory contributions increases with decreasing gap size and increasing contrast in the dielectric properties of the materials used in the heterostructures.

  6. Dielectric response of the human tooth dentine

    Science.gov (United States)

    Leskovec, J.; Filipič, C.; Levstik, A.

    2005-07-01

    Dielectric properties of tooth dentine can be well described by the model which was developed for the dielectric response to hydrating porous cement paste. It is shown that the normalized dielectric constant and the normalized specific conductivity are proportional to the model parameters ɛ and σv, indicating the deposition of AgCl in the dentine tubules during the duration of the precipitation. The fractal dimension of the tooth dentine was determined by dielectric spectroscopy.

  7. New steroid molecules affecting membrane proteins

    Czech Academy of Sciences Publication Activity Database

    Kouřilová, Kateřina; Kudová, Eva; Chodounská, Hana; Navrátil, Michal; Konvalinka, Jan; Vyklický ml., Ladislav; Krausová, Barbora

    Praha : Czech Chemical Society, 2014. s. 78. [Liblice 2014. Advances in Organic, Bioorganic and Pharmaceutical Chemistry /49./. 07.11.2014-09.11.2014, Lázně Bělohrad] R&D Projects: GA TA ČR(CZ) TE01020028; GA ČR(CZ) GAP303/12/1464 Institutional support: RVO:61388963 Keywords : NMDAR * steroids Subject RIV: CC - Organic Chemistry

  8. Mechanics of dielectric elastomer-activated deformable transmission grating

    International Nuclear Information System (INIS)

    Laminating a thin layer of elastomeric grating on the surface of a prestretched dielectric elastomer (DE) membrane forms a basic design of electrically tunable transmission grating. We analyze the inhomogeneous deformation of a circular multiple-region configuration. Variation of the geometric and material parameters, as well as of the critical condition determined by loss of tension instability, is probed to aid the design of a DE-based deformable grating. The predicted changes in the grating period agree substantially with the experimental results reported by Aschwanden et al (Aschwanden et al 2007 IEEE Photon. Technol. Lett. 19 1090). (paper)

  9. Dielectric model for Chinese hamster ovary cells obtained by dielectrophoresis cytometry.

    Science.gov (United States)

    Salimi, E; Braasch, K; Butler, M; Thomson, D J; Bridges, G E

    2016-01-01

    We present a dielectric model and its parameters for Chinese hamster ovary (CHO) cells based on a double-shell structure which includes the cell membrane, cytoplasm, nuclear envelope, and nucleoplasm. Employing a dielectrophoresis (DEP) based technique and a microfluidic system, the DEP response of many single CHO cells is measured and the spectrum of the Clausius-Mossotti factor is obtained. The dielectric parameters of the model are then extracted by curve-fitting to the measured spectral data. Using this approach over the 0.6-10 MHz frequency range, we report the values for CHO cells' membrane permittivity, membrane thickness, cytoplasm conductivity, nuclear envelope permittivity, and nucleoplasm conductivity. The size of the cell and its nuclei are obtained using optical techniques. PMID:26858823

  10. Counteracting Gravitation In Dielectric Liquids

    Science.gov (United States)

    Israelsson, Ulf E.; Jackson, Henry W.; Strayer, Donald M.

    1993-01-01

    Force of gravity in variety of dielectric liquids counteracted by imposing suitably contoured electric fields. Technique makes possible to perform, on Earth, variety of experiments previously performed only in outer space and at great cost. Also used similarly in outer space to generate sort of artificial gravitation.

  11. Dielectric waveguide amplifiers and lasers

    NARCIS (Netherlands)

    Pollnau, M.

    2014-01-01

    The performance of semiconductor amplifiers and lasers has made them the preferred choice for optical gain on a micro-chip. In the past few years, we have demonstrated that also rare-earth-ion-doped dielectric waveguides show remarkable performance, ranging from a small-signal gain per unit length o

  12. Inhomogeneous screening near the dielectric interface

    Science.gov (United States)

    Wang, Rui; Wang, Zhen-Gang

    2016-04-01

    Screening is one of the most important concepts in the study of charged systems. Near a dielectric interface, the ion distribution in a salt solution can be highly nonuniform. Here, we develop a theory that self-consistently treats the inhomogeneous screening effects. At higher concentrations when the bulk Debye screening length is comparable to the Bjerrum length, the double layer structure and interfacial properties are significantly affected by the inhomogeneous screening. In particular, the depletion zone is considerably wider than that predicted by the bulk screening approximation or the WKB approximation. The characteristic length of the depletion layer in this regime scales with the Bjerrum length, resulting in a linear increase of the negative adsorption of ions with concentration, in agreement with experiments. For asymmetric salts, inhomogeneous screening leads to enhanced charge separation and surface potential.

  13. Dynamic polarization effects on the angular distributions of protons channeled through carbon nanotubes in dielectric media

    OpenAIRE

    Borka, D.; Mowbray, D. J.; Mišković, Z. L.; Petrović, S.; Nešković, N.

    2008-01-01

    The best level of ordering and straightening of carbon nanotube arrays is often achieved when they are grown in a dielectric matrix, so such structures present the most suitable candidates for future channeling experiments with carbon nanotubes. Consequently, we investigate here how the dynamic polarization of carbon valence electrons in the presence of various surrounding dielectric media affects the angular distributions of protons channeled through (11,~9) single-wall carbon nanotubes. Pro...

  14. Challenges of using dielectric elastomer actuators to tune liquid lens

    Science.gov (United States)

    Keong, Gih-Keong; La, Thanh-Giang; Shiau, Li-Lynn; Tan, Adrian W. Y.

    2014-03-01

    Recently, dielectric elastomer actuators (DEAs) have been adopted to tune liquid membrane lens, just like ciliary muscles do to the lens in human eye. However, it faces some challenges, such as high stress, membrane puncture, high driving voltage requirement, and limited focus distance (not more than 707cm), that limit its practical use. The design problem gets more complex as the liquid lens shares the same elastomeric membrane as the DEA. To address these challenges, we separate DEA from the lens membrane. Instead, a liquid-immersed DEA, which is safe from terminal failure, is used as a diaphragm pump to inflate or deflate the liquid lens by hydraulic pressure. This opens up the possibility that the DEA can be thinned down and stacked up to reduce the driving voltage, independent of the lens membrane thickness. Preliminary study showed that our 8-mm-diameter tunable lens can focus objects in the range of 15cm to 50cm with a small driving voltage of 1.8kV. Further miniaturization of DEA could achieve a driving voltage less than 1kV.

  15. Controlling metamaterial resonances via dielectric and aspect ratio effects

    OpenAIRE

    Chiam, Sher-Yi; Singh, Ranjan; Zhang, Weili; Bettiol, Andrew A

    2010-01-01

    We study ways to enhance the sensitivity and dynamic tuning range of the fundamental inductor-capacitor (LC) resonance in split ring resonators (SRRs) by controlling the aspect ratio of the SRRs and their substrate thickness. We conclude that both factors can significantly affect the LC resonance. We show that metafilms consisting of low height SRRs on a thin substrate are most sensitive to changes in their dielectric environment and thus show excellent potential for sensing applications.

  16. Dielectric barrier discharges in analytical chemistry.

    Science.gov (United States)

    Meyer, C; Müller, S; Gurevich, E L; Franzke, J

    2011-06-21

    The present review reflects the importance of dielectric barrier discharges in analytical chemistry. Special about this discharge is-and in contrast to usual discharges with direct current-that the plasma is separated from one or two electrodes by a dielectric barrier. This gives rise to two main features of the dielectric barrier discharges; it can serve as dissociation and excitation device and as ionization mechanism, respectively. The article portrays the various application fields for dielectric barrier discharges in analytical chemistry, for example the use for elemental detection with optical spectrometry or as ionization source for mass spectrometry. Besides the introduction of different kinds of dielectric barrier discharges used for analytical chemistry from the literature, a clear and concise classification of dielectric barrier discharges into capacitively coupled discharges is provided followed by an overview about the characteristics of a dielectric barrier discharge concerning discharge properties and the ignition mechanism. PMID:21562672

  17. Two-phase mixed media dielectric with macro dielectric beads for enhancing resistivity and breakdown strength

    Science.gov (United States)

    Falabella, Steven; Meyer, Glenn A; Tang, Vincent; Guethlein, Gary

    2014-06-10

    A two-phase mixed media insulator having a dielectric fluid filling the interstices between macro-sized dielectric beads packed into a confined volume, so that the packed dielectric beads inhibit electro-hydrodynamically driven current flows of the dielectric liquid and thereby increase the resistivity and breakdown strength of the two-phase insulator over the dielectric liquid alone. In addition, an electrical apparatus incorporates the two-phase mixed media insulator to insulate between electrical components of different electrical potentials. And a method of electrically insulating between electrical components of different electrical potentials fills a confined volume between the electrical components with the two-phase dielectric composite, so that the macro dielectric beads are packed in the confined volume and interstices formed between the macro dielectric beads are filled with the dielectric liquid.

  18. Introduction of effective dielectric constant to the Poisson-Nernst-Planck model

    Science.gov (United States)

    Sawada, Atsushi

    2016-05-01

    The Poisson-Nernst-Planck (PNP) model has been widely used for analyzing impedance or dielectric spectra observed for dilute electrolytic cells. In the analysis, the behavior of mobile ions in the cell under an external electric field has been explained by a conductive nature regardless of ionic concentrations. However, if the cell has parallel-plate blocking electrodes, the mobile ions may also play a role as a dielectric medium in the cell by the effect of space-charge polarization when the ionic concentration is sufficiently low. Thus the mobile ions confined between the blocking electrodes can have conductive and dielectric natures simultaneously, and their intensities are affected by the ionic concentration and the adsorption of solvent molecules on the electrodes. The balance of the conductive and dielectric natures is quantitatively determined by introducing an effective dielectric constant to the PNP model in the data analysis. The generalized PNP model with the effective dielectric constant successfully explains the anomalous frequency-dependent dielectric behaviors brought about by the mobile ions in dilute electrolytic cells, for which the conventional PNP model fails in interpretation.

  19. Low dielectric constant a-SiOC:H films as copper diffusion barrier

    Science.gov (United States)

    Koh, Yee Wee; Loh, Kian Ping; Rong, Liu; Wee, A. T. S.; Huang, Liu; Sudijono, J.

    2003-01-01

    A low-k dielectric barrier based on silicon oxycarbide for copper damascene processes has been developed in this work. The optimal process conditions that allow the deposition of silicon oxycarbide films with a dielectric constant of 3.74 and copper diffusion depth of 290 Å after thermal stress at 400 °C for 3 h has been identified. Copper diffusion depth is defined as the copper and dielectric interfacial region with three-order magnitude reduction in copper concentration. A multilayered structure consisting of black diamond/SiOC/Cu/TaN/Si is fabricated. 3-methyl silane and oxygen in varying concentration is used for the deposition of SiOC using plasma enhanced chemical vapor deposition. The composition of the films is studied by Fourier transform infrared spectroscopy. Dielectric constant and dielectric breakdown of the films are also evaluated. Secondary ion mass spectrometry is employed to investigate the copper diffusion property of the films. The electronic component of the dielectric constant has been found to be most significant in affecting the overall dielectric constant in SiOC films.

  20. Light-induced interfacial potentials in photoreceptor membranes.

    OpenAIRE

    Cafiso, D S; Hubbell, W L

    1980-01-01

    A rapid change in an interfacial electric potential of isolated bovine rod outer segment disk membranes occurs upon illumination. This potential change, which has been detected by the use of spin-labeled hydrophobic ions, apparently occurs within a low dielectric boundary region of the membrane near the external (cytoplasmic) surface and is positive with respect to the aqueous exterior of the disk. The magnitude of the potential change is pH-and temperature-dependent and appears with a first-...

  1. Optomechanics of Levitated Dielectric Particles

    CERN Document Server

    Yin, Zhang-qi; Li, Tongcang

    2013-01-01

    We review recent works on optomechanics of optically trapped microspheres and nanoparticles in vacuum, which provide an ideal system for studying macroscopic quantum mechanics and ultrasensitive force detection. An optically trapped particle in vacuum has an ultrahigh mechanical quality factor as it is well-isolated from the thermal environment. Its oscillation frequency can be tuned in real time by changing the power of the trapping laser. Furthermore, an optically trapped particle in vacuum may rotate freely, a unique property that does not exist in clamped mechanical oscillators. In this review, we will introduce the current status of optical trapping of dielectric particles in air and vacuum, Brownian motion of an optically trapped particle at room temperature, Feedback cooling and cavity cooling of the Brownian motion. We will also discuss about using optically trapped dielectric particles for studying macroscopic quantum mechanics and ultrasensitive force detection. Applications range from creating macr...

  2. Applications of dielectric elastomer actuators

    Science.gov (United States)

    Pelrine, Ron; Sommer-Larsen, Peter; Kornbluh, Roy D.; Heydt, Richard; Kofod, Guggi; Pei, Qibing; Gravesen, Peter

    2001-07-01

    Dielectric elastomer actuators, based on the field-induced deformation of elastomeric polymers with compliant electrodes, can produce a large strain response, combined with a fast response time and high electromechanical efficiency. This unique performance, combined with other factors such as low cost, suggests many potential applications, a wide range of which are under investigation. Applications that effectively exploit the properties of dielectric elastomers include artificial muscle actuators for robots; low-cost, lightweight linear actuators; solid- state optical devices; diaphragm actuators for pumps and smart skins; acoustic actuators; and rotary motors. Issues that may ultimately determine the success or failure of the actuation technology for specific applications include the durability of the actuator, the performance of the actuator under load, operating voltage and power requirements, and electronic driving circuitry, to name a few.

  3. Dielectric Relaxation of Hexadeutero Dimethylsulfoxide

    Science.gov (United States)

    Betting, H.; Stockhausen, M.

    1999-11-01

    The dielectric relaxation parameters of the title substance (DMSO-d6) in its pure liquid state are determined from meas-urements up to 72 GHz at 20°C in comparison to protonated DMSO. While the relaxation strengths do not differ, the relax-ation time of DMSO-d 6 is significantly longer (21.3 ps) than that of DMSO (19.5 ps).

  4. An investigation into solid dielectrics

    OpenAIRE

    Kleemann, Tobias

    2012-01-01

    Direct measurement techniques for the investigation of electrical processes in solid dielectrics are reviewed and their respective strengths and weaknesses are discussed, particularly the complementary nature of thermally stimulated current measurements. The successful design and construction of a new Thermally Stimulated Discharge Current (TSDC) Spectrometer at the University of Southampton is presented and its correct function validated with experimental measurements of the well known and o...

  5. Electromagnetic flowmeter for dielectric liquids.

    OpenAIRE

    Amare, T.

    1995-01-01

    Experimental investigation and theoretical analysis of an electromagnetic flowmeter designed for use with dielectric liquids has been carried out. An extensive survey of the industrial users of flowmeters has been made, involving the participation of over 47 companies, which provides information about the current industrial use, attitudes and attributes of electromagnetic and other types of flowmeters. The design of the flowmeter is mainly concerned with overcoming the charge n...

  6. Dielectric-filled radiofrequency linacs

    International Nuclear Information System (INIS)

    High current, high brightness electron beam accelerators promise to open up dramatic new applications. Linear induction accelerators are currently viewed as the appropriate technology for these applications. A concept by Humphries and Hwang may permit radiofrequency accelerators to fulfill the same functions with greater simplicity and enhanced flexibility. This concept involves the replacement of vacuum rf cavities with dielectric filled ones. Simple analysis indicates that the resonant frequencies are reduced by a factor of (ε0/ε)1/2 while the stored energy is increased by ε/ε0. For a high dielectric constant like water, this factor can approach 80. A series of numerical calculations of simple pill-box cavities was performed. Eigenfunctions and resonant frequencies for a full system configuration, including dielectric material, vacuum beamline, and a ceramic window separating the two have been computed. These calculations are compared with the results of a small experimental cavity which have been constructed and operated. Low power tests show excellent agreement. (author). 4 figs., 8 refs

  7. Dielectric decrement effects in electrokinetics

    Science.gov (United States)

    Figliuzzi, Bruno; Chan, Wai Hong Ronald; Buie, Cullen; Moran, Jeffrey

    2015-11-01

    Understanding the nonlinear phenomena that occur in the electric double layer (EDL) that forms at charged surfaces is a key issue in electrokinetics. In recent studies, Nakayama and Andelman [J. Chem. Physics 2015] Hatlo et al. [EPL 2012], and Zhao and Zhai [JFM 2013] demonstrated that dielectric decrement significantly influences the ionic concentration in the electric double layer (EDL) at high zeta potential, leading to the formation of a condensed layer near the particle's surface. In this presentation, we apply the dielectric decrement model to study two archetypal problems in electrokinetics, namely the electrophoresis of particles with fixed surface charges and the electrophoresis of ideally polarizable particles. Our aim is to rely on numerical simulations to incorporate nonlinear effects including crowding effects due to the finite size of ions, dielectric decrement in the EDL, surface conduction, concentration polarization and advection in the bulk solution. In parallel, we derive a simplified composite layer model that enables us to obtain analytical estimates of the physical quantities involved in the physical description of the problem.

  8. Giant dielectric response and low dielectric loss in Al2O3 grafted CaCu3Ti4O12 ceramics

    International Nuclear Information System (INIS)

    This study sheds light on the effect of alumina on dielectric constant and dielectric loss of novel CaCu3Ti4O12 composite ceramics. Alumina, at several concentrations, was deposited on the surface of CaCu3Ti4O12 particles via sol-gel technique. The dielectric constant significantly increased for all frequencies and the dielectric loss substantially decreased for low and intermediate frequencies. These observations were attributed to the change in characteristics of grains and grain boundaries. It was found that the insulating properties of the grain boundaries are improved following the addition of Al2O3. The relative density of CaCu3Ti4O12/Al2O3 composite ceramics decreased compared to the pure CaCu3Ti4O12 and the grain size was greatly changed with the alumina content affecting the dielectric properties. With the addition of alumina into CaCu3Ti4O12, tighter interfaces formed. The 6%- and 10%-alumina ceramics showed the minimum dielectric loss and the maximum dielectric constant, respectively. Both the dielectric constant and loss tangent decreased in the 20%-alumina ceramic due to the formation of CuO secondary phase. It was revealed that Al serves as an electron acceptor decreasing the electron concentration, if Al3+ ions substitute for Ti4+ ions, and as an electron donor increasing the electron concentration, if Al3+ ions substitute for Ca2+ ions. We established a processing-microstructure-properties paradigm which opens new avenues for novel applications of CaCu3Ti4O12/Al2O3 composite ceramics

  9. Dielectric investigations of vanadium modified barium zirconium titanate ceramics obtained from mixed oxide method

    Energy Technology Data Exchange (ETDEWEB)

    Moura, F. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica Universidade Estadual Paulista, Bairro Quitandinha, CEP 14800-900, Araraquara, SP (Brazil); Simoes, A.Z. [Universidade Federal de Itajuba - Unifei - Campus Itabira, Rua Sao Paulo 377, Bairro Amazonas - Itabira-MG, CEP 35900-373 (Brazil)], E-mail: alezipo@yahoo.com; Aguiar, E.C.; Nogueira, I.C.; Zaghete, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica Universidade Estadual Paulista, Bairro Quitandinha, CEP 14800-900, Araraquara, SP (Brazil)

    2009-06-24

    Vanadium modified barium zirconium titanate ceramics Ba(Zr{sub 0.10}Ti{sub 0.90})O{sub 3}:2V (BZT:2V) were prepared from the mixed oxide method. According to X-ray diffraction analysis, addition of vanadium leads to ceramics free of secondary phases. Electrical characteristics reveal a dielectric permittivity at around 15,000 with low dielectric loss with a remnant polarization (P{sub r}) of 8 {mu}C/cm{sup 2} at 2 kV/cm. From the obtained results, we assume that vanadium substitution in the BZT lattice affects dielectric characteristics due to the electron-relaxation-mode in which carriers (polarons, protons, and so on) are coupled with existing dielectric modes.

  10. Dielectric investigations of vanadium modified barium zirconium titanate ceramics obtained from mixed oxide method

    International Nuclear Information System (INIS)

    Vanadium modified barium zirconium titanate ceramics Ba(Zr0.10Ti0.90)O3:2V (BZT:2V) were prepared from the mixed oxide method. According to X-ray diffraction analysis, addition of vanadium leads to ceramics free of secondary phases. Electrical characteristics reveal a dielectric permittivity at around 15,000 with low dielectric loss with a remnant polarization (Pr) of 8 μC/cm2 at 2 kV/cm. From the obtained results, we assume that vanadium substitution in the BZT lattice affects dielectric characteristics due to the electron-relaxation-mode in which carriers (polarons, protons, and so on) are coupled with existing dielectric modes.

  11. Dielectric properties of doped Bi12SiO20 crystals

    International Nuclear Information System (INIS)

    The dielectric permeability and dielectric losses in crystals of Bi12SiO20 doped with Mn, Cr, Co, Ni, Fe and Cr+Al have been studied as a function of the electric field frequency in the range 103 to 106 Hz at room temperature. Doping with Co, Ni and Cr+Al does not affect significantly the dielectric properties. The dielectric permeability ε of Mn and Cr-doped crystals increases in value but the general frequency trend remains unchanged, while Fe doping results in lower ε values in the whole frequency range. The tgδ frequency dependence is interpreted as evidence of creation of various deep level traps. 2 figs., 8 refs

  12. Structural and dielectric properties of yttrium-substituted hydroxyapatites

    International Nuclear Information System (INIS)

    Hydroxyapatite (HAp) samples doped with 0, 2 and 4 at.% of yttrium (Y) were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy attached with energy dispersive X-ray (EDX) spectroscopy, antimicrobial activity tests and dielectric studies. The hydroxyl groups observed in FTIR spectra confirmed the formation of HAp phase in the studied samples. The crystallite size, crystallinity degree and lattice parameters of the samples were changed with Y content. The volume of the unit cell was gradually decreased with the addition of Y. Undoped and Y-containing HAp samples were screened to determine their in vitro antimicrobial activities against the standard strains. It was found that no samples have any antimicrobial effect. The relative dielectric permittivity and dielectric loss are affected by Y content. While the alternating current conductivity increases with increasing frequency, it decreases with increasing Y content. - Highlights: • The lattice parameters and crystal size are affected by Y content. • The volume of the unit cell was gradually decreased with the addition of Y. • No samples have any antimicrobial effect. • The alternating current conductivity decreases with increasing Y content

  13. Dielectric behavior of semiconductors at microwave frequencies

    Science.gov (United States)

    Dahiya, Jai N.

    1992-01-01

    A cylindrical microwave resonant cavity in TE(011) (Transverse Electric) mode is used to study the dielectric relaxation in germanium and silicon. The samples of these semiconductors are used to perturb the electric field in the cavity, and Slater's perturbation equations are used to calculate the real and imaginary parts of the dielectric constant. The dielectric loss of germanium and silicon is studied at different temperatures, and Debye's equations are used to calculate the relaxation time at these temperatures.

  14. Test results of a prototype dielectric microcalorimeter

    Science.gov (United States)

    Pfafman, T. E.; Silver, E.; Labov, S.; Beeman, J.; Goulding, F.; Hansen, W.; Landis, D.; Madden, N.

    1990-01-01

    The initial development work on a dielectric microcalorimeter is presented. It focuses on the dielectric properties of the ferroelectric material KTa(1-x)Nb(x)O3 (KTN). Measurements of the temperature dependent dielectric constant are given together with the first alpha particle detection results from a prototype composite microcalorimeter operating at 1.3 K. A nonthermal mechanism for detecting 6 MeV alpha particles in a monolithic KTN sample is also reported.

  15. Terahertz-frequency dielectric response of liquids

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Møller, Uffe; Cooke, David

    -induced dipole moments. In the polar liquid water the fastest relaxational dynamics is found at terahertz frequencies, just below the first intermolecular vibrational and librational modes. In this presentation we will discuss optical terahertz spectroscopic techniques for measurement of the full dielectric...... function of liquids at terahertz frequencies. We will review the current understanding of the high-frequency dielectric spectrum of water, and discuss the relation between the dielectric spectrum and the thermodynamic properties of certain aqueous solutions....

  16. Graphene-Dielectric Integration for Graphene Transistors

    OpenAIRE

    Liao, Lei; Duan, Xiangfeng

    2010-01-01

    Graphene is emerging as an interesting electronic material for future electronics due to its exceptionally high carrier mobility and single-atomic thickness. Graphene-dielectric integration is of critical importance for the development of graphene transistors and a new generation of graphene based electronics. Deposition of dielectric materials onto graphene is of significant challenge due to the intrinsic material incompatibility between pristine graphene and dielectric oxide materials. Here...

  17. The effect of acute microgravity on mechanically-induced membrane damage and membrane-membrane fusion events

    Science.gov (United States)

    Clarke, M. S.; Vanderburg, C. R.; Feeback, D. L.; McIntire, L. V. (Principal Investigator)

    2001-01-01

    Although it is unclear how a living cell senses gravitational forces there is no doubt that perturbation of the gravitational environment results in profound alterations in cellular function. In the present study, we have focused our attention on how acute microgravity exposure during parabolic flight affects the skeletal muscle cell plasma membrane (i.e. sarcolemma), with specific reference to a mechanically-reactive signaling mechanism known as mechanically-induced membrane disruption or "wounding". Both membrane rupture and membrane resealing events mediated by membrane-membrane fusion characterize this response. We here present experimental evidence that acute microgravity exposure can inhibit membrane-membrane fusion events essential for the resealing of sarcolemmal wounds in individual human myoblasts. Additional evidence to support this contention comes from experimental studies that demonstrate acute microgravity exposure also inhibits secretagogue-stimulated intracellular vesicle fusion with the plasma membrane in HL-60 cells. Based on our own observations and those of other investigators in a variety of ground-based models of membrane wounding and membrane-membrane fusion, we suggest that the disruption in the membrane resealing process observed during acute microgravity is consistent with a microgravity-induced decrease in membrane order.

  18. Research of Dielectric Breakdown Micro fluidic Sampling Chip

    International Nuclear Information System (INIS)

    Micro fluidic chip is mainly driven electrically by external electrode and array electrode, but there are certain disadvantages in both of ways, which affect the promotion and application of micro fluidic technology. This paper discusses a scheme that uses the conductive solution in a microchannel made by PDMS, replacing electrodes and the way of dielectric breakdown to achieve microfluidic chip driver. It could reduce the driving voltage and simplify the chip production process. To prove the feasibility of this method, we produced a micro fluidic chip used in PDMS material with the lithography technology and experimented it. The results showed that using the dielectric breakdown to achieve microfluidic chip driver is feasible, and it has certain application prospect.

  19. Dielectric Resonator Metasurface for Dispersion Engineering

    CERN Document Server

    Achouri, Karim; Gupta, Shulabh; Rmili, Hatem; Caloz, Christophe

    2016-01-01

    We introduce a practical dielectric metasurface design for microwave frequencies. The metasurface is made of an array of dielectric resonators held together by dielectric connections thus avoiding the need of a mechanical support in the form of a dielectric slab and the spurious multiple reflections that such a slab would generate. The proposed design can be used either for broadband metasurface applications or monochromatic wave transformations. The capabilities of the concept to manipulate the transmission phase and amplitude of the metasurface are supported by numerical and experimental results. Finally, a half-wave plate and a quarter-wave plate have been realized with the proposed concept.

  20. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on dipolar copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede; Hvilsted, Søren; Skov, Anne Ladegaard

    2014-01-01

    Dielectric elastomers (DES) are a promising new transducer technology, but high driving voltages limit their current commercial potential. One method used to lower driving voltage is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric permi...

  1. Axionic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Aurilia, A. (Dept. of Physics, California State Polytechnic Univ., Pomona, CA (United States)); Spallucci, E. (Dipt. di Fisica Teorica, Univ. Trieste (Italy) INFN, Sezione Trieste (Italy))

    1992-05-21

    A metal ring removed from a soap-water solution encloses a film of soap which can be mathematically described as a minimal surface having the ring as its only boundary. This is known to everybody. In this letter we suggest a relativistic extension of the above fluidodynamic system where the soap film is replaced by a Kalb-Ramand gauge potential B{sub {mu}{nu}}(x) and the ring by a closed string. The interaction between the B{sub {mu}{nu}} field and the string current excites a new configuration of the system consisting of a relativistic membrane bounded by the string. We call such a classical solution of the equation of motion an axionic membrane. As a dynamical system, the axionic membrane admits a Hamilton-Jacobi formulation which is an extension of the HJ theory of electromagnetic strings. (orig.).

  2. Dielectric strength of parylene HT

    International Nuclear Information System (INIS)

    The dielectric strength of parylene HT (PA-HT) films was studied at room temperature in a wide thickness range from 500 nm to 50 μm and was correlated with nano- and microstructure analyses. X-ray diffraction and polarized optical microscopy have revealed an enhancement of crystallization and spherulites development, respectively, with increasing the material thickness (d). Moreover, a critical thickness dC (between 5 and 10 μm) is identified corresponding to the beginning of spherulite developments in the films. Two distinct behaviors of the dielectric strength (FB) appear in the thickness range. For d ≥ dC, PA-HT films exhibit a decrease in the breakdown field following a negative slope (FB ∼ d−0.4), while for d C, it increases with increasing the thickness (FB ∼ d0.3). An optimal thickness doptim ∼ 5 μm corresponding to a maximum dielectric strength (FB ∼ 10 MV/cm) is obtained. A model of spherulite development in PA-HT films with increasing the thickness is proposed. The decrease in FB above dC is explained by the spherulites development, whereas its increase below dC is induced by the crystallites growth. An annealing of the material shows both an enhancement of FB and an increase of the crystallites and spherulites dimensions, whatever the thickness. The breakdown field becomes thickness-independent below dC showing a strong influence of the nano-scale structural parameters. On the contrary, both nano- and micro-scale structural parameters appear as influent on FB for d ≥ dC

  3. Dielectric strength of parylene HT

    Energy Technology Data Exchange (ETDEWEB)

    Diaham, S., E-mail: sombel.diaham@laplace.univ-tlse.fr; Bechara, M.; Locatelli, M.-L.; Khazaka, R. [Université de Toulouse, UPS, INPT, LAPLACE, 118 route de Narbonne-Bât. 3R3, F-31062 Toulouse Cedex 9 (France); CNRS, LAPLACE, F-31062 Toulouse (France); Tenailleau, C. [Université de Toulouse, UPS, Laboratoire CIRIMAT/LCMIE, 118 route de Narbonne-Bât. 2R1, F-31062 Toulouse Cedex 9 (France); Kumar, R. [Speciality Coating Systems, Inc. (SCS), Cookson Electronics, 7645 Woodland Drive, Indianapolis, Indiana 46278 (United States)

    2014-02-07

    The dielectric strength of parylene HT (PA-HT) films was studied at room temperature in a wide thickness range from 500 nm to 50 μm and was correlated with nano- and microstructure analyses. X-ray diffraction and polarized optical microscopy have revealed an enhancement of crystallization and spherulites development, respectively, with increasing the material thickness (d). Moreover, a critical thickness d{sub C} (between 5 and 10 μm) is identified corresponding to the beginning of spherulite developments in the films. Two distinct behaviors of the dielectric strength (F{sub B}) appear in the thickness range. For d ≥ d{sub C}, PA-HT films exhibit a decrease in the breakdown field following a negative slope (F{sub B} ∼ d{sup −0.4}), while for d < d{sub C}, it increases with increasing the thickness (F{sub B} ∼ d{sup 0.3}). An optimal thickness d{sub optim} ∼ 5 μm corresponding to a maximum dielectric strength (F{sub B} ∼ 10 MV/cm) is obtained. A model of spherulite development in PA-HT films with increasing the thickness is proposed. The decrease in F{sub B} above d{sub C} is explained by the spherulites development, whereas its increase below d{sub C} is induced by the crystallites growth. An annealing of the material shows both an enhancement of F{sub B} and an increase of the crystallites and spherulites dimensions, whatever the thickness. The breakdown field becomes thickness-independent below d{sub C} showing a strong influence of the nano-scale structural parameters. On the contrary, both nano- and micro-scale structural parameters appear as influent on F{sub B} for d ≥ d{sub C}.

  4. Superbackscattering from single dielectric particles

    Science.gov (United States)

    Liberal, Iñigo; Ederra, Iñigo; Gonzalo, Ramón; Ziolkowski, Richard W.

    2015-07-01

    We demonstrate that superbackscattering responses can be excited in subwavelength dielectric particles with simple geometries. The superbackscattering response arises from the simultaneous, coherent excitation of electric dipole and magnetic quadrupole resonances. Its signature is a superdirective scattering pattern simultaneously pointing towards both the forward and backward directions. The practical implementation of this effect with Tellurium particles operating in the thermal infrared is also addressed. The examples presented reveal that spherical resonators outperform array-based superbackscatterers in terms of the backscattering peak, compact size, robustness against losses and isotropic response.

