Persistence time

Fireballs radiate intense heat, wliich can cause fatal bums and can quickly ignite otlier materials. Tlie diameter and persistence time of the fireballs can be calculated by tlie equations developed by Gayle and Bransford. ... 

W = total mass of combustion reactants including oxygen (lb) tp = persistence time of fueball (s)... 

Fig. 43.—Diagrammatic Plots of Reaction Time, High-intensity Plateau, and Overall Persistence-time at Different Concentrations of Sucrose. ...

Fig. 46.—Schematic Effect of Concentration of Persistence Time (Tp), Subjective Intensity (Si), and Onset Time (Tp) of Sucrose Sweeteners. ...

One of the first considerations in the use of any chemical is possible accumulations of harmful residues in soils. Evidence proves beyond any doubt that many of the newer compounds remain in the soil for at least 5 years. How much longer they may persist, time alone can determine. We know that both selenium and molybdenum can be picked up from soils by plants, which thus become extremely toxic to animals, even when plants themselves are apparently unharmed. Often a given piece of land may be treated safely as far as one crop is concerned but another crop may be injured. For example, potatoes will tolerate large amounts of DDT in the soil as a means of controlling wireworms which are extremely destructive melons, on the other hand, are severely injured by excessive DDT in the soil. There can be no assurance in many cases as to the ultimate use of any... 

Figure 10 (a) Free-volume persistence time extracted from the free-volume autocorrelation function (Eq. [9]) for an attractive colloidal fluid as a function of the strength of the interparticle attraction, (b) Comparison of colloidal self-diffusivity (closed symbols) with that estimated using the free-volume scaling relationship D — A(v )2 /tf discussed in the text (open symbols). Data taken from Ref. 75. 

CASRN 3337-71-1 molecular formula C8H10N2O4S FW 230.24 Soil Asulum is not persistent in soils because its half-life is approximately 6-14 d (Hartley and Kidd, 1987). The short persistence time is affected by soil temperature and moisture content. The half-life of asulam in a heavy clay soil having a moisture content of 34% and maintained at 20 °C was 7 d (Smith and Walker, 1977). In soil, sulfanilamide was reported as a product of hydrolysis. In nonsterile soils, this compound degraded to unidentifiable products (Smith, 1988) which may include substituted anilines (Bartha, 1971). 

In the biodegradation plots and In the Herbicide Storage Areas, high concentrations of herbicides were applied In a short time period and Incorporated Immediately Into the soil profile, and hence, the long persistence time. Nevertheless, these studies do show that the soil chemistry and the soil microbial populations can effectively combine to degrade massive concentrations of the phenoxy herbicides and that recovery of the sites occur as documented by the re-establlshment of the vegetative community. 

The contaminant 2,3,7,8-TCDD has a long persistence time In soils (years) and may be a major consideration In the use of soil biodegradation as a disposal option for "unwanted" phenoxy herbicides or TCDD-contamlnated chemical wastes. 

An aimless path resulting from a set of successive steps (or excursions) whose individual lengths and directions are only randomly related to each other. As with any stochastic process, the preceding step has no influence at all on any of the subsequent steps. See Diffusion Persistence Time Twiddling... 

FLUORESCENCE CHEMISORPTION CHEMOSELECTIVITY Chemotactic bacterial locomotion, TWIDDLING PERSISTENCE TIME "CHEOPS,"... 

PHYSICAL ORGANIC CHEMISTRY NOMENCLATURE PERSISTENCE TIME TWIDDLING PERSISTENT... 

RANDOM WALK DIFFUSION PERSISTENCE TIME TWIDDLING... 

Let us start with a complement to the naive considerations exposed few lines above. An important aspect of the local interactions in condensed media subjected to thermal averaging is their persistence. The persistence is clearly related to the strength of the interaction, but it is also related to the collective effects of the nearby molecules. The persistence times span a wide range from the short times corresponding to librations of... 

The normal incidences are taken to be those of the UNSCEAR column in Table 7-5. The mutation component is taken to be 0.1 for congenital malformations and other multifactorial conditions and 1 for the other categories. The mean persistence times are taken as 4 for dominant and X-linked, 100 for recessives, 1.25 for chromosomal, and 10 for congenital anomalies and multifactorial traits. The normal frequency is 10.5 per 100 live births. The contribution from dominant, X-linked, and cytogenetic disorders is hatched. Because recessive diseases make almost no contribution, the white areas are mainly congenital malformations and other multifactorial conditions. 

As for the effects of the shear stress, it was shown by a Synchrotron radiation X-ray diffraction study that transformations from metastable to more stable forms, especially to Form V, were accelerated by high shear stress (110). Figure 25 shows the time variation of relative intensities of X-ray diffraction peaks of CB crystals formed after cooling from 50°C to 18°C at a rate of 3°C/min. In the case of no shear. Form III appeared at first after the temperature reached at 18°C, and then Form IV crystallized at the expense of Form III. On the other hand, applying the shear stress at 1440 s caused accelerated transformation from Form III to Form V, without the occurrence of Form IV. The same result was observed with lower shear rates (19), and the persistence time of Form III was reduced as the shear rate was increased. Mazaanti et al also observed that the orientation of CB crystals are aligned with the shear flow (110). These results indicated that temperature and shear treatments are the tools for tailoring the desired polymorphic structures of fats. 

The emission lifetime is often used to determine surface temperature with the advantage that the technique is insensitive to blackbody background. This technique requires excitation by a pulsed source, the persistence of the resulting fluorescence can be observed providing that the length of the source pulse is much shorter than the persistence time of the phosphor s fluorescence. For certain phosphors, the prompt fluorescence decay time (t) varies as a function of temperature and is deflned by ... 

CRDEC (Chemical Research and Development Engineering Command). Persistency Times of Chemical Agents on CARC Painted Vehicles and Sand. Aberdeen Proving Ground, MD, 1990. 

Agent is in a frozen state and will not evaporate or decay Agent persistency time exceeds 2,000 hours... 

NOTES 1 For grassy terrain, multiply the number in the chart by 0.4. 2 For grassy terrain, multiply the number in the chart by 1.75. 3 For sandy terrain, multiply the number in the chart by 4.5. Agent persistency time is more than 1.42. Agent is in a frozen state and will not evaporate or decay. Agent persistency time exceeds 2,000 hours. ... 

Spectrum of light with long persistent time shows narrow frequency width. 

In aqueous solution, [RuCl6]2- is rather unstable. Perchlorate solutions containing Rulv, which may be obtained by reducing Ru04 in HCI04 by H202, contain a variety of poorly characterized species,8 probably in part polynuclear and possibly with mixed oxidation states addition of Cl" to such solutions produces a series of color changes whose sequence and persistence times depend upon pH and the Cl" concentration. Polynuclear species, and chloro, aquo and hydroxo species, are doubtless involved. 

The MRT for a drug administered intravenously provides a useful estimate of the persistence time in the body. Therefore, in this sense, it is related to the half-life of a drug. When applied to a drug that distributes rapidly (i.e., one-compartment model), it has been shown that... 

---