Localized generation

When there is a fault in the local generating area (Figure 22.10(a)) the return path will be through the grounded neutral of the generator. The switchyard s other remote power sources may also contribute to... 

The use of ultrasonic (US) radiation (typical range 20 to 850 kHz) to accelerate Diels-Alder reactions is undergoing continuous expansion. There is a parallelism between the ultrasonic and high pressure-assisted reactions. Ultrasonic radiations induce cavitation, that is, the formation and the collapse of microbubbles inside the liquid phase which is accompanied by the local generation of high temperature and high pressure [29]. Snyder and coworkers [30] published the first ultrasound-assisted Diels-Alder reactions that involved the cycloadditions of o-quinone 37 with appropriate dienes 38 to synthesize abietanoid diterpenes A-C (Scheme 4.7) isolated from the traditional Chinese medicine, Dan Shen, prepared from the roots of Salvia miltiorrhiza Bunge. 

While the majority of attention has focused on peptides contained within the nervous system, two other important methods for delivering peptides to the vicinity of the mast cell have been established (1) peptides produced and secreted by other cells of inflammation that may affect mast-cell function and (2) the local generation of mast-cell-active peptides by secreted enzymes acting on circulating protein precursors. Examples of the former include several, as yet ill-defined, peptide factors and cationic proteins from other immunocompetent cells [66-69], defined lymphokines such as the interleukin-1 [70] and interleukin-3 [71], and tumour necrosis factor [70], Examples of the latter include bradykinin [72] and a recently identified peptide produced by the action of acid proteinases on albumin [73, 74]. 

Figure 4.8. Hypothesis for the local generation of mast-cell-stimulating peptides by the action of neutrophil-derived enzymes on albumin. Initial stimulation of the mast cell by any of a variety of agents causes the release of preformed histamine (H) neutrophil and eosinophil chemotactic factors (NCF, ECF) and enzymes and the de novo synthesis of prostaglandins (PG) and leukotrienes (LT). These agents increase vascular permeability and vessel diameter. As a result, albumin and later neutrophils (PMN) enter the tissue space where the latter undergo phagocytosis and the secretion of proteolytic enzymes to the extracellular space where they act on albumin to generate NRP (neurotensin-related peptide) and HRP (histamine-releasing peptide). These newly formed peptides then act as a second stimulus to the mast cell. In addition NRP and HRP may affect other immunocompetent celt such as monocytes, macrophages or eosinophils.

It is through the local generation of eicosanoids that intrauterine contraceptive devices are effective, since they stimulate production of prostaglandins by the myometrium which increases its contractility, preventing implantation. 

Policy Studies on infrastructure considerations and transition management activities include (a) Fuel Cell RD D activities (b) SOFC and PEMFC cells, stacks, systems are being developed in relation to local generation (c) Systems field testing is being undertaken by Siemens-Westinghouse, Sulzer, and Plug-Power. 

R D on SOFC and PEM, stacks and systems in relation to local generation, CHP and u-CHP on the basis of natural gas and hydrogen in the future (ECN, NedStack, Hexion). 

With practical, low- to medium-capacity generating schemes, local generating stations for isolated and sparse geographical areas can conserve major costs in installing and maintaining long-power transmission lines. 

Applications have been reported for photoelectrochemical experiments, for example, splitting of water [11], local generation of photoelectrodes by spatially selective laser excitation [12], and steady-state electrochemiluminescence at a band electrode array [13,14]. Band electrodes prepared from very thin films approaching molecular dimensions have been used to assess the limits of theory describing electrode kinetics at ultramicroelectrodes [9]. Spectroelectrochemical applications have been extensively reviewed [1], In an intriguing approach, thin, discontinuous metal films have been prepared on a transparent semiconductor substrate they are essentially transparent under conditions in which a continuous metal film containing the same quantity of metal would be expected to substantially absorb [15]. 

Matsuoka I, Ohkubo S (2004) ATP- and adenosine-mediated signaling in the central nervous system adenosine receptor activation by ATP through rapid and localized generation of adenosine by ecto-nucleotidases. J Pharmacol Sci 94 95-9... 

In certain physical situations the quantity R is indestructible or uncreatable It can neither be generated nor destroyed locally. In such circumstances dR/dt, the rate of local generation or annihilation of R, must necessarily vanish. For this special case... 

Ultrasound was reported to promote Diels-Alder reactions as well as improve their regioselectivity similarly to high pressure, but much more conveniently (Scheme 56, Table 7). Comparison of entries 2/3 indicates the similarity of the yields and product ratios (242)/(243), obtained at 10 kbar (entry 2) and on sonication (entry 3). The latter were attributed to the implosion of the ultrasound-induced cavities which locally generate high pressures and temperatures (up to 1 kbar and 5000 K). Deacetalization of the major aromatized regioisomer (242) gave the natural product tanshindiol B. 

---