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Large-scale networks of phase synchronization are considered to regulate the communication between brain regions fundamental to cognitive function, but the mapping to their structural substrates,i.e., the structure-function relationship, remains poorly understood. Biophysical Network Models (BNMs) have demonstrated the influences of local oscillatory activity and inter-regional anatomical connections in generating alpha-band (8–12 Hz) networks of phase synchronization observed with Electroencephalography (EEG) and Magnetoencephalography (MEG). Yet, the influence of inter-regional conduction delays remains unknown. In this study, we compared a BNM with standard “distance-dependent delays”, which assumes constant conduction velocity, to BNMs with delays specified by two alternative methods accounting for spatially varying conduction velocities, “isochronous delays” and “mixed delays”. We followed the Approximate Bayesian Computation (ABC) workflow, i) specifying neurophysiologically informed prior distributions of BNM parameters, ii) verifying the suitability of the prior distributions with Prior Predictive Checks, iii) fitting each of the three BNMs to alpha-band MEG resting-state data (N= 75) with Bayesian Optimisation for Likelihood-Free Inference (BOLFI), and iv) choosing between the fitted BNMs with ABC model comparison on a separate MEG dataset (N= 30). Prior Predictive Checks revealed the range of dynamics generated by each of the BNMs to encompass those seen in the MEG data, suggesting the suitability of the prior distributions. Fitting the models to MEG data yielded reliable posterior distributions of the parameters of each of the BNMs. Finally, model comparison revealed the BNM with “distance-dependent delays”, as the most probable to describe the generation of alpha-band networks of phase synchronization seen in MEG. These findings suggest distance-dependent delays contribute significantly to the neocortical architecture of human alpha-band networks of phase synchronization. Hence, our study illuminates the role of inter-regional delays in generating the large-scale networks of phase synchronization that might subserve the communication between regions vital to cognition.HighlightsCompared methods to specify delays in Biophysical Network Models (BNMs)BNM with “distance-dependent” conduction delays more probable than alternativesBNMs with biologically informed prior distributions generate dynamics seen in MEGFitting BNMs yields reliable posterior distributions informed by MEG data (N= 75)

A simple model based on the solution of the master equation, but including rotational effects in the first discrete levels, has been used to model the sigma/sub L/ (Phi) and reaction probability results for CDF/sub 3/ in a wide range of experimental conditions. The authors investigated the role played by collisions in order to overcome restrictions to the absorption processes, which is a striking feature of small molecules. By solving the rate equations the authors have been able to obtain information about the rotational relaxation rate of CDF/sub 3/ by collisions with CDF/sub 3/, CHF/sub 3/, and Ar as well as information about the average energy transferred by collisions between the different buffer gases and the vibrationally excited CDF/sub 3/. For CDF/sub 3/ (CHF/sub 3/) as collide the values determined are k/sub rot/ (CDF/sub 3/-CDF/sub 3/) = k/sub rot/ (CDF/sub 3/-CHF/sub 3/) = (3.0-6.0) x 10/sup -3/ ns/sup -1/ Torr/sup -1/ and (..delta..E)/sub d/ = 3 kcal mol/sup -1/, and for Ar as bath gas, k/sub rot/ (CDF/sub 3/-Ar) = 6.7 x 10/sup -4/ ns/sup -1/ Torr/sup -1/ and (..delta..E)/sub d/ < 0.7 kcal mol/sup -1/.

The concept of preferential solvation has been used to detect and quantify specific interactions, particularly electron—donor—acceptor (EDA) interactions for the solutes 1-cyanonaphthalene and 1,2-dicyanobenzene which can act as π electron acceptors. These acceptors have been studied in binary solvent mixtures, in which one of the solvents can act as an electron donor while the other is an “inert” cosolvent. Thus we analysed the preferential solvation of the aromatic compounds in the following mixtures: cyclohexane—diethylether, cyclohexane—diethylamine, diethylamine—diethylether, cyclohexane-diisopropylamine, cyclohexane—diisopropylether and diisopropylamine—diisopropylether. The evaluation of the degree of preferential solvation was performed by an analysis of the intensity enhancements of the vibronic absorption spectral bands of the acceptors in the binary mixtures. This method seems to be a useful approach to observing preferential solvation, is proposed as a method to detect EDA interaction, for systems where no new bands are observed such as in complexes between cyanoaromatics and aliphatic amines.

A solvatochromic study of the vibronic fine structure of the 1Lb absorption band of 1,2-dicyanobenzene (DCB), in several non-polar and polar solvents including aliphatic amines was made. The spectral properties were analyzed by means of theoretical parameters as well as by K amlet and T aft 's solvatochromic comparison method. The solvatochromic behavior of the 1Lb absorption band of DCB has been accounted fundamentally as dielectric in nature except for the aliphatic amines as solvents. The anomalous behavior of aliphatic amines is explained by considering that the solute interacts via electron donor-acceptor (EDA) complex formation with these solvents. A qualitative approach based on the use of the ratio of vibronic band intensities is proposed as a sensible method to detect these type of EDA interactions.