Insufficient Concentration

Many corrosion inhibitors of both the passivating and film-forming types (as explained in the chapter on inhibitor types) are classified as dangerous, because they actually may produce increased localized corrosion and pitting compared to untreated systems if they are used in quantities insufficient to form an effective corrosion-resistant film. For this reason, it is not advisable to attempt reduction of inhibitor costs by reducing dosage below safe, effective levels. 

If iron content is used to measure the results of inhibitor treatment, the initial rise when treatment is begun, usually attributable to cleaning of scaled surfaces, wiU soon fall to a rate less than that before treatment. If it does not, then either too little inhibitor is being used, or the inhibitor is not being added in such a way that it reaches the corroding equipment. 

In actual plant practice, the inhibitor is normally added at concentrations of 5 to 10 times the final desired recommended value. The high concentration reduces the time needed for sloughing of old deposits and also accelerates the attainment of a good film on the cleaned metal. The concentration is gradually reduced after this, until the desired inhibition level (as shown by coupons, resistance probes, water analysis) is attained at an economical cost. 

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The second class of anodic inhibitors contains ions which need oxygen to passivate a metal. Tungstate and molybdate, for example, requke the presence of oxygen to passivate a steel. The concentration of the anodic inhibitor is critical for corrosion protection. Insufficient concentrations can lead to pitting corrosion or an increase in the corrosion rate. The use of anodic inhibitors is more difficult at higher salt concentrations, higher temperatures, lower pH values, and in some cases, at lower oxygen concentrations (37). 

If the light-scattering objects originally present in the airflow are unsuitable for LDA measurements due to insufficient concentration or incorrect estimated flow-tracking capability, the air must be seeded with oil smoke, tobacco smoke, or titanium dioxide tracer particles or droplets. A simple smoke candle is generally suitable for seeding, even if the enclosure is large and the air path is not closed as in several cases of industrial ventilation. 

Microbiocides may be toxic to humans therefore, care must be taken when used. When selecting the microbiocide, the field engineer can obtain pertinent information on chemicals from the service company providing the chemicals. The microbiocide selected must be compatible with the system in which it is being used. Some chemicals such as quaternary amines have dual functions one as microbiocides and the other as film-forming corrosion inhibitors. Insufficient concentrations of this type of chemical may not be enough to coat the whole surface of metal and can cause pitting corrosion. The selection must also depend on chemicals that can produce the desired control in minimum time limits and... 

Safe or dangerous inhibitors Each inhibitor must be present above a certain minimum concentration for it to be effective (see Principles), and this classification relates to the type of corrosion that will occur when the concentration is below the minimum, or critical, value. Thus, when present at insufficient concentration a safe inhibitor will allow only a uniform type of corrosion to proceed at a rate no greater than that obtaining in an uninhibited system, whereas a dangerous inhibitor will lead to enhanced localised attack, e.g. pitting, and so in many cases make the situation worse than in the absence of an inhibitor. 

That the same enzyme,28 sucrose phosphorylase, is involved in the reaction of L-arabinose is indicated by the following observation. When L-arabinose is added to a mixture containing the enzyme, D-glucose-1-phosphate and D-fructose, of which the last is present in insufficient concentration to give the maximum rate of sucrose formation, an increase... 

Although sodium adducts were preferably formed in both instruments, even in the absence of added electrolyte, in order to avoid the possible reduction in ionisation due to insufficient concentration of metal ions in solution, it is recommended that sample extracts are fortified with sodium ions prior to injection. However, the addition of higher concentrations can induce system instability and analyte suppression. Therefore, the concentration of added electrolyte should... 

The application of electron diffraction may be hindered, however, by the lack of knowledge of the vapor composition or by the insufficient concentration of the species to be investigated. The solution to this problem is the simultaneous mass ectrometric and electron diffraction measurements. In this combined experiment the vapor composition and the optimal experimental conditions are determined prior to and during the diffraction experiment. We have employed this combined technique in the Budapest laboratory and are aware of similar attempts at the University of Oslo and The University of Texas at Austin. 

The kinetic curves in Figure 4.4 show that the cyclopentene consumption rate decreases insignificantly after reaching its maximal yield. This testifies to an insufficient concentration of H202 at the stage of cyclopentadiene formation. The kinetic curves of cyclopentadiene accumulation are S-shaped, which indicates autocatalytic type of the process with an autoacceleration period from the beginning of these curves to inflection points. 

