External Electrical Potentials Research Articles

Hitting times of quantum and classical random walks in potential spaces

The spatial search problem is an interesting and important problem in computer science and especially the area of algorithms. The objective is a marked site to be found in a finite physical space, that can be modeled as a finite lattice or a graph. Many approaches have been developed to address this problem. Classical random walks and quantum walks are efficient models that address the spatial search problem. Quantum walks is a universal model of quantum computation and can be mapped directly to quantum circuits and consequently executed on quantum computers. Quantum walks utilized for quantum search proved to achieve significantly lower hitting times than their classical counterpart, classical random walks. The evolution space for the quantum walks as well as the classical random walks is up until now a free space. In our approach, we introduce external electrical potentials to the evolution space. We study the evolution of discrete time quantum and classical random walks in such potential spaces and the probability — hitting time on finding marked sites. We considered the differences in applied potential among neighboring sites as weights for the lattice — graph. We introduce these weights to the evolution space as an operator for the discrete time quantum walk and as coin probabilities for the classical random walk. Our results show that quantum walks again, evolve faster in the evolution space with the applied potential. Quantum walks also achieve better probability — hitting time on finding the marked site in the potential space. With the introduction of electrical potentials, quantum walks evolving in potential spaces, can lead to the development of novel quantum algorithms, where input parameters can be introduced as external potentials.

A comparative study on the vibration of functionally graded Magneto-Electro-Elastic rectangular plate rested on a Pasternak foundation based on exponential and first-order shear deformation theories

In this paper, the in-plane and out-of-plane free vibrations of the functionally graded magneto-electro-elastic (FG-MEE) rectangular plate on a pasternak foundation were evaluated based on exponential shear deformation theory (ESDT) and first order shear deformation theory (FSDT). The material properties of FG-MEE varied along the thickness according to a power-law distribution model. It was assumed that the FG-MEE plate is subjected to initial external electrical and magnetic potentials; mreover, simply-supported boundary conditions were considered for all the edges of the FG-MEE plate. Firstly, the corresponding partial differential equations (PDEs) were derived using Hamilton’s principle, then, the natural frequencies were determined by solving the obtained equations through Navier’s approach according to the assumed boundary conditions. The results revealed that the natural frequencies of the plate decrease/increase with the increase of the electric/magnetic potentials. Moreover, the results showed a 0.03%, difference between the natural frequencies of the plate with a thickness-to-length ratio of 0.1 based on FSDT and ESDT; when the aspect ratio was increased to 0.2 and 0.3 this difference rose to 0.2% and 0.5%, respectively.

Deproteinized Natural Rubber as an Electrically Controllable, Transdermal Drug-Delivery Patch

A soft transdermal drug-delivery (TDD) patch composed of deproteinized natural rubber (DPNR) was fabricated in this work. Sulindac (Sul), an anionic drug, was loaded on the DPNR patch using silicone oil as a plasticizer. The in vitro release-permeation behavior of Sul from the Sul-loaded DPNR patch was studied by using a modified Franz diffusion cell at a pH of 7.4 and temperature of 37 °C. A cytotoxicity test of the DPNR with silicone oil (DPNR-Si) patch was performed, and the viability percentage was 90%. When external electrical potentials of 0–9 V were applied, the maximum amounts of Sul released and permeated from the Sul-loaded DPNR patch were 8.34, 10.16, 11.86, 19.84, 54.73, 70.89, 82.25, and 83.02% for electrical potentials of 0, 0.1, 0.3, 1, 3, 5, 7, and 9 V, respectively. The release and permeation amount of Sul increased with the increasing electrical potential because of the electrorepulsive force, expanded pathway in pigskin, and pore formation in DPNR. Pore formation occurred under an applied electric field, as confirmed by optical micrographs. The porosity percentage increased with the increasing time and electrical potential due to the drug release and permeation and lack of plasticizer. The effect of storage time on the permeation characteristics was studied for 3 months. The release and permeation amount of Sul was 8.61 and 6.80 wt% for storage times of 1 and 3 months, respectively. Thus, the fabricated Sul-loaded DPNR patch is an electrically controllable TDD patch.

