Extrusion mechanism

Integral (or extruded). An aluminum outer tube from which fins have been formed by extrusion, mechanically bonded to an inner tube or liner. 

We have examined Ca2+ extrusion mechanisms and the SR in relaxation (Fig. 4). These data can be summarized as follows (Shmigol et al 1998b, 1999) ... 

The rate of decay of the [Ca2+] following carbachol stimulation was slowed when SERCA was inhibited by CPA, by > 50%. However, the decay of the Ca2+ transient was abolished if plasmalemmal extrusion mechanisms were inhibited. 

Thus in the uterus the SR contributes to the decay of the [Ca2+] transients but, acting alone, it cannot significantly reduce Ca2+. The conclusion reached is that the SR takes up Ca2+ and then releases it close to the plasmalemmal Ca2+ extrusion sites (i.e. the SR is acting in series with the surface membrane extrusion mechanisms). This translocation is thought to be mediated by the SR forming a superficial barrier in the narrow space between the SR and plasmalemma and the SR releasing the Ca2+ in a vectorial manner (van Breemen 1977). 

In summary, in the uterus where L-type Ca entry represents the most significant mechanism for elevating Ca2+], then it is necessary that surface membrane extrusion mechanisms exist to remove the Ca2+ gained by the cell. In the uterus this task is performed equally by the Na+/Ca2+ exchanger and the Ca-ATPase. However the SR contributes to this process by taking up Ca2+ and vectorially releasing it to the extrusion sites, to maximize their efficiency. 

Wray These are more pronounced than what we get with ryanodine. Whether this is to do with the time course, I m not sure. If extrusion mechanisms are more stimulated to a greater extent by faster or slower changes in Ca2+, then it may be difficult to compare. 

Wray The speed of the Ca2+ release seems to be important faster rises will stimulate these mechanisms better than slow ones. For example, if we put on CPA or thapsigargin, often we will see a substantial elevation of basal Ca2+, but it is quite slow. We don t see a corresponding rise of the basal level of force production in many of the tissues. It seems that there is a lot of Ca2+ there but the contractile machinery is not interested in it. It will presumably also be the case that extrusion mechanisms handle small, slow releases, and hence little or no contraction. 

The differences of the intrusion and extrusion mechanisms are the main factors, leading to the different pathways (hysteresis) of the branches in Fig. 1.16A. Furthermore, this effect causes the pore size distribution obtained from the intrusion curve to be incorrectly shifted towards smaller pore sizes. Unlike some inorganic materials of very regular pore structure (e.g. zeolites), permanently porous organic polymers consist of a very complex network of pores of different sizes connected to each other. Correction of these falsifications in the results described above is virtually impossible, since it implies a detailed understanding of the network. 

M. Fartasch, I. D. Bassakas, and T. L. Diepgen. Disturbed extrusion mechanism... 

The classic extrusion model gives insight into the screw extrusion mechanism and first-order estimates. For more accurate design equations, it is necessary to eliminate a long series of simplifying assumptions. These, in the order of significance are (a) the shear rate-dependent non-Newtonian viscosity (b) nonisothermal effects from both conduction and viscous dissipation and (c) geometrical factors such as curvature effects. Each of these... 

Figure 11 Tip-growth and extrusion mechanisms of carbon filament growth. (Ref. 58. Reproduced by permission of Elsevier)...

Fig. 10 The NICA system radial-screen extruder. (A) Assembled unit. (B) Dismantled to show extrusion mechanism. (C) Cross section indicating working principle.

Evidence for chloride accumulation and extrusion mechanisms were examined with putative inhibitors. Intracellular injection of ammonium ions, bathing the preparation in 4-acetamido-4,-isothiocyanatostilbene-2,2 -disulphonic acid (SITS), 4,4 -diisothiocyanato-stilbene-2,2 -disulphonic acid (DIDS), acetazolamide, furosemide, NH +, Zn + or Cu + were without effect on the reversal potential for GABA. The data obtained so far suggest that chloride-regulating mechanisms present in the cockroach are not sensitive to the inhibitors which block other invertebrate (15,16) or vertebrate (17) chloride pumps. 

A maleated ester of low density polyethylene, prepared by the reaction of LDPE and dibutyl maleate in solution, was blended with TPS by reactive extrusion. Mechanical properties of the blends were similar to those of the LDPE due to the compatibilization of these dissimilar components [75]. 

Benbow JJ, Oxley EW, Bridgwater J (1987) The Extrusion Mechanics of Pastes - the Influence of Paste Formulation on Extrusion Parameters. J Chem Eng Sci vol. 42 No 9 pp 2151-2162 Benbow JJ, Lawson TA, Oxley EW (1989) Prediction of Paste Extrusion Pressure. J Ceramic Bulletin vol. 68 No 10 pp 1821-1824 Benbow JJ, Jazayeri SH, Bridgewater J (1988) J Ceram Trans ACS 2 pp 624-634... 

Benbow JJ, Oxley EW, Bridgwater J (1987) The Extrusion Mechanics of Pastes - the Influence of Paste Eormulation on Extrusion Parameters. J Chem Eng Sci vol. 42 No 9 pp 2151-2162... 

Functionalization of isotactic polypropylene with maleic anhydride by reactive extrusion mechanism of melt grafting. Polymer, Vol. 42, pp. 5549-5557, ISSN 0032-3861. 

PA-6 (50)/PE (40)/EMAA (10 4 mol% acid 38 % Na neutralized) Double-pass extrusion/mechanical properties Mesrobian et al. 1968... 

PA-66 (2.7 parts)/EA-BA-vinyl benzyl chloride copolymer (0.9 parts 0.23-0.33 % reactive chloride) SSE at 280 °C/multiple pass extrusion/ mechanical properties/aiso used vinyl chloroacetate as reactive chloride source Moncur 1982... 

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