  5. The Dielectric Properties of Poly

    Science.gov (United States)

    Bello, Alfredo

    The dielectric properties of poly(vinylidene fluoride) (PVF(,2)) are discussed in this work. A review of the literature concerning the five known dielectric relaxations of PVF(,2) is presented and the general theory of dielectric relaxations in polymers is summarized. The real and imaginary parts of the dielectric constant of several samples of PVF(,2) were measured as a function of frequency, temperature and pressure. In the temperature experiment covering the range from 5 K to 380 K at five audio frequencies (100 Hz to 10 KHz), four relaxations were found: (alpha), (beta), (delta) and (epsilon). The (alpha) relaxation at temperatures between 345 and 370 K at 1000 Hz, was found to be dependent on the history and preparation method of the sample and also to have a Debye like behavior. The (beta) relaxation around 250 K at 1000 Hz was found to be related to the glass transition of PVF(,2) and its behavior is parametrized by using the Williams-Landel-Ferry (WLF) model. The (delta) relaxation around 76 K at 1000 Hz was found to be Debye like and associated with the (alpha)-phase of PVF(,2). The (epsilon) relaxation was found in (beta)-phase PVF(,2) at 14.5 K at 1000 Hz. Evidence of the relaxation was found also in (alpha)-phase PVF(,2). In the pressure experiments the (beta) relaxation was studied in the temperature range from 240 to 360 K and at pressures from 0.0001 to 0.6 GPa. The behavior was explained by using the WLF free volume model and comparison between the calculated glass transition temperature parameter in the WLF equation and the experimental peak temperature is made. It was found that even though the WLF equation mathematically describes the (beta) relaxation, the T(,g) parameter does not represent the real transition temperature behavior with pressure. The peak temperature of the (beta) relaxation, was found to be a better guide to the behavior of the real T(,g).

  6. Ferroelectric dielectrics integrated on silicon

    CERN Document Server

    Defay, Emmanuel

    2013-01-01

    This book describes up-to-date technology applied to high-K materials for More Than Moore applications, i.e. microsystems applied to microelectronics core technologies.After detailing the basic thermodynamic theory applied to high-K dielectrics thin films including extrinsic effects, this book emphasizes the specificity of thin films. Deposition and patterning technologies are then presented. A whole chapter is dedicated to the major role played in the field by X-Ray Diffraction characterization, and other characterization techniques are also described such as Radio frequency characterizat

  7. Dispersive optomechanics: a membrane inside a cavity

    International Nuclear Information System (INIS)

    We present the results of theoretical and experimental studies of dispersively coupled (or 'membrane in the middle') optomechanical systems. We calculate the linear optical properties of a high finesse cavity containing a thin dielectric membrane. We focus on the cavity's transmission, reflection and finesse as a function of the membrane's position along the cavity axis and as a function of its optical loss. We compare these calculations with measurements and find excellent agreement in cavities with empty-cavity finesses in the range 104-105. The imaginary part of the membrane's index of refraction is found to be ∼10-4. We calculate the laser cooling performance of this system, with a particular focus on the less-intuitive regime in which photons 'tunnel' through the membrane on a timescale comparable to the membrane's period of oscillation. Lastly, we present calculations of quantum non-demolition measurements of the membrane's phonon number in the low signal-to-noise regime where the phonon lifetime is comparable to the QND readout time.

  8. Mechanism of Fe crud deposition by membrane electrification in hollow fiber membrane filter

    International Nuclear Information System (INIS)

    The hollow fiber membrane filter (HFF) applied to the condensate polishing system in BWR plants occasionally experiences a greater pressure drop due to fouling of the membrane inner surface. Then a mechanism for fouling and its countermeasures were studied from simulated laboratory experiments. The HFF made of polyethylene polymer which has a dielectric property became negatively charged on its surface when pure water, such as condensate, flowed through the filter. The degree of the negative charge depended on the water electrical conductivity and flow velocity through the membrane. The amount of Fe hydroxide deposits on the membrane surface depended on the Fe and Cu ion concentrations. Then a crud precoating method was confirmed as an effective and practicable means to restrict deposits. (author)

  9. Membrane curvature enables N-Ras lipid anchor sorting to liquid-ordered membrane phases

    DEFF Research Database (Denmark)

    Larsen, Jannik Bruun; Jensen, Martin Borch; Bhatia, Vikram Kjøller;

    2015-01-01

    Trafficking and sorting of membrane-anchored Ras GTPases are regulated by partitioning between distinct membrane domains. Here, in vitro experiments and microscopic molecular theory reveal membrane curvature as a new modulator of N-Ras lipid anchor and palmitoyl chain partitioning. Membrane...... curvature was essential for enrichment in raft-like liquid-ordered phases; enrichment was driven by relief of lateral pressure upon anchor insertion and most likely affects the localization of lipidated proteins in general....

  10. Robotic membranes

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette

    2008-01-01

    prototypes, Vivisection and Strange Metabolisms, were developed at the Centre for Information Technology and Architecture (CITA) at the Royal Danish Academy of Fine Arts in Copenhagen as a means of engaging intangible digital data with tactile physical material. As robotic membranes, they are a dual...

  11. A simple method for reducing inevitable dielectric loss in high-permittivity dielectric elastomers

    Science.gov (United States)

    Madsen, F. B.; Yu, L.; Mazurek, P.; Skov, A. L.

    2016-07-01

    Commercial viability of dielectric elastomers (DEs) is currently limited by a few obstacles, including high driving voltages (in the kV range). Driving voltage can be lowered by either decreasing the Young’s modulus or increasing the dielectric permittivity of silicone elastomers, or a combination thereof. A decrease in the Young’s modulus, however, is often accompanied by a loss in mechanical stability, whereas increases in dielectric permittivity are usually followed by a large increase in dielectric loss followed by a decrease in breakdown strength and thereby the lifetime of the DE. A new soft elastomer matrix, with high dielectric permittivity and a low Young’s modulus, aligned with no loss of mechanical stability, was prepared through the use of commercially available chloropropyl-functional silicone oil mixed into a tough commercial liquid silicone rubber silicone elastomer. The addition of chloropropyl-functional silicone oil in concentrations up to 30 phr was found to improve the properties of the silicone elastomer significantly, as dielectric permittivity increased to 4.4, dielectric breakdown increased up to 25% and dielectric losses were reduced. The chloropropyl-functional silicone oil also decreased the dielectric losses of an elastomer containing dielectric permittivity-enhancing TiO2 fillers. Commercially available chloropropyl-functional silicone oil thus constitutes a facile method for improved silicone DEs, with very low dielectric losses.

  12. All-dielectric metasurface for optical focusing

    NARCIS (Netherlands)

    Pisano, E.; Silvestri, F.; Gerini, G.; Lancellotti, V.; Galdi, V.

    2015-01-01

    We propose the design of a dielectric flat lens for visible wavelengths, capable of efficiently focus the incident field at a given distance. Our approach relies on the recently proposed exploitation of high-index dielectric resonators with spectrally overlapping electric and magnetic dipole resonan

  13. Fullerene derivatives with increased dielectric constants

    NARCIS (Netherlands)

    Jahani, Fatemeh; Torabi, Solmaz; Chiechi, Ryan C; Koster, L Jan Anton; Hummelen, Jan C

    2014-01-01

    The invention of new organic materials with high dielectric constants is of extreme importance for the development of organic-based devices such as organic solar cells. We report on a synthetic way to increase the dielectric constant of fullerene derivatives. It is demonstrated that introducing trie

  14. Aging of Dielectric Properties below Tg

    DEFF Research Database (Denmark)

    Olsen, Niels Boye; Dyre, Jeppe; Christensen, Tage Emil

    The dielectric loss at 1Hz in TPP is studied during a temperature step from one equilibrium state to another. In the applied cryostate the temperature can be equilibrated on a timescale of 1 second. The aging time dependence of the dielectric loss is studied below Tg applying temperature steps in...

  15. Microwave dielectric method for moisture sensing almonds

    Science.gov (United States)

    A dielectric –based method was developed for rapid and nondestructive determination of moisture content in almond kernels independent of bulk density from measurement of their dielectric properties at a single microwave frequency. Calibration equations for moisture determination with temperature com...

  16. Torus-like Dielectric D2-brane

    OpenAIRE

    Hyakutake, Yoshifumi

    2001-01-01

    We find new solutions corresponding to torus-like generalization of dielectric D2-brane from the viewpoint of D2-brane action and N D0-branes one. These are meta-stable and would decay to the spherical dielectric D2-brane.

  17. Microwave device for liquid dielectrics diagnostics

    OpenAIRE

    Safonov, V. V.

    2010-01-01

    It is developed a method for measuring of dielectric permittivity of liquid dielectrics. High accuracy and reliability of the method is provided by definite hardware realization; it is used resonance-bridge method; to provide high stability of measuring SHF signal frequency there is used self-excited oscillator on a basis of active running wave resonator.

  18. Dielectrical properties of composites LDPE+CB

    Directory of Open Access Journals (Sweden)

    Škipina Blanka

    2010-01-01

    Full Text Available There is currently great interest in the technological properties of conductive polymer composites because their cost-performance balance. They have a wide range of industrial applications -in anti-static materials, self regulating heaters, current overload and overheating protection devices, and materials for electromagnetic radiation shielding. Measurements of the electrical properties of polymer composites are one of the most convenient and sensitive methods for studying polymer structure. A polymer composite differs substantially from a free polymer in a wide range of properties. The presence of filler affects both the electrical, as well as mechanical properties. One of the most important characteristics of conductive polymer composites is that their electrical conductivity increases nonlinearly with the increase of the concentration of filler particles. When the concentration of filler particles reaches a certain critical value, a drastic transition from an electrical insulator to a conductor is exhibited. This conductivity behavior resulting in a sudden insulator-conductor transition is ascribed to a percolation process, and the critical filler concentration at which the conductivity jump occurs is called ‘percolation threshold’. In the past few years, a lot of studies have been carried out to analyze the percolation phenomenon and mechanisms of the conductive behavior in conductive polymer composites. It has been established that the electrical conductivity of conductive polymer composites uncommonly depends on the temperature. Some of such composites show a sharp increase and/or decrease in electrical conductivity at specific temperatures. The conductive temperature coefficient (CTC of conductive polymer composites has been widely investigated. In these work we investigated how concentration of the CB affects the dielectrical properties of the composite LDPE+CB. The ac electrical conductivity, σac, for such composites was measured

  19. Microscopic resolution broadband dielectric spectroscopy

    International Nuclear Information System (INIS)

    Results are presented for a non-contact measurement system capable of micron level spatial resolution. It utilises the novel electric potential sensor (EPS) technology, invented at Sussex, to image the electric field above a simple composite dielectric material. EP sensors may be regarded as analogous to a magnetometer and require no adjustments or offsets during either setup or use. The sample consists of a standard glass/epoxy FR4 circuit board, with linear defects machined into the surface by a PCB milling machine. The sample is excited with an a.c. signal over a range of frequencies from 10 kHz to 10 MHz, from the reverse side, by placing it on a conducting sheet connected to the source. The single sensor is raster scanned over the surface at a constant working distance, consistent with the spatial resolution, in order to build up an image of the electric field, with respect to the reference potential. The results demonstrate that both the surface defects and the internal dielectric variations within the composite may be imaged in this way, with good contrast being observed between the glass mat and the epoxy resin.

  20. Dielectric bow-tie nanocavity.

    Science.gov (United States)

    Lu, Qijing; Shu, Fang-Jie; Zou, Chang-Ling

    2013-12-15

    We propose a novel dielectric bow-tie (DBT) nanocavity consisting of two opposing tip-to-tip triangle semiconductor nanowires, whose end faces are coated by silver nanofilms. Based on the advantages of the dielectric slot and tip structures, and the high reflectivity of the silver mirror, light can be confined in this nanocavity with low loss. We demonstrate that at 4.5 K (300 K) around the resonance wavelength of 1550 nm, the mode excited in this nanocavity has a deep subwavelength mode volume of 2.8×10(-4) μm³ and a high quality factor of 4.9×10(4) (401.3), corresponding to an ultrahigh Purcell factor of 1.6×10(7) (1.36×10(5)). This DBT nanocavity may find applications for integrated nanophotonic circuits, such as high-efficiency single photon sources, thresholdless nanolasers, and strong coupling in cavity quantum electrodynamics experiments. PMID:24322245

  1. Loading system mechanism for dielectric elastomer generators with equi-biaxial state of deformation

    Science.gov (United States)

    Fontana, M.; Moretti, G.; Lenzo, B.; Vertechy, R.

    2014-03-01

    Dielectric Elastomer Generators (DEGs) are devices that employ a cyclically variable membrane capacitor to produce electricity from oscillating sources of mechanical energy. Capacitance variation is obtained thanks to the use of dielectric and conductive layers that can undergo different states of deformation including: uniform or non-uniform and uni- or multi-axial stretching. Among them, uniform equi-biaxial stretching is reputed as being the most effective state of deformation that maximizes the amount of energy that can be extracted in a cycle by a unit volume of Dielectric Elastomer (DE) material. This paper presents a DEG concept, with linear input motion and tunable impedance, that is based on a mechanical loading system for inducing uniform equi-biaxial states of deformation. The presented system employs two circular DE membrane capacitors that are arranged in an agonist-antagonist configuration. An analytical model of the overall system is developed and used to find the optimal design parameters that make it possible to tune the elastic response of the generator over the range of motion of interest. An apparatus is developed for the equi-biaxial testing of DE membranes and used for the experimental verification of the employed numerical models.

  2. Dielectric Track Detector fuel motion monitor system

    International Nuclear Information System (INIS)

    The fuel motion monitor system described is one of the systems being developed for use in the upgraded Sandia ACPR. Like the hodoscope, this system will image fast neutrons from the test fuel element--but there the similarity to the hodoscope ends, because this system will use Dielectric Track Detectors (DTD's) for both neutron detection and recording. Kimfoil is a commercial polycarbonate film that is used as a capacitor dielectric. It is just one example of a Dielectric Track Detector. When a DTD is struck by an energetic and heavy ion, the ion produces damage along its path. If the dielectric is then etched, the damaged track enlarges to form a crater. These craters are then easily visible with an optical microscope. These dielectrics have several properties that make them ideal for use in a reactor environment. First of all, they are completely insensitive to any of the background radiations to which they can be exposed in that environment

  3. Anticipating electrical breakdown in dielectric elastomer actuators

    Science.gov (United States)

    Muffoletto, Daniel P.; Burke, Kevin M.; Zirnheld, Jennifer L.

    2013-04-01

    The output strain of a dielectric elastomer actuator is directly proportional to the square of its applied electric field. However, since the likelihood of electric breakdown is elevated with an increased applied field, the maximum operating electric field of the dielectric elastomer is significantly derated in systems employing these actuators so that failure due to breakdown remains unlikely even as the material ages. In an effort to ascertain the dielectric strength so that stronger electric fields can be applied, partial discharge testing is used to assess the health of the actuator by detecting the charge that is released when localized instances of breakdown partially bridge the insulator. Pre-stretched and unstretched samples of VHB4910 tape were submerged in dielectric oil to remove external sources of partial discharges during testing, and the partial discharge patterns were recorded just before failure of the dielectric sample.

  4. Microwave Dielectric and Magnetic Properties of Co-Zn Ferrites

    Science.gov (United States)

    Lamani, A. R.; Jayanna, H. S.; Naveen, C. S.; Rajeeva, M. P.; Prasanna, G. D.

    2015-02-01

    The dielectric permittivity, loss tangent, in the frequency range 1MHz to 1.8 GHz and hysteresis loop parameters at room temperature were studied on a series of Zn substituted cobalt ferrites with general formula Co1-xZnx Fe2O4 where (x=0.0, 0.2, 0.4, 0.6, 1.0.). The experimental results indicate that the Zn substitution affects all these parameters. The observed dispersion in dielectric permittivity with frequency is in accordance with Maxwell-Wagner model. The high temperature sintering is used to synthesize these materials via solid state reaction route and these samples were characterized by X-ray diffractometer (XRD), vibrating sample magnetometer (VSM). The saturation magnetizations (MS) Hc and Mr of the Particles were measured at room temperature. Here for the smaller dopent concentration Ms increases with increasing in the Zn content this can explained on the basis of increased number of magnetic ions in the spinel lattice, at some point Ms decrease because of the difference between the magnetic moment of Fe2+ and Zn2+, the magnetic moment of the A sub lattice will increases and the moment of the B sub lattice will decrease. The variation of crystalline shape ellipsoid is correlated with variation of dielectric constant.

  5. Cavity Mode Frequencies and Large Optomechanical Coupling in Two-Membrane Cavity Optomechanics

    CERN Document Server

    Li, J; Malossi, N; Vitali, D

    2015-01-01

    We study the cavity mode frequencies of a Fabry-Perot cavity containing two vibrating dielectric membranes and the corresponding optomechanical coupling. Due to optical interference, extremely large optomechanical coupling of the membrane relative motion is achieved when the two membranes are placed very close to a resonance of the inner cavity formed by the two membranes, and in the limit of highly reflective membranes. The upper bound of the coupling strength is given by the optomechanical coupling associated with the much shorter inner cavity, consistently with the analysis of A. Xuereb et al., Phys. Rev. Lett. 109, 223601 (2012).

  6. Protein-Induced Modulation of Chloroplast Membrane Morphology

    OpenAIRE

    Machettira, Anu B.; Groß, Lucia E.; Tillmann, Bodo; Weis, Benjamin L.; Englich, Gisela; Sommer, Maik S.; Königer, Martina; Schleiff, Enrico

    2012-01-01

    Organelles are surrounded by membranes with a distinct lipid and protein composition. While it is well established that lipids affect protein functioning and vice versa, it has been only recently suggested that elevated membrane protein concentrations may affect the shape and organization of membranes. We therefore analyzed the effects of high chloroplast envelope protein concentrations on membrane structures using an in vivo approach with protoplasts. Transient expression of outer envelope p...

  7. Preparation of Polyvinylidene Fluoride (PVDF) Hollow Fiber Hemodialysis Membranes

    OpenAIRE

    Qinglei Zhang; Xiaolong Lu; Lihua Zhao

    2014-01-01

    In this study, the polyvinylidene fluoride (PVDF) hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS). The influences of PVDF membrane thickness and polyethylene glycol (PEG) content on membrane morphologies, pore size, mechanical and permeable performance were investigated. It was found that membrane thickness and PEG content affected both the structure and performance of hollow fiber membranes. The tensile strength and rejection of bovine serum a...

  8. Aluminum nanoparticle/acrylate copolymer nanocomposites for dielectric elastomers with high dielectric constants

    Science.gov (United States)

    Hu, Wei; Zhang, Suki N.; Niu, Xiaofan; Liu, Chao; Pei, Qibing

    2014-03-01

    Dielectric elastomers are useful for large-strain actuation and energy harvesting. Their application has been limited by their low dielectric constants and consequently high driving voltage. Various fillers with high dielectric constants have been incorporated into different elastomer systems to improve the actuation strain, force output and energy density of the compliant actuators and generators. However, agglomeration may happen in these nanocomposites, resulting in a decrease of dielectric strength, an increase of leakage current, and in many instances the degree of enhancement of the dielectric constant. In this work, we investigated aluminum nanoparticles as nanofillers for acrylate copolymers. This metallic nanoparticle was chosen because the availability of free electrons could potentially provide an infinite value of dielectric constant as opposed to dielectric materials including ferroelectric nanocrystals. Moreover, aluminum nanoparticles have a self-passivated oxide shell effectively preventing the formation of conductive path. The surfaces of the aluminum nanoparticles were functionalized with methacrylate groups to assist the uniform dispersion in organic solutions and additionally enable copolymerization with acrylate copolymer matrix during bulk polymerization, and thus to suppress large range drifting of the nanoparticles. The resulting Al nanoparticle-acrylate copolymer nanocomposites were found to exhibit higher dielectric constant and increased stiffness. The leakage current under high electric fields were significantly lower than nanocomposites synthesized without proper nanoparticle surface modification. The dielectric strengths of the composites were comparable with the pristine polymers. In dielectric actuation evaluation, the actuation force output and energy specific work density were enhanced in the nanocomposites compared to the pristine copolymer.

  9. Centrifugal membrane filtration - Task 9

    International Nuclear Information System (INIS)

    The Energy and Environmental Research Center (EERC) has teamed with SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, to demonstrate applications for the SpinTek technology within the US Department of Energy (DOE) Environmental management (EM) Program. The technology uses supported microporous membranes rotating at high rpm, under pressure, to separate suspended and colloidal solids from liquid streams, yielding a solids-free permeate stream and a highly concentrated solids stream. This is a crosscutting technology that falls under the Efficient Separations and Processing Crosscutting Program, with potential application to tank wastes, contaminated groundwater, landfill leachate, and secondary liquid waste streams from other remediation processes, including decontamination and decommissioning systems. Membrane-screening tests were performed with the SpinTek STC-X4 static test cell filtration unit, using five ceramic membranes with different pore size and composition. Based on permeate flux, a 0.25-microm TiO2/Al2O3 membrane was selected for detailed performance evaluation using the SpinTek ST-IIL centrifugal membrane filtration unit with a surrogate tank waste solution. An extended test run of 100 hr performed on a surrogate tank waste solution showed some deterioration in filtration performance, based on flux, apparently due to the buildup of solids near the inner portion of the membrane where relative membrane velocities were low. Continued testing of the system will focus on modifications to the shear pattern across the entire membrane surface to affect improved long-term performance

  10. Channeling of Protons Through Carbon Nanotubes Embedded in Dielectric Media

    OpenAIRE

    Borka, D.; Mowbray, D. J.; Mišković, Z. L.; Petrović, S.; Nešković, N.

    2008-01-01

    We investigate how the dynamic polarization of the carbon atoms valence electrons affects the spatial distributions of protons channeled in the (11, 9) single-wall carbon nanotubes placed in vacuum and embedded in various dielectric media. The initial proton speed is varied between 3 and 8 a.u., corresponding to the energies between 0.223 and 1.59 MeV, respectively, while the nanotube length is varied between 0.1 and 0.8 $\\mu$m. The spatial distributions of channeled protons are generated usi...

  11. Electromechanical deformation of conical dielectric elastomer actuator with hydrogel electrodes

    Science.gov (United States)

    Zhang, Chi; Sun, Wenjie; Chen, Hualing; Liu, Lei; Li, Bo; Li, Dichen

    2016-03-01

    A conical Dielectric Elastomer Actuator (DEA) undergoes large actuation strain in longitudinal direction when subject to a voltage across the membrane. The conical DEA is modeled using continuum mechanics and multilayered material thermodynamic theories which can consider not only the inhomogeneous deformation of the DEA but also the effect of elastomeric electrodes on the DEA. Hydrogels with lithium chloride electrolyte are synthesized and introduced as electrodes. The theory coincides well with the experimental results and succeeds in predicting the occurrence of loss of tension. At a low level of pre-stretch λp=2 , electric breakdown always occurs before the loss of tension, independent of shear modulus of hydrogels. When the pre-stretch increases to 4, the dominating failure mode changes from electric breakdown to loss of tension. At μGE L=6 kPa , loss of tension and electric breakdown almost happen simultaneously and the maximum actuation strain occurs at λp=4 .

  12. Dielectric Coatings for IACT Mirrors

    CERN Document Server

    Förster, A; Chadwick, P; Held, M

    2013-01-01

    Imaging Atmospheric Cherenkov Telescopes for very-high energy gamma-ray astronomy need mirror with high reflectance roughly in the wavelength between 300 and 550 nm. The current standard reflective layer of such mirrors is aluminum. Being permanently exposed to the environment they show a constant degradation over the years. New and improved dielectric coatings have been developed to enhance their resistance to environmental impact and to extend their possible lifetime. In addition, these customized coatings have an increased reflectance of over 95% and are designed to significantly lower the night-sky background contribution. The development of such coatings for mirrors with areas up to 2 m2 and low application temperatures to suite the composite materials used for the new mirror susbtrates of the Cherenkov Telescope Array (CTA) and the results of extensive durability tests are presented.

  13. Virtual gap dielectric wall accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Caporaso, George James; Chen, Yu-Jiuan; Nelson, Scott; Sullivan, Jim; Hawkins, Steven A

    2013-11-05

    A virtual, moving accelerating gap is formed along an insulating tube in a dielectric wall accelerator (DWA) by locally controlling the conductivity of the tube. Localized voltage concentration is thus achieved by sequential activation of a variable resistive tube or stalk down the axis of an inductive voltage adder, producing a "virtual" traveling wave along the tube. The tube conductivity can be controlled at a desired location, which can be moved at a desired rate, by light illumination, or by photoconductive switches, or by other means. As a result, an impressed voltage along the tube appears predominantly over a local region, the virtual gap. By making the length of the tube large in comparison to the virtual gap length, the effective gain of the accelerator can be made very large.

  14. Changes in the dielectric properties of medaka fish embryos during development, studied by electrorotation

    Energy Technology Data Exchange (ETDEWEB)

    Shirakashi, Ryo, E-mail: aa21150@iis.u-tokyo.ac.jp [Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505 (Japan); Mischke, Miriam [Lehrstuhl fuer Biotechnologie und Biophysik, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany); Fischer, Peter [Physiologische Chemie, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany); Memmel, Simon [Lehrstuhl fuer Biotechnologie und Biophysik, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany); Krohne, Georg [Abteilung fuer Elektronenmikroskopie, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany); Fuhr, Guenter R. [Lehrstuhl fuer Biotechnologie und Medizintechnik, Universitaet des Saarlandes, Saarbruecken (Germany); Zimmermann, Heiko [Lehrstuhl fuer Molekulare und Zellulaere Biotechnologie, Universitaet des Saarlandes, Saarbruecken (Germany); Sukhorukov, Vladimir L., E-mail: sukhorukov@biozentrum.uni-wuerzburg.de [Lehrstuhl fuer Biotechnologie und Biophysik, Biozentrum, Universitaet Wuerzburg, Wuerzburg (Germany)

    2012-11-09

    Highlights: Black-Right-Pointing-Pointer Electrorotation offers a non-invasive tool for dielectric analysis of fish embryos. Black-Right-Pointing-Pointer The three-shell dielectric model matches the rotation spectra of medaka eggs. Black-Right-Pointing-Pointer The capacitance value suggests a double-membrane structure of yolk envelope. -- Abstract: The Japanese medaka fish, Oryzias latipes, has become a powerful vertebrate model organism in developmental biology and genetics. The present study explores the dielectric properties of medaka embryos during pre-hatching development by means of the electrorotation (ROT) technique. Due to their layered structure, medaka eggs exhibited up to three ROT peaks in the kHz-MHz frequency range. During development from blastula to early somite stage, ROT spectra varied only slightly. But as the embryo progressed to the late-somite stage, the ROT peaks underwent significant changes in frequency and amplitude. Using morphological data obtained by light and electron microscopy, we analyzed the ROT spectra with a three-shell dielectric model that accounted for the major embryonic compartments. The analysis yielded a very high value for the ionic conductivity of the egg shell (chorion), which was confirmed by independent osmotic experiments. A relatively low capacitance of the yolk envelope was consistent with its double-membrane structure revealed by transmission electron microscopy. Yolk-free dead eggs exhibited only one co-field ROT peak, shifted markedly to lower frequencies with respect to the corresponding peak of live embryos. The dielectric data may be useful for monitoring the development and changes in fish embryos' viability/conditions in basic research and industrial aquaculture.

  15. Extending applications of dielectric elastomer artificial muscle

    Science.gov (United States)

    Chiba, Seiki; Waki, Mikio; Kornbluh, Roy; Pelrine, Ron

    2007-04-01

    Dielectric elastomers have demonstrated high energy density and high strains as well as high electromechanical efficiency and fast speeds of response. These properties, combined with their projected low cost make them attractive for a variety of actuator applications including linear actuators, diaphragm pumps, rotary motors, and haptic displays. Dielectric elastomers have also been shown to offer high energy density, high efficiency, and large strains when operated as generators. Dielectric elastomers have reached a stage of development where standardized products can be applied to new applications. In some cases, dielectric elastomer devices are improvements over existing devices. In other cases, however, dielectric elastomers can enable new types of devices that cannot be made with existing technologies, such as new types of loudspeakers and power generating devices. A new dipole loudspeaker system was developed using a commercially available push-pull diaphragm configuration. This same transducer configuration was used to develop a new power generating system. This generator system enables a power generation of 0.06 to 0.12 W by manually displacing the device by 5 to 6 mm once a second. By introducing a voltage step-down conversion circuit, the device was able to power wireless communications, allowing the control of devices separated by a distance of a few meters. These two devices are examples of the new applications that are enabled as the dielectric elastomer technology commercially emerges. Future improvements to dielectric elastomers could enable new capabilities in clean electrical power generation from ocean waves, for example.

  16. Dielectric investigation of some woven fabrics

    Science.gov (United States)

    Cerovic, Dragana D.; Dojcilovic, Jablan R.; Asanovic, Koviljka A.; Mihajlidi, Tatjana A.

    2009-10-01

    In this paper, we have investigated the temperature dependence of dielectric properties (relative dielectric permeabilities and dielectric tangents of losses) for woven fabrics of hemp, jute, flax, cotton, polyester (PES), cotton-PES mixture, and wool. The measurements have been carried out at a temperature range from -50 to 50 °C in the electric periodic field at a frequency 1 MHz in vacuum. For the same specimens, the values of the dielectric properties have also been measured at an air temperature of 21 °C and at relative humidities of 40%, 60%, and 80%. At different frequencies from 80 kHz to 5 MHz, the dielectric properties have been measured at a relative humidity of 40% and at a temperature of 21 °C. An investigation of the dielectric properties of woven fabrics can provide a better understanding of the relation between the dielectric properties of woven fabrics and the different raw material compositions, temperatures, relative air humidities, and frequencies for specimens. Hence, this investigation helps to improve textile material properties.

  17. Autonomous dielectric elastomer generator using electret

    Science.gov (United States)

    Vu-Cong, T.; Jean-Mistral, C.; Sylvestre, A.

    2013-04-01

    Dielectric elastomers can work as a variable capacitor to convert mechanical energy such as human motion into electrical energy. Nevertheless, scavengers based on dielectric elastomers require a high voltage source to polarize them, which constitutes the major disadvantage of these transducers. We propose here to combine dielectric elastomer with an electret, providing a quasi-permanent potential, thus replacing the high voltage supply. Our new scavenger is fully autonomous, soft, lightweight and low cost. Our structure is made of a dielectric elastomer (Polypower from Danfoss) and an electret developing a potential of -1000V (Teflon from Dupont). The transducer is designed specifically to scavenge energy from human motion. Thus, it works on pure-shear mode with maximum strain of about 50% and it is textured in 3D form because electret is not deformable. The shape of the hybrid structure is critical to insure huge capacitance variation and thus higher scavenged energy. We present in this paper our process for the optimization of the 3D shape that leads us to the developpment and characterization of our first prototype. From an appropriate electromechanical analytical model, an energy density of about 1.48mJ.g-1 is expected on an optimal electrical load. Our new autonomous dielectric generator can produce about 0.55mJ.g-1 on a resistive load, and can further be improved by enhancing the performance of dielectric elastomer such as dielectric permittivity or by increasing the electret potential.

  18. Dielectric resonances in disordered media

    Science.gov (United States)

    Raymond, L.; Laugier, J.-M.; Schäfer, S.; Albinet, G.

    2003-02-01

    Binary disordered systems are usually obtained by mixing two ingredients in variable proportions: conductor and insulator, or conductor and super-conductor. They present very specific properties, in particular the second-order percolation phase transition, with its fractal geometry and the multi-fractal properties of the current moments. These systems are naturally modeled by regular bi-dimensional or tri-dimensional lattices, on which sites or bonds are chosen randomly with given probabilities. The two significant parameters are the ratio h = σ1/σ of the complex conductances, σ and σ1, of the two components, and their relative abundances p (or, respectively, 1 - p). In this article, we calculate the impedance of the composite by two independent methods: the so-called spectral method, which diagonalises Kirchhoff's Laws via a Green function formalism, and the Exact Numerical Renormalization method (ENR). These methods are applied to mixtures of resistors and capacitors (R-C systems), simulating e.g. ionic conductor-insulator systems, and to composites constituted of resistive inductances and capacitors (LR-C systems), representing metal inclusions in a dielectric bulk. The frequency dependent impedances of the latter composites present very intricate structures in the vicinity of the percolation threshold. In this paper, we analyse the LR-C behavior of compounds formed by the inclusion of small conducting clusters (``n-legged animals'') in a dielectric medium. We investigate in particular their absorption spectra who present a pattern of sharp lines at very specific frequencies of the incident electromagnetic field, the goal being to identify the signature of each animal. This enables us to make suggestions of how to build compounds with specific absorption or transmission properties in a given frequency domain.

  19. How the antimicrobial peptides destroy bacteria cell membrane: Translocations vs. membrane buckling

    Science.gov (United States)

    Golubovic, Leonardo; Gao, Lianghui; Chen, Licui; Fang, Weihai

    2012-02-01

    In this study, coarse grained Dissipative Particle Dynamics simulation with implementation of electrostatic interactions is developed in constant pressure and surface tension ensemble to elucidate how the antimicrobial peptide molecules affect bilayer cell membrane structure and kill bacteria. We find that peptides with different chemical-physical properties exhibit different membrane obstructing mechanisms. Peptide molecules can destroy vital functions of the affected bacteria by translocating across their membranes via worm-holes, or by associating with membrane lipids to form hydrophilic cores trapped inside the hydrophobic domain of the membranes. In the latter scenario, the affected membranes are strongly corrugated (buckled) in accord with very recent experimental observations [G. E. Fantner et al., Nat. Nanotech., 5 (2010), pp. 280-285].

