Effect of metastability

Radiative lifetime of triplets. Biochemical effects Neutralization time for media at very high viscosity. Time for mitosis. Biochemical effects of metastables. DNA synthesis time Biological effects Late biological effects... 

In contrast to the solubility enhancing effect of metastable solids, there are some potential disadvantages that must be taken into account. In most cases, suspensions of metastable solids are n feasible owing to rapid transformation of the excess solid to the stable (low solubility) form. Shefter and Higuchi (1963) showed that many nonsolvated forms transform to the hydrated form in aqueous... 

Solubility estimates made by the techniques discussed above are reported in the last column of Table H. In addition to the limited number of such measurements, the results do not compare favorably in all cases with the theoretical values listed. This fact is hardly surprising considering the recognized limitations in the thermodynamic data base and difficulties encountered in interpreting results of solubility experiments. Furthermore, the theoretical estimates are based on the assumption that the thermodynamically most stable solid for a radionuclide controls its solubility. The effects of metastability are not included and, in this sense, theoretical solubility estimates are not conservative. A series of sorption-type experiments designed to yield solubility estimates for a number of the radionuclides included in this paper is in progress, and the results will be reported at a later date. 

Radiative Processes.—A large number of papers concerned with the various aspects of the electronic absorption and emission processes in atomic species have appeared. Of general interest is a paper which presents an expression suitable for the evaluation of the infinite sum describing absorption due to a hydrogenic series of Lorenzian lines.444 The Doppler lineshape in atomic transitions,448 collision effects on lineshapes of atomic transitions,44 the effect of metastable dimers on the radiative transition in pairs of atoms 447 and in donor-acceptor pairs,448 and other aspects of excitation transfer in two-atom systems,449- 480... 

Hu W, Cai T (2008) Regime transitions of polymer crystal growth rates molecular simulations and interpretation beyond Lauritzen-Hoffman model. Macromolecules 41(6) 2049-2061 Hu W, Frenkel D (2004) Effect of metastable liquid-liquid demixing on the morphology of nucleated polymer crystals. Macromolecules 37(12) 4336-4338 Hu W, Frenkel D (2005) Polymer crystallization driven by anisotropic interactions. Adv Polym Sci 191 1-35... 

Hu W, Frenkel D. Effect of metastable liquid-liquid demixing on the morphology of nucleated polymer crystals. Macromolecules 2004 37 4336 338. 

Cheng SZD, Zhu L, Li CY, Honigfort PS, Keller A. Size effect of metastable states on semicrystalline polymer structures and morphologies. Thermochim Acta 1999 332 105-13. 

Figure A2.5.7. Constant temperature isothenns of reduced Helmlioltz free energy A versus reduced volume V. The two-phase region is defined by the line simultaneously tangent to two points on the curve. The dashed parts of the smooth curve are metastable one-phase extensions while the dotted curves are unstable regions. (The isothenns are calculated for an unphysical r = 0.1, the only effect of which is to separate the isothenns...

Fig. 11. Effects of pH in the colloidal siUca-water system (1), where A represents the point of zero charge regions B, C, and D correspond to metastable gels, rapid aggregation, and particle growth, respectively. Positive and negative correspond to the charges on the surface of the siUca particle.

The a — 0 transformation has a large hysteresis in hydrogenated titanium alloys, and different thermal treatments change their phase content. Various degrees of metastability due to hysteresis are implicit for the alloys after different thermal treatments. Metastable phases undergo transformation to a more equilibrium state during deformation, which can effect the flow of the alloy. Below we consider the effect of the thermal pre-strain treatment on ductility on the strength of the Ti-6A1-2Zr-1.5V-lMo-rH alloys. ... 

Needless to say, tunneling is one of the most famous quantum mechanical effects. Theory of multidimensional tunneling, however, has not yet been completed. As is well known, in chemical dynamics there are the following three kinds of problems (1) energy splitting due to tunneling in symmetric double-well potential, (2) predissociation of metastable state through... 

The nuclear decay of radioactive atoms embedded in a host is known to lead to various chemical and physical after effects such as redox processes, bond rupture, and the formation of metastable states [46], A very successful way of investigating such after effects in solid material exploits the Mossbauer effect and has been termed Mossbauer Emission Spectroscopy (MES) or Mossbauer source experiments [47, 48]. For instance, the electron capture (EC) decay of Co to Fe, denoted Co(EC) Fe, in cobalt- or iron-containing compormds has been widely explored. In such MES experiments, the compormd tmder study is usually labeled with Co and then used as the Mossbauer source versus a single-line absorber material such as K4[Fe(CN)6]. The recorded spectrum yields information on the chemical state of the nucleogenic Fe at ca. 10 s, which is approximately the lifetime of the 14.4 keV metastable nuclear state of Fe after nuclear decay. 

If the work function is smaller than the ionization potential of metastable state (see. Fig. 5.18b), then the process of resonance ionization becomes impossible and the major way of de-excitation is a direct Auger-deactivation process similar to the Penning Effect ionization a valence electron of metal moves to an unoccupied orbital of the atom ground state, and the excited electron from a higher orbital of the atom is ejected into the gaseous phase. The energy spectrum of secondary electrons is characterized by a marked maximum corresponding to the... 

Making the flow rate higher or lower will change from stable to metastable the folded or the stretched state, respectively. The effects of hysteresis associated with this first-order discontinuous transition play an important role in the formation of composite crystalline structures. 

Palladium acetate, [PdO —02CCH3)2l3, possesses a unique quality that makes it attractive for solid state decomposition studies as well as technological applications. It can be spin-coated from solution to form a homogeneous, apparently amorphous solid film. This provides large uniform areas over which we can study the effects of various irradiation sources on the chemical nature of the film. The bulky structure of palladium acetate, shown in Figure 1 (8), may offer a partial explanation of the molecule s ability to achieve an amorphous metastable phase upon rapid evaporation of solvent. 

Since it was known that theophylline monohydrate can be thermally dehydrated to form either the stable Form I or the metastable Form I, the effect of different drying methods on the phase composition was studied [89], Using either a multichamber microscale fluid bed dryer or the hot stage of a variable-temperature XRPD diffractometer, Form I was produced when the drying was conducted at 40-50°C. Drying at 60°C in the VT-XRPD unit yielded only Form I, while mixtures of products were produced in the microscale fluid bed dryer even at temperatures as high as 90 °C. 

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