Nonlinear electrohydrodynamic instability of a finitely conducting cylinder: Effect of interfacial surface charges

2004 ◽  
Vol 55 (1) ◽  
pp. 63-91 ◽  
Author(s):  
Abd Elmonem Khalil Elcoot ◽  
Abdel Raouf F. Elhefnawy ◽  
Galal M. Moatimid
Keyword(s):  
Surface Charges ◽  
Electrohydrodynamic Instability ◽  
Conducting Cylinder ◽  
Interfacial Surface

ELECTROHYDRODYNAMIC INSTABILITY OF LIQUID SHEET SATURATING POROUS MEDIUM WITH INTERFACIAL SURFACE CHARGES

2013 ◽  
Vol 23 (2) ◽  
pp. 165-191
Author(s):  
Mohamed F. El-Sayed ◽  
M. H. M. Moussa ◽  
Ahmed A. A. Hassan ◽  
N. M. Hafez
Keyword(s):  
Porous Medium ◽  
Liquid Sheet ◽  
Surface Charges ◽  
Electrohydrodynamic Instability ◽  
Interfacial Surface

Electrohydrodynamic instability of a cylindrical viscous jet

1969 ◽  
Vol 47 (11) ◽  
pp. 1215-1220 ◽  
Author(s):  
D. H. Michael ◽  
M. E. O'Neill
Keyword(s):  
Surface Wave ◽  
Electrohydrodynamic Instability ◽  
Electrically Conducting ◽  
Conducting Cylinder ◽  
Wave Disturbances ◽  
Viscous Jet

The electrohydrodynamic instability to small axisymmetrical surface wave disturbances of a circular, cylindrical, electrically conducting, viscous jet, which is projected along the axis of a circular conducting cylinder, is considered for the cases when the charges or potentials remain unaltered. The discussion given is applicable for arbitrary viscosities and it is shown that points of transition from stable to unstable modes of oscillation, or vice versa, are the same as for the inviscid jet.

Nonlinear Electrohydrodynamic Stability of Two Superposed Bounded Fluids in the Presence of Interfacial Surface Charges

1998 ◽  
Vol 53 (5) ◽  
pp. 217-232 ◽  
Author(s):  
M. F. El-Sayed ◽  
D. K. Callebaut
Keyword(s):  
Schrödinger Equation ◽  
Electric Field ◽  
Nonlinear Schrödinger Equation ◽  
Schrodinger Equation ◽  
Nonlinear Schrodinger Equation ◽  
Surface Charges ◽  
Nonlinear Schrödinger ◽  
Interfacial Surface ◽  
Lower Fluid ◽  
The One

Abstract The method of multiple scales is used to analyse the nonlinear propagation of waves on the interface between two superposed dielectric fluids with uniform depths in the presence of a normal electric field, taking into account the interfacial surface charges. The evolution of the amplitude for travelling waves is governed by a nonlinear Schrödinger equation which gives the criterion for modulational instability. Numerical results are given in graphical form, and some limiting cases are recovered. Three cases, in the pure hydrodynamical case, depending on whether the depth of the lower fluid is equal to or greater than or smaller than the one of the upper fluid are considered, and the effect of the electric field on the stability regions is determined. It is found that the effect of the electric field is the same in all the cases for small values of the field, and there is a value of the electric field after which the effect differs from case to case. It is also found that the effect of the electric field is stronger in the case where the depth of the lower fluid is larger than the one of the upper fluid. On the other hand, the evolution of the am-plitude for standing waves near the cut-off wavenumber is governed by another type of nonlinear Schrödinger equation with the roles of time and space are interchanged. This equation makes it possible to determine the nonlinear dispersion relation, and the nonlinear effect on the cut-off wavenumber.

scholarly journals High Electromechanical Deformation Based on Structural Beta-Phase Content and Electrostrictive Properties of Electrospun Poly(vinylidene fluoride- hexafluoropropylene) Nanofibers

