Perrin effect

B. The Mulliken algorithm rather arbitrarily awards half the overlap to each atom. This allocation is admirably democratic and defensible for orbitals of similar diffuseness and shape. However, it rapidly becomes unreasonable for atoms of different electronegativity or hybrids of different composition (similar in origin, but opposite in direction, to the Perrin effect noted above for Bader charges). 

Denis, C., Linossier, M.-T, Dormois, D., Cottier-Perrin, M., Geyssant, A., and Lacour, J,-R. (1989). Effects of endurance training on hyperammonaemia during a 45-min constant exercise intensity. Eur. J. Appi Physiol. 59, 268-272. 

Perrin model and the Johansson and Elvingston model fall above the experimental data. Also shown in this figure is the prediction from the Stokes-Einstein-Smoluchowski expression, whereby the Stokes-Einstein expression is modified with the inclusion of the Ein-stein-Smoluchowski expression for the effect of solute on viscosity. Penke et al. [290] found that the Mackie-Meares equation fit the water diffusion data however, upon consideration of water interactions with the polymer gel, through measurements of longitudinal relaxation, adsorption interactions incorporated within the volume averaging theory also well described the experimental results. The volume averaging theory had the advantage that it could describe the effect of Bis on the relaxation within the same framework as the description of the diffusion coefficient. 

In this chapter, the definitions used by Perrin in his book on pA a prediction (which also includes a very convenient compilation of o values) will be used. One must be alert to the importance of the number of hydrogens directly attached to the carbonyl carbon several groups have pointed out that aldehydes and ketones give separate but parallel lines, with formaldehyde displaced by the same amount again. What this means is that given one equilibrium constant for an aldehyde (or ketone) one may estimate the equilibrium constant for other aldehydes (or ketones) from this value and p for the addition using a value from experiment, if available, or estimated if necessary. This assumes that there is no large difference in steric effects between the reference compound and the unknown of interest. 

The results of this study show a definite quenching of the 418 nm phosphorescence emission of DMT. One would expect that the quenching effect, in a rigid glass, would fit the Perrin model (73). A plot in In 4>0/4> versus concentration of 4,4 -BPDC yielded a straight line, the slope of which was identified with NV. The radius, R, of the active volume of quenching sphere was calculated by the following equation ... 

Just as above, we can derive expressions for any fluorescence lifetime for any number of pathways. In this chapter we limit our discussion to cases where the excited molecules have relaxed to their lowest excited-state vibrational level by internal conversion (ic) before pursuing any other de-excitation pathway (see the Perrin-Jablonski diagram in Fig. 1.4). This means we do not consider coherent effects whereby the molecule decays, or transfers energy, from a higher excited state, or from a non-Boltzmann distribution of vibrational levels, before coming to steady-state equilibrium in its ground electronic state (see Section 1.2.2). Internal conversion only takes a few picoseconds, or less [82-84, 106]. In the case of incoherent decay, the method of excitation does not play a role in the decay by any of the pathways from the excited state the excitation scheme is only peculiar to the method we choose to measure the fluorescence (Sections 1.7-1.11). 

Nemst, for example, argued that physics forms the theoretical basis of all sciences, including chemistry. 18 A statement by Emile Dubois-Reymond to the effect that there was a need for a physical chemistry to create a "mathematical mechanics of knowledge" and a "complete picture of molecular processes" 19 was used to preface the first issue of the Zeitschrift fur physikalische Chemie. For van t Hoff, this was to be achieved through "the application of physical expedients, methods, and instruments to chemical problems" in establishing "comprehensive principles."20 Less concretely, Jean Perrin wrote that "really, there is no particular method proper to chemical physics [but] rather a physicochemical esprit."21 Perrin s successors at the Universite de Paris understood this remark to mean that physical chemistry at the turn of the century was "whatever interested Jean Perrin, just as physical chemistry at Berkeley was whatever interested Gilbert N. Lewis. "22... 

When M and Q cannot change their positions in space relative to one another during the excited-state lifetime of M (i.e. in viscous media or rigid matrices), Perrin proposed a model in which quenching of a fluorophore is assumed to be complete if a quencher molecule Q is located inside a sphere (called the sphere of effective quenching, active sphere or quenching sphere) of volume Vq surrounding the fluorophore M. If a quencher is outside the active sphere, it has no effect at all on M. Therefore, the fluorescence intensity of the solution is decreased by addition of Q, but the fluorescence decay after pulse excitation is unaffected. 

N-methylscopolamine (Costa et al. 1982b Schwab et al. 1983). Animals made tolerant to disulfoton were resistant to the lethal or adverse effects of cholinergic agonists, such as carbachol (Brodeur and DuBois 1964 Costa et al. 1981 Schwab and Murphy 1981) and oxotremorine (Costa et al. 1982b McPhillips 1969a), which are not hydrolyzed by acetylcholinesterase. Tissues from animals tolerant to disulfoton such as the ilea (Foley and McPhillips 1973 McPhillips 1969b McPhillips and Dar 1967) and the atria (Perrine and McPhillips 1970 Schwab et al. 1983), were resistant to the effects of carbachol and/or oxotremorine. Because the uterus and vas deferens have a relatively sparse parasympathetic innervation compared to the ileum and do not receive a steady flow of impulses via this system, these tissues were not as subsensitive to carbachol as the ileum (Foley and McPhillips 1973). Thus, acetylcholine accumulation may be a prerequisite for tolerance development. 

Selected entries from Methods in Enzymology [vol, page(s)] Additive properties of polarization, 246, 286 angle-resolved, assessment of peroxidation effects on membranes, 233, 274-275, 281-283, 287-288 binding isotherm construction, 246, 287-288 effect of inner filter effects, 246, 288 incoherent systems, 246, 263-264 orientational averaging, 246, 265, 269-270 Perrin equation, 246, 284-285 polarization of emission, 246, 284 rotational diffusion, 246, 9, 260 time-resolved, assessment of peroxidation effects on membranes, 233, 274, 283-285, 285-287. 

D. D. Perrin B. Dempsey (1974) Buffers for pH and Metal Ion Control, Wiley, New York. (This handy reference provides detailed procedure that allow one to compensate for pH and temperature effects on metal-ligand interactions as well as buffers.)... 

Reyes TM, Lewis K, Perrin MH, Kunitake KS, Vaughan J, Arias CA, Hogenesch JB, Gulyas J, Rivier J, Vale WW, Sawchenko PE (2001) Urocortin 11 a member of the corticotropinreleasing factor (CRF) neuropeptide family that is selectively bound by type 2 CRF receptors. Proc Natl Acad Sci USA 98 2843-2848 Richard P, Moos F, Freund-Mercier MJ (1991) Central effects of oxytocin. Physiol Rev 71 331-370... 

Perrin DD. 1954. The effect of temperature on pK values of organic bases. Aust J Chem 17 484-488. 

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