Concentrations of metal ions in the burial environment can lead to localized conditions of toxicity, which can prevent microbial activity (Janaway 1996). This phenomenon is typically associated with the preservation of associated grave materials such as textiles, leather, and wood (ibid.). However, an extensive collection of metallic artefacts usually contains insufficient concentrations of metal ions to result in significant retardation of decomposition (ibid.). 

The patient s pupils should be maximally dilated. Poor pupillary dilation, media opacities (cornea, lens, or vitreous), poor patient cooperation, and an insufficient concentration of fluorescein all contribute to suboptimal results. Improper injection technique most often contributes to decreased retinal-choroidal fluorescein concentration. A crash cart (cardiopulmonary resuscitation unit) must be on hand to handle any potential side effects. 

Some malignant cells appear to have insufficient concentrations of 5,10-methylene tetrahy-drofolate, and thus cannot form maximal levels of the inhibited TS-FdUMP-folate ternary complex. Addition of exogenous folate in the form of leucovorin increases formation of the complex and has enhanced responses to 5-FU. 

Zinc is an essential element for the growth of plants. An insufficient concentration in plant tissues is shown by growth disturbances. Its toxic effect is manifested only very rarely, in areas with a high soil pollution by this element. The zinc concentration in grasses and cereals is typically between 10 and 100 mg kg . ... 

Chemiluminescence and photoluminescence in diatomic iron oxide, Rb2, and alkali-metal dimers with halogen atoms and metal vapour-oxidant flames,202 203 lifetime measurements of selectively excited states of diatomic hydrides,204 photodissociation of alkali-metal halide vapours,206 spin-orbit relaxation of the HTe ( 2IIi) radical,20 the photodecomposition of metal carbonyl anions such as [Mn(C04)] in the vapour phase,207 and the fluorescence of Rhodamine 6G in the vapour phase 208 have been studied in recent reports. In the last study it was concluded that an insufficient concentration of the fluorescing dye could be maintained in the vapour phase to permit laser action to occur. 

Migrating antistats are time-sensitive in their use. Time is required for the additive to migrate to the surface of the PO produrt and to attract moisture from the air and minimize static buildup. This migration may delay its reaching optimum antistatic effectiveness by days or weeks, especially with a crystalline polymer like PP. Other factors affect the migration rate, such as the presence of other additives, insufficient concentration of the antistat, and temperature. 

In contrast to layer corrosion in aluminum alloys, line type corrosion can occur in many materials, although it is also linked to forged and rolled products. The cause of line type corrosion may be due to both the banded structure of precipitations and microsegregation (i.e., insufficient concentration compensation). 

At the ED q for T4 (0.2 ug/100 g BW) for Type II enzyme suppression there was only 3.4 pg rT3/g cerebral cortex, an insufficient concentration to affect deiodinase activities. With a three times larger T4 dose, rT3 levels rose to 18 pg/g, sufficient to cause about 20% inhibition of deiodinase activity. The deiodinase suppression was 70% at this T4 concentration. This is an especially relevant T4 dose since the serum T4 concentration four hours after this dose is 35 ng/ml, a normal value for euthyroid rats. These results allowed the conclusion that virtually all of the Type II deiodinase suppressive effect of T4 in the euthyroid cerebral cortex derives from T4 per se with a maximum of 20% owing to the rT3 locally derived from it. Thus, we are unable to assign a significant physiological role for the rT3 in the cerebral cortex as a regulator of 5 deiodinase activity. 

There appears to be a shallow approach to the maximum efficiency zone on the hydrophilic side of a homologous series (high CAC) and an abrupt drop where efficiency is suddenly lost on the hydrophobic side, at approximately 2 x 10" M. This sudden loss is believed to be due to an insufficient concentration of monomer within an average diffusion distance from the surface to form a monolayer capable of lowering surface tension (for the 0.1 s time scale). 

Compromised penetration of cytotoxic Insufficient concentrations of drugs and... 

Migration current is observed in addition to the diffusion current in solutions with insufficient concentration of supporting electrolyte. This current is due to the migration of ions in the electric field between the two electrodes. Under normal conditions, in which the molar concentration of the supporting electrolyte is more than twenty times higher than that of the substance studied, this current is negligible. 

Emulsion build up by recycling and pumping insufficiently concentrated surface oil too often. 

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