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1817 ◽  
Author(s):  
Nikruesong Tohluebaji ◽  
Chatchai Putson ◽  
Nantakan Muensit
Keyword(s):  
Dielectric Properties ◽  
Smart Materials ◽  
Microelectromechanical Systems ◽  
Vinylidene Fluoride ◽  
Interfacial Polarization ◽  
Surface Charges ◽  
Thermal Compression ◽  
Β Phase ◽  
Interfacial Surface ◽  
Poly Vinylidene Fluoride

The poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) polymer based on electrostrictive polymers is essential in smart materials applications such as actuators, transducers, microelectromechanical systems, storage memory devices, energy harvesting, and biomedical sensors. The key factors for increasing the capability of electrostrictive materials are stronger dielectric properties and an increased electroactive β-phase and crystallinity of the material. In this work, the dielectric properties and microstructural β-phase in the P(VDF-HFP) polymer were improved by electrospinning conditions and thermal compression. The P(VDF-HFP) fibers from the single-step electrospinning process had a self-induced orientation and electrical poling which increased both the electroactive β-crystal phase and the spontaneous dipolar orientation simultaneously. Moreover, the P(VDF-HFP) fibers from the combined electrospinning and thermal compression achieved significantly enhanced dielectric properties and microstructural β-phase. Thermal compression clearly induced interfacial polarization by the accumulation of interfacial surface charges among two β-phase regions in the P(VDF-HFP) fibers. The grain boundaries of nanofibers frequently have high interfacial polarization, as they can trap charges migrating in an applied field. This work showed that the combination of electrospinning and thermal compression for electrostrictive P(VDF-HFP) polymers can potentially offer improved electrostriction behavior based on the dielectric permittivity and interfacial surface charge distributions for application in actuator devices, textile sensors, and nanogenerators.

A STUDY OF ELECTROMAGNETIC SCATTERING FROM A DIELECTRIC-COATED CONDUCTING CYLINDER

1992 ◽  
Vol 12 (2) ◽  
pp. 179-189
Author(s):  
Hengyu Ke ◽  
Siwen Huang ◽  
Wenjun Li
Keyword(s):  
Electromagnetic Scattering ◽  
Conducting Cylinder

The electrohydrodynamic instability in twisted nematic liquid crystals

1994 ◽  
Vol 4 (2) ◽  
pp. 239-252 ◽  
Author(s):  
A. Hertrich ◽  
A. P. Krekhov ◽  
O. A. Scaldin
Keyword(s):  
Liquid Crystals ◽  
Nematic Liquid Crystals ◽  
Electrohydrodynamic Instability ◽  
Twisted Nematic

Preparation of TiO2 Nano-particles with Controllable Surface Charges for Electrophoretic Display

2012 ◽  
Vol 27 (6) ◽  
pp. 649-654 ◽  
Author(s):  
Zhi-Jie LIU ◽  
Xiang-Gao LI ◽  
Shi-Rong WANG
Keyword(s):  
Nano Particles ◽  
Surface Charges ◽  
Electrophoretic Display

Carboxymethyl-hexanoyl Chitosan Nanodroplets for Ultrasonic Imaging and Drug Delivery to Tumor

2018 ◽  
Vol 24 (15) ◽  
pp. 1682-1688 ◽  
Author(s):  
Yu Jinsui ◽  
Situ Bing ◽  
Luo Muhua ◽  
Li Yue ◽  
Liao Jianyi ◽  
...  
Keyword(s):  
Ultrasound Imaging ◽  
Tumor Therapy ◽  
Carboxymethyl Chitosan ◽  
Great Promise ◽  
Ovarian Cancer Cells ◽  
Mechanical Index ◽  
Surface Charges ◽  
Particle Structure ◽  
Drug Release Profile ◽  
Hexanoyl Chitosan

