Electrically responsive

Benitez J J, Centeno M A, Merdrignac O M, Guyader J, Laurent Y and Odriozola J A 1995 DRIFTS chamber tor in situ and simultaneous study of infrared and electrical response of sensors Appl. Spectrosc. 49 1094-6... 

Researchers at the MoneU Center (Philadelphia, Pennsylvania) are using a variety of electrophysical and biochemical techniques to characterize the ionic currents produced in taste and olfactory receptor cells by chemical stimuli. These studies are concerned with the identification and pharmacology of the active ion channels and mode of production. One of the techniques employed by the MoneU researchers is that of "patch clamp." This method aUows for the study of the electrical properties of smaU patches of the ceU membrane. The program at MoneU has determined that odors stimulate intraceUular enzymes to produce cycUc adenosine 3, 5 -monophosphate (cAMP). This production of cAMP promotes opening of the ion channel, aUowing cations to enter and excite the ceU. MoneU s future studies wiU focus on the connection of cAMP, and the production of the electrical response to the brain. The patch clamp technique also may be a method to study the specificity of receptor ceUs to different odors, as weU as the adaptation to prolonged stimulation (3). 

Excitability. Excitabihty refers to electrical responsiveness of the heart to various stimuli by the generation of local excitatory currents, action potentials, or fibrillation. 

Perhaps the most dramatic exception to the perfectly elastic, perfectly plastic materials response is encountered in several brittle, refractory materials that show behaviors indicative of an isotropic compression state above their Hugoniot elastic limits. Upon yielding, these materials exhibit a loss of shear strength. Such behavior was first observed from piezoelectric response measurements of quartz by Neilson and Benedick [62N01]. The electrical response observations were later confirmed in mechanical response measurements of Waekerle [62W01] and Fowles [61F01]. 

Fig. 5.5. The electrical response of piezoelectric polymers under shock loading is studied experimentally by placing the thin PVDF element on the impact surface of a standard target, either the polymer, Kel F, z-cut quartz, or z-cut sapphire. The im-pactor is typically of the same material. The current pulse is recorded on transient digitizers with frequency responses from 250 to 1000 MHz.

In this book those ferroelectric solids that respond to shock compression in a purely piezoelectric mode such as lithium niobate and PVDF are considered piezoelectrics. As was the case for piezoelectrics, the pioneering work in this area was carried out by Neilson [57A01]. Unlike piezoelectrics, our knowledge of the response of ferroelectric solids to shock compression is in sharp contrast to that of piezoelectric solids. The electrical properties of several piezoelectric crystals are known in quantitative detail within the elastic range and semiquantitatively in the high stress range. The electrical responses of ferroelectrics are poorly characterized under shock compression and it is difficult to determine properties as such. It is not certain that the relative contributions of dominant physical phenomena have been correctly identified, and detailed, quantitative materials descriptions are not available. 

From the mechanical viewpoint, ferroelectrics exhibit unsteady, evolving waves at low stresses. Waves typical of well defined mechanical yielding are not observed. Such behavior is sensitive to the electrical boundary conditions, indicating that electromechanical coupling has a strong influence. Without representative mechanical behavior, it is not possible to quantitatively define the stress and volume compression states exciting a particular electrical response. 

The cells that contain the specimen and environment for stress-corrosion tests frequently need to be more than a vessel made in some substance, usually glass, that is inert to the environment and which produces no electrical response upon the test specimen. Where cracking is initiated at surfaces through which heat transfer occurs it may be necessary to design a cell in... 

In the early 1980s it beeame elear that metal electrons play an important role in the electrical response at metal-eleetrolyte interfaees. Different aspects have been extensively reviewed [23-27], Here we only briefly diseuss the problem of negative capacitance, and how it arose in these studies. 

III. ELECTRICAL RESPONSE OF THE LIQUID MEMBRANE TO DRUGS A. Hypnotics... 

We only consider static response properties in this chapter, which arise from fixed external field. Their dynamic counterparts describe the response to an oscillating electric field of electromagnetic radiation and are of great importance in the context of non-linear optics. As an entry point to the treatment of frequency-dependent electric response properties in the domain of time-dependent DFT we recommend the studies by van Gisbergen, Snijders, and Baerends, 1998a and 1998b. 

