Mechanism of transformation

Chow C-F, Fuji S, Lehn J-M. Metallodynamers neutral dynamic metallosupramolecular polymers displaying transformation of mechanical and optical properties on constitutional exchange. Angew Chem Int Ed 2007 46 5007 -5010. 

The mathematics we shall need is confined to the properties of vector spaces in which the scalar values are real numbers. From a mathematical viewpoint the whole discussion will take place in the context of two vector spaces, an S-dimensional space of chemical mechanisms and a Q-dimen-sional space of chemical reactions, which are related to each other by the fact that each mechanism m is associated with a unique reaction R(m) which it produces. The function R is a transformation of mechanisms to reactions which is linear by virtue of the fact that reactions are additive in a chemical system and that the reaction associated with combined mechanisms mt + m2 is R(m,) + R(m2). All mechanisms are combinations of a simplest kind of mechanism, called a step, which ideally consists of a one-step molecular interaction. Each step produces one of the elementary reactions which form a basis for the space of all reactions. 

Linear transformation of mechanism space to reaction space. 

Phase 2. Transformation of mechanical to calorific energy. A portion of the mech energy of the layer which was detond is instantly converted into calorific energy in the adjacent layer. The portion of mech energy which is not converted to heat becomes the actual vehicle through which the work is accomplished... 

Figure 8 Monomers for the block copolymer synthesis by transformation of mechanisms.

Lea MC (1894) Transformation of mechanical into chemical energy. Third part. Acting of shearing stress continued. Am J Sci 147 377-381... 

El-Eskandarany, M. S. Akoi, K Sumiyama, K. Suzuki, K. (1997). Cyclic Crystalline-Amorphous Transformations of Mechanically Alloyed Co7sTi25. Applied Physics Letters, Vol.70, No.l3, pp. 1679-1681. 

A model using the direct flexoelectric effect for the transformation of mechanical into electrical energy in the hearing process in stereocilia has been proposed." ... 

M Umeda, K Nakamura, S Ueha, Analysis of the transformation of mechanical impact raiergy to electric energy using piezoelectric vibrator , Jpn J Apfd Phys, 1996 35(1,58)3267-3273. 

In some cases, the transformation of mechanical energy, i.e. between PKE, PE, and KE, is of primary interest, and isothermal conditions may be assumed. 

Mechanism (Section 4 8) The sequence of steps that descnbes how a chemical reaction occurs a descnption of the inter mediates and transition states that are involved during the transformation of reactants to products... 

The mechanism of oxidative dyeing involves a complex system of consecutive, competing, and autocatalytic reactions in which the final color depends on the efficiency with which the various couplers compete with one another for the available diimine. In addition, hydrolysis, oxidation, or polymerization of diimine may take place. Therefore, the color of a mixture caimot readily be predicted and involves trial and error. Though oxidation dyes produce fast colors, some off-shade fading does occur, particularly the development of a red tinge by the slow transformation of the blue indamine dye to a red phenazine dye. 

Mechanisms. Mechanism is a technical term, referring to a detailed, microscopic description of a chemical transformation. Although it falls far short of a complete dynamical description of a reaction at the atomic level, a mechanism has been the most information available. In particular, a mechanism for a reaction is sufficient to predict the macroscopic rate law of the reaction. This deductive process is vaUd only in one direction, ie, an unlimited number of mechanisms are consistent with any measured rate law. A successful kinetic study, therefore, postulates a mechanism, derives the rate law, and demonstrates that the rate law is sufficient to explain experimental data over some range of conditions. New data may be discovered later that prove inconsistent with the assumed rate law and require that a new mechanism be postulated. Mechanisms state, in particular, what molecules actually react in an elementary step and what products these produce. An overall chemical equation may involve a variety of intermediates, and the mechanism specifies those intermediates. For the overall equation... 

Nickel and other transition metals function as solvent-catalysts for the transformation of carbon species into the diamond aHotrope. At temperatures high enough to melt the metal or metal—carbon mixture and at pressures high enough for diamond to be stable, diamond forms by what is probably an electronic mechanism (see Carbon, diamond-synthetic). 

Transformations in the Solid State. From a practical standpoint, the most important soHd-state transformation of PB involves the irreversible conversion of its metastable form II developed during melt crystallization into the stable form I. This transformation is affected by the polymer molecular weight and tacticity as well as by temperature, pressure, mechanical stress, and the presence of impurities and additives (38,39). At room temperature, half-times of the transformation range between 4 and 45 h with an average half-time of 22—25 h (39). The process can be significantly accelerated by annealing articles made of PB at temperatures below 90°C, by ultrasonic or y-ray irradiation, and by utilizing various additives. Conversion of... 

Gc/k instmments are all of the gc/fdr variety that utilize an interferometer and requke a Fourier transform of the signal as opposed to employing a monochrometer and mechanical scanning. At least 3 scan/second are needed across the capillary gc peaks which are from 3 to 6 seconds wide. 

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. 

The transformation of bulk Hquid to sprays can be achieved in many different ways. Basic techniques iaclude applying hydraulic pressure, electrical, acoustic, or mechanical energy to overcome the cohesive forces within the Hquid. 

Biotin is produced by a multistep pathway in a variety of fungi, bacteria, and plants (50—56). The estabUshed pathway (50,56) in E. coli is shown in Figure 6. However, Htde is known about the initial steps that lead to pimelyl-Co A or of the mechanism of the transformation of desthiobiotin to biotin. Pimelic acid is beheved to be the natural precursor of biotin for some microorganisms (51). 

The transformation toughening mechanism has been most successfully exploited in materials where the phase transformation of interest is... 

Penicillin sulfoxides can be epimerized by heat to afford thermal equilibrium mixtures of a- and /3-sulfoxides, the position of the equilibrium depending on the C(6) side chain (Scheme 5). Deuterium incorporation studies support a sulfenic acid, e.g. (18), as the intermediate in these transformations. This mechanism is also supported by the finding that when an a-sulfoxide epimerizes to a /3-sulfoxide there is a simultaneous epimerization at C(2) (71JCS(C)3540). With irradiation by UV light it is possible to convert a more thermodynamically stable /3-sulfoxide to the a-sulfoxide (69JA1530). 

There are also reactions which show stereoselectivity primarily because of mechanism rather than spatial bias of substrate. For instance, the conversion of an olefin to a 1,2-diol by osmium tetroxide mechanistically is a cycloaddition process which is strictly suprafacial. The hydroxylation transform has elements of both substrate and mechanism control, as illustrated by the retrosynthetic conversion of 146 to 147. The validity of the retrosynthetic removal of both... 

Metabolic rate (M) The rate of transformation of chemical energy into heat and mechanical work by aerobic and anaerobic metabolic activities w ithin an organism, usually expressed per unit area of the total body surface, in met or W m -. 

In this chapter the regimes of mechanical response nonlinear elastic compression stress tensors the Hugoniot elastic limit elastic-plastic deformation hydrodynamic flow phase transformation release waves other mechanical aspects of shock propagation first-order and second-order behaviors. 

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