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We propose a conductively coupled terahertz metallic metamaterial exhibiting analog of electromagnetically induced transparency (EIT), in which the bright and dark mode antennae interact via surface currents rather than near-field coupling. Aluminum foil, which is very cheap and often used in food package, is used to fabricate our metamaterials. Thus, our metamaterials are also flexible metamaterials. In our design, aluminum bar resonators and aluminum split ring resonators (SRRs) are connected (rather than separated) in the form of a fork-shaped structure. We conduct a numerical simulation and an experiment to analyze the mechanism of the proposed metamaterial. The surface current due to LSP resonance (bright mode) flows along different paths, and a potential difference is generated at the split gaps of the SRRs. Thus, an LC resonance (dark mode) is induced, and the bright mode is suppressed, resulting in EIT. The EIT-like phenomenon exhibited by the metamaterial is induced by surface conducting currents, which may provide new ideas for the design of EIT metamaterials. Moreover, the process of fabricating microstructures on flexible substrates can provide a reference for producing flexible microstructures in the future.

In electro-thermal-compliant (ETC) actuators, a voltage is applied to the electrical terminals of the device. The potential difference induces currents to flow throughout the device, which cause the temperature to rise due to Joule heating. ETC actuators use the resulting thermal expansion to create motion. Typically, they also have some method of amplifying these small displacements into useable motion.

The electroencephalogram (EEG) is a non-invasive measure of brain electrical activity recorded as changes in potential difference between points on the human scalp. Because of volume conduction through cerebrospinal fluid, skull and scalp, EEG data collected from any point on the scalp includes activity from processes occurring within a large brain volume.

Ca2+ entry is needed for muscle to contract. This was originally reported by RINGER [1] in 1883 and later reinforced by showing that Ca2+ injection by means of a micropipette brings about a local contracture. The existence of a permeability for Ca2+ in excitable cells was recognized nearly 40 years ago in crab muscle fibres just after the proposal of the ionic theory by HODGKIN and HUXLEY [2]. Moreover, (in 1956) Co-RABOEUF and OTSUKA [3] claimed that a guinea pig ventricle heart cell can generate action potentials in the complete absense of external Na+. In 1964, NIEDERGERKE and ORKAND [4] reported that the amplitude of the action potential overshoot varied as a function of [Ca2+]out as if the membrane behaves like a Ca2+-electrode. Direct evidence of Ca2+ entry was given by the demonstration under potential difference clamping that a current could be carried by Ca2+ and further increased by adrenaline [5]. Ca2+ entry is now easily observed with the use of ion-sensitive fluorescence indicators (TSIEN [6]).

The general features of electrical breakdown between two electrodes in a liquid have been known for decades. When breakdown occurs, a flash of light is emitted, an acoustic signal is emitted, the potential difference between the electrodes decreases rapidly, and the current flowing between the electrodes increases rapidly. The continuing development of light sources, high-speed cameras, and high-speed electronic measuring ’ systems have made it possible to study the breakdown process in increasing detail. This lecture summarizes some of the results obtained using these various measurement techniques to investigate electrical breakdown in liquids under pulsed voltage.

Electromagnetic fields associated with surface cracks in metals have been widely studied in recent years in connection with eddy current and a.c. field techniques for detecting and sizing fatigue and corrosion cracks. In our own work, studies have been made of thin-skin fields for cracks of various plan forms using unfolded field techniques 1,2,3, and of the two-dimensional crack (i.e. the large aspect ratio crack) in a semi-infinite material when the ratio of crack depth to skin depth is arbitrary4,5. These studies were prompted by the need to obtain accurate interpretation of surface probe readings from an a.c. potential difference instrument which was developed at University College London and is marketed under the name Crack Microgauge. The instrument was originally designed to operate at a frequency of 5.6 kHz, but further development has produced a dual-frequency version with a second and lower frequency of 560 Hz. This enables an operator to make a choice of skin depth § to suit his particular test material and crack geometry. A reduction in the frequency has the effect of increasing § which can be practically useful in several ways. For example in examining for subsurface flaws it is necessary to increase the penetration of the field into the material so that it reaches to the depth of the flaw. A further application which provides the motivation for the present paper is to the situation where a crack occurs on one face of a plate of known thickness. There are many instances, for example in investigating structures fabricated from sheet material, or in the examination of pipe-work, where it would be useful to be able to detect and measure cracks on the inside surface by testing on the outside. Testing from the blind side in this manner evidently requires that the frequency should be low enough for the skin depth to be comparable with the plate thickness. In this paper our main aim is to report the results of a theoretical and experimental study of the field in a plate which has a two-dimensional normal crack on one face. The theory allows arbitrary values of the ratio of skin depth § to plate thickness b. In particular we examine the signal on the face opposite to the crack which would enable the presence of the crack to be detected.

Crystal growth is strongly influenced by the configuration of the interface between the crystal and the vapour phases. The relation between the growth rate and the interfacial configuration was investigated Chui and Weeks1,2 by means of linear-response theory and by using the Kosterlitz renormalization-group (RG) method. Above the roughening temperature T, where the interface is rough, the growth rate R is found to be proportional to the chemical potential difference Ay, whereas below T, where the interface is flat, the crystal is found not to grow. A puzzling feature of their results is that the ratio R/Ay for ∆µ → 0 is finite on approaching TR from above, whereas it remains zero on approaching TR from below. Interesting unanswered questions concern the extent of the non-growing region (in Ay) below T, and the nature of the growth for larger ∆µ.

