Fuses selection

Figure 12.34 Fuse selection chart for 6.6 kV system for a motor with run-up time not exceeding 60 seconds...

Protein transport between intracellular compartments is mediated by a mechanism that is well-conserved among all eukaryotes, from yeast to man. The transport mechanism involves carrier vesicles that bud from one organelle and fuse selectively to another. Specialized proteins are required for vesicle transport, docking, and fusion, and they have been generically named SNAREs (an acronym for soluble N-ethylma-leimide-sensitive fusion attachment protein receptor). SNAREs have been divided into those associated with the vesicle (termed v-SNAREs), and those associated with the target (termed t-SNAREs). The key protein, which led to the discovery of SNAREs was NSF, an ATPase found ubiquitously in all cells, and involved in numerous intracellular transport events. The subsequent identification of soluble proteins stably bound to NSF, the so-called SNARE complex, led to the formulation of the SNARE hypothesis, which posits that all intracellular fusion events are mediated by SNAREs (Rothman, 2002). 

Crystallised sodium sulphide NajS,9HjO is very deliquescent, and only a sample which has been kept in a tightly-stoppered bottle should be used crystals as dry as possible should be selected. Altemativelj, an equivalent amount of analysed fused sodium sulphide may be employed this dis.solves somewhat more slowly in alcohol. 

In MeOH, l,4-dimethoxy-2-cyclohexene (379) is obtainejl from 1,3-cydo-hexadiene[315]. Acetoxylation and the intramolecular alkoxylation took place in the synthesis of the naturally occurring tetrahydrofuran derivative 380 and is another example of the selective introduction of different nucleo-philes[316]. In intramolecular 1,4-oxyacetoxylation to form the fused tetrahy-drofurans and tetrahydropyrans 381, cis addition takes place in the presence of a catalytic amount of LiCI, whereas the trans product is obtained in its absence[317]. The stereocontrolled oxaspirocyclization proceeds to afford the Irons product 382 in the presence of Li2C03 and the cis product in the presence of LiCl[ 318,319]. 

If there is a choice between components of the same size containing the same number and kind of heteroatoms, choose as the base component that one with the lower numbers for the heteroatoms before fusion. When a fusion position is occupied by a heteroatom, the names of the component rings to be fused are selected to contain the heteroatom. 

The aromatic core or framework of many aromatic compounds is relatively resistant to alkylperoxy radicals and inert under the usual autoxidation conditions (2). Consequentiy, even somewhat exotic aromatic acids are resistant to further oxidation this makes it possible to consider alkylaromatic LPO as a selective means of producing fine chemicals (206). Such products may include multifimctional aromatic acids, acids with fused rings, acids with rings linked by carbon—carbon bonds, or through ether, carbonyl, or other linkages (279—287). The products may even be phenoUc if the phenoUc hydroxyl is first esterified (288,289). 

In 1975, the first successful production of MAbs was reported (44). By fusing normal antibody-producing cells with a B-ceU tumor (myeloma), hybridoma cell lines resulted which produced antibodies having a specificity to only one deterrninant on an antigen ie, all the antibodies produced from the cell line are identical. These studies resulted in a standard approach to MAb production. In this approach, the hybridoma cells are produced in large quantities in culture and screened to select specific clones producing the desired MAb using an appropriate assay. The selected clones are then expanded in culture (or in animals), the cells are collected, and the MAbs are extracted and purified. 

The laser spray process uses a high power carbon dioxide laser focused onto the surface of the part to be metallized. A carrier gas such as belium blows metal particles into the path of the laser and onto the part. The laser melted particles may fuse to the surface, or may be incorporated into an aHoy in a molten surface up to 1-mm thick. The laser can be used for selective aHoying of the surface, for production of amorphous coatings, or for laser hardening. 

Interesting results have been obtained in intramolecular acylation reactions involving pyrrole and thiophene derivatives. A muscone synthesis involves selective intramolecular acylation at a vacant a-position (Scheme 18) (80JOC1906). In attempts to prepare 5,5-fused systems via intramolecular acylation reactions on to a jS-position of a thiophene or a pyrrole, in some cases ipso substitution occurs with the result that rearranged products are formed (Scheme 19) (82TH30200). 

A variety of 1-azirines, including the first fused derivatives, have been prepared by the selective irradiation at 350 nm of the appropriate vinyl azide precursors (68JA2869). 

The tube-to-tubesheet joint, how is it made Many use O rings to add another material to the selection process. Preference should be given to a fusing technique of similar material. 

Tube to tubesheet joints, a weakness of most nonmetallic units, are fused by special techniques that do not severely affect the chemical suitabihty of the unit. Some nonmetallics use Teflon or O rings that add an extra consideration to material selection. 

Check selection of fuses for the type of load and switching. Perhaps they are under-rated for the starting inrush current and its duration. For selection of fuse ratings see Section 12.10.4. 

Selection of the fuse ratings must be made on the following... 

Coordination of fuses with an overcurrent relay or any other overcurrcnt protective device The selection of the fuses should be such that ... 

In such cases it may ollen be possible to meet the requirement by selecting a higher frame size of MCB or MCCB, which inay possess a higher rupturing capacity also. If not, and to save on cost, one may provide HRC fuses for back-up protection. 

To make a proper selection of HRC fuses it is essential that the current-time characteristic curves for Ihe releases of the breaker and the fuses are available from their manufacturers. 

Consider four equally spread starts/hour. From the selection chart in Figure 12.34, select the characteristics B-B and determine the fuse rating as 350 A on the ordinate corresponding to a starting current of 924 A on 1he abscissa. 

Table 12.4 Selection table for switches, fuses, relays and cables for different sizes of LT motors...

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