Refractory linings notes

Figure 14-6. Schematic diagram of the effects of class III agents. All class III drugs prolong the AP duration in susceptible cardiac cells by reducing the outward phase 3 potassium current (1, wavy lines). The main effect is to prolong the effective refractory period. Note that the phase 4 diastolic potassiuni current (1,, ) is not affected by these drugs.

The roasted clinker is then leached out with hot water and the resulting liquor filtered to remove insoluble silica, along with aluminum and iron oxides present as impurities in the original chromite ore. Pure sodium dichromate is then crystallized and dried. The anhydrous sodium chromate can then be reduced to chromium trioxide by simple carbothermic reduction. Note that the sodium chromate produced can be converted into the dichromate by dissolving it in sulfuric acid and is the basis for the manufacture of all industrially important chromium chemicals. Once produced, chromium trioxide is mixed with aluminum powder and lime and placed inside a refractory-lined steel vessel. The exothermic reaction is started by igniting a pyrotechnic mixture made of barium peroxide and aluminum powder or potassium chlorate aluminum powder ... 

Initially, when unshaped refractories were first used, the property requirement was kept the same as for shaped refractories, in thatthey mainly replaced linings. Later on, when the use of these refractories became widespread, new standards had to be developed. The first standards on unshaped refractories by the American Society for Testing of Metals (ASTM) were published in 1943 [3]. They were numbered as C 179 and C 181 C 179 covered "drying and firing linear change of plastics and rammings" and C 181 dealt with "workability index of plastic refractories." As noted earlier. World War II saw an increase of about 35% in unshaped refractory production. Specifications were required to obtain the required items from many manufacturers. 

Unfortunately, there is no way to predict the actual quality outcome of thousands of mortar joints in a typical refractory application, so some designers believe that joints should be minimized or mortar eliminated in favor of precision-machined contact. However, it should also be noted that properly prepared and applied mortar joints provide critical dififerential expansion compensation and actually enable mortared carbonaceous refractory linings to accommodate high differential stresses and avoid cracking. Machined contact joints provide... 

Amphotericin B Cholesteryl (Amphotec) [Antifungal/Polyene Mocrollde] Uses AspCTgillosis if intolCTant/refractory to conventional amphotericin B, systemic candidiasis Action Binds ceU membrane sterols, alters permeability Dose Adults Peds. Test dose 1.6—8.3 mg, over 15-20 min, then 3-4 mg/kg/d 1 mg/kg/h inf w/ renal insuff Caution [B, ] Disp Inj SE Anaphylaxis fever, chills, HA, nephrotox, -1- BP, anemia Notes Do not use in-line filter Interactions See Amphotericin B EMS See AmphotCTicin B OD May cause cardiac arrest s ptomatic and supportive... 

Recently, intravitreal triamcinolone acetonide has been used clinically to treat retinal vascular disease (Fig. 4). A case report by Jonas and Sofker (32) described a patient with nonproliferative diabetic retinopathy and a six-month history of persistent, diffuse macular edema despite grid photocoagulation. Following one intravitreal injection of triamcinolone acetonide, the visual acuity of this patient improved from 20/200 to 20/50 over a five-month follow-up period. It was also noted that there was marked regression of macular edema on clinical examination. Martidis et al. (33,34) reported on the use of intravitreal triamcinolone for refractory diabetic macular edema. Sixteen eyes with a macular thickness of at least 300 pm despite prior photocoagulation were treated with 4 mg injections of triamcinolone. At three-month follow-up the mean decrease in central retinal thickness was 57.5%, with a visual acuity increase of 2.4 Snellen lines. Those with six-month follow-up demonstrated some recurrence of edema and visual acuity improvement was reduced to 1.3 lines. 

Figure 14-5. Schematic diagram of the effects of class I agents. Note that all class I drugs reduce both phase 0 and phase 4 sodium currents in susceptible cells (shown as wavy lines). Class lA drugs also reduce potassium current (1, ) and prolong the AP duration This results in significant prolongation of the effective refractory period. Class IB and class 1C drugs have different (or no) effects on potassium current and thus shorten or have no effect on the action potential duration.

Figure 14-7. Schematic diagram of the effects of ciass iV drugs in a calcium-dependent cardiac cell in the AV node (note that the AP upstroke is due mainly to calcium current). Class IV drugs reduce inward calcium current during the action potential and during phase 4 (wavy lines). As a result, conduction velocity is slowed in the AV node and refractoriness is prolonged. Pacemaker depolarization during phase 4 is slowed as well if caused by excessive calcium current.

British Ceramic Research Assoc., Thermomechanical Behavior of Refractory Castable Linings, Technical Note No. 320, March 1981. 

Fig. 12.1.13. Roof, barrel and vortex tube sections of an FCCU cyclone lined with ACTCHEM high temperature erosion protective refractory over Hexmetal. Note inlet scroll starting in lower right-hand comer of image. Courtesy of Actchem, Inc.

Figure 8 shows the temperature contour lines for the steady-state thermal analysis. Note the brick half-section was modeled with an element mesh of 9 elements across the width and 18 elements along the length. The element mesh chosen is typically based on the expected nonlinear stress-strain behavior of the refractory and the nonlinear compression-only behavior of the brick joint. In the case of castable systems, the circumferential width of the model is selected by trial solutions to determine the estimated maximum circumferential tensile stress that could be developed by the castable lining. Figure 8 is a line contour plot in which the letters on the contours represent a temperature at that location. Color contour plots are also available from most programs and provide a much better visualization of the temperature distribution, especially for more complicated temperature distributions. 

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