  20. Influences of acid-base property of membrane on interfacial interactions related with membrane fouling in a membrane bioreactor based on thermodynamic assessment.

    Science.gov (United States)

    Zhao, Leihong; Qu, Xiaolu; Zhang, Meijia; Lin, Hongjun; Zhou, Xiaoling; Liao, Bao-Qiang; Mei, Rongwu; Hong, Huachang

    2016-08-01

    Failure of membrane hydrophobicity in predicting membrane fouling requires a more reliable indicator. In this study, influences of membrane acid base (AB) property on interfacial interactions in two different interaction scenarios in a submerged membrane bioreactor (MBR) were studied according to thermodynamic approaches. It was found that both the polyvinylidene fluoride (PVDF) membrane and foulant samples in the MBR had relatively high electron donor (γ(-)) component and low electron acceptor (γ(+)) component. For both of interaction scenarios, AB interaction was the major component of the total interaction. The results showed that, the total interaction monotonically decreased with membrane γ(-), while was marginally affected by membrane γ(+), suggesting that γ(-) could act as a reliable indicator for membrane fouling prediction. This study suggested that membrane modification for fouling mitigation should orient to improving membrane surface γ(-) component rather than hydrophilicity. PMID:27155263

  1. Dielectric behaviour of strontium tartrate single crystals

    Indian Academy of Sciences (India)

    S K Arora; Vipul Patel; Brijesh Amin; Anjana Kothari

    2004-04-01

    Strontium tartrate trihydrate (STT) crystals have been grown in silica hydrogel. Various polarization mechanisms such as atomic polarization of lattice, orientational polarization of dipoles and space charge polarization in the grown crystals have been understood using results of the measurements of dielectric constant (') and dielectric loss (tan ) as functions of frequency and temperature. Ion core type polarization is seen in the temperature range 75–180°C, and above 180°C, there is interfacial polarization for relatively lower frequency range. One observes dielectric dispersion at lower frequency presumably due to domain wall relaxation.

  2. Development of dielectric-barrier-discharge ionization.

    Science.gov (United States)

    Guo, Cheng'an; Tang, Fei; Chen, Jin; Wang, Xiaohao; Zhang, Sichun; Zhang, Xinrong

    2015-03-01

    Dielectric-barrier-discharge ionization is an ambient-ionization technique. Since its first description in 2007, it has attracted much attention in such fields as biological analysis, food safety, mass-spectrometry imaging, forensic identification, and reaction monitoring for its advantages, e.g., low energy consumption, solvent-free method, and easy miniaturization. In this review a brief introduction to dielectric barrier discharge is provided, and then a detailed introduction to the dielectric-barrier-discharge-ionization technique is given, including instrumentation, applications, and mechanistic studies. Based on the summary of reported work, possible future uses of this type of ionization source are discussed at the end. PMID:25510973

  3. Microwave dielectric properties of nanostructured nickel ferrite

    Indian Academy of Sciences (India)

    John Jacob; M Abdul Khadar; Anil Lonappan; K T Mathew

    2008-11-01

    Nickel ferrite is one of the important ferrites used in microwave devices. In the present work, we have synthesized nanoparticles of nickel ferrite using chemical precipitation technique. The crystal structure and grain size of the particles are studied using XRD. The microwave dielectric properties of nanostructured nickel ferrite samples of three different average grain sizes and those of two sintered samples were studied. The parameters like dielectric constant, dielectric loss and heating coefficient of the nanoparticles samples are studied in the frequency range from 2.4 to 4 GHz. The values of these parameters are compared with those of sintered pellets of the same samples. All these parameters show size dependent variations.

  4. Dielectric/Ag/dielectric coated energy-efficient glass windows for warm climates

    Energy Technology Data Exchange (ETDEWEB)

    Durrani, S.M.A.; Khawaja, E.E. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Center for Applied Physical Sciences; Al Shukri, A.M.; Al Kuhaili, M.F. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Physics

    2004-09-01

    Energy-efficient glass windows for warm climates were designed and fabricated using a three-layer system of dielectric/metal/dielectric (D/M/D) on glass. Silver was used as a metal layer. The design parameters for optimum performance of D/M/D on glass-systems for dielectrics, having refractive indices in the range 1.6-2.4, were obtained by numerical calculations. Based on these parameters, D/M/D films on glass substrates were deposited using dielectrics such as TiO{sub 2}, WO{sub 3}, and ZnS. Upon testing these coated glass windows, it was concluded that the window with any of the three dielectrics performed well and the efficiencies of the windows with different dielectrics were nearly the same. [Author].

  5. The State of Water in Proton Conducting Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Allcock, Harry R.; Benesi, Alan; Macdonald, Digby D.

    2010-08-27

    The research carried out under grant No. DE-FG02-07ER46371, "The State of Water in Proton Conducting Membranes", during the period June 1, 2008 - May 31, 2010 was comprised of three related parts. These are: 1. An examination of the state of water in classical proton conduction membranes with the use of deuterium T1 NMR spectroscopy (Allcock and Benesi groups). 2. A dielectric relaxation examination of the behavior of water in classical ionomer membranes (Macdonald program). 3. Attempts to synthesize new proton-conduction polymers and membranes derived from the polyphosphazene system. (Allcock program) All three are closely related, crucial aspects of the design and development of new and improved polymer electrolyte fuel cell membranes on which the future of fuel cell technology for portable applications depends.

  6. Muscle-like high-stress dielectric elastomer actuators with oil capsules

    International Nuclear Information System (INIS)

    Despite being capable of generating large strains, dielectric elastomer actuators (DEAs) are short of strength. Often, they cannot produce enough stress or as much work as that achievable by human elbow muscles. Their maximum actuation capacity is limited by the electrical breakdown of dielectric elastomers. Often, failures of these soft actuators are pre-mature and localized at the weakest spot under high field and high stress. Localized breakdowns, such as electrical arcing, thermal runaway and punctures, could spread to ultimately cause rupture if they were not stopped. This work shows that dielectric oil immersion and self-clearable electrodes nibbed the buds of localized breakdowns from DEAs. Dielectric oil encapsulation in soft-membrane capsules was found to help the DEA sustain an ultra-high electrical breakdown field of 835 MVm−1, which is 46% higher than the electrical breakdown strength of the dry DEA in air at 570 MV m−1. Because of the increased apparent dielectric strength, this oil-capsuled DEA realizes a higher maximum isotonic work density of up to 31.51Jkg−1, which is 43.8% higher than that realized by the DEA in air. Meanwhile, it produces higher maximum isometric stress of up to 1.05 MPa, which is 75% higher than that produced by the DEA in air. Such improved actuator performances are comparable to those achieved by human flexor muscles, which can exert up to 1.2 MPa during elbow flexion. This muscle-like, high-stress dielectric elastomeric actuation is very promising to drive future human-like robots. (paper)

  7. Photothermal dielectric spectroscopy: A novel technique for the determination of the dielectric, pyroelectric and thermal properties of thin dielectric films

    OpenAIRE

    Wübbenhorst, Michael; van Turnhout, Jan

    1994-01-01

    A novel technique is described which combines dielectric measurements with a time and frequency dependent photothermal excitation. The sample, a thin metallized film, is placed in an aluminium ring which serves as a heat sink. At different temperatures both the dielectric and pyroelectric spectra are obtained by applying sequentially an AC-voltage and a modulated heat flux to the sample. The thermal properties are assessed by the application of a local laser heating; the resulting increase in...

  8. Nanoengineered membranes for controlled transport

    Science.gov (United States)

    Doktycz, Mitchel J [Oak Ridge, TN; Simpson, Michael L [Knoxville, TN; McKnight, Timothy E [Greenback, TN; Melechko, Anatoli V [Oak Ridge, TN; Lowndes, Douglas H [Knoxville, TN; Guillorn, Michael A [Knoxville, TN; Merkulov, Vladimir I [Oak Ridge, TN

    2010-01-05

    A nanoengineered membrane for controlling material transport (e.g., molecular transport) is disclosed. The membrane includes a substrate, a cover definining a material transport channel between the substrate and the cover, and a plurality of fibers positioned in the channel and connected to an extending away from a surface of the substrate. The fibers are aligned perpendicular to the surface of the substrate, and have a width of 100 nanometers or less. The diffusion limits for material transport are controlled by the separation of the fibers. In one embodiment, chemical derivitization of carbon fibers may be undertaken to further affect the diffusion limits or affect selective permeability or facilitated transport. For example, a coating can be applied to at least a portion of the fibers. In another embodiment, individually addressable carbon nanofibers can be integrated with the membrane to provide an electrical driving force for material transport.

  9. Omniphobic Membrane for Robust Membrane Distillation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, SH; Nejati, S; Boo, C; Hu, YX; Osuji, CO; Ehmelech, M

    2014-11-01

    In this work, we fabricate an omniphobic microporous membrane for membrane distillation (MD) by modifying a hydrophilic glass fiber membrane with silica nanoparticles followed by surface fluorination and polymer coating. The modified glass fiber membrane exhibits an anti-wetting property not only against water but also against low surface tension organic solvents that easily wet a hydrophobic polytetrafluoroethylene (PTFE) membrane that is commonly used in MD applications. By comparing the performance of the PTFE and omniphobic membranes in direct contact MD experiments in the presence of a surfactant (sodium dodecyl sulfate, SDS), we show that SDS wets the hydrophobic PTFE membrane but not the omniphobic membrane. Our results suggest that omniphobic membranes are critical for MD applications with feed waters containing surface active species, such as oil and gas produced water, to prevent membrane pore wetting.

  10. Development of a dielectric ceramic based on diatomite-titania part two: dielectric properties characterization

    OpenAIRE

    Medeiros Jamilson Pinto; Tavares Elcio Correia de Souza; Gomes Uilame Umbelino; Acchar Wilson

    1998-01-01

    Dielectric properties of sintered diatomite-titania ceramics are presented. Specific capacitance, dissipation factor, quality factor and dielectric constant were determined as a function of sintering temperature, titania content and frequency; the temperature coefficient of capacitance was measured as a function of frequency. Besides leakage current, the dependence of the insulation resistance and the dielectric strength on the applied dc voltage were studied. The results show that diatomite-...

  11. Reconstitution of the membrane protein OmpF into biomimetic block copolymer–phospholipid hybrid membranes

    Science.gov (United States)

    Bieligmeyer, Matthias; Artukovic, Franjo; Hirth, Thomas; Schiestel, Thomas

    2016-01-01

    Summary Structure and function of many transmembrane proteins are affected by their environment. In this respect, reconstitution of a membrane protein into a biomimetic polymer membrane can alter its function. To overcome this problem we used membranes formed by poly(1,4-isoprene-block-ethylene oxide) block copolymers blended with 1,2-diphytanoyl-sn-glycero-3-phosphocholine. By reconstituting the outer membrane protein OmpF from Escherichia coli into these membranes, we demonstrate functionality of this protein in biomimetic lipopolymer membranes, independent of the molecular weight of the block copolymers. At low voltages, the channel conductance of OmpF in 1 M KCl was around 2.3 nS. In line with these experiments, integration of OmpF was also revealed by impedance spectroscopy. Our results indicate that blending synthetic polymer membranes with phospholipids allows for the reconstitution of transmembrane proteins under preservation of protein function, independent of the membrane thickness. PMID:27547605

  12. Dielectric relaxation in dielectric mixtures: Application of the finite element method and its comparison with dielectric mixture formulas

    International Nuclear Information System (INIS)

    In this article, the frequency dependent dielectric properties, var-epsilon(ω), of an 'ideal binary composite structure were investigated by using the finite element method in the frequency domain. The material properties of the phases, i.e., dielectric permittivity, ε, and direct-current conductivity, σ, were assumed to be frequency independent. Moreover, the inclusion phase was more conductive than the matrix phase. The inclusions were infinitely long unidirectional cylinders which could be assumed to be hard disks in two dimensions in the direction perpendicular to the cylinder direction. Three different inclusion concentration levels were considered, e.g., low, intermediate, and high. The calculated dielectric relaxations were compared with those of the dielectric mixture formulas in the literature and it was found that there were no significant differences between the formulas and the numerical solutions at low inclusion concentration. Furthermore, the obtained responses were curve fitted by the addition of the Cole - Cole empirical expression and the ohmic losses by using a complex nonlinear least squares algorithm in order to explain the plausible physical origin of the Cole - Cole type dielectric relaxation. The dielectric relaxations were Debye-like when the concentration of the inclusions were low. For intermediate and high concentrations, the responses obtained from the numerical simulations deviated from that of the Debye one, whose curve fittings with the Cole - Cole empirical expression were inadequate. [copyright] 2001 American Institute of Physics

  13. Identification of Structural Relaxation in the Dielectric Response of Water

    Science.gov (United States)

    Hansen, Jesper S.; Kisliuk, Alexander; Sokolov, Alexei P.; Gainaru, Catalin

    2016-06-01

    One century ago pioneering dielectric results obtained for water and n -alcohols triggered the advent of molecular rotation diffusion theory considered by Debye to describe the primary dielectric absorption in these liquids. Comparing dielectric, viscoelastic, and light scattering results, we unambiguously demonstrate that the structural relaxation appears only as a high-frequency shoulder in the dielectric spectra of water. In contrast, the main dielectric peak is related to a supramolecular structure, analogous to the Debye-like peak observed in monoalcohols.

  14. Effect of Dielectric Properties of a Solvent-Water Mixture Used in Microwave-Assisted Extraction of Antioxidants from Potato Peels

    Directory of Open Access Journals (Sweden)

    Ashutosh Singh

    2014-02-01

    Full Text Available The dielectric properties of a methanol-water mixture were measured at different temperatures from 20 to 80 °C at two frequencies 915 MHz and 2450 MHz. These frequencies are most commonly used on industrial and domestic scales respectively. In this study, the dielectric properties of a methanol-water mixture were found to be dependent on temperature, solvent concentration, and presence of plant matrix. Linear and quadratic equations were developed to establish the dependency between factors. At 2450 MHz, the dielectric constant of methanol-water mixtures was significantly affected by concentration of methanol rather than by temperature, whereas the dielectric loss factor was significantly affected by temperature rather than by methanol concentration. Introduction of potato peel led to an increase in the effect of temperature on the dielectric properties of the methanol fractions. At 915 MHz, both the dielectric properties were significantly affected by the increase in temperature and solvent concentration, while the presence of potato peel had no significant effect on the dielectric properties. Statistical analysis of the dissipation factor at 915 and 2450 MHz revealed that both temperature and solvent concentration had a significant effect on it, whereas introduction of potato peels at 915 MHz reduced the effect of temperature as compared to 2450 MHz. The total phenolic yield of the microwave-assisted extraction process was significantly affected by the solvent concentration, the dissipation factor of the methanol-water mixture and the extraction time.

  15. Effect of Dielectric Properties of a Solvent-Water Mixture Used in Microwave-Assisted Extraction of Antioxidants from Potato Peels.

    Science.gov (United States)

    Singh, Ashutosh; Nair, Gopu Raveendran; Liplap, Pansa; Gariepy, Yvan; Orsat, Valerie; Raghavan, Vijaya

    2014-01-01

    The dielectric properties of a methanol-water mixture were measured at different temperatures from 20 to 80 °C at two frequencies 915 MHz and 2450 MHz. These frequencies are most commonly used on industrial and domestic scales respectively. In this study, the dielectric properties of a methanol-water mixture were found to be dependent on temperature, solvent concentration, and presence of plant matrix. Linear and quadratic equations were developed to establish the dependency between factors. At 2450 MHz, the dielectric constant of methanol-water mixtures was significantly affected by concentration of methanol rather than by temperature, whereas the dielectric loss factor was significantly affected by temperature rather than by methanol concentration. Introduction of potato peel led to an increase in the effect of temperature on the dielectric properties of the methanol fractions. At 915 MHz, both the dielectric properties were significantly affected by the increase in temperature and solvent concentration, while the presence of potato peel had no significant effect on the dielectric properties. Statistical analysis of the dissipation factor at 915 and 2450 MHz revealed that both temperature and solvent concentration had a significant effect on it, whereas introduction of potato peels at 915 MHz reduced the effect of temperature as compared to 2450 MHz. The total phenolic yield of the microwave-assisted extraction process was significantly affected by the solvent concentration, the dissipation factor of the methanol-water mixture and the extraction time. PMID:26784666

  16. Dielectric properties of piezoelectric 3–0 composites of lithium ferrite/barium titanate

    Indian Academy of Sciences (India)

    P Sarah; S V Suryanarayana

    2003-12-01

    Piezoelectric 3–0 composite ceramics are prepared from a mixture of barium titanate and lithium ferrite phase constituents. Dielectric properties of composites are affected by a number of parameters that include electrical properties, size, shape and amount of constituent phases. The frequency dependent measurements can provide additional insight into mechanisms controlling electrical response. Frequency dependence of dielectric constant plots of lithium ferrite/barium titanate composites will be given and the relevance of trends seen in them will be discussed. Connectivity in composites developed is studied.

  17. All-dielectric subwavelength metasurface focusing lens.

    Science.gov (United States)

    West, Paul R; Stewart, James L; Kildishev, Alexander V; Shalaev, Vladimir M; Shkunov, Vladimir V; Strohkendl, Friedrich; Zakharenkov, Yuri A; Dodds, Robert K; Byren, Robert

    2014-10-20

    We have proposed, designed, manufactured and tested low loss dielectric micro-lenses for infrared (IR) radiation based on a dielectric metamaterial layer. This metamaterial layer was created by patterning a dielectric surface and etching to sub-micron depths. For a proof-of-concept lens demonstration, we have chosen a fine patterned array of nano-pillars with variable diameters. Gradient index (GRIN) properties were achieved by engineering the nano-pattern characteristics across the lens, so that the effective optical density of the dielectric metamaterial layer peaks around the lens center, and gradually drops at the lens periphery. A set of lens designs with reduced reflection and tailorable phase gradients have been developed and tested, demonstrating focal distances of a few hundred microns, beam area contraction ratio up to three, and insertion losses as low as 11%. PMID:25401653

  18. Casimir Torque in Inhomogeneous Dielectric Plates

    CERN Document Server

    Long, William

    2013-01-01

    In this work, we consider a torque caused by the well known quantum mechanical Casimir effect arising from quantized field fluctuations between plates with inhomogeneous, sharply discontinuous, dielectric properties. While the Casimir effect is a relatively well understood phenomenon, systems resulting in lateral or rotational forces are far less developed; to our knowledge, a theoretical study of discontinuous dielectric variants of such systems has not been attempted. We utilize a Proximity Force Approximation in conjunction with the Lifshitz dielectric formula to perform theoretical analyses of resultant torques in systems with bisected and quadrisected dielectric regions. We also develop a high precision Monte Carlo type numerical integrator to approximate our derived expressions. Our calculations of an energy density linear with the alignment angle result in a constant torque and have implications in NEMS (nano electromechanical systems) and MEMS (micro electromechanical systems), including a postulated ...

  19. High Gradient Wakefields in Dielectric Loaded Structures

    International Nuclear Information System (INIS)

    Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short electron bunches of up to 86 nC are used to drive these fields, either as single bunches or as bunch trains. The structures consist of cylindrical ceramic tubes (cordierite) with a dielectric constant of 4.76, inserted into cylindrical copper waveguides. These standing-wave structures have a field probe near the outer diameter of the dielectric, in order to sample the RF fields generated by the electron bunches. Monitoring the field probe signal serves to verify the absence of electric breakdown in the structures. MAFIA simulations are used to calculate the amplitude of the fields generated by the traversing electrons bunches

  20. Multipactor experiment on a dielectric surface

    International Nuclear Information System (INIS)

    A novel experiment to investigate single-surface multipactor on a dielectric surface was developed and tested. The compact apparatus consists of a small brass microwave cavity in a high vacuum system. The cavity is ∼15 cm in length with an outer diameter of ∼10 cm. A pulsed variable frequency microwave source at ∼2.4 GHz, 2 kW peak excites the TE111 mode with a strong electric field parallel to a dielectric plate (∼0.2 cm thickness) that is inserted at midlength of the cavity. The microwave pulses are monitored by calibrated microwave diodes. An electron probe measures electron current and provides temporal measurements of the multipactor electron current with respect to the microwave pulses. Phosphor on the dielectric surface is used to detect multipactor electrons by photoemission. The motivation of this experiment is to test recent theoretical calculations of single-surface multipactor on a dielectric

  1. Dielectric films improve life of polymeric insulators

    Science.gov (United States)

    Hudis, M.; Wydeven, T.

    1975-01-01

    Degradation of polymeric insulators may be significantly reduced when polymer surfaces are coated with film having gradation of dielectric constants, larger where it is in contact with polymer and smaller at its exposed surface.

  2. A study of microcalorimeter with dielectric thermometer

    International Nuclear Information System (INIS)

    The microcalorimeter detects a single particle of radiation by means of the temperature rise in the absorber kept at low temperature below 1 K. A sensitive thermometer measuring the temperature rise is an important component in the microcalorimeter. Dielectric materials whose electric capacitances depend on temperature at low temperature can be utilized for the sensitive thermometer of the microcalorimeter. The temperature dependence of the electric capacitance d(ln Cd)/dT is an important parameter for the dielectric thermometer. We have studied the dielectric thermometer made of SrTiO3 based material and carried out measurement of the electric capacitance in the temperature range from 50 mK to 120 mK. By using experimental values of d(ln Cd)/dT an output signal of the dielectric microcalorimeter was estimated in the detection of a 5.5 MeV α-particle. (author)

  3. Ferroelectric and dielectric properties of electroactive oligomers and nanocomposites

    Science.gov (United States)

    Kraemer, Kristin L.

    repeatability from sample to sample. The final study was on the effect of humidity in poly(vinylidene fluoride- trifluoroethylene) 70:30. Water vapor could enter the film, reside in the lattice, and affect the dielectric measurements. Based on dielectric measurements, the amount of water in the film at 80% relative humidity was 0.046%. With 50 nm aluminum electrodes, the vapor entered the film quickly, although it took five to six hours to leave at room temperature.

  4. Polariton spectrum in nonlinear dielectric medium

    OpenAIRE

    Dzedolik, Igor V.; Karakchieva, O.

    2012-01-01

    We obtain theoretically the phonon-polariton spectrum in nonlinear dielectric medium with the third order Kerr-type nonlinearity. We investigate the dependence of number of the polariton spectrum branches on the intensity of electromagnetic field and demonstrate that the appearance of new branches located in the polariton spectrum gap is caused by the influence of dispersion of the third order dielectric susceptibility at intensity field in the medium. The modulation instability of new branch...

  5. Polariton waves in nonlinear dielectric medium

    OpenAIRE

    Dzedolik, I. V.; Karakchieva, O. S.

    2012-01-01

    The phonon-polariton spectrum in dielectric medium with the third order nonlinearity was theoretically obtained. Dependence of number of polariton spectrum branches on intensity of electromagnetic field was investigated. The appearance of new branches located in the polariton spectrum gap was caused by the influence of dispersion of the third order dielectric susceptibility at increment of the field intensity in the medium. The soliton and cnoidal wave solutions for the polariton excitations ...

  6. PREFACE: Dielectrics 2009: Measurement Analysis and Applications

    Science.gov (United States)

    Vaughan, Alun; Williams, Graham

    2009-07-01

    The conference Dielectrics 2009: Measurements, Analysis and Applications represents a significant milestone in the evolution of dielectrics research in the UK. It is reasonable to state that the academic study of dielectrics has led to many fundamental advances and that dielectric materials underpin the modern world in devices ranging from field effect transistors, which operate at extremely high fields, albeit low voltages, to the high voltage plants that provide the energy that powers our economy. The origins of the Dielectrics Group of the Institute of Physics (IOP), which organized this conference, can be traced directly back to the early 1960s, when Professor Mansel Davies was conducting research into the dielectric relaxation behaviour of polar liquids and solids at The Edward Davies Chemical Laboratories of the University College of Wales, Aberystwyth. He was already well-known internationally for his studies of molecular structure and bonding of small molecules, using infra-red-spectroscopy, and of the physical properties of hydrogen-bonded liquids and solids, using thermodynamic methods. Dielectric spectroscopy was a fairly new area for him and he realized that opportunities for scientists in the UK to gather together and discuss their research in this developing area of physical chemistry/chemical physics were very limited. He conceived the idea of forming a Dielectrics Discussion Group (DDG), which would act as a meeting point and provide a platform for dielectrics research in the UK and beyond and, as a result, a two-day Meeting was convened in the spring of 1968 at Gregynog Hall of the University of Wales, near Newtown, Montgomeryshire. It was organized by Mansel Davies, Alun Price and Graham Williams, all physical chemists from the UCW, Aberystwyth. Fifty scientists attended, being a mix of physical chemists, theoretical chemists, physicists, electrical engineers, polymer and materials scientists, all from the UK, except Dr Brendan Scaife of Trinity

  7. Dielectric properties of Jordanian oil shales

    Energy Technology Data Exchange (ETDEWEB)

    Al-Harahsheh, Mohammad; Alnawafleh, Hani [Department of Mining Engineering, College of Mining and Environmental Engineering, Al-Hussein Bin Talal University, Ma' an 20 (Jordan); Kingman, Sam; Saeid, Abdurrahman; Robinson, John; Dimitrakis, Georgios [Process and Environmental Research Division Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD (United Kingdom)

    2009-10-15

    Microwave heating has been suggested by various authors as a suitable technology for extraction of organic material from oil shales. However, one of the limiting factors in the development of this technology is a lack of accurate dielectric property data for design purposes. In this study the dielectric behaviour of El-lajun oil shale is quantified. The dielectric constant and loss factor of El-lajun oil shale were measured at 2470 and 912 MHz using the cavity perturbation technique. The effects of organic content, temperature, and moisture content on the microwave heating efficiency were quantified. Coaxial probe technique was also employed to study the effect of frequency on dielectric properties of oil shale. Generally, it was found that all samples were of low dielectric loss at room temperature with the imaginary part of permittivity falling significantly after the moisture was removed. This suggests that the major contribution in the dielectric loss is due to the presence of free and/or interlayer water. It was found that both the real and imaginary part of complex permittivity increased with a rise in temperature from 20 up to 80 C, then dropped significantly at about 100 C before staying approximately constant up to a temperature of about 480 C. From this temperature both the real and imaginary parts of complex permittivity increased sharply with further increase in temperature. An attempt was also made to correlate the dielectric properties of the bulk shale sample with the organic content. However, no correlation between dielectric properties and organic matter content was found. (author)

  8. Dielectric Behavior of Middle Phase Microemulsion

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Dielectric measurements were performed on middle phase microemulsions composed of sodium dodecylsulfate(SDS), cetyltrimethylammonium bromide(CTAB), n-butanol, n-heptane and brine. Distinct and unique dielectric behavior, with characteristic frequency dependence regularity on the salinity of the microemulsions, was observed in the low-frequency range from 10-103Hz. It can be considered to be an interfacial polarization mechanism.

  9. Dielectric silicone elastomers with mixed ceramic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Stiubianu, George, E-mail: george.stiubianu@icmpp.ro [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Bele, Adrian; Cazacu, Maria; Racles, Carmen; Vlad, Stelian [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Ignat, Mircea [National R& D Institute for Electrical Engineering ICPE-CA Bucharest, Splaiul Unirii 313, District 3, Bucharest 030138 (Romania)

    2015-11-15

    Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles.

  10. Pulsed corona and dielectric-barrier discharge processing of trichloroethylene

    Energy Technology Data Exchange (ETDEWEB)

    Hsiao, M.C.; Merritt, B.T.; Penetrante, B.M.; Vogtlin, G.E.; Wallman, P.H. [Lawrence Livermore National Lab., CA (United States)

    1995-12-31

    This paper presents experimental results on the plasma assisted decomposition of dilute concentrations (100--200 ppm) of trichloroethylene (TCE) in atmospheric-pressure dry air streams by pulsed corona and dielectric-barrier discharge processing. The experiments were performed at gas temperatures up to 300 A1C. One of the objectives in these experiments is to study the effect of gas temperature on the removal chemistry and product formation. The data on the gas temperature dependence provide a good basis for elucidating the chemical kinetics of TCE decomposition in the plasma. Under identical gas conditions the type of electrical discharge reactor does not affect the electrical energy requirements for decomposing the same amount of TCE; the reactor type also does not affect the product formation. For input energy densities up to 300 Joules per liter, the authors observe that carbon monoxide (CO) and carbon dioxide (CO2) are only minor products in the decomposition of TCE. The main organic products are phosgene and dichloroacetyl chloride (DCAC), as inferred from the Fourier Transform Infrared (FTIR) spectra. Processing at higher gas temperatures (around 300 A1C) increases the electrical energy required to remove the same amount of TCE; however, the CO and CO2 yields increase substantially and higher amounts of hydrochloric acid (HCl) are formed. These trends suggest increased competition from decomposition of DCAC and/or phosgene at high temperatures. In all cases, pulsed corona or dielectric-barrier discharge processing produces CO preferentially over CO2.

  11. Dielectric constant/ loss behaviour of high energy 238U ion irradiated polymer liquid crystal

    International Nuclear Information System (INIS)

    Dielectric constant/loss behaviour in high energy 238U (11.6 MeV/n) ion irradiated poly (P-hydroxy benzoic acid-co-ethylene terephthalate) PET/ x.PHB (x is the molar concentration) has been investigated. The observations were made at temperature ranging from 20 to 250 degC at the frequencies 120Hz, 1kHz, 10kHz and 100kHz by using Keithley precession LCZ meter. PET rich phase has been affected drastically by high energy heavy ion irradiation as the dielectric constant is suppressed in contrast to sharp increase in dielectric constant between 40 to 100 degC in pristine PET. The appearance of few kinks in the low temperature region due to decomposition of carboxyl group is evident in high energy heavy ion irradiated 0.7 PHB. (author)

  12. Three-dimensional theory of Smith-Purcell free-electron laser with dielectric loaded grating

    International Nuclear Information System (INIS)

    A dielectric loaded rectangular grating for Smith-Purcell devices is proposed in this paper. Regarding the electron beam as a moving plasma dielectric, a three dimensional (3D) linear theory of beam-wave interaction is developed. The first and second order growth rates are calculated, which are obtained by expanding hot dispersion equation at synchronous point. The results show that the cutoff frequency is affected by grating width. The dispersion curve becomes flatter and shifts towards lower frequency by loading dielectric in grooves. The simulation results, which are obtained by a 3D particle-in-cell code, are in good agreement with theoretical calculations. Compared the first and second order growth rate, it shows that the discrepancy is large when beam parameters are selected with high values. In this case, it is necessary to apply the second order growth rate, which can accurately describe the process of beam-wave interaction.

  13. Silicon carbide powders: Temperature-dependent dielectric properties and enhanced microwave absorption at gigahertz range

    Science.gov (United States)

    Yang, Hui-Jing; Yuan, Jie; Li, Yong; Hou, Zhi-Ling; Jin, Hai-Bo; Fang, Xiao-Yong; Cao, Mao-Sheng

    2013-06-01

    The dielectric properties of SiC powders are investigated in the temperature range of 373-773 K at gigahertz range (8.2-12.4 GHz). The complex permittivity ɛ and the loss tgδ exhibit frequency-dependent characteristics with the frequency, and they also show temperature-dependent characteristic with the temperature. From the Cole-Cole plots, the relaxation and electrical conductance both affect the dielectric properties at high temperature. First principle calculations are employed to analyze the electronic structure of SiC, which infer the influence of relaxation and conductance on dielectric behaviors. The reflection loss RL peak is below -10 dB in temperatures of 373-773 K with the sample in thickness 2.1 mm. More importantly, the microwave absorption coupled with widening effective absorption bandwidth demonstrates positive temperature effects on the absorption with the increasing temperature, indicating promising potential applications in high-temperature microwave absorption fields.

  14. Dielectric properties of solution-grown-undoped and acrylic-acid-doped ethyl cellulose

    Indian Academy of Sciences (India)

    P K Khare; Sandeep K Jain

    2000-02-01

    Dielectric capacities and losses were measured, in the temperature (50–170°C) and frequency (01–100 kHz range), for undoped and acrylic acid (AA) doped ethyl cellulose (EC) films (thickness about 20 m) with progressive increase in the concentration of dopant in the polymer matrix. The variation of capacity with temperature is attributed to thermal expansion in the lower temperature region to the orientation of dipolar molecules in the neighbourhood of glass transition temperature () and random thermal motion of molecules above . The dielectric losses exhibit a broad peak. Doping with AA is found to affect the magnitude and position of the peak. AA is found to have a two-fold action. Firstly, it enhances the chain mobility and secondly, it increases the dielectric loss by forming charge transfer complexes.

  15. Preparation of Polyvinylidene Fluoride (PVDF Hollow Fiber Hemodialysis Membranes

    Directory of Open Access Journals (Sweden)

    Qinglei Zhang

    2014-02-01

    Full Text Available In this study, the polyvinylidene fluoride (PVDF hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS. The influences of PVDF membrane thickness and polyethylene glycol (PEG content on membrane morphologies, pore size, mechanical and permeable performance were investigated. It was found that membrane thickness and PEG content affected both the structure and performance of hollow fiber membranes. The tensile strength and rejection of bovine serum albumin (BSA increased with increasing membrane thickness, while the Ultrafiltration flux (UF flux of pure water was the opposite. The tensile strength, porosity and rejection of BSA increased with increasing PEG content within a certain range. Compared with commercial F60S membrane, the PVDF hollow fiber membrane showed higher mechanical and permeable performance. It was proven that PVDF material had better hydrophilicity and lower BSA adsorption, which was more suitable for hemodialysis. All the results indicate that PVDF hollow fiber membrane is promising as a hemodialysis membrane.

