Expected volatility measurement

The reason for the observed dechne in measured mercury concentration in successive measurements is thought to lie in the fact that volatile (elemental) mercury in the headspace (25 ml) of the sample bottle is lost when the bottle is opened. When the bottle is closed, volatile mercury in the liquid phase redistributes to the headspace of the bottle, and thus the first aliquot reflects a higher concentration (in the liquid phase) than aliquots obtained in successive removals. If volatile mercury is lost when bottles are opened, one would expect the measured concentration in liquid aliquots to diminish the more times a bottle was opened until most of the volatile mercury had escaped and only non-volatile mercury forms remained. The data suggest that only a relatively small number of bottle openings is sufficient to deplete a significant portion of the volatile mercury in the sample bottle. 

Tracking error, a common measure of portfolio risk, measures the expected volatility (in basis points of total return) of the portfolio against its benchmark over a specified period. 

The price risk can be defined and understood in alternative ways. One can view the risk as the probable fluctuation of the price around its expected level (i.c., the mean). The larger the deviation around the mean the larger is the perceived price risk. The volatility around the mean can be measured by standard deviation and be used as a quantitative measure for price risk. At the same time, in the industry it is common to define risk referring only to a price movement that would have an adverse effect on the profitability. Thus, one would talk about an upward potential and downside risk. ... 

Hexachloroethane released to water or soil may volatilize into air or adsorb onto soil and sediments. Volatilization appears to be the major removal mechanism for hexachloroethane in surface waters (Howard 1989). The volatilization rate from aquatic systems depends on specific conditions, including adsorption to sediments, temperature, agitation, and air flow rate. Volatilization is expected to be rapid from turbulent shallow water, with a half-life of about 70 hours in a 2 m deep water body (Spanggord et al. 1985). A volatilization half-life of 15 hours for hexachloroethane in a model river 1 m deep, flowing 1 m/sec with a wind speed of 3 m/sec was calculated (Howard 1989). Measured half-lives of 40.7 and 45 minutes for hexachloroethane volatilization from dilute solutions at 25 C in a beaker 6.5 cm deep, stirred at 200 rpm, were reported (Dilling 1977 Dilling et al. 1975). Removal of 90% of the hexachloroethane required more than 120 minutes (Dilling et al. 1975). The relationship of these laboratory data to volatilization rates from natural waters is not clear (Callahan et al. 1979). 

Samples that have low vapor pressure or extracts that are expected to contain components of low volatility can be analyzed by HPLC. The liquid sample is introduced via an injection valve and components separated by a chromatographic column. As components exit the column, they enter the MS where some of the eluent is stripped away and the remaining liquid enters the mass spectrometer. As with GC-MS, the mass spectrometer does not measure... 

This research demonstrates the utility of a well-defined set of polymers with carefully controlled structure for relating structure to radiation resistance. The presence of the isopropylidene group in the polymer apparently had little effect on the radiation resistance of the polymer, as determined from volatile product yields, contrary to initial expectations. G(CH ) was extremely small, indicating that isopropylidene bond scission is of a low probability. This was further confirmed from G(SO ) measurements. 

Recent publications lead to the conclusion that ammonia contributes to the effects of acid precipitation. The main source of ammonia is animal production and regions with a high animal density are expected to have a high emission of ammonia. Because it is a volatile compound research workers in the field of odour measurement and odour control have the best knowledge and the best tools to study ammonia emissions. A proposal is made for the main goals of a research program. 

Ruhr et al. 1948), and is also expected on the basis of the relatively small K°c (measured values range from 1 to 10) for this chemical (ERA 1986b Roy and Griffin 1985). Volatilization of bromomethane from soil is also relatively rapid, with half- lives ranging from 0.2 to 0.5 days, depending on depth (Jury et al. 1984). 

