Laser flash photolysis has been used to determine the second-order rate constants for the reduction of horse heart cytochrome c by the semiquinone and fully reduced forms of various flavin analogs. We find that substitution in the dimethylbenzene ring of the flavin causes appreciable changes in the rate constants, whereas substitutions at the N-10 position do not. Placing a charged phosphate gr...

The collision-induced Zeeman relaxation rate for collisions of CaF X2Sigma(v('')=0) with 3He is measured to be Gamma(Z)=(7.7+5.4/-2.5)x10(-15) cm(3)/s at 2 K. This rate is a direct measurement of the influence of spin-rotation coupling on Zeeman relaxation in the first rotational level of CaF. The relationship of this rate to known molecular constants is consistent with recent theory of cold mo...

We study vibrational deactivation processes on chemically reactive potential energy surfaces by examining accurate quantum mechanical transition probabilities and rate constants for the collinear H + FH(v ), D + FD(v), H + FD(v}, and D + FH(v) reactions. A low barrier (1.7 kcal!mole} potential surface is used in these calculations, and we find that for all four reactions, the reactive inelastic...

Formal collision theory indicates that the absolute termolecular recombination reaction rate can be expressed in a form associated either with direct or indirect mechanisms for the recombination. Moreover, the same exact rate constant can be calculated using either of the four mechanisms. These results are to be contrasted to the rate constants standardly calculated by approximate methods. © 19...

A new coercivity estimate on the spectral gap of the linearized Boltzmann collision operator for multiple species is proved. The assumptions on the collision kernels include hard and Maxwellian potentials under Grad’s angular cut-off condition. Two proofs are given: a non-constructive one, based on the decomposition of the collision operator into a compact and a coercive part, and a constructiv...

Binary fluorescence time series obtained from single-molecule imaging experiments can be used to infer protein binding kinetics, in particular, association and dissociation rate constants from waiting time statistics of fluorescence intensity changes. In many cases, rate constants inferred from fluorescence time series exhibit nonintuitive dependence on ligand concentration. Here, we examine se...

Symmetry breaking of the excited state of a linear quadrupolar acceptor-donor-acceptor molecule was investigated using time-resolved infrared spectroscopy in 55 solvents allowing the influence of several solute-solvent interactions to be examined separately. No symmetry breaking was found in nonpolar solvents irrespective of their refractive index, indicating that differences in dispersion inte...

Monte Carlo simulations are presented for a coarse-grained model of real quadrupolar fluids. Molecules are represented by particles interacting with Lennard-Jones forces plus the thermally averaged quadrupole-quadrupole interaction. The properties discussed include the vapor-liquid coexistence curve, the vapor pressure along coexistence, and the surface tension. The full isotherms are also acce...

The morphogenesis of vertebrate body parts remains an open question. It is not clear whether the existence of different structures, such as a head, can be addressed by fundamental laws of tissue movement and deformation, or whether they are only a sequence of stop-and-go genetic instructions. I have filmed by time-lapse microscopy the formation of the presumptive head territory in chicken embry...