  16. Preparation of Polyvinylidene Fluoride (PVDF) Hollow Fiber Hemodialysis Membranes.

    Science.gov (United States)

    Zhang, Qinglei; Lu, Xiaolong; Zhao, Lihua

    2014-01-01

    In this study, the polyvinylidene fluoride (PVDF) hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS). The influences of PVDF membrane thickness and polyethylene glycol (PEG) content on membrane morphologies, pore size, mechanical and permeable performance were investigated. It was found that membrane thickness and PEG content affected both the structure and performance of hollow fiber membranes. The tensile strength and rejection of bovine serum albumin (BSA) increased with increasing membrane thickness, while the Ultrafiltration flux (UF) flux of pure water was the opposite. The tensile strength, porosity and rejection of BSA increased with increasing PEG content within a certain range. Compared with commercial F60S membrane, the PVDF hollow fiber membrane showed higher mechanical and permeable performance. It was proven that PVDF material had better hydrophilicity and lower BSA adsorption, which was more suitable for hemodialysis. All the results indicate that PVDF hollow fiber membrane is promising as a hemodialysis membrane. PMID:24957122

  17. Membranes for energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Peinemann, K.V.; Pereira Nunes, S. (eds.) [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    2008-07-01

    This volume contains the following chapters: 1. Sulfonated poly(arylether)-type polymers as proton exchange membranes: Synthesis and performance; 2. Polyimide ionomer membranes for PEFCs and DMFCs; 3. Membranes for high temperature PEFC based on acid-doped polybenzimidazoles; 4. Membrane for medium temperature PEFC based on Nafion filled with layered metal phosphates and phosphonates 5. Composite membranes for high temperature direct methanol fuel cells; 6. Dense ceramic membranes for hydrogen separation; 7. Membranes in energy systems with CO{sub 2} capture 8. Palladium membranes for hydrogen separation; 9. Membranes for power generation by pressure retarded osmosis.

  18. Electrophysiology of mycoplasma membranes.

    OpenAIRE

    Schummer, U.; Schiefer, H G

    1983-01-01

    The influence of transmembrane ion fluxes on mycoplasma membrane potentials was studied. Fluorescence intensity of potential-sensitive carbocyanine dyes was calibrated vs. electric membrane potential. Potassium and sodium ion diffusion potentials significantly contributed to mycoplasma membrane potential. Chloride ions were obviously freely permeable across mycoplasma membranes. Under growth conditions the mycoplasma membrane potential was estimated to be delta psi = - 80 mV.

  19. Electrical properties and dielectric spectroscopy of Ar{sup +} implanted polycarbonate

    Energy Technology Data Exchange (ETDEWEB)

    Chawla, Mahak, E-mail: mahak.chawla@gmail.com; Shekhawat, Nidhi; Aggarwal, Sanjeev; Sharma, Annu [Department of Physics, Kurukshetra University, Kurukshetra - 136119 (India); Nair, K. G. M. [Consultant, UGC-DAE Consortium for Scientific Research, Kalpakkam Node, Kokilamedu-603104, Tamilnadu (India)

    2015-05-15

    The aim of the present paper is to study the effect of argon ion implantation on electrical and dielectric properties of polycarbonate. Specimens were implanted with 130 keV Ar{sup +} ions in the fluence ranging from 1×10{sup 14} to 1×10{sup 16} ions cm{sup −2}. The beam current used was ∼0.40 µA cm{sup −2}. The electrical conduction behaviour of virgin and Ar{sup +} implanted polycarbonate specimens have been studied through current-voltage (I-V characteristic) measurements. It has been observed that after implantation conductivity increases with increasing ion fluence. The dielectric spectroscopy of these specimens has been done in the frequency range of 100 kHz-100 MHz. Relaxation processes were studied by Cole-Cole plot of complex permittivity (real part of complex permittivity, ε′ vs. imaginary part of complex permittivity, ε″). The Cole-Cole plots have also been used to determine static dielectric constant (ε{sub s}), optical dielectric constant (ε{sub ∞}), spreading factor (α), average relaxation time (τ{sub 0}) and molecular relaxation time (τ). The dielectric behaviour has been found to be significantly affected due to Ar{sup +} implantation. The possible correlation between this behaviour and the changes induced by the implantation has been discussed.

  20. Numerical simulation of the leaky dielectric microdroplet generation in electric fields

    Science.gov (United States)

    Kamali, Reza; Manshadi, Mohammad Karim Dehghan

    2016-07-01

    Microdroplet generation has a vast range of applications in the chemical, biomedical, and biological sciences. Several devices are applied to produce microdroplets, such as Co-flow, T-junction and Flow-focusing. The important point in the producing process is controlling the separated fluid volume in these devices. On the other hand, a large number of liquids, especially aqueous one, are influenced by electric or magnetic fields. As a consequence, an electric field could be used in order to affect the separated fluid volume. In this study, effects of an electric field on the microdroplet generation in a Co-flow device are investigated numerically. Furthermore, effects of some electrical properties such as permittivity on the separating process of microdroplets are studied. Leaky dielectric and perfect dielectric models are used in this investigation. According to the results, in the microdroplet generating process, leaky dielectric fluids show different behaviors, when an electric field is applied to the device. In other words, in a constant electric field strength, the volume of generated microdroplets can increase or decrease, in comparison with the condition without the electric field. However, for perfect dielectric fluids, droplet volume always decreases with increasing the electric field strength. In order to validate the numerical method of this study, deformation of a leaky dielectric droplet in an electric field is investigated. Results are compared with Taylor theoretical model.

  1. A detailed dielectric relaxation spectroscopy study of artificial UV weathered low density polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Ramanujam, Maalolan, E-mail: maalolan.ramanujam@bam.de [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany); Wachtendorf, Volker; Purohit, Purv J.; Mix, Renate; Schoenhals, Andreas; Friedrich, Joerg F. [BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin (Germany)

    2012-02-20

    Graphical abstract: - Abstract: Artificial weathering of LDPE under dry conditions (<10% of relative humidity) by UV radiation was monitored by dielectric spectroscopy. For an apolar polymer like LDPE, dielectric study yields information about the change in structure and dynamics of the system. The fluctuations of the polar groups which are generated as a result of photooxidation such as carbonyl groups can be monitored as characteristic relaxation processes like the {alpha}{sub c} or {beta} mode. The dielectric loss characterized by typical dielectric parameters like the activation energy and dielectric strength are strongly dependent upon changes induced by photooxidation in the amorphous and crystalline domains. This paper discusses in detail how the foil reached its mechanical disintegration. It was found that initial stages of weathering induce chain scission and/or crosslinking in the amorphous domains of the polymer and the motional processes in the crystalline regions are not affected. After this induction period, an increase in the degree of crystallization was observed by employing differential calorimetry. The increasing crystallinity is considered as one of the reasons for embrittlement which finally leads to the complete loss of the structural integrity.

  2. Polyunsaturated Lipids Regulate Membrane Domain Stability by Tuning Membrane Order.

    Science.gov (United States)

    Levental, Kandice R; Lorent, Joseph H; Lin, Xubo; Skinkle, Allison D; Surma, Michal A; Stockenbojer, Emily A; Gorfe, Alemayehu A; Levental, Ilya

    2016-04-26

    The plasma membrane (PM) serves as the functional interface between a cell and its environment, hosting extracellular signal transduction and nutrient transport among a variety of other processes. To support this extensive functionality, PMs are organized into lateral domains, including ordered, lipid-driven assemblies termed lipid rafts. Although the general requirements for ordered domain formation are well established, how these domains are regulated by cell-endogenous mechanisms or exogenous perturbations has not been widely addressed. In this context, an intriguing possibility is that dietary fats can incorporate into membrane lipids to regulate the properties and physiology of raft domains. Here, we investigate the effects of polyunsaturated fats on the organization of membrane domains across a spectrum of membrane models, including computer simulations, synthetic lipid membranes, and intact PMs isolated from mammalian cells. We observe that the ω-3 polyunsaturated fatty acid docosahexaenoic acid is robustly incorporated into membrane lipids, and this incorporation leads to significant remodeling of the PM lipidome. Across model systems, docosahexaenoic acid-containing lipids enhance the stability of ordered raft domains by increasing the order difference between them and coexisting nonraft domains. The relationship between interdomain order disparity and the stability of phase separation holds for a spectrum of different perturbations, including manipulation of cholesterol levels and high concentrations of exogenous amphiphiles, suggesting it as a general feature of the organization of biological membranes. These results demonstrate that polyunsaturated fats affect the composition and organization of biological membranes, suggesting a potential mechanism for the extensive effects of dietary fat on health and disease. PMID:27119640

  3. Dolichol alters brain membrane functions

    International Nuclear Information System (INIS)

    It has been well demonstrated that there is a direct correlation between increase in dolichol level in brain and aging. An abnormally high level of dolichol was found in brain tissue of patients with pathological aging disorders. The aim of this study is to examine the physiological significance of dolichol affecting membrane transport activity and phospholipid acyl group turnover. Dolichol added to synaptic plasma membranes resulted in a biphasic effect on (Na+, K+)-ATPase, i.e., an enhancement of activity at low concentrations (5 μg/125 mg protein) and an inhibition of activity at high concentrations (40-100 μg). To probe the membrane acyl group turnover, the incorporation of [14C]-arachidonate into plasma membrane phospholipids was examined in the presence and absence of dolichol. Dolichol elicited an increase in the incorporation of label into phospholipids. However, the effects varied depending on whether BSA is present. In the absence of BSA, the increase in labeling of phosphatidylinositols is higher than that of phosphatidylcholines. These results suggest that dolichols, when inserted into membranes, may alter membrane functions

  4. Dolichol alters brain membrane functions

    Energy Technology Data Exchange (ETDEWEB)

    Sun, G.Y.; Sun, A.Y.; Schroeder, F.; Wood, G.; Strong, R.

    1986-03-05

    It has been well demonstrated that there is a direct correlation between increase in dolichol level in brain and aging. An abnormally high level of dolichol was found in brain tissue of patients with pathological aging disorders. The aim of this study is to examine the physiological significance of dolichol affecting membrane transport activity and phospholipid acyl group turnover. Dolichol added to synaptic plasma membranes resulted in a biphasic effect on (Na/sup +/, K/sup +/)-ATPase, i.e., an enhancement of activity at low concentrations (5 ..mu..g/125 mg protein) and an inhibition of activity at high concentrations (40-100 ..mu..g). To probe the membrane acyl group turnover, the incorporation of (/sup 14/C)-arachidonate into plasma membrane phospholipids was examined in the presence and absence of dolichol. Dolichol elicited an increase in the incorporation of label into phospholipids. However, the effects varied depending on whether BSA is present. In the absence of BSA, the increase in labeling of phosphatidylinositols is higher than that of phosphatidylcholines. These results suggest that dolichols, when inserted into membranes, may alter membrane functions.

  5. Fruit and Vegetable Quality Assessment via Dielectric Sensing.

    Science.gov (United States)

    El Khaled, Dalia; Novas, Nuria; Gazquez, Jose A; Garcia, Rosa M; Manzano-Agugliaro, Francisco

    2015-01-01

    The demand for improved food quality has been accompanied by a technological boost. This fact enhances the possibility of improving the quality of horticultural products, leading towards healthier consumption of fruits and vegetables. A better electrical characterization of the dielectric properties of fruits and vegetables is required for this purpose. Moreover, a focused study of dielectric spectroscopy and advanced dielectric sensing is a highly interesting topic. This review explains the dielectric property basics and classifies the dielectric spectroscopy measurement techniques. It comprehensively and chronologically covers the dielectric experiments explored for fruits and vegetables, along with their appropriate sensing instrumentation, analytical modelling methods and conclusions. An in-depth definition of dielectric spectroscopy and its usefulness in the electric characterization of food materials is presented, along with the various sensor techniques used for dielectric measurements. The collective data are tabulated in a summary of the dielectric findings in horticultural field investigations, which will facilitate more advanced and focused explorations in the future. PMID:26131680

  6. From biological membranes to biomimetic model membranes

    Directory of Open Access Journals (Sweden)

    Eeman, M.

    2010-01-01

    Full Text Available Biological membranes play an essential role in the cellular protection as well as in the control and the transport of nutrients. Many mechanisms such as molecular recognition, enzymatic catalysis, cellular adhesion and membrane fusion take place into the biological membranes. In 1972, Singer et al. provided a membrane model, called fluid mosaic model, in which each leaflet of the bilayer is formed by a homogeneous environment of lipids in a fluid state including globular assembling of proteins and glycoproteins. Since its conception in 1972, many developments were brought to this model in terms of composition and molecular organization. The main development of the fluid mosaic model was made by Simons et al. (1997 and Brown et al. (1997 who suggested that membrane lipids are organized into lateral microdomains (or lipid rafts with a specific composition and a molecular dynamic that are different to the composition and the dynamic of the surrounding liquid crystalline phase. The discovery of a phase separation in the plane of the membrane has induced an explosion in the research efforts related to the biology of cell membranes but also in the development of new technologies for the study of these biological systems. Due to the high complexity of biological membranes and in order to investigate the biological processes that occur on the membrane surface or within the membrane lipid bilayer, a large number of studies are performed using biomimicking model membranes. This paper aims at revisiting the fundamental properties of biological membranes in terms of membrane composition, membrane dynamic and molecular organization, as well as at describing the most common biomimicking models that are frequently used for investigating biological processes such as membrane fusion, membrane trafficking, pore formation as well as membrane interactions at a molecular level.

  7. Effect of ionizing radiation and calcium on plasma membrane structure

    International Nuclear Information System (INIS)

    Plasma membrane thymocytes were irradiated with doses of 10-104 Gy in the presence of 125 and 1125 μ mol of Ca2+ per 1 mg of membrane proteins. Fluorescence of 1-anilinonaphthalene-8-sulphonate and the degree of puren eximerization were determined. The data obtained indicate that calcium can exert a stabilizing effect on the plasma membrane structure affected by radiation

  8. Membrane metamaterial resonators with a sharp resonance: A comprehensive study towards practical terahertz filters and sensors

    Directory of Open Access Journals (Sweden)

    Yongyao Chen

    2012-06-01

    Full Text Available We investigate the resonant properties of high quality-factor membrane-based metamaterial resonators functioning in the terahertz regime. A number of factors, including the resonator geometry, dielectric loss, and most importantly the membrane thickness are found to extensively influence the resonance strength and quality factor of the sharp resonance. Further studies on the membrane thickness-dependent-sensitivity for sensing applications reveal that high quality-factor membrane metamaterials with a moderate thickness ranging from 10 to 50 μm are the most promising option towards developing realistic integrated terahertz filters and sensors.

  9. The ELBA force field for coarse-grain modeling of lipid membranes.

    Directory of Open Access Journals (Sweden)

    Mario Orsi

    Full Text Available A new coarse-grain model for molecular dynamics simulation of lipid membranes is presented. Following a simple and conventional approach, lipid molecules are modeled by spherical sites, each representing a group of several atoms. In contrast to common coarse-grain methods, two original (interdependent features are here adopted. First, the main electrostatics are modeled explicitly by charges and dipoles, which interact realistically through a relative dielectric constant of unity (ε(r = 1. Second, water molecules are represented individually through a new parametrization of the simple Stockmayer potential for polar fluids; each water molecule is therefore described by a single spherical site embedded with a point dipole. The force field is shown to accurately reproduce the main physical properties of single-species phospholipid bilayers comprising dioleoylphosphatidylcholine (DOPC and dioleoylphosphatidylethanolamine (DOPE in the liquid crystal phase, as well as distearoylphosphatidylcholine (DSPC in the liquid crystal and gel phases. Insights are presented into fundamental properties and phenomena that can be difficult or impossible to study with alternative computational or experimental methods. For example, we investigate the internal pressure distribution, dipole potential, lipid diffusion, and spontaneous self-assembly. Simulations lasting up to 1.5 microseconds were conducted for systems of different sizes (128, 512 and 1058 lipids; this also allowed us to identify size-dependent artifacts that are expected to affect membrane simulations in general. Future extensions and applications are discussed, particularly in relation to the methodology's inherent multiscale capabilities.

  10. Dielectric effect on electric fields in the vicinity of the metal–vacuum–dielectric junction

    Energy Technology Data Exchange (ETDEWEB)

    Chung, M.S., E-mail: mschung@ulsan.ac.kr [Department of Physics, University of Ulsan, San 29, Muga, Ulsan 680-749 (Korea, Republic of); Mayer, A. [FUNDP, University of Namur, Rue de Bruxelles 61, B-5000 Namur (Belgium); Miskovsky, N.M.; Weiss, B.L.; Cutler, P.H. [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)

    2013-09-15

    The dielectric effect was theoretically investigated in order to describe the electric field in the vicinity of a junction of a metal, dielectric, and vacuum. The assumption of two-dimensional symmetry of the junction leads to a simple analytic form and to a systematic numerical calculation for the field. The electric field obtained for the triple junction was found to be enhanced or reduced according to a certain criterion determined by the contact angles and dielectric constant. Further numerical calculations of the dielectric effect show that an electric field can experience a larger enhancement or reduction for a quadruple junction than that achieved for the triple junction. It was also found that even though it changes slowly in comparison with the shape effect, the dielectric effect was noticeably large over the entire range of the shape change. - Highlights: ► This work explains how a very strong electric field can be produced due to the dielectric in the vicinity of metal–dielectric contact. ► This work deals with configurations which enhance electric fields using the dielectric effect. The configuration is a type of junction at which metal, vacuum and dielectric meet. ► This work suggests the criterion to determine whether field enhancement occurs or not in the triple junction of metal, vacuum and dielectric. ► This work suggests that a quadruple junction is more effective in enhancing the electric field than a triple junction. The quadruple junction is formed by an additional vacuum portion to the triple junction. ► This work suggests that a triple junction can be a breakthrough candidate for a cold electron source.

  11. Current Trends about Inner Limiting Membrane Peeling in Surgery for Epiretinal Membranes

    OpenAIRE

    Francesco Semeraro; Francesco Morescalchi; Sarah Duse; Elena Gambicorti; Andrea Russo; Ciro Costagliola

    2015-01-01

    The inner limiting membrane (ILM) is the basement membrane of the Müller cells and can act as a scaffold for cellular proliferation in the pathophysiology of disorders affecting the vitreomacular interface. The atraumatic removal of the macular ILM has been proposed for treating various forms of tractional maculopathy in particular for macular pucker. In the last decade, the removal of ILM has become a routine practice in the surgery of the epiretinal membranes (ERMs), with good anatomical re...

  12. Dielectric properties of binary solutions a data handbook

    CERN Document Server

    Akhadov, Y Y

    1980-01-01

    Dielectric Properties of Binary Solutions focuses on the investigation of the dielectric properties of solutions, as well as the molecular interactions and mechanisms of molecular processes that occur in liquids. The book first discusses the fundamental formulas describing the dielectric properties of liquids and dielectric data for binary systems of non-aqueous solutions. Topics include permittivity and dielectric dispersion parameters of non-aqueous solutions of organic and inorganic compounds. The text also tackles dielectric data for binary systems of aqueous solutions, including permittiv

  13. Anaerobic membrane bioreactors: Are membranes really necessary?

    OpenAIRE

    Davila, M.; Kassab, G.; Klapwijk, A.; Van, Lier, G

    2008-01-01

    Membranes themselves represent a significant cost for the full scale application of anaerobic membrane bioreactors (AnMBR). The possibility of operating an AnMBR with a self-forming dynamic membrane generated by the substances present in the reactor liquor would translate into an important saving. A self-forming dynamic membrane only requires a support material over which a cake layer is formed, which determines the rejection properties of the system. The present research studies the applicat...

  14. Effect of erythrocytes oscillations on dielectric properties of human diabetic-blood

    Directory of Open Access Journals (Sweden)

    S. Abdalla

    2011-03-01

    Full Text Available It has been demonstrated that the erythrocytes (RBCs oscillate during their tank-treading motion with high-frequency oscillations. This oscillatory motion drastically affects the dielectric and electrical properties of RBCs. Moreover, the glucose level in blood affects the electrical and dielectric properties of blood. It has been, also, shown that the frequency of these oscillations exponentially decrease from 1.2 MHz down to 0.85 MHz with variation of glucose level from 85 mg/dL up to 346.1 mg/dL. It is expected that these oscillations strongly affect the general physiological properties of blood and would stimulate the curiosity of scientists and bioengineers to present new, more efficient, rapid, safe and viable diagnostic and/or therapeutic methods for blood disorders; in particular diabetes.

  15. Anaerobic membrane bioreactors: Are membranes really necessary?

    NARCIS (Netherlands)

    Davila, M.; Kassab, G.; Klapwijk, A.; Lier, van J.B.

    2008-01-01

    Membranes themselves represent a significant cost for the full scale application of anaerobic membrane bioreactors (AnMBR). The possibility of operating an AnMBR with a self-forming dynamic membrane generated by the substances present in the reactor liquor would translate into an important saving. A

  16. Physical basis of some membrane shaping mechanisms.

    Science.gov (United States)

    Simunovic, Mijo; Prévost, Coline; Callan-Jones, Andrew; Bassereau, Patricia

    2016-07-28

    In vesicular transport pathways, membrane proteins and lipids are internalized, externalized or transported within cells, not by bulk diffusion of single molecules, but embedded in the membrane of small vesicles or thin tubules. The formation of these 'transport carriers' follows sequential events: membrane bending, fission from the donor compartment, transport and eventually fusion with the acceptor membrane. A similar sequence is involved during the internalization of drug or gene carriers inside cells. These membrane-shaping events are generally mediated by proteins binding to membranes. The mechanisms behind these biological processes are actively studied both in the context of cell biology and biophysics. Bin/amphiphysin/Rvs (BAR) domain proteins are ideally suited for illustrating how simple soft matter principles can account for membrane deformation by proteins. We review here some experimental methods and corresponding theoretical models to measure how these proteins affect the mechanics and the shape of membranes. In more detail, we show how an experimental method employing optical tweezers to pull a tube from a giant vesicle may give important quantitative insights into the mechanism by which proteins sense and generate membrane curvature and the mechanism of membrane scission.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'. PMID:27298443

  17. Evaluation of high temperature capacitor dielectrics

    Science.gov (United States)

    Hammoud, Ahmad N.; Myers, Ira T.

    Experiments were carried out to evaluate four candidate materials for high temperature capacitor dielectric applications. The materials investigated were polybenzimidazole polymer and three aramid papers: Voltex 450, Nomex 410, and Nomex M 418, an aramid paper containing 50 percent mica. The samples were heat treated for six hours at 60 C and the direct current and 60 Hz alternating current breakdown voltages of both dry and impregnated samples were obtained in a temperature range of 20 to 250 C. The samples were also characterized in terms of their dielectric constant, dielectric loss, and conductivity over this temperature range with an electrical stress of 60 Hz, 50 V/mil present. Additional measurements are underway to determine the volume resistivity, thermal shrinkage, and weight loss of the materials. Preliminary data indicate that the heat treatment of the films slightly improves the dielectric properties with no influence on their breakdown behavior. Impregnation of the samples leads to significant increases in both alternating and direct current breakdown strength. The results are discussed and conclusions made concerning their suitability as high temperature capacitor dielectrics.

  18. Electromechanical stability of compressible dielectric elastomer actuators

    International Nuclear Information System (INIS)

    The constitutive relation and the electromechanical stability of Varga–Blatz–Ko-type compressible isotropic dielectric elastomers undergoing large deformation are investigated in this paper. Free energy in any form, which consists of elastic strain energy and electric field energy, can be applied to analyze the electromechanical stability of dielectric elastomers. The constitutive relation and the electromechanical stability are analyzed by applying a new kind of free energy model, which consists of elastic strain energy, composed of the Varga model as the volume conservative energy and the Blatz–Ko model as the volume non-conservative energy, and electric field energy with constant permittivity. The ratio between the principal planar stretches, the ratio between the thickness and length direction stretches, and the power exponent of the stretch are defined to characterize the mechanical loading behavior and compressible behavior of the dielectric elastomer. Along with the increase of these parameters, which determine the shape or volume of the elastomer, and the Poisson ratio, the critical nominal electric field is higher, which indicates a more stable dielectric elastomer electromechanical system. In contrast, with the decrease of the dimensionless material parameter α of the Varga elastic strain energy, the critical nominal electric field increases. The coupling system becomes more stable. We further demonstrate that the critical nominal electric field of the compressible dielectric elastomer electromechanical coupling system is significantly influenced by the ratio between the principal planar stretches

  19. Accelerating Dielectrics Design Using Thinking Machines

    Science.gov (United States)

    Ramprasad, R.

    2013-03-01

    High energy density capacitors are required for several pulsed power and energy storage applications, including food preservation, nuclear test simulations, electric propulsion of ships and hybrid electric vehicles. The maximum electrostatic energy that can be stored in a capacitor dielectric is proportional to its dielectric constant and the square of its breakdown field. The current standard material for capacitive energy storage is polypropylene which has a large breakdown field but low dielectric constant. We are involved in a search for new classes of polymers superior to polypropylene using first principles computations combined with statistical and machine learning methods. Essential to this search are schemes to efficiently compute the dielectric constant of polymers and the intrinsic dielectric breakdown field, as well as methods to determine the stable structures of new classes of polymers and strategies to efficiently navigate through the polymer chemical space offered by the periodic table. These methodologies have been combined with statistical learning paradigms in order to make property predictions rapidly, and promising classes of polymeric systems for energy storage applications have been identified. This work is being supported by the Office of Naval Research.

  20. Dielectric Genome of van der Waals Heterostructures.

    Science.gov (United States)

    Andersen, Kirsten; Latini, Simone; Thygesen, Kristian S

    2015-07-01

    Vertical stacking of two-dimensional (2D) crystals, such as graphene and hexagonal boron nitride, has recently lead to a new class of materials known as van der Waals heterostructures (vdWHs) with unique and highly tunable electronic properties. Ab initio calculations should in principle provide a powerful tool for modeling and guiding the design of vdWHs, but in their traditional form such calculations are only feasible for commensurable structures with a few layers. Here we show that the dielectric properties of realistic, incommensurable vdWHs comprising hundreds of layers can be efficiently calculated using a multiscale approach where the dielectric functions of the individual layers (the dielectric building blocks) are computed ab initio and coupled together via the long-range Coulomb interaction. We use the method to illustrate the 2D-3D transition of the dielectric function of multilayer MoS2 crystals, the hybridization of quantum plasmons in thick graphene/hBN heterostructures, and to demonstrate the intricate effect of substrate screening on the non-Rydberg exciton series in supported WS2. The dielectric building blocks for a variety of 2D crystals are available in an open database together with the software for solving the coupled electrodynamic equations. PMID:26047386

  1. Extension of the FACTS Implicit Solvation Model to Membranes.

    Science.gov (United States)

    Carballo-Pacheco, Martín; Vancea, Ioan; Strodel, Birgit

    2014-08-12

    The generalized Born (GB) formalism can be used to model water as a dielectric continuum. Among the different implicit solvent models using the GB formalism, FACTS is one of the fastest. Here, we extend FACTS so that it can represent a membrane environment. This extension is accomplished by considering a position dependent dielectric constant and empirical surface tension parameter. For the calculation of the effective Born radii in different dielectric environments we present a parameter-free approximation to Kirkwood's equation, which uses the Born radii obtained with FACTS for the water environment as input. This approximation is tested for the calculation of self-free energies, pairwise interaction energies in solution and solvation free energies of complete protein conformations. The results compare well to those from the finite difference Poisson method. The new implicit membrane model is applied to estimate free energy insertion profiles of amino acid analogues and in molecular dynamics simulations of melittin, WALP23 and KALP23, glycophorin A, bacteriorhodopsin, and a Clc channel dimer. In all cases, the results agree qualitatively with experiments and explicit solvent simulations. Moreover, the implicit membrane model is only six times slower than a vacuum simulation. PMID:26588287

  2. Characteristics of PVDF Membranes Irradiated by Electron Beam.

    Science.gov (United States)

    Jaleh, Babak; Gavary, Negin; Fakhri, Parisa; Muensit, Nakatan; Taheri, Soheil Mohammad

    2015-01-01

    Polyvinylidene fluoride (PVDF) membranes were exposed vertically to a high energy electron beam (EB) in air, at room temperature. The chemical changes were examined by Fourier Transform Infrared Spectroscopy (FTIR). The surface morphologies were studied by Scanning Electron Microscopy (SEM) and showed some changes in the pore size. Thermogravimetric (TGA) analysis represented an increase in the thermal stability of PVDF due to irradiation. Electron paramagnetic resonance (EPR) showed the presence of free radicals in the irradiated PVDF. The effect of EB irradiation on the electrical properties of the membranes was analyzed in order to determine the dielectric constant, and an increase in the dielectric constant was found on increasing the dose. The surface hydrophilicity of the modified membrane was characterized by water contact angle measurement. The contact angle decreased compared to the original angle, indicating an improvement of surface hydrophilicity. Filtration results also showed that the pure water flux (PWF) of the modified membrane was lower than that of the unirradiated membrane. PMID:25569360

  3. Characteristics of PVDF Membranes Irradiated by Electron Beam

    Directory of Open Access Journals (Sweden)

    Babak Jaleh

    2015-01-01

    Full Text Available Polyvinylidene fluoride (PVDF membranes were exposed vertically to a high energy electron beam (EB in air, at room temperature. The chemical changes were examined by Fourier Transform Infrared Spectroscopy (FTIR. The surface morphologies were studied by Scanning Electron Microscopy (SEM and showed some changes in the pore size. Thermogravimetric (TGA analysis represented an increase in the thermal stability of PVDF due to irradiation. Electron paramagnetic resonance (EPR showed the presence of free radicals in the irradiated PVDF. The effect of EB irradiation on the electrical properties of the membranes was analyzed in order to determine the dielectric constant, and an increase in the dielectric constant was found on increasing the dose. The surface hydrophilicity of the modified membrane was characterized by water contact angle measurement. The contact angle decreased compared to the original angle, indicating an improvement of surface hydrophilicity. Filtration results also showed that the pure water flux (PWF of the modified membrane was lower than that of the unirradiated membrane.

  4. Dielectric properties and electronic transitions of porous and nanostructured cerium oxide films

    International Nuclear Information System (INIS)

    Cerium dioxide (CeO2) exhibits exceptional electronic properties such as optical transparency and high refractive index (n) and high dc dielectric constant (k). Therefore, it is an attractive material for ultra-thin gate oxide in CMOS technology, where high-k dielectrics are required. We study the electronic properties of nanostructured and porous cerium oxide (CeOx) films, 110-500 nm thick, grown on Si by electron beam evaporation (EBE) and ion beam assisted deposition (IBAD). The film microstructure and morphology (grain size, porosity, defect concentration, surface and interface roughness) are controlled by varying the process parameters appropriately. They have been studied by high-resolution and transmission electron microscopy (HRTEM). The optical properties have been studied by spectroscopic ellipsometry (SE) and k was determined by capacitance measurements. We have found that the values of k and n (1.6-2.5 depending on porosity) are affected by the electronic transitions, which are strongly correlated with the microstructure and morphology of the films. We investigate how the microstructure and morphology variations affect the absolute values of the dc dielectric constant and of the dielectric function at the UV-Vis and IR spectral regions. In addition, we investigate the very important role of the defects, which have the form of grain boundaries, trivalent Ce3+ and O vacancies. As a result we were able to tailor n and k of CeOx films controlling their porosity and defect density

  5. Membrane resistance: The effect of salinity gradients over a cation exchange membrane

    NARCIS (Netherlands)

    Galama, A.H.; Vermaas, D.A.; Veerman, J.; Saakes, M.; Rijnaarts, H.; Post, J.W.; Nijmeijer, K.

    2014-01-01

    Ion exchange membranes (IEMs) are used for selective transport of ions between two solutions. These solutions are often different in concentration or composition. The membrane resistance (R-M) is an important parameter affecting power consumption or power production in electrodialytic processes. In

  6. Membrane resistance : The effect of salinity gradients over a cation exchange membrane

    NARCIS (Netherlands)

    Galama, A. H.; Vermaas, D. A.; Veerman, J.; Saakes, M.; Rijnaarts, H. H. M.; Post, J. W.; Nijmeijer, K.

