Related Problems

Hypotension is common during hemodialysis. When it occurs early (within the first half hour), it may be due to overmedication with antihypertensive agents, pericardial effusion, or the first-use syndrome. Later in dialysis hypotension usually results from excessive ultrafiltration, abnormal left ventricular fiinction, or the peripheral vasodilatory effect of acetate in the dialysis bath. Prevention depends on the cause of hypotension. It includes the administration of saline intravenously, controlling the rate of ultrafiltration, increasing the dialysate sodium concentration to about 140 mEq/liter, or substituting bicarbonate for acetate in the dialysis bath (B22). 

This syndrome may occur occasionally with the first use of a dialyzer, usually of the cuprophane type, and is an anaphylactic reaction with hypotension, wheezing, and flushing. Rarely it may be severe, resulting in death from marked bronchospasm and shock. In most cases the symptoms subside upon stopping the dialysis without returning the blood in the extracorporeal circuit to the patient, but a few patients require vigorous treatment for anaphylactic shock. 

There may be more than one cause for this syndrome. Complement activation by bioincompatible membranes (H4) hypersensitivity to the ethylene oxide used in dialyzer sterilization, to phthalic anhydride, or to isocyanates (plasticizers) used in potting compounds present in the dialyzer caps and entry of bacterial endotoxin from the dialysate into the bloodstream may each play a role (B22, H4, 12). Hypoxemia and high serum levels of the C3a and C5a complement fragments would suggest complement activation (C2, H4), and peripheral blood eosinophilia and high plasma IgE levels would point to a hypersensitivity reactions. Fever and chills, on the other hand, would incriminate endotoxemia. 

The first-use reaction does not usually occur with subsequent uses of the dialyzer, and may be prevented by thorough rinsing of new dialyzers. It is less common with more biocompatible membranes e.g., cellulose acetate, polyacrylonitrile, or polymethacrylate (B22, H4, 12). 

Muscle cramps occur in about 20% of hemodialysis patients. They may be excruciating but are of no serious consequence. They occur mainly in the legs, but may involve the muscles of the abdomen, chest wall, and upper extremities. Cramps occur late in dialysis, may last several minutes, and are usually related to 

See Chap. 3, Tuberculation Chap. 7, Acid Corrosion and Chap. 16, Galvanic Corrosion.  

Stainless steel corrugated plates from a plate-and-frame heat exchanger. Closed chill water cooling loop used to cool continuous caster mold. 

Cooling water side Softened cooling water with chromate treatment 

Mold side Mold cooling water after cooling molten steel Less than 1 year 

cracklike pits run transversely across the apex of many corrugations on the stainless sheets (Figs. 2.24 and 2.25). The corrosion sites originate at the apex of the corrugations at small circular discolorations, spaced apart exactly the peak-to-peak distance between corrugations. All cracklike pits are aligned in the same direction, regardless of their locations on the plate. 

The wave field produced in the steady, two-dimensional flow of a reacting gas past a wavy wall has been treated in [63] and [64]. Lick [65] has obtained solutions to the nonlinear, steady, two-dimensional conservation equations governing the flow of a reacting gas mixture about a blunt body. Reviews of these and other studies may be found in [1], [2], and [66]-[71]. 

FIGURE 4.8. Schematic diagram of a steady, two-dimensional sound wave in a supersonic reacting gas stream. 

Clarke and M. McChesney, The Dynamics of Real Gases, London Butter-worths, 1964. 

Vincenti and C. H. Kruger, Jr., Introduction to Physical Gas Dynamics, New York Wiley, 1965. 

Thermal Regimes of Combustion, New York McGraw-Hill, 1961, Chapter 2. 

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A related problem concerns the synthesis of p nitrobenzoic acid Here two meta directing substituents are para to each other This compound has been prepared from toluene according to the procedure shown... 

Another fire-related problem that has seen some research effort is that of smolder resistance of upholstery and bedding fabrics. Finishing techniques have been developed to make cotton smolder-resistant (152—156), but the use of synthetic barrier fabrics appears to provide a degree of protection. Work also has provided a means of producing cotton fabrics that have both smooth-dry and flame-retardant performance (150,151). In this case, the appHcation of FR treatment should be performed first, and DP treatment should be modified to accommodate the presence of the FR polymer on the fabric. 

With the increasing emphasis on energy conservation and environmental considerations, additives for fuels that can correct combustion-related problems have aroused considerable interest. Many commercial fuel additives are combinations of organometaHics, dispersants, emulsifiers, and carrier solvents. The organometaHic, often a metal soap, acts as a combustion catalyst, increasing efficiency with reduction of smoke, deposits, and corrosion. 

A related problem is the allocation of costs when a raw material for one process operation is produced internally by another process operation of the same organization (17). The transfer or captive price assigned to the raw material can range from the production cost to a market price that reflects a total profit margin for the material producer, depending on the accounting procedures adopted. 

As the mechanical integrity of the pump system changes, the amplitude of vibration levels change. In some cases, in order to identify the source of vibration, pump speed may have to be varied, as these problems are frequency- or resonance-dependent. Pump impeller imbalance and cavitation are related to this category. Table 10-11 classifies different types of pump-related problems, their possible causes and corrective actions. 

Typical pump-related problems are classified under... 

Microbiauy induced corrosion (MIC) probes. Devices are available to measure the amount of microbial activity in some environments. MicrobiaUy induced corrosion is known to be an actor in many corrosion-related problems in processing plants. The monitoring devices for MIC are limited in their range and, at present, are available only for a few specific environments. This is an exciting area for development of corrosion probes and monitoring systems. 

The three major forms of concentration cell corrosion are crevice corrosion, tuberculation, and underdeposit attack. Each form of corrosion is common in cooling systems. Many corrosion-related problems in the cooling water environment are caused by these three forms of wastage. The next three chapters—Chap. 2, Crevice Corrosion, Chap. 3, Tuberculation, and Chap. 4, Underdeposit Corrosion — will discuss cooling water system corrosion problems. 

General Description Locations Critical Factors Identification Elimination Cautions Related Problems Case Histories... 

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