A potential difference (pd) between maternal and fetal circulations created by active transport of electrolytes by the placenta would be important not only for the actively transported species themselves, but also for the transfer of passively distributed charged molecules. In several species, it is possible to measure a pd between catheters placed in maternal and fetal vessels. It is possible that this maternofetal pd is a result of active electrolyte transport by the placenta. However, the recorded pd’s have a wide range, for example in the sheep it is 34 mV, fetus negative relative to mother (Weedon et al., 1978), whereas in the rat it is 14 mV, fetus positive (Mellor, 1969). Considerable doubt is shed on the placental basis of this pd by at least two lines of evidence. Firstly, there appears to be no relationship between the magnitude and polarity of the pd and the type of placenta, e.g., the guinea pig which has a relatively permeable (Hedley and Bradbury, 1980) haemochorial placenta demonstrates a pd of 18 mV, fetus negative (Mellor, 1969) more similar to that of the sheep, which has a relatively impermeable (Boyd et al., 1976) epitheliochorial type of placenta than to the term human (O mV, Mellor et al., 1969). Further evidence against the placenta being the site of pd generation comes from Binder et al. (1978) and Thornburg et al. (1979) who found in the guinea pig and sheep, respectively, that the steady-state concentration ratio between maternal and fetal plasmas of exogenous ions injected into the mother was consistent with a near zero transplacental pd. They suggest that the maternofetal pd is generated at a site outside of the placental exchange area.

The vaginal epithelium in women is a stratified epithelium with no glands (Figure 1). It is constantly renewed from the mitosis in the basal layer, with cellular exfoliation from the surface.

The nature of the current-induced transition from perfect superconductivity to full recovery of the normal state has been of recurrent interest since the earliest days of H. Kamerlingh Onnes, who reported (1913): “At the end of the superconductive wire there is no potential difference as long as the current remains below the threshhold value for this wire. As soon as this value is surpassed potential differences originate and the wire by a process that is not quite cleared up obtains ordinary resistance.” Such a transition is inherently a nonequilibrium phenomenon, and given what we have learned from the preceding chapters it should be possible to see what aspects of this process have and have not yet been cleared up.

Bioelectric phenomena have been observed in many absorptive epithelia and are related to the transport activities and permeability characteristics of these tissues. The intestine is an epithelial tissue which is involved in the net transfer of both solutes and water from its lumen, and its electrical activity can be related to its absorptive functions. Early work in the frog demonstrated the existence of a small potential difference across the wall of the small intestine [1, 2]. A somewhat larger transmural electrical gradient was obtained from amphibian large intestine [3, 4]. However, a more intensive study of the, bioelectric properties of the intestine did not really begin until the 1960’s when a number of groups initiated comprehensive investigations into the nature of the electrical activity and its relationship to the absorptive functions of the various regions of the intestine.

Many aspects of the equilibrium and growth kinetics of crystals have been studied on the solid on solid (SOS) model. In order to set up the kinetic equations of crystal growth the cluster approximation has been often used. As the approximation proceeds from the Bragg-Williams (point)1 approximation to the pair approximation2, the region of unphysical metastable state at low temperatures for small driving force Δμ/kT is considerably reduced. Here Δμ is the chemical potential difference between vapor and solid and T is the absolute temperature. However, there can be seen still a wide non-growth region compared with the Monte Carlo simulation result3.

Gouy1 and Chapman2 gave equations for the excess net charge in a solution per unit area of an electrode as a function of the metal-solution potential difference, assuming only electrical interaction with the electrode, and for point ions. The corresponding equation that arises for the diffuse-layer capacitance is $$C_{{\text{2 - b}}} = \left( {\frac{{z^2 e_0^2 n\varepsilon }} {{2\pi kT}}} \right)^{1/2} \cosh \frac{{ze_0 \varphi _{2 - b} }} {{2kT}}$$ (1.1) φ2−b is the potential of the layer of ions in the outer Helmholtz plane (OHP) with respect to that of the solution, in which the concentration is n ions/cm3.

In order to use solid materials most effectively in solid electrolyte applications, they need to be characterized as fully as is practical. Here, one useful method of electrical response characterization will be discussed: measurement of the response when a small-signal sinusoidal potential difference is applied across a sample. A great deal more can be learned from the frequency and temperature dependence of the resulting impedance than from ordinary DC or single-frequency AC conductance measurements alone.

Although CCD has been applied to the separation and analysis of a number of different cell types, there has been little attempt to quantitate the resolving power of this technique. In this study, the resolving power of CCD has been examined using neuraminidase-treated and untreated human erythrocytes as model cells. By treating erythrocytes with different concentrations of neuraminidase, cell populations differing in their sialic acid content, and hence their surface negative charge, were obtained. The ability of CCD to resolve neuraminidase-treated and control erythrocytes, exhibiting increasingly similar amounts of surface sialic acid, was determined using 30-transfer CCD and a phase system of high electrostatic potential difference between the phases (ΔΨ). The limit of resolution of CCD was expressed in terms of the μg difference in sialic acid content between the two red cell populations which were just resolved.

So far the bioelectric potential differences, commonly detectable across membranes and relevant to the study of ion fluxes, have hardly been mentioned in this book. One reason is that many students get confused by a kind of ‘chicken and egg’ argument about whether the potential difference’ is set up and results in the ion flux, or alternatively whether a biochemically driven ion flux results in a p.d. Since a rational explanation of the basis of ion fluxes can be given without reference to this question it has so far been avoided, and the reader might be tempted to conclude that the second alternative is nearer the truth. But this conclusion is not really justified, and may arise from a misunderstanding about electrochemistry: any separation of electrical and chemical aspects of this subject is arbitrary.

The plate is infinite in extent and bounded by two parallel planes located at, say, x 2 ± h, as shown in Fig. 10. For our purposes, both faces of the plate may (or may not) be completely coated with electrodes which are infinitesimally thin. Since the electrodes are infinitesimally thin, all possible mechanical effects may be ignored. When the electrodes are there we shall assume that an alternating potential difference is applied to them.