Charge pinned

In a light-scattering study of dihydroxy bile salts, Kratohvil and Del-licolli (120) estimated the fractional micellar charge, pjn, of NaTDC in 0.15 M NaCl from Debye plots. Here p represents the number of fundamental charges per micelle and n the number of monomer ions per micelle. Since m is the number of counterions bound to a micelle, then pin is equal to 1 — in/n. The fractional micellar charge pin was 0.29 in 0.15 M NaCl. From the present data pin for zero excess counterion (i.e., in water) concentration is 0.77. 

Zotti, G., Schiavon, G., Berlin, A., and Pagani, G., Anion effects on conductivity of isomorphous polypyrrole. Charge pinning by nucleophilic anions, Synth. Met., 40, 309-316 (1991). 

The most significant commercial product is barium titanate, BaTiO, used to produce the ceramic capacitors found in almost all electronic products. As electronic circuitry has been rniniaturized, demand has increased for capacitors that can store a high amount of charge in a relatively small volume. This demand led to the development of highly efficient multilayer ceramic capacitors. In these devices, several layers of ceramic, from 25—50 ]lni in thickness, are separated by even thinner layers of electrode metal. Each layer must be dense, free of pin-holes and flaws, and ideally consist of several uniform grains of fired ceramic. Manufacturers are trying to reduce the layer thickness to 10—12 ]lni. Conventionally prepared ceramic powders cannot meet the rigorous demands of these appHcations, therefore an emphasis has been placed on production of advanced powders by hydrothermal synthesis and other methods. 

Low resistivity can sometimes be a problem, if the resistivity is below lO" n-cm, the collected particles are so conductive that their charges leak to ground faster than they are replenished bv the corona. The particles are no longer electrostatically pinned to the plate, and... 

An alternating-current electrode svstern referred to in the indiisti v as a wiper is often installed in the nonconductor product-collection section behind each drum. The function of the wiper is to use an ac corona to neutralize the charge on the nonconductor particles pinned... 

Fig. 4.7. A semiconductor detector operated as a pin diode with a reverse voltage or bias. An incident X-ray photon ultimately produces a series of electron-hole pairs. They are "swept out" by the bias field of-500 V- electrons in the direction ofthe n-layer holes in the direction ofthe p-layer. Thus, a small charge pulse is produced after [4.21],...

Parker [55] studied the IN properties of MEH-PPV sandwiched between various low-and high work-function materials. He proposed a model for such photodiodes, where the charge carriers are transported in a rigid band model. Electrons and holes can tunnel into or leave the polymer when the applied field tilts the polymer bands so that the tunnel barriers can be overcome. It must be noted that a rigid band model is only appropriate for very low intrinsic carrier concentrations in MEH-PPV. Capacitance-voltage measurements for these devices indicated an upper limit for the dark carrier concentration of 1014 cm"3. Further measurements of the built in fields of MEH-PPV sandwiched between metal electrodes are in agreement with the results found by Parker. Electro absorption measurements [56, 57] showed that various metals did not introduce interface states in the single-particle gap of the polymer that pins the Schottky contact. Of course this does not imply that the metal and the polymer do not interact [58, 59] but these interactions do not pin the Schottky barrier. 

What has been described so far constitutes only one half of the friction primer, ie, the main charge, contained in a cylindrical cup. Centrally located in the K chlorate mixt was a loop of braided wire, coated with red P (90%) and dried shellac (10%). Any mixt of red P with K. chlorate was, and still is, very sensitive, hazardous, and unpredictable. There is ample reason to understand why friction primers were abandoned and replaced with spring-actuated firing pins to fire percussion primers and carry the sequence thru a suitable expl train... 

Singh P, Singh R, Gale R, Rajeshwar K, DuBow J (1980) Surface charge and specific ion adsorption effects in photoelectrochemical devices. J Appl Phys 51 6286-6291 Bard AJ, Bocarsly AB, Pan ERF, Walton EG, Wrighton MS (1980) The concept of Fermi level pinning at semiconductor/liquid junctions. Consequences for energy conversion efficiency and selection of useful solution redox couples in solar devices. J Am Chem Soc 102 3671-3677... 

To use this device, the blasting cap may be inserted directly into the explosive or it may be connected to the explosive with primacord. In either case the firing device should be securely attached to a solid object. Run the trip wire from a fixed location to the cotter pin, leaving some slack in the line. A pull on the trip wire will remove the cotter pin, initiating the charge. 

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