The dominant fate process for chloroform in surface waters is volatilization. Chloroform present in surface water is expected to volatilize rapidly to the atmosphere. An experimental half-disappearance range of 18-25 minutes has been measured for volatilization of chloroform from a 1 ppm solution with a depth of 6.5 cm that was stirred with a shallow pitch propeller at 200 rpm at 25 °C under still air ( 0.2 mph air currents) (Dilling 1977 Dilling et al. 1975). Using the Henry s law constant, a half-life of 3.5 hours was calculated for volatilization from a model river 1 meter deep flowing at 1 meter/second, with a wind velocity of 3 m/second, and neglecting adsorption to sediment (Lyman et al. 1982). A half-life of 44 hours was estimated for volatilization from a model pond using EXAMS (1988). 

Generally, one would expect that the most volatile component would evaporate first, and this would probably be the diluent. In several cases of operating simulated solvent extraction processes at temperatures up to 70°C, it has been noted that the diluent is rapidly volatilized [G. M. Ritcey and B. H. Lucas, unpublished data]. Problems of volatilization appear not to have occurred to any great extent in the past (perhaps the losses were not measured), but any trend to the use of elevated temperatures would require that this form of solvent loss be thoroughly investigated. 

Trace element measurements in lunar basalts also indicate that the Moon is depleted in highly volatile elements (Taylor et al., 2006a). Estimates of some of the Moon s volatile element concentrations are compared with the Earth in Figure 13.11 a. The absence of water in lunar basalts suggests that the mantle is dry. The Moon may also be enriched in refractory elements (Fig. 13.11b). Volatile element depletion and refractory element enrichment are expected consequences of the giant impact origin and subsequent high-temperature accretion of the Moon. 

Diazinon released to water from both point and nonpoint sources may be emitted to the atmosphere by volatilization, sorbed to soils and sediments, or accumulated in aquatic organisms. While evaporation may not be expected to be significant based upon the Henry s law constant (see Table 3-2), volatilization of diazinon can be an important transport process. Sanders and Seiber (1983) reported that 17% of the diazinon added to a model pond volatilized in 24 hours. Diazinon released to water also may be adsorbed moderately by soils and sediments based on its organic carbon partition coefficient (K00) values measured in soil (Sharom et al. 1980a). Because this pesticide is only moderately adsorbed by some soils, leaching into groundwater can occur. 

Results The data in Table II offer the opportunity to compare phthalates of four different eight-carbon alcohols. The performance differences are perhaps greater than would be expected from such simple variations in skeletal makeup. The most notable differences are in volatility and low temperature properties, but other minor differences also exist. Greater linearity leads to increased efficiency (as measured by the 100% modulus), lower volatility, better flexibility at low temperatures, and better resistance to soapy water. In most circumstances, the linear alcohol phthalates are quite similar to straight chain phthalates. This is to be expected in view of the close similarity of structures. (The true value of a plasticizer system must, of course, consider not only oerformance but price. Thus, high efficiency can sometimes be a disadvantage when costs on a pound volume basis are calculated. In other words, a less efficient plasticizer often gives the lowest compound pound volume cost.)... 

M[N(SiMe3)2 ] 3, M = Sc, Ti, Cr, and Fe, are stable, relatively volatile compounds that proved suitable for UPS measurements (200). With the exception of Sc[N(SiMe3)2 ] 3, which possesses a pyramidal (C3) structure (143), these compounds are expected to adopt Z)3 MN3 skeletal geometries. The dihedral angle 0 between the NSi2 and MN3 planes is not generally known for all the compounds however, 0 is 49° for Fe[N(SiMe3)2 ] 3 (41). Crystal field calculations... 

Both samples are in the form of pellets containing antioxidants as specified on the certificates. They have also been examined for sample homogeneity by dilute-solution viscosity. In the case of the linear material, SRM 1475, although the lot is uniform with respect to location, a measurable pellet-to-pellet variation exists. To make certain that a uniform sample is obtained, at least one gram of pellets should be blended to reduce the expectation of error from pellet variability to less than 0.5%. The branched material on the other hand is quite uniform and does not show pellet-to-pellet variation. Both materials have low ash and volatile content. 

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