High-resolution mapping of single neurons provides insight into neuron structure and LFP generation

Recent modeling [1] has suggested that the spatial structure of single neurons, especially the orientation and the shape of their dendritic trees, is of great importance in the understanding of the properties of the LFP generated (for example, a low-pass filtering effect has been shown in remote neurites [2]). In order to test these predictions, high-density microelectrode arrays (MEAs) featuring 11'011 electrodes are a valuable tool [3]. They provide detailed information about the external electrical field potentials of cultured neurons, from which the relevant information about single neurons properties must be extracted. We developed an on-line software allowing us to track neurites of single neurons (Figure 1A-K, footprint of a neuron), which provides information about their spatial structure and their activity dynamics leading to predictions on their morphology (Figure ​(Figure1L).1L). These allow us to elucidate additional properties of LFP generation, such as, multi-polar potentials related to the morphology of the studied cell. Moreover, reconstruction of the morphology of different cells was performed based on footprints and compared with imaging from GFP-stained neural cultures. Figure 1

Electrical potential modulation of dynamic film properties of aqueous surfactant solutions through a nanogap

The effect of external electrical potentials (EEPs) on aqueous surfactant films nanoconfined in a ball-plate configuration has been investigated by measuring the dynamic film thickness with an interferometer. Experimental results indicate that the film formation properties of the surfactant solutions in the nanogap under applied EEPs are strongly dependent on the interfacial adsorbed surfactant structure. Effective control over the film formation properties by applying EEPs depends on the signs of the charges on the solid surface and the surfactant headgroups, the surfactant concentration, and the magnitude of EEPs. Remarkable alterations of the film formation properties in the nanogap by EEPs can be observed except when the surface charge is the same in sign as the headgroups and the surfactant concentration is above the critical micelle concentration. Mechanisms of these phenomena have been discussed in this work.

A nanochannel‐based concentrator utilizing the concentration polarization effect

This study develops a microfluidic device comprising two microchannels connected by a nanochannel in which the sample is concentrated via an ionic depletion effect. Using Rhodamine 6G dye for visualization purposes, it is shown that through an appropriate manipulation of the external potentials applied to the reservoirs of the device, an ionic depletion region with an electrical conductivity around 50 times lower than that of the buffer solution can be induced on the anodic side of the nanochannel. Furthermore, via an appropriate time-based switching of the external electrical potentials, the sample species can be concentrated close to the conductivity ratio within an interval of 1 min. Finally, it is shown that by varying the configuration of the electrical potentials applied to the device reservoirs, the concentrated sample can be delivered either to a single outlet reservoir or to multiple reservoirs.

Electrokinetically Based Approach for Single-Nucleotide Polymorphism Discrimination Using a Microfluidic Device

In this work, we describe and implement an electrokinetic approach for single-nucleotide polymorphism (SNP) discrimination using a PDMS/glass-based microfluidic chip. The technique takes advantage of precise control of the coupled thermal (Joule heating), shear (electroosmosis), and electrical (electrophoresis) energies present at an array of probes afforded by the application of external electrical potentials. Temperature controllers and embedded thermal devices are not required. The chips can be easily and inexpensively fabricated using standard microarray printing methods combined with soft-lithography patterned PDMS fluidics, making these systems easily adaptable to applications using higher density arrays. Extensive numerical simulations of the coupled flow and thermal properties and microscale thermometry experiments are described and used to characterize the in-channel conditions. It was found that optimal conditions for SNP detection occur at a lower temperature on-chip than for typical microarray experiments, thereby revealing the importance of the electrical and shear forces to the overall process. To demonstrate the clinical utility of the technique, the detection of single-base pair mutations in the survival motor neuron gene, associated with the childhood disease spinal muscular atrophy, is conducted.

Ferroelectric Space Charge Non-Destructive Read-Out memory

Abstract The Ferroelectric Space Charge (FESC) Memory is a technique to achieve Non-Destructive Read-Out (NDRO) of a ferroelectric memory that employs standard metal-ferroelectric-metal memory capacitors. The NDRO technique allows the polarization state of the capacitor to be read without altering the polarization. This provides the advantage that the memory capacitor is not subjected to the destructive read/rewrite cycle commonly employed in ferroelectric memories, so the lifetime of the device is limited only by the number of times the memory is written. In addition, the NDRO avoids the period of data volatility in the time interval between the read pulse and the subsequent rewrite of the data. The FESC NDRO approach utilizes changes in the dielectric response of the ferroelectric due to interactions between the internal space charges, the spontaneous polarization, and internal and external electrical potentials. The NDRO is implemented entirely in circuitry and does not require specialized ferroelectri...