    2014-01-01

    Ion exchange membranes (IEMs) are used for selective transport of ions between two solutions. These solutions are often different in concentration or composition. The membrane resistance (R-M) is an important parameter affecting power consumption or power production in electrodialytic processes. In

  7. Numerical calculation of the dielectric and electrokinetic properties of vesicle suspensions.

    Science.gov (United States)

    Grosse, Constantino; Zimmerman, Viviana

    2005-09-29

    The dielectric and electrokinetic properties of aqueous suspensions of vesicles (unilamellar liposomes) are numerically calculated in the 1 Hz to 1 GHz frequency range using a network simulation method. The model consists of a conducting internal medium surrounded by an insulating membrane with fixed surface charges on both sides. Without an applied field, the internal medium is in electric equilibrium with the external one, so that it also bears a net volume charge. Therefore, in the presence of an applied ac field, there is fluid flow both in the internal and in the external media. The obtained results are qualitatively different from those corresponding to suspensions of charged homogeneous particles, mainly due to the existence of an additional length scale (the membrane thickness) and the corresponding dispersion mechanism, charging of the membrane. Because of this dispersion, the shapes of the spectra change with the size of the particles (at constant zeta potential and particle radius to Debye length ratio) instead of merely shifting along the frequency axis. A comparison between the numerical results and those obtained using approximate analytical expressions shows deviations that are, in general, sufficiently large enough to show the necessity to use numerical results in order to interpret broad frequency range dielectric and electrokinetic measurements of vesicle suspensions. PMID:16853323

  8. Erythrocyte membrane proteins and membrane skeleton

    Institute of Scientific and Technical Information of China (English)

    LU Yiqin; LIU Junfan

    2007-01-01

    Considerable advances in the research field of erythrocyte membrane were achieved in the recent two decades.New findings in the structure-function correlation and interactions of erythrocyte membrane proteins have attracted extensive attention.Interesting progress was also made in the molecular pathogenesis of erythrocyte membrane disorders.Advances in the composition,function and interaction of erythrocyte membrane proteins,erythrocyte membrane skeleton,and relevant diseases are briefly described and summarized here on the basis of domestic and world literatures.

  9. Near-Critical Fluctuations and Cytoskeleton-Assisted Phase Separation Lead to Subdiffusion in Cell Membranes

    OpenAIRE

    Ehrig, Jens; Petrov, Eugene P.; Schwille, Petra

    2011-01-01

    We address the relationship between membrane microheterogeneity and anomalous subdiffusion in cell membranes by carrying out Monte Carlo simulations of two-component lipid membranes. We find that near-critical fluctuations in the membrane lead to transient subdiffusion, while membrane-cytoskeleton interaction strongly affects phase separation, enhances subdiffusion, and eventually leads to hop diffusion of lipids. Thus, we present a minimum realistic model for membrane rafts showing the featu...

  10. Terajets produced by 3D dielectric cuboids

    CERN Document Server

    Pacheco-Peña, V; Minin, I V; Minin, O V

    2014-01-01

    The capability of generating terajets using 3D dielectric cuboids working at terahertz (THz) frequencies (as analogues of nanojets in the infrared band) are introduced and studied numerically. The focusing performance of the terajets are evaluated in terms of the transversal full width at half maximum along x- and y- directions using different refractive indexes for a 3D dielectric cuboid with a fixed geometry, obtaining a quasi-symmetric terajet with a subwavelength resolution of ~0.46{\\lambda}0 when the refractive index is n = 1.41. Moreover, the backscattering enhancement produced when metal particles are introduced in the terajet region is demonstrated for a 3D dielectric cuboid and compared with its 2D counterpart. The results of the jet generated for the 3D case are experimentally validated at sub-THz waves, demonstrating the ability to produce terajets using 3D cuboids.

  11. Studies on metal-dielectric plasmonic structures.

    Energy Technology Data Exchange (ETDEWEB)

    Chettiar, Uday K. (Purdue University, West Lafayette, IN); Liu, Zhengtong (Purdue University, West Lafayette, IN); Thoreson, Mark D. (Purdue University, West Lafayette, IN); Shalaev, Vladimir M. (Purdue University, West Lafayette, IN); Drachev, Vladimir P. (Purdue University, West Lafayette, IN); Pack, Michael Vern; Kildishev, Alexander V. (Purdue University, West Lafayette, IN); Nyga, Piotr (Purdue University, West Lafayette, IN)

    2010-01-01

    The interaction of light with nanostructured metal leads to a number of fascinating phenomena, including plasmon oscillations that can be harnessed for a variety of cutting-edge applications. Plasmon oscillation modes are the collective oscillation of free electrons in metals under incident light. Previously, surface plasmon modes have been used for communication, sensing, nonlinear optics and novel physics studies. In this report, we describe the scientific research completed on metal-dielectric plasmonic films accomplished during a multi-year Purdue Excellence in Science and Engineering Graduate Fellowship sponsored by Sandia National Laboratories. A variety of plasmonic structures, from random 2D metal-dielectric films to 3D composite metal-dielectric films, have been studied in this research for applications such as surface-enhanced Raman sensing, tunable superlenses with resolutions beyond the diffraction limit, enhanced molecular absorption, infrared obscurants, and other real-world applications.

  12. Multimode directionality in all-dielectric metasurfaces

    CERN Document Server

    Yang, Yuanqing; Kostinski, Sarah V; Odit, Mikhail; Kapitanova, Polina; Qiu, Min; Kivshar, Yuri

    2016-01-01

    All-dielectric resonant nanophotonics has emerged recently as a new direction of research aiming at the manipulation of strong optically-induced electric and magnetic Mie resonances in dielectric nanoparticles with high refractive index, for a design of metadevices with reduced dissipative losses and large resonant enhancement of both electric and magnetic fields. Usually, the geometry of dielectric nanoparticles is considered to be close to either sphere or rod, so the exact Mie solutions of the scattering problem are applied. Here we study nanoparticles with a large aspect ratio (such as nanobars) and describe a novel type of hybrid Mie-Fabry-Perot modes responsible for the existence of multiple magnetic dipole resonances. The multiple magnetic dipoles originate from a combination of a magnetic dipolar mode and a number of standing waves of an elongated anisotropic nanobar. We reveal that these novel hybrid modes can interfere constructively with the induced electric dipoles and thereby lead to multimode un...

  13. Dielectric and phase behavior of dipolar spheroids.

    Science.gov (United States)

    Johnson, Lewis E; Benight, Stephanie J; Barnes, Robin; Robinson, Bruce H

    2015-04-23

    The Stockmayer fluid, composed of dipolar spheres, has a well-known isotropic-ferroelectric phase transition at high dipole densities. However, there has been little investigation of the ferroelectric transition in nearly spherical fluids at dipole densities corresponding to those found in many polar solvents and in guest-host organic electro-optic materials. In this work, we examine the transition to ordered phases of low-aspect-ratio spheroids under both unperturbed and poled conditions, characterizing both the static dielectric response and thermodynamic properties of spheroidal systems. Spontaneous ferroelectric ordering was confined to a small region of aspect ratios about unity, indicating that subtle changes in sterics can have substantial influence on the behavior of coarse-grained liquid models. Our results demonstrate the importance of molecular shape in obtaining even qualitatively correct dielectric responses and provide an explanation for the success of the Onsager model as a phenomenological representation for the dielectric behavior of polar organic liquids. PMID:25821921

  14. On equilibrium charge distribution above dielectric surface

    Directory of Open Access Journals (Sweden)

    Yu.V. Slyusarenko

    2009-01-01

    Full Text Available The problem of the equilibrium state of the charged many-particle system above dielectric surface is formulated. We consider the case of the presence of the external attractive pressing field and the case of its absence. The equilibrium distributions of charges and the electric field, which is generated by these charges in the system in the case of ideally plane dielectric surface, are obtained. The solution of electrostatic equations of the system under consideration in case of small spatial heterogeneities caused by the dielectric surface, is also obtained. These spatial inhomogeneities can be caused both by the inhomogeneities of the surface and by the inhomogeneous charge distribution upon it. In particular, the case of the "wavy" spatially periodic surface is considered taking into account the possible presence of the surface charges.

  15. TE resonances in graphene-dielectric structures

    CERN Document Server

    Werra, Julia F M; Busch, Kurt

    2015-01-01

    An investigation of the dispersion relations of TE resonances in different graphene-dielectric structures is presented. When a graphene layer is brought into contact with a dielectric material, a gap can appear in its electric band structure. This allows for the formation of TE-plasmons with unusual dispersion relations. In addition, if the dielectric has a finite thickness, graphene acts as a mode filter and strongly modifies the behavior of the waveguiding modes by introducing a frequency cutoff. This cutoff and the properties of TE-plasmons are closely related to the pair-creation threshold of graphene thus representing quantum mechanical effects that manifest themselves in the electromagnetic response. Our findings are of particular relevance to all forms of light-matter interaction in graphene-based systems, notably for the decay rates of emitters that are in close proximity to graphene.

  16. High efficiency dielectric metasurfaces at visible wavelengths

    CERN Document Server

    Devlin, Robert C; Chen, Wei-Ting; Oh, Jaewon; Capasso, Federico

    2016-01-01

    Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics1-3. Dielectric metasurfaces demonstrated thus far4-10 are limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. It is critical that new materials and fabrication techniques be developed for dielectric metasurfaces at visible wavelengths to enable applications such as three-dimensional displays, wearable optics and planar optical systems11. Here, we demonstrate high performance titanium dioxide dielectric metasurfaces in the form of holograms for red, green and blue wavelengths with record absolute efficiency (>78%). We use atomic layer deposition of amorphous titanium dioxide that exhibits low surface roughness of 0.738 nm and ideal optical properties. To fabricate the metasurfaces we use a lift-off-like process that allows us to produce highly anisotropic nanofins with shape birefringence. This ...

  17. Novel Low Temperature Co-Fired Ceramic Material System Composed of Dielectrics with Different Dielectric Constants

    Science.gov (United States)

    Sakamoto, Sadaaki; Adachi, Hiroshige; Kaneko, Kazuhiro; Sugimoto, Yasutaka; Takada, Takahiro

    2013-09-01

    We found that the co-firing low temperature co-fired ceramic (LTCC) materials of different dielectric constants (ɛr) with Cu wiring is achievable using a novel, original design. It was confirmed that the dielectric characteristics of the dielectrics designed in this study are very suitable for the use of the dielectrics in electronic components such as filters mounted in high-speed radio communication equipment. The dielectric constants of the lower- and higher-dielectric-coefficient materials were 8.1 and 44.5, respectively, which are sufficiently effective for downsizing LTCC components. Observing the co-fired interface, it was confirmed that excellent co-firing conditions resulted in no mechanical defects such as delamination or cracks. On the basis of the results of wavelength dispersive X-ray spectrometry (WDX) and X-ray diffractometry (XRD), it was confirmed that co-firing with minimal interdiffusion was realized using the same glass for both dielectrics. It is concluded that the materials developed are good for co-firing in terms of the mechanical defects and interdiffusion that appear in them.

  18. Selective effect of cell membrane on synaptic neurotransmission

    Science.gov (United States)

    Postila, Pekka A.; Vattulainen, Ilpo; Róg, Tomasz

    2016-01-01

    Atomistic molecular dynamics simulations were performed with 13 non-peptidic neurotransmitters (NTs) in three different membrane environments. The results provide compelling evidence that NTs are divided into membrane-binding and membrane-nonbinding molecules. NTs adhere to the postsynaptic membrane surface whenever the ligand-binding sites of their synaptic receptors are buried in the lipid bilayer. In contrast, NTs that have extracellular ligand-binding sites do not have a similar tendency to adhere to the membrane surface. This finding is a seemingly simple yet important addition to the paradigm of neurotransmission, essentially dividing it into membrane-independent and membrane-dependent mechanisms. Moreover, the simulations also indicate that the lipid composition especially in terms of charged lipids can affect the membrane partitioning of NTs. The revised paradigm, highlighting the importance of cell membrane and specific lipids for neurotransmission, should to be of interest to neuroscientists, drug industry and the general public alike.

  19. Salt Concentration Differences Alter Membrane Resistance in Reverse Electrodialysis Stacks

    KAUST Repository

    Geise, Geoffrey M.

    2014-01-14

    Membrane ionic resistance is usually measured by immersing the membrane in a salt solution at a single, fixed concentration. While salt concentration is known to affect membrane resistance when the same concentration is used on both sides of the membrane, little is known about membrane resistance when the membrane is placed between solutions of different concentrations, such as in a reverse electrodialysis (RED) stack. Ionic resistance measurements obtained using Selemion CMV and AMV that separated sodium chloride and ammonium bicarbonate solutions of different concentrations were greater than those measured using only the high-concentration solution. Measured RED stack resistances showed good agreement with resistances calculated using an equivalent series resistance model, where the membranes accounted for 46% of the total stack resistance. The high area resistance of the membranes separating different salt concentration solutions has implications for modeling and optimizing membranes used in RED systems.

  20. Selective effect of cell membrane on synaptic neurotransmission.

    Science.gov (United States)

    Postila, Pekka A; Vattulainen, Ilpo; Róg, Tomasz

    2016-01-01

    Atomistic molecular dynamics simulations were performed with 13 non-peptidic neurotransmitters (NTs) in three different membrane environments. The results provide compelling evidence that NTs are divided into membrane-binding and membrane-nonbinding molecules. NTs adhere to the postsynaptic membrane surface whenever the ligand-binding sites of their synaptic receptors are buried in the lipid bilayer. In contrast, NTs that have extracellular ligand-binding sites do not have a similar tendency to adhere to the membrane surface. This finding is a seemingly simple yet important addition to the paradigm of neurotransmission, essentially dividing it into membrane-independent and membrane-dependent mechanisms. Moreover, the simulations also indicate that the lipid composition especially in terms of charged lipids can affect the membrane partitioning of NTs. The revised paradigm, highlighting the importance of cell membrane and specific lipids for neurotransmission, should to be of interest to neuroscientists, drug industry and the general public alike. PMID:26782980

  1. A membrane disdrometer based on membrane vibration

    International Nuclear Information System (INIS)

    Raindrop sizes were indirectly determined through the distinctive vibrations and sounds that occur when raindrops of different sizes impact on a membrane. The relationships between diameter, raindrop kinetic momentum, membrane deflection, and impact force were analyzed. Membrane deflection and vibration models were created, and the optimum membrane diameter and thickness were identified. A prototype membrane disdrometer was developed on the basis of these findings. The relationship between raindrop size and membrane vibration sound pressure was determined experimentally. The fundamental parameter of raindrop size recognition was used. The test results indicate that raindrops 0.4–2.0 mm in diameter can be detected by the proposed membrane disdrometer, and 50 raindrops per second in a zone area of 28.3 cm2 can be detected in natural rain. (paper)

  2. Dielectric loss against piezoelectric power harvesting

    International Nuclear Information System (INIS)

    Piezoelectricity is one of the most popular electromechanical transduction mechanisms for constructing kinetic energy harvesting systems. When a standard energy harvesting (SEH) interface circuit, i.e., bridge rectifier plus filter capacitor, is utilized for collecting piezoelectric power, the previous literature showed that the power conversion can be well predicted without much consideration for the effect of dielectric loss. Yet, as the conversion power gets higher by adopting power-boosting interface circuits, such as synchronized switch harvesting on inductor (SSHI), the neglect of dielectric loss might give rise to deviation in harvested power estimation. Given the continuous progress on power-boosting interface circuits, the role of dielectric loss in practical piezoelectric energy harvesting (PEH) systems should receive attention with better evaluation. Based on the integrated equivalent impedance network model, this fast track communication provides a comprehensive study on the susceptibility of harvested power in PEH systems under different conditions. It shows that, dielectric loss always counteracts piezoelectric power harvesting by causing charge leakage across piezoelectric capacitance. In particular, taking corresponding ideal lossless cases as references, the counteractive effect might be aggravated under one of the five conditions: larger dielectric loss tangent, lower vibration frequency, further away from resonance, weaker electromechanical coupling, or using power-boosting interface circuit. These relationships are valuable for the study of PEH systems, as they not only help explain the role of dielectric loss in piezoelectric power harvesting, but also add complementary insights for material, structure, excitation, and circuit considerations towards holistic evaluation and design for practical PEH systems. (fast track communications)

  3. Dielectric properties of alumina/zirconia composites at millimeter wavelengths

    International Nuclear Information System (INIS)

    Alumina-zirconia composites with ZrO2 contents up to 20% and negligible porosity were investigated at millimeter (mm) wavelengths to determine the changes appearing in the dielectric properties of pure alumina ceramics when unstabilized or partially stabilized ZrO2 is added to improve the mechanical strength. It is demonstrated that it essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia (m-ZrO2, t-ZrO2). Permittivity is raised with increasing content of either phases; the effective permittivity can be assessed by the rule of mixtures (Maxwell-Garnett formulation of the generalized Clasussius-Mossotti relation) using permittivity values of 10 for Al2O3, 14-21 for m-ZrO2 and 40-45 for t-ZrO2. The permittivity data show only a small variation in the investigated range of 9-145 GHz. For the dielectric loss, there is evidence of a predominant contribution of m-ZrO2; in addition, the marked increase in loss with frequency becomes sharper. The t-ZrO2, which is responsible for strengthening, does not show any significant influence on losses. It is therefore concluded, that ZrO2 strengthening of alumina is feasible without affecting mm-wave losses at room temperature as long as the presence of m-ZrO2 is avoided

  4. Effects of high-energy electron radiation on polypropylene dielectric

    International Nuclear Information System (INIS)

    Polypropylene, a polymeric materials widely used as the main dielectric in many high-voltage components such as capacitors and cables, was exposed to electron irradiation in air at room temperature. The 25.4-μm-thick dry polypropylene films were irradiated to different doses up to 108 rads with electron beam having energies of 0.5, 1.0, and 1.5 MeV. Monoisopropyl biphenyl (MIPB)-impregnated polypropylene films were also exposed to 1-MeV electron beam to doses up to 108 rads and the post-irradiation effects on the electrical, mechanical, and morphological and chemical properties of the films were evaluated. The electrical properties included the AC, DC and pulsed breakdown strengths, dielectric constant, dissipation factor, conductivity, and pulsed life-endurance. The mechanical properties comprised the Young's modulus, elongation-at-break, tensile strength, complex modulus, and mechanical loss. Finally, the morphological and chemical diagnoses carried out included surface morphology, elemental analysis, crystallinity changes, and identification of newly formed bonds and degree of oxidation. The results obtained indicate that the dry polypropylene films started to exhibit degradation at doses as low as 106 rads. The properties that were mostly affected included the film's tensile properties, pulsed life, dissipation factor, and electrical conductivity

  5. Dynamics within alkylsiloxane SAMs studied by sensitive dielectric spectroscopy

    Science.gov (United States)

    Scott, Mary; Stevens, Derrick; Bochinski, Jason; Clarke, Laura

    2009-03-01

    Self assembled monolayers (SAMs) are a ubiquitous tool in modern research and their static structure has been extensively studied. Fewer investigations have addressed dynamics within these systems; however, such motions within SAMs will affect surface properties such as friction and blocking ability (permeability). In this study, sensitive, dielectric spectroscopy over a broad temperature range (4-400 K) has been employed to study relaxations within planar alkylsiloxane SAMs[1] . Highly disordered SAMs of varying density were grown by vapor deposition. Two dielectric relaxations were observed. The first, a polyethylene-like relaxation similar to that previously reported in phase-segregated alkyl side-chain polymers, is observed for all films with alkyl chains containing four or more carbons. This is an interacting or glassy relaxation. The second motion, which is observable only at high film densities, is a local mode, which follows an Arrhenius dependence on temperature, and has been previously assigned to a sub-chain rotation. [1] M.C. Scott, D.R. Stevens, J.R. Bochinski, L.I. Clarke, ACS Nano. DOI: 10.1021/nn800543j.

  6. Method for fabrication of crack-free ceramic dielectric films

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Beihai; Narayanan, Manoj; Balachandran, Uthamalingam; Chao, Sheng; Liu, Shanshan

    2016-05-31

    The invention provides a process for forming crack-free dielectric films on a substrate. The process comprises the application of a dielectric precursor layer of a thickness from about 0.3 .mu.m to about 1.0 .mu.m to a substrate. The deposition is followed by low temperature heat pretreatment, prepyrolysis, pyrolysis and crystallization step for each layer. The deposition, heat pretreatment, prepyrolysis, pyrolysis and crystallization are repeated until the dielectric film forms an overall thickness of from about 1.5 .mu.m to about 20.0 .mu.m and providing a final crystallization treatment to form a thick dielectric film. The process provides a thick crack-free dielectric film on a substrate, the dielectric forming a dense thick crack-free dielectric having an overall dielectric thickness of from about 1.5 .mu.m to about 20.0 .mu.m.

  7. Method for fabrication of crack-free ceramic dielectric films

    Science.gov (United States)

    Ma, Beihai; Balachandran, Uthamalingam; Chao, Sheng; Liu, Shanshan; Narayanan, Manoj

    2014-02-11

    The invention provides a process for forming crack-free dielectric films on a substrate. The process comprise the application of a dielectric precursor layer of a thickness from about 0.3 .mu.m to about 1.0 .mu.m to a substrate. The deposition is followed by low temperature heat pretreatment, prepyrolysis, pyrolysis and crystallization step for each layer. The deposition, heat pretreatment, prepyrolysis, pyrolysis and crystallization are repeated until the dielectric film forms an overall thickness of from about 1.5 .mu.m to about 20.0 .mu.m and providing a final crystallization treatment to form a thick dielectric film. Also provided was a thick crack-free dielectric film on a substrate, the dielectric forming a dense thick crack-free dielectric having an overall dielectric thickness of from about 1.5 .mu.m to about 20.0 .mu.m.

  8. Dispersion analysis with inverse dielectric function modelling.

    Science.gov (United States)

    Mayerhöfer, Thomas G; Ivanovski, Vladimir; Popp, Jürgen

    2016-11-01

    We investigate how dispersion analysis can profit from the use of a Lorentz-type description of the inverse dielectric function. In particular at higher angles of incidence, reflectance spectra using p-polarized light are dominated by bands from modes that have their transition moments perpendicular to the surface. Accordingly, the spectra increasingly resemble inverse dielectric functions. A corresponding description can therefore eliminate the complex dependencies of the dispersion parameters, allow their determination and facilitate a more accurate description of the optical properties of single crystals. PMID:27294550

  9. Polariton spectrum in nonlinear dielectric medium

    CERN Document Server

    Dzedolik, Igor V

    2012-01-01

    We obtain theoretically the phonon-polariton spectrum in nonlinear dielectric medium with the third order Kerr-type nonlinearity. We investigate the dependence of number of the polariton spectrum branches on the intensity of electromagnetic field and demonstrate that the appearance of new branches located in the polariton spectrum gap is caused by the influence of dispersion of the third order dielectric susceptibility at intensity field in the medium. The modulation instability of new branch waves leading to appearance of cnoidal waves and solitons.

  10. Polariton waves in nonlinear dielectric medium

    CERN Document Server

    Dzedolik, I V

    2012-01-01

    The phonon-polariton spectrum in dielectric medium with the third order nonlinearity was theoretically obtained. Dependence of number of polariton spectrum branches on intensity of electromagnetic field was investigated. The appearance of new branches located in the polariton spectrum gap was caused by the influence of dispersion of the third order dielectric susceptibility at increment of the field intensity in the medium. The soliton and cnoidal wave solutions for the polariton excitations for these new spectrum branches were obtained. The all-optical logic gates OR and NOT are proposed as an example of the theory application.

  11. Polariton spectrum in nonlinear dielectric medium.

    Science.gov (United States)

    Dzedolik, Igor V; Karakchieva, Olga

    2013-05-01

    We obtain theoretically the phonon-polariton spectrum in nonlinear dielectric medium with the third-order Kerr-type nonlinearity. We investigate the dependence of number of the polariton spectrum branches on the intensity of electromagnetic field and demonstrate that the appearance of new branches located in the polariton spectrum gap is caused by the influence of dispersion of the third-order dielectric susceptibility at the intensive electromagnetic field in the medium. The modulation instability of new spectrum branch waves leads to the appearance of the cnoidal waves or solitons. These new nonlinear waves one can use for designing optical devices such as the nonlinear optical filter converter. PMID:23669776

  12. Dielectric properties of nanosilica filled epoxy nanocomposites

    Indian Academy of Sciences (India)

    M G VEENA; N M RENUKAPPA; KUNIGAL N SHIVAKUMAR; S SEETHARAMU

    2016-04-01

    This paper presents the development of epoxy-silica nanocomposites and characterized for dielectric properties. The effect of nanosilica loading (0–20 wt%), frequency, temperature and sea water aging on these properties was studied. Transmission electron microscopy (TEM) analysis of the samples showed an excellent dispersion. However, at higher silica loading TEM showed inter-contactity of the particles. The dielectric constant (υ') increased with silica loading and reached an optimum at about 10 wt%. The υ' of the nanocomposites showed linear decrease with frequency whereas AC conductivity (σac) increases. The σac and υ' increased marginally with temperature and sea water aging.

  13. Wave excitation in inhomogeneous dielectric media.

    Science.gov (United States)

    Cary, John R; Xiang, Nong

    2007-11-01

    The equation describing the propagation of a mode driven by external currents in an inhomogeneous dielectric is derived from the principle of the conservation of wave energy density and wave momentum density. The wave amplitude in steady state is obtained in terms of a simple spatial integration of the driving current. The contribution from the spatial derivative of the dielectric response is found to be important. The analytical predictions are verified through comparison with deltaf particle-in-cell computations of electron Bernstein wave propagation, thus showing applicability to kinetic systems. PMID:18233709

  14. Development of dielectric barrier discharging power supply

    Science.gov (United States)

    Gao, Yinghui; Liu, Kun; Fu, Rongyao; Sun, Yaohong; Yan, Ping

    2015-11-01

    Due to the demand of a dielectric barrier discharge power supply, a high voltage and high frequency AC power supply was designed and implemented. Its output voltage is standard or approximate standard sine waveform with the frequency range of 1 kHz to 50 kHz. The output voltage and output frequency can be adjusted individually. The maximum output power of the power supply is 2 kW. It can be operated through local or remote control. The power supply has been used in the dielectric barrier discharging research under different conditions.

  15. Dielectric Engineered Tunnel Field-Effect Transistor

    OpenAIRE

    Ilatikhameneh, Hesameddin; Tarek A. Ameen; Klimeck, Gerhard; Appenzeller, Joerg; Rahman, Rajib

    2015-01-01

    The dielectric engineered tunnel field-effect transistor (DE-TFET) as a high performance steep transistor is proposed. In this device, a combination of high-k and low-k dielectrics results in a high electric field at the tunnel junction. As a result a record ON-current of about 1000 uA/um and a subthreshold swing (SS) below 20mV/dec are predicted for WTe2 DE-TFET. The proposed TFET works based on a homojunction channel and electrically doped contacts both of which are immune to interface stat...

  16. Optical dielectric function of intrinsic amorphous silicon

    International Nuclear Information System (INIS)

    The imaginary part of the optical dielectric function epsilon2(ω) has been calculated using a continuous-random-tetrahedral network as the structural model for the atomic positions. Here the electronic energies and wave functions are determined by first-principles calculations with the method of linear combinations of atomic orbitals (LCAO), and the momentum matrix elements are evaluated directly from the LCAO wave functions. The calculated dielectric function is in good overall agreement with experiment. At energies within 1 eV above the threshold, the epsilon2 curve shows some structures that are due to interband transitions between the localized states near the band gap

  17. Silicone elastomers with high dielectric permittivity and high dielectric breakdown strength based on tunable functionalized copolymers

    DEFF Research Database (Denmark)

    Madsen, Frederikke Bahrt; Yu, Liyun; Daugaard, Anders Egede;

    2015-01-01

    High driving voltages currently limit the commercial potential of dielectric elastomers (DEs). One method used to lower driving voltage is to increase dielectric permittivity of the elastomer. A novel silicone elastomer system with high dielectric permittivity was prepared through the synthesis of...... phase. Thus, the space between the functional groups can be varied, by using different dimethylsiloxane spacer units between the dipolar molecules. Furthermore, the degree of functionalization can be varied accurately by changing the feed of dipolar molecules. As a result, a completely tunable elastomer...

  18. Giant dielectric response and low dielectric loss in Al{sub 2}O{sub 3} grafted CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Rajabtabar-Darvishi, A. [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Center for Surface and Nanoanalytics (ZONA), Johannes Kepler University, Altenberger Straße 69, 4040 Linz (Austria); Bayati, R., E-mail: reza.bayati@intel.com, E-mail: mbayati@ncsu.edu, E-mail: wdfei@hit.edu.cn [Intel Corporation, IMO-RA, RA2, Hillsboro, Oregon 97124 (United States); Sheikhnejad-Bishe, O. [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Wang, L. D.; Li, W. L.; Sheng, J.; Fei, W. D., E-mail: reza.bayati@intel.com, E-mail: mbayati@ncsu.edu, E-mail: wdfei@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-03-07

    This study sheds light on the effect of alumina on dielectric constant and dielectric loss of novel CaCu{sub 3}Ti{sub 4}O{sub 12} composite ceramics. Alumina, at several concentrations, was deposited on the surface of CaCu{sub 3}Ti{sub 4}O{sub 12} particles via sol-gel technique. The dielectric constant significantly increased for all frequencies and the dielectric loss substantially decreased for low and intermediate frequencies. These observations were attributed to the change in characteristics of grains and grain boundaries. It was found that the insulating properties of the grain boundaries are improved following the addition of Al{sub 2}O{sub 3}. The relative density of CaCu{sub 3}Ti{sub 4}O{sub 12}/Al{sub 2}O{sub 3} composite ceramics decreased compared to the pure CaCu{sub 3}Ti{sub 4}O{sub 12} and the grain size was greatly changed with the alumina content affecting the dielectric properties. With the addition of alumina into CaCu{sub 3}Ti{sub 4}O{sub 12}, tighter interfaces formed. The 6%- and 10%-alumina ceramics showed the minimum dielectric loss and the maximum dielectric constant, respectively. Both the dielectric constant and loss tangent decreased in the 20%-alumina ceramic due to the formation of CuO secondary phase. It was revealed that Al serves as an electron acceptor decreasing the electron concentration, if Al{sup 3+} ions substitute for Ti{sup 4+} ions, and as an electron donor increasing the electron concentration, if Al{sup 3+} ions substitute for Ca{sup 2+} ions. We established a processing-microstructure-properties paradigm which opens new avenues for novel applications of CaCu{sub 3}Ti{sub 4}O{sub 12}/Al{sub 2}O{sub 3} composite ceramics.

  19. Affect Regulation

    DEFF Research Database (Denmark)

    Pedersen, Signe Holm; Poulsen, Stig Bernt; Lunn, Susanne

    2014-01-01

    Gergely and colleagues’ state that their Social Biofeedback Theory of Parental Affect Mirroring” can be seen as a kind of operationalization of the classical psychoanalytic concepts of holding, containing and mirroring. This article examines to what extent the social biofeedback theory of parenta...

  20. Solid solution trends that impact electrical design of submicron layers in dielectric capacitors

    Science.gov (United States)

    Levi, Roni D.

    It is predictable that future thin layer multilayer dielectrics and thin films embedded capacitors will require higher field and higher reliability performance. This thesis explores the fundamental factors that would limit the high field and reliability performance in thin layer dielectrics based on BaTiO3. Those factors have different origins: On one side, the nature of the metal-dielectric interface was shown to affect the high field dielectric properties of capacitive structures. In addition to that, the intrinsic bulk properties of BaTiO3 based solid solutions affect the high field properties of thin dielectric layers depending on composition and annealing conditions. Both effects were investigated in this study. The temperature dependence of the electrical leakage current density of chemical solution deposited BaTiO3 films on high purity Ni foils was investigated as function of the underlying Ni microstructure. The electrical properties were then characterized on capacitors with and without the presence of Ni grain boundaries. When a Ni grain boundary from the substrate was present in the capacitor used during the electrical measurements, the loss tangent of the capacitor rose rapidly for dc biases exceeding ˜25kV/cm. The critical bias increases to ˜100kV/cm when no substrate grain boundaries are included in the capacitor. In addition, the capacitance-voltage curves are much more symmetric when grain boundaries are absent. This disparity in the electrical behavior was analyzed in terms of the mechanisms of charge conduction across the Ni-dielectric interface. While a reverse biased Schottky emission mechanism dominates the current in areas free of Ni grain boundaries, the Schottky barrier at the cathode is less effective when Ni grain boundaries are present due to local enhancement of the electric field. This, leads to a larger leakage current dominated by the forward biased Schottky barrier at the anode. In addition to the interface influence, the

  1. Influence of stacking morphology and edge nitrogen doping on the dielectric performance of graphene-polymer nanocomposites

    KAUST Repository

    Almadhoun, Mahmoud N.

    2014-05-13

    We demonstrate that functional groups obtained by varying the preparation route of reduced graphene oxide (rGO) highly influence filler morphology and the overall dielectric performance of rGO-relaxor ferroelectric polymer nanocomposite. Specifically, we show that nitrogen-doping by hydrazine along the edges of reduced graphene oxide embedded in poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) results in a dielectric permittivity above 10 000 while maintaining a dielectric loss below 2. This is one of the best-reported dielectric constant/dielectric loss performance values. In contrast, rGO produced by the hydrothermal reduction route shows a much lower enhancement, reaching a maximum dielectric permittivity of 900. Furthermore, functional derivatives present in rGO are found to strongly affect the quality of dispersion and the resultant percolation threshold at low loading levels. However, high leakage currents and lowered breakdown voltages offset the advantages of increased capacitance in these ultrahigh-k systems, resulting in no significant improvement in stored energy density. © 2014 American Chemical Society.

