Half-value period

Thus, extension of the blood circulation time of the micelles as well as a regulated release rate of the CDDP from the micelle was concluded to be necessary to achieve a more effective anti-tumor activity. This was eventually achieved using PEG-PGlu instead of PEG-PAsp. Here, CDDP was loaded in the micelle in a similar manner to the PEG-PAsp metal complexation with the ligand substitution reaction between CDDP and the carboxylic group of PEG-PGlu (Fig. 3b) [60]. The formed micelle had a very narrow size distribution with an approximately 30 nm diameter. The PEG-PGlu(CDDP) micelle showed a more sustained release of CDDP (half-value period > 90 h) than... 

Fig. 13.—The radioactive transformation scries. The changes indicated by vertical lines correspond to a-emission, by horizontal lines to /d-emission in the former the atomic weight falls by 4, the atomic number by 2 in the latter the atomic weight remains approximately constant, and the atomic number increases by i. Shaded circles indicate a-rays circles without shading, -rays. The size of each circle corresponds to the half-value period.

The half-value period of the radio-phosphorus was found to be... 

Table 1 Rates, rate constants and half-value periods for photocatalytic degradation of RO 84...

The part of the radioactive series b ioning at radium is own bdow with the nature of the particles emitted and the half-value periods (Mattauch, Nuclear physical tables", Intersdence, 1946). 

We note that all the half-value periods of radium A, B, C, C are neg ble compared with that of radon consequently radioactive equilibrium between these and radon may be assumed. 

We examined in our experiments the factors that influence electrokinetic cleaning of different clay grounds (from sandy loam to clay) from radioactive nuclides containing isotopes of °Sr, Sr, Cs, Cs, and so on. Of them, isotopes of °Sr and Cs are the most biologically harmful, having half-value periods of 28 and 30 years, respectively. These and other radioactive isotopes are present in both free (dissolved) and sorbed forms on particle surfaces (Cornell, 1993). 

Berkeley cyclotron for several months prior to shipping the plate to Segre s group in Italy in late December, 1936. Perrier and Segre began their radiochemical studies in late January, more than 6 weeks after the end of bombardment. On the surface exposed to the deuterons, they found strong activity, chiefly due to very slow electrons ascribed to more than one substance of a half-value period of some months in addition to (which they could not explain, but did not attribute to reactions with molybdenum). 

Halb-weiss, n. Textiles) half-bleach, -wert-druck, m. half-value pressure, -wertsbreite, /. width at half of maximum intensity (of a spectral line or band), -wertzeit,/. half-life period. -woUe, /. half-wool, union. -woU-farberei, /. union dyeing, -wuste, /, semi-desert. 

Substituting the values for the example, noting that the maximum outlet concentration will occur at the end of the half-hour period of high inlet concentration. 

The reaction rates can also be expressed in terms of half-life or half-life period. The half-life period is defined as the time required for the concentration of a reactant to decrease to half of its initial value. 

Half-life period gives the time T which must elapse for the radioactivity to decay to half its value at any instant and may be obtained by pulling... 

The reactions were done in the thermostated cell compartment of a Shimadzu QV-50 spectrophotometer. The wavelength was fixed at 300 nm. The sample and reference cells contained a solution of alcohol and dibutyltin dilaurate in dry DMF and were thermostated before use in the cell compartment. At zero time, a small quantity of solid MDI was rapidly dissolved in the sample cell and the absorbance recorded as a function of time. The end value of the absorbance (Aw) was determined after eight to 10 half-life periods. 

Linek and Mayrhoferova (L16) have used electric conductivity to measure the dispersion height, based on locating the surface elevation at certain selected points by means of an electrically conductive probe. The height is determined by the vertical position of the probe tip for which the integrated time of contact is exactly half the period of measurement. The accuracy of the measured value of the total surface elevation is claimed by... 

Nucleation is assumed to occur when P = 0.5. Then, the half-life period r (median value of duration) required to get at least one vapour nucleus is ... 

The central region, corresponding to the area of dry contact, is dark because of the phase change of half a period due to reflection at the ball surface. The first dark ring corresponds to a film thickness t = X/2n. By measuring the radial coordinates of the rings for a succession of values for o, a topographical map of the ball surface can be constructed. 

In this study, the concentration data of Pb, Mn, Cr, and Cd collected in 13 cities over a 16-year period (1991-2006) were analyzed to characterize the environmental behavior of airborne metals under diverse held settings. As a simple means to examine the long-term variability of metal distributions, all data were analyzed after being grouped into the hrst half (period I 1991-1998) and the second half term (period II 1999-2004). These data were also analyzed across the entire study period to account for their long-term trend. Finally, the spatial variability of different metals was also assessed by comparison of their mean values among different cities. 

In the first case, oxidation-reduction potential is determined from relative component concentrations of a single redox-couple. Usually such couples are selected among transitional metals, most often Mn / Mn, Fe VFe, Sff /Sn, Cu VCu, etc. These metals are not always potential-setting but redox reactions between them are considered the fastest, sometimes with the half-life period measured in minutes or hours. Besides, their cations are more rare in the composition of more complex compoxmds, and their concentrations are less dependent on pH values. The method of evaluating Eh from a redox-couple Fe VFe is shown in the example 2.2. 

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