Remaining activity

Both molybdate and orthophosphate are excellent passivators in the presence of oxygen. Molybdate can be an effective inhibitor, especially when combined with other chemicals. Orthophosphate is not really an oxidizer per se but becomes one ia the presence of oxygen. If iron is put iato a phosphate solution without oxygen present, the corrosion potential remains active and the corrosion rate is not reduced. However, if oxygen is present, the corrosion potential iacreases ia the noble direction and the corrosion rate decreases significantly. 

A water-soluble white crystalline sofld, CS is disseminated as a spray, as a cloud of dust or powder, or as an aerosol generated thermally from pyrotechnic compositions. The formulation designated CSl is CS mixed with an anti-agglomerant when dusted on the ground, it may remain active for as long as five days. CS2 formulated from CSl and a siUcone water repellent, may persist for as long as 45 days (6). 

The alcohol swells the poly (ethyl methacrylate) beads, rapidly promoting diffusion of the plasticizer into the polymer. As a result of the polymer-chain entanglement, a gel is formed. The conditioner is applied to the denture and provides a cushioning effect alcohol and plasticizer are slowly leached out, and the material becomes rigid. To ensure resiliency, the conditioner must be replaced after a few days. Some materials exhibit high flow over a short period compared with others with low initial flow the latter remain active longer. 

In seawater, HCO3 ions lead to surface films and increased polarization. In aqueous solutions low in salt and with low loading of the anodes, less easily soluble basic zinc chloride [10] and other basic salts of low solubility are formed. In impure waters, phosphates can also be present and can form ZnNH4P04, which is very insoluble [11]. These compounds are only precipitated in a relatively narrow range around pH 7. In weakly acid media due to hydrolysis at the working anode, the solubility increases considerably and the anode remains active, particularly in flowing and salt-rich media. 

In studies of the behaviour of materials that may be either active or passive in the test environment, there would seem to be a real advantage in starting with specimens in an activated state to see if they will become passive, and to ascertain how fast they are corroded if they remain active. If passivity should be achieved after such an activated start, the material can be considered to be more reliable in the test environment than would be the case if by chance it managed to retain an originally induced passivity for all, or most of, the test period. It may also be valuable to know how fast the metal will be corroded by the test medium if activity should persist. 

Henry Gilman (1893-1986) was born in Boston, Massachusetts, and received his Ph D. in 1918 at Harvard. He then became professor of chemistry at Iowa State University 11919-1962), where he remained active until his death at ago 93. An exuemely prolific researcher, Gilman published more than 1000 scientific papers during his career. Remarkably, he lost much of his eyesight at age 53 but still went or to accomplish some of fiis finest work in later years. 

Ligands that bind to the receptor, but do not exert a maximal cellular reaction when applied at saturating concentrations are referred to as partial agonists. Their remaining activity is termed intrinsic activity ranging between 0% and 100%. 

Propafenone is administered orally every 8 hours. Any previously given antiarrhythmic drug should be discontinued before propafenone therapy is started. Dosage changes are done 3 to 4 days apart because of the length of time the drug remains active in the body. 

The spillover effect can be described as the mobility of sorbed species from one phase on which they easily adsorb (donor) to another phase where they do not directly adsorb (acceptor). In this way a seemingly inert material can acquire catalytic activity. In some cases, the acceptor can remain active even after separation from the donor. Also, quite often, as shown by Delmon and coworkers,65 67 simple mechanical mixing of the donor and acceptor phases is sufficient for spillover to occur and influence catalytic kinetics leading to a Remote Control mechanism, a term first introduced by Delmon.65 Spillover may lead, not only to an improvement of catalytic activity and selectivity but also to an increase in lifetime and regenerability of catalysts. 

Do not infer from the above discussion that all the catalyst in a fixed bed ages at the same rate. This is not usually true. Instead, the time-dependent effectiveness factor will vary from point to point in the reactor. The deactivation rate constant kj) will be a function of temperature. It is usually fit to an Arrhenius temperature dependence. For chemical deactivation by chemisorption or coking, deactivation will normally be much higher at the inlet to the bed. In extreme cases, a sharp deactivation front will travel down the bed. Behind the front, the catalyst is deactivated so that there is little or no conversion. At the front, the conversion rises sharply and becomes nearly complete over a short distance. The catalyst ahead of the front does nothing, but remains active, until the front advances to it. When the front reaches the end of the bed, the entire catalyst charge is regenerated or replaced. 

Even if all of the organisms are killed off, their death and breakdown, either by the biocide or by stress rupture, especially if shear mixing is used, may release enzymes. These, unaffected by the biocide, will often be cellulolytic and can remain active for prolonged periods. 

Biocides are formulated into the concentrates of products at anywhere between 20-25 times the end-use concentration. The preservative system must be soluble in the concentrate which may be a mixture of oil and water. The concentrate may then be stored anywhere between three months to one year. During this period of time, the biocide must remain active if it is to be efficacious when the product is used. There are many components in a metalworking fluid formulation that can deactivate certain types of biocides. For example, the presence of primary amines in many products rapidly deactivate isothiazolinone biocides, making this class of biocides unsuitable for use in the vast majority of metalworking fluid concentrates. 

HL is a persistent agent depending on pH and moisture and has been known to remain active for up to 3 years in soil. 

Metals behave differently since the metal atoms are embedded in an electron gas. The attractive forces remain active even after mutual displacement of parts of a crystal has occurred. Metals therefore can be deformed without fracture. 

In 1980, Congress passed the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Commonly known as Superfund, the program under this law is focused on the remediation of abandoned or uncontrolled hazardous waste sites. Since 1980, Superfund has assessed nearly 44,400 sites. To date, 33,100 sites have been removed from the Superfund inventory to aid their economic redevelopment, and 11,300 sites remain active with the site assessment program or are included in the National Priorities List (NPL) for the implementation of remedial actions. By September 2000, 1509 sites were included in the NPL with ongoing or completed cleanup activities. 

All OCPs are polytropic, parenchymatous poisons, afflicting the central nervous system, liver, kidneys, the heart muscle, the stomach and intestines, and the endocrine system (mostly the adrenal glands, thyroid, and ovaries). Morphological changes in warm-blooded creatures poisoned by OCPs vary from insignificant disruptions in circulation and reversible dystrophy to focal necroses these effects depend on the organism, the dose of OCP, how long the OCP remains active, as well as on other factors [9, 39, 40, A47, A79]. 

The relationship between MAP kinase activity and/or its direct substrates (e.g. p90rsk) and CSF inactivation is unclear. Abrieu and colleagues (1996) found that in cell-free Xenopus eggs extracts MAP kinase remains active when MPF is inactivated. Thus, despite the fact that MAP kinase remains continuously active and phosphorylated, the CSF activity seems to be inactivated. A similar pattern... 

The poisoning of the nickel surface is manifested in a sharp increase of electrode potential relative to the value in the active state. Since at most only part of the surface remains active, the actual current density can be much... 

Based upon the activity and electrochemical experimental results the 5%Pt,l%Bi/C catalyst was chosen for further detailed evaluation. For the catalyst to be effective in industrial applications it is desirable that it should remain active for a number of reaction cycles. The recycle capability of 5%Pt,l%Bi/C was evaluated under realistic conditions for a number of selective oxidation reactions, see Table 3. 

A small amount of lingual lipase is also present and plays a role in the breakdown of dietary lipid. This enzyme is optimally active at an acidic pH and therefore remains active through the stomach and into the intestine. 

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