Physico transformation

Knowledge of the mechanism of action and investigations on the physico-chemical characteristics of the therapeutically used dalbaheptides has stimulated the transformation of natural antibiotics into new derivatives using both chemical and biosynthetic modification. 

On a global scale, the atmosphere serves as the major pathway for the transport and deposition of contaminants from emission sources to terrestrial and aquatic ecosystem receptors (22, 27). Once a contaminant is airborne, the processes of atmospheric di sion, transport, transformation, and deposition act to determine its fate. These processes are complex and the degree to which they influence the fate of a particular contaminant is dependent on its physico-chemical characteristics, the properties and concentrations of coexisting substances, and the prevailing meteorological conditions, including wind, precipitation, humidity, temperature, clouds, fog, and solar irradiation. 

Transformation of parent contaminants into secondary products may occur during the processes of atmospheric diffusion and transport as a result of physical, chemicjd, and photochemical processes (22). Chemical conversion within the atmosphere may also change the physico-chemical characteristics of contaminants, dramatically altering their atmospheric residence times and fates from those of the parent contaminants. The complex reactions within the atmosphere that are driven by chemical processes such as hydroxyl scavenging... 

You already know that MS studies ions. So, once molecules have been introduced inside the mass spectrometer, they must be ionized, i.e. transformed into ions. The ionization process occurs in the ion source by using an ionization technique. There are different ionization techniques depending on the physico-chemical properties of the molecules. 

Principal component analysis (PCA) of the soil physico-chemical or the antibiotic resistance data set was performed with the SPSS software. Before PCA, the row MPN values were log-ratio transformed (ter Braak and Smilauer 1998) each MPN was logio -transformed, then, divided by sum of the 16 log-transformed values. Simple linear regression analysis between scores on PCs based on the antibiotic resistance profiles and the soil physico-chemical characteristics was also performed using the SPSS software. To find the PCs that significantly explain variation of SFI or SEF value, multiple regression analysis between SFI or SEF values and PC scores was also performed using the SPSS software. The stepwise method at the default criteria (p=0.05 for inclusion and 0.10 for removal) was chosen. 

This transformation of a physico-chemical model into an empirical model was previously discussed by Weyland et al. [27]. A ternary nonlinear blending term is often added to improve the descriptive power of this equation. Then, a special cubic mixture model is obtained ... 

If the ranges of homogeneity of the phases taking part in the transformation are wider than those of line compounds, the kinetic coefficients in Eqns. (12.22) and (12.23), that is v jf, yb, and A b, are certainly not composition independent. It may then be questionable if transport across the boundary (Eqn. (12.22)) and the simultaneous structure change (Eqn. (12.23)) are independent processes as was tacitly assumed by formulating the kinetic relations in Eqns. (12.22) and (12.23). Let us emphasize that the foregoing analysis is meant to clarify the physico-chemical conceptual frame in which first-order transitions which include matter transport should be discussed. Pertinent experiments are still rare. 

The contaminant redox reactions just summarized only occur when coupled with suitable half-reactions involving oxidants or reductants from the environment. In a particular environmental system, these redox agents (along with the physico-chemical factors discussed in section 4.2) collectively determine the nature, rate, and extent of contaminant transformation. Under favorable circumstances, the dominant redox agent(s) can be identified and quantified, thereby providing a rigorous basis for estimating the potential for, and rate of, transformation by abiotic redox reactions. 

R Okamoto, T Fukumoto, H Nomura, K Kiyoshima, K Nakamura, A Takamatsu, H Naganawa, T Takeuchi, H Umezawa. Physico-chemical properties of new acyl derivatives of tylosin produced by microbial transformation. J Antibiot 33 1300-1308, 1980. 

Oct. 24,1895, Kishinev, Russia, now Chisinau, Moldova - May 27, 1976, Moscow, USSR, now Russia) After graduating from the technical college in Odessa (1912) and probation in StraCburg and Bern, he had taken an external degree of Novorossiisk University (1915). The early studies of Frumkin of -> electrocapillary phenomena at electrified interfaces (thesis, 1919) determined his future key directions in electrochemistry and colloid chemistry, continued later in Moscow in the Karpov Physico-chemical Institute (starting from 1922), Moscow University (starting from 1930 in 1933 he founded the Dept, of Electrochemistry there), and in the Institute of Colloid Chemistry and Electrochemistry later transformed into the Institute of Physical Chemistry. Finally, in 1958 Frumkin founded the Institute of Electrochemistry of the USSR Academy of Sciences, and headed it up to his death. 

Numerous applications of positron annihilation spectroscopy (PAS) in investigations of the physico-chemical properties of matter require a precise understanding of the process of Ps formation. Usually it proceeds on a picosecond time scale and is strongly influenced by early (pico- and femtosecond) processes initiated by ionizations in the track of a fast positron. These early intratrack processes initiate all subsequent chemical transformations and, consequently, take a key position in radiation chemistry. 

Equilibria between various forms of living centres were treated in Chap. 5, Sect. 8.1. Equilibria of similar character control the arrangement and reactivity of all ionic centres. When polymerization-inactive structures participate in the equilibria, the number of active centres is reduced by the equilibrium amount of inactive forms. This phenomenon is usually not considered as termination the unreactive particles are treated as dormant. In the course of polymerization, however, the physico-chemical parameters of the system change as a function of the monomer-polymer transformation. Changes in permittivity, viscosity and the amount of polymer can cause shifts in ionization and dissociation equilibria. The kinetic manifestations of such changes are identical with the occurrence of termination. 

J. W. Gall, presented at "Physico-Chemical Transformation of Sulfur Compounds in the Atmosphere and the Formation of Acid Smogs," Mainz (1967). 

Even, J. and Bertault, M. (2000). Transformations in molecular crystals and chemical reactions a physico-chemical approach. Condens. Matter News, 8, 9-21. [223, 237]... 

While the reactoplasts are hardening in the mold, structural transformations associated with the physico-mechanical properties of the material are taking place. In contrast to thermoplasts, the reactoplasts are not characterizal by a widely varying morphological structure. Fundamental structural elements of polymers with a compact reticular structure are globules [40]. 

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