  2. Effects of La2O3/ZnO additives on microstructure and microwave dielectric properties of Zr0.8Sn0.2TiO4 ceramics

    International Nuclear Information System (INIS)

    Dielectric ceramics of Zr0.8Sn0.2TiO4 containing La2O3 and ZnO as sintering aids were prepared and investigating for microstructure and microwave dielectric properties. Low-level doping with La2O3 and ZnO (up to 0.30 wt%) is good for densification and dielectric properties. These additives do not affect the dielectric constant and the temperature coefficient. Dielectric losses increase significantly at additive levels higher than 0.15 wt%. The combined additives La2O3 and ZnO act as grain growth enhancers. With 0.15 wt% additives, a ceramic having a dielectric constant, a quality factor, and a temperature coefficient of frequency at 4.2 GHz of 37.6, 12,800 and -2.9 ppm/C, respectively, was obtained. The quality factor was considerably improved by prolonged sintering

  3. A Review on Conduction Mechanisms in Dielectric Films

    OpenAIRE

    Fu-Chien Chiu

    2014-01-01

    The conduction mechanisms in dielectric films are crucial to the successful applications of dielectric materials. There are two types of conduction mechanisms in dielectric films, that is, electrode-limited conduction mechanism and bulk-limited conduction mechanism. The electrode-limited conduction mechanism depends on the electrical properties at the electrode-dielectric interface. Based on this type of conduction mechanism, the physical properties of the barrier height at the electrode-diel...

  4. Magnetically controlled permeability membranes

    KAUST Repository

    Kosel, Jurgen

    2013-10-31

    A bioactive material delivery system can include a thermoresponsive polymer membrane and nanowires distributed within the thermoresponsive polymer membrane. Magnetic activation of a thermoresponsive polymer membrane can take place via altering the magnetization or dimensions of nanowires dispersed or ordered within the membrane matrix.

  5. Compositional asynchronous membrane systems

    Institute of Scientific and Technical Information of China (English)

    Cosmin Bonchis; Cornel Izbasa; Gabriel Ciobanu

    2007-01-01

    This paper presents an algorithmic way of building complex membrane systems by coupling elementary membranes. Its application seems particularly valuable in the case of asynchronous membrane systems, since the resulting membrane system remains asynchronous. The composition method is based on a handshake mechanism implemented by using antiport rules and promoters.

  6. Composite sensor membrane

    Science.gov (United States)

    Majumdar, Arun; Satyanarayana, Srinath; Yue, Min

    2008-03-18

    A sensor may include a membrane to deflect in response to a change in surface stress, where a layer on the membrane is to couple one or more probe molecules with the membrane. The membrane may deflect when a target molecule reacts with one or more probe molecules.

  7. Prediction of Physical Properties of Nanofiltration Membranes for Neutral and Charged Solutes

    Science.gov (United States)

    Two commercial nanofiltration (NF) membranes viz., NF 300 MWCO and NF 250 MWCO were used for neutral and charged solute species viz., glucose, sodium chloride and magnesium chloride to investigate their rejection rates using Donnan steric pore model (DSPM) and DSPM-dielectric exc...

  8. Modeling Argon Plasma Excimer Characteristics near a Dielectric Surface in Miniaturized Volumes

    Science.gov (United States)

    Farahat, Ashraf; Ramadan, Emad

    2014-10-01

    We computationally model plasma -neutral gas dynamics in a miniaturized microthruster encloses Ar and contains a dielectric material sandwiched between two metal plates using a two dimensional plasma model. Spatial and temporal plasma properties are investigated by solving the Poisson equation with the conservation equations of charged and excited neutral plasma species. We find the microthruster properties to depend on small changes in the secondary electron emission coefficient that could result from dielectric erosion and aging. The changes also affect the electrohydrodynamic force produced when we use the microthruster to generate thrust for small spacecrafts. The electrohydrodynamic force is calculated and found to be significant in the sheath area near the dielectric layer and is found to affect gas flow dynamics including the Ar excimer formation and density. The plasma-neutral gas momentum exchange is significant in affecting gas flow dynamics and in the formation of excimer species in addition to affecting the UV and visible emission characteristics of the device. The authors would like to acknowledge the support provided by the Deanship of Scientific Research (DSR) at the King Fahd University of Petroleum & Minerals (KFUPM) for funding this work through Project No. IN111026.

  9. Variational approach for electrolyte solutions: From dielectric interfaces to charged nanopores

    Science.gov (United States)

    Buyukdagli, Sahin; Manghi, Manoel; Palmeri, John

    2010-04-01

    A variational theory is developed to study electrolyte solutions, composed of interacting pointlike ions in a solvent, in the presence of dielectric discontinuities and charges at the boundaries. Three important and nonlinear electrostatic effects induced by these interfaces are taken into account: surface charge induced electrostatic field, solvation energies due to the ionic cloud, and image-charge repulsion. Our variational equations thus go beyond the mean-field theory, or weak coupling limit, where thermal fluctuations overcome electrostatic correlations, and allows one to reach the opposite strong coupling limit, where electrostatic interactions induced by interfaces dominate. The influence of salt concentration, ion valency, dielectric jumps, and surface charge is studied in two geometries. (i) A single neutral dielectric interface (e.g., air-water or electrolyte-membrane) with an asymmetric electrolyte. A charge separation and thus an electrostatic field get established due to the different image-charge repulsions for coions and counterions. Both charge distributions and surface tension are computed and compared to previous approximate calculations. For symmetric electrolyte solutions close to a charged surface, two zones are characterized. In the first one, in contact with the surface and with size proportional to the logarithm of the coupling parameter, strong image forces and strong coupling impose a total ion exclusion, while in the second zone the mean-field approach applies. (ii) A symmetric electrolyte confined between two dielectric interfaces as a simple model of ion rejection from nanopores in membranes. The competition between image-charge repulsion and attraction of counterions by the membrane charge is studied. For small surface charge, the counterion partition coefficient decreases with increasing pore size up to a critical pore size, contrary to neutral membranes. For larger pore sizes, the whole system behaves like a neutral pore. For strong

  10. Genetic programming as an analytical tool for non-linear dielectric spectroscopy.

    Science.gov (United States)

    Woodward, A M; Gilbert, R J; Kell, D B

    1999-05-01

    By modelling the non-linear effects of membranous enzymes on an applied oscillating electromagnetic field using supervised multivariate analysis methods, Non-Linear Dielectric Spectroscopy (NLDS) has previously been shown to produce quantitative information that is indicative of the metabolic state of various organisms. The use of Genetic Programming (GP) for the multivariate analysis of NLDS data recorded from yeast fermentations is discussed, and GPs are compared with previous results using Partial Least Squares (PLS) and Artificial Neural Nets (NN). GP considerably outperforms these methods, both in terms of the precision of the predictions and their interpretability. PMID:10379559

  11. Photoelectric metal, dielectric, semiconductor (MDP) instruments. Fotoelektricheskiye MDP-pribory

    Energy Technology Data Exchange (ETDEWEB)

    Zuyev, V.A.; Popov, V.G.

    1983-01-01

    The basic patterns in photoelectrical phenomena in metal dielectric semiconductor structures are examined. The promise is noted for the use of metal dielectric semiconductor structures as the elementary base for electrooptics and as solar energy converters. The physical bases are presented of different metal dielectric semiconductor photoconverters: photoresistors, photodiodes and photoelements, photovaricaps, phototransistors and systems for recording optical information.

  12. Effects of protein crowding on membrane systems.

    Science.gov (United States)

    Guigas, Gernot; Weiss, Matthias

    2016-10-01

    Cellular membranes are typically decorated with a plethora of embedded and adsorbed macromolecules, e.g. proteins, that participate in numerous vital processes. With typical surface densities of 30,000 proteins per μm(2) cellular membranes are indeed crowded places that leave only few nanometers of private space for individual proteins. Here, we review recent advances in our understanding of protein crowding in membrane systems. We first give a brief overview on state-of-the-art approaches in experiment and simulation that are frequently used to study crowded membranes. After that, we review how crowding can affect diffusive transport of proteins and lipids in membrane systems. Next, we discuss lipid and protein sorting in crowded membrane systems, including effects like protein cluster formation, phase segregation, and lipid droplet formation. Subsequently, we highlight recent progress in uncovering crowding-induced conformational changes of membranes, e.g. membrane budding and vesicle formation. Finally, we give a short outlook on potential future developments in the field of crowded membrane systems. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26724385

  13. Affective Urbanism

    DEFF Research Database (Denmark)

    Samson, Kristine

    , experience and consumption are all strategic design tools applied by planners and architects. Whereas urban design in former modernist planning served merely functional or political means, urban design has increasingly become an aesthetical mediator of ideologies embedded in the urban field of life forces...... capitalism not only changes urban life and its means of production, it specifically influences the way the city is designed and how it unfolds as events (Anderson & Harrison 2010) and affective, emotional production (Pile 2009). Through examples of urban design and events in the Carlsberg City in Copenhagen...... and The High Line in Chelsea, New York, the paper sets out to define and question these affective modes of production. Whether these productions are socio-material practices consisting of ludic designs (Stevens 2007), temporary architecture or art installations or evental practices consisting of...

  14. Coupling of phonon-polariton modes at dielectric-dielectric interfaces by the ATR technique

    Science.gov (United States)

    Cocoletzi, G. H.; Olvera Hernández, J.; Martínez Montes, G.

    1989-08-01

    We report the calculated ATR dispersion relation of the interface phonon-polariton modes in the prism-dielectric-dielectric configuration. Comparison of electromagnetic dispersion relations (EMDR) with the ATR dispersion relations are presented for three different interfaces: I) GaAs/GaP, II) CdF2/CaF2 and III) CaF2/GaP in two propagation windows, using the Otto and Kretschmann geometries for p-polarized light. We have studied the three cases using angle and frequency scans for each window and geometry. The results indicate that it is possible to excite and detect phonon-polariton modes at the dielectric-dielectric interface.

  15. All-dielectric left-handed metamaterial based on dielectric resonator: design, simulation and experiment

    International Nuclear Information System (INIS)

    Dipoles with Lorentz-type resonant electromagnetic responses can realise negative effective parameters in their negative resonant region. The electric dipole and magnetic dipole can realise, respectively, negative permittivity and negative permeability, so both the field distribution forms of electric and magnetic dipoles are fundamentals in designing left-handed metamaterial. Based on this principle, this paper studies the field distribution in high-permittivity dielectric materials. The field distributions at different resonant modes are analysed based on the dielectric resonator theory. The origination and influence factors of the electric and magnetic dipoles are confirmed. Numerical simulations indicate that by combining dielectric cubes with different sizes, the electric resonance frequency and magnetic resonance frequency can be superposed. Finally, experiments are carried out to verify the feasibility of all-dielectric left-handed metamaterial composed by this means. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  16. Dielectric elastomers, with very high dielectric permittivity, based on silicone and ionic interpenetrating networks

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren;

    2015-01-01

    permittivity and the Young's modulus of the elastomer. One system that potentially achieves this involves interpenetrating polymer networks (IPNs), based on commercial silicone elastomers and ionic networks from amino- and carboxylic acid-functional silicones. The applicability of these materials as DEs is...... demonstrated herein, and a number of many and important parameters, such as dielectric permittivity/loss, viscoelastic properties and dielectric breakdown strength, are investigated. Ionic and silicone elastomer IPNs are promising prospects for dielectric elastomer actuators, since very high permittivities are...... obtained while dielectric breakdown strength and Young's modulus are not compromised. These good overall properties stem from the softening effect and very high permittivity of ionic networks – as high as ε′ = 7500 at 0.1 Hz – while the silicone elastomer part of the IPN provides mechanical integrity as...

  17. A self-similarity model for dielectric constant of porous ultra low-k dielectrics

    International Nuclear Information System (INIS)

    A self-similarity model applying the Sierpinski carpet approximation for the effective dielectric constant of nanoporous low-k dielectrics is proposed based on the statistically self-similar characteristics of pore size distributions in the medium and on the 'mixture rule' technique. The proposed model for the dielectric constant is expressed as a function of porosity (related to stage n of Sierpinski carpet) and the dielectric coefficient of components of the medium. The model predictions are compared with the existing experimental data and with other model predictions, and good agreement is obtained between the present model predictions and the experimental data. The proposed technique may have the potential of analysing other properties such as thermal conductivity and Young's modulus

  18. All-dielectric left-handed metamaterial based on dielectric resonator: design, simulation and experiment

    Institute of Scientific and Technical Information of China (English)

    Yang Yi-Ming; Wang Jia-Fu; Xia Song; Bai Peng; Li Zhe; Wang Jun; Xu Zhuo; Qu Shao-Bo

    2011-01-01

    Dipoles with Lorentz-type resonant electromagnetic responses can realise negative effective parameters in their negative resonant region. The electric dipole and magnetic dipole can realise, respectively, negative permittivity and negative permeability, so both the field distribution forms of electric and magnetic dipoles are fundamentals in designing left-handed metamaterial. Based on this principle, this paper studies the field distribution in high-permittivity dielectric materials. The field distributions at different resonant modes are analysed based on the dielectric resonator theory. The origination and influence factors of the electric and magnetic dipoles are confirmed. Numerical simulations indicate that by combining dielectric cubes with different sizes, the electric resonance frequency and magnetic resonance frequency can be superposed. Finally, experiments are carried out to verify the feasibility of all-dielectric left-handed metamaterial composed by this means.

  19. Effect of lipid head group interactions on membrane properties and membrane-induced cationic β-hairpin folding.

    Science.gov (United States)

    Ganesan, Sai J; Xu, Hongcheng; Matysiak, Silvina

    2016-07-21

    Stages in POPS membrane induced SVS-1 folding. One key characteristic of mIFs is the dielectric gradient and subsequently, electrostatic potential that arises from dipolar interactions in the head group region. In this work, we present a coarse-grained (CG) model for anionic and zwitterionic lipids that accounts for dipolar intricacies in the head group region. Prior work on adding dipolar interactions in a coarse grained (CG) model for peptides enabled us to achieve α/β secondary structure content de novo, without any added bias. We have now extended this idea to lipids. To mimic dipolar interactions, two dummy particles with opposite charges are added to CG polar beads. These two dummy charges represent a fluctuating dipole that introduces structural polarization into the head group region. We have used POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and POPS (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine) as our model lipids. We characterize structural, dynamic, and dielectric properties of our CG bilayer, along with the effect of monovalent ions. We observe head group dipoles to play a significant role in membrane dielectric gradient and lipid clustering induced by dipole-dipole interactions in POPS lipids. In addition, we studied membrane-induced peptide folding of a cationic antimicrobial peptide with anticancer activity, SVS-1. We find that membrane-induced peptide folding is driven by both (a) cooperativity in peptide self-interaction and (b) cooperativity in membrane-peptide interaction. In particular, dipolar interactions between the peptide backbone and lipid head groups contribute to stabilizing folded conformations. PMID:27165814

  20. Development of dielectric window to conductor assembly

    Energy Technology Data Exchange (ETDEWEB)

    Heikinheimo, L.; Nuutinen, S.; Taehtinen, S. [VTT Manufacturing Technology, Espoo (Finland). Materials and Structural Integrity

    1998-12-31

    The report summarises the work done by Association Euratom-Tekes in developing manufacturing procedures for vacuum tight ceramic to metal joints and in manufacturing full scale components for the ICRF vacuum window construction. The development started at VTT Manufacturing Technology in 1996 under the Task T238.2 and continued in 1997 under the Underlying Technology tasks. In the design of the components, the following issues were addressed and resolved: (1) The choice of dielectric material; The choice is made as the best compromise among nuclear, mechanical, and thermal properties, but in due consideration of material availability, fabrication issues and response to cyclic loads, (2) Layout and detailed design. The shape of the dielectric window is optimized to minimize electric fields in the dielectric materials; The optimised field distribution is computed in a 2D geometry; The design includes thermal calculation and the cooling layout and includes provision for remote handling replacement in one block, (3) Metal/dielectric joining. The joining technology is selected and justified. Joining tests on material selections to verify the applicability has been done, the validation of the design pre-prototype tests have been carried out selectively. The steps for the manufacture of these full scale components are described in the report with the appropriate concluding remarks and suggestions for the further actions. (orig.)

  1. DIELECTRIC RESEARCH OF POLYISOPRENE MODIFIED BY CARBAMIDE

    OpenAIRE

    Острогруд, А.Ю.

    2012-01-01

    Conducted dielectric research of polyisoprene modification by polyacrylamide in the frequency range 1-100 kHz have shown the existence of increase or decrease in molecular mobility groups of atoms and cross-site segments of the mesh polyisoprene through the displacement of existing relaxation processes in the direction of high or low frequencies at various contents of polyacrylamide.

  2. Nonlinear polariton waves in dielectric medium

    CERN Document Server

    Dzedolik, Igor V

    2012-01-01

    We theoretically investigate the properties of phonon-polariton inhomogeneous harmonic wave, cnoidal wave and spatial soliton propagating in boundless dielectric medium and compute the shape of nonlinear vector polariton wave. We obtain analytically the envelopes of linearly polarized nonlinear polariton waves in the self-focusing and self-defocusing media.

  3. Bandwidth Enhancement Techniques of Dielectric Resonator Antenna

    Directory of Open Access Journals (Sweden)

    ARCHANA SHARMA

    2011-07-01

    Full Text Available The paper briefly reviews the historical background of dielectric resonator antenna and its bandwidth enhancement techniques. The main focus is on a compact DRA that can offer broad band operation. It has been illustrated that dual resonance and multi resonance operation can be much effective to give wide band characteristics of DRA.

  4. Dielectric anomaly in coupled rotor systems

    OpenAIRE

    Shima, Hiroyuki; Nakayama, Tsuneyoshi

    2004-01-01

    The correlated dynamics of coupled quantum rotors carrying electric dipole moment is theoretically investigated. The energy spectra of coupled rotors as a function of dipolar interaction energy is analytically solved. The calculated dielectric susceptibilities of the system show the peculiar temperature dependence different from that of isolated rotors.

  5. Dielectric anomaly in coupled rotor systems

    OpenAIRE

    Shima, Hiroyuki; Nakayama, Tsuneyoshi

    2004-01-01

    The correlated dynamics of coupled quantum rotors carrying electric dipole moment is theoretically investigated. The energy spectra of coupled rotors as a function of dipolar interaction energy are analytically solved. The calculated dielectric susceptibilities of the system show a peculiar temperature dependence different from that of isolated rotors.

  6. DIELECTRIC WAKE FIELD RESONATOR ACCELERATOR MODULE

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L.

    2013-11-06

    Results are presented from experiments, and numerical analysis of wake fields set up by electron bunches passing through a cylindrical or rectangular dielectric-lined structure. These bunches excite many TM-modes, with Ez components of the wake fields sharply localized on the axis of the structure periodically behind the bunches. The experiment with the cylindrical structure, carried out at ATF Brookhaven National Laboratory, used up to three 50 MeV bunches spaced by one wake field period (21 cm) to study the superposition of wake fields by measuring the energy loss of each bunch after it passed through the 53-cm long dielectric element. The millimeter-wave spectrum of radiation excited by the passage of bunches is also studied. Numerical analysis was aimed not only to simulate the behavior of our device, but in general to predict dielectric wake field accelerator performance. It is shown that one needs to match the radius of the cylindrical dielectric channel with the bunch longitudinal rms-length to achieve optimal performance.

  7. Near-field compact dielectric optics

    Science.gov (United States)

    Feuermann, Daniel; Gordon, Jeffrey M.; Ng, Tuck Wah

    2006-08-01

    Aplanatic optics crafted from transparent dielectrics can approach the etendue limit for radiative transfer in pragmatic near-field systems. Illustrations are presented for the more demanding realm of high numerical aperture (NA) at the source and/or target. These light couplers can alleviate difficulties in aligning system components, and can achieve the fundamental compactness limit for optical devices that satisfy Fermat's principle.

  8. Dielectric Properties of Water Under Extreme Conditions

    Science.gov (United States)

    Pan, Ding

    2014-03-01

    Water is a major component of fluids in the Earth's mantle, where its properties are substantially different from those at ambient conditions. At the pressures and temperatures of the mantle, experiments on aqueous fluids are challenging, and several fundamental properties of water are poorly known; e.g., its dielectric constant has not been measured. This lack of knowledge of water dielectric properties has greatly limited our ability to model water-rock interactions and, in general, our understanding of aqueous fluids below the Earth's crust. Using ab initio molecular dynamics, we computed the dielectric constant of water under the conditions of the Earth's upper mantle, and we predicted the solubility products of carbonate minerals. We found that MgCO3 (magnesite)--insoluble in water under ambient conditions--becomes at least slightly soluble at the bottom of the upper mantle, suggesting that water may transport significant quantities of oxidized carbon. We also computed the electronic dielectric constant of water as a function of pressure and we found that, contrary to expectations based on widely used simple models, both the refractive index and the electronic band gap of water increase under pressure. The work is supported by DOE-CMCSN under Grant DE-SC0005180 and by the Sloan Foundation through the Deep Carbon Observatory.

  9. Partial discharges and bulk dielectric field enhancement

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Johansson, Torben

    A consequence of partial discharge activity within a gaseous void is the production of a field enhancement in the solid dielectric in the proximity of the void. This situation arises due to the charge created by the partial discharges accumulating at the void wall. The influence of the spatial...

  10. Actuation response of polyacrylate dielectric elastomers

    DEFF Research Database (Denmark)

    Kofod, G.; Kornbluh, R.; Pelrine, R.;

    2001-01-01

    Polyacrylate dielectric elastomers have yielded extremely large strain and elastic energy density suggesting that they are useful for many actuator applications. A thorough understanding of the physics underlying the mechanism of the observed response to an electric field can help develop improved...

  11. Dielectric Elastomer Based "Grippers" for Soft Robotics.

    Science.gov (United States)

    Shian, Samuel; Bertoldi, Katia; Clarke, David R

    2015-11-18

    The use of few stiff fibers to control the deformation of dielectric elastomer actuators, in particular to break the symmetry of equi-biaxial lateral strain in the absence of prestretch, is demonstrated. Actuators with patterned fibers are shown to evolve into unique shapes upon electrical actuation, enabling novel designs of gripping actuators for soft robotics. PMID:26418227

  12. Casimir effect in dielectrics: Bulk energy contribution

    International Nuclear Information System (INIS)

    In a recent series of papers, Schwinger discussed a process that he called the dynamical Casimir effect. The key essence of this effect is the change in zero-point energy associated with any change in a dielectric medium. (In particular, if the change in the dielectric medium is taken to be the growth or collapse of a bubble, this effect may have relevance to sonoluminescence.) The kernel of Schwinger close-quote s result is that the change in Casimir energy is proportional to the change in the volume of the dielectric, plus finite-volume corrections. Other papers have called into question this result, claiming that the volume term should actually be discarded, and that the dominant term remaining is proportional to the surface area of the dielectric. In this paper, which is an expansion of an earlier Letter on the same topic, we present a careful and critical review of the relevant analyses. We find that the Casimir energy, defined as the change in zero-point energy due to a change in the medium, has at leading order a bulk volume dependence. This is in full agreement with Schwinger close-quote s result, once the correct physical question is asked. We have nothing new to say about sonoluminescence itself. copyright 1997 The American Physical Society

  13. Dielectric tensor of strongly coupled plasmas

    International Nuclear Information System (INIS)

    Complex conductivity and dielectric permeability tensors of strongly coupled plasmas are studied and constructed on the basis of exact relations and sum rules. Both Coulomb and magnetic correlation are taken into account. The electromagnetic mode dispersion law is studied. The magnetostatic properties of a system of charged particles are investigated in detail. 26 refs

  14. 7th International Symposium on Gaseous Dielectrics

    CERN Document Server

    James, David

    1994-01-01

    The Seventh International Symposium on Gaseous Dielectrics was held in Knoxville, Tennessee, U. S. A. , on April 24-28, 1994. The symposium continued the interdisciplinary character and comprehensive approach of the preceding six symposia. Gaseous DielecIries VII is a detailed record of the symposium proceedings. It covers recent advances and developments in a wide range of basic, applied and industrial areas of gaseous dielectrics. It is hoped that Gaseous DielecIries VII will aid future research and development in, and encourage wider industrial use of, gaseous dielectrics. The Organizing Committee of the Seventh International Symposium on Gaseous Dielectrics consisted of G. Addis (U. S. A. ), L. G. Christophorou (U. S. A. ), F. Y. Chu (Canada), A. H. Cookson (U. S. A. ), O. Farish (U. K. ), I. Gallimberti (Italy) , A. Garscadden (U. S. A. ), D. R. James (U. S. A. ), E. Marode (France), T. Nitta (Japan), W. Pfeiffer (Germany), Y. Qiu (China), I. Sauers (U. S. A. ), R. J. Van Brunt (U. S. A. ), and W. Zaengl...

  15. Casimir effect in dielectrics Bulk Energy Contribution

    CERN Document Server

    Carlson, C E; Pérez-Mercader, J; Visser, M; Visser, Matt

    1997-01-01

    In a recent series of papers, Schwinger discussed a process that he called the Dynamical Casimir Effect. The key essence of this effect is the change in zero-point energy associated with any change in a dielectric medium. (In particular, if the change in the dielectric medium is taken to be the growth or collapse of a bubble, this effect may have relevance to sonoluminescence.) The kernel of Schwinger's result is that the change in Casimir energy is proportional to the change in volume of the dielectric, plus finite-volume corrections. Other papers have called into question this result, claiming that the volume term should actually be discarded, and that the dominant term remaining is proportional to the surface area of the dielectric. In this communication, which is an expansion of an earlier letter on the same topic, we present a careful and critical review of the relevant analyses. We find that the Casimir energy, defined as the change in zero-point energy due to a change in the medium, has at leading orde...

  16. The Electrical Breakdown of Thin Dielectric Elastomers

    DEFF Research Database (Denmark)

    Zakaria, Shamsul Bin; Morshuis, Peter H. F.; Yahia, Benslimane Mohamed;

    2014-01-01

    Dielectric elastomers are being developed for use in actuators, sensors and generators to be used in various applications, such as artificial eye lids, pressure sensors and human motion energy generators. In order to obtain maximum efficiency, the devices are operated at high electrical fields...

  17. Optimization of Organotin Polymers for Dielectric Applications.

    Science.gov (United States)

    Treich, Gregory M; Nasreen, Shamima; Mannodi Kanakkithodi, Arun; Ma, Rui; Tefferi, Mattewos; Flynn, James; Cao, Yang; Ramprasad, Rampi; Sotzing, Gregory A

    2016-08-24

    Recently, there has been a growing interest in developing wide band gap dielectric materials as the next generation insulators for capacitors, photovoltaic devices, and transistors. Organotin polyesters have shown promise as high dielectric constant, low loss, and high band gap materials. Guided by first-principles calculations from density functional theory (DFT), in line with the emerging codesign concept, the polymer poly(dimethyltin 3,3-dimethylglutarate), p(DMTDMG), was identified as a promising candidate for dielectric applications. Blends and copolymers of poly(dimethyltin suberate), p(DMTSub), and p(DMTDMG) were compared using increasing amounts of p(DMTSub) from 10% to 50% to find a balance between electronic properties and film morphology. DFT calculations were used to gain further insight into the structural and electronic differences between p(DMTSub) and p(DMTDMG). Both blend and copolymer systems showed improved results over the homopolymers with the films having dielectric constants of 6.8 and 6.7 at 10 kHz with losses of 1% and 2% for the blend and copolymer systems, respectively. The energy density of the film measured as a D-E hysteresis loop was 6 J/cc for the copolymer, showing an improvement compared to 4 J/cc for the blend. This improvement is hypothesized to come from a more uniform distribution of diacid repeat units in the copolymer compared to the blend, leading toward improved film quality and subsequently higher energy density. PMID:27467895

  18. Dielectric barrier discharge source for supersonic beams

    Energy Technology Data Exchange (ETDEWEB)

    Luria, K.; Lavie, N.; Even, U. [Sackler School of Chemistry, Tel Aviv University, Tel Aviv 69978 (Israel)

    2009-10-15

    We present a new excitation source for pulsed supersonic beams. The excitation is based on dielectric barrier discharge in the beam. It produces cold beams of metastable atoms, dissociated neutral atoms from molecular precursors, and both positive and negative ions with high efficiency and reliability.

  19. Large scale processing of dielectric electroactive polymers

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu

    Efficient processing techniques are vital to the success of any manufacturing industry. The processing techniques determine the quality of the products and thus to a large extent the performance and reliability of the products that are manufactured. The dielectric electroactive polymer (DEAP...

  20. Chains of coupled square dielectric optical microcavities

    NARCIS (Netherlands)

    Hammer, Manfred

    2009-01-01

    Chains of coupled square dielectric cavities are investigated in a 2-D setting, by means of a quasi-analytical eigenmode expansion method. Resonant transfer of optical power can be achieved along quite arbitrary, moderately long rectangular paths (up to 9 coupled cavities are considered), even with

  1. Photon Momentum in Linear Dielectric Media

    CERN Document Server

    Crenshaw, Michael E

    2015-01-01

    According to the scientific literature, the momentum of a photon in a simple linear dielectric is either $\\hbar\\omega/(nc)$ or $n\\hbar\\omega/c$ with a unit vector ${\\bf \\hat e}_k$ in the direction of propagation. These momentums are typically used to argue the century-old Abraham--Minkowski controversy in which the momentum density of the electromagnetic field in a dielectric is either the Abraham momentum density, ${\\bf g}_A={\\bf E}\\times{\\bf H}/c$, or the Minkowski momentum density, ${\\bf g}_M={\\bf D}\\times{\\bf B}/c$. The elementary optical excitations, photons, are typically known as polaritions in the particular case of light traveling in a dielectric medium. Applying the relativistic energy formula, we find that the total momentum that is attributable to a polariton in a dielectric is $\\hbar\\omega{\\bf \\hat e}_k/c$ corresponding to a total momentum density ${\\bf g}_T=n{\\bf E}\\times{\\bf B}/c$.

  2. Vectorial analysis of dielectric photonic crystal VCSEL

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    A new vertical-cavity surface-emitting laser structure employing a dielectric photonic crystal mirror has been suggested and been numerically investigated. The new structure has a smaller threshold gain, a moderate strength of single-transverse-mode operation, a high quality of emission beam free...

  3. Spontaneous emission from active dielectric microstructures

    DEFF Research Database (Denmark)

    Søndergaard, Thomas; Tromborg, Bjarne

    2001-01-01

    engineered due to the dependence of the emission rate on the location and polarisation of the emitters in the structure. This paper addresses the methods of quantum electrodynamics of dielectric media which enable calculation of the local rate of spontaneous emission in active microstructures....

  4. Characterization of Dielectric Electroactive Polymer transducers

    DEFF Research Database (Denmark)

    Nielsen, Dennis; Møller, Martin B.; Sarban, Rahimullah;

    2014-01-01

    This paper analysis the small-signal model of the Dielectric Electro Active Polymer (DEAP) transducer. The DEAP transducer have been proposed as an alternative to the electrodynamic transducer in sound reproduction systems. In order to understand how the DEAP transducer works, and provide...

  5. Modelling of dielectric barrier discharge plasma actuators with thick electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Hoskinson, A R; Hershkowitz, N, E-mail: hershkowitz@engr.wisc.edu [Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2011-03-02

    We have developed a new two-dimensional fluid simulation to model the plasma dynamics in surface dielectric barrier discharges operating in air. Single-barrier (one electrode insulated) and double-barrier (both electrodes insulated) discharges have been observed to generate a force in the nearby air, making them potentially useful as aerodynamic actuators. Many previous simulations of such discharges have modelled the electrodes as thin strips. We instead consider plasma actuators including cylindrical electrodes of various sizes. In single-barrier actuators, the size of the exposed electrode qualitatively affects the discharge dynamics, particularly with a negative-going applied voltage. For both geometries, the simulations predict the formation of plasma structures similar to those imaged in previous experiments. Experimentally observed increases in forces for actuators with smaller high-voltage electrodes were only reproduced for the single-barrier geometry. Due to limitations of computational power, voltage rates of change for all simulations were higher than those used in experiments.