Derivative Hartree–Fock approach to molecular Sternheimer shielding. Calculation of intermolecular influence on nuclear quadrupole coupling

Molecular Sternheimer shielding constants, γ, the proportionality constants relating the electric field gradient at a quadrupolar nucleus to an external electric field gradient are usually introduced phenomenologically. In this report, we take a comprehensive view of the sensitivity of the electric field gradient at a nucleus to arbitrary external electrical potentials and we show how the response can be obtained from analytically determined properties via derivative Hartree–Fock theory. From application of this ab initio technique, values have been obtained for the first and second order changes in nuclear quadrupole coupling with respect to external fields and field gradients, as well as nearby ideal multipole moments, for HCN and HCl. These values have been used to evaluate the change in the nuclear quadrupole coupling for several weakly bound complexes and to provide a nonempirical approach to relative effects on Sternheimer shielding. In weak molecular complexes, the effect of uniform fields can be as sizable as the effect of external field gradients in the overall change in nuclear quadrupole coupling, and so the underlying issue of convergence of multipolar expansions is considered over a range of geometries. This is important for structural interpretations of both nuclear magnetic resonance (NMR) and microwave data, and a simple formula, representing a practical point of truncation, is presented for quadrupole coupling analysis.

Doping superlattices ("n-i-p-i crystals")

Semiconductors with doing superlattices exhibit a number of unique features by which they differ from uniform bulk crystals as well as from semiconductors with a compositional superlattice. The properties which make them particularly appealing as a new kind of semiconductor are tunability of carrier concentration, bandgap, two-dimensional subband structure, and recombination lifetimes, in combination with an enormous flexibility in tailoring. Moreover, the choice of host materials is not restricted by interface- or lattice-matching problems. The possibility of varying conductivity, absorption coefficient, optical gain, and luminescence spectra by light or external electrical potentials implies new concepts for photodetectors, tunable light sources, optical amplifiers, and modulators. The long recombination lifetimes result in large low-power nonlinearities of the optical absorption coefficient and the refractive index. These properties offer applications for saturable absorbers and bistable optical devices. In this paper the basic concept of doping superlattices and experiments which have provided its verification will be reviewed first. New physical phenomena and possible device applications will then be discussed. Finally, we will report some recent results of extensions of the concept to "hetero n-i-p-i's," obtained by periodic modulation of composition superimposed on the periodic n-i-p-i doping profile.

Surface charge on polymeric implants and calcified tissues: interfacial implications.

Samples of human bone, dentin, and enamel were analyzed through the technique known as thermally stimulated discharge (TSD). It is possible through this technique to detect current flow resulting from appearance or loss of net polarization in a material. Samples of freshly extracted tissue give rise to well-defined TSD current maximal without having been exposed to external electrical potentials. Calculation of activation energies for these currents and their thermal range suggests the involvement of collagen denaturation in the loss of appearance of a net surface charge on bone and dentin surfaces. In the case of enamel samples, TSD current maxima are possibly the result of dipolar alignment in water or biopolymers by surface charges in the mineral phase. Interfacial implications of surface charge were studied through the measurement of adhesive strength in dentin/acrylic polymer joints. Enhancement of joint strength by a factor of two or higher was observed when powder particles of the experimental adhesive carried externally induced surface charge. It is hypothesized that electrostatic coupling between polarization domains on the tissue surface and the setting implant improves wetting and produces stronger interfaces.

256 - Charge Transfer across a Redox Membrane

Transport of electrons and of protons mediated by a water-insoluble redox system in a bilayer lipid membrane has been considered. The ratio of the electron to proton transport is shown to be a function of the ratio of the charged to neutral components of the membrane redox system. Only the charged redox components are directly affected by external electrical potentials, but their fluxes are then coupled with the fluxes of the neutral components. Even the neutral transport of electrons + protons across the bilayer membrane can give rise to a diffusion potential in the unstirred layers.

Earth Resistivity as Affected by the Presence of Underground Water

Resistance to the passage of a current of electricity is a property of all inert materials, including metals, ores, rocks, soil and the so-called nonconductors or insulators. When a convenient unit volume is considered, usually the cubic centimeter, this property is known as specific resistance or resistivity. The unit of resistivity is the ohm, which is the resistance offered by a column of mercury 106.3 cm. long, weighing 14,4521 gm. at 0?C. Reciprocal terms corresponding to resistivity and resistance are conductivity and conductance. It is considered at the present time that degree of conductivity is dependent upon the number of free elections drifting about within a material when it is under normal temperature conditions and unaffected by external electrical fields or potentials. Good conductors possess a large number of free electrons, while poor conductors have few, and those materials of such low conductivity as to be classed as insulators have almost no unattached electrons under normal conditions. Much difficulty arises in determining the resistivity of different kinds of rock and soils and there has been considerable variation in the results of tests made at different times and places, probably largely due to variations in moisture content as well as to less important differences in the exact chemical composition of the samples taken. In their work entitled Applied Geophysics, A. S. Eve and D. A. Keys give some interesting values of resistivity for certain types of rocks, soils and minerals as follows: Ohms per cubic cm. Granite 109 to 1011 Limestone 6.8 x104 Sandstone 5.0 to 100 x 109 Coal ...... 109 to 1017