Evoked potential testing A procedure in which sensory nerve pathways are stimulated and the time lapse to electrical response in the corresponding area of the brain is measured. 

Chelli R, Procacci P, Righini R, Califano S (1999) Electrical response in chemical potential equalization schemes. J Chem Phys 111 (18) 8569—8575... 

Grinvald A, Fine A, Farber IC, Hildesheim R (1983) Fluorescence monitoring of electrical responses from small neurons and their processes. Biophys J 42(2) 195-198... 

After a brief discussion of fundamentals of charge transport mechanisms, this chapter summarizes and discusses the most significant results obtained by using different junctions and in particular LAJs. In order to facilitate a systematic discussion, we make a functional distinction between non-active and active junctions we will refer to active junctions as those aimed at changing the electrical response by means of an external stimulus acting in situ to modify the molecular electronic structure non-active junctions are those used to measure and compare the electrical properties inherent to the different electronic structure of incorporated molecules, without any modification induced by an external signal. 

Fig. 13 Schematic representation of a photo-active molecular junction containing DAE-based SAM sandwiched between a semitransparent Au bottom electrode and an SAM/Hg-drop top electrode. The electrical response of the junction is measured upon irradiation at different wavelengths through the semitransparent bottom electrode...

Second, in designing new molecule-based electronic devices, one of the major goals is the precise control of the current flowing between the terminals. Electrochemical molecular junctions allow for control of the potentials of the electrodes with respect to the redox potential of incorporated redox-active molecules with well-defined, accessible, tunable energy states. These junctions represent unique systems able to predict precisely at which applied potential the current flow will take off. Even though the presence of a liquid electrolyte represents a detriment towards possible applications, they provide the concepts for designing molecular devices that mimic electronic functions and control electrical responses. 

Alternative second-messenger pathways may be at work in olfactory transduction. The role of cAMP in olfactory transduction is well established. Are there alternative pathways, such as those involving phospholipids and Ca2+ Several groups have reported that certain odorants can elicit an increase in the phosphoinositde second messenger inositol 1,4,5,-trisphosphate (IP3) (Ch. 20). However, there is no clear evidence that IP3 directly mediates an electrical response in OSNs, nor is there a clear rationale for two parallel excitatory odor transduction cascades. However, more recent data support the idea that phos-phoinositides or enzymes related to their metabolism may play a modulatory role, shaping the OSN output by... 

Hair cells are the sensory cells of the auditory and vestibular systems. Hair cells are the sensory cells of the internal ear, essential for the senses of sound and balance. The hair cell s transduction apparatus, the molecular machinery that converts forces and displacements into electrical responses, can respond to mechanical stimuli of less than 1 nm in amplitude, and of tens or even hundreds of kilohertz in frequency. Indeed, our hearing is ultimately limited by Brownian motion of water molecules impinging on the transduction apparatus. 

Hormonal actions on target neurons are classified in terms of cellular mechanisms of action. Hormones act either via cell-surface or intracellular receptors. Peptide hormones and amino-acid derivatives, such as epinephrine, act on cell-surface receptors that do such things as open ion-channels, cause rapid electrical responses and facilitate exocytosis of hormones or neurotransmitters. Alternatively, they activate second-messenger systems at the cell membrane, such as those involving cAMP, Ca2+/ calmodulin or phosphoinositides (see Chs 20 and 24), which leads to phosphorylation of proteins inside various parts of the target cell (Fig. 52-2A). Steroid hormones and thyroid hormone, on the other hand, act on intracellular receptors in cell nuclei to regulate gene expression and protein synthesis (Fig. 52-2B). Steroid hormones can also affect cell-surface events via receptors at or near the cell surface. 

H.C.F. Martens and H.B. Brom, Frequency-dependent electrical response of holes in poly(/j-phcnylcnc vinylene), Phys. Rev. B, 60 R8489-R8492, 1999. 

Although a family of OgS - Jig8 values are allowed under Equation 7 the actual equilibrium state of the oxide/solution interface will be determined by the dissociation of the surface groups and the properties of the electrolyte or the diffuse double layer near the surface. For surfaces that develop surface charges by different mechanisms such as for semiconductor, there will be an equation of state or charge-potential relationship that is analogous to Equation 7 which characterizes the electrical response of the surface. 

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