  6. Sintering additions as dopants in zirconium titanate microwave dielectric materials

    International Nuclear Information System (INIS)

    Many industrially important electronic ceramic components are conventionally sintered using sintering aids; aliovalent oxide additives said to help in densification at moderate temperatures. The authors report on a study of the microwave dielectric composition Zr/sub 0.8/Ti/sub 1.0/Sn/sub 0.2/O/sub 4/, sintered with and without the chemical additives La/sub 2/O/sub 3/ or ZnO (commonly used in industry), in a preliminary study to being to quantify the effects of sintering aid additions on the ionic and electronic defect concentrations which may affect transport properties and sintering behavior. A defect model is proposed in which a limited solubility of the sintering aid for dopant significantly effects final stage densification but overall grain growth is controlled through the intrinsic defect states of the solid solution

  7. New inorganic-organic proton conducting membranes based on Nafion and hydrophobic fluoroalkylated silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Di Noto, Vito [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, I-35131 Padova (PD) (Italy); Istituto di Scienze e Tecnologie Molecolari, ISTM-CNR and INSTM, Dipartimento di Scienze Chimiche, Via Marzolo 1, I-35131 Padova (PD) (Italy); Boaretto, Nicola; Negro, Enrico [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, I-35131 Padova (PD) (Italy); Pace, Giuseppe [Istituto di Scienze e Tecnologie Molecolari, ISTM-CNR and INSTM, Dipartimento di Scienze Chimiche, Via Marzolo 1, I-35131 Padova (PD) (Italy)

    2010-12-01

    In this report, a new nanofiller consisting of silica ''cores'' bearing fluoroalkyl surface functionalities is synthesized and adopted in the preparation of a series of hybrid inorganic-organic proton conducting membranes based on Nafion. The hybrid materials are obtained by a solvent-casting procedure and include between 0 and 10 wt.% of nanofiller. The resulting systems are extensively characterized by Thermogravimetry (TG), Modulated Differential Scanning Calorimetry (MDSC) and Dynamic Mechanical Analysis (DMA), showing that the hybrid materials are stable up to 240 C and that their overall thermal and mechanical properties are affected both by the polar groups on the surface of the silica ''cores'' and by the fluoroalkyl surface functionalities of the nanofiller. The electric properties of the hybrid materials are investigated by broadband dielectric spectroscopy (BDS). It is shown that proton conductivity of the materials is not compromised by the lower water uptake arising from the hydrophobic character of the nanofiller. With respect to a pristine Nafion recast membrane, the hybrid material characterized by 5 wt.% of nanofiller, [Nafion/(Si{sub 80}F){sub 0.7}], shows the highest conductivity in all the investigated temperature range (5 {<=} T {<=} 155 C). Indeed, [Nafion/(Si{sub 80}F){sub 0.7}] features the lowest water uptake and presents a conductivity of 0.083 S cm{sup -1} at 135 C. This result is consistent with the good performance of the membrane in single fuel cell tests. (author)

  8. Membrane fluids and Dirac membrane fluids

    CERN Document Server

    Ivanov, M G

    2004-01-01

    The relation between two different methods of membrane fluid description is clarified by construction of combined method. Dirac membrane field appears naturally in new approach. It provides a possibility to consider new aspects of electrodynamics-type theories with electric and magnetic sources. The membrane fluid models automatically prohibit simulatenos existence of electric and magnetic currents. Possible applications to the dark energy problem are mentioned.

  9. The Sensitivity of Dielectric and NMR Measurements to Sorption at the Solid/Water Interface

    Science.gov (United States)

    Knight, R. J.

    2011-12-01

    Measurements of the real part of the relative dielectric permittivity (dielectric constant) and the NMR relaxation time constants (T1 and T2) of water-saturated geological materials, contain information about molecular-scale processes and are used to estimate pore-scale properties. While the measurements probe different aspects of the response of a porous medium, it is well-established that the measured dielectric and NMR parameters are sensitive to the size and state of the solid/water interface. Laboratory and theoretical studies have shown the dielectric constant and NMR relaxation rates (1/T1 and 1/T2) of water-saturated geological materials to be proportional to the surface-area-to-volume ratio of the pore space. It is important to emphasize that the surface area, related to the magnitude of these measured parameters, is the water-wet surface area of a material. The fact that the sorption of chemical species (other than water) at the solid/water interface reduces the size of the water-wet surface area, raises the following question: Can dielectric and NMR measurements provide a sensitive, reliable tool for monitoring the sorption and desorption of contaminants in geological materials? Laboratory studies have explored the way in which changes in the wettability of a material affect the dielectric constant. In studies where the geological material was altered so as to be fully hydrophobic or oil-wet, a significant decrease was seen in the dielectric constant. Eliminating the solid/water interface appears to eliminate the contributions of surface processes to the dielectric response. In another study, as oil sorbed to the surfaces of water-saturated samples of sand and clay, a gradual decrease in dielectric constant was seen due to the decrease in water-wet surface area with increasing sorption. While this behavior is consistent with developed theoretical models, accurately predicting the magnitude of the effect remains a topic of research. Unlike the dielectric

  10. Analytical solutions of nonlocal Poisson dielectric models with multiple point charges inside a dielectric sphere

    Science.gov (United States)

    Xie, Dexuan; Volkmer, Hans W.; Ying, Jinyong

    2016-04-01

    The nonlocal dielectric approach has led to new models and solvers for predicting electrostatics of proteins (or other biomolecules), but how to validate and compare them remains a challenge. To promote such a study, in this paper, two typical nonlocal dielectric models are revisited. Their analytical solutions are then found in the expressions of simple series for a dielectric sphere containing any number of point charges. As a special case, the analytical solution of the corresponding Poisson dielectric model is also derived in simple series, which significantly improves the well known Kirkwood's double series expansion. Furthermore, a convolution of one nonlocal dielectric solution with a commonly used nonlocal kernel function is obtained, along with the reaction parts of these local and nonlocal solutions. To turn these new series solutions into a valuable research tool, they are programed as a free fortran software package, which can input point charge data directly from a protein data bank file. Consequently, different validation tests can be quickly done on different proteins. Finally, a test example for a protein with 488 atomic charges is reported to demonstrate the differences between the local and nonlocal models as well as the importance of using the reaction parts to develop local and nonlocal dielectric solvers.

  11. Dielectric and photo-dielectric properties of TlGaSeS crystals

    Indian Academy of Sciences (India)

    A F Qasrawi; Samah F Abu-Zaid; Salam A Ghanameh; N M Gasanly

    2014-05-01

    The room temperature, dark and photo-dielectric properties of the novel crystals TlGaSeS are investigated in the frequency, intensity and biasing voltage having ranges of ~ 1–120 MHz, 14–40 klux and 0–1 V, respectively. The crystals are observed to exhibit a dark high frequency effective dielectric constant value of ∼ 10.65 × 103 with a quality factor of ∼ 8.84 × 104 at ∼ 120 MHz. The dielectric spectra showed sharp resonance–antiresonance peaks in the frequency range of ∼ 25–250 kHz. When photoexcited, pronounced increase in the dielectric constant and in the quality factor values with increasing illumination intensity are observed. Signal amplification up to ∼ 33% with improved signal quality up to ∼ 29% is attainable via photoexcitation. On the other hand, the illuminated capacitance–voltage characteristics of the crystals reflected a downward shift in the voltage biasing and in the built-in voltage of the device that is associated with increase in the uncompensated carrier density. The increase in the dielectric constant with increasing illumination intensity is ascribed to the decrease in the crystal's resistance as a result of increased free carrier density. The light sensitivity of the crystals, the improved dielectric properties and the lower biasing voltage obtained via photoexcitation and the well-enhanced signal quality factor of the crystals make them promising candidates for optical communication systems.

  12. Effect of vacuum-ultraviolet irradiation on the dielectric constant of low-k organosilicate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, H.; Shohet, J. L. [Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Ryan, E. T. [GLOBALFOUNDRIES, Albany, New York 12203 (United States); Nishi, Y. [Stanford University, Stanford, California 94305 (United States)

    2014-11-17

    Vacuum ultraviolet (VUV) irradiation is generated during plasma processing in semiconductor fabrications, while the effect of VUV irradiation on the dielectric constant (k value) of low-k materials is still an open question. To clarify this problem, VUV photons with a range of energies were exposed on low-k organosilicate dielectrics (SiCOH) samples at room temperature. Photon energies equal to or larger than 6.0 eV were found to decrease the k value of SiCOH films. VUV photons with lower energies do not have this effect. This shows the need for thermal heating in traditional ultraviolet (UV) curing since UV light sources do not have sufficient energy to change the dielectric constant of SiCOH and additional energy is required from thermal heating. In addition, 6.2 eV photon irradiation was found to be the most effective in decreasing the dielectric constant of low-k organosilicate films. Fourier Transform Infra-red Spectroscopy shows that these 6.2 eV VUV exposures removed organic porogens. This contributes to the decrease of the dielectric constant. This information provides the range of VUV photon energies that could decrease the dielectric constant of low-k materials most effectively.

  13. Investigation of organic fouling of microfiltration membrane

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; CUI Chong-wei; MA Jun

    2005-01-01

    Because the natural organic matters (NOMs) and proteins are the principal foulants of microfiltration membranes in drinking water, the primary aim of this paper is to obtain a better understanding of the interactions between those foulants and the microfiltration membrane from a novel view of coagulation. Based on reviewed literature and our own analysis, the authors consider that the behaviors of NOMs in the fouling of microfiltration membrane are like a form of crystal growth, and we recognize that the extent of the membrane hydrophobicity plays an essential role in NOMs fouling. However, proteins' fouling is more affected by intermolecular interaction. Additionally, the effect of membrane surface chemistry is not as essential as it is in the situation of NOMs.

  14. Plasma Treatment of Industrial Landfill Leachate by Atmospheric Pressure Dielectric Barrier Discharges%Plasma Treatment of Industrial Landfill Leachate by Atmospheric Pressure Dielectric Barrier Discharges

    Institute of Scientific and Technical Information of China (English)

    赵迪; 王达成; 严贵; 马宏; 熊小京; 罗津晶; 张先徽; 刘东平; 杨思泽

    2011-01-01

    An dielectric barrier discharge (DBD) system in atmospheric pressure utilized for the treatment of industrial landfill leachate is reported. The discharge parameters, such as the operating frequency, gas flow rate, and treating duration, were found to affect significantly the removal of ammonia nitrogen (AN) in industrial landfill leachate. An increase in treating duration leads to an obvious increase in the removal efficiency of AN (up to 83%) and the leachate color changed from deep grey-black to transparent. Thus the dielectric barrier discharges in atmospheric pressure could degrade the landfill leachate effectively. Typical waveforms of both applied voltage and discharge current were also presented for analyzing the discharge processes under different discharge parameters. Optical emission spectra measurements indicate that oxidation species generated in oxygen DBD plasma play a crucial role in removing AN, oxidizing organic and inorganic substances and decolorizing the landfill leachate.

  15. Sheet Membrane Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  16. Investigation of Film Curing by Dielectric Analysis.

    Science.gov (United States)

    Guma, Noemi Candelaria

    1995-01-01

    Dielectric analysis (DEA) relies on the response of molecules to a changing electric field. Permittivity (epsilon^') is a parameter obtained from DEA, which is proportional to the amount of molecular alignment (or motion). A DEA methodology was developed to evaluate and classify the degree of cure of films, and to demonstrate the mechanism of the curing phenomenon at a molecular level. The model material employed in the study was Eudragit^circler RS30D, an aqueous-based film forming polymeric material, containing 20% acetyl tributyl citrate as plasticizer. The data showed changes in the dielectric behavior of the polymer molecules in films that were subjected to accelerated stability or improper curing conditions. These dielectric changes were also manifested as changes in the permeability characteristics of the film, which ultimately influenced the final performance of the dosage form. By monitoring the dielectric behavior of the coating material during a curing cycle, a classification of three stages of curing was developed, namely undercured, optimally cured, and overcured. The changes in dielectric properties of the film reflected the changes in molecular structure, which correlated with changes in permeability and surface morphology. Based on the data, a mechanism of improper cure was proposed, which contends that the curing phenomenon is driven by two major forces, namely: the heterogenous loss and/or redistribution of plasticizer molecules during the curing process and the development of strain in the film structure during the coating process. A mathematical equation was derived to predict the epsilon^' of film-coated beads based on the epsilon^ ' data of free films cured under the same conditions. The model is based on the premise that "equal epsilon^' denotes equal mobility" for the same material, whether as free film or applied onto a substrate. The DEA technique developed and the proposed rationale of the curing phenomenon may be useful in optimizing the

  17. Supported Pd-Au Membrane Reactor for Hydrogen Production: Membrane Preparation, Characterization and Testing.

    Science.gov (United States)

    Iulianelli, Adolfo; Alavi, Marjan; Bagnato, Giuseppe; Liguori, Simona; Wilcox, Jennifer; Rahimpour, Mohammad Reza; Eslamlouyan, Reza; Anzelmo, Bryce; Basile, Angelo

    2016-01-01

    A supported Pd-Au (Au 7wt%) membrane was produced by electroless plating deposition. Permeation tests were performed with pure gas (H₂, H₂, N₂, CO₂, CH₄) for long time operation. After around 400 h under testing, the composite Pd-Au membrane achieved steady state condition, with an H₂/N₂ ideal selectivity of around 500 at 420 °C and 50 kPa as transmembrane pressure, remaining stable up to 1100 h under operation. Afterwards, the membrane was allocated in a membrane reactor module for methane steam reforming reaction tests. As a preliminary application, at 420 °C, 300 kPa of reaction pressure, space velocity of 4100 h(-1), 40% methane conversion and 35% hydrogen recovery were reached using a commercial Ni/Al₂O₃ catalyst. Unfortunately, a severe coke deposition affected irreversibly the composite membrane, determining the loss of the hydrogen permeation characteristics of the supported Pd-Au membrane. PMID:27171067

  18. Flavonoid-membrane Interactions: A Protective Role of Flavonoids at the Membrane Surface?

    Directory of Open Access Journals (Sweden)

    Patricia I. Oteiza

    2005-01-01

    Full Text Available Flavonoids can exert beneficial health effects through multiple mechanisms. In this paper, we address the important, although not fully understood, capacity of flavonoids to interact with cell membranes. The interactions of polyphenols with bilayers include: (a the partition of the more non-polar compounds in the hydrophobic interior of the membrane, and (b the formation of hydrogen bonds between the polar head groups of lipids and the more hydrophilic flavonoids at the membrane interface. The consequences of these interactions are discussed. The induction of changes in membrane physical properties can affect the rates of membrane lipid and protein oxidation. The partition of certain flavonoids in the hydrophobic core can result in a chain breaking antioxidant activity. We suggest that interactions of polyphenols at the surface of bilayers through hydrogen bonding, can act to reduce the access of deleterious molecules (i.e. oxidants, thus protecting the structure and function of membranes.

  19. Water desalination by air-gap membrane distillation using meltblown polypropylene nanofiber membrane

    Science.gov (United States)

    Rosalam, S.; Chiam, C. K.; Widyaparamitha, S.; Chang, Y. W.; Lee, C. A.

    2016-06-01

    This paper presents a study of air gap membrane distillation (AGMD) using meltblown polypropylene (PP) nanofiber membrane to produce fresh water via desalination process. PP nanofiber membranes with the effective area 0.17 m2 are tested with NaCl solutions (0.5 - 4.0 wt.%) and seawater as the feed solutions (9400 - 64800 μS/cm) in a tubular membrane module. Results show that the flux decreases with increasing the membrane thickness from 547 to 784 μm. The flux increases with the feed flow rate and temperature difference across the membrane. The feed concentration affects the flux insignificantly. The AGMD system can reject the salts at least 96%. Water vapor permeation rate is relatively higher than solute permeation rate resulting in the conductivity value of permeate decreases when the corresponding flux increases. The AGMD system produces the fresh water (200 - 1520 μS/cm) that is suitable for drinking, fisheries or irrigation.

  20. Trends of microwave dielectric materials for antenna application

    Science.gov (United States)

    Sulong, T. A. T.; Osman, R. A. M.; Idris, M. S.

    2016-07-01

    Rapid development of a modern microwave communication system requires a high quality microwave dielectric ceramic material to be used as mobile and satellite communication. High permittivity of dielectric ceramics leads to fabrication of compact device for electronic components. Dielectric ceramics which used for microwave applications required three important parameters such as high or appropriate permittivity (ɛr), high quality factor (Q f ≥ 5000GH z) and good temperature coefficient of resonant frequency (τf). This paper review of various dielectric ceramic materials used as microwave dielectric materials and related parameters for antenna applications.

  1. Observation of Cavity QED in thick dielectric films

    Science.gov (United States)

    Sarabi, Bahman; Ramanayaka, A. N.; Gladchenko, S.; Stoutimore, M. J. A.; Khalil, M. S.; Osborn, K. D.

    2013-03-01

    Cavity QED in amorphous dielectrics is investigated by measuring five linear superconducting resonators with thick dielectric films and capacitor volumes ranging from 80 μm3 to 5000 μm3. In the smallest volume dielectrics we observe additional resonances which may be explained by CQED, despite the dielectric volume which is many orders of magnitude larger than Josephson junction barrier volumes. In addition to the volume dependence of the CQED resonances, we will report on the stability of the resonances in time and the phase noise. This research allows new fundamental studies on TLS phenomena in meso-volume amorphous dielectrics.

  2. Dielectric measurements on PWB materials at microwave frequencies

    Indian Academy of Sciences (India)

    A Tanwar; K K Gupta; P J Singh; Y K Vijay

    2006-04-01

    In quest of finding new substrate for printed wiring board (PWB) having low dielectric constant, we have made PSF/PMMA blends and evaluated the dielectric parameters at 8.92 GHz frequency and at 35°C temperature. Incorporating PMMA in PSF matrix results in reduced dielectric constant than that of pure PSF. The dielectric parameters of pure PMMA and PSF films of different thicknesses have also been obtained at microwave frequencies. We have used dielectric data at microwave frequencies as a tool to evaluate optical constants, absorption index `’ and refractive index `’. The blends of PSF/PMMA may be used as base materials for PWBs.

  3. High index of refraction films for dielectric mirrors prepared by metal-organic chemical vapor deposition

    International Nuclear Information System (INIS)

    A wide variety of metal oxides with high index of refraction can be prepared by Metal-Organic Chemical Vapor Deposition. We present some recent optical and laser damage results on oxide films prepared by MOCVD which could be used in a multilayer structure for highly reflecting (HR) dielectric mirror applications. The method of preparation affects both optical properties and laser damage threshold. 10 refs., 8 figs., 4 tabs

  4. Dielectric sample with two-layer charge distribution for space charge calibration purposes

    DEFF Research Database (Denmark)

    Holbøll, Joachim; Henriksen, Mogens; Rasmussen, C.

    2002-01-01

    In the present paper is described a dielectric test sample with two very narrow concentrations of bulk charges, achieved by two internal electrodes not affecting the acoustical properties of the sample, a fact important for optimal application of most space charge measuring systems. Space charge...... formation was investigated under different electrical conditions by means of the laser induced pressure pulse (LIPP) method and the pulsed electro-acoustic method (PEA)....

  5. Dielectric response of F--doped PbWO4 single crystal

    International Nuclear Information System (INIS)

    PbF2 doping is known to affect significantly the scintillating properties of PbWO4 single crystal, yet the nature of the extrinsic defects so induced remains unclear. In this paper, complex impedance spectroscopy was used to study the dielectric relaxation of PbF2-doped PWO crystals and provided information on its dipole relaxation and evidence for its defect complexes [2(FO2-) circle -VPb'']. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  6. Gas transmission through microporous membranes

    Science.gov (United States)

    Turel, Tacibaht

    2008-10-01

    upon passage of the gas through active and non-active membranes by which way the effect of active elements on gas transmission rates could be examined. Probabilistic and mathematical models were proposed to predict gas transmission rates of such membranes and gas permeation experiments were simulated utilizing the proposed models. Modeling results were compared to experimental data and to macrolevel gas transmission models available in literature. The results were found to be in acceptable correlation with experiments for membranes with a well-known morphology. The pressure of the system, porosity and adsorption capacity of the materials, as well as size of the gas molecules and their interaction energies between the surfaces were found to be important parameters which affect permeability.

  7. Affective Maps

    DEFF Research Database (Denmark)

    Salovaara-Moring, Inka

    Recently, in human geography there has been a considerable attention paid to retheorising maps; less as a product and more as practice. This refers to the notion that rather than reading maps as fixed representations, digital mapping is by nature a dynamic, performative, and participatory practice....... In particular, mapping environmental damage, endangered species, and human made disasters has become one of the focal point of affective knowledge production. These ‘more-than-humangeographies’ practices include notions of species, space and territory, and movement towards a new political ecology...

  8. The strength of side chain hydrogen bonds in the plasma membrane

    Science.gov (United States)

    Hristova, Kalina; Sarabipour, Sarvenaz

    2013-03-01

    There are no direct quantitative measurements of hydrogen bond strengths in membrane proteins residing in their native cellular environment. To address this knowledge gap, here we use fluorescence resonance energy transfer (FRET) to measure the impact of hydrogen bonds on the stability of a membrane protein dimer in vesicles derived from eukaryotic plasma membranes, and we compare these results to previous measurements of hydrogen bond strengths in model lipid bilayers. We demonstrate that FRET measurements of membrane protein interactions in plasma membrane vesicles have the requisite sensitivity to quantify the strength of hydrogen bonds. We find that the hydrogen bond-mediated stabilization in the plasma membrane is small, only -0.7 kcal/mole. It is the same as in model lipid bilayers, despite the different nature and dielectric properties of the two environments.

  9. Low-temperature sintering and microwave dielectric properties of (Zr,Sn)TiO4 ceramics

    International Nuclear Information System (INIS)

    Zirconium tin titanate ceramics, especially the Zr0.8Sn0.2TiO4 (ZST) ceramics, suitable for use in resonators or filters at microwave frequency, have a high Q value and a low temperature coefficient of resonant frequency. However, the sintering temperature still remained as high as 1350 deg. C. The methods including glass additions, wet chemical processing, and liquid-phase sintering aids have been used to lower the sintering temperature of ZST ceramics. Using glass additives was found to effectively lower the sintering temperature. Nevertheless, it decreased the microwave dielectric properties of ZST ceramics. The wet chemical processes, especially the coprecipitation route, offered advantages over traditional processing techniques, but often required a complicated procedure that would increase the cost and time in fabricating the ZST ceramics. In contrast, the sintering temperature of ZST ceramics with BaCuO2+CuO,CuO, or V2O5 additions could be effectively reduced without decreasing the microwave dielectric properties due to the liquid phase effects. The microwave dielectric properties of ZST ceramics were sensitive to processing conditions and microstructure features. The dielectric constants were not significantly affected by various additives while the quality factors were strongly dependent on the type and the amount of additives

  10. Dielectric properties of water and their impact on the Earth's deep carbon cycle

    Science.gov (United States)

    Pan, Ding; Spanu, Leonardo; Harrison, Brandon; Sverjensky, Dimitri; Galli, Giulia

    2013-03-01

    Knowledge of the dielectric constant of water as a function of pressure (P) and temperature (T) plays a critical role in understanding the chemistry of aqueous systems, and in particular of fluids in the Earth's mantle. By using ab initio molecular dynamics, we computed the dielectric constant of water at T = 1000 and 2000 K, between 1 and 12 GPa, under conditions of the Earth's upper mantle. By comparing our results with available experimental data and empirical models, we discuss how the changes in the molecular dipole moments and hydrogen-bond network upon compression affect the dielectric constant of the liquid. Based on the calculated dielectric constants, the solubility products of carbonate minerals were predicted. At P ~ 10 GPa and T = 1000 K, we found that MgCO3 (magnesite) is slightly soluble in water at the millimolal level, which suggests that water in the Earth's mantle has the capacity to store and transport significant quantities of oxidized carbon. Supported by Sloan/DCO (#2011-10-01) and DOE-CMSN (DE-SC0005180).

  11. Dielectric properties and conductivity of carbon nanofiber/semi-crystalline polymer composites

    International Nuclear Information System (INIS)

    The properties of semi-crystalline polymer nanocomposites are affected by the nanofillers directly and indirectly, as two phases, i.e., crystalline and amorphous, exist in the polymer. The effects of nanofillers on the two phases could be competitive. The dielectric properties and conductivity of carbon nanofibers (CNF)/semi-crystalline polymer nanocomposites are studied in this paper. CNF/polypropylene (PP) nanocomposites are prepared in experiment by melt blending. The resulting morphology and crystalline structure are characterized by means of differential scanning calorimetry, wide angle X-ray diffraction and scanning electron microscopy. The PP nanocomposite containing 5 wt.% CNF exhibits a surprisingly high dielectric constant under wide sweep frequencies attended by low dielectric loss. Its dielectric constant is >600 under lower frequency, and remains >200 at a frequency of 4000 Hz. The electrical and thermal conductivities of the nanocomposites are studied, and enhancements are seen with increased CNF content. Theoretical analyses on the physical properties are carried out by applying the existing models. Research results indicate that a common commercial plastic with good comprehensive performance, which exhibited the potential for applications in advanced electronics, was obtained by a simple industry benign technique

  12. Dielectric Properties and Characterisation of Titanium Dioxide Obtained by Different Chemistry Methods

    Directory of Open Access Journals (Sweden)

    Aleksandra Wypych

    2014-01-01

    Full Text Available We made comparison of titanium dioxide powders obtained from three syntheses including sol-gel and precipitation methods as well as using layered (tetramethylammonium titanate as a source of TiO2. The obtained precursors were subjected to step annealing at elevated temperatures to transform into rutile form. The transformation was determined by Raman measurements in each case. The resulting products were characterised using Raman spectroscopy and dynamic light scattering. The main goal of the studies performed was to compare the temperature of the transformation in three titania precursors obtained by different methods of soft chemistry routes and to evaluate dielectric properties of rutile products by means of broadband dielectric spectroscopy. Different factors affecting the electrical properties of calcinated products were discussed. It was found that sol-gel synthesis provided rutile form after annealing at 850°C with the smallest particles size about 20 nm, the highest value of dielectric permittivity equal to 63.7, and loss tangent equal to 0.051 at MHz frequencies. The other powders transformed to rutile at higher temperature, that is, 900°C, exhibit lower value of dielectric permittivity and had a higher value of particles size. The correlation between the anatase-rutile transformation temperature and the size of annealed particles was proposed.

  13. Experimental investigation of the electromechanical phase transition in a dielectric elastomer tube

    International Nuclear Information System (INIS)

    A membrane of dielectric elastomer undergoes a large deformation when it is subjected to a voltage through the thickness. Due to the attributes of light weight and high energy density, dielectric elastomers are suitable for electromechanical actuators and generators. In this work, the phenomenon of electromechanical phase transition is demonstrated experimentally in a tube of dielectric elastomer subjected to an internal pressure, an axial force and a voltage. When the voltage exceeds a critical value, the homogeneous deformation becomes unstable, and the tube deforms into coexistent states of bulged and unbulged sections. At the transition voltage the unbulged sections gradually bulge up and propagate. Two stable states are observed at the end of the phase transition process: one is coexistent states of the bulged and unbulged sections; the other is the wholly bulged tube. The achieved maximum voltage-induced deformation of the tube is 2200% in area, and the electromechanical energy conversion density is estimated to be 1.13 J g−1. These results are beyond the largest values reported in the literature. A theoretical analysis based on thermodynamics is carried out to qualitatively explain the observed experimental phenomenon. (paper)

  14. Changes in the dielectric properties of medaka fish embryos during development, studied by electrorotation.

    Science.gov (United States)

    Shirakashi, Ryo; Mischke, Miriam; Fischer, Peter; Memmel, Simon; Krohne, Georg; Fuhr, Günter R; Zimmermann, Heiko; Sukhorukov, Vladimir L

    2012-11-01

    The Japanese medaka fish, Oryzias latipes, has become a powerful vertebrate model organism in developmental biology and genetics. The present study explores the dielectric properties of medaka embryos during pre-hatching development by means of the electrorotation (ROT) technique. Due to their layered structure, medaka eggs exhibited up to three ROT peaks in the kHz-MHz frequency range. During development from blastula to early somite stage, ROT spectra varied only slightly. But as the embryo progressed to the late-somite stage, the ROT peaks underwent significant changes in frequency and amplitude. Using morphological data obtained by light and electron microscopy, we analyzed the ROT spectra with a three-shell dielectric model that accounted for the major embryonic compartments. The analysis yielded a very high value for the ionic conductivity of the egg shell (chorion), which was confirmed by independent osmotic experiments. A relatively low capacitance of the yolk envelope was consistent with its double-membrane structure revealed by transmission electron microscopy. Yolk-free dead eggs exhibited only one co-field ROT peak, shifted markedly to lower frequencies with respect to the corresponding peak of live embryos. The dielectric data may be useful for monitoring the development and changes in fish embryos' viability/conditions in basic research and industrial aquaculture. PMID:23063978

  15. Membrane Automata with Priorities

    Institute of Scientific and Technical Information of China (English)

    Luděk Cienciala; Lucie Ciencialová

    2004-01-01

    In this paper the one-way P automata with priorities are introduced. Such automata are P systemshere the membranes are only allowed to consume objects from parent membranes, under the given conditions. The result of computation of these systems is the set of multiset sequences consumed by skin membrane intc the system. The rules associated in some order with each membrane cannot modify any objects, they can only move them through membrane. We show that P automata with priorities and two membranes can accept every recursively enumerated language.

  16. [Affective dependency].

    Science.gov (United States)

    Scantamburlo, G; Pitchot, W; Ansseau, M

    2013-01-01

    Affective dependency is characterized by emotional distress (insecure attachment) and dependency to another person with a low self-esteem and reassurance need. The paper proposes a reflection on the definition of emotional dependency and the confusion caused by various denominations. Overprotective and authoritarian parenting, cultural and socio-environmental factors may contribute to the development of dependent personality. Psychological epigenetic factors, such as early socio-emotional trauma could on neuronal circuits in prefronto-limbic regions that are essential for emotional behaviour.We also focus on the interrelations between dependent personality, domestic violence and addictions. The objective for the clinician is to propose a restoration of self-esteem and therapeutic strategies focused on autonomy. PMID:23888587

  17. Polyphophoinositides components of plant nuclear membranes

    International Nuclear Information System (INIS)

    The polyphosphoinositides, phosphatidylinositol monophosphate (PIP) and phosphatidylinositol bisphosphate (PIP2), have been shown to be important components in signal transduction in many animal cells. Recently, these lipids have been found to be associated with plasma membrane but not microsomal membrane isolated from fusogenic wild carrot cells; however, in that study the lipids of the nuclear membrane were not analyzed. Since polyphosphoinositides had been shown to be associated with the nuclear membranes as well as the plasma membrane in some animal cells, it was important to determine whether they were associated with plant nuclear membranes as well. Cells were labeled for 18h with [3H] inositol and the nuclei were isolated by a modification of the procedure of Saxena et al. Preliminary lipid analyses indicate lower amount of PIP and PIP2 in nuclear membranes compared to whole protoplasts. This suggests that the nuclear membranes of carrot cells are not enriched in PIP and PIP2; however, the Triton X-100 used during the nuclear isolation procedure may have affected the recovery of the lipids. Experiments are in progress to determine the effects of Triton X-100 on lipid extraction

  18. Surface modification of chitosan/PEO nanofibers by air dielectric barrier discharge plasma for acetylcholinesterase immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Dorraki, Naghme, E-mail: n.dorraki@web.sbu.ac.ir [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Safa, Nasrin Navab [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Jahanfar, Mehdi [Protein Research Center, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Ghomi, Hamid [Laser and Plasma Research Institute, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of); Ranaei-Siadat, Seyed-Omid [Protein Research Center, Shahid Beheshti University, Evin 1983963113, Tehran (Iran, Islamic Republic of)

    2015-09-15

    Highlights: • We used an economical and effective method for surface modification. • Chitosan/PEO nanofibrous membranes were modified by air-DBD plasma. • The most NH{sub 3}{sup +} group was generated on the 6 min plasma modified membrane. • We immobilized acetylcholinesterase on the plasma modified and unmodified membranes. • More enzyme activity was detected on the modified membrane by plasma. - Abstract: There are different methods to modify polymer surfaces for biological applications. In this work we have introduced air-dielectric barrier discharge (DBD) plasma at atmospheric pressure as an economical and safe method for modifying the surface of electrospun chitosan/PEO (90/10) nanofibers for acetylcholinesterase (AChE) immobilization. According to the contact angle measurement results, the nanofibers become highly hydrophilic when they are exposed to the DBD plasma for 6 min in compared to unmodified membrane. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) results reveal hydroxyl, C=O and NH{sub 3}{sup +} polar groups increment after 6 min plasma treatment. Contact angle measurements and ATR-FTIR results are confirmed by X-ray photoelectron spectroscopy (XPS). AChE at pH 7.4 carries a negative charge and after immobilization on the surface of plasma-treated nanofibrous membrane attracts the NH{sub 3}{sup +} group and more enzyme activity is detected on the plasma-modified nanofibers for 6 min in compared to unmodified nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used for the surface topography and morphology characterization. The results have proved that air-DBD plasma is a suitable method for chitosan/PEO nanofibrous membrane modification as a biodegradable and functionalized substrate for enzyme immobilization.

  19. Surface modification of chitosan/PEO nanofibers by air dielectric barrier discharge plasma for acetylcholinesterase immobilization

    International Nuclear Information System (INIS)

    Highlights: • We used an economical and effective method for surface modification. • Chitosan/PEO nanofibrous membranes were modified by air-DBD plasma. • The most NH3+ group was generated on the 6 min plasma modified membrane. • We immobilized acetylcholinesterase on the plasma modified and unmodified membranes. • More enzyme activity was detected on the modified membrane by plasma. - Abstract: There are different methods to modify polymer surfaces for biological applications. In this work we have introduced air-dielectric barrier discharge (DBD) plasma at atmospheric pressure as an economical and safe method for modifying the surface of electrospun chitosan/PEO (90/10) nanofibers for acetylcholinesterase (AChE) immobilization. According to the contact angle measurement results, the nanofibers become highly hydrophilic when they are exposed to the DBD plasma for 6 min in compared to unmodified membrane. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) results reveal hydroxyl, C=O and NH3+ polar groups increment after 6 min plasma treatment. Contact angle measurements and ATR-FTIR results are confirmed by X-ray photoelectron spectroscopy (XPS). AChE at pH 7.4 carries a negative charge and after immobilization on the surface of plasma-treated nanofibrous membrane attracts the NH3+ group and more enzyme activity is detected on the plasma-modified nanofibers for 6 min in compared to unmodified nanofibers. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used for the surface topography and morphology characterization. The results have proved that air-DBD plasma is a suitable method for chitosan/PEO nanofibrous membrane modification as a biodegradable and functionalized substrate for enzyme immobilization

  20. Poring over membranes

    OpenAIRE

    Williams, Peter A.