Introduction: Although a great many strategies have been proposed for tumor-targeted chemotherapy, current delivery methods of anticancer drugs present limited success with inevitable systemic toxicity. The aim of this study was to develop a new kind of theranostic carrier for targeted tumor therapy. Methods: Prior to prepare CHC-PFP-DOX, carboxymethyl-hexanoyl chitosan (CHC) was synthesized by acylation of carboxymethyl chitosan. To develop CHC-PFP, perfluoropentane (PFP), an ultrasound gas precursor, was simultaneously encapsulated into the hydrophobic inner cores of pre-formulated CHC micelle in aqueous phase via using the oil in water (O/W) emulsion method. The size distribution and surface charges of these nanodroplets were measured and the morphology was observed by transmission electron microscopy (TEM). For ultrasound imaging application, in vitro model was established to evaluate the imaging of CHC-PFP-DOX under different concentration and mechanical index. After that, the anti-tumor effect of ultrasound combined with CHC-PFPDOX on ovarian cancer cells was investigated. Results: The resulting CHC-PFP-DOX had a nano-sized particle structure, with hydrophobic anticancer DOX/PFP inner cores and a hydrophilic carboxymethyl chitosan polymer outer shell. The favorable nano-scaled size offers the potential to extravagate from veins and accumulate in tumor tissues via enhanced permeation and retention (EPR) effect. Additionally, CHC-PFP-DOX showed the ability to serve as ultrasound imaging agent at body temperature. Notably, it exhibited an ultrasound-triggered drug release profile through the external ultrasound irradiation. Further study demonstrated that ultrasound combined with CHC-PFP-DOX can improve the killing effect of chemotherapy for tumor. Conclusion: CHC-PFP-DOX holds great promise in simultaneous cancer-targeting ultrasound imaging and ultrasound- mediated delivery for cancer chemotherapy.

Evaluation of Surface-modified Superparamagnetic Iron Oxide Nanoparticles to Optimize Bacterial Immobilization for Bio-separation with the Least Inhibitory Effect on Microorganism Activity

2020 ◽  
Vol 10 (2) ◽  
pp. 166-174
Author(s):  
Mehdi Khoshneviszadeh ◽  
Sarah Zargarnezhad ◽  
Younes Ghasemi ◽  
Ahmad Gholami
Keyword(s):  
Iron Oxide ◽  
Amino Acid ◽  
Magnetic Nanoparticles ◽  
Iron Oxide Nanoparticles ◽  
Surface Coating ◽  
Superparamagnetic Iron Oxide ◽  
Superparamagnetic Iron Oxide Nanoparticles ◽  
Oxide Nanoparticles ◽  
Surface Charges ◽  
Surface Modified

Background: Magnetic cell immobilization has been introduced as a novel, facile and highly efficient approach for cell separation. A stable attachment between bacterial cell wall with superparamagnetic iron oxide nanoparticles (SPIONs) would enable the microorganisms to be affected by an outer magnetic field. At high concentrations, SPIONs produce reactive oxygen species in cytoplasm, which induce apoptosis or necrosis in microorganisms. Choosing a proper surface coating could cover the defects and increase the efficiency. Methods: In this study, asparagine, APTES, lipo-amino acid and PEG surface modified SPIONs was synthesized by co-precipitation method and characterized by FTIR, TEM, VSM, XRD, DLS techniques. Then, their protective effects against four Gram-positive and Gram-negative bacterial strains including Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were examined through microdilution broth and compared to naked SPION. Results: The evaluation of characterization results showed that functionalization of magnetic nanoparticles could change their MS value, size and surface charges. Also, the microbial analysis revealed that lipo-amino acid coated magnetic nanoparticles has the least adverse effect on microbial strain among tested SPIONs. Conclusion: This study showed lipo-amino acid could be considered as the most protective and even promotive surface coating, which is explained by its optimizing effect on cell penetration and negligible reductive effects on magnetic properties of SPIONs. lipo-amino acid coated magnetic nanoparticles could be used in microbial biotechnology and industrial microbiology.

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