Atomistic hypothesis

Like many natural philosophers of his day, Boyle was an atomist. He summed up his atomistic hypothesis in Origine of Forms and Qualities, published in 1666, in which he stated his belief that there was one kind of Catholick or Universal Matter which existed in the form of tiny corpuscles of different sizes, shapes, and motions. These properties of the corpuscles caused different chemical substances to have different properties. For example, noting that nitrate crystals were prismatic, Boyle reasoned that the corpuscles that made up the crystals were tiny prisms. He speculated further that it is the sharp ends of these crystals that cause nitric add to be corrosive. Of course... 

It has not yet been clarified whether the ring substituents interact directly with the binding site or affect the molecular characteristics of the DHP molecules in common. A recently used atomistic pseudoreceptor model for a series of DHP indicated a putative charge-transfer interaction was stabilizing the DHP-binding site complex [19]. To prove this hypothesis qualitative and quantitative analysis of the molecular orbitals of nine DHP derivatives (Fig. 9.11) was performed [18]. Charge-transfer (or electron-donor-acceptor) interactions are indicative of electronic... 

Anodic aluminum oxide, 312, 401 Antiferromagnetic-like interactions, 141 Antiferromagnetism, 433 Arc discharge method, 448 Ar ion sputtering, 449 Arrhenius, Carl Axel, 4 Arrhenius-Uke behaviour, 134 Asteriod hypothesis, 46 Atomic force microscope (AFM), 397 Atomistic simulation, 296,297 Au(llO), 137 Au(lll), 135... 

The nuclear atom is the picture of the atom as a positive nucleus surrounded by negative electrons. Although the idea of atoms in speculative philosophy goes back to at least the time of Democrims, the atom as the basis of a scientifically credible theory emerges only in nineteenth century, with the rationalization by Dalton in 1808 of the law of definite proportions. Nevertheless, atoms were regarded by many scientists of the positivist school of Ernst Mach as being at best a convenient hypothesis, despite the success of the atomistic MaxweU-Boltzmaim kinetic theory of gases and it was not until 1908, when Perrin s experiments confirmed Einstein s atomistic analysis of... 

The four-element theory would make it seem that the various substances of the universe differed only in the nature of the elemental mixture. This hypothesis would be true whether one accepted the atomist view or not, since the elements could mix as atoms or as continuous substance. Indeed, there seemed reason to think that even the elements themselves were interchangeable. Water seemed to turn to air when it evaporated, and the air turned back to water when it rained. Wood, if heated, turned to fire and vapors (a form of air) and so on. 

Bohr first proposed an electron motion model to solve the problems of the Rutherford model. For the electron in a hydrogen atom, Bohr presented an atomistic model, in which the periodic orbits of electrons are quantized, and proposed the following hypothesis, known as the Bohr hypothesis (Bohr 1913) ... 

In order to simulate fluid flow, heat transfer, and other related physical phenomena over various length scales, it is necessary to describe the associated physics in mathematical terms. Nearly all the physical phenomena of interest to the fluid dynamics research community are governed by the principles of continuum conservation and are expressed in terms of first- or second-order partial differential equations that mathematically represent these principles (within the restrictions of a continuum-based firamework). However, in case the requirements of continuum hypothesis are violated altogether for certain physical problems (for instance, in case of high Knudsen number rarefied gas flows), alternative formulations in terms of the particle-based statistical tools or the atomistic simulation techniques need to be resorted to. In this entry, we shall only focus our attention to situations in which the governing differential equations physically originate out of continuum conservation requirements and can be expressed in the form of a general differential equation that incorporates the unsteady term, the advection term, the diffusion term, and the source term to be elucidated as follows. 

Thus, the relation between F and Tfluc remains an open question, and simulations can point at the most likely answer. For example, if Ff c = Fframe> the fluctuation tension should vanish for stress-free membranes, i.e., the imdulation spectrum should then be dominated by a behavior. With a few exceptions [169, 170], this has indeed been observed in coarse-grained or atomistic simulations of stress-free lipid bilayers [12, 15, 28, 30, 109, 175] or bilayer stacks [176]. This would seem to rule out the alternative hypothesis Ffluc = Fq. However, it should be noted that the undulation spectra have relatively large error bars and a complex behavior at higher q, as discussed in Sect. 2.3.1. Therefore, the results also depend to some extent on the fit. 

It has already been mentioned that an atomistic view of the constitution of matter was put forward by certain philosophers in ancient Greece (p, 5). They had done this in a purely speculative way moreover, even their speculations were heavily discounted by the weighty influence of Aristotle s opposed view of the continuity of matter. The Atomic Theory of John Dalton (1776-1844) owed nothing to any of the thinkers of ancient Greece to what has been termed the airy hypothesis of a philosopher who soars above the vulgar paths of observation and experience. In the seventeenth century, both Gassendi and Boyle had held atomistic views and, far more important, Netvton, with his unprecedented mathematical and physical knowledge, also held the opinion that matter possessed an atomic constitution. 

Following the conclusions of Takeuchi, one may ask whether the transition from a perfect to a dissociated core in shicon could be relevant to the dissociation of a perfect dislocation located in the ghde set, which dissociates as soon as temperature and stress ahow for the partial dislocations to move. This hypothesis can be ruled out, however, on the basis of the atomistic calculations on dislocation nucleation (Section 3.2.4), where dislocations were found to be nucleated as perfect ones in the shuffle set at high stress and in a dissociated form in the ghde set at high temperature. 

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