    2008-01-01

    A new book on membrane science and technology focuses on the use of atomic force microscopy in the study and characterization of polymer membranes and also provides practical tips on how to undertake an experiment.

  1. Oxygen transport membrane

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof.......The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof....

  2. Solvent resistant nanofiltration membranes

    OpenAIRE

    Dutczak, Szymon Maria

    2011-01-01

    This thesis describes preparation and characterization of membranes for organic solvent filtration (OSF). The main aim was developing membranes for solvent resistant nanofiltration (SRNF) with molecular weight cut-off below 500 g mol-1.

  3. Premature rupture of membranes

    Science.gov (United States)

    ... When the water breaks early, it is called premature rupture of membranes (PROM). Most women will go ... th week of pregnancy, it is called preterm premature rupture of membranes (PPROM). The earlier your water ...

  4. Ionene membrane battery separator

    Science.gov (United States)

    Moacanin, J.; Tom, H. Y.

    1969-01-01

    Ionic transport characteristics of ionenes, insoluble membranes from soluble polyelectrolyte compositions, are studied for possible application in a battery separator. Effectiveness of the thin film of separator membrane essentially determines battery lifetime.

  5. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  6. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  7. Specific ion effects on membrane potential and the permselectivity of ion exchange membranes

    KAUST Repository

    Geise, Geoffrey M.

    2014-08-26

    © the Partner Organisations 2014. Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The

  8. Dielectric Elastomers for Fluidic and Biomedical Applications

    Science.gov (United States)

    McCoul, David James

    Dielectric elastomers have demonstrated tremendous potential as high-strain electromechanical transducers for a myriad of novel applications across all engineering disciplines. Because their soft, viscoelastic mechanical properties are similar to those of living tissues, dielectric elastomers have garnered a strong foothold in a plethora of biomedical and biomimetic applications. Dielectric elastomers consist of a sheet of stretched rubber, or elastomer, coated on both sides with compliant electrode materials; application of a voltage generates an electrostatic pressure that deforms the elastomer. They can function as soft generators, sensors, or actuators, and this last function is the focus of this dissertation. Many design configurations are possible, such as stacks, minimum energy structures, interpenetrating polymer networks, shape memory dielectric elastomers, and others; dielectric elastomers are already being applied to many fields of biomedicine. The first part of the original research presented in this dissertation details a PDMS microfluidic system paired with a dielectric elastomer stack actuator of anisotropically prestrained VHB(TM) 4910 (3M(TM)) and single-walled carbon nanotubes. These electroactive microfluidic devices demonstrated active increases in microchannel width when 3 and 4 kV were applied. Fluorescence microscopy also indicated an accompanying increase in channel depth with actuation. The cross-sectional area strains at 3 and 4 kV were approximately 2.9% and 7.4%, respectively. The device was then interfaced with a syringe pump, and the pressure was measured upstream. Linear pressure-flow plots were developed, which showed decreasing fluidic resistance with actuation, from 0.192 psi/(microL/min) at 0 kV, to 0.160 and 0.157 psi/(microL/min) at 3 and 4 kV, respectively. This corresponds to an ~18% drop in fluidic resistance at 4 kV. Active de-clogging was tested in situ with the device by introducing ~50 microm diameter PDMS microbeads and

  9. Time-resolved photoluminescence for evaluating laser-induced damage during dielectric stack ablation in silicon solar cells

    Science.gov (United States)

    Parola, Stéphanie; Blanc-Pélissier, Danièle; Barbos, Corina; Le Coz, Marine; Poulain, Gilles; Lemiti, Mustapha

    2016-06-01

    Selective laser ablation of dielectric layers on crystalline silicon wafers was investigated for solar cell fabrication. Laser processing was performed on Al2O3, and bi-layers Al2O3/SiNX:H with a nanosecond UV laser at various energy densities ranging from 0.4 to 2 J cm-2. Ablation threshold was correlated to the simulated temperature at the interface between the dielectric coatings and the silicon substrate. Laser-induced damage to the silicon substrate was evaluated by time-resolved photoluminescence. The minority carrier lifetime deduced from time-resolved photoluminescence was related to the depth of the heat affected zone in the substrate.

  10. Fabrication and Properties of Multilayer Chitosan Membrane Loaded with Tinidazole

    Institute of Scientific and Technical Information of China (English)

    HONG Hua; CHI Ping; LIU Changsheng

    2007-01-01

    With the aim of providing effective periodontal disease therapeutic method, multilayer membranes which were loaded with drug for guided tissue regeneration were prepared using an immerseprecipitation phase inversion technique. Single layer, bi-layer and tri-layer membranes were fabricated with chitosan used as carrier and tinidazole as medicine model which was loaded on the membrane. The influence of layer on structure and properties of membrane were studied by SEM, UV spectrophotometer and mechanical test. Drug release properties of three types of layer membranes were also investigated. The results showed that release rate could be slown down in both bi-layer and tri-layer membranes (to 11 days and 14 days respectively)and tri-layer membrane lasted the longest. After a process of rapid release, the concentration of tinidazole which was released by the membrane was maintained at an efficient dosage level. Compared with single layer and bilayer membranes, we found tri-layer membrane could play a role in controlling low-rate drug release especially at the early stage of release, and keep an efficient dosage at affected part for a long period of time. The loss of drug which loaded on membrane decreased from 84.6% for single layer to 13.04% for tri-layer. The mechanical strength of three types of membrane were detected and showed that it could meet the requiremens of clinical practice. The membranes especially with tri-layer could be more valuable in application.

  11. Membrane Curvature in Flaviviruses

    OpenAIRE

    Zhang, Wei; Kaufmann, Bärbel; Chipman, Paul R.; Kuhn, Richard J; Rossmann, Michael G.

    2013-01-01

    Coordinated interplay between membrane proteins and the lipid bilayer is required for such processes as transporter function and the entrance of enveloped viruses into host cells. In this study, three-dimensional cryo-electron microscopy density maps of mature and immature flaviviruses were analyzed to assess the curvature of the membrane leaflets and its relation to membrane-bound viral glycoproteins. The overall morphology of the viral membrane is determined by icosahedral scaffolding compo...

  12. Flux recovery of ceramic tubular membranes fouled with whey proteins: Some aspects of membrane cleaning

    Directory of Open Access Journals (Sweden)

    Popović Svetlana S.

    2008-01-01

    Full Text Available Efficiency of membrane processes is greatly affected by the flux reduction due to the deposits formation at the surface and/or in the pores of the membrane. Efficiency of membrane processes is affected by cleaning procedure applied to regenerate flux. In this work, flux recovery of ceramic tubular membranes with 50 and 200 nm pore size was investigated. The membranes were fouled with reconstituted whey solution for 1 hour. After that, the membranes were rinsed with clean water and then cleaned with sodium hydroxide solutions or formulated detergents (combination of P3 Ultrasil 67 and P3 Ultrasil 69. Flux recovery after the rinsing step was not satisfactory although fouling resistance reduction was significant so that chemical cleaning was necessary. In the case of 50 nm membrane total flux recovery was achieved after cleaning with 1.0% (w/w sodium hydroxide solution. In the case of 200 nm membrane total flux recovery was not achieved irrespective of the cleaning agent choice and concentration. Cleaning with commercial detergent was less efficient than cleaning with the sodium hydroxide solution.

  13. Alternate Fuel Cell Membranes for Energy Independence

    Energy Technology Data Exchange (ETDEWEB)

    Storey, Robson, F.; Mauritz, Kenneth, A.; Patton, Derek, L.; Savin, Daniel, A.

    2012-12-18

    performance properties of experimental membranes, 9) fabrication and FC performance testing of membrane electrode assemblies (MEA) from experimental membranes, and 10) measurement of ex situ and in situ membrane durability of experimental membranes. Although none of the experimental hydrocarbon membranes that issued from the project displayed proton conductivities that met DOE requirements, the project contributed to our basic understanding of membrane structure-property relationships in a number of key respects. An important finding of the benchmark studies is that physical degradation associated with humidity and temperature variations in the FC tend to open new fuel crossover pathways and act synergistically with chemical degradation to accelerate overall membrane degradation. Thus, for long term membrane survival and efficient fuel utilization, membranes must withstand internal stresses due to humidity and temperature changes. In this respect, rigid aromatic hydrocarbon fuel cell membranes, e.g. PAES, offer an advantage over un-modified Nafion membranes. The benchmark studies also showed that broadband dielectric spectroscopy is a potentially powerful tool in assessing shifts in the fundamental macromolecular dynamics caused by Nafion chemical degradation, and thus, this technique is of relevance in interrogating proton exchange membrane durability in fuel cells and macromolecular dynamics as coupled to proton migration, which is of fundamental relevance in proton exchange membranes in fuel cells. A key finding from the hydrocarbon membrane synthesis effort was that rigid aromatic polymers containing isolated ion exchange groups tethered tightly to the backbone (short tether), such as HPPS, provide excellent mechanical and durability properties but do not provide sufficient conductivity, in either random or block configuration, when used as the sole ion exchange monomer. However, we continue to hypothesize that longer tethers, and tethered groups spaced more closely

  14. Dielectric Constant Measurements for Characterizing Lunar Soils

    Science.gov (United States)

    Anderson, Robert C.; Buehler, M.; Seshadri, S.; Kuhlman, G.; Schaap, M.

    2005-01-01

    The return to the Moon has ignited the need to characterize the lunar regolith using fast, reliable in-situ methods. Characterizing the physical properties of the rocks and soils can be very difficult because of the many complex parameters that influence the measurements. In particular, soil electrical property measurements are influenced by temperature, mineral type, grain size, porosity, and soil conductivity. Determining the dielectric constant of lunar materials may be very important in providing quick characterization of surface deposits, especially for the Moon. A close examination of the lunar regolith samples collected by the Apollo astronauts indicates that the rocks and soils on the Moon are dominated by silicates and oxides. In this presentation, we will show that determining the dielectric constant measurements can provide a simple, quick detection method for minerals that contain titanium, iron, and water. Their presence is manifest by an unusually large imaginary permittivity.

  15. General properties of dielectric optical antennas.

    Science.gov (United States)

    Schuller, Jon A; Brongersma, Mark L

    2009-12-21

    Using Mie theory we derive a number of general results concerning the resonances of spherical and cylindrical dielectric antennas. Specifically, we prove that the peak scattering cross-section of radiation-limited antennas depends only on the resonance frequency and thus is independent of refractive index and size, a result which is valid even when the resonator is atomic-scale. Furthermore, we derive scaling limits for the bandwidth of dielectric antennas and describe a cylindrical mode which is unique in its ability to support extremely large bandwidths even when the particle size is deeply subwavelength. Finally, we show that higher Q antennas may couple more efficiently to an external load, but the optimal absorption cross-section depends only on the resonance frequency. PMID:20052120

  16. Dielectric resonator antenna for applications in nanophotonics.

    Science.gov (United States)

    Malheiros-Silveira, Gilliard N; Wiederhecker, Gustavo S; Hernández-Figueroa, Hugo E

    2013-01-14

    Optical nanoantennas, especially of the dipole type, have been theoretically and experimentally demonstrated by many research groups. Likewise, the plasmonic waveguides and optical circuits have experienced significant advances. In radio frequencies and microwaves a category of antenna known as dielectric resonator antenna (DRA), whose radiant element is a dielectric resonator (DR), has been designed for several applications, including satellite and radar systems. In this letter, we explore the possibilities and advantages to design nano DRAs (NDRAs), i. e., DRAs for nanophotonics applications. Numerical demonstrations showing the fundamental antenna parameters for a circular cylindrical NDRA type have been carried out for the short (S), conventional (C), and long (L) bands of the optical communication spectrum. PMID:23389016

  17. Bimodal condensation silicone elastomers as dielectric elastomers

    DEFF Research Database (Denmark)

    Yu, Liyun; Madsen, Frederikke Bahrt; Skov, Anne Ladegaard

    , the top and bottom surfaces of the elastomer (7:3) prepared at 23oC and 50% humidity were tested by water contact angle and optical microscope. The results show the bimodal condensation elastomer possesses structural heterogeneity, which may lead to favourable properties for DE applications....... elastomers were prepared by mixing different mass ratios (9:1, 8:2, 7:3, 6:4, 5:5, 4:6) between long polydimethylsiloxane (PDMS) chains and short PDMS chains. The resulting elastomers were investigated with respect to their rheology, dielectric properties, tensile strength, electrical breakdown, as well as.......Moreover, a series of elastomers with the same mass ratio (7:3) between long and short PDMS chains were made at different humidity (90%, 70%, 50%, 30%, 10%) at 23oC. The dielectric and mechincal properties of the resulting elastomers were shown to depend strongly on the atmospheric humidity level.In addition...

  18. Optomechanical deformation and strain in elastic dielectrics

    CERN Document Server

    Sonnleitner, Matthias; Ritsch, Helmut

    2012-01-01

    Light forces induced by scattering and absorption in elastic dielectrics lead to local density modulations and deformations. These perturbations in turn modify light propagation in the medium and generate an intricate nonlinear response. We generalise an analytic approach where light propagation in one-dimensional media of inhomogeneous density is modelled as a result of multiple scattering between polarizable slices. Using the Maxwell stress tensor formalism we compute the local optical forces and iteratively approach self-consistent density distributions where the elastic back-action balances gradient- and scattering forces. For an optically trapped dielectric we derive the nonlinear dependence of trap position, stiffness and total deformation on the object's size and field configuration. Generally trapping is enhanced by deformation, which exhibits a periodic change between stretching and compression. This strongly deviates from qualitative expectations based on the change of photon momentum of light cross...

  19. Plasma generation by dielectric resonator arrays

    Science.gov (United States)

    Dennison, Stephen; Chapman, Adam; Luo, Wei; Lanagan, Michael; Hopwood, Jeffrey

    2016-06-01

    Arrays of dielectric resonators—illuminated by an antenna—are used to ignite and sustain multiple microwave plasmas in parallel. Calcium titanate cylindrical resonators were arranged in a linear array with separation distances between 0.5 and 5 mm. The operating frequency was near the HEM111 resonance of 1.1 GHz. Paschen curves of the breakdown field and voltage in argon atmosphere are consistent with parallel plate microwave breakdown except within discharge gaps of 1 mm or less. Sustaining of argon plasma between 0.5 Torr and 1 atm within the array is found to alter the electromagnetic scattering from the dielectric resonators, suggesting applications in plasma-reconfigurable metamaterials and photonic crystals.

  20. Temperature sensor based on dielectric optical microresonator

    Science.gov (United States)

    Rahman, Anisur

    2011-12-01

    An optical temperature sensor has been presented based on Whispering Gallery Mode (WGM) dielectric microresonator. The effect of Transverse Electric (TE) wave propagation in dielectric micro-spheres presented has been for optical resonances based on WGM. TE waves are characterized both theoretically and experimentally for large size parameter of the micro-spheres. A theoretical model has been developed based on asymptotic approach. The theoretical development is mathematically robust and significantly less complicated than existing approaches presented in the literature. The quality factor of experimental resonance spectra observed in the laboratory is calculated approximately in the order of 10 4 which is sensitive enough to detect micro or nano level temperature changes in the surrounding medium. The sensitivity of the Morphology Dependent Resonance (MDR) temperature sensor is wavelength change of 10 -9 m for one degree centigrade change in temperature. This sensor could potentially be used for nano technology, Micro-Electro-Mechanical Systems (MEMS) devices, and biomedical applications.

  1. Elements of a dielectric laser accelerator

    CERN Document Server

    McNeur, Joshua; Schönenberger, Norbert; Leedle, Kenneth J; Deng, Huiyang; Ceballos, Andrew; Hoogland, Heinar; Ruehl, Axel; Hartl, Ingmar; Solgaard, Olav; Harris, James S; Byer, Robert L; Hommelhoff, Peter

    2016-01-01

    The widespread use of high energy particle beams in basic research, medicine and coherent X-ray generation coupled with the large size of modern radio frequency (RF) accelerator devices and facilities has motivated a strong need for alternative accelerators operating in regimes outside of RF. Working at optical frequencies, dielectric laser accelerators (DLAs) - transparent laser-driven nanoscale dielectric structures whose near fields can synchronously accelerate charged particles - have demonstrated high-gradient acceleration with a variety of laser wavelengths, materials, and electron beam parameters, potentially enabling miniaturized accelerators and table-top coherent x-ray sources. To realize a useful (i.e. scalable) DLA, crucial developments have remained: concatenation of components including sustained phase synchronicity to reach arbitrary final energies as well as deflection and focusing elements to keep the beam well collimated along the design axis. Here, all of these elements are demonstrated wit...

  2. Bistable dielectric elastomer minimum energy structures

    Science.gov (United States)

    Zhao, Jianwen; Wang, Shu; McCoul, David; Xing, Zhiguang; Huang, Bo; Liu, Liwu; Leng, Jinsong

    2016-07-01

    Dielectric elastomer minimum energy structures (DEMES) can realize large angular deformations by small voltage-induced strains, which make them an attractive candidate for use as soft actuators. If the task only needs binary action, the bistable structure will be an efficient solution and can save energy because it requires only a very short duration of voltage to switch its state. To obtain bistable DEMES, a method to realize the two stable states of traditional DEMES is provided in this paper. Based on this, a type of symmetrical bistable DEMES is proposed, and the required actuation pulse duration is shorter than 0.1 s. When a suitable mass is attached to end of the DEMES, or two layers of dielectric elastomer are affixed to both sides of the primary frame, the DEMES can realize two stable states and can be switched by a suitable pulse duration. To calculate the required minimum pulse duration, a mathematical model is provided and validated by experiment.

  3. Model cell membranes

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Nylander, Tommy; Cardenas Gomez, Marite

    2014-01-01

    The high complexity of biological membranes has motivated the development and application of a wide range of model membrane systems to study biochemical and biophysical aspects of membranes in situ under well defined conditions. The aim is to provide fundamental understanding of processes control...

  4. Dielectric behaviour of erbium substituted Mn–Zn ferrites

    Indian Academy of Sciences (India)

    D Ravinder; K Vijaya Kumar

    2001-10-01

    Dielectric properties such as dielectric constant (') and dielectric loss tangent (tan ⋹ ) of mixed Mn–Zn–Er ferrites having the compositional formula Mn0.58Zn0.37Fe2.05–ErO4 (where = 0.2, 0.4, 0.6, 0.8 and 1.0) were measured at room temperature in the frequency range 1–13 MHz using a HP 4192A impedance analyser. Plots of dielectric constant (') vs frequency show a normal dielectric behaviour of spinel ferrites. The frequency dependence of dielectric loss tangent (tan ) was found to be abnormal, giving a peak at certain frequency for all mixed Mn–Zn–Er ferrites. A qualitative explanation is given for the composition and frequency dependence of the dielectric constant and dielectric loss tangent. Plots of dielectric constant vs temperature have shown a transition near the Curie temperature for all the samples of Mn–Zn–Er ferrites. However, Mn0.58Zn0.37Er1.0Fe1.05O4 does not show a transition. On the basis of these results an explanation for the dielectric mechanism in Mn–Zn–Er ferrites is suggested.

  5. Dielectric Properties of Flocculated Water-in-Oil Emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Skodvin, T.

    1995-12-31

    When an offshore oil field is near completion, water occupies a large fraction of the available pore volume. Thus, in collecting the oil and gas reserves, one has to deal with a high co-production of either formation- or injected water. This doctoral thesis focuses on the effect of water-in-oil emulsions on the dielectric properties, in particular the effect of flocculation. Various dielectric models are applied to obtain methods for qualitative and quantitative characterization of the flocculated state. Permittivity and measurement of dielectric properties are discussed as a basis for the interpretation of the dielectric properties of the emulsions. Various flocculation models are presented. It is concluded that the dielectric properties of water-in-oil emulsions are strongly influenced by continuously ongoing processes in the system. Because of flocculation and sedimentation the traditional dielectric mixture models cannot satisfactorily predict the dielectric behaviour. The experimentally obtained permittivities for the emulsions can be reproduced by including flocculation in the models and treating the floc aggregates as spheroids or subsystems with dielectric properties given by the degree of flocculation. The models discussed have difficulties reproducing the complete frequency behaviour found experimentally. This is probably because the dielectric relaxation may be influenced by processes not included in the models, such as the effects of dipolar or multipolar interactions between the droplets. For further research it is recommended that rheological and dielectric measurements be combined. 227 refs., 61 figs., 16 tabs.

  6. Ionic Block Copolymers for Anion Exchange Membranes

    Science.gov (United States)

    Tsai, Tsung-Han; Herbst, Dan; Giffin, Guinevere A.; di Noto, Vito; Witten, Tom; Coughlin, E. Bryan

    2013-03-01

    Anion exchange membrane (AEM) fuel cells have regained interest because it allows the use of non-noble metal catalysts. Until now, most of the studies on AEM were based on random polyelectrolytes. In this work, Poly(vinylbenzyltrimethylammonium bromide)-b- (methylbutylene) ([PVBTMA][Br]-b-PMB) was studied by SAXS, TEM and dielectric spectroscopy to understand the fundamental structure-conductivity relationship of ion transport mechanisms within well-ordered block copolymers. The ionic conductivity and the formation of order structure were dependent on the casting solvent. Higher ion exchange capacity (IEC) of the membranes showed higher conductivity at as IEC values below 1.8mmol/g, as above this, the ionic conductivity decreases due to more water uptake leading to dilution of charge density. The humidity dependence of morphology exhibited the shifting of d-spacing to higher value and the alteration in higher characteristic peak of SAXS plot as the humidity increase from the dry to wet state. This phenomenon can be further explained by a newly developed polymer brush theory. Three ionic conduction pathways with different conduction mechanism within the membranes can be confirmed by broadband electric spectroscopy. US Army MURI (W911NF1010520)

  7. Evaluations of intrinsic time dependent dielectric breakdown of dielectric copper diffusion barriers

    International Nuclear Information System (INIS)

    Study of the intrinsic time dependent dielectric breakdown (TDDB) of dielectric copper diffusion barriers was realized using a unique planar capacitor (Pcap) test structure. The test vehicle has several advantages over the metal dot method. The most important one is the elimination of field enhancement effect which could be more than 50% in the case of metal dots. In order to test the effectiveness of this test vehicle, two different dielectric barriers, one conventional SiCN film and the other a BN film still under development, were selected for TDDB evaluations. Significant differences were observed between the two films in TDDB lifetime, the shape parameter β of the Weibull failure time distributions, and the characteristics of the current versus time curves. The BN film had a degradation of more than four orders of magnitude in TDDB lifetime than SiCN. The Weibull shape parameter β of SiCN was 8.4, among the highest values that have been reported for any dielectric barrier films, versus 1.4 for the boron nitride film. Furthermore, the SiCN film showed a decrease in current versus time curves during the initial stage of the stressing, a trend which is typically related to charge trapping in defect-free films. This was not the case for the BN film where the leakage currents were much higher. The results demonstrate that the Pcap test structure is an effective vehicle to evaluate the intrinsic reliability of dielectric barrier films.

  8. Highly tunable elastic dielectric metasurface lenses

    OpenAIRE

    Kamali, Seyedeh Mahsa; Arbabi, Ehsan; Arbabi, Amir; Horie, Yu; Faraon, Andrei

    2016-01-01

    Dielectric metasurfaces are two-dimensional structures composed of nano-scatterers that manipulate phase and polarization of optical waves with subwavelength spatial resolution, enabling ultra-thin components for free-space optics. While high performance devices with various functionalities, including some that are difficult to achieve using conventional optical setups have been shown, most demonstrated components have a fixed functionality. Here we demonstrate highly tunable metasurface devi...

  9. Extremely Thin Dielectric Metasurface for Carpet Cloaking

    OpenAIRE

    Hsu, LiYi; Lepetit, Thomas; Kanté, Boubacar

    2015-01-01

    We demonstrate a novel and simple approach to cloaking a scatterer on a ground plane. We use an extremely thin dielectric metasurface ({\\lambda}/12) to reshape the wavefronts distorted by a scatterer in order to mimic the reflection pattern of a flat ground plane. To achieve such carpet cloaking, the reflection angle has to be equal to the incident angle everywhere on the scatterer. We use a graded metasurface and calculate the required phase gradient to achieve cloaking. Our metasurface loca...

  10. Dielectric elastomer generators that stack up

    International Nuclear Information System (INIS)

    This paper reports the design, fabrication, and testing of a soft dielectric elastomer power generator with a volume of less than 1 cm3. The generator is well suited to harvest energy from ambient and from human body motion as it can harvest from low frequency (sub-Hz) motions, and is compact and lightweight. Dielectric elastomers are highly stretchable variable capacitors. Electrical energy is produced when the deformation of a stretched, charged dielectric elastomer is relaxed; like-charges are compressed together and opposite-charges are pushed apart, resulting in an increased voltage. This technology provides an opportunity to produce soft, high energy density generators with unparalleled robustness. Two major issues block this goal: current configurations require rigid frames that maintain the dielectric elastomer in a prestretched state, and high energy densities have come at the expense of short lifetime. This paper presents a self-supporting stacked generator configuration which does not require rigid frames. The generator consists of 48 generator films stacked on top of each other, resulting in a structure that fits within an 11 mm diameter footprint while containing enough active material to produce useful power. To ensure sustainable power production, we also present a mathematical model for designing the electronic control of the generator which optimizes energy production while limiting the electrical stress on the generator below failure limits. When cyclically compressed at 1.6 Hz, our generator produced 1.8 mW of power, which is sufficient for many low-power wireless sensor nodes. This performance compares favorably with similarly scaled electromagnetic, piezoelectric, and electrostatic generators. The generator’s small form factor and ability to harvest useful energy from low frequency motions such as tree swaying or shoe impact provides an opportunity to deliver power to remote wireless sensor nodes or to distributed points in the human body

  11. Magnetic Resonance Imaging with a Dielectric Lens

    OpenAIRE

    Vazquez, F.; Marrufo, O.; MARTIN,R; Rodriguez, A. O.

    2009-01-01

    Recently, metamaterials have been introduced to improve the signal-to-noise ratio (SNR) of magnetic resonance images with very promising results. However, the use polymers in the generation of high quality images in magnetic resonance imaging has not been fully been investigated. These investigations explored the use of a dielectric periodical array as a lens to improve the image SNR generated with single surface coils. Commercial polycarbonate glazing sheets were used together with a circula...

  12. Modeling of Dielectric Heating within Lyophilization Process

    Directory of Open Access Journals (Sweden)

    Jan Kyncl

    2014-01-01

    Full Text Available A process of lyophilization of paper books is modeled. The process of drying is controlled by a dielectric heating system. From the physical viewpoint, the task represents a 2D coupled problem described by two partial differential equations for the electric and temperature fields. The material parameters are supposed to be temperature-dependent functions. The continuous mathematical model is solved numerically. The methodology is illustrated with some examples whose results are discussed.

  13. Modeling of Dielectric Heating within Lyophilization Process

    OpenAIRE

    Jan Kyncl; Jiří Doubek; Lubomír Musálek

    2014-01-01

    A process of lyophilization of paper books is modeled. The process of drying is controlled by a dielectric heating system. From the physical viewpoint, the task represents a 2D coupled problem described by two partial differential equations for the electric and temperature fields. The material parameters are supposed to be temperature-dependent functions. The continuous mathematical model is solved numerically. The methodology is illustrated with some examples whose results are discussed.

  14. Partial discharges and bulk dielectric field enhancement

    OpenAIRE

    McAllister, Iain Wilson; Johansson, Torben

    2000-01-01

    A consequence of partial discharge activity within a gaseous void is the production of a field enhancement in the solid dielectric in the proximity of the void. This situation arises due to the charge created by the partial discharges accumulating at the void wall. The influence of the spatial extent of this wall charge upon the maximum field strength in the solid is examined and discussed.

  15. Dielectric-Barrier Discharges. Principle and Applications

    OpenAIRE

    Kogelschatz, U.; Eliasson, B.; Egli, W.

    1997-01-01

    Dielectric-barrier discharges (silent discharges) are non-equilibrium discharges that can be conveniently operated over a wide temperature and pressure range. At about atmospheric pressure electrical breakdown occurs in many independent thin current filaments. These short-lived microdischarges have properties of transient high pressure glow discharges with electron energies ideally suited for exciting or dissociating background gas atoms and molecules. The traditional application for large-sc...

  16. Attosecond clocking of scattering dynamics in dielectrics

    Science.gov (United States)

    Kling, Matthias

    2016-05-01

    In the past few years electronic-device scaling has progressed rapidly and miniaturization has reached physical gate lengths below 100 nm, heralding the age of nanoelectronics. Besides the effort in size scaling of integrated circuits, tremendous progress has recently been made in increasing the switching speed where strong-field-based ``dielectric-electronics'' may push it towards the petahertz frontier. In this contest, the investigation of the electronic collisional dynamics occurring in a dielectric material is of primary importance to fully understand the transport properties of such future devices. Here, we demonstrate attosecond chronoscopy of electron collisions in SiO2. In our experiment, a stream of isolated aerodynamically focused SiO2 nanoparticles of 50 nm diameter was delivered into the laser interaction region. Photoemission is initiated by an isolated 250 as pulse at 35 eV and the electron dynamics is traced by attosecond streaking using a delayed few-cycle laser pulse at 700 nm. Electrons were detected by a kilohertz, single-shot velocity-map imaging spectrometer, permitting to separate frames containing nanoparticle signals from frames containing the response of the reference gas only. We find that the nanoparticle photoemission exhibits a positive temporal shift with respect to the reference. In order to understand the physical origin of the shift we performed semi-classical Monte-Carlo trajectory simulations taking into account the near-field distributions in- and outside the nanoparticles as obtained from Mie theory. The simulations indicate a pronounced dependence of the streaking time shift near the highest measured electron energies on the inelastic scattering time, while elastic scattering only shows a small influence on the streaking time shift for typical dielectric materials. We envision our approach to provide direct time-domain access to inelastic scattering for a wide range of dielectrics.

  17. A beam steering technique using dielectric wedges.

    OpenAIRE

    Khan, M. R.

    1995-01-01

    The thesis describes a method of' beam steering aimed at producing a useful amount of deflection of an antenna beam from boresight, by a simple and Inexpensive method. For large antennas, It is difficult, as well as expensive, to steer the beam by more than a few beamwidths. The method studied was developed with particular reference to the beam steering requirements of Direct Broadcast Satellite flat plate antennas. The method involves two dielectric wedges, having cir...

  18. Dielectric elastomer generators that stack up

    Science.gov (United States)

    McKay, T. G.; Rosset, S.; Anderson, I. A.; Shea, H.

    2015-01-01

    This paper reports the design, fabrication, and testing of a soft dielectric elastomer power generator with a volume of less than 1 cm3. The generator is well suited to harvest energy from ambient and from human body motion as it can harvest from low frequency (sub-Hz) motions, and is compact and lightweight. Dielectric elastomers are highly stretchable variable capacitors. Electrical energy is produced when the deformation of a stretched, charged dielectric elastomer is relaxed; like-charges are compressed together and opposite-charges are pushed apart, resulting in an increased voltage. This technology provides an opportunity to produce soft, high energy density generators with unparalleled robustness. Two major issues block this goal: current configurations require rigid frames that maintain the dielectric elastomer in a prestretched state, and high energy densities have come at the expense of short lifetime. This paper presents a self-supporting stacked generator configuration which does not require rigid frames. The generator consists of 48 generator films stacked on top of each other, resulting in a structure that fits within an 11 mm diameter footprint while containing enough active material to produce useful power. To ensure sustainable power production, we also present a mathematical model for designing the electronic control of the generator which optimizes energy production while limiting the electrical stress on the generator below failure limits. When cyclically compressed at 1.6 Hz, our generator produced 1.8 mW of power, which is sufficient for many low-power wireless sensor nodes. This performance compares favorably with similarly scaled electromagnetic, piezoelectric, and electrostatic generators. The generator’s small form factor and ability to harvest useful energy from low frequency motions such as tree swaying or shoe impact provides an opportunity to deliver power to remote wireless sensor nodes or to distributed points in the human body

  19. Dielectric Breakdown Strength of Polyethylene Nanocomposites

    OpenAIRE

    Lau, K. Y.; A. S. Vaughan; Chen, G.

    2011-01-01

    The term “nanometric dielectrics” or simply “nanodielectrics” was introduced in 1994 when Lewis [1] anticipated the potential property changes that would benefit electrical insulation due to nano-sized inclusion. Such materials, containing homogenous dispersion of small amount (normally less than 10wt%) of nanoparticles (with at least one dimension in nanometre range) in host matrix, are of specific dielectric interest. Although much effort has been put forth to investigate the potential diel...

  20. A MEMS Dielectric Affinity Glucose Biosensor

    OpenAIRE

    Xian HUANG; Li, SiQi; Davis, Erin; Li, Dachao; Wang, Qian; Lin, Qiao

    2013-01-01

    Continuous glucose monitoring (CGM) sensors based on affinity detection are desirable for long-term and stable glucose management. However, most affinity sensors contain mechanical moving structures and complex design in sensor actuation and signal readout, limiting their reliability in subcutaneously implantable glucose detection. We have previously demonstrated a proof-of-concept dielectric glucose sensor that measured pre-mixed glucose-sensitive polymer solutions at various glucose concent...